JP7730866B2 - Electrode, electrode composite, secondary battery, and method for manufacturing electrode - Google Patents

Description

This disclosure relates to electrodes for use in secondary batteries, electrode assemblies, secondary batteries, and methods for manufacturing electrodes.

Generally, secondary batteries consist of electrodes (positive and negative electrodes) and an electrolyte, and charge and discharge occur through the movement of ions between the electrodes via the electrolyte. Such secondary batteries are used in a wide range of applications, from small devices such as mobile phones to large devices such as electric vehicles. Therefore, further improvements in the performance of secondary batteries are required. In recent years, research and development of so-called all-solid-state batteries, which use inorganic solid electrolytes as the electrolyte, has progressed. By replacing conventional organic electrolytes with solid electrolytes, all-solid-state batteries are expected to improve the safety and increase the capacity and output of secondary batteries.
On the other hand, in all-solid-state batteries, the contact between the electrolyte and the active material particles is easily broken due to the expansion and contraction of the active material particles during the process of ion insertion and desorption in the electrode. As a result, in all-solid-state batteries, the insertion and desorption of ions such as lithium ions into the active material particles is blocked, increasing the resistance of the electrode and significantly reducing the charge/discharge current, or so-called output characteristics. To address this issue, a technology has been known in which a lithium ion conductive polymer, which is more flexible than the electrolyte particles, is placed inside the electrode.
Patent Document 1 discloses an electrode in which the outer surfaces of active material particles are partially coated with a lithium ion conductive polymer.

Japanese Patent Application Laid-Open No. 2002-373643 Japanese Patent Application Laid-Open No. 2020-198301

However, the present inventors have found that simply partially coating the outer surfaces of the active material particles with a polymer is not sufficient to improve the diffusibility of lithium ions within the electrode, for the following reasons.
That is, active material particles in an electrode expand and contract during charging and discharging. Adjacent active material particles also expand and contract similarly. Therefore, even if the outer surfaces of active material particles are only partially coated with a polymer, the diffusion paths of lithium ions between the active material particles, consisting of the polymer and electrolyte particles, are easily blocked. Furthermore, in the active material particles of Patent Document 1, the surfaces of the active material particles are partially coated with a polymer and electrolyte particles, respectively. Therefore, contact between the polymer and the electrolyte particles is also limited, and the contact is easily blocked by the expansion and contraction of the active material particles. Therefore, the diffusion of lithium ions is easily restricted between the active material particles and the polymer. As a result, even in solid electrolytes, which generally have higher ionic conductivity than polymers, the effect of ion diffusion is easily reduced.

Furthermore, Patent Document 1 discloses methods such as mechanical milling and chemical coating treatment as methods for partially coating the surfaces of active material particles. However, these treatment methods make it difficult to achieve a uniform coating area and thickness for each particle, and there are also problems with reproducibility as an electrode manufacturing method.

The present disclosure provides an electrode that can mitigate expansion and contraction of active material particles and suppress a decrease in battery output when used in a secondary battery. The present disclosure also provides an electrode composite including the electrode of the present disclosure. In addition, the present disclosure provides a secondary battery in which a decrease in battery output is suppressed. Furthermore, the present disclosure provides a method for producing an electrode with high reproducibility.

An electrode according to one aspect of the present disclosure comprises:
An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
the conductive resin is positioned so as to be in contact with the inner surface,
The conductive resin is characterized by including a resin containing an ionic functional group and a supporting electrolyte .
An electrode according to one aspect of the present disclosure comprises:
An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
the conductive resin is positioned so as to be in contact with the inner surface,
The conductive resin is characterized by including a urethane resin containing an ionic functional group and a supporting electrolyte.
An electrode according to one aspect of the present disclosure comprises:
An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
the conductive resin is positioned so as to be in contact with the inner surface,
A supporting electrolyte is contained between the active material particles, and the supporting electrolyte contains an inorganic electrolyte.
An electrode according to one aspect of the present disclosure comprises:
An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
the conductive resin is positioned so as to be in contact with the inner surface,
the inner surface is continuous with the outer surface of the active material particle,
The active material particles are characterized by having protrusions protruding from the outer surface.

An electrode composite according to one aspect of the present disclosure includes:
An electrode composite including an electrode and an electrolyte layer that transfers an active material between the electrode and the electrolyte layer,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
The conductive resin is positioned so as to be in contact with the inner surface.
An electrode composite according to one aspect of the present disclosure includes:
an electrode; and an electrolyte layer that transfers an active material between the electrode and the electrolyte layer;
The electrode is characterized in that it is the electrode of the present disclosure.

A secondary battery according to one aspect of the present disclosure includes:
a positive electrode and an electrolyte layer that transfers an active material between the positive electrode and the electrolyte layer;
The positive electrode is the electrode according to any one of claims 1 to 22,
The secondary battery is characterized in that it includes a negative electrode that transfers the active material between itself and the electrolyte layer.

A method for manufacturing an electrode according to one aspect of the present disclosure includes:
a 1-1 step of preparing an electrode precursor including active material particles and having gaps between the active material particles;
a 2-1 step of preparing a filling material to be filled into the electrode precursor;
a 3-1 step of filling the filling material from the outside to the inside of the electrode precursor;
and a 4-1 step of retaining the filler material filled inside the electrode precursor inside the electrode precursor.

The present disclosure provides an electrode that can mitigate expansion and contraction of active material particles and suppress a decrease in battery output characteristics when used in a secondary battery. The present disclosure also provides an electrode composite that includes the electrode of the present disclosure. Furthermore, the present disclosure can provide a secondary battery in which a decrease in battery output is suppressed. Additionally, the present disclosure can provide a method for manufacturing an electrode with high reproducibility.

FIG. 1 is an image diagram showing a method for producing an electrode precursor. FIG. 1 is a diagram schematically illustrating the configuration of a particle placement device 1. FIG. 2 is a diagram schematically illustrating the configuration of a filling device. Schematic diagram of a filler being carried on a first substrate. FIG. 2 is an enlarged view of the vicinity of the surface of the first substrate. FIG. 10 is a diagram schematically illustrating the configuration of a filling device when brush fibers are used as a support material. FIG. 2 is a diagram schematically illustrating the configuration of a transfer unit. 10 is an enlarged view of the vicinity of the surface of the second substrate during the filling process by the second filling device. FIG. 2 is a diagram schematically showing the second substrate after the first particles P1 and the second particles P2 have been transferred. FIG. 2 is a diagram schematically showing the configuration of a particle placement device 2. FIG. 2 is a diagram schematically illustrating the configuration of a laminate forming apparatus. FIG. 2 is a diagram schematically illustrating the configuration of a sintering treatment apparatus. 10 shows SEM images of a laminate and a three-dimensional object at each step of the electrode manufacturing method. 1 is a BIB-SEM image of a three-dimensional object according to one embodiment of the present disclosure. FIG. 1 is an explanatory diagram of a mechanism relating to a three-dimensional object according to one embodiment of the present disclosure. FIG. 2 is a diagram showing the results of thermogravimetry of a resin substrate. FIG. 1 shows the results of thermogravimetry and mass spectrometry measurements. FIG. 10 shows LCO particles after the third step. FIG. 10 shows the results of STEM-EDX on LCO particles after the third step. 1 is an image diagram showing a method for manufacturing an electrode. FIG. 3 is a schematic diagram showing one embodiment of Step 3-1. FIG. 1 is a diagram showing a charge/discharge curve of a secondary battery. FIG. 2 is a diagram showing an electron microscope image of a cross section of a positive electrode. FIG. 2 is a low-magnification electron microscope image of a cross section of a positive electrode. 1 is a schematic diagram illustrating features of the present disclosure. FIG. 2 is a diagram showing an electron microscope image of a cross section of a positive electrode.

In this disclosure, expressions such as "XX or more and YY or less" or "XX to YY" that represent a numerical range mean a numerical range that includes the endpoints, that is, the lower and upper limits, unless otherwise specified. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way. Furthermore, in this disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ.

As a result of research by the inventors, it was found that it is important to place a conductive resin (polymer) in an appropriate position relative to the active material particles within the electrode. This makes it easier to mitigate the expansion and contraction of each active material particle within the electrode while suppressing a decrease in ion diffusion within the electrode. In this disclosure, the electrode of the present disclosure is realized by filling the electrode precursor with a polymer using the method described below and retaining it inside the electrode precursor. In this disclosure, the mitigation of expansion and contraction of each active material particle is conveniently evaluated using an index known as the "cycle characteristics" of the prototype battery, and ionic conductivity is conveniently evaluated using an index known as the "rate characteristics" of the prototype battery.

The electrode disclosed herein is an electrode for use in a secondary battery. The electrode also includes active material particles and a conductive resin. By including the active material particles and the conductive resin in the electrode, ions can be transferred between the electrodes via the electrolyte, allowing the electrode to be used.

The active material particles preferably have an inner surface, and the conductive resin is preferably positioned so as to be in contact with the inner surface of the active material particles, where the inner surface refers to the surface present on the inside of the active material particles.
In this way, by having the conductive resin in contact with the inner surface of the active material particles, the flexibility of the conductive resin alleviates the expansion and contraction of the active material particles, while making it easier to suppress a decrease in ion diffusion within the electrode, thereby suppressing a decrease in output characteristics. For example, by performing a sintering treatment as in the third step described below, the active material particles can be made to have an inner surface within the particles. Furthermore, by filling the electrode precursor with a filler material as in the third step described below, the conductive resin can be positioned so as to be in contact with the inner surface of the active material particles. The fact that the active material particles have an inner surface within the particles can be confirmed by the measurement method described below. Furthermore, the fact that the conductive resin is positioned so as to be in contact with the inner surface of the active material particles can be confirmed by the measurement method described below.

The inner surfaces of the active material particles preferably have internal pores (hereinafter also referred to as "communicating pores") that communicate with the outer surfaces of the active material particles. By forming such internal pores, it becomes easier to position the filler material so that it contacts the inner surfaces of the active material particles during the step 3-1 described below.
An example of a method for forming such inner pores is a sintering treatment such as that in the third step described below. Whether or not the inner surfaces of the active material particles have such inner pores can be confirmed by a measurement method described below.

Furthermore, it is preferable that the inner surface of the active material particle is continuous with the outer surface of the active material particle, which makes it easier to position the conductive resin so that it contacts the inner surface of the active material particle in the step 3-1 described below.
Moreover, examples of active material particles having such an inner surface include active material particles having a core portion and a shell portion.
As a method for forming such an inner surface, for example, a sintering process such as that in the third step described below can be mentioned.

The active material particles preferably have outer surfaces, and the conductive resin is preferably disposed in contact with the outer surfaces of the active material particles so as to connect the active material particles together. Here, the outer surfaces refer to the surfaces that exist on the outside of the active material particles.
In this way, the conductive resin is arranged in contact with the outer surfaces of the active material particles and connects the active material particles, and the flexibility of the conductive resin helps to mitigate the expansion and contraction of the active material particles while also making it easier to suppress a decrease in ion diffusion within the electrode, thereby suppressing a decrease in output characteristics.
For example, by filling the electrode precursor with a filler material as in step 3-1 described below, the conductive resin can be arranged so as to contact the outer surfaces of the active material particles and connect the active material particles. Whether the conductive resin is in contact with the outer surfaces of the active material particles and arranged so as to connect the active material particles can be confirmed by the measurement method described below.

The active material particles preferably have protrusions. The shape of the protrusions is not particularly limited, and examples include whiskers, which are beard-like, and dendrites, which are dendritic. Furthermore, the protrusions may, for example, protrude from the outer surface. Having such protrusions increases the surface area of the active material particles. As a result, when the electrode contains an electrolyte, the contact area with the electrolyte can be increased. Furthermore, the protrusions can be formed, for example, by performing a sintering process, as in the third step described below. Whether the active material particles have protrusions can be confirmed by cross-sectional observation of the electrode, as described below.

The active material particles are not particularly limited, and known active material particles can be used. For example, a composite oxide containing lithium can be used. Specific examples include Li-Co oxide active material particles such as LiCoO ₂ (lithium cobalt oxide), active material particles such as LiMO ₂ (M is one element selected from the group consisting of Ni, Mn, and Co), Li-PO ₄ oxide active material particles, lithium vanadium compounds (Li ₃ V ₂ (PO ₄ ) ₃ , LiVOPO ₄ ), and olivine-type phosphate compounds (LiMPO ₄ (M is one or more elements selected from the group consisting of Co, Ni, Mn, Fe, Mg, V, Nb, Ti, Al, and Zr)). Active material particles that do not contain lithium may also be used. Specific examples include metal oxides (MnO ₂ , V ₂ O ₅ , etc.) and fluorides (FeF ₃ , VF ₃ , etc.) When using active material particles that do not contain lithium, they can be used by disposing lithium-containing metallic lithium or a lithium ion-doped anode active material as the anode active material and starting with discharge.
Furthermore, negative electrode active material particles such as graphite, Si, and lithium titanate (LTO) can also be used.

The present inventors have clarified that, among the above-mentioned positive electrode active material particles, the use of Li—Co oxide-based active material particles increases the surface area of the positive electrode active material particles and improves the output characteristics of the secondary battery (Patent Document 2). Furthermore, Li— _PO4 oxide-based active material particles are very stable due to the strong covalent bond between P—O and the suppression of oxygen release. Therefore, among the above-mentioned positive electrode active material particles, it is preferable to include Li—Co oxide-based active material particles and Li— _PO4 oxide-based active material particles.

The active material particles may be commercially available products or may be separately prepared as materials.
Examples of Li-Co oxide active material particles that can be used include CellSeed C-5H (trade name, manufactured by Nippon Chemical Industry Co., Ltd.) (LiCoO ₂ ). Examples of LiMO ₂ (M is an element selected from the group consisting of Ni, Mn, and Co) include CellSeed NMC (trade name, manufactured by Nippon Chemical Industry Co., Ltd.) (LiNi _(1-x-y) Mn _x Co _y O ₂ ). Examples of Li-PO ₄ oxide active material particles that can be used include Li ₃ V ₂ (PO ₄ ) ₃ (manufactured by Tokyo Chemical Industry Co., Ltd.) and LiFePO ₄ (manufactured by Toshima Manufacturing Co., Ltd.).
When active material particles having low electron conductivity such as Li ₃ V ₂ (PO ₄ ) ₃ or LiFePO ₄ are used, the particle surfaces may be coated with carbon by a general method.
The active material particles may be used alone or in combination of two or more.

The electrode preferably contains at least one selected from the group consisting of a conductive resin, a conductive additive, and a supporting electrolyte between the active material particles, and more preferably contains a conductive resin and a supporting electrolyte between the active material particles. This improves the diffusibility of lithium ions within the electrode and reduces electrode resistance. Furthermore, by reducing the number of isolated active material particles that cannot exchange lithium ions within the electrode, the actual capacity of the battery can be improved.
The fact that the electrode contains at least one selected from the group consisting of a conductive resin, a conductive additive, and a supporting electrolyte between the active material particles can be confirmed by the results of element mapping in the cross-sectional observation described below.

The conductive resin is not particularly limited, and any known resin can be used as long as it has conductivity. For example, the conductive resin may be a resin with ionic conductivity. Examples of the conductive resin include gel electrolytes and dry polymer electrolytes. From the viewpoint of safety, dry polymer electrolytes that do not contain flammable electrolytic solutions are preferred.
The conductive resin preferably contains at least one of polyurethane, polyacrylic, and polyether in its main chain structure. Polyether, urethane resin containing polyether, and acrylic resin containing polyether are more preferred, and urethane resin containing polyether is even more preferred. The polyether is preferably a copolymer of polyethylene glycol and polypropylene glycol.
The conductive resin preferably contains an ionic functional group such as a cationic structure in its structure to have conductivity. The conductive resin preferably contains an anion. Furthermore, the conductive resin may have conductivity by containing a conductive assistant or a supporting electrolyte.

The ionic group is preferably at least one cationic structure selected from the group consisting of cationic nitrogen-containing heterocyclic structures and ammonium cations having a linear or branched structure.
The cationic nitrogen-containing heterocyclic structure is not particularly limited, but may be a four- to eight-membered ring.
Examples of the cationic nitrogen-containing heterocyclic structure include cationic nitrogen-containing aromatic heterocyclic structures such as imidazolium cation, pyridinium cation, pyrazinium cation, pyrimidinium cation, azepinium cation, quinolinium cation, isoquinolinium cation, indolinium cation, quinoxalinium cation, triazolium cation, triazinium cation, and thiazolinium cation; and cationic nitrogen-containing aliphatic heterocyclic structures such as pyrrolidinium cation, pyrrolinium cation, imidazolinium cation, imidazolidinium cation, piperazinium cation, azepanium cation, diazepanium cation such as 1,3-diazepanium cation and 1,4-diazepanium cation, azocanium cation, oxazolinium cation, and morpholinium cation. Among these, the cationic nitrogen-containing aromatic heterocyclic structure is preferably at least one selected from the group consisting of imidazolium cation, pyridinium cation, and pyrazinium cation, and more preferably an imidazolium cation. The cationic nitrogen-containing aliphatic heterocyclic structure is preferably at least one selected from the group consisting of a pyrrolidinium cation and a piperazinium cation, and more preferably a pyrrolidinium cation.

Examples of the ammonium cation having a straight chain or branched structure include primary ammonium cations, secondary ammonium cations, tertiary ammonium cations and quaternary ammonium cations, and among these, quaternary ammonium cations are preferred.
The hydrocarbon group of the ammonium cation is not particularly limited, and may be, for example, a hydrocarbon group having 1 to 8 carbon atoms (preferably 1 to 4, more preferably 1 to 2, and even more preferably 1). The ammonium cation having a linear or branched structure may have a structure represented by the following formula (4):
The cationic structure may have any substituent, such as a hydrocarbon group. For example, the cationic structure preferably includes at least one structure selected from the group consisting of structures represented by the following formulas (1) to (6). Each structure represented by formulas (1) to (6) will be described below.

The structure represented by formula (1) will be described below.

