JP7819081B2 - Manufacturing method for all-solid-state batteries - Google Patents

Description

This disclosure relates to a method for manufacturing an all-solid-state battery.

Currently, all-solid-state batteries, which offer high safety and energy density, are attracting attention. All-solid-state batteries contain a laminated body, including a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, as their power-generating element. Various proposals have been made regarding the structure and manufacturing methods of all-solid-state batteries.

Claim 1 of Patent Document 1 (JP 2019-207840 A) describes "an all-solid-state battery including a laminated electrode body having a structural portion in which an electrode mixture layer and a solid electrolyte layer are laminated, and a sealing portion covering at least a laminate end face of the laminated electrode body, wherein the electrode mixture layer contains an active material and a binder resin, the sealing portion contains a sealing resin and insulating particles, and the absolute value of the difference between the solubility parameter of the binder resin contained in the electrode mixture layer and the solubility parameter of the sealing resin contained in the sealing portion is 1.9 (cal/cm ³ ) ^0.5 or less."

Patent Document 2 (Japanese Patent No. 6673249) describes, in claim 1, "a method for manufacturing a laminated all-solid-state battery, the method including: enclosing, in an exterior body made of a laminate film, an all-solid-state battery stack having one or more all-solid-state battery elements, each having an anode current collector layer having an anode current collector tab, an anode active material layer, a solid electrolyte layer, a cathode active material layer, and a cathode current collector layer having a cathode current collector tab stacked in this order; applying pressure to the all-solid-state battery stack encased in the exterior body in the stacking direction from outside the exterior body; injecting a filler material into the exterior body while maintaining the pressure; and sealing the exterior body, wherein the pressure applied in the step of applying pressure to the all-solid-state battery stack in the stacking direction is greater than the filler material injection pressure in the step of injecting the filler material."

Patent Document 3 (Japanese Patent No. 6772855) describes, in claim 1, "an all-solid-state battery comprising: an all-solid-state battery element having one or more unit cells each having an anode current collector layer, an anode active material layer, a solid electrolyte layer, a cathode active material layer, and a cathode current collector layer arranged in this order; a metal exterior body having an opening at at least one end and housing the all-solid-state battery element; a resin sealant sealing the opening and in contact with the surface of the all-solid-state battery element facing the opening; and an anode current collector layer protruding portion and a cathode current collector layer protruding portion protruding from the resin sealant toward the side opposite the all-solid-state battery element, wherein the resin sealant fills at least a portion of the gap between the outer periphery of the all-solid-state battery element and the inner periphery of the metal exterior body to form a gap filler, and the resin sealant is a curable resin."

Japanese Patent Application Laid-Open No. 2019-207840 Patent No. 6673249 Patent No. 6772855

When conventional all-solid-state batteries are used under reduced pressure, if the pressure inside the case becomes higher than the external pressure, the battery expands, resulting in a decrease in battery performance. Even when the pressure inside the case is negative, to prevent the battery from expanding under reduced pressure, it is necessary to create a high vacuum inside the case or use a pressurized case structure. In light of this situation, one of the objectives of the present disclosure is to provide a manufacturing method that can easily produce all-solid-state batteries that are less likely to expand even under reduced pressure.

One aspect of the present disclosure relates to a first manufacturing method for an all-solid-state battery. The first manufacturing method is a manufacturing method for an all-solid-state battery including at least one unit cell including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and includes the steps of: (i) disposing a first resin-containing material that has not yet been cured and has fluidity within an exterior body having an opening; and (ii) inserting a stack including the at least one unit cell into the exterior body, allowing the first resin-containing material to complete curing, and disposing the cured first resin-containing material between the exterior body and the stack.

One aspect of the present disclosure relates to a second manufacturing method for an all-solid-state battery. The second manufacturing method is a manufacturing method for an all-solid-state battery including at least one unit cell including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and includes the steps of: (I) disposing a stack including the at least one unit cell within an exterior body having an opening; and (II) supplying a fluid resin-containing material that has not yet cured, starting from the lower side of the exterior body, filling the exterior body with the resin-containing material, and then completing the curing of the resin-containing material, thereby disposing the cured resin-containing material between the exterior body and the stack.

The manufacturing method disclosed herein makes it easy to manufacture all-solid-state batteries that are less likely to expand even under reduced pressure.

FIG. 1A is a top view schematically illustrating an example of a laminate used in the first embodiment. FIG. 1B is a cross-sectional view taken along line IB-IB in FIG. 1A. FIG. 2A is a cross-sectional view schematically showing one step of the manufacturing method of the first embodiment. FIG. 2B is a cross-sectional view schematically showing a step subsequent to the step shown in FIG. 2A. FIG. 3A is a cross-sectional view schematically illustrating an example of an exterior body used in the manufacturing method of embodiment 1. FIG. 3B is a cross-sectional view schematically illustrating another example of an exterior body used in the manufacturing method of embodiment 1. FIG. 3C is a cross-sectional view schematically illustrating an example of deformation of the exterior body in the manufacturing method of embodiment 1. FIG. 4A is a cross-sectional view schematically showing one step of the manufacturing method of the second embodiment. FIG. 4B is a cross-sectional view schematically showing a step subsequent to the step shown in FIG. 4A. FIG. 5 is a cross-sectional view schematically illustrating an example of one step of the manufacturing method according to the second embodiment. FIG. 6 is a cross-sectional view schematically illustrating another example of a step of the manufacturing method according to the second embodiment.

