Composition for dispersing conductive material for electrochemical element, conductive material dispersion liquid for electrochemical element, slurry composition for electrochemical element electrode, electrode for electrochemical element, and electrochemical element

Abstract

A composition for dispersing a conductive material for an electrochemical element, including a polymer A and a compound A that has two or more functional groups selected from the group consisting of a cyano group, a carboxyl group, and a phenyl group.

Description

Conductive material dispersion composition for electrochemical elements, conductive material dispersion liquid for electrochemical elements, slurry composition for electrochemical element electrodes, electrodes for electrochemical elements, and electrochemical elements

[0001] The present invention relates to a conductive material dispersion composition for electrochemical devices, a conductive material dispersion liquid for electrochemical devices, a slurry composition for electrochemical device electrodes, an electrode for electrochemical devices, and an electrochemical device.

[0002] Electrochemical devices such as nonaqueous secondary batteries (e.g., lithium ion secondary batteries) are small, lightweight, have high energy density, and can be repeatedly charged and discharged, and are therefore used in a wide range of applications. Therefore, in recent years, improvements to battery components such as electrodes have been investigated with the aim of further improving the performance of electrochemical devices.

[0003] In order to improve the performance of electrochemical devices, various improvements have been made to the materials that form the electrodes for electrochemical devices. Electrodes for electrochemical devices have a structure in which an electrode mixture layer, which is mainly composed of an electrode active material and, as necessary, contains other components such as a conductive additive and a binder to impart specific functions such as conductivity, adhesion, and flexibility to the electrode, is disposed on an electrode substrate.

[0004] As a method for forming an electrode mixture layer, a method has been studied in the past in which a slurry composition containing an electrode active material, a conductive carbon material, a polymer, and a solvent is applied to an electrode substrate and dried to form an electrode mixture layer.

[0005] Various attempts have been made to improve the polymers that can be used in the above-mentioned ways in order to impart excellent performance to electrochemical devices.

[0006] Specifically, for example, Patent Document 1 proposes blending two types of hydrogenated nitrile copolymers, each having a weight-average molecular weight within a predetermined range, as a dispersant for carbon nanotubes. Furthermore, for example, Patent Document 2 discloses a carbon nanotube dispersion containing a primary dispersant that is a hydrogenated nitrile copolymer and an auxiliary dispersant that is a copolymer containing an oxyalkylene unit and at least one of a styrene unit and an alkylene unit. Furthermore, for example, Patent Document 3 discloses a conductive material paste for electrochemical elements that contains a predetermined imidazole compound.

[0007] Korean Patent Publication No. 10-2023-0022000 International Publication No. 2023 / 008949 International Publication No. 2019 / 107463

[0008] However, the various polymers or compounds disclosed in the above-mentioned prior art have room for further improvement in terms of increasing the dispersibility of conductive materials for electrochemical elements when used to disperse conductive materials for electrochemical elements.

[0009] Therefore, an object of the present invention is to provide a conductive material dispersion composition for electrochemical elements that can improve the dispersibility of conductive materials for electrochemical elements. Another object of the present invention is to provide a conductive material dispersion liquid for electrochemical elements that has excellent dispersibility. A further object of the present invention is to provide a slurry composition for electrochemical element electrodes that includes the above-mentioned conductive material dispersion composition for electrochemical elements. And an object of the present invention is to provide an electrode for electrochemical elements formed using the above-mentioned slurry composition for electrochemical element electrodes, and an electrochemical element including such an electrode.

[0010] The present inventors have conducted extensive research to solve the above problems, and have newly discovered that a composition containing a compound A having two or more specific functional groups and a polymer can act to enhance the dispersibility of a conductive material for an electrochemical element, thereby completing the present invention.

[0011] That is, the object of the present invention is to advantageously solve the above-mentioned problems, and the present invention provides a conductive material dispersion composition for electrochemical elements as set forth in the following [1] to

[13] , a conductive material dispersion liquid for electrochemical elements as set forth in the following

[14] to

[15] , a slurry for electrochemical element electrodes as set forth in the following

[16] , an electrode for electrochemical elements as set forth in the following

[17] , and an electrochemical element as set forth in the following

[18] .

[0012] [1] A composition for dispersing a conductive material for electrochemical elements, comprising a compound A having two or more functional groups and a polymer A, wherein the compound A having two or more functional groups has two or more functional groups selected from the group consisting of a cyano group, a carboxyl group, and a phenyl group, and the two or more functional groups may be the same or different. Thus, the composition comprising the compound A having two or more functional groups selected from the group consisting of a cyano group, a carboxyl group, and a phenyl group and the polymer A can act to enhance the dispersibility of the conductive material for electrochemical elements.