In formula (1), R ¹ and R ² represent hydrocarbon groups which form a five-membered nitrogen-containing aromatic heterocyclic structure together with the nitrogen atom to which they are bonded, Z ¹ to Z ³ each independently represent a structure represented by the following formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, at least one of Z ¹ to Z ³ represents a structure represented by the following formula (X), and d ¹ represents an integer of 0 to 3 (preferably 0 or 1).

The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom.
The hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 or 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups.
The structure represented by formula (1) represents a cation of a five-membered nitrogen-containing aromatic heterocyclic structure having at least one structure represented by the following formula (X) and two nitrogen atoms. The nitrogen-containing aromatic heterocyclic structure in formula (1) is preferably, for example, an imidazolium cation.
The method for incorporating the structure represented by formula (1) into the structure of a conductive resin is not particularly limited. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (1) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the five-membered nitrogen-containing aromatic heterocyclic structure represented by formula (1) with an isocyanate compound.

As the five-membered nitrogen-containing aromatic heterocyclic structure in formula (1), the cationic nitrogen-containing aromatic heterocyclic structures described in the above section on cation structures can be used, and among these, imidazolium cations are preferred.
Examples of ionic compounds having a structure corresponding to the cation of the five-membered nitrogen-containing aromatic heterocyclic structure in formula (1) include ionic compounds in which at least one of Z ¹ to Z ³ in formula (1) is a linear or branched divalent hydrocarbon having a hydroxyl group. Examples of such ionic compounds include ionic compounds containing an imidazolium cation, as shown below.

1-methyl-3-hydroxymethylimidazolium cation, 1-methyl-3-(2-hydroxyethyl)imidazolium cation, 1-methyl-3-(3-hydroxypropyl)imidazolium cation, 1-methyl-3-(4-hydroxybutyl)imidazolium cation, 1-ethyl-3-(2-hydroxyethyl)imidazolium cation, 1-n-butyl-3-(2-hydroxyethyl)imidazolium cation, 1,3-dimethyl-2-(2-hydroxyethyl)imidazolium cation, 1,3-dimethyl-2-(4-hydroxybutyl)imidazolium cation, 1,3-dimethyl-4-(2-hydroxyethyl)imidazolium cation;
1,3-bishydroxymethylimidazolium cation, 1,3-bis(2-hydroxyethyl)imidazolium cation, 2-methyl-1,3-bishydroxymethylimidazolium cation, 2-methyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 4-methyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 2-ethyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 4-ethyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 2-n-butyl 1,3-bis(2-hydroxyethyl)imidazolium cation, 4-n-butyl-1,3-bis(2-hydroxyethyl)imidazolium cation, 1,3-bis(3-hydroxypropyl)imidazolium cation, 1,3-bis(4-hydroxybutyl)imidazolium cation, 1-methyl-2,3-bis(2-hydroxyethyl)imidazolium cation, 1-methyl-3,4-bis(2-hydroxyethyl)imidazolium cation, 1-methyl-3,5-bis(2-hydroxyethyl)imidazolium cation;
1,2,3-trishydroxymethylimidazolium cation, 1,2,3-tris(2-hydroxyethyl)imidazolium cation, 1,2,3-tris(3-hydroxypropyl)imidazolium cation, 1,2,3-tris(4-hydroxybutyl)imidazolium cation, 1,3,4-trishydroxymethylimidazolium cation, 1,3,4-tris(2-hydroxyethyl)imidazolium cation, 1,3,4-tris(3-hydroxypropyl)imidazolium cation, 1,3,4-tris(4-hydroxybutyl)imidazolium cation;
and their derivatives.

The structure represented by formula (2) will be described below.

In formula (2), ^R3 represents a hydrocarbon group which forms a nitrogen-containing aromatic heterocyclic structure together with the nitrogen atom to which it is bonded; ^Z4 and ^Z5 each independently represent a structure represented by formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having a hydroxyl group and having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), at least one of ^Z4 and ^Z5 represents a structure represented by formula (X), and ^d2 represents an integer of 0 to 5 (preferably 0 or 1).

The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom.
The hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 or 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups.
The structure represented by formula (2) represents a cation of a nitrogen-containing aromatic heterocyclic structure having at least one structure represented by the following formula (X). The nitrogen-containing aromatic heterocyclic structure in formula (2) may be a five- to eight-membered ring, and is preferably a five- or six-membered ring. The nitrogen-containing aromatic heterocyclic structure in formula (2) is preferably, for example, a pyridinium cation.
There are no particular limitations on the method for incorporating the structure represented by formula (2) into the structure of a conductive resin. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (2) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the nitrogen-containing aromatic heterocyclic structure represented by formula (2) with an isocyanate group.

As the nitrogen-containing aromatic heterocyclic structure in formula (2), the cationic nitrogen-containing aromatic heterocyclic structures described in the above section on cation structures can be used, and among these, pyridinium cations are preferred.
Examples of ionic compounds having a structure corresponding to the cation of the nitrogen-containing aromatic heterocyclic structure in formula (2) include ionic compounds in which at least one of ^Z4 and ^Z5 in formula (2) is a linear or branched divalent hydrocarbon having a hydroxyl group. Examples of such ionic compounds include ionic compounds containing a pyridinium cation, such as:

1-hydroxymethylpyridinium cation, 1-(2-hydroxyethyl)pyridinium cation, 1-(3-hydroxypropyl)pyridinium cation, 1-(4-hydroxybutyl)pyridinium cation, 2-methyl-1-(2-hydroxyethyl)pyridinium cation, 3-methyl-1-(2-hydroxyethyl)pyridinium cation, 4-methyl-1-(2-hydroxyethyl)pyridinium cation, 3-ethyl-1-(2-hydroxyethyl)pyridinium cation, 3-n-butyl-1-(2-hydroxyethyl)pyridinium cation, 1-methyl-2-hydroxymethylpyridinium cation, 1-methyl-3-hydroxymethylpyridinium cation, 1-methyl-4-hydroxymethylpyridinium cation, 1-methyl-2-(2-hydroxyethyl)pyridinium cation, 1-methyl-3-(2-hydroxyethyl)pyridinium cation, 1-methyl-4-(2-hydroxyethyl)pyridinium cation, 1-ethyl-3-(2-
1-n-butyl-3-(2-hydroxyethyl)pyridinium cation, 1-n-butyl-3-(2-hydroxyethyl)pyridinium cation, 2-methyl-4-n-butyl-1-(2-hydroxyethyl)pyridinium cation;
1,2-bishydroxymethylpyridinium cation, 1,3-bishydroxymethylpyridinium cation, 1,4-bishydroxymethylpyridinium cation, 1,2-bis(2-hydroxyethyl)pyridinium cation, 1,3-bis(2-hydroxyethyl)pyridinium cation, 1,4-bis(2-hydroxyethyl)pyridinium cation, 1,2-bis(3-hydroxypropyl)pyridinium cation, 1,2-bis(3-hydroxypropyl)pyridinium cation, 1,3-bis(3-hydroxypropyl)pyridinium cation, 1, 4-bis(3-hydroxypropyl)pyridinium cation, 1,2-bis(4-hydroxybutyl)pyridinium cation, 1,3-bis(4-hydroxybutyl)pyridinium cation, 1,4-bis(4-hydroxybutyl)pyridinium cation, 2-methyl-1,3-bis(2-hydroxyethyl)pyridinium cation, 2-ethyl-1,3-bis(2-hydroxyethyl)pyridinium cation, 5-methyl-1,3-bis(2-hydroxyethyl)pyridinium cation, 5-ethyl-1,3-bis(2-hydroxyethyl)pyridinium cation;
1,2,4-trishydroxymethylpyridinium cation, 1,2,4-tris(2-hydroxyethyl)pyridinium cation, 1,2,4-tris(3-hydroxypropyl)pyridinium cation, 1,2,4-tris(4-hydroxybutyl)pyridinium cation, 1,3,5-trishydroxymethylpyridinium cation, 1,3,5-tris(2-hydroxyethyl)pyridinium cation, 1,3,5-tris(3-hydroxypropyl)pyridinium cation, 1,3,5-tris(4-hydroxybutyl)pyridinium cation;
and their derivatives.

The structure represented by formula (3) will be described below.

In formula (3), R ⁴ and R ⁵ represent hydrocarbon groups which form a six-membered nitrogen-containing aromatic heterocyclic structure together with the nitrogen atom to which they are bonded, Z ⁶ and Z ⁷ each independently represent a structure represented by the following formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, at least one of Z ⁶ and Z ⁷ represents a structure represented by the following formula (X), and d ³ represents an integer of 0 to 4 (preferably 0 to 2).

The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom.
The hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 or 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups.
The structure represented by formula (3) represents a cation of a six-membered nitrogen-containing aromatic heterocyclic structure having at least one structure represented by the following formula (X) and two nitrogen atoms. The nitrogen-containing aromatic heterocyclic structure in formula (3) is preferably, for example, a pyrazinium cation.
The method for incorporating the structure represented by formula (3) into the structure of a conductive resin is not particularly limited. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (3) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the six-membered nitrogen-containing aromatic heterocyclic structure represented by formula (3) with an isocyanate compound.

As the six-membered nitrogen-containing aromatic heterocyclic structure in formula (3), the cationic nitrogen-containing aromatic heterocyclic structures described in the above section on cation structures can be used, and among these, pyrimidinium cations and pyrazinium cations are preferred.
Examples of ionic compounds having a structure corresponding to the cation of the six-membered nitrogen-containing aromatic heterocyclic structure in formula (3) include ionic compounds in which at least one of ^Z6 and ^Z7 in formula (3) is a linear or branched divalent hydrocarbon having a hydroxyl group. Examples of such ionic compounds include ionic compounds containing pyrimidium cations as follows.

1,4-bis(2-hydroxyethyl)pyrimidinium cation, 1,5-bis(3-hydroxybutyl)pyrimidinium cation, 1-(4-hydroxybutyl)-4-(2-hydroxyethyl)pyrimidinium cation, 1,4-bis(2-hydroxyethyl)-2-methylpyrimidinium cation; and derivatives thereof.

The structure represented by formula (4) will be described below.

In formula (4), R ⁷ represents a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 or 2), and Z ⁸ to Z ¹⁰ each independently represent a structure represented by the following formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, and at least one of Z ⁸ to Z ¹⁰ represents a structure represented by the following formula (X):

The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom.
The hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 or 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups.
The structure represented by formula (4) represents an ammonium cation having at least one structure represented by the following formula (X):
There are no particular limitations on the method for incorporating the structure represented by formula (4) into the structure of a conductive resin. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (4) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the ammonium cation represented by formula (4) with an isocyanate compound.

As the ammonium cation in formula (4), ammonium cations having a straight-chain or branched structure as described in the above-mentioned column for cation structure can be used, and among these, quaternary ammonium cations are preferred.
Examples of ionic compounds having a structure corresponding to the ammonium cation in formula (4) include ionic compounds in which at least one of Z ⁸ to Z ¹⁰ in formula (4) is a linear or branched divalent hydrocarbon having a hydroxyl group. Examples of such ionic compounds include ionic compounds containing a quaternary ammonium cation listed below.

2-hydroxyethyltrimethylammonium cation, 2-hydroxyethyltriethylammonium cation, 4-hydroxybutyltrimethylammonium cation, 4-hydroxybutyl-tri-n-butylammonium cation;
bis(hydroxymethyl)dimethylammonium cation, bis(2-hydroxyethyl)dimethylammonium cation, bis(3-hydroxypropyl)dimethylammonium cation, bis(4-hydroxybutyl)dimethylammonium cation;
Tris(hydroxymethyl)methylammonium cation, tris(2-hydroxyethyl)methylammonium cation, tris(3-hydroxypropyl)methylammonium cation, tris(4-hydroxybutyl)methylammonium cation;
and their derivatives.

The structure represented by formula (5) will be described below.

In formula (5), R ⁸ and R ⁹ represent hydrocarbon groups which form a nitrogen-containing aliphatic heterocyclic structure together with the nitrogen atom to which they are bonded, Z ¹¹ to Z ¹⁴ each independently represent a structure represented by the following formula (X), a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, at least one of Z ¹¹ to Z ¹⁴ represents a structure represented by the following formula (X), and d ⁴ represents an integer of 0 to 4 (preferably 0 to 2).

The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom.
The hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 or 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups.
The structure represented by formula (5) represents a cation of a nitrogen-containing aliphatic heterocyclic structure having at least one structure represented by the following formula (X) and two nitrogen atoms. The nitrogen-containing aliphatic heterocyclic structure in formula (5) may be a five- to eight-membered ring, and is preferably a five- or six-membered ring. The nitrogen-containing aliphatic heterocyclic structure in formula (5) is preferably, for example, a piperazinium cation.
There are no particular limitations on the method for incorporating the structure represented by formula (5) into the structure of a conductive resin. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (5) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the nitrogen-containing aliphatic heterocyclic structure represented by formula (5) with an isocyanate compound.

As the nitrogen-containing aliphatic heterocyclic structure in formula (5), the cationic nitrogen-containing aliphatic heterocyclic structures described in the above section on cation structures can be used, and among these, piperazinium cations are preferred.
Examples of ionic compounds having a structure corresponding to the cation of the nitrogen-containing aliphatic heterocyclic structure in formula (5) include ionic compounds in which at least one of Z ¹¹ to Z ¹⁴ in formula (5) has a hydroxyl group and is a linear or branched divalent hydrocarbon. Examples of such ionic compounds include ionic compounds containing a piperazinium cation listed below.

1,1-bis(2-hydroxyethyl)piperazinium cation, 1,1,4-tris(2-hydroxyethyl)piperazinium cation, 1,4-bis(3-hydroxypropyl)-1-ethylpiperazinium cation, 1,4-bis(2-hydroxyethyl)-1,3-diethylpiperazinium cation; and derivatives thereof.

The structure represented by formula (6) will be described below.

In formula (6), R ⁹ represents a hydrocarbon group which forms a nitrogen-containing aliphatic heterocyclic structure together with the nitrogen atom to which it is bonded, Z ¹⁵ to Z ¹⁷ each independently represent a structure represented by formula (X), a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1), or a hydrocarbon group having 1 to 4 carbon atoms (preferably 1 to 2, more preferably 1) and a hydroxyl group, at least one of Z ¹⁵ to Z ¹⁷ represents a structure represented by the following formula (X), and d ⁵ represents an integer of 0 to 4 (preferably 0 or 1).

The hydrocarbon group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 4 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and even more preferably an alkyl group having 1 carbon atom.
The hydrocarbon group having 1 to 4 carbon atoms and a hydroxyl group is preferably a hydroxyalkyl group having 1 to 4 carbon atoms, more preferably a hydroxyalkyl group having 1 or 2 carbon atoms, and even more preferably a hydroxyalkyl group having 1 carbon atom. The hydrocarbon group may have two or more hydroxyl groups.
The structure represented by formula (6) represents a cation of a nitrogen-containing aliphatic heterocyclic structure having at least one structure represented by the following formula (X). The nitrogen-containing aliphatic heterocyclic structure in formula (6) may be a five- to eight-membered ring, and is preferably a five- or six-membered ring. The nitrogen-containing aliphatic heterocyclic structure in formula (6) is preferably, for example, a pyrrolidinium cation.
There are no particular limitations on the method for incorporating the structure represented by formula (6) into the structure of a conductive resin. For example, when the conductive resin is a urethane resin, at least one structure represented by formula (6) is incorporated into the structure of the urethane resin by reacting an ionic compound having a structure corresponding to the cation of the nitrogen-containing aliphatic heterocyclic structure represented by formula (6) with an isocyanate group.

As the nitrogen-containing aliphatic heterocyclic structure in formula (6), the cationic nitrogen-containing aliphatic heterocyclic structures described in the above section on cation structures can be used, and among these, a pyrrolidinium cation is preferred.
Examples of ionic compounds having a structure corresponding to the cation of the nitrogen-containing aliphatic heterocyclic structure in formula (6) include ionic compounds in which at least one of Z ¹⁵ to Z ¹⁷ in formula (6) has a hydroxyl group and is a linear or branched divalent hydrocarbon. Examples of such ionic compounds include ionic compounds containing a pyrrolidinium cation listed below.

1-methyl-1,2-bis(2-hydroxyethyl)pyrrolidinium cation, 1-ethyl-1,2-bis(2-hydroxyethyl)pyrrolidinium cation, 1-butyl-1,2-bis(2-hydroxyethyl)pyrrolidinium cation, 1-methyl-1,2-bis(4-hydroxybutyl)pyrrolidinium cation; and derivatives thereof.

The structure represented by formula (X) will be described below.

In formula (X), R ¹⁰ represents a linear or branched divalent hydrocarbon group, the symbol "*" represents a bond to a nitrogen atom in formulas (1) to (6) or a bond to a carbon atom in a nitrogen-containing heterocyclic structure in formulas (1) to (3) and formulas (5) to (6), and the symbol "**" represents a bond to a carbon atom in a polymer chain constituting a urethane resin having a cationic structure.
R ¹⁰ is preferably a linear or branched alkylene group having 1 to 8 carbon atoms (preferably 1 to ⁴ , more preferably 1 to 2), and may have an optional substituent such as a hydroxyl group.

When the conductive resin is a urethane resin, the structure represented by formula (X) may be formed by reacting an ionic compound having a structure corresponding to the cation in the structures represented by formulas (1) to (6) with an isocyanate compound. The isocyanate compound is preferably a urethane prepolymer obtained by reacting a polyol such as polyether polyol with an isocyanate compound. For example, polymeric MDI can be used as the isocyanate compound.

Among the structures represented by formulas (1) to (6), when the cation structure includes the structure represented by formula (1) or the structure represented by formula (2), the cation has high stability and a high dissociation rate from the counter anion. Therefore, when a lithium salt is contained as a supporting electrolyte, it is preferred because it is more likely to interact with the anion of the lithium salt, promoting dissociation of the lithium salt and improving ionic conductivity.