The following describes examples of embodiments of the present disclosure, but the present disclosure is not limited to the examples described below. Specific numerical values and materials may be used as examples in the following description, but other numerical values and materials may be used as long as the invention of the present disclosure can be implemented. In this specification, the expression "numerical value A to numerical value B" includes numerical value A and numerical value B and can be read as "greater than or equal to numerical value A and less than or equal to numerical value B." In the following description, when numerical lower and upper limits for specific physical properties or conditions are given as examples, any of the exemplified lower limits can be combined with any of the exemplified upper limits, as long as the lower limit is not greater than or equal to the upper limit.

The first and second manufacturing methods for an all-solid-state battery are described below. The first and second manufacturing methods may be referred to as "manufacturing method (M1)" and "manufacturing method (M2)" below.

Manufacturing method (M1) and manufacturing method (M2) are each methods for manufacturing an all-solid-state battery including at least one unit cell that includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. Manufacturing method (M1) and manufacturing method (M2) use a laminate that includes at least one unit cell. This laminate may be referred to below as a "laminate (S)." Typically, a positive electrode lead tab and a negative electrode lead tab protrude from the laminate (S). Examples of the configuration of all-solid-state batteries will be described later. There are no limitations on the method for preparing the laminate (S). The laminate (S) may be formed by the method described below, or a formed laminate (S) may be obtained and used.

(First manufacturing method (manufacturing method (M1)))
In a conventional manufacturing method, the laminate (S) is placed inside an exterior body, and then a sealing resin is injected through an opening in the exterior body to surround the laminate (S). However, because the viscosity of the sealing resin is relatively high, it is difficult to inject the sealing resin without forming a gap between the laminate (S) and the exterior body. If a large gap where no sealing resin is placed is formed between the laminate (S) and the exterior body, the battery is likely to expand under reduced pressure.

As described below, in manufacturing method (M1), the first resin-containing material is disposed inside the exterior body beforehand, and then the laminate (S) is inserted into the exterior body. Therefore, manufacturing method (M1) can prevent the formation of large voids between the laminate (S) and the exterior body where no sealing resin is disposed. As a result, an all-solid-state battery that is less likely to expand even under reduced pressure is obtained. Furthermore, since manufacturing method (M1) makes it easy to dispose the first resin-containing material in the exterior body, all-solid-state batteries can be easily manufactured.

The first manufacturing method (manufacturing method (M1)) for an all-solid-state battery includes steps (i) and (ii) in this order. These steps are described below.

(Step (i))
Step (i) is a step of placing a first resin-containing material that has fluidity and has not yet completely cured within an exterior body having an opening. The exterior body having an opening can be, for example, a rectangular cylindrical exterior body with a bottom. The rectangular cylindrical portion has two main walls (plate-shaped portions) and two side walls connecting the two main walls. One end of the rectangular cylindrical portion is sealed with a bottom, and the other end is open as an opening.

The first resin-containing material is not particularly limited, as long as it contains a curable resin and is capable of sealing the laminate (S) containing the unit cells. A known sealing resin used to seal electronic components may be used as the first resin-containing material. The first resin-containing material contains at least a resin. The first resin-containing material may be composed of resin alone, or may be composed of resin and a material other than resin. Examples of resins contained in the first resin-containing material include epoxy resin and silicone resin. The use of epoxy resin strengthens the bonding strength between the two main walls. As a result, swelling of the exterior body under reduced pressure can be particularly suppressed. Because silicone resin has high viscoelasticity, using silicone resin can cushion impacts on the laminate (S) and improve the impact resistance of the battery.

The first resin-containing material may contain a filler dispersed in the resin. Examples of fillers include inorganic fillers such as alumina particles and silica particles.

The first resin-containing material is placed inside the exterior body in a fluid state where it has not yet completely hardened. As long as it is fluid, the first resin-containing material may have begun to harden when it is placed inside the exterior body. There are no limitations on the method for placing the first resin-containing material in the exterior body. For example, the first resin-containing material may be dripped from an opening. Alternatively, a nozzle may be inserted into the exterior body and the first resin-containing material may be filled into the exterior body from the nozzle.

The viscosity of the first resin-containing material placed in the outer casing in step (i) may be 70 Pa·s or less, 20 Pa·s or less, 10 Pa·s or less, 5.0 Pa·s or less, or 3.0 Pa·s or less. The lower limit of this viscosity is not particularly limited, but may be 0.1 Pa·s or more, 0.3 Pa·s or more, or 0.5 Pa·s or more. Setting the viscosity to 20 Pa·s or less (e.g., 10 Pa·s or less or 5.0 Pa or less) makes it easier to place the first resin-containing material in the outer casing and also makes it easier to insert the laminate (S) into the outer casing in step (ii). Using a silicone resin makes it easier to obtain a first resin-containing material with a low viscosity. The viscosity of a resin-containing material containing a silicone resin can be measured using a Brookfield rotational viscometer.

The amount of the first resin-containing material placed in the outer casing in step (i) is an amount that will cover a certain portion of the surface of the laminate (S) when the laminate (S) is inserted into the outer casing in step (ii). For example, this amount is preferably an amount that will cover 30% or more, 50% or more, 70% or more, or 90% or more of the total surface area of the laminate (S) when the laminate (S) is inserted into the outer casing in step (ii). This amount may be an amount that will cover the entire surface of the laminate (S) when the laminate (S) is inserted into the outer casing in step (ii). Alternatively, this amount may be an amount that will cover the end faces of the laminate (S) other than the end face on the opening side of the outer casing.

