JP7729328B2 - Conductive carbon material dispersant for energy devices, conductive carbon material dispersion for energy devices, composition for forming an electrode for energy devices and method for producing the same, energy device electrode, and energy device - Google Patents

Description

The present disclosure relates to a conductive carbon material dispersion for energy devices, a conductive carbon material dispersion for energy devices, a composition for forming an energy device electrode and a method for producing the same, an energy device electrode, and an energy device.

Lithium-ion secondary batteries, which are non-aqueous electrolyte energy devices with high energy density, are widely used as power sources for portable information terminals such as notebook computers, mobile phones, and PDAs (Personal Digital Assistants).

In lithium-ion secondary batteries, the active material for the negative electrode is typically a carbon material with a multilayer structure that allows lithium ions to be inserted between layers (forming a lithium intercalation compound) and released. The active material for the positive electrode is typically a lithium-containing metal composite oxide. Electrodes for lithium-ion secondary batteries are manufactured by kneading these active materials, a binder resin, a carbon material such as carbon black, and a solvent (N-methyl-2-pyrrolidone, water, etc.) to prepare a slurry. This slurry is then applied to one or both sides of a metal foil current collector using a transfer roll or similar device. The solvent is then dried to remove the mixture layer, and the resulting mixture is then compression-molded using a roll press or similar device.

Carbon materials are added to electrodes to provide electronic conductivity. In recent years, the trend toward higher capacity lithium-ion secondary batteries has led to a reduction in the amount of carbon material added, which does not contribute to higher capacity. To reduce the amount of carbon material added, the particle size of the carbon material is being reduced.

Japanese Patent Application Laid-Open No. 2012-59466 proposes a kneading process for efficiently, stably, and uniformly dispersing a positive electrode mixture containing a carbon material.
Furthermore, WO 2012/014616 proposes a carbon slurry containing a polyvinylpyrrolidone-based polymer and a nonionic surfactant as a dispersant. Dispersants such as a polyvinylpyrrolidone-based polymer and a nonionic surfactant are effective for dispersing carbon materials.

In order to reduce the amount of carbon material added, it is effective to use a carbon material with a small average particle size. However, the kneading process described in JP 2012-59466 A may not be effective for carbon materials with a small average particle size.
Furthermore, although the dispersant described in WO 2012/014616 is effective in dispersing carbon materials, it is prone to side reactions such as oxidative decomposition within the battery, which may lead to other problems such as a decrease in battery capacity and gas generation.
Therefore, there has been a demand for a dispersant that is effective in dispersing carbon materials with small average particle sizes.
The present disclosure has been made in view of the above-described conventional circumstances, and aims to provide a conductive carbon material dispersant for energy devices that has excellent dispersibility. Furthermore, the present disclosure aims to provide a conductive carbon material dispersion for energy devices that uses the dispersant, a composition for forming an energy device electrode and a method for producing the same, an energy device electrode, and an energy device.

Specific means for achieving the above object are as follows.
<1> A conductive carbon material dispersant for energy devices, comprising a resin including a structural unit derived from a nitrile group-containing monomer.
<2> The conductive carbon material dispersant for an energy device according to <1>, wherein the resin further contains a structural unit derived from a monomer represented by the following formula (I):

[In formula (I), R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom or a monovalent hydrocarbon group, and n represents an integer of 1 to 50.]
<3> The conductive carbon material dispersant for an energy device according to <1> or <2>, wherein the structural unit derived from the nitrile group-containing monomer is contained in a main chain of the resin.
<4> The conductive carbon material dispersant for an energy device according to any one of <1> to <3>, wherein a mass ratio of the structural unit derived from the nitrile group-containing monomer in the resin is more than 80 mass % and 100 mass % or less.
<5> A conductive carbon material dispersion for an energy device, comprising a conductive carbon material, the conductive carbon material dispersant for an energy device according to any one of <1> to <4>, and a solvent.
<6> The conductive carbon material dispersion for an energy device according to <5>, wherein the conductive carbon material has an average primary particle size of 50 nm or less.
<7> The conductive carbon material dispersion for an energy device according to <5> or <6>, wherein the conductive carbon material contains carbon black.
<8> The conductive carbon material dispersion for an energy device according to any one of <5> to <7>, wherein the conductive carbon material has an average particle size of 0.3 μm to 3 μm.
<9> The conductive carbon material dispersion for an energy device according to <5>, wherein the conductive carbon material contains carbon fibers.
<10> The conductive carbon material dispersion for an energy device according to any one of <5> to <9>, wherein the solvent contains at least one of N-methyl-2-pyrrolidone and γ-butyrolactone.
<11> A composition for forming an energy device electrode, comprising: a binder resin; an active material; a conductive carbon material; a dispersant for dispersing the conductive carbon material; and a solvent, wherein the dispersant contains the conductive carbon material dispersant for an energy device according to any one of <1> to <4>.
<12> A method for producing a composition for forming an energy device electrode, comprising: a step of mixing an active material with the conductive carbon material dispersion for an energy device according to any one of <5> to <10> to prepare an active material dispersion; and a step of adding a binder resin to the active material dispersion.
<13> The method for producing a composition for forming an energy device electrode according to <12>, further comprising adding a conductive carbon material to the active material dispersion liquid.
<14> A current collector;
an electrode mixture layer provided on at least one surface of the current collector and formed using a composition for forming an energy device electrode produced by the method for producing a composition for forming an energy device electrode according to <12> or <13>;
An energy device electrode having:
<15> An energy device comprising the energy device electrode according to <14>.

The present disclosure makes it possible to provide a conductive carbon material dispersant for energy devices with excellent dispersibility. Furthermore, the present disclosure makes it possible to provide a conductive carbon material dispersion for energy devices using this dispersant, a composition for forming an energy device electrode and a method for producing the same, an energy device electrode, and an energy device.

FIG. 1 is a cross-sectional view of a lithium-ion secondary battery to which the present disclosure is applied.

The following describes in detail the forms for implementing the present disclosure. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and do not limit the present disclosure.

In the present disclosure, the term "process" includes not only a process that is independent of other processes, but also a process that cannot be clearly distinguished from other processes as long as the purpose of the process is achieved.
In the present disclosure, numerical ranges indicated using "to" include the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.
In the present disclosure, each component may contain multiple substances corresponding to the component. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified.
In the present disclosure, the particles corresponding to each component may contain multiple types of particles. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.
In the present disclosure, the terms "layer" and "film" include cases where the layer or film is formed over the entire area when the area in which the layer or film is present is observed, as well as cases where the layer or film is formed over only a portion of the area.
In this disclosure, the term "lamination" refers to stacking layers, and two or more layers may be bonded together, or two or more layers may be detachable.
In the present disclosure, "(meth)acrylic" means at least one of acrylic and methacrylic, and "(meth)acrylate" means at least one of acrylate and methacrylate.
In the present disclosure, the average thickness of a layer or film is a value obtained by measuring the thickness of the layer or film at five points and calculating the arithmetic mean value.
The thickness of a layer or film can be measured using a micrometer or the like. In the present disclosure, when the thickness of a layer or film can be measured directly, it is measured using a micrometer. On the other hand, when the thickness of a single layer or the total thickness of multiple layers is measured, it may be measured by observing a cross section of the object to be measured using an electron microscope.

<Conductive carbon material dispersant for energy devices>
The conductive carbon material dispersant for energy devices of the present disclosure (hereinafter may be simply referred to as the "dispersant") contains a resin including structural units derived from a nitrile group-containing monomer (hereinafter may be referred to as the "specific nitrile resin").
As a result of extensive research, the present inventors have found that the dispersant of the present disclosure has excellent dispersibility for carbon materials such as carbon black, and have completed the present invention.

The components that make up the dispersant of the present disclosure are described in detail below.

-Nitrile group-containing monomer-
The nitrile group-containing monomer that is the source of the structural unit derived from the nitrile group-containing monomer contained in the specific nitrile resin is not particularly limited, and examples thereof include acrylic nitrile group-containing monomers such as acrylonitrile and methacrylonitrile, cyanide nitrile group-containing monomers such as α-cyanoacrylate and dicyanovinylidene, and fumaronitrile nitrile group-containing monomers.
Among these, acrylonitrile is preferred in terms of ease of polymerization, cost performance, further improvement in dispersibility of the conductive carbon material, etc. The ratio of acrylonitrile to the nitrile group-containing monomer is preferably 5% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and even more preferably 70% by mass to 100% by mass. These nitrile group-containing monomers may be used alone or in combination of two or more.
When acrylonitrile and methacrylonitrile are used in combination as the nitrile group-containing monomer, the content of acrylonitrile is, for example, preferably 5% by mass to 95% by mass, and more preferably 50% by mass to 95% by mass, based on the total amount of the nitrile group-containing monomer.
The proportion by mass of the structural units derived from the nitrile group-containing monomer in the specific nitrile resin may be more than 80% by mass and 100% by mass or less, may be 90% by mass to 100% by mass, or may be 92% by mass to 100% by mass.

The structural unit derived from the nitrile group-containing monomer is preferably contained in the main chain of the specific nitrile resin. In this disclosure, the "main chain" of the specific nitrile resin refers to the portion where monomers are linked by polymerization during the synthesis of the specific nitrile resin, if the specific nitrile resin is linear. For example, in the case of a polymer obtained by polymerizing acrylonitrile, it refers to the alkylene portion where vinyl groups in the acrylonitrile are linked by polymerization. Furthermore, if the specific nitrile resin is a graft polymer, the "main chain" of the specific nitrile resin refers to the portion of the copolymer that forms the backbone.

-Monomer represented by formula (I)-
The specific nitrile resin may contain a structural unit derived from a monomer represented by the following general formula (I) as necessary.

In formula (I), R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom or a monovalent hydrocarbon group, and n represents an integer of 1 to 50.