When the conductive resin is a urethane resin, the urethane resin preferably has a first urethane bond and a second urethane bond, and further contains a structure represented by formula (7) and a structure represented by formula (8) between the first and second urethane bonds. By containing these structures in the urethane resin, the crystallinity of the polymer main chain is suppressed even if the molecular weight between crosslinking points is large, and the inhibition of ion migration, particularly at low temperatures, is more easily suppressed. Therefore, the ionic conductivity and rate characteristics are more likely to be improved.
The method for producing such a urethane resin is not particularly limited, but it can be produced, for example, by using a polyethylene glycol-propylene glycol copolymer as a polyol and reacting it with an isocyanate compound. Alternatively, it can be produced by reacting a urethane prepolymer obtained by reacting a polyethylene glycol-propylene glycol copolymer with an isocyanate compound as the isocyanate compound with a polyol.

It is more preferable that the urethane resin contains a structure represented by the following formula (9). When the urethane resin contains the structure represented by the following formula (9), the crystallinity of the polymer main chain is suppressed, and the inhibition of lithium ion migration, particularly at low temperatures, is more easily suppressed. As a result, the ionic conductivity and rate characteristics are more likely to be improved.

In formula (9), m and n are the average number of moles added, and each independently represents a natural number of 1 or more, satisfying n≦m≦9n.
m is preferably 1 to 110, more preferably 34 to 102.
n is preferably 1 to 55, and more preferably 5 to 43.
The structure represented by formula (9) can be obtained, for example, by using a polyether polyol obtained by ring-opening polymerization of ethylene oxide and propylene oxide.
In the formula (9), the arrangement of the ethylene oxide structure represented by (-CH ₂ -CH ₂ -O-) and the propylene oxide structure represented by (-CH ₂ -CH(CH ₃ )-O-) may be a block copolymer or a random copolymer, preferably a random copolymer.

The structure of the resin can be identified by using known analytical techniques such as pyrolysis GC/MS, TF-IR, and NMR, either singly or in combination.
To identify the conductive resin in contact with the inner surface of the active material particles or the conductive resin in contact with the outer surface of the active material particles, known techniques capable of mapping the composition, interatomic bonds, crystalline structure, etc. can be used to replace or supplement the above-mentioned techniques. For example, viscoelasticity mapping using cross-sectional SPM, element mapping using TOF-SIMS, carbon-carbon bond mapping using FT-IR or Raman, and soft tissue structural mapping using a soft X-ray microscope can be used. For the soft X-ray microscope, an inspection device attached to a synchrotron radiation facility such as SPring-8 can be used.

(anionic structure)
Examples of anions that the conductive resin preferably contains include a fluoroalkylsulfonylimide anion, a fluorosulfonylimide anion, a fluoroalkylsulfonate anion, a fluorosulfonate anion, a fluoroalkylcarboxylate anion, a fluoroalkylmethide anion, a fluoroborate anion, a fluorophosphate anion, a dicyanamide anion, a thiocyanate anion, a bisoxalatoborate anion, a perchlorate anion, and derivatives thereof.

Specific examples of fluoroalkylsulfonylimide anions include fluoroalkylsulfonylimide anions having a fluoroalkyl group having from 1 to 6 carbon atoms, such as bis(trifluoromethanesulfonyl)imide anion, bis(pentafluoroethanesulfonyl)imide anion, bis(heptafluoropropanesulfonyl)imide anion, bis(nonafluorobutanesulfonyl)imide anion, bis(dodecafluoropentanesulfonyl)imide anion, and bis(perfluorohexanesulfonyl)imide anion, as well as cyclic fluoroalkylsulfonylimide anions such as N,N-hexafluoropropane-1,3-disulfonylimide.

A specific example of the fluorosulfonylimide anion is a bis(fluorosulfonyl)imide anion.
Specific examples of the fluoroalkylsulfonate anion include trifluoromethanesulfonate anion, fluoromethanesulfonate anion, perfluoroethanesulfonate anion, perfluoropropanesulfonate anion, perfluorobutanesulfonate anion, perfluoropentanesulfonate anion, perfluorohexanesulfonate anion, and perfluorooctanesulfonate anion.
Specific examples of the fluoroalkyl carboxylate anion include a trifluoroacetate anion, a perfluoropropionate anion, a perfluorobutyrate anion, a perfluorovalerate anion, and a perfluorocaproate anion.
Specific examples of the fluoroalkyl methide anion include fluorinated alkylsulfonyl methide anions such as tris(trifluoromethanesulfonyl)methide anion, tris(perfluoroethanesulfonyl)methide anion, tris(perfluoropropanesulfonyl)methide anion, tris(perfluorobutanesulfonyl)methide anion, tris(perfluoropentanesulfonyl)methide anion, tris(perfluorohexanesulfonyl)methide anion, and tris(perfluorooctanesulfonyl)methide anion.

A specific example of the fluoroborate anion is tetrafluoroborate anion.
A specific example of the fluorophosphate anion is hexafluorophosphate anion.

Among these anions, at least one selected from the group consisting of fluoroalkylsulfonylimide anion, fluorosulfonylimide anion, fluoroborate anion, dicyanamide anion, and thiocyanate anion is particularly preferred because it reduces the decrease in conductivity in low-temperature environments.

The conductive resin preferably has greater flexibility than the active material particles. When the conductive resin has greater flexibility than the active material particles, it is more likely to change shape in response to the expansion and contraction of the active material particles during charging and discharging. As a result, it becomes easier to prevent a decrease in ionic conductivity and electronic conductivity. Whether the conductive resin has greater flexibility than the active material particles can be confirmed by measuring the Young's modulus using a commercially available device such as a nanoindenter.

The conductive aid is not particularly limited, and examples that can be used include graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, carbon fluoride powder, conductive fibers such as carbon fiber, carbon nanotube, and metal fiber, metal powders such as gold, platinum, silver, and aluminum, conductive whiskers such as zinc oxide, conductive metal oxides such as titanium oxide, and organic conductive materials such as phenylene dielectrics.

The supporting electrolyte is not particularly limited, and for example, a conductive resin can be used as an organic electrolyte, and an inorganic electrolyte such as a lithium salt can also be used.
Furthermore, ion-conductive solids typically used in all-solid-state batteries can be used. Examples include Li-B oxide-based solid electrolyte particles, Li-Yb oxide-based solid electrolyte particles, Nasicon-type solid electrolyte particles (LiAlTi(PO ₄ ) ₃ , LiAlGe(PO ₄ ) ₃ , etc.), and Li-P-O-based solid electrolyte particles (Li ₃ PO ₄ , LiPON (particles in which some of the O in Li ₃ PO ₄ is replaced with N)). Among the above solid electrolyte particles, Li-B oxide-based solid electrolyte particles and Li-Yb oxide-based solid electrolyte particles can be sintered at relatively low temperatures (700°C or less), thereby suppressing reaction with the positive electrode active material particles during sintering and maintaining ion conductivity. For this reason, among the above solid electrolyte particles, it is preferable to include Li-B oxide-based solid electrolyte particles and Li-Yb oxide-based solid electrolyte particles.

The supporting electrolyte is more preferably a lithium salt, such as at least one selected from _the group consisting of LiClO4, _LiBF4 , _LiPF6 , _LiAlCl4 , _LiSbF6 , _LiSCN , _LiCF3SO3 , _LiAsF6 , lower aliphatic lithium carboxylates, LiCl, LiBr, LiI, lithium chloroborane, _lithium tetraphenylborate, LiN( _CF3SO3 ) ₃ , _and LiN( _C2F5SO2 ) _{2 .}
Among these, at least one selected from _the group consisting of LiN( _CF3SO3 ) ₃ , _LiN ( _C2F5SO2 ) _{2 ,} and _LiClO4 is preferred. These lithium salts have high chemical stability with respect to lithium-based active materials, and are less likely to produce an insulating coating at the negative electrode interface due to decomposition of the lithium salt. Therefore, the resistance at the negative electrode interface is less likely to fluctuate. The lithium salts can be used alone or in combination of two or more.

The content of the supporting electrolyte is preferably 0.8 to 40.0 parts by mass, more preferably 5.0 to 40.0 parts by mass, even more preferably 5.0 to 15.0 parts by mass, and particularly preferably 5.0 to 10.0 parts by mass, relative to 100 parts by mass of the conductive resin. When the content of the supporting electrolyte is within this range, the supporting electrolyte is easily miscible with the conductive resin, does not precipitate even at low temperatures, and high ionic conductivity is obtained.
The type and content of the indicator electrolyte contained in the conductive resin can be measured by solvent extraction followed by LC-MS or the like.

The solid electrolyte particles may be commercially available products or may be separately prepared as materials.
Examples of Li-B oxide solid electrolyte particles that can be used include Li ₃ BO ₃ (manufactured by Toshima Manufacturing Co., Ltd.) and particles in which part of the O in Li ₃ BO ₃ is substituted with C. Examples of Li-Yb oxide solid electrolyte particles that can be used include Li _5.9 Yb _0.81 La _0.09 Zr _0.1 (BO ₃ ) ₃ .

In the case of an electrode containing an inorganic electrolyte between active material particles, it is preferable that the region between the active material particles containing the conductive resin overlaps with the region between the active material particles containing the inorganic electrolyte. This overlap between the active material particles between the region between the active material particles containing the conductive resin and the region between the active material particles is also referred to as the conductive resin and the inorganic electrolyte being coexisting unevenly. It is more preferable that the region containing the conductive resin includes a region containing the inorganic electrolyte.
The above-described relationship between the conductive resin and the inorganic electrolyte has the effect of reducing the interfacial resistance between the inorganic electrolyte solid electrolyte particles. Although solid electrolytes (bulk) generally have better ionic conductivity than conductive resins, they are prone to a decrease in conductivity due to interfacial resistance between the solid electrolyte particles. The overlap of the conductive resin with the region containing the solid electrolyte particles facilitates the realization of a low-resistance electrode without significantly reducing the high ionic conductivity of the solid electrolyte (bulk). Furthermore, the above-described relationship can be confirmed by the results of elemental mapping in cross-sectional observations, as described below.

<Method of manufacturing electrode precursor>
An example of a method for manufacturing an electrode precursor will be described in detail below with reference to the drawings. Hereinafter, the electrode precursor can be made into a positive electrode precursor by using positive electrode active material particles as the active material particles. Also, the electrode precursor can be made into a negative electrode precursor by using negative electrode active material particles as the active material particles.

The method for producing an electrode precursor according to the present disclosure preferably includes the following four steps (step 1, step 2, step 3, and step 4): Fig. 1 is a conceptual diagram showing the method for producing an electrode precursor.
(1) A first step of forming a particle layer containing active material particles and electrolyte particles on a resin substrate having an adhesive portion (S101 in FIG. 1 ).
(2) A second step (S102 in FIG. 1 ) of forming a laminate by laminating a plurality of resin substrates (hereinafter also referred to as substrates) on which the particle layer has been formed.
(3) A third step (S103 in FIG. 1 ) of removing the resin substrate from the laminate and forming a three-dimensional object containing active material particles and electrolyte particles.
(4) A fourth step of post-processing the three-dimensional object (S104 in FIG. 1).

(1st step)
The first step is to form a particle layer containing active material particles and electrolyte particles on a resin substrate having an adhesive portion. In the first step, particles are arranged on the resin substrate using a particle arrangement device, thereby forming the particle layer. Hereinafter, particle arrangement devices 1 and 2 that can be used will be described in order.

[Particle arrangement device 1]
2 is a diagram schematically illustrating the configuration of the particle arrangement device 1. Hereinafter, first particles P1 refer to the above-described active material particles, and second particles P2 refer to the above-described electrolyte particles.
The particle placement device 1 has a first storage container 21a that stores and supplies a first base material 11a, a first belt device 22a that transports the first base material 11a, and a pattern forming device 23 that forms a concave-convex pattern on the first base material 11a. The particle placement device 1 has a first filling device 24a that places first particles P1 in the concave portions of the concave-convex pattern formed on the first base material 11a.
The particle arrangement device 1 has a second storage container 21b that stores and supplies the second substrate 11b and a second belt device 22b that transports the second substrate 11b. The particle arrangement device 1 has a transfer unit 25a in which rollers 223a and 223b of the first belt device 22a and the second belt device 22b, respectively, face each other, and the first particles P1 are transferred from the first substrate 11a to the second substrate 11b in the transfer unit 25a.

Furthermore, the particle placement device 1 has a second filling device 24b that places second particles P2 in the non-transfer area on the second substrate 11b. Note that devices that are less relevant to explaining the effects of this invention, such as a peeling and recovery device that peels and recovers the first substrate 11a from the first belt device 22a after transfer, and various cleaning devices, are not shown or described in detail.

In the particle placement device 1, the pattern forming device 23, the first filling device 24a, and the transfer unit 25a can be considered as a first placement unit that places the first particles P1 in a pattern on the resin substrate that is the second substrate 11b. Also, the second filling device 24b can be considered as a second placement unit that places the second particles P2 in areas on the resin substrate that is the second substrate 11b where the first particles P1 are not placed.

Hereinafter, a method for arranging particles on substrate 11 using particle arrangement device 1 will be described along the flow of each process.
First, the first substrate 11a is supplied from the first storage container 21a to the first belt device 22a by a supply means (not shown).
When a UV-curable liquid is applied by a pattern forming device 23 (described later), it is preferable that at least the surface of the first substrate 11a is made of a material that has high wettability with the UV-curable liquid. In addition, it is preferable that the surface of the first substrate 11a is smooth.

The first substrate 11a can be a sheet made of a resin such as polyester that has been treated to be hydrophilic or lipophilic to match the UV-curable liquid (water-based or oil-based) to be used. The first substrate 11a may be a substrate that is individually cut out like cut paper, a continuous substrate wound into a roll like roll paper, or a continuous substrate that is alternately folded like continuous paper.

The first belt device 22a transports the supplied first substrate 11a to the pattern formation position of the pattern forming device 23. The first belt device 22a has drive rollers 221a and 222a, a pressure roller 223a, and a belt-like transport member 224a suspended between them. At this time, the pressure roller 223a rotates driven by the drive rollers.

The conveying member 224a is preferably made of a material selected from resin or metal, and for example, a polyimide resin belt can be used. The drive rollers 221a and 222a are preferably made of metal, and for example, stainless steel metal rollers can be used. The pressure roller 223a is preferably made of a soft roller with an elastic surface layer, and for example, a soft roller with an elastic silicone rubber layer on the surface of a stainless steel core can be used.

In Figure 2, a first belt device 22a is used as the conveying device for conveying the first substrate 11a, but a roller device can also be used instead of the belt device. The same applies to the second belt device 22b described below.

The pattern forming device 23 forms a fine concave-convex pattern on the first substrate 11a that has been transported to the pattern forming position. Methods that can be used to form the concave-convex pattern include UV imprinting, thermal imprinting, UV inkjet printing, printing, and laser etching.

When the pattern forming device 23 forms a concave-convex pattern using a UV imprint method, the pattern forming device 23 has a coating means for coating the first substrate 11a with a UV-curable liquid. The UV-curable liquid can be, for example, a UV-curable resin such as UV-curable liquid silicone rubber. The pattern forming device 23 also has an imprinting means for imprinting a mold having a concave-convex pattern formed on its surface onto the UV-curable liquid on the first substrate 11a, and a light source for irradiating the UV-curable liquid with UV rays. Typically, UV-curable liquid silicone rubber (PDMS) or resin is used as the UV-curable liquid, a film mold is used as the mold, and a UV lamp is used as the light source.

The first filling device 24a fills the first particles P1 with the support material S1 carrying the first particles P1.
When P1 is filled into the recesses on the first substrate 11a, the opening diameter (width) of the recesses in the concave-convex pattern on the first substrate 11a is preferably larger than the cumulative 50% particle diameter (median diameter) on a volume basis of the first particles P1. The opening diameter (width) of the recesses is preferably smaller than the average size of the support material S1. Here, the opening diameter of the recesses in the concave-convex pattern is preferably the opening diameter in the short-side direction of the recesses, and more preferably the maximum opening diameter in the short-side direction of the recesses.
The width of the recess can be adjusted appropriately depending on the particle sizes of the first particles P1 and the support material S1, etc. The width of the recess is not particularly limited, but is preferably 0.2 to 30 μm, and more preferably 2 to 15 μm, for example.

By setting the opening diameter of the recesses of the uneven pattern as described above, the first particles P1 can come into contact with the bottoms and side surfaces (typically the bottom surfaces) of the recesses of the uneven pattern. On the other hand, the support material S1 cannot come into contact with the bottoms and side surfaces of the recesses. This allows the uneven pattern to capture the first particles P1 that come into contact with the bottoms and side surfaces of the recesses, while preventing the support material S1 from being captured by the uneven pattern. In other words, it is preferable that the first particles P1 can come into contact with the bottoms and side surfaces of the recesses of the uneven pattern, but the first support material S1 cannot come into contact with the bottoms and side surfaces of the recesses of the uneven pattern.

The pattern forming device 23 forms a concave-convex pattern on the first substrate 11a, but a substrate with a concave-convex pattern pre-formed on its surface may also be used as the first substrate 11a. Alternatively, the pattern forming device 23 may form a concave-convex pattern directly on the surface of the conveying member 224a of the first belt device 22a, or a conveying member having a concave-convex pattern on its surface may be used as the conveying member 224a. In this case, in consideration of durability, it is preferable to use a metal belt made of stainless steel, aluminum, or the like, and form the concave-convex pattern on the surface using microfabrication techniques such as laser etching, wet etching, or dry etching.

The first base material 11a having the concave-convex pattern formed on its surface is transported by the first belt device 22a to the filling position of the first filling device 24a.
3 is a diagram showing a schematic configuration of the filling device. The configuration of the first filling device 24a will be described below, but the second filling device 24b has the same configuration.

The first filling device 24a has a filling container 242a that contains filler 241a, a stirring screw member 243a that stirs and transports the filler 241a, a recovery member 244a that recovers the filler, and a magnetic member 247a.

The filler 241a has first particles P1 and a support material S1 that supports the first particles P1. The filler 241a is a mixture of multiple powders, including a powder composed of multiple first particles P1 and a powder composed of multiple support materials S1. The filler 241a contained in the filling container 242a is thoroughly mixed when stirred and transported by the stirring screw member 243a. As a result, the first particles P1 are supported on the surface of the support material S1. The forces acting between the particles when they are supported include electrostatic forces due to frictional charging, van der Waals forces, liquid bridging forces, etc.