(Step (ii))
Step (ii) is a step of inserting the laminate (S) including the at least one unit battery into an outer casing, completing the curing of the first resin-containing material, and arranging the cured first resin-containing material between the outer casing and the laminate.

The laminate (S) can be inserted through the opening in the outer casing. After inserting the laminate (S) into the outer casing, the first resin-containing material may be added to the inside of the outer casing. It is preferable that the entire laminate (S) is ultimately covered with the first resin-containing material.

The method for completing the hardening of the first resin-containing material is not limited and is selected depending on the type of resin contained in the first resin-containing material. For example, if a heat-hardening resin is used, the first resin-containing material may be hardened by heating. Furthermore, if a resin that hardens over time is used, the first resin-containing material may be hardened by simply leaving it alone.

In this way, an all-solid-state battery is obtained that includes the laminate (S) fixed within the exterior body by the cured first resin-containing material, and the exterior body.

In step (ii), the laminate (S) may be inserted into the exterior body while the exterior body is pulled outward. This configuration makes it easier to insert the laminate (S) into the exterior body. The method for pulling the exterior body outward is not limited, and the main wall of the exterior body may be adsorbed by vacuum suction or the like and then pulled outward. Alternatively, the opening of the exterior body may be widened using a jig or the like. These methods can also be used in manufacturing method (M2).

In step (ii), the laminate (S) may be inserted into the outer casing with the second resin-containing material applied to the surface of the laminate (S). This configuration makes it easier to insert the laminate (S) into the first resin-containing material. The laminate (S) may be inserted into the outer casing with the applied second resin-containing material not yet cured. Alternatively, the laminate (S) may be inserted into the outer casing with the applied second resin-containing material having completely cured.

The second resin-containing material can be any of the materials exemplified for the first resin-containing material. The first resin-containing material and the second resin-containing material may contain the same resin. This configuration makes it particularly easy to insert the laminate (S) into the first resin-containing material. This configuration also enables strong fixation between the resin-containing material in the outer casing and the laminate (S). The first resin-containing material and the second resin-containing material may be composed of the same material. Alternatively, the first resin-containing material and the second resin-containing material may contain the same resin but be composed of different materials overall. Alternatively, the first resin-containing material and the second resin-containing material may not contain the same resin but be composed of different materials.

In step (ii), the first resin-containing material may be cured while the exterior body is pressurized from the outside. Specifically, the first resin-containing material may be cured while the two main walls of the exterior body are pressed toward the inside of the exterior body. This configuration allows the laminate (S) to be sealed while being pressurized in the stacking direction. Pressurizing the laminate (S) in the stacking direction allows the battery to fully exhibit its performance. Furthermore, this configuration makes it possible to suppress battery expansion under reduced pressure.

In step (ii), when the first resin-containing material is cured while the outer casing is pressurized from the outside, the thickness of the central portion of the outer casing after step (ii) may be smaller than the thickness of the central portion of the outer casing before step (ii) is performed. This configuration allows the laminate (S) to be sealed while being strongly pressurized in the stacking direction. The central portion of the outer casing refers to the central portion of one of the main walls of the outer casing when the wall is viewed from above.

Steps (i) and (ii) may be performed under atmospheric pressure. Alternatively, step (ii) may be performed under reduced pressure. For example, both steps (i) and (ii) may be performed under reduced pressure. Performing step (i) under reduced pressure makes it easier to dispose the first resin-containing material within the exterior body. Performing step (ii) under reduced pressure can prevent voids from forming between the exterior body and the laminate (S). As a result, expansion of the manufactured all-solid-state battery can be prevented when the battery is placed under reduced pressure.

(Second manufacturing method (manufacturing method (M2)))
As described below, in the manufacturing method (M2), the supply of the resin-containing material is started from the lower side of the exterior body with the laminate (S) disposed inside the exterior body. This configuration can prevent large voids from being formed inside the exterior body. As a result, an all-solid-state battery that is less likely to expand even under reduced pressure is obtained. Furthermore, in the manufacturing method (M2), the first resin-containing material can be easily filled into the exterior body, making it easy to manufacture an all-solid-state battery.

The second manufacturing method (manufacturing method (M2)) for an all-solid-state battery includes steps (I) and (II) in this order. These steps are described below.

(Step (I))
Step (I) is a step of placing a laminate (S) including at least one unit cell in an exterior body having an opening. The laminate (S) can be placed inside the exterior body through the opening of the exterior body. The exterior body having an opening can be any of the exterior bodies exemplified in the description of manufacturing method (M1).

In step (I), the laminate (S) having a resin-containing material (second resin-containing material) applied to its surface may be placed inside the exterior packaging. In this case, it becomes easier to fill the resin-containing material (first resin-containing material) used in step (II). The resin-containing material (first resin-containing material) used in step (II) may be the first resin-containing material exemplified in the description of manufacturing method (M1). The resin-containing material (second resin-containing material) used in step (I) may be the second resin-containing material exemplified in the description of manufacturing method (M1).