In formula (I), n is an integer of 1 to 50, and in one embodiment, n is preferably an integer of 2 to 30, more preferably an integer of 2 to 15, and even more preferably an integer of 2 to 10. In another embodiment, n is preferably an integer of 1 to 30, more preferably an integer of 1 to 15, and even more preferably an integer of 1 to 10.
In formula (I), _R2 is a hydrogen atom or a monovalent hydrocarbon group, and for example, is preferably a monovalent hydrocarbon group, more preferably a monovalent hydrocarbon group having 1 to 50 carbon atoms, even more preferably a monovalent hydrocarbon group having 1 to 25 carbon atoms, and particularly preferably a monovalent hydrocarbon group having 1 to 12 carbon atoms.
Examples of hydrocarbon groups include alkyl groups and phenyl groups. _R2 is particularly preferably an alkyl group having 1 to 12 carbon atoms or a phenyl group. The alkyl group may be linear, branched, or cyclic.
In the alkyl group and phenyl group represented by _R2 , some of the hydrogen atoms may be substituted with a substituent. When _R2 is an alkyl group, examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, a nitrogen atom-containing substituent, a phosphorus atom-containing substituent, and an aromatic ring. When _R2 is a phenyl group, examples of the substituent include a halogen atom such as a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, a nitrogen atom-containing substituent, a phosphorus atom-containing substituent, an aromatic ring, and a cycloalkyl group having 3 to 10 carbon atoms.

The monomer represented by formula (I) may be a commercially available product or a synthetic product. Specific examples of commercially available monomers represented by formula (I) include 2-methoxyethyl acrylate, ethoxydiethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate EC-A), methoxytriethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate MTG-A and Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester AM-30G), methoxypoly(n=9)ethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate 130-A and Shin-Nakamura Chemical Co., Ltd., trade name: N NK Ester AM-90G), methoxypoly(n=13) ethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester AM-130G), methoxypoly(n=23) ethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester AM-230G), octoxypoly(n=18) ethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester A-OC-18E), phenoxydiethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate P-200A and Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester AMP-20GY), phenoxypoly (n=6) ethylene glycol acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester AMP-60G), nonylphenol EO adduct (n=4) acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate NP-4EA), nonylphenol EO adduct (n=8) acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate NP-8EA), methoxydiethylene glycol methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Ester MC and Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester M-20 G), methoxytriethylene glycol methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Ester MTG), methoxypoly(n=9) ethylene glycol methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Ester 130MA and manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester M-90G), methoxypoly(n=23) ethylene glycol methacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK Ester M-230G), and methoxypoly(n=30) ethylene glycol methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Ester 041MA).
Among these, methoxypoly(n=9)ethylene glycol acrylate (a compound in which _R1 is a hydrogen atom, R2 is a methyl group, and n is ₉ in general formula (I)) is more preferred from the viewpoint of reactivity when copolymerized with a nitrile group-containing monomer. These monomers represented by general formula (I) may be used alone or in combination of two or more.

-Monomer represented by formula (II)-
The specific nitrile resin may contain a structural unit derived from a monomer represented by formula (II) as necessary. The monomer represented by formula (II) used in the present disclosure is not particularly limited.

In formula (II), _R3 represents a hydrogen atom or a methyl group, and _R4 represents an alkyl group having 4 to 100 carbon atoms.

In formula (II), _R4 is an alkyl group having 4 to 100 carbon atoms, preferably an alkyl group having 4 to 50 carbon atoms, more preferably an alkyl group having 6 to 30 carbon atoms, and even more preferably an alkyl group having 8 to 15 carbon atoms.
The alkyl group represented by _R4 may be linear, branched, or cyclic.
In the alkyl group represented by _R4 , some of the hydrogen atoms may be substituted with a substituent. Examples of the substituent include halogen atoms such as fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, substituents containing a nitrogen atom, substituents containing a phosphorus atom, and aromatic rings. For example, examples of the alkyl group represented by _R4 include linear, branched, or cyclic saturated alkyl groups, as well as halogenated alkyl groups such as fluoroalkyl groups, chloroalkyl groups, bromoalkyl groups, and iodinated alkyl groups.

The monomer represented by formula (II) may be a commercially available product or a synthetic product. Specific examples of the monomer represented by formula (II) that is commercially available include (meth)acrylic acid esters containing an alkyl group having 4 to 100 carbon atoms, such as n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, hexadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate.
When R ₄ is a fluoroalkyl group, examples of the fluoroalkyl group include 1,1-bis(trifluoromethyl)-2,2,2-trifluoroethyl acrylate, 2,2,3,3,4,4,4-heptafluorobutyl acrylate, 2,2,3,4,4,4-hexafluorobutyl acrylate, nonafluoroisobutyl acrylate, 2,2,3,3,4,4,5,5-octafluoropentyl acrylate, 2,2, 3,3,4,4,5,5,5-nonafluoropentyl acrylate, 2,2,3,3,4,4,5,5,6,6,6-undecafluorohexyl acrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl acrylate, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl acrylate acrylate compounds such as 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-nonadecafluorodecyl acrylate, nonafluoro-t-butyl methacrylate, 2,2,3,3,4,4,4-heptafluorobutyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 2,2,3,3,4,4,5 , 5,6,6,7,7-dodecafluoroheptyl methacrylate, heptadecafluorooctyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl methacrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluorononyl methacrylate, and other methacrylate compounds.
These monomers represented by general formula (II) may be used singly or in combination of two or more.

-Carboxy group-containing monomer-
The specific nitrile resin may contain a structural unit derived from a carboxy group-containing monomer, if necessary.
Specific examples of the carboxy group-containing monomer are not particularly limited, and include acrylic carboxy group-containing monomers such as acrylic acid and methacrylic acid, crotonic carboxy group-containing monomers such as crotonic acid, maleic carboxy group-containing monomers such as maleic acid and its anhydride, itaconic carboxy group-containing monomers such as itaconic acid and its anhydride, and citraconic carboxy group-containing monomers such as citraconic acid and its anhydride.

-Other monomers-
The specific nitrile resin may contain, as necessary, a structural unit derived from a monomer other than the structural unit derived from the monomer represented by general formula (I), the structural unit derived from the monomer represented by general formula (II), and the structural unit derived from the carboxy group-containing monomer.
The other monomers are not particularly limited and include (meth)acrylic acid esters containing an alkyl group having 1 to 3 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate, vinyl halides such as vinyl chloride, vinyl bromide, and vinylidene chloride, maleimide, phenylmaleimide, (meth)acrylamide, styrene, α-methylstyrene, vinyl acetate, sodium (meth)allyl sulfonate, sodium (meth)allyloxybenzenesulfonate, sodium styrenesulfonate, 2-acrylamido-2-methylpropanesulfonic acid and salts thereof, etc. These other monomers may be used alone or in combination of two or more.

- Ratio of structural units derived from each monomer -
The ratio of the structural units derived from the above-mentioned monomers contained in the specific nitrile resin is not particularly limited.
The ratio of the structural units derived from the nitrile group-containing monomer to the total of the structural units derived from the above-mentioned monomers contained in the specific nitrile resin may be 50 mol% to 100 mol%, 80 mol% to 100 mol%, 90 mol% to 100 mol%, or 95 mol% to 100 mol%.
When the ratio of the structural units derived from the nitrile group-containing monomer to the total of the structural units derived from the respective monomers is 90 mol % to 100 mol %, n in the monomer represented by formula (I) may represent an integer of 2 to 50.
The ratio of the structural units derived from the carboxyl group-containing monomer and containing a carboxyl group to 1 mole of the structural units derived from the nitrile group-containing monomer may be 0.005 moles or less, or may be 0.001 moles or less.
The ratio of the structural units derived from the monomer represented by formula (I) to 1 mole of the structural units derived from the nitrile group-containing monomer may be, for example, 0.001 mol to 0.2 mol, 0.003 mol to 0.05 mol, or 0.005 mol to 0.035 mol. When the ratio of the structural units derived from the monomer represented by formula (I) to 1 mole of the structural units derived from the nitrile group-containing monomer is 0.001 mol to 0.2 mol, the ionic conductivity of the electrode mixture layer containing the dispersant of the present disclosure tends to be improved.

When the specific nitrile resin contains structural units derived from a monomer represented by formula (II), the ratio of structural units derived from the monomer represented by formula (II) to 1 mole of structural units derived from the nitrile group-containing monomer may be, for example, 0.001 mol to 0.2 mol, 0.003 mol to 0.05 mol, or 0.005 mol to 0.02 mol.

When the specific nitrile resin contains structural units derived from a monomer represented by formula (I) and structural units derived from a monomer represented by formula (II), the ratio of the total of the structural units derived from the monomer represented by formula (I) and the structural units derived from the monomer represented by formula (II) per mole of structural units derived from the nitrile group-containing monomer may be, for example, 0.001 to 0.2 moles, 0.003 to 0.05 moles, or 0.005 to 0.035 moles.

When the specific nitrile resin contains structural units derived from other monomers, the ratio of structural units derived from other monomers to 1 mole of structural units derived from the nitrile group-containing monomer may be, for example, 0.005 mol to 0.1 mol, 0.01 mol to 0.06 mol, or 0.03 mol to 0.05 mol.

-Method for producing specific nitrile resin-
The method for producing the specific nitrile resin is not particularly limited. Polymerization methods such as underwater precipitation polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, and solution polymerization can be applied. Underwater precipitation polymerization is preferred in terms of ease of resin synthesis and ease of post-treatment such as recovery and purification.
The aqueous precipitation polymerization will be described in detail below.