The support material S1 is a magnetic particle. The support material S1 is preferably a particle in which the surface of a resin particle in which ferrite core particles or a magnetic material is dispersed is coated with a resin composition. For example, a standard carrier (Standard Carrier P02 manufactured by the Imaging Society of Japan), which is a magnetic particle, can be used. The particle size and material of the support material S1 are appropriately selected according to the particle size and material of the first particles P1. This allows the first particles P1 to be stably supported. Furthermore, even if the first particles P1 have a small particle size and tend to aggregate, the support material S1 plays a role in loosening the particles by stirring and transporting them with the support material S1.
The particle size of the support material S1 can be adjusted appropriately by adjusting the size (area, width, depth) of the recesses. For example, the cumulative 50% particle size (median diameter) on a volume basis is preferably 50 to 100 μm.

The recovery member 244a has a roller 245a that can rotate in the direction of arrow d2 in the figure, and a magnet 246a that is disposed inside the roller 245a and fixed to the filling container 242a. The magnetic member 247a is disposed opposite the filling container 242a via the conveying member 224a, and has a magnet 248a inside.

Magnet 246a has a plurality of N and S poles arranged alternately along the rotation direction of collection member 244a. Magnet 248a has a plurality of N and S poles arranged alternately along the transport direction of transport member 224a. Magnet 246a also has a magnetic pole (N1 pole in FIG. 3) of a different polarity at a position closest to and facing the most downstream magnetic pole (S1 pole in FIG. 3) of magnet 248a, and an N2 pole of the same polarity as N1 pole is arranged at the most downstream position.
The magnet 246a and the magnet 248a may be composed of a plurality of magnets, and the type of magnet constituting the magnet 246a and the magnet 248a is not particularly limited. For example, a permanent magnet such as a rare earth magnet, a ferrite magnet, a neodymium magnet, or a samarium-cobalt magnet, or a plastic magnet, or a means for generating a magnetic field such as an electromagnet can be used. The magnet 248a may be configured to be movable in the transport direction of the first substrate 11a or in the opposite direction.

In addition, a regulating member for regulating the filler 241a on the first substrate 11a, or a recovery member for re-recovering filler 241a that cannot be recovered by the recovery member 244a, may be provided upstream or downstream of the recovery member 244a in the transport direction of the transport member 224a. The recovery member for re-recovery may be a member similar to the recovery member 244a, or may be a simple member such as a fixed magnet or a regulating member, or a recovery member that recovers by air blowing.

Next, the process of filling the recesses on the first substrate 11a with the first particles P1 by the first filling device 24a will be described with reference to FIGS.
As the first conveying member 224a moves in the direction of the solid arrow d1 in Figure 3, the first substrate 11a carried and conveyed by the first conveying member 224a is conveyed and transported to the filling position of the first filling device 24a.

The filler 241a is transported by the stirring screw member 243a and supplied onto the first substrate 11a (dotted line a in Figure 3). At this time, a magnetic field is formed by the magnetic member 247a and the recovery member 244a, and the filler 241a containing the magnetic particle carrier material S1 forms multiple magnetic chains on the first substrate 11a due to this magnetic field. As the first substrate 11a moves, the filler 241a supplied onto the first substrate 11a is transported over the first substrate 11a while forming magnetic chains (dotted line b in Figure 3).

Figures 4A, 4B, and 4C are schematic diagrams of filler 241a being transported on the first substrate 11a. For the sake of explanation, filler 241a other than the filler forming a single magnetic strand is not shown. As described above, the filler 241a on the first substrate 11a forms magnetic strands along the magnetic field lines of the generated magnetic field, and is transported while changing the shape of the magnetic strands as the first substrate 11a moves, as shown in Figures 4A, 4B, and 4C. At this time, a particularly strong magnetic force acts near the magnet 248a, so the transport speed v2 of filler 241a is smaller than the movement speed v1 of the first substrate 11a when filler 241a moves away from the magnetic pole, and is larger in the opposite case. In other words, the filler 241a on the first substrate 11a has a non-zero relative speed with respect to the first substrate 11a.

5 is an enlarged view of the vicinity of the surface of the first base material 11a in FIGS. 4A to 4C. Although not shown in FIGS. 4A to 4C, as shown in FIG. 5, the first base material 11a has a concave-convex pattern 1.
The concave-convex pattern can be formed as a desired pattern such as a honeycomb pattern or a line pattern.
The filler 241a comes into contact with the concave-convex pattern 111a, and is transported together with the first substrate 11a at a non-zero relative speed with respect to the first substrate 11a while being subjected to a magnetic force (solid line Fm in the figure) in a direction perpendicular to the surface of the first substrate 11a. As a result, the first particles P1 carried on the support material S1 are transported while being rubbed against the concave-convex pattern 111a on the surface of the first substrate 11a.

At this time, the particle size of the first particles P1 is smaller than the opening diameter of the recesses in the uneven pattern 111a, and the particle size of the first support material S1 is larger than the opening diameter of the recesses. Therefore, the first particles P1 can come into contact with the bottom surfaces (bases) and side surfaces of the recesses in the uneven pattern 111a, but the support material S1 cannot. In other words, only the first particles P1 in the filler 241a selectively come into contact with the bottom surfaces and side surfaces of the recesses.

The first particles P1 that come into contact with the recesses are strongly restrained by the physical restraining force due to the structure of the uneven pattern 111a, and by non-electrostatic adhesive forces such as electrostatic adhesion and adhesive forces with the structural materials that make up the first substrate 11a and the uneven pattern 111a, and are detached from the support material S1. Note that for the sake of explanation, Figure 5 shows the first particles P1 supported on the surface of the support material S1, but it is acceptable for particles P1 that are not supported on the support material S1 to exist during the agitation, supply, or transport of the filler 241a.

As shown in Figure 3, downstream of the magnetic member 247a, the recovery member 244a is positioned with a gap between it and the first transport member 224a. As the first substrate 11a moves, the filler 241a is transported near the most downstream magnetic pole (S1 pole) of the magnet 248a. Under the influence of the magnetic field formed by the magnet 246a, the filler 241a moves from the first substrate 11a to the recovery member 244a and is recovered (dotted line c in Figure 3).

As described above, during the transport process (dotted lines a, b, and c in Figure 3), the recesses of the uneven pattern 111a on the surface of the first substrate 11a come into sufficient contact with the plurality of fillers 241a. Therefore, after the fillers 241a have been collected by the collection member 244a, the first particles P1 are selectively and densely arranged in the recesses of the uneven pattern 111a.

Note that while Figures 4A-4C and 5 show the first particles P1 all having the same particle size, in reality there is a particle size distribution, and depending on the material, they may form agglomerated secondary particles. They may also not have the spherical shape shown. Even in such cases, only particles that can come into contact with the recesses of the uneven pattern 111a are selectively and densely packed, so coarse powder and secondary particles that could adversely affect the particle placement process are easily excluded.

In this way, the amount of the first particles P1 filling the recesses of the concave-convex pattern 111a can be controlled by the size (area, width, depth) of the concave-convex pattern and the particle size of the first particles P1. Specifically, the area of the recesses is approximately the filling area, and the layer thickness of the filled first particles P1 is determined by the depth of the recesses.
The pitch of the convex portions is not particularly limited, but is preferably, for example, 1.0 to 20 μm, and more preferably 2.0 to 15 μm.
The height of the convex portions is not particularly limited, but is preferably, for example, 0.1 to 20.0 μm, and more preferably 1.0 to 10.0 μm.
The area ratio of the recesses (the ratio of the recesses to the area of the recessed/protruding pattern) is not particularly limited, but is preferably, for example, 50% or more, and more preferably 70% or more.

For example, to obtain a thin layer (single layer) that accounts for 50% of the area of the substrate, the area ratio of the recesses (the area ratio of the recesses to the entire concave-convex pattern) should be 50%, and the depth of the recesses should be equal to or less than the particle size of the first particles P1. In this case, the opening width of the recesses should be larger than the median diameter of the first particles P1 and smaller than the average size (here, the average particle size) of the support material S1.

Note that while the first particles P1 may have a wide particle size distribution (broad particle size distribution), the support material S1 preferably has a narrow particle size distribution, and is more preferably monodisperse. This makes it easier to prevent the support material S1 from coming into contact with the bottom (or bottom surface) or side surfaces of the recess. If the support material S1 is able to come into contact with the bottom or side surfaces of the recess, the support material S1 may also be restrained and filled into the recess.

Furthermore, the opening width of the recesses of the concave-convex pattern 111a is preferably smaller than four times the particle diameter of the first particles P1. By making the opening width smaller than four times the particle diameter of the first particles P1, the probability that the first particles P1 will come into contact with two points, the bottom and side surfaces of the recesses of the concave-convex pattern 111a, can be increased. In this way, the first particles P1 that come into multi-point contact with the concave-convex pattern 111a are strongly constrained by the concave-convex pattern 111a, thereby increasing the efficiency of filling the concave-convex pattern 111a with the first particles P1.
The same applies to the particle size of the second particles P2 described later and the size of the recesses of the uneven pattern formed by the first particles P1 on the second substrate. Furthermore, when brush fibers are used as the support material, the "average particle size of the support material" in the above description becomes the "average fiber diameter of the support material."

The filler 241a collected by the collection member 244a is transported by the rotating collection member, roller 244a (dotted line d in Figure 3). The filler 241a transported by roller 244a falls into filling container 242a (dotted line e in Figure 3) due to the magnetic field created by two adjacent, repelling magnetic poles of the same polarity (N1, N2) and the influence of gravity. It is then stirred and transported again by stirring screw member 243a, and this process is repeated thereafter.

The weight ratio of the first particles P1 to the support material S1 in the filler 241a in the filling container 242a is determined by an inductance sensor that measures magnetic permeability, a patch density sensor that measures and predicts the reflection density on a substrate, or the like, which are common in electrophotographic devices. At least one of the first particles P1 and the support material S1 is replenished by a replenishment means (not shown) as needed. This allows stable filling over a long period of time.
The mass % of the first particles P1 in the filler 241a is not particularly limited, but is preferably in the range of 5 to 40 mass %, or 10 to 30 mass %.

Note that while we have described a filling device that uses magnetic particles as a carrier material to form a so-called magnetic brush, filling recesses with particulate material, the filling device's method is not limited to this. Brush fibers can also be used as the carrier material. Alternatively, an elastic material, at least the surface of which is made of an elastic body, can also be used as the carrier material.

FIG. 6A is a diagram schematically illustrating the configuration of a filling device 24c when brush fibers are used as the support material.
The filling device 24c has a roller 2410 with brush fibers on its surface. The roller 2410 is a so-called brush roller, with brush fibers planted on its surface. The brush fibers of the roller 2410 may be made of a material such as nylon, rayon, acrylic, vinylon, polyester, or vinyl chloride. The surface of the fibers may be subjected to a surface treatment in order to adjust the electrostatic charge property or rigidity.

The filling device 24c has a supply member that supplies the filler 241a to the roller 2410. The filler 241a contains powder including the first particles P1 and is stored in a filling container 242a. In this example, the filler 241a does not contain the carrier material S1, which is a magnetic particle. The filler 241a is stirred and transported by a stirring screw member 243a and supplied to a supply member 249.

The supply member 249 supplies the filler 241a to the roller 2410, and its configuration is not particularly limited. For example, the supply member 249 can be a roller whose surface is made of an elastic, porous foam material. A typical example is an elastic sponge roller with a foamed skeletal structure, in which a relatively low-hardness polyurethane foam is formed on a core metal. In addition to urethane, various rubber materials such as nitrile rubber, silicone rubber, acrylic rubber, hydrin rubber, and ethylene propylene rubber can also be used as the foam material.

The supplied filler 241a fills the foam material on the surface of the supply member 249 and is transported to the supply section that comes into contact with the roller 2410. In the supply section, the filler 241a filled into the foam material becomes charged by contact with the brush fibers of the roller 2410 and is carried by the brush fibers of the roller 2410. Furthermore, the supply member 249 may also have the function of peeling off and refreshing any filler 241a remaining on the roller 2410. The filler 241a supplied to the roller 2410 comes into contact with the first substrate 11a as the brush fibers move.

At this time, the first particles P1 in the filler 241a can come into contact with the bottom and side surfaces of the recesses in the uneven pattern 111a on the surface of the first substrate 11a, but the brush fibers cannot. In other words, the fiber diameter of the brush fibers is made larger than the opening width of the recesses in the uneven pattern 111a. The fiber diameter of the brush fibers can be measured by placing glass on the surface of the roller 2410 and taking an image of the brush fibers through the glass using an optical microscope. At this time, the fiber diameters of approximately 100 brush fibers are measured, the fiber diameter distribution is measured, and the average diameter is calculated.

The movement of the conveying member 224a and the rotation of the roller 2410 causes the brush fibers of the roller 2410 to rub against the surface of the first substrate 11a. As a result, the first particles carried by the brush fibers are densely arranged in the recesses of the uneven pattern 111a on the surface of the first substrate 11a.

FIG. 6B is a diagram showing a schematic configuration of a filling device 24d when an elastic material is used as the support material.
The filling device 24d has a similar configuration to the filling device 24c, but differs in that a roller 2411 having an elastic material is used instead of the roller 2410 having brush fibers. The roller 2411 is a roller having an elastic layer formed on its surface.

The elastic layer is formed of an elastic material such as a rubber material such as silicone rubber, acrylic rubber, nitrile rubber, urethane rubber, fluororubber, etc. The surface shape of the elastic layer may be controlled by adding fine particles such as spherical resin.
When the elastic layer has convex portions on its surface, the size of the convex portions of the elastic layer is set to be larger than the size of the concave portions of the concave-convex pattern 111 a. The size of the convex portions of the elastic layer can be measured in the same manner as the fiber diameter of the brush fibers described above.

As the conveying member 224a moves and the roller 2411 rotates, the elastic material on the surface of the roller 2411 rubs against the surface of the first substrate 11a. As a result, the first particles carried by the elastic material are densely arranged in the recesses of the uneven pattern 111a on the surface of the first substrate 11a.

Using brush fibers or elastic material as the carrier material, as in Figures 6A and 6B, eliminates the need to include magnetic particles in the filler. This also simplifies the configuration of the filling device. On the other hand, when magnetic particles are used as the carrier material, as in Figure 3, there is greater freedom in the size and shape of the carrier material than when using brush fibers or elastic material. Furthermore, magnetic particles allow greater freedom in the movement of the carrier material on the substrate.

For these reasons, when magnetic particles are used as the support material, particles such as the first particles P1 can be supplied more efficiently onto the substrate, allowing for more efficient filling of recesses on the substrate. Furthermore, when a magnetic material is used as the support material, even if the support material deteriorates during the process, it can be replenished or replaced without stopping the process.

The method of filling recesses with particles by rubbing a support material carrying the particles allows for a larger amount of dispersed particles to be supplied to the recesses, resulting in more stable and dense filling, compared to filling methods using a restricting member such as a blade. This advantage is more pronounced the smaller the particle size of the particles being filled, as the particles tend to agglomerate more easily.

The first base material 11a, in which the first particles 1 have been filled into the recesses of the concave-convex pattern 111a by the first filling device 24a, is transported to the transfer section 25a by the first belt device 22a.
2, the second belt device 22b, like the first belt device 22a, has drive rollers 221b and 222b, a pressure roller 223b, and a belt-like conveying member 224b suspended between them. At this time, the pressure roller 223b is driven to rotate. At the transfer section 25a, the pressure roller 223a of the first belt device 22a and the pressure roller 223b of the second belt device 22b face each other.

The second substrate 11b is supplied to the second belt device 22b from the second storage container 21b and transported in the direction of the arrow in Figure 2. The supplied second substrate 11b is transported in accordance with the timing at which the first substrate 11a is transported to the transfer unit 25a. At the transfer unit 25a, the first particles P1 filled in the first substrate 11a are transferred to the second substrate 11b.

In other words, the first substrate 11a can also be referred to as a transfer substrate for transferring the first particles P1 to the second substrate 11b. The concave-convex pattern formed on the surface of the first substrate 11a can also be referred to as a transfer concave-convex pattern. This transfer process will be described below with reference to Figure 7.

Figure 7 is a diagram showing a schematic configuration of the transfer unit 25a. The transfer unit 25a is composed of the pressure roller 223a and conveying member 224a of the first belt device 22a, and the pressure roller 223b and conveying member 224b of the second belt device 22b. As described above, the pressure rollers 223a and 223b rotate drivenly, and the two rollers are in contact via the conveying members 224a and 224b. At least one of the pressure rollers 223a and 223b is a soft roller with an elastic layer on its surface, and a nip is formed where the two rollers come into contact.

The first substrate 11a, filled with the first particles P1 by the first filling device 24a, and the second substrate 11b are transported at approximately the same speed by their respective transport members (224a, 224b) and enter the nip formed by the contact of the pressure rollers 223a, 223b. In the nip, the first particles P1 on the first substrate 11a come into contact with the second substrate 11b and are transferred onto the second substrate 11b.

The second substrate 11b has a stronger adhesive force to the first particles P1 than the first substrate 11a has to the first particles P1. In other words, the adhesive force of the first particles P1 to the second substrate 11b is stronger than the adhesive force of the first particles P1 to the first substrate 11a. As a result, the first particles P1 on the first substrate 11a are transferred to the second substrate 11b at the nip portion.

The material of the second substrate 11b is not particularly limited, and a substrate of the same material as the first substrate 11a can be used. Like the first substrate 11a, the second substrate 11b may be a substrate that is individually cut like cut paper, a continuous substrate wound into a roll like roll paper, or a continuous substrate that is alternately folded like continuous paper.

The second substrate 11b is preferably surface-treated to enhance adhesion so that it can transfer the first particles P1 that come into contact with it. For example, the second substrate 11b preferably has an adhesive portion on its surface where an adhesive is applied. As a preparation step for preparing a resin substrate with an adhesive portion, for example, the second substrate 11b is prepared. There are no particular restrictions on the thickness of the second substrate, but it is preferably 1 to 10 μm, for example. There are also no particular restrictions on the thickness of the adhesive portion, but it is preferably 0.1 μm or more, and more preferably 0.5 μm or more.