(Step (II))
Step (II) is a step of disposing the cured resin-containing material between the exterior body and the laminate by starting the supply of a fluid resin-containing material that has not yet been cured from the lower side of the exterior body, filling the exterior body with the resin-containing material, and then completing the curing of the resin-containing material. The method for completing the curing of the resin-containing material is not limited and is selected depending on the type of resin contained in the resin-containing material. For example, when a heat-curable resin is used, the resin-containing material may be cured by heating. Furthermore, when a resin that cures over time is used, the resin-containing material may be cured by simply leaving it.

As described above, the resin-containing material can be the material described as the first resin-containing material in manufacturing method (M1). The fluid state in which the resin-containing material has not yet fully hardened has been described in manufacturing method (M1), so a duplicated description will be omitted. The viscosity of the resin-containing material when filled into the exterior body may be within the range described for the viscosity of the first resin-containing material used in step (i) of manufacturing method (M1).

In step (II), the lower side of the exterior body refers to the side below the vertical center of the interior space of the exterior body when the exterior body is positioned when filled with the resin-containing material. In this case, when the height of the interior space of the exterior body (the vertical length of the interior space of the exterior body) is H, the supply of the resin-containing material may be initiated below a height of H/3 from the bottom of the interior space of the exterior body. Alternatively, the supply of the resin-containing material may be initiated below a height of H/4 from the bottom of the interior space of the exterior body, or below a height of H/5 from the bottom of the interior space of the exterior body.

There are no particular limitations on the method for supplying the resin-containing material from the lower side of the exterior body. For example, a nozzle (e.g., a tubular nozzle) may be inserted into the exterior body through the opening of the exterior body so that the tip of the nozzle reaches the lower side of the exterior body, and the resin-containing material may be supplied from the tip of the nozzle. The nozzle is withdrawn from the exterior body before the resin-containing material has completely hardened. Note that the nozzle may be gradually pulled back toward the opening as the resin-containing material fills the exterior body. At least when supplying the resin-containing material begins, the resin-containing material is supplied from the lower side of the exterior body.

Step (II) is typically performed with the exterior body positioned so that the bottom is facing downward and the opening is facing upward. However, step (II) may also be performed with the exterior body positioned in a different direction. For example, step (II) may be performed with one main wall of the exterior body positioned downward and the other main wall positioned upward. Alternatively, step (II) may be performed with one side wall of the exterior body positioned downward and the other side wall positioned upward. In these cases, the resin-containing material may be filled into the exterior body with the opening partially or entirely covered.

In step (II), the exterior body may be pulled outward while a fluid resin-containing material is filled into the exterior body, and then the resin-containing material may be cured while the exterior body is pressurized from the outside. This configuration allows the laminate (S) to be sealed while being pressurized in the stacking direction. Pressurizing the laminate (S) in the stacking direction allows the battery to fully exhibit its performance. This configuration also makes it possible to suppress battery expansion under reduced pressure.

Steps (I) and (II) may be performed under atmospheric pressure. Alternatively, step (II) may be performed under reduced pressure. Performing step (II) under reduced pressure makes it easier to fill the exterior body with the resin-containing material. Furthermore, performing step (II) under reduced pressure can prevent voids from forming between the exterior body and the laminate (S). As a result, expansion of the produced all-solid-state battery can be prevented when it is placed under reduced pressure.

In manufacturing methods (M1) and (M2), the exterior body may be made of metal. Examples of metals that can be used for the exterior body will be described later.

In manufacturing methods (M1) and (M2), the outer casing may be an outer casing that presses the laminate (S) in the stacking direction. One example of such an outer casing is an outer casing in which, when empty, two main walls are curved so that they convex inward. By using such main walls, the laminate (S) can be pressurized in the stacking direction. When using an outer casing with such main walls, the laminate (S) is inserted into the outer casing while the outer casing (at least the main walls) are pulled outward. In manufacturing methods (M1) and (M2), resin is filled between the outer casing and the laminate (S). This makes it easier for the pressure from the outer casing to be transmitted uniformly to the laminate (S).

When two main walls that are curved convexly inward are used, the shape and size of the outer casing are selected so that when the laminate and resin-containing material are housed inside, the main walls are flatter than before they were housed inside. With this configuration, the main walls can apply pressure to the laminate (S) in the stacking direction.

In another aspect, the present disclosure provides a third manufacturing method (manufacturing method (M3)) for an all-solid-state battery. The third manufacturing method is a manufacturing method for an all-solid-state battery including at least one unit battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. The third manufacturing method includes a step (Ia) of disposing a stack including the at least one unit battery within an exterior body having an opening, and a step (IIa) of disposing the cured resin-containing material between the exterior body and the stack by starting the supply of an incompletely cured, fluid resin-containing material from below a resin filling region within the exterior body, filling the resin-containing material into the resin filling region, and then completing the curing of the resin-containing material.

Step (Ia) is the same as step (I) of manufacturing method (M2), except that the internal space of the exterior body may be partitioned into upper and lower sections, so a redundant description will be omitted. In step (Ia), if a cylindrical body without a bottom (e.g., a rectangular cylindrical body) is used as the exterior body, a partition can be used to separate the internal space of the exterior body. The partition is formed around the periphery of the laminate. In manufacturing method (M3), a rectangular cylindrical body with a bottom may be used as the exterior body, as described in manufacturing method (M2).