- Polymerization initiator -
As the polymerization initiator for carrying out the underwater precipitation polymerization, it is preferable to use a water-soluble polymerization initiator in terms of the polymerization initiation efficiency and the like.
Examples of the water-soluble polymerization initiator include persulfates such as ammonium persulfate, potassium persulfate, and sodium persulfate; water-soluble peroxides such as hydrogen peroxide; water-soluble azo compounds such as 2,2′-azobis(2-methylpropionamidine hydrochloride); and oxidation-reduction (redox) initiators obtained by combining an oxidizing agent such as a persulfate with a reducing agent such as sodium hydrogen sulfite, ammonium hydrogen sulfite, sodium thiosulfate, and hydrosulfite; and a polymerization accelerator such as sulfuric acid, iron sulfate, and copper sulfate.
Among these, persulfates, water-soluble azo compounds, etc. are preferred in terms of ease of resin synthesis, etc. Among persulfates, ammonium persulfate is particularly preferred.
In addition, when acrylonitrile is selected as the nitrile group-containing monomer and methoxypoly(n=9)ethylene glycol acrylate is selected as the monomer represented by formula (I) and precipitation polymerization is carried out in water, both monomers are water-soluble, so that a water-soluble polymerization initiator acts effectively and polymerization starts smoothly. As the polymerization proceeds, the polymer precipitates, so the reaction system becomes suspended, and finally, a specific nitrile resin with little unreacted matter is obtained in high yield.
The polymerization initiator is preferably used in an amount of, for example, 0.001 mol % to 5 mol %, and more preferably 0.003 mol % to 2 mol %, relative to the total amount of monomers used in the synthesis of the specific nitrile resin.

- Chain transfer agent -
When carrying out underwater precipitation polymerization, a chain transfer agent can be used for the purpose of adjusting the molecular weight, etc. Examples of the chain transfer agent include mercaptan compounds such as thioglycol, carbon tetrachloride, and α-methylstyrene dimer. Among these, α-methylstyrene dimer is preferred because of its low odor, etc.

-solvent-
When carrying out underwater precipitation polymerization, a solvent other than water may be added as necessary, for example, to adjust the particle size of the precipitated resin.
Examples of the solvent other than water include amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; ureas such as N,N-dimethylethyleneurea, N,N-dimethylpropyleneurea, and tetramethylurea; lactones such as γ-butyrolactone and γ-caprolactone; carbonates such as propylene carbonate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate, ethyl cellosolve acetate, and ethyl carbitol acetate; glymes such as diglyme, triglyme, and tetraglyme; hydrocarbons such as toluene, xylene, and cyclohexane; sulfoxides such as dimethyl sulfoxide; sulfones such as sulfolane; and alcohols such as methanol, isopropanol, and n-butanol. These solvents may be used alone or in combination of two or more.

- Polymerization conditions -
The underwater precipitation polymerization is carried out, for example, by introducing the monomers into a solvent, maintaining the polymerization temperature at preferably 0°C to 100°C, more preferably 30°C to 90°C, and for preferably 1 hour to 50 hours, more preferably 2 hours to 12 hours.
If the polymerization temperature is 0° C. or higher, the polymerization reaction tends to be accelerated. Also, if the polymerization temperature is 100° C. or lower, even when water is used as a solvent, water tends not to evaporate, making it difficult for polymerization to occur.
In particular, since the heat of polymerization of the nitrile group-containing monomer tends to be large, it is preferable to carry out the polymerization while adding the nitrile group-containing monomer dropwise to the solvent.

The weight average molecular weight of the specific nitrile resin is preferably 10,000 to 1,000,000, more preferably 100,000 to 800,000, and even more preferably 250,000 to 700,000.
In the present disclosure, the weight average molecular weight refers to a value measured by the following method.
The sample to be measured is dissolved in N-methyl-2-pyrrolidone, and insoluble matter is removed by passing it through a PTFE (polytetrafluoroethylene) filter [Kurabo Industries, Ltd., HPLC (high performance liquid chromatography) pretreatment, Chromatodisc, model number: 13N, pore size: 0.45 μm]. The weight average molecular weight is measured using GPC [pump: L6200 Pump (Hitachi, Ltd.), detector: differential refractive index detector L3300 RI Monitor (Hitachi, Ltd.), columns: TSKgel-G5000HXL and TSKgel-G2000HXL (total of two) (both manufactured by Tosoh Corporation) connected in series, column temperature: 30°C, eluent: N-methyl-2-pyrrolidone, flow rate: 1.0 mL/min, standard substance: polystyrene].

The acid value of the specific nitrile resin is preferably 0 mgKOH/g to 70 mgKOH/g, more preferably 0 mgKOH/g to 20 mgKOH/g, and even more preferably 0 mgKOH/g to 5 mgKOH/g.
In the present disclosure, the acid value refers to a value measured by the following method.
First, 1 g of the object to be measured is weighed out, and 30 g of acetone is added to the object to dissolve it. Next, an appropriate amount of phenolphthalein, an indicator, is added to the solution of the object to be measured, and titration is performed using a 0.1 N KOH aqueous solution. The acid value is then calculated from the titration results using the following formula (A) (where Vf represents the titration amount (mL) of phenolphthalein, Wp represents the mass (g) of the object solution, and I represents the proportion (mass%) of nonvolatile content in the object solution).
Acid value (mgKOH/g) = 10 x Vf x 56.1/(Wp x I) (A)
The non-volatile content of the solution to be measured is calculated from the weight of the residue after measuring approximately 1 mL of the solution to be measured into an aluminum pan and drying it on a hot plate heated to 160°C for 15 minutes.

The dispersant of the present disclosure may contain unreacted monomers used in synthesizing the specific nitrile resin as components other than the specific nitrile resin. The content of unreacted monomers contained in the dispersant of the present disclosure is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

<Conductive carbon material dispersion for energy devices>
The conductive carbon material dispersion for an energy device according to the present disclosure (hereinafter, sometimes simply referred to as "dispersion") contains a conductive carbon material, the dispersant according to the present disclosure, and a solvent.

The components that make up the dispersion of the present disclosure are described in detail below.

-Conductive carbon materials-
The conductive carbon material contained in the dispersion of the present disclosure is not particularly limited as long as it exhibits conductivity.
As the conductive carbon material, carbon black, graphite, carbon nanotubes, carbon fibers, etc. can be used.
Examples of carbon black include acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc. Examples of graphite include natural graphite and artificial graphite.
Examples of carbon nanotubes include single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes.
Examples of carbon fibers include pitch-based carbon fibers, PAN-based carbon fibers, and vapor grown carbon fibers (VGCF (registered trademark)).
As the conductive carbon material, carbon black is preferred.
The conductive carbon material may be used alone or in combination of two or more.

When a particulate material such as carbon black or graphite is used as the conductive carbon material, the average primary particle size of the conductive carbon material is preferably 50 nm or less, more preferably 40 nm or less, and even more preferably 30 nm or less. The average primary particle size of the conductive carbon material may be 10 nm or more.
In the present disclosure, the average primary particle size refers to the average value of the diameters of approximately several thousand primary particles.

When a particulate material such as carbon black or graphite is used as the conductive carbon material, the average particle size of the conductive carbon material is preferably 0.3 μm to 3 μm, more preferably 0.3 μm to 2 μm, even more preferably 0.5 μm to 1.5 μm, and particularly preferably 0.8 μm to 1.0 μm.
The average particle size of the conductive carbon material refers to the particle size at which the number ratio of particles, starting from the smallest particle size, accounts for 50% in a number particle size distribution obtained by measuring the particle size distribution of a conductive carbon material dispersion for an energy device based on a dynamic light scattering method (photon correlation method). An example of a measuring device based on the dynamic light scattering method (photon correlation method) is a Zeta-potential & Particlesize Analyzer, ELSZ (Otsuka Electronics Co., Ltd.).
When a fibrous material such as carbon nanotubes or carbon fibers is used as the conductive carbon material, the average length of the conductive carbon material is preferably 1 μm to 50 μm, more preferably 2 μm to 30 μm, and even more preferably 3 μm to 10 μm.
When a fibrous material such as carbon nanotubes or carbon fibers is used as the conductive carbon material, the average diameter of the conductive carbon material is preferably 1 nm to 500 nm, more preferably 5 nm to 400 nm, and even more preferably 10 nm to 300 nm.
The average length of the conductive carbon material can be determined by arbitrarily selecting 30 pieces of conductive carbon material, measuring the length of each, excluding the five largest and five smallest values, and averaging the 20 middle values. Note that, because the average length of carbon nanotubes, carbon fibers, etc. is short, at several tens of micrometers or less, the length of the conductive carbon material can be roughly approximated as a straight line. Therefore, the length of the conductive carbon material can be determined as the length of the line connecting both ends of the conductive carbon material.
The average diameter of the conductive carbon material can be analyzed from an electron microscope (SEM, TEM, etc.) photograph. For example, 30 pieces of conductive carbon material are selected at random, the diameter of each is measured, the five largest and five smallest values are omitted, and the average of the 20 middle values is taken as the average diameter. The diameter of the conductive carbon material refers to the maximum length in the direction perpendicular to the length direction of the conductive carbon material.

The content of the conductive carbon material contained in the dispersion liquid of the present disclosure is, for example, preferably 1% by mass to 50% by mass, more preferably 5% by mass to 25% by mass, and even more preferably 5% by mass to 15% by mass.

-Dispersant-
The dispersion of the present disclosure contains the dispersant of the present disclosure. In one embodiment, the content of the dispersant of the present disclosure contained in the dispersion of the present disclosure is, for example, preferably 0.1% by mass to 20% by mass, more preferably 0.5% by mass to 15% by mass, and even more preferably 1% by mass to 10% by mass. In another embodiment, the content is preferably 0.1% by mass to 10% by mass, more preferably 0.2% by mass to 8% by mass, and even more preferably 0.3% by mass to 6% by mass.

-solvent-
The solvent contained in the dispersion liquid of the present disclosure is not particularly limited as long as it can disperse the conductive carbon material.
As the solvent, from the viewpoint of the solubility of the dispersant, an amide solvent, a urea solvent, a lactone solvent, or a mixed solvent containing them is preferable, and N-methyl-2-pyrrolidone, γ-butyrolactone, or a mixed solvent containing them is more preferable. These solvents may be used alone or in combination of two or more.
Among these, the solvent preferably contains at least one of N-methyl-2-pyrrolidone and γ-butyrolactone.