[0013] [2] In the composition for dispersing a conductive material for electrochemical elements according to [1] above, it is preferable that the polymer A contains a linear alkylene structural unit having 4 or more carbon atoms and a nitrile-containing monomer unit. If the polymer A contains a linear alkylene structural unit having 4 or more carbon atoms and a nitrile-containing monomer unit, the dispersibility of the conductive material for electrochemical elements can be further improved. In the present invention, the phrase "containing a monomer unit" in the polymer A means that "the polymer A obtained using the monomer contains a repeating unit derived from the monomer." In addition, in the present invention, the content ratio of the monomer unit in the polymer A is １ H-NMR and １３ It can be measured using a nuclear magnetic resonance (NMR) method such as C-NMR.

[0014] [3] In the composition for dispersing a conductive material for electrochemical elements according to the above [1] or [2], the molecular weight of the compound A having two or more functional groups is preferably from 70 to 4000. If the molecular weight of the compound A is from 70 to 4000, the dispersibility of the conductive material for electrochemical elements can be further improved.

[0015] [4] In the conductive material dispersion composition for electrochemical elements according to the above [1] or [2], the molecular weight of the compound A having two or more functional groups is preferably 70 or more and 8,000 or less.

[0016] [5] In the conductive material dispersion composition for electrochemical elements according to the above [1] or [2], the molecular weight of the compound A having two or more functional groups is preferably 85 or more and 8,000 or less.

[0017] [6] In the conductive material dispersion composition for electrochemical elements according to the above [1] or [2], the compound A having two or more functional groups preferably has a molecular weight of 85 or more and 4,000 or less.

[0018] [7] In the conductive material dispersion composition for electrochemical elements according to the above [1] or [2], the molecular weight of the compound A having two or more functional groups is preferably 85 or more and 3,000 or less.

[0019] [8] In the electroconductive material dispersion composition for electrochemical elements according to any one of [1] to [7] above, the weight-average molecular weight of the polymer A is preferably 3,000 or more and 500,000 or less. Thus, if the weight-average molecular weight of the polymer A is 3,000 or more and 500,000 or less, the dispersibility of the electroconductive material for electrochemical elements can be further improved. The weight-average molecular weight of the polymer A can be measured according to the method described in the Examples of this specification.

[0020] [9] In the conductive material dispersion composition for electrochemical elements according to any one of the above [1] to [7], the weight average molecular weight of the polymer A is preferably 8,000 or more and 400,000 or less.

[0021]

[10] In the conductive material dispersion composition for electrochemical elements according to any one of the above [1] to [7], the weight average molecular weight of the polymer A is preferably 15,000 or more and 300,000 or less.

[0022]

[11] In the electroconductive material dispersion composition for electrochemical elements according to any one of [1] to

[10] above, the blending ratio of the compound A is preferably in the range of 10 parts by mass to 50 parts by mass, where the total mass of the polymer A and the compound A having two or more functional groups is 100 parts by mass. When the mass ratio between the polymer A and the compound A having two or more functional groups is within the above range, the dispersibility of the electroconductive material for electrochemical elements can be further improved.

[0023]

[12] In the conductive material dispersion composition for electrochemical elements according to any one of the above [1] to

[10] , the blending ratio of the compound A is preferably in the range of 18 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the total mass of the polymer A and the compound A having two or more functional groups.

[0024]

[13] In the conductive material dispersion composition for electrochemical elements according to any one of the above [1] to

[10] , it is preferable that the blending ratio of the compound A is in the range of 18 parts by mass or more and 32 parts by mass or less, where the total mass of the polymer A and the compound A having two or more functional groups is 100 parts by mass.

[0025]

[14] A conductive material dispersion for electrochemical elements, comprising a conductive carbon material as a conductive material, a solvent, and the conductive material dispersion composition for electrochemical elements according to any one of [1] to

[13] above. Such a conductive material dispersion for electrochemical elements has excellent dispersibility.

[0026]

[15] In the conductive material dispersion for electrochemical elements according to the above

[14] , the conductive carbon material has a BET specific surface area of ​​150 m ２ / g or more, and the G / D ratio determined by Raman spectroscopy may be 0.4 or more. The specific surface area and G / D ratio of the conductive carbon material can be measured by the method described in the Examples of this specification. In this specification, the "BET specific surface area" refers to the nitrogen adsorption specific surface area measured using the BET (Brunauer-Emmett-Teller) method. The G / D ratio is the peak intensity ratio of the G band to the D band in the Raman spectrum of a conductive carbon material such as carbon nanotubes (CNTs) measured using a Raman spectrometer.