Furthermore, it is preferable that the back surface of the second substrate 11b (the surface to which the first particles P1 are not transferred) also has an adhesive portion coated with the same adhesive as the front surface, and that this surface is further covered with a protective film or the like. This prevents misalignment between the substrates during stacking, as described below, and firmly fixes the active material particles and electrolyte particles between the substrates by sandwiching them between the top and bottom surfaces (stacking direction). This prevents particle movement during stacking, storage of the stack, heat treatment, and pressure application, allowing the desired electrode precursor to be formed.

The adhesive is not particularly limited, and may be an acrylic adhesive, a rubber adhesive, a silicone adhesive, or a thermoplastic resin or a photocurable resin whose adhesive strength changes in response to disturbances such as heat or light. The particle arrangement device 1 may also have application means such as a dispenser or an inkjet head that applies adhesive to the surface of the second substrate 11b during transport.
The type and amount of adhesive to be applied are adjusted as appropriate depending on the shape and material of the concave-convex pattern to be used, the particle size and material of the first particles P1 and the second particles P2, etc., but it is preferable that the adhesive strength be greater than that of the concave-convex pattern 111 a. The comparison of adhesive strength can be measured by a general method using a nanoindenter.

At the nip, the first particles P1 are restrained by the adhesive force generated between them and the second substrate 11b. When the conveying members 224a, 224b separate after passing through the nip, the first particles P1 that were on the first substrate 11a are transferred to the second substrate 11b.

The second substrate 11b onto which the first particles P1 have been transferred is transported by the transport member 224b to the loading position of the second loading device 24b.
The second filling device 24b has the same configuration and function as the first filling device 24a, except that a filling container 242a contains a filler 241b having second particles P2 and a carrier material S2 instead of a filler 241a having first particles P1 and a carrier material S1.

The second filling device 24b fills the second particles P2 into the portions of the second substrate 11b where the first particles P1 are not placed. As described above, the first particles P1 are placed on the second substrate 11b that has passed through the transfer unit 25a, but the adhesive portions are exposed in the portions where the first particles P1 are not placed, forming recesses, so to speak. The second filling device 24b fills the recesses (adhesive portions) with the second particles P2 using the same process as the first filling device 24a.

In this way, the second particles P2 that can be filled are selectively filled into gaps on the second substrate 11b where the first particles P1 are not placed, thereby improving the coverage rate of the substrate by the particles.
The second particles P2 preferably have a median diameter equal to or smaller than the opening width of the gaps between the first particles P1. Note that although the case where magnetic particles are used as the carrier material will be described here, brush fibers or elastic materials may also be used as the carrier material, as in the first filling device 24a.

The filler 241b includes second particles P2 and a support material S2 that supports the second particles P2. The filler 241b is a mixture of multiple powders including a powder composed of multiple second particles P2 and a powder composed of multiple support materials S2. The support material S2 may be the same as or different from the support material S1. The support material S2 is selected appropriately depending on the particle size and material of the second particles P2 and the opening width of the voids described above.
The mass % of the second particles P2 in the filler 241b is not particularly limited, but is preferably in the range of 5 to 40 mass %, or 10 to 30 mass %.

Figure 8 is an enlarged view of the surface vicinity of the second substrate 11b during the filling process using the second filling device 24b. A concave-convex pattern is formed on the second substrate 11b, with convex portions formed by the placement of the first particles P1 and concave portions where the first particles P1 are not placed. The adhesive portions 13b are exposed in the concave portions on the second substrate 11b where the first particles P1 are not placed. During the filling process using the second filling device 24b, the second particles P2 are placed on the adhesive portions 13b on the surface of the second substrate 11b. After the filling process using the second filling device 24b, the first particles P1 and the second particles P2 are arranged adjacent to each other on the surface of the adhesive portion of the second substrate 11b. In other words, by placing the second particles P2 in the portions of the second substrate 11b where the first particles P1 are not arranged, the first particles P1 and the second particles P2 can be arranged adjacent to each other. Furthermore, it is not necessary for the second particles P2 to be arranged adjacent to all of the first particles P1; first particles P1 or second particles P2 may be adjacent to each other.

The filler 241b comes into contact with this uneven pattern and is subjected to a magnetic force (solid line Fm in the figure) perpendicular to the surface of the second substrate 11b. It is transported along with the second substrate 11b at a non-zero relative speed with respect to the second substrate 11b. As a result, the second particles P2 carried by the carrier material S2 are transported while being rubbed against the uneven pattern on the surface of the second substrate 11b.

At this time, the opening width of the recesses in the uneven pattern is set to a size that allows the second particles P2 to come into contact with the recesses, but not the support material S2. In other words, the opening diameter of the recesses in the uneven pattern on the second substrate 11b is preferably larger than the cumulative 50% particle size (median diameter) in the volume-based particle size distribution of the second particles P2. Furthermore, the opening diameter of the recesses is preferably smaller than the average size of the support material S2. Here, the opening diameter of the recesses in the uneven pattern is preferably the opening diameter in the short direction of the recesses, and more preferably the maximum opening diameter in the short direction of the recesses. This allows only the second particles P2 in the filler 241b to selectively come into contact with the recesses.

The second particles P2 that come into contact with the recesses are strongly restrained by the physical restraining force due to the structure of the concave-convex pattern, and by the electrostatic adhesion and adhesive force with the second substrate 11b and the structural material that constitutes the concave-convex pattern (here, the first particles P1), and are detached from the support material S2. Note that, for the sake of explanation, in Figure 8, the second particles P2 are supported on the surface of the support material S2, but it is also acceptable for there to be second particles P2 that are not supported on the support material S2 during the agitation, supply, or transport of the filler 241b.

Figure 9A is a schematic diagram showing the second substrate 11b after the first particles P1 have been transferred by the transfer unit 25a, and is a view of the second substrate 11b viewed from a direction perpendicular to the substrate surface. As shown in Figure 9A, a honeycomb pattern is formed on the second substrate 11b, in which the arrangement regions in which the first particles P1 are arranged in the shape of regular hexagons are aligned.

The first particles P1 are densely arranged within this regular hexagonal region, and the first particles P1 are not arranged in other areas (white areas in Figure 9A), leaving the adhesive portion of the surface of the second substrate 11b exposed. The regular hexagonal region in which the first particles P1 are held is referred to as the first pattern portion. Furthermore, the honeycomb pattern region in which the second particles P2 are held and which corresponds to the gaps in the first pattern portion is referred to as the second pattern portion.

Figure 9B is a schematic diagram of the second substrate 11b after the second particles P2 have been filled by the second filling device 24b, viewed from a direction perpendicular to the substrate surface. As shown in Figure 9B, the second particles P2 are densely arranged in the areas where the first particles P1 were not arranged and the adhesive portion was exposed. The first particles P1 and the second particles P2 are also densely arranged at the boundary between the areas where the first particles P1 are arranged and the areas where the second particles P2 are arranged. Note that particles can also be filled in the small gaps between the first particles P1 using a similar method. In this case, it is possible to fill the gaps between the first particles P1 using a filler containing particles with a particle size equivalent to that of the gaps between the first particles P1 using the same method as described above, thereby forming an even denser thin film.

The first particles P1 and the second particles P2 are placed using one filling device 24a and one filling device 24b, respectively, but multiple filling devices may be used. This can also improve compactness. Furthermore, the particles are not limited to the first particles P1 and the second particles P2; by adding a filling device, third particles other than the first particles and second particles can also be placed.

[Particle arrangement device 2]
10 is a diagram schematically illustrating the configuration of the particle arrangement device 2. The particle arrangement device 2 is a device that forms a particle layer 12 on a substrate 11, and includes a storage container 21 that stores and supplies the substrate 11, and a belt device 22 that transports the substrate 11. The particle arrangement device 2 may also include a liquid application device 201 that applies a liquid for providing adhesive portions on the substrate 11. In this case, in order to densely arrange the particles on the substrate 11, it is preferable to apply the liquid in a pattern on the substrate 11.

As the liquid applying device 201, a device that ejects liquid by an inkjet method or a device that applies liquid can be used, but a plate-based method such as a flexographic plate can also be used. Among these, it is preferable to use a device that ejects liquid by an inkjet method as the liquid applying device.
As a device for discharging liquid by an inkjet method, devices using various discharging methods, such as a thermal type, a piezo type, an electrostatic type, or a continuous type, can be used.

The liquid applied by the liquid application device 201 may be water-based or oil-based, as long as it contains a material to which the first particles P1 can adhere. The liquid may be selected as appropriate, such as by selecting a material that does not react with the first particles P1. The liquid application device 201 may also form the pattern L1 using multiple types of liquid. For example, the liquid application device 201 may apply two types of liquid that react with each other on the substrate 11 to increase adhesion. Examples of materials to which the first particles P1 can adhere include resins such as acrylic resins.

The powder application device 202 applies powder containing first particles P1 to the substrate 11 on which the liquid has been arranged in a pattern. As a result, the first particles P1 are fixed by the material on the substrate 11, and the particles P1 are fixed in a pattern corresponding to the pattern L1.

The powder application means used by the powder application device 202 can be a means for spraying or sprinkling the powder toward the substrate 11. The powder application device 202 may further include a means for removing the first particles P1 that are not fixed to the substrate 11 by means such as vibration, centrifugation, air blowing, or suction.

The particle placement device 2 may further include a drying device that evaporates at least a portion of the liquid applied by the liquid application device 201 to control the amount of material on the substrate 11 and the thickness of the pattern L1. This drying device may be located downstream of the liquid application device 201 and upstream of the powder application device 202. The material on the substrate after drying may be a liquid, a liquid containing solids, or solids only.

After the first particles P1 are fixedly positioned on the substrate 11, a liquid is applied by the liquid application device 203 to provide adhesive portions in at least the areas where the first particles P1 were not applied. The liquid application device 203 has the same function as the liquid application device 201. After the liquid is applied to the substrate 11 by the liquid application device 203, second particles P2 are applied by the second filling device 24. As a result, a dense particle layer 12 is formed on the substrate 11.

Furthermore, like the particle placement device 1, the particle placement device 2 may have a transfer unit. In this case, the transfer unit is provided downstream of the powder application device 202. The first particles P1 are transferred from the substrate 11 to another substrate having an adhesive portion. In the substrate to which the first particles P1 have been transferred, the second particles P2 can be placed using the second filling device 24 in areas where the first particles P1 are not placed and the adhesive portion is exposed. This makes it possible to precisely place the first particles P1 and the second particles P2 on the adhesive portion of the resin substrate.

In particle placement devices 1 and 2, the coverage of the resin substrate by the first particles P1 and second particles P2 is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more. The coverage of the resin substrate by the first particles P1 and second particles P2 can be measured by photographing the area where the particle layer is formed using an optical microscope from a direction perpendicular to the substrate, and calculating the area ratio of the first particles P1 and second particles P2 within that area using image processing software.

Using the particle placement device 1 or particle placement device 2 described above, first particles P1 are placed on the adhesive portion of the resin substrate in the first step (S101 in FIG. 1), and second particles P2 are placed.

(Second process)
The second step is a step of forming a laminate by stacking a plurality of resin substrates (hereinafter also referred to as substrates) on which particle layers are formed. The number of layers of the laminate is not particularly limited and is determined according to the desired electrode capacity. In addition, the laminate is preferably formed on a current collector such as a positive electrode current collector as a substrate. That is, the laminate preferably includes a substrate. As the current collector, known current collectors such as Al foil, SUS foil, platinum foil, and gold foil can be used. An electrolyte may also be used as the substrate.

In this case, the electrolyte may be a separately prepared solid electrolyte sheet or an electrolyte substrate consisting of only electrolyte particles on a similar substrate. A solid electrolyte may also be used as the electrolyte. When the electrode is a positive electrode, the solid electrolyte sheet or electrolyte substrate may have a negative electrode or a negative electrode substrate formed on the opposite side of the positive electrode substrate.

Figure 11 is a diagram showing a schematic configuration of the laminate forming device U3. The laminate forming device U3 has a conveying device 31 that conveys the substrate 11 on which the particle layer 12 has been formed, and a stage 32 that can be moved back and forth vertically by an actuator (not shown).

The conveying device 31 receives the substrate 11 having the particle layer 12 formed using the particle placement device, and conveys it to the stage 32. Examples of the conveying device 31 that can convey the substrate 11 include a belt conveyor, a roller, and a robot arm.
When the substrate 11 is transported to the stage 32 by the transport device 31, the stage 32 moves in the vertical direction by an amount equivalent to the thickness of the substrate 11 and the particle layer 12. By repeating the transport by the transport device 31 and the movement of the stage 32, multiple substrates 11, each having a particle layer 12 formed thereon, are stacked, and a laminate 15 is formed.

In this case, it is preferable that the back surface of the substrate 11 on which the particle layer 12 is formed has an adhesive portion. This adhesive portion allows the substrates to adhere to each other, increasing the strength of the laminate and preventing misalignment between the substrates even after the second process. Furthermore, by sandwiching the particle layer 12 between the substrates between the upper and lower adhesive portions, misalignment can be prevented during processing and storage of the laminate. The adhesive portion may be applied using a coating device (not shown) before lamination, or a pre-coated substrate may be used and the protective film coated on the coated surface may be peeled off before lamination.

It is preferable to have a static elimination step of eliminating static electricity from the substrate immediately before forming the laminate 15. The particle layer 12 and substrate 11 formed using the particle placement device are easily charged, and electrostatic repulsion occurs between the substrates during lamination. Therefore, when laminating in the second step, the substrates tend to peel off or gaps tend to form between the substrates. In the static elimination step, it is preferable to eliminate static electricity without contact using an electrostatic elimination blower or the like.
Furthermore, after the laminate 15 is formed, it is preferable to have a degassing step of degassing the laminate in order to reduce voids between the substrates. In the degassing step, degassing is preferably performed using a vacuum packaging machine or the like.

(3rd step)
The third step is a step of removing the resin substrate from the laminate to form a three-dimensional object containing active material particles and electrolyte particles. Preferably, the third step is a step of sintering the laminate to remove the resin substrate from the laminate. This allows the active material particles to have inner and outer surfaces. In other words, the third step can be said to be a step of forming inner surfaces on the active material particles, or a step of forming outer surfaces on the active material particles.
12 is a diagram showing a schematic configuration of the sintering apparatus U4. The sintering apparatus U4 has a conveying device 41 that conveys the laminate 15 and a heating furnace 42 that heats the laminate 15.

The conveying device 41 receives the laminate 15 from the laminate forming device and conveys it to the heating furnace 42. Similar to the conveying device 31, the conveying device 41 is preferably a device capable of conveying the laminate 15. Examples of devices capable of conveying the laminate 15 include a belt conveyor, rollers, and a robot arm.

The heating furnace 42 is a furnace that heats the laminate 15. The heating furnace 42 has a heating means 421, a pressurizing means 422, and an atmosphere adjusting means 423 (423a and 423b). A firing furnace used for firing ceramics or the like can be used as the heating furnace 42. The pressurizing means 422 pressurizes the laminate 15 being heated in the heating furnace 42, and pressurizes the laminate 15 before and after heating.

It is preferable that the pressurizing means 422 has a pressurizing portion that pressurizes the laminate 15 and is formed of a porous material that allows gas to easily pass through. The atmosphere adjusting means 423 has an atmosphere gas supplying means 423a and a pressure reducing means 423b, and adjusts the atmosphere gas in the processing space of the heating furnace 42.
As the atmospheric gas, an oxidizing atmosphere (O ₂ ), an inert atmosphere (Ar, N ₂ , etc.) or a reducing atmosphere (Ar—H ₂ ) can be used, but sintering may also be carried out in air.

When sintering the laminate, it is preferable to heat it at a temperature equal to or higher than the thermal decomposition temperature of the substrate 11 in the laminate 15, and it is preferable to heat it at a temperature lower than the thermal decomposition temperature of each particle layer in the laminate 15. The temperature to which the laminate is heated is preferably 200°C or higher and 1000°C or lower, more preferably 400°C or higher and 800°C or lower, particularly preferably 450°C or higher and 800°C or lower, and especially preferably 450°C or higher and 650°C or lower. It is preferable to maintain the sintering temperature for 30 minutes or more, more preferably 1 hour or higher. The upper limit is not particularly limited, but it may be, for example, 3 hours or less, or 2 hours or less. For example, it is preferable to maintain the sintering temperature for 30 minutes to 3 hours, or 1 hour to 2 hours.
The thermal decomposition temperature is the temperature at which the weight of a material begins to decrease when the temperature is gradually increased in a heating atmosphere in a sintering treatment device. Therefore, by heating the laminate at a temperature equal to or higher than the thermal decomposition temperature of the substrate 11, the substrate 11 in the laminate can be decomposed to reduce its weight, and the substrate 11 can be removed from the laminate.

The heating temperature is preferably equal to or higher than the thermal decomposition temperature of the substrate 11, but it is preferable to heat at a temperature even higher than the thermal decomposition temperature. Specifically, when the temperature is increased from room temperature (25°C) at a rate of 5°C/min in the atmosphere (typically air) used during heating in the sintering treatment device and thermogravimetric analysis is performed, it is preferable to heat at a temperature equal to or higher than the temperature at which the weight is reduced to 70% of its initial weight. Specifically, for example, 385°C or higher is preferable.

Furthermore, when similarly performing thermogravimetric analysis, it is more preferable to heat at a temperature equal to or higher than the temperature at which the weight is reduced to 50% of the initial weight, and even more preferable to heat at a temperature equal to or higher than the temperature at which the weight is reduced to 20% of the initial weight. Specifically, for example, a temperature of 400°C or higher is preferable, and 450°C or higher is even more preferable. This can shorten the time required to remove the substrate 11 and increase the removal rate of the substrate 11.

As such, when the sintering processing apparatus removes the substrate 11 by heating, it is preferable that the active material particles and solid electrolyte particles have a higher thermal decomposition temperature than the substrate 11. In general, inorganic materials tend to have higher thermal decomposition temperatures than organic materials, so it is preferable that the active material particles and solid electrolyte particles are inorganic materials and the substrate 11 is made of an organic material such as a resin. Furthermore, when the sintering processing apparatus removes the substrate 11 by heating, it is preferable that the active material particles be made of a material with a softening point temperature higher than the thermal decomposition temperature of the substrate 11.