- Viscosity of dispersion liquid -
The viscosity at 25°C of the dispersion of the present disclosure is preferably 500 mPa·s to 50,000 mPa·s, more preferably 1,000 mPa·s to 20,000 mPa·s, and even more preferably 2,000 mPa·s to 10,000 mPa·s.
In the present disclosure, viscosity is measured using a rotational shear viscometer at 25° C. and a shear rate of 1.0 s ⁻¹ .

- Preparation of dispersion -
The dispersion of the present disclosure can be prepared by mixing and stirring the conductive carbon material, the dispersant of the present disclosure, other components such as a leveling agent that are used as needed, and a solvent.
Examples of dispersing machines used for preparing the dispersion include a homomixer, a high-pressure homomixer, a disperser, a high-pressure homogenizer, a static mixer, a membrane emulsifier, Filmix (manufactured by Primix Corporation), an ultrasonic disperser, etc. Among these, Filmix is preferred.
It is more preferable to pre-mix the various components used in preparing the dispersion using a disperser such as a homomixer, and then use FILMICS to mix them. Using FILMICS allows the dispersion process to be completed in a short time. The conditions for stirring with FILMICS are not particularly limited, and can be carried out using a conventional method. For example, the conductive carbon material can be dispersed by stirring for 30 seconds at a peripheral speed of 30 m/s. The stirring time when stirring with FILMICS may be in the range of 30 seconds to 10 minutes.

<Composition for forming an energy device electrode and method for producing the same>
The composition for forming an energy device electrode of the present disclosure (hereinafter, sometimes referred to as the electrode-forming composition) contains a binder resin, an active material, a conductive carbon material, a dispersant for dispersing the conductive carbon material, and a solvent, and the dispersant contains the dispersant of the present disclosure.

The components constituting the electrode-forming composition of the present disclosure are described in detail below.

- Binder resin -
The electrode-forming composition of the present disclosure contains a binder resin. The type of binder resin is not particularly limited, and examples thereof include polyvinyl acetate, polymethyl methacrylate, nitrocellulose, fluororesin, and resins containing structural units derived from nitrile group-containing monomers.
Among these, at least one of a fluororesin and a resin containing a structural unit derived from a nitrile group-containing monomer is preferred.

There are no particular limitations on the fluororesin, so long as it is a resin containing, in the main chain, a structural unit in which some or all of the hydrogen atoms in the polyethylene skeleton are substituted with fluorine atoms.
Examples of fluororesins include homopolymers such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), and polychlorotrifluoroethylene (PCTFE), as well as copolymers such as tetrafluoroethylene-perfluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-ethylene copolymer (ETFE), and chlorotrifluoroethylene-ethylene copolymer, and modified products thereof modified with a carboxy group or the like. Among these, PVDF is preferred from the viewpoints of solubility in solvents, swelling in electrolyte solutions, resin flexibility, and the like. Furthermore, these fluororesins may be used alone or in combination of two or more.

The resin containing structural units derived from a nitrile group-containing monomer may be the specific nitrile resin described above. Resins containing structural units derived from a nitrile group-containing monomer may be used alone or in combination of two or more types.

The content of the binder resin in the solid content of the electrode-forming composition of the present disclosure is preferably 0.1% by mass to 10% by mass, more preferably 0.5% by mass to 5% by mass, and even more preferably 0.5% by mass to 3% by mass.
In the present disclosure, the term "solid content" refers to the components constituting the electrode-forming composition excluding the solvent.

-Active material-
The electrode-forming composition of the present disclosure may contain an active material. The active material used in the present disclosure is not particularly limited as long as it can reversibly insert and release lithium ions upon charging and discharging a lithium-ion secondary battery, which is an energy device. The positive electrode has the function of releasing lithium ions upon charging and receiving lithium ions upon discharging, while the negative electrode has the opposite function of receiving lithium ions upon charging and releasing lithium ions upon discharging. Therefore, different materials are usually used as the active materials for the positive electrode and the negative electrode, depending on the respective functions they possess.

The active material (negative electrode active material) used in the negative electrode of a lithium ion secondary battery can be a material capable of absorbing and releasing lithium ions and commonly used in the field of lithium ion secondary batteries. Examples of negative electrode active materials include metallic lithium, lithium alloys, intermetallic compounds, carbon materials, metal complexes, and organic polymer compounds. A single negative electrode active material may be used, or two or more may be used in combination. Among these, carbon materials are preferred. Examples of carbon materials include graphite such as natural graphite (e.g., flake graphite) and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; and carbon fiber. The average particle size of the carbon material is preferably 0.1 μm to 60 μm, more preferably 0.5 μm to 30 μm. The BET specific surface area of the carbon material is preferably 1 m ² /g to 10 m ² /g.
In the present disclosure, the average particle size of particles other than conductive carbon materials refers to the value (median diameter (D50)) at which the cumulative total from the small diameter side reaches 50% in a volume-based particle size distribution measured by dispersing a sample in purified water containing a surfactant and using a laser diffraction particle size distribution analyzer (e.g., SALD-3000J manufactured by Shimadzu Corporation).

Among carbon materials, graphite having a carbon hexagonal plane spacing (d ₀₀₂ ) of 3.35 Å to 3.40 Å in wide-angle X-ray diffraction and a crystallite c-axis direction (Lc) of 100 Å or more is particularly preferred from the viewpoint of further improving battery characteristics.
Among carbon materials, amorphous carbon in which the spacing between hexagonal carbon planes (d ₀₀₂ ) measured by wide-angle X-ray diffraction is 3.50 Å to 3.95 Å is particularly preferred from the viewpoint of further improving cycle characteristics and safety.

The BET specific surface area can be measured from the nitrogen adsorption capacity in accordance with, for example, JIS Z 8830:2013. As an evaluation device, for example, AUTOSORB-1 (trade name) manufactured by QUANTACHROME Co., Ltd. can be used. Since moisture adsorbed on the surface and in the structure of the sample is thought to affect the gas adsorption capacity, it is preferable to first perform a pretreatment by heating to remove moisture when measuring the BET specific surface area.
In the pretreatment, a measurement cell containing 0.05 g of a measurement sample is depressurized to 10 Pa or less using a vacuum pump, heated to 110°C, and held for 3 hours or more, and then naturally cooled to room temperature (25°C) while maintaining the depressurized state. After this pretreatment, measurements are performed at an evaluation temperature of 77 K and an evaluation pressure range of less than 1 in terms of relative pressure (equilibrium pressure relative to saturated vapor pressure).

On the other hand, the active material (cathode active material) used in the positive electrode of a lithium-ion secondary battery can be one commonly used in this field, such as lithium-containing metal composite oxides, olivine-type lithium salts, chalcogen compounds, and manganese dioxide. Lithium-containing metal composite oxides are metal oxides containing lithium and a transition metal, or metal oxides in which a portion of the transition metal in the metal oxide has been replaced with a different element. Examples of the different element include Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, V, and B, with Mn, Al, Co, Ni, and Mg being preferred. The different elements may be used alone or in combination of two or more.

Examples of lithium-containing metal composite oxides include Li _x CoO ₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _y Ni _1-y O ₂ , Li _x Co _y M ¹ _1-y O _z (in Li _x Co _y M ¹ _1-y O _z , M ¹ represents at least one element selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Cu, Zn, Al, Cr, Pb, Sb, V, and B), and Li _x Ni _1-y M ² _y O _z (in Li _x Ni _1-y M ² _y O _z , M ² represents at least one element selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Co, Cu, Zn, Al, Cr, Pb, Sb, V, and B.), Li _x Mn ₂ O ₄ , Li _x Mn _2-y M ³ _y O ₄ (in Li _x Mn _2-y M ³ _y O ₄ , M ³ represents at least one element selected from the group consisting of Na, Mg, Sc, Y, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, V, and B.) Here, x is in the range of 0<x≦1.2, y is in the range of 0 to 0.9, and z is in the range of 2.0 to 2.3. The x value, which indicates the molar ratio of lithium, increases or decreases with charge and discharge.
Examples of olivine-type lithium salts include _LiFePO4 . Examples of chalcogen compounds include titanium disulfide and _{molybdenum disulfide} . Other examples of positive electrode active materials include _Li2MPO4F (in _Li2MPO4F , M represents at least one element selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, V, and B). One type of positive electrode active material may be used alone, or two or more types may be used in combination.

The positive electrode active material preferably has an average particle size of 0.1 μm to 60 μm, more preferably 0.5 μm to 30 μm, and more preferably has a BET specific surface area of 1 m ² /g to 10 m ² /g.

-Conductive carbon materials-
The electrode-forming composition of the present disclosure contains a conductive carbon material. Specific examples of the conductive carbon material contained in the electrode-forming composition of the present disclosure are as described above.
The content of the conductive carbon material in the solid content of the electrode-forming composition of the present disclosure is preferably 0.1% by mass to 10% by mass, more preferably 0.5% by mass to 5% by mass, and even more preferably 1% by mass to 3% by mass.

-Dispersant-
The electrode-forming composition of the present disclosure contains a dispersant. The dispersant contained in the electrode-forming composition of the present disclosure includes the dispersant of the present disclosure. The electrode-forming composition of the present disclosure may contain a dispersant other than the dispersant of the present disclosure, as necessary.
Other dispersants include polyvinylpyrrolidone and polyvinyl alcohol.
The content of the dispersant in the solid content of the electrode-forming composition of the present disclosure is preferably 0.1% by mass to 10% by mass, more preferably 0.2% by mass to 5% by mass, and even more preferably 0.3% by mass to 3% by mass.
Furthermore, the content of the dispersant of the present disclosure in the dispersant contained in the electrode-forming composition of the present disclosure is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass.