Step (IIa) is a step in which the step in step (II) of manufacturing method (M2) in which "supply of incompletely cured, fluid resin-containing material is started from the lower side of the outer casing, the resin-containing material is filled into the outer casing, and then the curing of the resin-containing material is completed" is replaced with the step in which "supply of incompletely cured, fluid resin-containing material is started from the lower side of the resin-filled region of the outer casing, the resin-filled region is filled, and then the curing of the resin-containing material is completed." With the exception of this substitution, the matters described in step (II) are applicable to step (IIa). Furthermore, with the exception of the differences between step (I) and step (Ia) and the differences between step (II) and step (IIa), the matters described in manufacturing method (M2) are applicable to manufacturing method (M3). From one perspective, manufacturing method (M2) can be considered to be included in manufacturing method (M3).

In step (IIa), the resin-filled region refers to the space filled with the resin-containing material. In step (IIa), the lower side of the resin-filled region refers to the side below the vertical center of the resin-filled region when the outer casing is positioned when filling it with the resin-containing material. In this case, if the height of the resin-filled region (the length of the resin-filled region in the vertical direction) is Ha, the supply of the resin-filled material may be started below a height of Ha/3 from the bottom of the resin-filled region. Alternatively, the supply of the resin-filled material may be started below a height of Ha/4 from the bottom of the resin-filled region, or below a height of Ha/5 from the bottom of the resin-filled region.

In manufacturing method (M3), the internal space of the exterior body may be divided into two spaces (a lower space and an upper space) by a partition disposed around the periphery of the laminate. For example, in step (Ia), a laminate having ridges disposed around the periphery as a partition may be disposed within the exterior body, thereby dividing the internal space of the exterior body into two spaces. In this case, two resin-filled regions are formed within the exterior body. In step (IIa), first, the supply of a fluid resin-containing material is initiated from below the upper space (one of the resin-filled regions) to fill the space, and then the resin-containing material is cured. Next, the exterior body is turned upside down, and the supply of a fluid resin-containing material is initiated from below the other space (the other resin-filled region) to fill the space, and then the resin-containing material is cured. In this way, the cured resin-containing material can be disposed in two spaces (two resin-filled regions).

(Components of all-solid-state batteries)
The all-solid-state battery manufactured by manufacturing method (M1) and the all-solid-state battery manufactured by manufacturing method (M2) have basically the same configuration. Examples of components of the all-solid-state batteries manufactured by manufacturing method (M1) and manufacturing method (M2) are described below. However, the following components are merely examples, and other components may be used. Note that, although the following mainly describes an example of an all-solid-state lithium ion battery, other all-solid-state batteries may also be used. The all-solid-state battery is not particularly limited, and may be a known all-solid-state battery.

The all-solid-state battery includes a laminate (S). The laminate (S) includes at least one unit cell (power-generating element). The laminate (S) may include only one unit cell, or may include multiple stacked unit cells. The unit cell includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. The laminate (S) optionally includes a current collector. In an all-solid-state battery, it is preferable that the laminate (S) be pressurized in the stacking direction. Pressurizing the laminate (S) enables it to exhibit high performance.

(Exterior body)
As described above, the exterior body can be a metal case, etc. Examples of metal plates that can form the case include stainless steel plates, carbon steel plates, and aluminum alloy plates.

The thickness of the metal plate that makes up the exterior body can be selected depending on the material, the required pressure resistance, and the material of the metal plate. The thickness of the metal plate that makes up the exterior body may be 0.10 mm or more, or 0.15 mm or more, or 0.60 mm or less, or 0.50 mm or less.

(Positive electrode layer)
The positive electrode layer contains a positive electrode active material and may contain other components as needed. Examples of the other components include known components (binders, conductive materials, etc.) used in the positive electrode layer of all-solid-state batteries. From the viewpoint of increasing the lithium ion conductivity in the positive electrode layer, the positive electrode layer may contain a solid electrolyte exhibiting lithium ion conductivity together with the positive electrode active material. Typically, the positive electrode active material is used in the form of particles (powder).

The positive electrode active material can be a material that can be used as a positive electrode active material for an all-solid-state battery. In the case of an all-solid-state lithium-ion battery, examples of the positive electrode active material include lithium-containing composite oxides and compounds other than oxides. Examples of lithium-containing composite oxides include lithium cobalt oxide, lithium _nickel oxide, lithium _manganese oxide, and other lithium-containing composite oxides ( _{LiNi0.8Co0.15Al0.05O2} , _etc. ). Examples of compounds other than oxides include olivine-based compounds ( _LiMPO4 , etc.), sulfur-containing compounds ( _Li2S , etc.). In the above formula, M represents a transition metal. The positive electrode active material may be used alone or in combination of two or more.

(Negative electrode layer)
The negative electrode layer contains a negative electrode active material and may contain other components as needed. Examples of the other components include known components (binders, conductive materials, etc.) used in the negative electrode layer of all-solid-state batteries. The negative electrode layer may contain a negative electrode active material and a solid electrolyte exhibiting lithium ion conductivity. Typically, the negative electrode active material is used in the form of particles (powder).

The negative electrode active material can be any material that can be used as a negative electrode active material in an all-solid-state battery. In the case of an all-solid-state lithium-ion battery, the negative electrode active material can be a specific material (such as a carbonaceous material, a metal or semimetal element or alloy, or a compound) that can reversibly absorb and release lithium ions. Examples of carbonaceous materials include graphite (natural graphite, artificial graphite, etc.), hard carbon, and amorphous carbon. Examples of metal or semimetal element or alloy include lithium metal or alloy, and elemental silicon. Examples of compounds include oxides (such as titanium oxide and silicon oxide), sulfides, nitrides, hydrates, and silicides (such as lithium silicide). A single negative electrode active material may be used alone, or two or more may be used in combination. For example, silicon oxide and a carbonaceous material may be used in combination. Particles containing graphite particles and amorphous carbon coating the graphite particles may also be used as the negative electrode active material.