[0027]

[16] A slurry composition for an electrochemical element electrode, comprising a conductive carbon material as a conductive material, an electrode active material, the conductive material dispersion composition for an electrochemical element according to any one of [1] to

[13] above, and a solvent.

[0028]

[17] An electrode for an electrochemical element, comprising an electrode mixture layer formed on a current collector foil, the electrode mixture layer being made of a dried product of the slurry composition for an electrochemical element electrode according to

[16] above.

[0029]

[18] An electrochemical element comprising the electrode for an electrochemical element according to

[17] above.

[0030] According to the present invention, it is possible to provide a conductive material dispersion composition for electrochemical elements that can improve the dispersibility of a conductive material for electrochemical elements. Also, according to the present invention, it is possible to provide a conductive material dispersion liquid for electrochemical elements that has excellent dispersibility. Furthermore, according to the present invention, it is possible to provide a slurry composition for electrochemical element electrodes that includes the above-mentioned conductive material dispersion composition for electrochemical elements. And according to the present invention, it is possible to provide an electrode for electrochemical elements formed using the above-mentioned slurry composition for electrochemical element electrodes, and an electrochemical element including such an electrode.

[0031] Hereinafter, embodiments of the present invention will be described in detail. Hereinafter, the conductive material dispersion composition for electrochemical elements of the present invention (hereinafter also simply referred to as "dispersion composition") can be used, for example, when preparing the conductive material dispersion liquid for electrochemical elements of the present invention (hereinafter also simply referred to as "conductive material dispersion liquid") and the slurry composition for electrochemical element electrodes of the present invention (hereinafter also simply referred to as "slurry composition"). Furthermore, the slurry composition of the present invention can be used when preparing an electrode mixture layer of the electrode for electrochemical elements of the present invention (hereinafter also simply referred to as "electrode"). The electrochemical element of the present invention comprises the electrode of the present invention.

[0032] (Conductive Material Dispersion Composition for Electrochemical Elements) The conductive material dispersion composition for electrochemical elements of the present invention is characterized by comprising a compound A having two or more functional groups and a polymer A. The compound A having two or more functional groups has two or more functional groups selected from the group consisting of a cyano group, a carboxyl group, and a phenyl group. The two or more functional groups may be the same or different. When used to disperse a conductive material, the dispersion composition of the present invention can disperse the conductive material well. Although the reason for this is not clear, it is presumed that the compound A having two or more specified functional groups acts to increase the wettability of the conductive material, particularly the conductive carbon material, in the dispersion liquid, thereby improving the dispersibility of the conductive material, especially in the initial dispersion stage. Furthermore, it is believed that the polymer A can easily enter the gaps between aggregates of the conductive material with increased wettability, thereby improving the dispersion stability of the conductive material in the dispersion liquid. Furthermore, the effect of improving the wettability of the conductive material imparted by Polymer A makes it possible to shorten the time required for dispersion treatment and is thought to be able to prevent excessive fragmentation of conductive carbon materials such as CNTs due to excessive dispersion treatment, which is thought to promote the formation of a good conductive network in the electrode and reduce the IV resistance of the resulting electrochemical device.

[0033] <Compound A having two or more functional groups> Compound A having two or more functional groups has two or more functional groups selected from the group consisting of a cyano group, a carboxyl group, and a phenyl group. Such compound A is a component that acts to increase the wettability of a conductive material, particularly a conductive carbon material, when a conductive material dispersion liquid is prepared. Whether compound A has two or more predetermined functional groups can be determined, for example, by １ H-NMR and １３ This can be verified using nuclear magnetic resonance (NMR) techniques such as C-NMR.

[0034] The two or more functional groups possessed by compound A may be the same or different from one another. In particular, from the viewpoint of efficiently increasing the wettability of the conductive material, it is preferable that the multiple functional groups are the same. Furthermore, the upper limit of the number of the predetermined functional groups possessed by compound A is not particularly limited. However, when compound A having two or more functional groups is a so-called polymer or oligomer containing repeating units of monomer units, the upper limit of the number of the predetermined functional groups possessed by compound A is preferably 100 or less, more preferably 80 or less, and even more preferably 60 or less. Furthermore, when compound A having two or more functional groups is not a polymer or oligomer, the upper limit of the number of the predetermined functional groups possessed by compound A is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less. When the number of the predetermined functional groups possessed by compound A is two or more, the wettability of the conductive material, particularly the conductive carbon material, can be increased, and the dispersibility of the conductive material can be effectively improved, particularly in the initial dispersion stage. Furthermore, when the number of the predetermined functional groups possessed by compound A is equal to or less than the upper limit, the affinity with the conductive material can be appropriately increased, and the wettability can be effectively improved. This is presumably because, when the number of the predetermined functional groups possessed by compound A is equal to or less than the upper limit, the number of adsorption points possessed by compound A can be prevented from becoming excessively large, and compound A can be allowed to penetrate deep into the aggregates of the conductive material.