The sintering treatment device preferably removes 90% by weight or more of the resin substrate in the laminate 15 by heating, more preferably removes 95% by weight or more, and even more preferably removes 97% by weight or more. At this time, the resin substrate is preferably burned or gasified and released to the outside as a gas. At this time, when the resin substrate gasified by pyrolysis is released to the outside of the laminate as a gas, it may push up the particle layer formed on the resin substrate and disrupt the shape.
For this reason, it is preferable to reduce the thickness of the resin substrate to reduce the influence on the particle layer.

Specifically, the thickness (μm) of the resin substrate is preferably 10 times or less, more preferably 5 times or less, and even more preferably 2 times or less, of the thickness of the particle layer on the resin substrate. Here, the thickness of the particle layer is defined as the thickness of the resin substrate surface in the direction (x, y) and the thickness of the layer in the direction (
z), the difference between the maximum and minimum values of z in the region (x, y, z) where each particle arranged on the resin substrate exists.

The thickness of the particle layer on the resin substrate is calculated by observing the cross section of the laminate 15 using a BIB-SEM, determining the particle presence area (x, z) using image processing software, where x is the resin substrate surface and z is the lamination direction of the resin substrate, and then calculating the difference between the maximum and minimum z values. The BIB-SEM imaging conditions, required image area, and image processing method are the same as those described below.

The thickness of the resin substrate, like the particle size of the active material particles, can be determined using a BIB-SEM, or it can be measured using a digital thickness gauge, etc. In addition, methods for identifying the active material particles, solid electrolyte particles, substrate, and adhesive portions during SEM observation using a BIB-SEM include elemental composition analysis using EDS.

To observe the cross section of the electrode, a cross section is processed using a broad ion beam (BIB) of Ar, and the cross section is then analyzed using a scanning electron microscope to obtain a two-dimensional image. Hereafter, this method of observing two-dimensional images is referred to as BIB-SEM. Details of the measurement method will be described later.

<BIB-SEM imaging method>
A cross-section of the electrode is photographed using a BIB-SEM.
The imaging conditions for the BIB-SEM are explained below.
If the battery contains electrodes, disassemble the battery and extract a sample containing the electrodes. For example, in the case of a laminated battery, open the laminate and extract the laminate containing the electrodes. To reduce the load of the cross-section processing described below, separate the other current collectors and electrodes that are not required for imaging from the laminate, and extract the sample containing the electrodes. The electrodes can be identified as the region between the electrolyte layer and the current collector layer.
The sample is cut using a wire saw (DWS3400/wire diameter 170 μm, diamond diameter 30 μm) to obtain a cut surface along the stacking direction. The cut surface is cross-sectionally processed using a broad ion beam of Ar (JEOL SM-09010 Cross Section Polisher). The cross-sectional processing conditions are a voltage of 6 kV and a current of 150 to 200 mA. A cross-section of the electrode sample in the stacking direction is obtained as a BIB-SEM image, and the cross-section is observed. Instead of a broad ion beam (BIB), a fine ion beam (FIB) can also be used, with the ion particle intensity and beam diameter changed in the beam.

The cross section is photographed using an electron microscope (ULTRA55) under the following conditions.
Detector: ESB (backscattered electron beam)
Observation conditions: accelerating voltage 3 kV
Magnification: 1000x Filter: ESB filter with 1500V bias applied

Next, elemental and compositional analysis of each particle of the electrode and the conductive resin was performed using SEM-EDX (XFlash Detector 630M manufactured by Bruker Corporation), and the active material particles, electrolyte particles, and conductive resin were identified.
The active material particles, electrolyte particles, and conductive resin are identified by the above-mentioned method. The electrode is analyzed by X-ray diffraction (XRD) or the like to identify the materials that make up the electrode. Then, the specific elements contained in each of the active material particles, electrolyte particles, and conductive resin are detected and identified by SEM-EDX using the above-mentioned method. In addition to the above-mentioned X-ray diffraction, the materials that make up the electrode can also be identified by electron energy loss spectroscopy (EELS) in a TEM. They can also be identified by Raman spectroscopy or Time of Flight-SIMS, and the materials that make up the electrode may be identified by combining the above-mentioned analytical methods.

The thickness of the resin substrate is preferably 1 μm or more and 1 mm or less. The thickness of the particle layer is preferably 0.1 μm or more and 100 μm or less.

Using a substrate made of an organic material such as resin as the substrate makes it easier to remove the substrate by heating. Materials that can be used to make the substrate include polyesters such as polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), and polyamides such as nylon. Of these, PET is preferred due to its low decomposition temperature and the low toxicity of the gases generated during thermal decomposition.

The sintering apparatus preferably exhausts the released gas to the outside of the heating furnace 42 using the pressure reducing means 423b. The resin base material can be burned and removed by creating an oxidizing atmosphere, i.e., an atmosphere containing oxygen gas such as air, inside the heating furnace 42 using the atmospheric gas supply means 423a or the like. However, depending on the active material particles and electrolyte particles used, sintering in an oxidizing atmosphere may cause decomposition or composition changes. In such cases, sintering in an inert atmosphere (Ar, _N2 , etc.) or a reducing atmosphere (Ar- _H2 ) is preferred.

As mentioned above, when the resin substrate is gasified by pyrolysis and released from the laminate 15 as a gas, the particle layers in the laminate 15 may be pushed up and their shape may change. Therefore, when heating in the heating furnace 42, the laminate 15 may be pressurized by the pressurizing means 422 before or during heating.

Figure 13A is a BIB-SEM image of the cross section of the laminate after the second step. It corresponds to the cross section of laminate 15, in which six lamination units, each including particle layer 12 and second substrate 11b, are laminated on resin substrate 14 so that particle layers 12 and second substrate 11b alternate. Figure 13B is a BIB-SEM image of three-dimensional object 16 after the third step. The resin substrate has been removed from laminate 15, leaving three-dimensional object 16 consisting of six particle layers. Figure 13C is an SEM image of the top of three-dimensional object 16. The first particles P1 and second particles P2 periodically arranged on second substrate 11b in the first step remain after the second step.

Fig. 14A is a BIB-SEM image of a three-dimensional object 16 according to one embodiment (Example 1) of the present disclosure, and Fig. 14B is an enlarged image of Fig. 14A.
A three-dimensional object 16 is formed by the manufacturing method of the present disclosure using positive electrode active material particles LiCoO ₂ (hereinafter referred to as LCO) as the first particles P1 and electrolyte particles Li ₃ BO ₃ (hereinafter referred to as LBO) as the second particles P2. In this embodiment, as shown in FIGS. 14A and 14B , the LCO particles (first particles P1) have a core portion P1a, a shell portion P1b, and radially protruding protrusions P1c on the surface of the shell portion. A gap portion P1d exists between the core portion and the shell portion. In FIG. 14B , P1d is an internal hole within the active material particle that communicates with the outer surface of the active material particle, and can also be referred to as a communicating hole 19-1. The LCO particles also have an inner surface 19 as shown by the solid line.

The presumed mechanism by which the three-dimensional object 16 has the above-described configuration in this embodiment will be described with reference to FIGS. 15 to 18-1 and 18-2A to 18-2D.
FIG. 15A shows an example of a temperature profile for each step (S101 to S104) of the manufacturing method of an electrode precursor according to the present disclosure, as well as a profile showing the redox behavior depending on the atmosphere. FIG. 15B is a schematic diagram showing the change in the LCO particles in the profile shown in FIG. 15A. In the first step (S101) and the second step (S102), the LCO particles on the resin substrate remain unchanged because they are produced at room temperature in an air atmosphere (or an inert atmosphere). Meanwhile, in the third step (S103), the resin substrate is heated by a sintering treatment device (in an air atmosphere). Here, when the temperature exceeds the melting point of the resin substrate and the substrate is sufficiently heated, the weight of the substrate begins to decrease.

16 shows the results of thermogravimetry (TG) of the resin substrate. The weight starts to decrease at around 300°C, which is above the melting point of the resin substrate (approximately 260°C).
Figure 17 shows the results of thermogravimetry-mass spectrometry (TG-MS). Figure 17A shows the measurement results for a mixed sample of LCO particles and a resin substrate. Figure 17B shows the measurement results for a sample consisting of only the resin substrate. Around 300°C, where the weight of the resin substrate begins to decrease, an increase in molecules with a molecular weight of 28, believed to be carbon monoxide (CO), a reducing gas, is observed. In Figure 17B, CO tends to increase up to around 500°C (solid line in Figure 17B), whereas in Figure 17A, CO tends to decrease just before 400°C (solid line in Figure 17A). Furthermore, around 500°C in Figure 17A, a decrease in molecules with a molecular weight of 32, believed to be oxygen, was observed (dashed line in Figure 17A), and an increase in molecules with a molecular weight of 44, believed to be carbon dioxide, was observed (dotted line in Figure 17A). The following is inferred from the results of TG and TG-MS.

As the temperature rises, the weight of the resin substrate begins to decrease (around 300°C), and CO, a reducing gas, is generated, increasing the reducibility. Some of the generated CO contributes to the reduction of the LCO particles. Therefore, the LCO particles are reduced and decomposed, and are thought to change into particles P1r that have some voids inside the LCO particles (Figure 15B).
On the other hand, the amount of CO generated decreases as the base material decreases, making it gradually more difficult for reductive decomposition to occur. As the weight of the base material decreases, the influence of CO decreases, and oxidation becomes dominant over reduction for the LCO particles. The reduced particles P1r are oxidized again to LiCoO ₂ , which is trivalent Co (around 500°C). At this time, it is thought that the LCO particles change into LCO particles having a core portion P1a, a shell portion P1b, and radially protruding protrusions P1c on the surface of the shell portion, while retaining the voids P1d generated during reductive decomposition inside the LCO particles.
18-2A to 18-2D show the results of STEM-EELS (Figs. 18-2A to 18-2D) at the respective regions shown in Figs. 18-2A to 18-2D in the LCO particle (Fig. 18-1) after the third step. It can be seen that the core region P1a (Area 4 in Fig. 18-2D), shell region P1b (Area 2 in Fig. 18-2B), and protrusion region P1c (Area 1 in Fig. 18-2A) in the LCO particle contain Co and are oxides with approximately the same composition.

(4th step)
The fourth step is a step of post-treating the three-dimensional object obtained in the third step. By performing the post-treatment, the electrode precursor can be easily filled with the filler material in the filling step (step 2-1) described below.
Examples of post-treatments include the pressurizing step described below, as well as physical and chemical treatments for improving wettability and filling properties, and known treatment methods can be used. Specifically, physical treatments include physical treatment of three-dimensional objects such as laser edging. Other examples include surface modification using UV irradiation or corona discharge, and chemical treatments such as gas adsorption. The pressurizing step will be described below as an example.

For example, the fourth step is a step of pressurizing the three-dimensional object 16 obtained in the third step from which the resin substrate has been removed (FIG. 12). The three-dimensional object 16 may be pressurized using a pressurizing means 422 during cooling or heat dissipation after heating. Alternatively, after the resin substrate has been removed using a sintering treatment device, the three-dimensional object 16 may be pressurized using a separate pressurizing device. While the pressurizing method is not particularly limited, it is preferable to use, for example, vacuum degassing, isostatic pressing, a general hydraulic press, or a roller press. Among these, a combination of vacuum degassing and isostatic pressing is preferred. It is also preferable to perform the fourth step by laminating the three-dimensional object with a release material such as nichrome foil, and it is even more preferable to further package the object in a laminate film.
The pressure applied during pressurization is preferably 5 to 500 MPa. Pressurization reduces the size of the pores (voids) within the three-dimensional object from which the resin substrate has been removed. Generally, as is known from capillary action, as the pore size decreases, liquids become more easily permeable. Therefore, post-treatment using pressurization further improves the filling ability of the filler material during the filling material filling process described below. Furthermore, post-treatment using pressurization can make it easier for the particles that make up the three-dimensional object to come into contact with each other. As a result, it is possible to increase the ionic conductivity and electronic conductivity, and to increase the strength of the three-dimensional object.
After the fourth step, another heat treatment may be performed to increase the density and strength of the three-dimensional object. In this case, the sintering treatment device of the third step may be used, or sintering may be performed separately using an electric furnace, a tubular furnace, a hot press, a hot isostatic pressing (HIP), or the like.

The electrode precursor obtained through the first to fourth steps contains active material particles and electrolyte particles and has voids. The voids refer to, for example, the gaps between the active material particles and the electrolyte particles. The presence of voids allows filling with a filler material, as described below. The proportion of voids in the electrode precursor may be 1 to 30% by volume, or may be 5 to 20% by volume.
If there are few voids, it is difficult for the filler material to be filled into the electrode precursor in the filling material filling process described below, making it difficult for the effects of the filler material to be realized. On the other hand, if there are many voids, contact between the active material particles and the electrolyte particles may be insufficient, resulting in reduced ionic and electronic conductivity within the electrode. The void ratio can be determined using a so-called 3D-SEM, in which continuous cross-sectional images are obtained by repeating cross-sectional processing (FIB) and SEM observation, and then reconstructed using analysis software to obtain a three-dimensional image. For a 50 μm x 50 μm region of the electrode portion, cross-sectional processing and SEM observation are repeated every 0.1 μm in the stacking direction to obtain a 50 μm x 50 μm x 10 μm three-dimensional image, and the void ratio is calculated. Alternatively, the void ratio may be determined from a BIB-SEM image of a two-dimensional positive electrode cross section. In this case, an SEM image of a 500 μm x 10 μm region including the center of the positive electrode cross section may be obtained, and the void ratio may be calculated. It can be calculated as the ratio of voids (pixels) to the entire image (pixels) using commercially available image analysis software (Photoshop (registered trademark)).

<Electrode manufacturing method>
An example of a method for manufacturing an electrode will be described in detail below with reference to the drawings. Hereinafter, the electrode can be made into a positive electrode by using a positive electrode precursor as the electrode precursor. Also, the electrode can be made into a negative electrode by using a negative electrode precursor as the electrode precursor.

The method for producing an electrode according to the present disclosure includes the following four steps (step 1-1, step 2-1, step 3-1, and step 4-1). It may also include step 5-1. The order of steps 1-1 and 2-1 is not particularly limited, and step 2-1 may be performed after step 1-1, or step 2-1 may be performed after step 1-1.
FIG. 19 is a conceptual diagram showing a method for manufacturing an electrode.
(1) Step 1-1 (not shown) of preparing an electrode precursor containing active material particles and having voids between the active material particles
(2) Step 2-1 (S201 in FIG. 19) of preparing a filler material to be filled into the electrode precursor; (3) Step 3-1 (S202 in FIG. 19) of filling the filler material from the outside to the inside of the electrode precursor;
(4) Step 4-1 (S203 in FIG. 19 ): Retaining the filling material filled in the electrode precursor inside the electrode precursor
(5) Step 5-1 (S204 in FIG. 19) of post-treating the electrode precursor obtained in Step 4-1

(Step 1-1)
Step 1-1 is a step of preparing an electrode precursor that contains active material particles and has voids between the active material particles. Step 1-1 is not particularly limited as long as it can prepare an electrode precursor, but the electrode precursor can be prepared using, for example, the above-mentioned method for producing an electrode precursor.
That is, step 1-1 preferably includes a first step of forming a particle layer containing active material particles and electrolyte particles on a resin substrate having an adhesive portion, a second step of forming a laminate by stacking a plurality of resin substrates on which the particle layer has been formed, a third step of removing the resin substrate from the laminate and forming a three-dimensional object containing the active material particles and the electrolyte particles, and a fourth step of post-treating the three-dimensional object.

(Step 2-1)
Step 2-1 is a step of preparing a filler material to be filled into the electrode precursor. Step 2-1 includes blending and preparing the following raw materials. As described above, the filler material needs to be a liquid in order to fill the voids in the electrode precursor. As the filler material, for example, a solution in which at least one selected from the group consisting of a conductive resin and a precursor of a conductive resin is dissolved in a solvent may be used, or a dispersion in which at least one selected from the group consisting of a conductive resin and a precursor of a conductive resin is dispersed in a dispersion medium may be used.
As the precursor of the conductive resin, for example, a monomer, oligomer, or polymer of a thermosetting resin or a photocurable resin can be used. That is, the conductive resin is preferably a cured product of a precursor of the conductive resin. Specific examples of the precursor of the conductive resin include ionic compounds having structures corresponding to the structures shown in the above formulas (1) to (6), the above polyols, and the above isocyanate compounds.

The filler material may be, for example, a mixture of the following raw materials:
At least one selected from the group consisting of a conductive resin and a precursor of a conductive resin; a supporting electrolyte such as a lithium salt, if necessary; a solvent or dispersion medium; and a conductive assistant, if necessary.

The solvent or dispersion medium is not particularly limited, and for example, an organic solvent can be used. Examples of organic solvents that can be used include alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone, acetone, and acetylacetone, and hydrocarbon solvents such as hexane and cyclohexane. Of these, methyl ethyl ketone is preferred.

The filler material may contain a supporting electrolyte. By including a supporting electrolyte in the filler material, the conductive resin in the electrode can contain the supporting electrolyte. Furthermore, the above-mentioned supporting electrolytes and conductive additives can be used.

(Step 3-1)
Step 3-1 is a step of filling the electrode precursor from the outside to the inside with the filler material prepared in Step 2-1. The filling means can be a known liquid filling means. The filling means preferably includes, for example, a coating step of applying the filler material to the electrode precursor and a penetration step of penetrating the applied filler material into the inside of the electrode precursor. It is more preferable to include a penetration step of penetrating the filler material into the inside of the electrode precursor so as to contact the inner surfaces of the active material particles, or a penetration step of penetrating the filler material into the inside of the electrode precursor so as to contact the outer surfaces of the active material particles. Examples of devices used in the coating step include an inkjet device, a dispenser device, a dip coater, a spin coater, a spray coater, and a roll coater. Of these, a dispenser device is preferably used. Examples of devices used in the penetration step include a vacuum dryer and a vacuum packaging machine. Pressure may be applied using a weight or the like to support penetration.