(Solid electrolyte layer)
The solid electrolyte layer is disposed between the positive electrode layer and the negative electrode layer. The solid electrolyte layer includes a solid electrolyte and may include other components as needed. Examples of the other components include known components used in solid electrolyte layers of all-solid-state batteries. The solid electrolyte is usually used in the form of particles (powder).

The solid electrolyte can be any material that can be used as a solid electrolyte in an all-solid-state battery, without any particular restrictions. In the case of an all-solid-state lithium-ion battery, the solid electrolyte can be any material that has lithium ion conductivity. Examples of such solid electrolytes include inorganic solid electrolytes such as sulfides (sulfide-based solid electrolytes) and hydrides (hydride-based solid electrolytes).

Examples of sulfides include Li ₂ S-SiS ₂ , Li ₂ SP ₂ S ₅ , Li ₂ S-GeS ₂ , Li ₂ SB ₂ S ₃ , Li ₂ S-Ga ₂ S ₃ , Li ₂ S-Al ₂ S ₃ , Li ₂ S-GeS ₂ -P ₂ S ₅ , Li ₂ S-Al ₂ S ₃ -P ₂ S ₅ , Li ₂ S-P ₂ S ₃ , Li ₂ S-P ₂ S ₃ -P ₂ S ₅ , LiX-Li ₂ S-P ₂ S ₅ , LiX-Li ₂ S-SiS ₂ , LiX-Li ₂ S-B ₂ S ₃ (X: I, Br, or Cl), etc. Examples of the hydrides include LiBH ₄ —LiI-based complex hydrides and LiBH ₄ —LiNH ₂ -based complex hydrides, etc.

(Positive electrode current collector)
A positive electrode current collector is usually disposed on the outside of the positive electrode layer. A metal foil may be used as the positive electrode current collector. Examples of materials for the positive electrode current collector (e.g., metal foil) include aluminum, magnesium, stainless steel, titanium, iron, cobalt, zinc, tin, or alloys thereof. Lead tabs are connected to the positive electrode current collector and the negative electrode current collector as needed.

(Negative electrode current collector)
A negative electrode current collector is usually disposed on the outside of the negative electrode layer. The negative electrode current collector may be a metal foil. Examples of materials for the negative electrode current collector (e.g., metal foil) include copper, nickel, stainless steel, titanium, and alloys thereof.

(Method for forming laminate (S))
The method for forming the laminate (S) is not particularly limited, and may be formed by a known forming method. The laminate (S) is preferably formed using a material that does not contain a liquid component. An example of a method for forming the laminate (S) by such a forming method (dry forming method) will be described below.

First, the materials for the positive electrode layer, solid electrolyte layer, and negative electrode layer are layered in a predetermined order on a metal foil (current collector), and then a current collector (metal foil) is placed on top. Next, the layered materials and metal foil are pressed together (main press) to form a laminate (S). This main press integrates the metal foil and each layer to obtain the laminate (S). The pressure of the main press can be adjusted appropriately depending on the material and thickness, and may be 50 MPa or more and 5000 MPa or less (e.g., 300 MPa or more and 3000 MPa or less). In this way, a laminate (S) having a structure of positive electrode current collector/positive electrode layer/solid electrolyte layer/negative electrode layer/negative electrode current collector is obtained. Note that the laminate (S) may also include layers other than these, such as thin conductive layers.

The materials may be pre-pressed at any stage after the positive electrode layer material is placed, the solid electrolyte layer material is placed, or the negative electrode layer material is placed. The pre-pressing is usually performed at a pressure lower than the pressure used in the main press. There are no particular limitations on the pre-pressing pressure, and it may be in the range of 1 MPa to 10 MPa. To reduce voids in the laminate, at least part of the process of forming the laminate may be performed under reduced pressure.

By forming the laminate (S) using a process of pressing materials that do not contain liquid components, it is possible to obtain an all-solid-state battery that exhibits high performance without the application of high pressure. Methods for arranging materials that do not contain liquid components (dispersion mediums) in layers include electrostatic spraying, squeegee deposition, and electrostatic coating.

When the laminate (S) includes multiple unit batteries, a laminate including one unit battery may be formed by press molding, and then these laminates may be stacked to form the laminate (S). Alternatively, the laminate (S) may be formed by press molding the materials so that multiple unit batteries are stacked.

Examples of embodiments according to the present disclosure will be described below with reference to the drawings. The embodiments described below may be modified based on the above description. The matters described below may also be applied to the above embodiments. Note that the following figures are schematic diagrams and are not drawn to actual scale. In the following figures, some components may be omitted to make the figures easier to see. In the following figures, cross sections of the exterior body may be indicated by lines.

(Embodiment 1)
In Embodiment 1, an example of a manufacturing method (M1) will be described. In the manufacturing method of Embodiment 1, a laminate 110 (laminate (S)) is used. A top view of the laminate 110 is shown in FIG. 1A. A cross-sectional view taken along line IB-IB in FIG. 1A is shown in FIG. 1B.