-solvent-
The electrode-forming composition of the present disclosure contains a solvent. Examples of the solvent include water, amide-based solvents, urea-based solvents, lactone-based solvents, etc., or mixed solvents containing them. From the viewpoint of the solubility of the binder resin, etc., amide-based solvents, urea-based solvents, lactone-based solvents, etc., or mixed solvents containing them are preferred, and N-methyl-2-pyrrolidone, γ-butyrolactone, or mixed solvents containing them are more preferred. These solvents may be used alone or in combination of two or more.

There are no particular restrictions on the amount of solvent used, as long as it is at least the minimum amount necessary to keep the binder resin dissolved at room temperature (e.g., 25°C). In the slurry preparation process for producing electrodes for energy devices, viscosity is usually adjusted by adding solvent, so it is preferable to use an arbitrary amount that does not dilute the solution more than necessary.

-Other additives-
The electrode-forming composition of the present disclosure may also contain, as necessary, various additives such as a cross-linking component for complementing swelling resistance to the electrolyte, a rubber component for complementing the softness and flexibility of the electrode, an anti-settling agent for improving the electrode coatability of the slurry, an anti-foaming agent, a leveling agent, and the like.

-Physical properties of electrode-forming composition-
The electrode-forming composition of the present disclosure preferably has a viscosity at 25°C of 500 mPa·s to 50,000 mPa·s, more preferably 1,000 mPa·s to 20,000 mPa·s, and even more preferably 2,000 mPa·s to 10,000 mPa·s.

-Method for producing electrode-forming composition-
The method for producing the electrode-forming composition of the present disclosure is not particularly limited.
An example of a method for producing an electrode-forming composition according to the present disclosure may include a step of mixing an active material with the dispersion according to the present disclosure to prepare an active material dispersion, and a step of adding a binder resin to the active material dispersion.
In the step of preparing the active material dispersion, the active material, the dispersion of the present disclosure, and other components used as needed are mixed and stirred to prepare the active material dispersion.
Examples of devices used for mixing and stirring include planetary mixers, homomixers, high-pressure homomixers, dispersers, high-pressure homogenizers, static mixers, membrane emulsifiers, and ultrasonic dispersers.

In the step of adding the binder resin to the active material dispersion liquid, the binder resin added to the active material dispersion liquid is mixed by stirring to obtain the electrode-forming composition of the present disclosure. The stirring method is not particularly limited, and examples include stirring methods using the apparatus mentioned above in the step of preparing the active material dispersion liquid.

In the step of adding the binder resin to the active material dispersion, a powdered conductive carbon material may be further added to adjust the content of the conductive carbon material.
The method for producing an electrode-forming composition according to the present disclosure may also include a step of adding a conductive carbon material to the active material dispersion obtained in the step of preparing the active material dispersion.

When the electrode-forming composition of the present disclosure contains components other than the active material, binder resin, and conductive carbon material, the other components may be added in the process of preparing the active material dispersion liquid, in the process of adding the binder resin to the active material dispersion liquid, or in both processes.

<Energy device electrodes>
The energy device electrode of the present disclosure comprises a current collector and an electrode mixture layer provided on at least one surface of the current collector and formed using an energy device electrode-forming composition produced by the method for producing an energy device electrode-forming composition of the present disclosure.
The energy device electrode of the present disclosure can be used as an electrode for lithium ion secondary batteries, electric double layer capacitors, solar cells, fuel cells, and the like.
The following describes in detail the application of the energy device electrode of the present disclosure to an electrode of a lithium ion secondary battery, but the energy device electrode of the present disclosure is not limited to the following.

- Current collector -
The current collector used in the present disclosure is not particularly limited, and any current collector commonly used in the field of lithium ion secondary batteries can be used.
Examples of the current collector (positive electrode current collector) used in the positive electrode of a lithium ion secondary battery include sheets and foils containing stainless steel, aluminum, titanium, and the like.
Among these, a sheet or foil containing aluminum is preferred. The thickness of the sheet or foil is not particularly limited, and from the viewpoint of ensuring the strength and processability required as a current collector, it is, for example, preferably 1 μm to 500 μm, more preferably 2 μm to 80 μm, and even more preferably 5 μm to 50 μm.
Examples of the current collector (negative electrode current collector) used in the negative electrode of a lithium ion secondary battery include sheets and foils containing stainless steel, nickel, copper, and the like.
Among these, a copper-containing sheet or foil is preferred. The thickness of the sheet or foil is not particularly limited, and from the viewpoint of ensuring the strength and processability required as a current collector, it is, for example, preferably 1 μm to 500 μm, more preferably 2 μm to 100 μm, and even more preferably 5 μm to 50 μm.

- Electrode mixture layer -
The electrode mixture layer used in the lithium ion secondary battery can be formed using a composition for forming an energy device electrode that contains an active material, a solvent, and the like.
A positive electrode mixture layer is formed by using a composition for forming an energy device electrode containing a positive electrode active material, while a negative electrode mixture layer is formed by using a composition for forming an energy device electrode containing a negative electrode active material.

The electrode mixture layer can be formed by applying a slurry of the energy device electrode-forming composition produced by the method for producing an electrode-forming composition of the present disclosure onto at least one surface of a current collector, then drying to remove the solvent, and rolling as necessary.
The slurry can be applied using, for example, a comma coater etc. The application is suitably carried out so that the ratio of the positive electrode capacity to the negative electrode capacity (negative electrode capacity/positive electrode capacity) of the opposing electrodes is 1 or more.
The amount of the slurry to be applied is preferably 5 g/m ² to 500 g/m ² , more preferably 50 g/m ² to 300 g/m ² , in terms of dry mass per surface of the electrode mixture layer.
The solvent is removed by drying, for example, at 50° C. to 150° C., preferably 80° C. to 120° C., for 1 to 20 minutes, preferably 3 to 10 minutes.
The rolling is carried out using, for example, a roll press, and the mixture layer is pressed so that the density of the mixture layer for the negative electrode is, for example, 1 g/cm ³ to 2 g/cm ³ , preferably 1.2 g/cm ³ to 1.8 g/cm ³ , and the density of the mixture layer for the positive electrode is, for example, 2 g/cm ³ to 5 g/cm ³ , preferably 2 g/cm ³ to 4 g/cm ³ .
Furthermore, in order to remove residual solvent and adsorbed water in the electrode, the electrode may be dried in vacuum at 100° C. to 150° C. for 1 to 20 hours.

<Energy Devices>
The energy device of the present disclosure includes the energy device electrode of the present disclosure. Examples of the energy device of the present disclosure include a lithium ion secondary battery, an electric double layer capacitor, a solar cell, and a fuel cell.
Below, a detailed description will be given of the case where the energy device is a lithium ion secondary battery, but the energy device of the present disclosure is not limited to the following content.

A lithium ion secondary battery includes, for example, a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte solution.
The energy device electrode of the present disclosure is used as at least one of the positive electrode and the negative electrode. When an electrode other than the energy device electrode of the present disclosure is used as one of the positive electrode or the negative electrode, examples of the other electrode include those commonly used in the field of energy devices.

-Separator-
The separator is not particularly limited as long as it is ion-permeable while providing electronic insulation between the positive electrode and the negative electrode, and is resistant to oxidation on the positive electrode side and reduction on the negative electrode side. Materials (components) that satisfy these properties include resins, inorganic substances, and the like.

Examples of the resins that can be used include olefin polymers, fluorine polymers, cellulose polymers, polyimides, and nylons. Specifically, it is preferable to select a material that is stable against the electrolyte and has excellent liquid retention properties. It is preferable to use porous sheets or nonwoven fabrics made from polyolefins such as polyethylene and polypropylene.

Examples of inorganic materials that can be used include oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, sulfates such as barium sulfate and calcium sulfate, and glass. For example, a separator can be made by adhering the above inorganic materials in a fibrous or particulate form to a thin-film substrate such as a nonwoven fabric, a woven fabric, or a microporous film.
As the thin-film substrate, one with a pore size of 0.01 μm to 1 μm and a thickness of 5 μm to 50 μm is preferably used. Furthermore, for example, a composite porous layer formed by using the above-mentioned inorganic material in a fibrous or particulate form with a binder such as a resin can be used as a separator. Furthermore, this composite porous layer may be formed on the surface of a positive electrode or a negative electrode to form a separator. Alternatively, this composite porous layer may be formed on the surface of another separator to form a multilayer separator. For example, a composite porous layer formed by binding alumina particles with a 90% particle size (D90) of less than 1 μm with a fluororesin as a binder may be formed on the surface of a positive electrode.

-Electrolyte-
The electrolyte contains a solute (supporting salt), a non-aqueous solvent, and, if necessary, various additives. The solute is usually dissolved in the non-aqueous solvent. The electrolyte is impregnated into, for example, a separator.

As the solute, those commonly used in this field can be used, such as LiClO4, _LiBF4 , _LiPF6 , _LiAlCl4 , _LiSbF6 , _LiSCN , _LiCF3SO3 , _LiCF3CO2 , _{LiAsF6 , LiB10Cl10 ,} lower aliphatic lithium carboxylates, LiCl, _LiBr , _LiI , lithium chloroborane, borates, imide salts, etc. Examples of borate salts include lithium bis(1,2-benzenediolate(2-)-O,O')borate, lithium bis(2,3-naphthalenediolate(2-)-O,O')borate, lithium bis(2,2'-biphenyldiolate(2-)-O,O')borate, and lithium bis(5-fluoro-2-oleate-1-benzenesulfonic acid-O,O')borate. Examples of imide salts include lithium bistrifluoromethanesulfonyl imide ((CF ₃ SO ₂ ) ₂ NLi), lithium trifluoromethanesulfonyl nonafluorobutanesulfonyl imide ((CF ₃ SO ₂ )(C ₄ F ₉ SO ₂ )NLi), and lithium bispentafluoroethanesulfonyl imide ((C ₂ F ₅ SO ₂ ) ₂ NLi). The amount of the solute dissolved in the non-aqueous solvent is preferably 0.5 mol/L to 2 mol/L.