20A is a schematic diagram showing the filling process using a dispenser device 511. Filling material 50 is contained in a syringe in the dispenser device 511, and is applied to electrode precursor 18 through a nozzle at the tip of the syringe. Meanwhile, electrode precursor 18 formed on substrate 14 (electrode current collector or solid electrolyte sheet) is fixed to a support table 512.
Here, the filler material may be applied to a surface 18-1 (hereinafter also referred to as a particle arrangement surface) opposite to a contact surface 18-2 (hereinafter also referred to as a substrate support surface) of the electrode precursor 18 that contacts the substrate 14, or to an end portion 17 of the electrode precursor 18, but is preferably applied to the end portion 17. The reason for this will be described later. The end portion refers to the xz and yz surfaces when the substrate surface of the electrode precursor is the xy plane and the stacking direction is the z direction ( FIG. 13B ).
In the third step, the resin substrate is removed from the laminate to form a three-dimensional object, and therefore, in the electrode precursor 18, pores that communicate from the particle arrangement surface 18-1 are provided. In addition, pores that communicate from the end portion 17 are provided. This makes it easier for the filler material 50 to permeate evenly throughout the electrode precursor 18. As a result, the conductive resin is more likely to be positioned so as to contact the inner surfaces of the active material particles. In addition, the conductive resin is more likely to be positioned so as to contact the outer surfaces of the active material particles and connect the active material particles.
Furthermore, at the end portions, the interlayer spaces of the laminated structure of the electrode precursor are exposed, so when the filler material is applied to the end portions, the filler material is easily filled into the interior.
On the other hand, when the filler material 50 is applied from the particle arrangement surface 18-1 of the electrode precursor 18, that is, from the xy plane, it is preferable to apply the filler material 50 in small amounts to multiple locations on the xy plane in order to ensure uniform penetration.

Figure 20B is a schematic diagram showing the filling process using a dip coating device 513. The filling material 50 is contained in a dipping container 514. As the dip coating device 513 moves in the direction of the arrow, the filling material 50 is applied to the end of the electrode precursor 18.

Figure 20C is a schematic diagram showing the filling process using a spin coater 515. The filling material 50 is contained in a syringe in a dispenser device 511 and is applied onto the resin substrate 14 through the nozzle at the tip of the syringe. Meanwhile, the electrode precursor 18 formed on the resin substrate 14 (electrode current collector or solid electrolyte sheet) is fixed to the support table of the spin coater 515. The filling material 50 applied onto the resin substrate 14 is applied to the end of the electrode precursor 18 by the centrifugal force of the spin coater 515.

(Step 4-1)
Step 4-1 is a step of retaining the filler material filled into the electrode precursor in Step 3-1 inside the electrode precursor. The means for retaining the filler material is not particularly limited and is appropriately selected depending on the filler material. Examples include a step of thickening the filler material and a step of hardening the filler material. Specifically, when a thermosetting polymer electrolyte is used as the filler material, known means such as a vacuum oven can be used. When a UV-curable polymer electrolyte is used as the filler material, known means such as a UV irradiation device can be used.
When a UV irradiation device is used, depending on the thickness of the electrode, the filling material may not be easily cured by UV irradiation. In that case, the thickness of the electrode precursor is set to a thickness that allows the filled filling material to be easily cured, and multiple electrode precursors are molded on a substrate with high releasability, and after the filling material in each electrode precursor is cured, the electrodes can be obtained by transfer lamination.
Furthermore, the filling in step 3-1 may be carried out all at once, or may be carried out in small amounts in multiple separate steps. Specifically, when the filling is carried out in small amounts in multiple separate steps, the electrode may be obtained as follows. That is, after a small amount of filling in step 3-1 is carried out once, the filling material is held inside the electrode precursor in step 4-1. Thereafter, the filling in step 3-1 is carried out again, and the filling material is held inside the electrode precursor in step 4-1. In this way, the electrode precursor may be obtained by repeatedly carrying out steps 3-1 and 4-1.
The electrode precursor obtained in step 4-1 can be used as an electrode.
The electrode precursor obtained in the step 4-1 is preferably subjected to the step 5-1 to form an electrode.

(Step 5-1)
Step 5-1 is a step of post-treating the electrode precursor obtained in Step 4-1 to obtain an electrode. Examples of post-treatment include a pressurizing step of pressurizing the electrode precursor obtained in Step 4-1, a buffer layer forming step of forming an interfacial buffer layer with the electrolyte on the surface of the electrode, and a packaging step of covering with a protective film or vacuum-packaging with an AL laminate film or the like to prevent peeling, cracking, and exposure to the atmosphere during transportation and storage.
The pressurizing means used in the pressurizing step can be known means, and specific examples include vacuum degassing, isostatic pressing, a general hydraulic press, and a roller press. Among these, it is preferable to use a combination of vacuum degassing and isostatic pressing.
The means used in the buffer layer formation step can be known coating means, specifically vacuum deposition, ion plating, sputtering, chemical vapor deposition (CVD), and the various coating means of step 3-1. Instead of using the above-mentioned means, a separately prepared buffer layer sheet (such as a polymer electrolyte sheet) may be laminated. Alternatively, a buffer layer may be provided on the electrode by controlling the amount of filler material filled in step 3-1 in advance so that the filler material filled in step 3-1 also serves as a buffer layer.

<Secondary Battery Manufacturing Method>
A secondary battery can be manufactured using the above-described method for manufacturing an electrode. The method for manufacturing a secondary battery is not particularly limited, but the following specific examples can be given.
The following describes the case where the above-mentioned electrode manufacturing method is used as a manufacturing method for a positive electrode or a negative electrode. A positive electrode, a negative electrode, or both a positive electrode and a negative electrode can be manufactured by the above-mentioned electrode manufacturing method using a current collector or an electrolyte formed by a separate means as a base.

The secondary battery can be manufactured by laminating electrodes, current collectors, and electrolytes, optionally packaging the laminate with an aluminum laminate film or the like, and then molding and pressurizing the laminate. That is, the manufacturing method of the secondary battery may include the step of laminating electrodes, current collectors, and electrolytes. The electrodes can be any of the above-described electrodes.
Furthermore, a method for manufacturing a secondary battery may include the steps of preparing an electrode by the above-described electrode manufacturing method and providing a solid electrolyte adjacent to the electrode. Alternatively, the method may include the steps of simultaneously providing the above-described electrode and the solid electrolyte adjacent to the electrode. That is, the electrode and the solid electrolyte may be prepared separately in separate steps, or may be prepared together in the same step.

Here, the alternative means for forming the electrolyte is a known means, such as forming electrolyte particles into pellets using a uniaxial press or the like, and sintering the pellets in an electric furnace or the like.
The manufactured components are stacked in the order of a positive electrode current collector, a positive electrode, an electrolyte, a negative electrode, and a negative electrode current collector to manufacture a secondary battery. Examples of secondary batteries include laminated batteries packed in a laminate film and coin batteries packed in a coin case.
The particles constituting the positive electrode, electrolyte, and negative electrode may differ in the appropriate temperature and atmosphere during sintering. When handling such materials, it is preferable to separately manufacture the positive electrode, electrolyte, and negative electrode components and assemble them into a battery. Furthermore, when lithium metal or indium is used as the negative electrode, it is preferable to use the negative electrode as a metal foil or to form it into a current collector or electrolyte by a vacuum process such as sputtering. Because lithium metal has a strong reducing power, it is easily decomposed depending on the type of solid electrolyte. In this case, a buffer layer may be provided between the electrode and the electrolyte. It is preferable to use a polymer electrolyte or the like as the buffer layer.

In a specific example of the method for producing the secondary battery, the electrode is produced by forming a laminate of a positive electrode or a negative electrode on a current collector or an electrolyte as a base using the above-mentioned method for producing an electrode.
On the other hand, a laminate including two or more selected from the group consisting of a positive electrode current collector, a positive electrode, an electrolyte, a negative electrode, and a negative electrode current collector, which are the main components of a secondary battery, can be formed and manufactured as a three-dimensional object including an electrode.
For example, each substrate is prepared using the particle arrangement device 1. That is, a positive electrode current collector substrate, a positive electrode substrate, an electrolyte substrate, a negative electrode substrate, and a negative electrode current collector substrate. Each substrate may contain multiple types of particles (e.g., positive electrode active material particles and electrolyte particles in the case of a positive electrode substrate), or may contain only a single type of particle. When only a single type of particle is contained, a single type of dense particle layer can be formed on the substrate by using the same type of filler in the filling devices 24a and 24b.
The electrolyte base material is formed of a particle layer containing electrolyte particles. The negative electrode base material is formed of a particle layer containing negative electrode active material particles. The current collector base material is formed of a particle layer containing conductive particles. These base materials are stacked in the following order using a laminate molding device: positive electrode current collector base material, positive electrode base material, electrolyte base material, negative electrode base material, and negative electrode current collector base material, to produce a laminate. A three-dimensional object containing an electrode is formed using a sintering treatment device, thereby obtaining a secondary battery precursor containing an electrode precursor. A filling material is filled and retained in the electrode precursor (steps 2-1 to 4-1), allowing the secondary battery to be manufactured.
Furthermore, a bipolar secondary battery can be manufactured in the same manner, in which a positive electrode and a negative electrode are laminated on both sides of a current collector substrate. In this case, the filler material is filled and held in at least the electrodes, but it may also be filled and held in the electrolyte or current collector other than the electrodes.

<Electrode complex>
The electrode composite includes the electrode of the present disclosure and an electrolyte layer that transfers active material between the electrode and the electrode. By further providing an electrode that serves as a positive electrode or a negative electrode in the electrode composite, it is possible to provide a secondary battery that can mitigate expansion and contraction of the active material particles and suppress a decrease in battery output.

<Secondary battery>
The secondary battery includes a positive electrode according to the present disclosure and an electrolyte layer that transfers active material between the positive electrode and the electrolyte layer. The secondary battery also includes a negative electrode that transfers active material between the negative electrode and the electrolyte layer. This secondary battery can mitigate expansion and contraction of active material particles and suppress a decrease in battery output. Furthermore, by using a solid electrolyte such as an ion-conductive solid as the electrolyte layer, the secondary battery can be an all-solid-state battery.
The method for manufacturing the secondary battery is not particularly limited, but the above-mentioned manufacturing method can be used.

The present disclosure will be explained in more detail below using examples, but the present disclosure is not limited to these examples. In the following examples, parts are by weight unless otherwise specified.

Example 1
[Example of manufacturing a positive electrode]
<Example of manufacturing a positive electrode precursor>
The positive electrode precursor according to Example 1 was formed by the above-described method for producing an electrode precursor.
First, using the particle arrangement device 1 shown in FIG. 2, a particle layer consisting of positive electrode active material particles (first particles P1) and electrolyte particles (second particles P2) was formed on a resin substrate having an adhesive portion, thereby forming a resin substrate (first step).
The first particles P1 were LiCoO ₂ (hereinafter referred to as LCO), and the second particles P2 were Li ₃ BO ₃ (hereinafter referred to as LBO). The LCO used was manufactured by Nippon Chemical Industry Co., Ltd. (Cellseed C-5H), and the LBO used was manufactured by Toshima Manufacturing Co., Ltd.
The first substrate 11a was a PDMS (ultraviolet-curable liquid silicone rubber) sheet with a concave-convex structure on its surface. The second substrate 11b was a polyester (PET) resin sheet with adhesive portions coated with an acrylic adhesive on both sides. The thickness of the second substrate 11b (PET) used was 3 μm. The thickness of the adhesive portions was 1 μm. LCO particles were arranged in a honeycomb pattern on the resin sheet, and LBO particles were arranged in areas where no LCO particles were arranged ( FIG. 9B ).

The resin substrate on which the particle layer was formed obtained in the first step was used in the second step. That is, the resin substrate on which the particle layer was formed was laminated (three layers) on the current collector AC-1 (Al foil) using the laminate molding apparatus U3 shown in Fig. 11 to form a laminate.
Thereafter, the resin substrate was removed from the laminate by heating using a sintering treatment device U4 shown in Fig. 12 to form a three-dimensional object (third step). The sintering atmosphere was air, the sintering temperature was 510°C, and the sintering time was 1 hour.
The three-dimensional object was laminated with a release material (nichrome foil), packaged in a laminate film (Co-pack), and vacuum-packed using a vacuum packaging machine. The vacuum-packed laminate film was pressurized (196 MPa) using an isostatic pressure pressurizer for 1 minute to obtain a positive electrode precursor (step 4).

<Preparation example of filling material (step 2-1)>
(Production Example of Ionic Compound I-01)
A stirring bar and tetrahydrofuran (THF) were placed in a recovery flask equipped with a Dimroth condenser.
60 ml of sodium hydride (manufactured by Kanto Chemical Co., Ltd.) was added, and 24.0 g (0.60 mol) of sodium hydride (60% by mass, dispersed in liquid paraffin, manufactured by Tokyo Chemical Industry Co., Ltd.) was dispersed therein. The recovery flask was cooled in an ice bath. A solution of 10.2 g (0.15 mol) of imidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 60 ml of THF was slowly added dropwise, after which the ice bath was removed and the mixture was stirred at room temperature for 2 hours. 47.6 g (0.38 mol) of 2-bromoethanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was added at room temperature, and the mixture was heated to reflux at 70°C for 7 hours. After the reaction, the reaction solution was filtered, the insoluble matter was washed away with THF, and the solvent from the resulting filtrate was evaporated under reduced pressure. The obtained product was dissolved in 200 ml of dichloromethane, and an aqueous solution containing 43.6 g (0.15 mol) of bis(trifluoromethanesulfonyl)imide lithium (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved therein as an anion source was added, followed by stirring at room temperature for 10 hours. The obtained solution was separated to obtain an organic layer. This organic layer was washed three times with pure water. Next, dichloromethane was distilled off under reduced pressure to obtain ionic compound I-01. Ionic compound I-01 is a compound represented by the following formula:

(Example of manufacturing a precursor of a conductive resin)
Under a nitrogen atmosphere, 19.6 parts by mass of polymeric MDI (trade name: Millionate MR-200, manufactured by Tosoh Corporation) was used as an isocyanate in a reaction vessel, and 120.5 parts by mass of polyether polyol (trade name: Adeka Polyol PR-5007, manufactured by ADEKA Corporation) was gradually added dropwise while maintaining the temperature inside the reaction vessel at 65°C. After completion of the addition, the mixture was allowed to react at a temperature of 65°C for 3.5 hours. The resulting reaction mixture was cooled to room temperature, and 49.8 parts by mass of methyl ethyl ketone was added to obtain a solution of an isocyanate-terminated prepolymer having an isocyanate group content of 2.5% by mass.

The following materials were mixed with 100 parts by mass of the obtained solution of isocyanate group-terminated prepolymer and stirred to obtain a filling material.
Adeka Polyol PR-5007 113 parts by mass Ionic compound I-1 3.7 parts by mass Supporting electrolyte (lithium bis(trifluoromethanesulfonyl)imide (manufactured by Tokyo Chemical Industry Co., Ltd.)) 18.6 parts by mass Methyl ethyl ketone 175 parts by mass

Next, the positive electrode precursor obtained in step 4 was filled with the prepared filling material from a portion of the end face located on the periphery of the positive electrode precursor using the application device shown in FIG. 20A (step 3-1).
The positive electrode precursor filled with the filler material was heated in a vacuum oven (140°C) for 1 hour to harden the filler material into a conductive resin, and a positive electrode A-1 was formed (step 4-1). Samples with varying filling amounts of the filler material were prepared, and the level at which the conductive resin penetrated into the electrode without excess or deficiency was determined using the BIB-SEM described above.

A secondary battery was produced using the molded positive electrode A-1. The production method will be described. Other than the positive electrode A-1, the electrolyte layer SE-1 and the negative electrode C-1 were prepared by the following method. The electrolyte layer SE-1 was an electrolyte sheet (thickness 260 μm) obtained by pelletizing Li _1.5 Al _0.5 Ge _1.5 P ₃ O ₁₂ (hereinafter referred to as LAGP) powder (manufactured by Toshima Manufacturing Co., Ltd.) using a uniaxial press and sintering it in an electric furnace (850 ° C / 12 h). The negative electrode C-1 was made of indium foil (thickness 50 μm, manufactured by Nilaco).
A positive electrode current collector AC-1 (Al foil thickness 20 μm), a positive electrode A-1, an electrolyte layer SE-1, a negative electrode C-1, and a negative electrode current collector CC-1 (Cu foil thickness 20 μm) were laminated in this order, and a tab lead for an extraction electrode previously welded to the current collector was packaged in an aluminum laminate film so as to be positioned outside the laminate. Thereafter, the laminate was formed into a laminate cell shape using a vacuum packaging machine, and pressurized (196 MPa) for 1 minute using an isostatic pressure pressurizer to produce secondary battery SB-1.

22A to 22D are electron microscope images of the cross section of positive electrode A-1 taken using the method described below. FIG. 22A is an electron microscope image. FIG. 22B identifies LCO particles (P1t, P1u, P1v, P1w, P1x, P1y, P1z) based on an EDX image (element Co), with particle boundaries indicated by dashed lines. The LCO particles have a core portion P1a, a shell portion P1b, and radially protruding protrusions P1c on the surface of the shell portion. Furthermore, gaps P1d exist between the core portion and the shell portion (FIG. 14). In FIG. 22B, the boundaries of the gaps P1d within particles P1t and P1u are indicated by solid lines. In other words, the solid lines can be said to represent the inner surfaces of the active material particles.
Figure 22C is an EDX image of sulfur element derived from the conductive resin. As in Figure 22B, particle boundaries are indicated by dashed lines. The conductive resin is present so as to contact the inner surfaces of the gaps P1d, i.e., the inner surfaces of the active material particles. Furthermore, the conductive resin is arranged so as to contact the outer surfaces of the LCO particles and connect the LCO particles.
Figure 22D is an EDX image of boron element derived from the solid electrolyte LBO. As in Figure 22B, particle boundaries are indicated by dashed lines. As can be seen from Figures 22C and 22D, conductive resin and inorganic electrolyte are unevenly distributed between the LCO particles.