The laminate 110 includes a positive electrode current collector 111, a unit battery 113, and a negative electrode current collector 112. The unit battery 113 includes a positive electrode layer 113a, a solid electrolyte layer 113b, and a negative electrode layer 113c. These layers and current collectors are stacked in the stacking direction SD. The laminate 110 may be formed by the process described above.

A positive electrode lead tab 121 and a negative electrode lead tab 122 protrude from the laminate 110. The positive electrode lead tab 121 may be integral with the positive electrode current collector 111, or may be a lead tab connected to the positive electrode current collector 111. The negative electrode lead tab 122 may be integral with the negative electrode current collector 112, or may be a lead tab connected to the negative electrode current collector 112.

First, as shown in FIG. 2A, a resin-containing material (first resin-containing material) 201a that has not yet completely hardened and has fluidity is placed inside an exterior body 120 having an opening (step (i)). A cross-sectional view of the exterior body 120 taken along line IIIA-IIIA in FIG. 2A is shown in FIG. 3A.

The exterior body 120 includes a rectangular tube portion 120a and a bottom portion 120b that seals one end of the rectangular tube portion 120a. The other end of the rectangular tube portion 120a is open as an opening 120t. The rectangular tube portion 120a is composed of two opposing main walls 120am and two side walls 120as that connect the two main walls 120am. Figure 3B shows a cross-sectional view of another example of the exterior body 120. When the exterior body 120 shown in Figure 3B is empty, the two main walls 120am are curved so that they convex inward. In other words, the main walls 120am have a ridge-like shape that convex inward. Using the exterior body 120 makes it possible to apply pressure to the stack 110 in the stacking direction SD.

Next, the laminate 110 is inserted into the exterior body, and then the curing of the resin-containing material 201a is completed (step (ii)). As a result, as shown in FIG. 2B, the cured resin-containing material (first resin-containing material) 201b is disposed between the exterior body 120 and the laminate 110. In this manner, the all-solid-state battery 100 is obtained. The positive electrode lead tab 121 and the negative electrode lead tab 122 protrude from the cured resin-containing material 201b.

As described above, in step (ii), the laminate 110 may be inserted into the exterior body 120 with the exterior body 120 pulled outward. Figure 3C schematically shows the cross-sectional shape of the exterior body 120 when the exterior body 120 is pulled outward. The state shown in Figure 3C is a state in which the center of the main wall 120am in the width direction WD is pulled outward.

As described above, in step (ii), the resin-containing material 201a may be cured while the outer casing is pressurized from the outside. Specifically, the resin-containing material 201a may be cured while the main wall 120am is pressurized inward.

(Embodiment 2)
In embodiment 2, an example of the manufacturing method (M2) will be described. In the manufacturing method of embodiment 2, a laminate 110 (laminate (S)) is used. The laminate 110 has been described in embodiment 1, so a duplicated description will be omitted.

First, as shown in FIG. 4A, the laminate 110 is placed inside an exterior body 120 having an opening 120t (step (I)). The exterior body 120 has been described in embodiment 1, so a duplicate description will be omitted.

Next, the supply of fluid resin-containing material that has not yet cured is started from the lower side inside the exterior body 120 to fill the interior of the exterior body 120 with the resin-containing material, and then the curing of the resin-containing material is completed (step (II)). As a result, as shown in FIG. 4B, the cured resin-containing material 201b is disposed between the exterior body 120 and the laminate 110. In this manner, the all-solid-state battery 100 is obtained. The positive electrode lead tab 121 and the negative electrode lead tab 122 protrude from the cured resin-containing material 201b.

The resin-containing material may be filled into the exterior body 120 using a nozzle (tube) 210, as shown in FIG. 5. The height H of the exterior body 120 in the arrangement shown in FIG. 5 is shown in FIG. 5. The supply of the resin-containing material begins from the lower side of the internal space of the exterior body 120, i.e., from a position lower than a height of H/2 from the inner surface of the bottom 120b. Therefore, at least when the supply of the resin-containing material begins, the nozzle 210 is positioned so that the tip of the nozzle 210 reaches the lower side of the exterior body 120, and the resin-containing material is supplied into the exterior body 120 from the tip of the nozzle 210. The position of the nozzle 210 (the position of the tip of the nozzle 210) may remain the same until the filling of the resin-containing material is complete. Alternatively, the nozzle 210 may be gradually raised as the resin-containing material is filled.

Figures 4A and 4B illustrate an example in which steps (I) and (II) are performed with the bottom 120b of the exterior body 120 positioned downward. However, steps (I) and (II) may also be performed with a part of the exterior body 120 other than the bottom 120b positioned downward.

Figure 6 shows an example where one of the main walls 120am is positioned downward. The height H of the exterior body 120 in the position shown in Figure 6 is also shown in Figure 6. When step (II) is performed in the position shown in Figure 6, it may be performed with the opening 120t sealed with the lid 130. In this case, step (II) may be performed by forming a through-hole on the lower side of the exterior body 120 in the position shown in Figure 6, and filling the interior of the exterior body 120 with the resin-containing material through the through-hole. Alternatively, a gap or through-hole may be formed on the lower side of the lid 130, and the interior of the exterior body 120 may be filled with the resin-containing material through the gap or through-hole.

Note that while Figures 4A and 4B show an example in which the bottom 120b is arranged parallel to the horizontal plane, the bottom 120b may be tilted relative to the horizontal plane. Also, while Figure 6 shows an example in which the main wall 120am is arranged parallel to the horizontal plane, the main wall 120am may be tilted relative to the horizontal plane. In either case, the height of the exterior body refers to the length of the exterior body along the vertical direction.