Non-aqueous solvents commonly used in this field can be used, including cyclic carbonates, chain carbonates, and cyclic carboxylic acid esters. Examples of cyclic carbonates include propylene carbonate (PC) and ethylene carbonate (EC). Examples of chain carbonates include diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC). Examples of cyclic carboxylic acid esters include gamma-butyrolactone (GBL) and gamma-valerolactone (GVL). One type of non-aqueous solvent may be used alone, or two or more types may be used in combination.

In addition, from the viewpoint of further improving battery characteristics, it is preferable that the non-aqueous solvent contains vinylene carbonate (VC).

When vinylene carbonate (VC) is contained, its content is preferably 0.1% to 2% by mass, and more preferably 0.2% to 1.5% by mass, based on the total amount of non-aqueous solvent.

Below, we describe an embodiment in which this disclosure is applied to a laminated lithium-ion secondary battery.

A laminated lithium-ion secondary battery can be fabricated, for example, as follows: First, the positive and negative electrodes are cut into square shapes, and tabs are welded to each electrode to create the positive and negative terminals. A separator is placed between the positive and negative electrodes to create an electrode laminate, which is then housed in an aluminum laminate pack. The positive and negative terminals are then removed from the aluminum laminate pack and sealed. Next, an electrolyte is poured into the aluminum laminate pack, and the opening of the aluminum laminate pack is sealed. This completes the lithium-ion secondary battery.

Next, with reference to the drawings, we will explain an embodiment in which the present disclosure is applied to an 18650 type cylindrical lithium ion secondary battery.

FIG. 1 shows a cross-sectional view of a lithium ion secondary battery to which the present disclosure is applied.
As shown in FIG. 1 , the lithium-ion secondary battery 1 of the present disclosure includes a bottomed, cylindrical battery container 6 made of nickel-plated steel. The battery container 6 houses an electrode group 5, which includes a strip-shaped positive electrode plate 2 and a strip-shaped negative electrode plate 3 wound in a spiral cross section with a separator 4 interposed therebetween. The separator 4 has a width of 58 mm and a thickness of 30 μm, for example. A ribbon-shaped aluminum positive electrode tab terminal extends from the upper end surface of the electrode group 5, one end of which is fixed to the positive electrode plate 2. The other end of the positive electrode tab terminal is joined by ultrasonic welding to the underside of a disk-shaped battery lid disposed above the electrode group 5 and serving as a positive electrode external terminal. Meanwhile, a ribbon-shaped copper negative electrode tab terminal extends from the lower end surface of the electrode group 5, one end of which is fixed to the negative electrode plate 3. The other end of the negative electrode tab terminal is joined by resistance welding to the inner bottom of the battery container 6. Thus, the positive electrode tab terminal and the negative electrode tab terminal are respectively extended to opposite ends of the electrode group 5. An insulating coating (not shown) is applied to the entire outer periphery of the electrode group 5. The battery lid is fixed to the top of the battery container 6 by crimping with an insulating resin gasket interposed therebetween. This seals the interior of the lithium-ion secondary battery 1. An electrolyte (not shown) is poured into the battery container 6.

The present disclosure will be explained in more detail below using examples, but the present invention is not limited to these examples.

Example 1
(Synthesis of specific nitrile resin)
397.2 g of purified water was added to a 0.5-liter separable flask equipped with a stirrer, thermometer, condenser, and nitrogen inlet tube, and the system was purged with nitrogen and heated to 73.0 °C. 347.0 mg of ammonium persulfate was dissolved in 2.5 g of purified water, and the entire amount was added to the system. Next, a mixture of 38.1 g of acrylonitrile (nitrile group-containing monomer, hereinafter sometimes referred to as AN) and 5.2 g of methoxypolyethylene glycol acrylate (monomer described in formula (I), manufactured by Shin-Nakamura Chemical Co., Ltd., AM-90G, hereinafter sometimes referred to as AM-90G) was added dropwise to the system over 2 hours, and the mixture was allowed to react for 1 hour. 420.0 mg of ammonium persulfate was dissolved in 7.8 g of purified water, and the entire amount was added to the system and allowed to react for 1 hour. Next, the temperature in the system was raised to 90.0 °C, and the reaction was allowed to continue for 1 hour. During the above process, the system was maintained under a nitrogen atmosphere, and stirring was continued at 250 rpm. After cooling to room temperature (25°C), the reaction solution was suction filtered, and the precipitated resin was filtered off. The filtered resin was washed with 1000.0 g of purified water. The washed resin was dried for 24 hours in a vacuum dryer set at 60°C and 150 Pa to obtain a specific nitrile resin. 423.0 g of N-methyl-2-pyrrolidone (hereinafter sometimes referred to as NMP) was added to a 0.5-liter separable flask equipped with a stirrer, thermometer, and condenser, and the temperature was raised to 100°C. 27.0 g of specific nitrile resin powder was then added, and the mixture was stirred at 300 rpm for 5 hours to obtain an NMP solution of the specific nitrile resin.

(Preparation of Conductive Carbon Material Dispersion for Energy Devices)
1.0 g of carbon black (Li-435, manufactured by Denka Company Limited, primary particle size 23 nm (catalog value); hereinafter, may be referred to as Li-435) and 8.3 g of an NMP solution of a specific nitrile resin were placed in a dedicated container of a disperser (FILMICS FM-30L, manufactured by Primix Corporation), and NMP was further added so that the solids concentration became 12.0 mass % (3.2 g in Example 1). After that, the mixture was stirred for 30 seconds at a peripheral speed of 30 m/s using the FILMICS FM-30L, thereby obtaining a conductive carbon material dispersion liquid 1 for an energy device.

Example 2
A conductive carbon material dispersion liquid 2 for an energy device was obtained in the same manner as in Example 1, except that the stirring time in the Filmix FM-30L was changed from 30 seconds to 1 minute.

Example 3
Conductive carbon material dispersion liquid 3 for energy devices was obtained in the same manner as in Example 1, except that the stirring time in the Filmix FM-30L was changed from 30 seconds to 3 minutes.

Example 4
Conductive carbon material dispersion liquid 4 for energy devices was obtained in the same manner as in Example 1, except that the stirring time in the Filmix FM-30L was changed from 30 seconds to 5 minutes.

Example 5
Conductive carbon material dispersion liquid 5 for energy devices was obtained in the same manner as in Example 1, except that the stirring time in the Filmix FM-30L was changed from 30 seconds to 10 minutes.

Example 6
Conductive carbon material dispersion liquid 6 for energy devices was obtained in the same manner as in Example 3, except that the amount of Li-435 was 1.0 g and the amount of the NMP solution of the specific nitrile resin was 2.3 g.

Example 7
Conductive carbon material dispersion liquid 7 for energy devices was obtained in the same manner as in Example 3, except that the amount of Li-435 was 1.0 g and the amount of the NMP solution of the specific nitrile resin was 6.5 g.

Example 8
Conductive carbon material dispersion liquid 8 for energy devices was obtained in the same manner as in Example 3, except that 0.8 g of Li-435 and 9.6 g of the NMP solution of the specific nitrile resin were used.

Example 9
Conductive carbon material dispersion liquid 9 for energy devices was obtained in the same manner as in Example 3, except that in the synthesis of the specific nitrile resin, the reaction temperature was changed from 73.0°C to 75.0°C.

Example 10
A conductive carbon material dispersion liquid 10 for an energy device was obtained in the same manner as in Example 3, except that in the synthesis of the specific nitrile resin, the reaction temperature was changed from 73.0°C to 76.0°C.

Example 11
Conductive carbon material dispersion liquid 11 for energy devices was obtained in the same manner as in Example 3, except that in the synthesis of the specific nitrile resin, the monomers were changed to a mixture of 37.2 g of AN and 6.1 g of AM-90G.

Example 12
A conductive carbon material dispersion liquid 12 for energy devices was obtained in the same manner as in Example 3, except that in the synthesis of the specific nitrile resin, the monomers were changed to a mixture of 39.0 g of AN and 4.3 g of AM-90G.

Example 13
Conductive carbon material dispersion liquid 13 for energy devices was obtained in the same manner as in Example 3, except that in the synthesis of the specific nitrile resin, the monomers were changed to a mixture of 39.8 g of AN and 3.5 g of AM-90G.

Example 14
Conductive carbon material dispersion liquid 14 for energy devices was obtained in the same manner as in Example 3, except that in the synthesis of the specific nitrile resin, the monomers were changed to a mixture of 40.7 g of AN and 2.6 g of AM-90G.

Example 15
Conductive carbon material dispersion liquid 15 for energy devices was obtained in the same manner as in Example 3, except that in the synthesis of the specific nitrile resin, the monomer was changed to a mixture of 42.0 g of AN and 1.3 g of AM-90G.

Example 16
Conductive carbon material dispersion liquid 16 for energy devices was obtained in the same manner as in Example 3, except that in the synthesis of the specific nitrile resin, the monomer was changed to 43.3 g of AN.

<Example 16-2>
A conductive carbon material dispersion liquid 16-2 for energy devices was obtained in the same manner as in Example 3, except that the amount of Li-435 was 1.0 g and the amount of the NMP solution of the specific nitrile resin was 5.1 g.

<Example 16-3>
A conductive carbon material dispersion liquid 16-3 for energy devices was obtained in the same manner as in Example 3, except that 0.8 g of Li-435 and 8.0 g of the NMP solution of the specific nitrile resin were used.

<Example 16-4>
A conductive carbon material dispersion liquid 16-4 for an energy device was obtained in the same manner as in Example 3, except that 0.7 g of Li-435 and 9.2 g of the NMP solution of the specific nitrile resin were used.

<Example 16-5>
A conductive carbon material dispersion liquid 16-5 for an energy device was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.0 g of carbon black (Li-100, manufactured by Denka Company Limited, primary particle size 35 nm (catalog value); hereinafter, may be referred to as Li-100) and 1.2 g of the NMP solution of the specific nitrile resin was used.