FIG. 23 is a low-magnification electron microscope image of the cross section of positive electrode A-1. FIG. 23A is an electron microscope image. FIG. 23B identifies LCO particles based on an EDX image (element Co), with the particle boundaries indicated by dashed lines. FIG. 23C is an EDX image (element Co), FIG. 23D is an EDX image (element C), and FIG. 23E is an EDX image (element B). In FIGS. 23C to 23E, the boundaries of the LCO particles are indicated by dashed lines. A conductive resin is present so as to contact the inner surfaces of the gaps P1d, i.e., the inner surfaces of the active material particles. Furthermore, the conductive resin is arranged so as to contact the outer surfaces of the LCO particles and connect the LCO particles. Furthermore, the conductive resin is
It exists so as to overlap with the region containing BO.

24A to 24C are schematic diagrams illustrating features of the present disclosure, for example, according to Example 1. Fig. 24A is a schematic diagram of an electrode, Fig. 24B shows the element distribution of EDX along line A-A' in Fig. 24A, and Fig. 24C shows the element distribution of EDX along line B-B' in Fig. 24A.
24A to 24C, the conductive resin is disposed in contact with the outer surfaces of the active material particles and connects the active material particles together, forming a good interface with the active material particles as well as with the supporting electrolyte particles, which is thought to improve ion diffusion within the electrode.
It is also believed that the conductive resin changes shape in response to the expansion and contraction of the active material particles during charging and discharging, thereby suppressing the decline in ionic and electronic conductivity. Furthermore, it is believed that the voids within the electrode function as spaces for deformation, including expansion and contraction of the conductive resin in response to the expansion and contraction of the active material particles.

The conductive resin also fills the gaps P1d within the LCO particles. That is, it is positioned so that it contacts the inner surface of the LCO particles. In this way, the conductive resin forms a favorable interface with the LCO particle surface having the protrusions P1c, and also with the gaps P1d within the LCO particles, which is thought to further improve ion diffusion within the electrode. Furthermore, by filling the LCO particles with flexible conductive resin, the shape changes in response to the expansion and contraction of the active material particles during charging and discharging. This is thought to prevent a decrease in ionic and electronic conductivity within the particles. Furthermore, the conductive resin in contact with the inner and outer surfaces of the active material particles is thought to deform in response to the expansion and contraction of the active material particles during charging and discharging, so as to connect discontinuities within the active material particles (e.g., cracks and gaps) and discontinuities between particles (e.g., voids), thereby maintaining ionic conductivity.

<Cross-section observation of positive electrode>
To observe the cross section of the positive electrode, the battery was disassembled in the stacking direction and the positive electrode was removed. The removed positive electrode was cut with a wire saw (DWS3400/wire diameter 170 μm, diamond diameter 30 μm). The cut surface was cross-sectioned with a broad ion beam of Ar (JEOL SM-09010 Cross Section Polisher). The cross-section processing conditions were a voltage of 6 kV and a current of 150 to 200 mA.
The cross section was photographed using an electron microscope (ULTRA55) to obtain a BIB-SEM image. The conditions were as follows:
Detector: ESB (backscattered electron beam)
Observation conditions: accelerating voltage 3 kV
Magnification: 1000x Filter: ESB filter with 1500V bias applied

Next, elemental mapping was performed using SEM-EDX (Bruker XFlash Detector 630M). From the elemental mapping results, active material particles, electrolyte particles, and conductive resin were identified.

The evaluation method for the secondary battery will be described below.
<Charge/discharge characteristics capacity retention rate>
The active material particle mass of the positive electrode (M × number of layers × positive electrode area ^cm ) was calculated from the active material particle mass M (g/cm ) per unit area of the resin substrate ^on which the particle layer was formed. The active material particle mass M per unit area was determined as follows.
The weight of the first substrate 11a was measured after the first particles P1 were filled by the first filling device 24a in the particle arrangement device 1. Next, the weight of the first substrate 11a was measured after the above-mentioned first particles P1 were transferred to the second substrate 11b. The difference was calculated to determine the mass of the first particles P1 on the second substrate 11b. Then, the mass of the first particles P1 was divided by the area of the second substrate 11b (the area of the uneven region) to calculate the active material particle mass M per unit area.

Another calculation method is to use ICP atomic emission spectroscopy. Three levels of resin substrates on which particle layers are formed, the active material particle mass per unit area M (g/cm ² ) of which has been previously determined by the method described above, are prepared. These resin substrates are dissolved by microwave acid decomposition (ETHOS PRO), and the acid decomposition solution is diluted with ultrapure water. ICP-AES measurement (CIROS CCD) is then performed to quantify the Co element. A calibration curve of the active material particle mass per unit area M (g/cm ² ) versus the obtained element concentration is obtained. From the calibration curve, the active material particle mass per unit area M (g/cm ² ) of the resin substrate on which the particle layer to be measured is formed can be determined.

The current value at a current rate of 0.4 C was determined, and charge/discharge measurements (constant current charge/constant current discharge) were performed at a current rate of 0.4 C. The measurements were performed using a charge/discharge device (manufactured by Biologic). Figure 21 shows the measured charge/discharge curves. The vertical axis represents the battery cell voltage (V vs. Li/Li ⁺ ), and the horizontal axis represents the battery cell capacity (mAh/g). The capacity is the capacity per mass of the active material in the positive electrode.
The actual capacity of the LCO was 120 mAh/g, and the cutoff voltage (vs. Li) was 4.2 V (charge)/2.6 V (discharge). The capacity retention rate was the ratio of the discharge capacity to the charge capacity (discharge capacity/charge capacity × 100%). The above measurement was repeated five times, and the average value was calculated. A value of 80% or more was considered good.

<Cycle characteristics>
A cycle evaluation (repeated charge/discharge measurement in a constant current mode) was performed at a current rate of 0.4 C. The charge/discharge measurement was repeated until the capacity retention rate described above reached 80% or less, and the number of times n was calculated. A value of 10 or more was considered good.
As a result of the battery evaluation, the capacity retention rate was 100% and the number of cycles n was 12. If the charge/discharge characteristics and cycle characteristics were good according to the above evaluation, the battery was evaluated as A (Table 1).

Example 2
A positive electrode A-2 was produced in the same manner as in Example 1, except that the filler material was applied to the particle arrangement surface of the positive electrode precursor and then filled into the positive electrode precursor. A secondary battery SB-2 was produced in the same manner as in Example 1, except that positive electrode A-2 was used.
When a cross section of positive electrode A-2 was observed, it was found that, similar to positive electrode A-1, the conductive resin was located so as to contact the inner surface of the gap. Furthermore, similar to positive electrode A-1, the conductive resin was located so as to contact the outer surfaces of the LCO particles and connect the LCO particles. Furthermore, similar to positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles.
Furthermore, it was confirmed that the obtained secondary battery SB-2 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

Example 3
A positive electrode A-3 was produced in the same manner as in Example 1, except that the sintering temperature in the third step was changed from 510° C. to 700° C. A secondary battery SB-3 was produced in the same manner as in Example 1, except that the positive electrode A-3 was used.
25A to 25C are electron microscope images of the cross section of positive electrode A-3. Fig. 25A is an electron microscope image, Fig. 25B is an EDX image (element C), and Fig. 25C is an EDX image (element B). Perhaps due to the high temperature firing, oxidation of the LCO particles progressed, returning them to a form similar to that of the raw material LCO particles, and no gaps were observed.
In the cross-sectional structure of the obtained positive electrode A-3, the conductive resin was in contact with the outer surfaces of the LCO particles and was arranged to connect the LCO particles. Furthermore, similar to positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles.
Furthermore, it was confirmed that the obtained secondary battery SB-3 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

Example 4
A positive electrode A-4 was produced in the same manner as in Example 1, except that the first particles were changed to LCO (CellSeed C-8H) having a large particle size. When a cross-sectional observation of the positive electrode A-4 was performed, it was found that, similar to the positive electrode A-1, the conductive resin was located so as to contact the inner surface of the gap. Furthermore, similar to the positive electrode A-1, the conductive resin was located so as to contact the outer surface of the LCO particles and connect the LCO particles. Furthermore, similar to the positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles. Furthermore, it was confirmed that the resulting secondary battery SB-4 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

Example 5
A positive electrode A-5 was produced in the same manner as in Example 1, except that pressure (50 MPa) was applied by the pressure means 422 in the sintering treatment apparatus U4. When a cross-section of the positive electrode A-5 was observed, it was found that, similar to the positive electrode A-1, the conductive resin was located so as to contact the inner surface of the gap. Also, similar to the positive electrode A-1, the conductive resin was located so as to contact the outer surface of the LCO particles and connect the LCO particles. Furthermore, similar to the positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles. Furthermore, it was confirmed that the resulting secondary battery SB-5 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

Example 6
A positive electrode A-6 was produced in the same manner as in Example 1 _, except that _{Li5.9Yb0.81La0.09Zr0.1} ( _BO3 ) ₃ (LYbBO-1 ₎ was used as _the electrolyte particles. A secondary battery SB-6 was produced in the same manner as in Example 1, except that the positive electrode A-6 was used.
When a cross section of positive electrode A-6 was observed, it was found that, similar to positive electrode A-1, the conductive resin was located so as to contact the inner surface of the gap. Furthermore, similar to positive electrode A-1, the conductive resin was located so as to contact the outer surface of the LCO particles and connect the LCO particles. Furthermore, similar to positive electrode A-1, the conductive resin was present so as to overlap the region containing LBO. Furthermore, the conductive resin and the inorganic electrolyte were unevenly distributed between the LCO particles.
Furthermore, it was confirmed that the obtained secondary battery SB-6 had good capacity retention and cycle characteristics, similar to the secondary battery SB-1.

Table 1 shows a comparison table summarizing the formulations and production conditions of Examples 1 to 6 and the evaluation results.

In the table, the application location indicates the location where the filler material was applied to the positive electrode precursor in step 3-1, the contact location indicates the contact location between the conductive resin and the LCO particles, and the presence or absence of co-distribution indicates whether the conductive resin and the inorganic electrolyte are co-distributed unevenly.

The present disclosure relates to the following configurations and methods.
[Configuration 1]
An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
The conductive resin is positioned so as to contact the inner surface.
[Configuration 2]
The electrode according to Aspect 1, wherein the conductive resin includes an ionic conductive resin.
3. The electrode according to claim 1, wherein the conductive resin comprises a resin containing an ionic functional group and a supporting electrolyte.
[Configuration 4]
4. The electrode according to any one of Aspects 1 to 3, wherein the conductive resin comprises a urethane resin containing an ionic functional group and a supporting electrolyte.
[Configuration 5]
5. The electrode according to any one of Aspects 1 to 4, wherein the inner surface is continuous with the outer surface of the active material particles.
[Configuration 6]
6. The electrode of claim 5, wherein the conductive resin is in contact with the outer surface.
[Configuration 7]
7. The electrode according to any one of Aspects 1 to 6, wherein at least one selected from the group consisting of a conductive resin, a conductive assistant, and a supporting electrolyte is contained between the active material particles.
[Configuration 8]
A supporting electrolyte is contained between the active material particles,
8. The electrode of any one of embodiments 1 to 7, wherein the supporting electrolyte comprises an inorganic electrolyte.
[Configuration 9]
9. The electrode of claim 8, wherein, between the particles, a region containing the conductive resin overlaps a region containing the inorganic electrolyte.
[Configuration 10]
10. The electrode of any one of Aspects 1 to 9, wherein the active material particles include lithium cobalt oxide.
[Configuration 11]
11. The electrode according to any one of Aspects 5 to 10, wherein the active material particles have protrusions protruding from the outer surface.
[Configuration 12]
12. The electrode according to any one of configurations 1 to 11, wherein the conductive resin contains at least one of polyurethane, polyacrylic, and polyether in its main chain structure.
[Configuration 13]
The electrode according to any one of configurations 1 to 12, wherein the conductive resin contains, in its main chain structure, a polyether that is a copolymer of polyethylene glycol and polypropylene glycol. [Configuration 14]
14. The electrode according to any one of configurations 1 to 13, wherein the conductive resin has higher flexibility than the active material particles.
[Configuration 15]
An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an outer surface;
The resin is disposed in contact with the outer surface and connects the active material particles.
[Configuration 16]
16. The electrode of claim 15, wherein the conductive resin comprises an ionic conductive resin.
[Configuration 17]
17. The electrode according to claim 15 or 16, wherein the conductive resin contains at least one of polyurethane, polyacrylic, and polyether in its main chain structure.
[Configuration 18]
18. The electrode according to any one of embodiments 15 to 17, wherein the conductive resin contains polyether, which is a copolymer of polyethylene glycol and polypropylene glycol, in its main chain structure.
[Configuration 19]
the active material particles have an inner surface;
19. The electrode of any of aspects 15-18, wherein the inner surface is continuous with the outer surface.
[Configuration 20]
20. The electrode of claim 19, wherein the conductive resin is positioned so as to contact the inner surface.
[Configuration 21]
A supporting electrolyte is contained between the active material particles,
21. The electrode of any one of embodiments 15 to 20, wherein the supporting electrolyte comprises an inorganic electrolyte.
[Configuration 22]
22. The electrode of claim 21, wherein a region between the particles containing the conductive resin overlaps a region between the particles containing the inorganic electrolyte.
[Configuration 23]
An electrode composite including an electrode and an electrolyte layer that transfers an active material between the electrode and the electrolyte layer,
23. An electrode composite, wherein the electrode is the electrode according to any one of configurations 1 to 22.
[Configuration 24]
A secondary battery including a positive electrode and an electrolyte layer that transfers an active material between the positive electrode and the electrolyte layer,
the positive electrode is the electrode of any one of configurations 1 to 22;
The secondary battery includes a negative electrode that transfers the active material between the negative electrode and the electrolyte layer.
[Method 25]
a 1-1 step of preparing an electrode precursor including active material particles and having gaps between the active material particles;
a 2-1 step of preparing a filling material to be filled into the electrode precursor;
a 3-1 step of filling the filling material from the outside to the inside of the electrode precursor;
and a 4-1 step of retaining the filler material filled inside the electrode precursor inside the electrode precursor.
[Method 26]
26. The method for producing an electrode according to Method 25, wherein the step 3-1 includes a penetration step of penetrating the filler material into the interior of the electrode precursor so as to be in contact with the outer surfaces of the active material particles.
[Method 27]
The method for producing an electrode according to Method 25 or 26, wherein Step 1-1 includes a step of forming an inner surface on the active material particles.
[Method 28]
28. The method of claim 27, wherein forming the inner surface on the active material particles comprises sintering the active material particles.
[Method 29]
The step 1-1 is
a first step of forming a particle layer containing active material particles and electrolyte particles on a resin substrate having an adhesive portion;
a second step of forming a laminate by laminating a plurality of resin substrates on which the particle layer is formed;
a third step of removing the resin substrate from the laminate to form a three-dimensional object containing active material particles and electrolyte particles;
A fourth step of post-processing the three-dimensional object;
29. A method for producing an electrode according to any one of methods 25 to 28, comprising:
[Method 30]
30. The method for producing an electrode according to any one of Methods 25 to 29, wherein Step 3-1 includes a penetration step of penetrating the filler material into the electrode precursor so as to contact the inner surfaces of the active material particles.
[Method 31]
the electrode precursor has an end portion;
31. The method for producing an electrode according to any one of Methods 25 to 30, wherein Step 3-1 includes applying the filler material to the end of the electrode precursor.

Claims (20)

An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
the conductive resin is positioned so as to be in contact with the inner surface,
The conductive resin is an electrode containing a resin having an ionic functional group and a supporting electrolyte . An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
the conductive resin is positioned so as to be in contact with the inner surface,
The conductive resin is an electrode containing a urethane resin containing an ionic functional group and a supporting electrolyte. An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
the conductive resin is positioned so as to be in contact with the inner surface,
The electrode contains a supporting electrolyte between the active material particles, the supporting electrolyte containing an inorganic electrolyte . An electrode applied to a secondary battery,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
the conductive resin is positioned so as to be in contact with the inner surface,
the inner surface is continuous with the outer surface of the active material particle,
The active material particles have protrusions protruding from the outer surface of the electrode. The electrode according to claim 4 , wherein the conductive resin includes an ionic conductive resin. 5. The electrode according to claim 4 , wherein the conductive resin comprises a resin containing an ionic functional group and a supporting electrolyte. 5. The electrode according to claim 4 , wherein the conductive resin contains a urethane resin containing an ionic functional group and a supporting electrolyte. The electrode described in claim 1, wherein the inner surface is continuous with the outer surface of the active material particles. The electrode according to claim 8 , wherein the conductive resin is in contact with the outer surface. The electrode described in claim 1, wherein at least one selected from the group consisting of a conductive resin, a conductive additive, and a supporting electrolyte is contained between the active material particles. A supporting electrolyte is contained between the active material particles,
10. The electrode of claim 1, wherein the supporting electrolyte comprises an inorganic electrolyte. The electrode according to claim 3 , wherein, between the particles, a region containing the conductive resin overlaps a region containing the inorganic electrolyte. The electrode described in claim 1, wherein the active material particles include lithium cobalt oxide. The electrode according to claim 8 , wherein the active material particles have protrusions protruding from the outer surface. The electrode described in claim 1, wherein the conductive resin contains at least one of polyurethane, polyacrylic, and polyether in its main chain structure. The electrode described in claim 1, wherein the conductive resin contains a polyether, which is a copolymer of polyethylene glycol and polypropylene glycol, in its main chain structure. The electrode described in claim 1, wherein the conductive resin has higher flexibility than the active material particles. An electrode composite including an electrode and an electrolyte layer that transfers an active material between the electrode and the electrolyte layer,
the electrode includes active material particles and a conductive resin,
the active material particles have an inner surface;
The conductive resin is positioned so as to be in contact with the inner surface. An electrode composite including an electrode and an electrolyte layer that transfers an active material between the electrode and the electrolyte layer,
An electrode composite, wherein the electrode is the electrode according to any one of claims 1 to 17 . A secondary battery including a positive electrode and an electrolyte layer that transfers an active material between the positive electrode and the electrolyte layer,
The positive electrode is the electrode according to any one of claims 1 to 17 ,
The secondary battery includes a negative electrode that transfers the active material between the negative electrode and the electrolyte layer.