(Additional Note)
The above description discloses the following invention examples.
(Example 1)
A method for manufacturing an all-solid-state battery including at least one unit battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, comprising:
Step (i) of disposing a first resin-containing material having fluidity and not yet cured in an exterior body having an opening;
and (ii) completing curing of the first resin-containing material after inserting a laminate including the at least one unit battery into the exterior body, and disposing the cured first resin-containing material between the exterior body and the laminate.
(Example 2)
The manufacturing method according to Example 1, wherein in step (ii), the laminate is inserted into the exterior body while the exterior body is pulled outward.
(Example 3)
The manufacturing method according to Invention Example 1 or 2, wherein in step (ii), the laminate is inserted into the outer casing in a state where a second resin-containing material is applied to the surface of the laminate.
(Example 4)
The manufacturing method described in Invention Example 3, wherein the first resin-containing material and the second resin-containing material contain the same resin.
(Example 5)
The manufacturing method according to any one of Examples 1 to 4, wherein in step (ii), the first resin-containing material is cured while the outer casing is pressurized from the outside.
(Example 6)
A manufacturing method described in Example 5, wherein the thickness of the central portion of the outer casing after step (ii) is smaller than the thickness of the central portion of the outer casing before step (ii) is performed.
(Example 7)
The production method of any one of Invention Examples 1 to 6, wherein the step (i) and the step (ii) are carried out under reduced pressure.
(Example 8)
A method for manufacturing an all-solid-state battery including at least one unit battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, comprising:
a step (I) of disposing a stack including at least one unit battery in an exterior body having an opening;
and (II) supplying a resin-containing material that has not yet completely cured and has fluidity from a lower side of the exterior body to fill the interior of the exterior body, and then completing the curing of the resin-containing material, thereby disposing the cured resin-containing material between the exterior body and the laminate.
(Example 9)
In the step (II),
The manufacturing method described in Example 8 of the present invention, in which the resin-containing material having fluidity is filled into the outer casing while the outer casing is pulled outward, and then the resin-containing material is hardened while the outer casing is pressurized from the outside.
(Example 10)
The production method according to Invention Example 8 or 9, wherein step (II) is carried out under reduced pressure.
(Example 11)
The manufacturing method according to any one of Examples 1 to 10, wherein the exterior body is made of metal.
(Example 12)
A manufacturing method described in Example 11 of the present invention, wherein the outer casing is an outer casing that presses the laminate in the stacking direction.

This disclosure can be used in manufacturing methods for all-solid-state batteries.

100: All-solid battery 110: Laminated body 113: Unit battery 113a: Positive electrode layer 113b: Solid electrolyte layer 113c: Negative electrode layer 120: Exterior body 120a: Square tube portion 120am: Main wall 120as: Side wall 120b: Bottom portion 120t: Opening portion 201a :Resin-containing material (first resin-containing material, before curing is completed)
201b: Resin-containing material (first resin-containing material, after curing is completed)
210: Nozzle

Claims (11)

A method for manufacturing an all-solid-state battery including at least one unit battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, comprising:
Step (i) of disposing a first resin-containing material having fluidity and not yet cured in an exterior body having an opening;
and (ii) a step of completing curing of the first resin-containing material after inserting a stack including the at least one unit battery into the exterior body, and disposing the cured first resin-containing material between the exterior body and the stack ;
In the step (ii), the laminate is inserted into the exterior body in a state where the exterior body is pulled outward . The manufacturing method according to claim 1 , wherein in the step (ii), the laminate is inserted into the exterior body in a state where a second resin-containing material is applied to a surface of the laminate. The manufacturing method according to claim 2 , wherein the first resin-containing material and the second resin-containing material contain the same resin. A method for manufacturing an all-solid-state battery including at least one unit battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, comprising:
Step (i) of disposing a first resin-containing material having fluidity and not yet cured in an exterior body having an opening;
and (ii) a step of completing curing of the first resin-containing material after inserting a stack including the at least one unit battery into the exterior body, and disposing the cured first resin-containing material between the exterior body and the stack ;
In the step (ii), the first resin-containing material is cured in a state in which the exterior body is pressurized from the outside . The manufacturing method according to claim 4 , wherein the thickness of the central portion of the exterior body after the step (ii) is smaller than the thickness of the central portion of the exterior body before the step (ii) is performed. The method according to claim 1 or 4 , wherein the steps (i) and (ii) are carried out under reduced pressure. A method for manufacturing an all-solid-state battery including at least one unit battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, comprising:
a step (I) of disposing a stack including at least one unit battery in an exterior body having an opening;
and (II) supplying a resin-containing material that has not yet completely cured and has fluidity from a lower side of the exterior body to fill the interior of the exterior body, and then completing the curing of the resin-containing material, thereby disposing the cured resin-containing material between the exterior body and the laminate. In the step (II),
The manufacturing method according to claim 7, wherein the resin-containing material having fluidity is filled into the exterior body while the exterior body is pulled outward, and then the resin-containing material is hardened while the exterior body is pressurized from the outside. The method according to claim 7 or 8 , wherein step (II) is carried out under reduced pressure. The manufacturing method according to claim 1 , 4 , or 7 , wherein the exterior body is made of metal. The manufacturing method according to claim 10 , wherein the outer casing applies pressure to the laminate in a stacking direction.