<Example 16-6>
A conductive carbon material dispersion liquid 16-6 for energy devices was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.0 g of Li-100 and the NMP solution of the specific nitrile resin was 2.4 g.

<Example 16-7>
A conductive carbon material dispersion liquid 16-7 for energy devices was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.0 g of Li-100 and the NMP solution of the specific nitrile resin was 5.1 g.

<Example 16-8>
A conductive carbon material dispersion liquid 16-8 for energy devices was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.0 g of Li-100 and the NMP solution of the specific nitrile resin was 6.6 g.

<Example 16-9>
A conductive carbon material dispersion liquid 16-9 for an energy device was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.5 g of carbon black (Li-400, manufactured by Denka Company Limited, primary particle size 48 nm (catalog value); hereinafter, may be referred to as Li-400) and 0.9 g of the NMP solution of the specific nitrile resin was used.

<Example 16-10>
A conductive carbon material dispersion liquid 16-10 for energy devices was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.0 g of Li-400 and 1.2 g of the NMP solution of the specific nitrile resin was used.

<Example 16-11>
A conductive carbon material dispersion liquid 16-11 for energy devices was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.0 g of Li-400 and the NMP solution of the specific nitrile resin was 2.4 g.

<Example 16-12>
A conductive carbon material dispersion liquid 16-12 for energy devices was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.0 g of Li-400 and the NMP solution of the specific nitrile resin was 5.1 g.

<Examples 16-13>
A conductive carbon material dispersion liquid 16-13 for energy devices was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.0 g of Li-400 and the NMP solution of the specific nitrile resin was 6.6 g.

<Examples 16-14>
A conductive carbon material dispersion liquid 16-14 for an energy device was obtained in the same manner as in Example 3, except that Li-435 was replaced with 1.5 g of vapor-grown carbon fiber (Showa Denko K.K., VGCF-H, average length 6 μm, average diameter 150 nm, hereinafter may be referred to as VGCF-H) and 0.9 g of an NMP solution of a specific nitrile resin.

<Examples 16-15>
A conductive carbon material dispersion 16-15 for energy devices was obtained in the same manner as in Example 3, except that 1.0 g of VGCF-H was used instead of Li-435 and 1.2 g of the NMP solution of the specific nitrile resin was used.

<Example 16-16>
A conductive carbon material dispersion 16-16 for an energy device was obtained in the same manner as in Example 3, except that 1.0 g of VGCF-H was used instead of Li-435 and 2.4 g of the NMP solution of the specific nitrile resin was used.

<Comparative Example 1>
A conductive carbon material dispersion liquid C1 for an energy device was obtained in the same manner as in Example 1, except that polyvinylidene fluoride (PVDF) was used instead of the specific nitrile resin.

<Comparative Example 2>
A conductive carbon material dispersion C2 for an energy device was obtained in the same manner as in Example 2, except that polyvinylidene fluoride (PVDF) was used instead of the specific nitrile resin.

<Comparative Example 3>
A conductive carbon material dispersion C3 for an energy device was obtained in the same manner as in Example 3, except that polyvinylidene fluoride (PVDF) was used instead of the specific nitrile resin.

<Comparative Example 4>
A conductive carbon material dispersion C4 for an energy device was obtained in the same manner as in Example 4, except that polyvinylidene fluoride (PVDF) was used instead of the specific nitrile resin.

Comparative Example 5
A conductive carbon material dispersion C5 for an energy device was obtained in the same manner as in Example 5, except that polyvinylidene fluoride (PVDF) was used instead of the specific nitrile resin.

<Comparative Example 5-2>
A conductive carbon material dispersion liquid C5-2 for an energy device was obtained in the same manner as in Example 3, except that polyvinylidene fluoride (PVDF) was used instead of the specific nitrile resin and Li-100 was used instead of Li-435.

<Comparative Example 5-3>
A conductive carbon material dispersion liquid C5-3 for an energy device was obtained in the same manner as in Example 3, except that polyvinylidene fluoride (PVDF) was used instead of the specific nitrile resin and Li-400 was used instead of Li-435.

<Comparative Example 5-4>
A conductive carbon material dispersion C5-4 for energy devices was obtained in the same manner as in Example 3, except that polyvinylidene fluoride (PVDF) was used instead of the specific nitrile resin and VGCF-H was used instead of Li-435.

(Measurement of weight average molecular weight of specific nitrile resin)
The specific nitrile resin used in Examples 1 to 16, etc., was diluted with NMP to a concentration of 0.1% by mass, and insoluble matter was removed by passing it through a PTFE (polytetrafluoroethylene) filter [Kurashiki Boseki Co., Ltd., HPLC (high performance liquid chromatography) pretreatment, Chromatodisc, model number: 13N, pore size: 0.45 μm]. The weight average molecular weight was measured using GPC [pump: L6200 Pump (Hitachi, Ltd.), detector: differential refractive index detector L3300 RI Monitor (Hitachi, Ltd.), column: TSKgel-G5000HXL and TSKgel-G2000HXL (total of two) (both manufactured by Tosoh Corporation) connected in series, column temperature: 30 ° C, eluent: N-methyl-2-pyrrolidone, flow rate: 1.0 mL / min, standard substance: polystyrene]. The results are shown in Tables 1 to 3.

(Evaluation of dispersibility of conductive carbon material dispersion for energy devices)
The dispersibility of the conductive carbon material dispersions for energy devices described in Examples 1 to 16, Examples 16-2 to 16-16, Comparative Examples 1 to 5, and Comparative Examples 5-2 to 5-4 was evaluated based on appearance observation and dispersed particle size. The conductive carbon material dispersions for energy devices were diluted with NMP so that the carbon black concentration or VGCF-H concentration in the dispersions became 1.0 mass%. The diluted solutions were visually observed to confirm the presence or absence of aggregates. For those dispersions in which no aggregates were visually observed, the dispersed particle size was evaluated.
For examples and comparative examples using carbon black Li-435, Li-100, or Li-400 as the conductive carbon material, the prepared dispersion was added to a glass cell attached to a particle size distribution measuring instrument (Otsuka Electronics Co., Ltd., Zeta-potential & Particlesize Analyzer, ELSZ) to make up approximately 80% of the glass volume, and the cell was set in the measuring section of the particle size distribution measuring instrument, and measurements were carried out 70 times in total. In the obtained number particle size distribution, the particle size (D50) at which the number ratio reached 50% when integrating the smallest particle size was determined. This particle size (D50) corresponds to the dispersed particle size of the carbon black. Dispersibility was evaluated using visual observation of appearance and dispersed particle size according to the following criteria. A indicates the most excellent dispersibility, and D indicates the poorest dispersibility.
A: Particle size (D50) less than 1.0 μm B: Particle size (D50) 1.0 μm or more but less than 3.0 μm C: Particle size (D50) 3.0 μm or more D: Visually observed aggregates For the Examples and Comparative Examples using VGCF-H as the conductive carbon material, the dispersed particle size was determined in the same manner as for carbon black, and dispersibility was evaluated using visual appearance observation and dispersed particle size according to the following criteria. A indicates the best dispersibility, and C indicates the worst dispersibility.
A: Particle size (D50) is less than 7.0 μm B: Particle size (D50) is 7.0 μm or more and less than 10.0 μm C: Aggregates are visible

It can be seen that Examples 1 to 16 and 16-2 to 16-13, which contain the specific nitrile resin, have superior dispersibility of carbon black, a conductive carbon material, compared to Comparative Examples 1 to 5, 5-2, and 5-3, which contain PVDF, a resin that does not contain a structural unit derived from a nitrile group-containing monomer. Although Examples 3 and 11 to 16 vary the amount of the monomer represented by formula (I), good dispersibility of the conductive carbon material was obtained in all cases, suggesting that the improved dispersibility of the conductive carbon material is due to the effect of the structural unit derived from the nitrile group-containing monomer.
It can be seen that Examples 16-14 to 16-16, which used VGCF-H as the conductive carbon material, had superior dispersibility of VGCF-H compared to Comparative Example 5-4, which contained PVDF, a resin that does not contain structural units derived from a nitrile group-containing monomer. This shows that the specific nitrile resin is effective not only for dispersing carbon black but also for dispersing vapor-grown carbon fiber.

Example 17
(Preparation of Composition for Forming Energy Device Electrodes (Energy Device Electrode Slurry))
An electrode slurry for an energy device was obtained by mixing a positive electrode active material (MX6 manufactured by Umicore Japan K.K., hereinafter sometimes referred to as NMC) and the conductive carbon material dispersion 3 for an energy device obtained in Example 3, and then adding and mixing the NMP solution of PVDF and NMP for viscosity adjustment. The solid content ratio in the electrode slurry for an energy device (positive electrode active material: conductive carbon material: specific nitrile resin: PVDF) was 96% by mass:2% by mass:1% by mass:1% by mass.

(Fabrication of energy device electrodes)
The obtained electrode slurry for an energy device was evenly and homogeneously applied to one side of an aluminum foil (current collector) having a thickness of 15 μm so that the coating amount after drying was 230 g/ ^m2 . Thereafter, a drying treatment was carried out and the coating was rolled by pressing to a density of 3.3 g/ ^cm3 to obtain an energy device electrode.

(Fabrication of energy devices)
An energy device electrode cut into a 1.50 cm diameter circle and a 20 μm thick polyethylene microporous membrane separator cut into a 1.80 cm diameter circle were stacked in this order on a 2.00 cm diameter stainless steel coin outer container, and several drops of electrolyte (a 1.20 M _LiPF6 -containing mixed solution of ethylene carbonate/ethyl methyl carbonate/dimethyl carbonate = 2/2/3 (volume ratio) + 0.80 mass% vinylene carbonate) were dripped onto the container until it did not overflow. Furthermore, a 1.60 cm diameter circle of metallic lithium and a 200 μm thick stainless steel plate cut into a 1.60 cm diameter circle as a spacer were stacked in this order, and a stainless steel cap was placed over the container via a polypropylene packing. The container was then sealed using a crimping machine for coin battery production to produce an energy device for evaluation.

Example 18
An energy device for evaluation was produced in the same manner as in Example 17, except that the conductive carbon material dispersion liquid 6 for an energy device obtained in Example 6 was used and the solid content ratio (positive electrode active material: conductive carbon material: specific nitrile resin: PVDF) in the electrode slurry for an energy device was changed to 96 mass %: 2 mass %: 0.3 mass %: 1.7 mass %.

Example 19
An energy device for evaluation was produced in the same manner as in Example 17, except that the conductive carbon material dispersion liquid 7 for an energy device obtained in Example 7 was used and the solid content ratio (positive electrode active material: conductive carbon material: specific nitrile resin: PVDF) in the electrode slurry for an energy device was changed to 96 mass %: 2 mass %: 0.8 mass %: 1.2 mass %.

Example 20
An energy device for evaluation was produced in the same manner as in Example 17, except that the conductive carbon material dispersion liquid 8 for an energy device obtained in Example 8 was used and the solid content ratio (positive electrode active material: conductive carbon material: specific nitrile resin: PVDF) in the electrode slurry for an energy device was changed to 96 mass %: 2 mass %: 1.4 mass %: 0.6 mass %.

Example 21
An energy device for evaluation was produced in the same manner as in Example 18, except that the conductive carbon material dispersion liquid 11 for an energy device obtained in Example 11 was used.

Example 22
An energy device for evaluation was produced in the same manner as in Example 18, except that the conductive carbon material dispersion liquid 12 for an energy device obtained in Example 12 was used.

Example 23
An energy device for evaluation was produced in the same manner as in Example 18, except that the conductive carbon material dispersion liquid 13 for an energy device obtained in Example 13 was used.

Example 24
An energy device for evaluation was produced in the same manner as in Example 18, except that the conductive carbon material dispersion liquid 14 for an energy device obtained in Example 14 was used.

Example 25
An energy device for evaluation was produced in the same manner as in Example 18, except that the conductive carbon material dispersion liquid 15 for an energy device obtained in Example 15 was used.

Example 26
An energy device for evaluation was produced in the same manner as in Example 18, except that the conductive carbon material dispersion liquid 16 for an energy device obtained in Example 16 was used.

<Comparative Example 6>
An energy device for evaluation was produced in the same manner as in Example 17, except that the conductive carbon material dispersion liquid C1 for an energy device obtained in Comparative Example 1 was used and the solid content ratio (positive electrode active material: conductive carbon material: PVDF) in the electrode slurry for an energy device was changed to 96 mass %:2 mass %:2 mass %.

Comparative Example 7
An energy device for evaluation was produced in the same manner as in Comparative Example 6, except that the conductive carbon material dispersion liquid C2 for an energy device obtained in Comparative Example 2 was used.

<Comparative Example 8>
An energy device for evaluation was produced in the same manner as in Comparative Example 6, except that the conductive carbon material dispersion C3 for an energy device obtained in Comparative Example 3 was used.

<Comparative Example 9>
An energy device for evaluation was produced in the same manner as in Comparative Example 6, except that the conductive carbon material dispersion liquid C4 for an energy device obtained in Comparative Example 4 was used.

<Comparative Example 10>
An energy device for evaluation was produced in the same manner as in Comparative Example 6, except that the conductive carbon material dispersion liquid C5 for an energy device obtained in Comparative Example 5 was used.

(Initialization of the evaluation energy device)
The fabricated energy device for evaluation was placed in a thermostatic chamber at 25.0°C and connected to a charge/discharge device (Toyo Systems Co., Ltd., TOSCAT-3200). After constant current charging at 0.10 C to 4.2 V, it was charged at a constant voltage at 4.2 V until the current value reached 0.01 C. It was then discharged at a constant current of 0.10 C to 2.7 V. This charge/discharge cycle was repeated three times to initialize the energy device for evaluation. The unit "C" means "current value (A)/battery capacity (Ah)".

(Evaluation of output characteristics)
The initialized energy device for evaluation was placed in a thermostatic chamber at 25.0°C and connected to a charge/discharge device (Toyo Systems Co., Ltd., TOSCAT-3200), and then charged/discharged in the following order (1) to (5).
(1) The battery was charged at a constant current of 0.20 C up to 4.2 V, and then charged at a constant voltage of 4.2 V down to a current of 0.01 C. The battery was discharged at a constant current of 0.20 C down to 2.7 V, and the discharge capacity was measured.
(2) The battery was charged at a constant current of 0.20 C up to 4.2 V, and then charged at a constant voltage of 4.2 V down to a current of 0.01 C. The battery was discharged at a constant current of 0.33 C down to 2.7 V, and the discharge capacity was measured.
(3) The battery was charged at a constant current of 0.20 C up to 4.2 V, and then charged at a constant voltage of 4.2 V down to a current of 0.01 C. The battery was discharged at a constant current of 0.50 C down to 2.7 V, and the discharge capacity was measured.
(4) The battery was charged at a constant current of 0.20 C up to 4.2 V, and then charged at a constant voltage of 4.2 V down to a current of 0.01 C. The battery was discharged at a constant current of 1.00 C down to 2.7 V, and the discharge capacity was measured.
(5) The battery was charged at a constant current of 0.20 C up to 4.2 V, and then charged at a constant voltage of 4.2 V down to a current of 0.01 C. The battery was discharged at a constant current of 3.00 C down to 2.7 V, and the discharge capacity was measured.

The discharge capacity at 0.20 C and the discharge capacity at 3.00 C were used to calculate the retention rate using the following formula, and the output characteristics were evaluated according to the following criteria. A indicates the best output characteristics, and D indicates the worst output characteristics. The results are shown in Table 5.
Maintenance rate = discharge capacity at 3.00C x 100/discharge capacity at 0.20C A: 85% or more B: 80% or more but less than 85% C: 75% or more but less than 80% D: less than 75%

(Evaluation of DC resistance)
The DC resistance was evaluated using the results of evaluating the output characteristics of the energy device for evaluation.
The horizontal axis was plotted with the current values during discharge (1) to (5) above, and the vertical axis was plotted with the voltage difference between before discharge and 5 seconds after the start of discharge, and the DC resistance was calculated from the slope.

(Evaluation of cycle characteristics)
The energy device whose output characteristics were evaluated was placed in a thermostatic chamber at 25.0°C and connected to a charge/discharge device (Toyo Systems Co., Ltd., TOSCAT-3200). It was charged at a constant current of 0.10 C to 4.2 V, and then charged at a constant voltage of 4.2 V until the current value reached 0.01 C. It was discharged at a constant current of 0.10 C to 2.7 V, and the discharge capacity was measured. This charge/discharge cycle was repeated 20 times. The DC resistance of the evaluation energy device after 20 charge/discharge cycles was calculated using the method described above, and the DCR increase rate was calculated using the formula below. The cycle characteristics were evaluated according to the following criteria. A indicates the best cycle characteristics, and C indicates the worst cycle characteristics. The results are shown in Table 2.
DCR increase rate = DC resistance before repeated charge/discharge × 100 / DC resistance after repeated charge/discharge A: Less than 180% B: 180% or more, but less than 190% C: 190% or more

The disclosure of International Application PCT/JP2020/008361, filed February 28, 2020, is incorporated herein by reference in its entirety.
All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims (13)

The composition contains a resin containing a structural unit derived from a nitrile group-containing monomer and a structural unit derived from a monomer represented by the following formula (I):
The conductive carbon material dispersant for energy devices, wherein the mass ratio of the structural units derived from the nitrile group-containing monomer in the resin is more than 80 mass % and 100 mass % or less .

[In formula (I), R ₁ represents a hydrogen atom or a methyl group, R ₂ represents a hydrogen atom or a monovalent hydrocarbon group, and n represents an integer of 2 to 30.] The conductive carbon material dispersant for energy devices according to claim 1 , wherein the structural unit derived from the nitrile group-containing monomer is contained in the main chain of the resin. A conductive carbon material dispersion for an energy device, comprising: a conductive carbon material; the conductive carbon material dispersant for an energy device according to claim 1; and a solvent. 4. The conductive carbon material dispersion for an energy device according to claim 3 , wherein the conductive carbon material has an average primary particle size of 50 nm or less. The conductive carbon material dispersion for an energy device according to claim 3 or 4 , wherein the conductive carbon material contains carbon black. 6. The conductive carbon material dispersion for an energy device according to claim 3 , wherein the conductive carbon material has an average particle size of 0.3 μm to 3 μm. The conductive carbon material dispersion for an energy device according to claim 3 , wherein the conductive carbon material contains carbon fibers. The conductive carbon material dispersion for an energy device according to any one of claims 3 to 7 , wherein the solvent contains at least one of N-methyl-2-pyrrolidone and γ-butyrolactone. 3. A composition for forming an energy device electrode, comprising: a binder resin; an active material; a conductive carbon material; a dispersant for dispersing the conductive carbon material; and a solvent, wherein the dispersant includes the conductive carbon material dispersant for an energy device according to claim 1 or 2 . A method for producing a composition for forming an energy device electrode, comprising: a step of mixing an active material with the conductive carbon material dispersion for an energy device according to any one of claims 3 to 8 to prepare an active material dispersion; and a step of adding a binder resin to the active material dispersion. The method for producing a composition for forming an energy device electrode according to claim 10 , further comprising the step of adding a conductive carbon material to the active material dispersion liquid. A current collector;
an electrode mixture layer provided on at least one surface of the current collector and formed using a composition for forming an energy device electrode produced by the method for producing a composition for forming an energy device electrode according to claim 10 or 11 ; and
An energy device electrode having: An energy device comprising the energy device electrode according to claim 12 .