[0035] Here, compound A having two or more predetermined functional groups may have two or more predetermined functional groups at any site within compound A. Furthermore, compound A preferably has a linear or branched alkylene chain from the viewpoint of increasing the affinity for conductive carbon materials such as CNTs and effectively enhancing wettability, and more preferably has a linear alkylene chain from the viewpoint of further enhancing the initial dispersibility of the conductive material. This is because the chain consisting of a C-C single bond in the alkylene chain has excellent affinity with conductive carbon materials. Therefore, compound A preferably has a structure including an alkylene chain and in which the alkylene chain is substituted with at least two of the above-described predetermined functional groups.

[0036] <<Specific Examples of Compound A>> Specific examples of compound A having two or more functional groups include, but are not limited to, the following compounds. Examples include compounds having two cyano groups, such as succinonitrile (1,2-dicyanoethane), glutaronitrile (1,3-dicyanopropane), adiponitrile (1,4-dicyanobutane), pimelonitrile (1,5-dicyanopentane), suberonitrile (1,6-dicyanohexane), nonanedinitrile (1,7-dicyanoheptane), sebaconitrile (1,8-dicyanooctane), undecanedinitrile (1,9-dicyanononane), and dodecanedinitrile (1,10-dicyanodecane). These compounds may be linear dinitrile compounds having cyano groups at both ends of the main alkylene chain. Further examples include compounds having three cyano groups, such as 1,2,3-propanetricarbonitrile, 1,2,4-butanetricarbonitrile, 1,3,5-pentanetricarbonitrile, 1,3,6-hexanetricarbonitrile, and 1,3,5-heptanetricarbonitrile. Such compounds may be nitrile compounds having cyano groups at both ends of the alkylene chain that is the main chain, and having one cyano group as a substituent on a carbon atom other than those at both ends of the alkylene chain. Other examples include compounds having two carboxyl groups, such as succinic acid (1,2-ethanedicarboxylic acid), glutaric acid (1,3-propanedicarboxylic acid), adipic acid (1,4-butanedicarboxylic acid), pimelic acid (1,5-pentanedicarboxylic acid), suberic acid (1,6-hexanedicarboxylic acid), azelaic acid (1,7-heptanedicarboxylic acid), sebacic acid (1,8-octanedicarboxylic acid), 1,9-nonanedicarboxylic acid, and dodecanedioic acid (1,10-decanedicarboxylic acid). Such compounds may be carboxylic acids having carboxyl groups at both ends of the main alkylene chain. Further examples include compounds having one phenyl group and one nitrile group, such as 4-phenylbutyronitrile and 2-phenylbutyronitrile. Further examples include compounds having a cyano group and a carboxyl group, such as cyanoacetic acid, 2-cyanopropanoic acid, 2-cyano-2-methylpropanoic acid, 2-cyanopentanoic acid, and 2-cyano-3,3-dimethylbutanoic acid.Further examples include compounds having a cyano group, a carboxyl group, and a phenyl group, such as 2-cyano-3-phenylpropionic acid.

[0037] In addition to the compounds described above, polymers or oligomers containing at least two of a cyano group-containing monomer unit, a carboxyl group-containing monomer unit, and a phenyl group-containing monomer unit may be used. Examples of cyano group-containing monomer units include nitrile group-containing monomer units such as (meth)acrylonitrile monomer units, allyl cyanide units, fumaronitrile units, 3-hexenedinitrile units, and 2-cyanoethyl acrylate units. Examples of carboxyl group-containing monomer units include (meth)acrylic acid monomer units, maleic acid monomer units, crotonic acid monomer units, itaconic acid monomer units, and fumaric acid monomer units. Examples of phenyl group-containing monomer units include aromatic vinyl monomer units such as styrene monomer units. Specific examples of the polymer or oligomer that can be compound A containing two or more predetermined functional groups include a styrene-acrylonitrile copolymer, which is a copolymer containing a phenyl group-containing monomer unit and a nitrile group-containing monomer unit; and poly(meth)acrylonitrile and polyallyl cyanide containing a nitrile group-containing monomer unit.

[0038] <<Molecular Weight of Compound A>> The compound A having two or more functional groups preferably has a molecular weight of 70 or more, more preferably 85 or more, and preferably 8,000 or less, more preferably 6,000 or less, even more preferably 4,000 or less, even more preferably 3,000 or less, and particularly preferably 2,000 or less. Note that the molecular weight refers to the weight-average molecular weight when compound A is a so-called polymer or oligomer containing repeating units of a monomer unit; otherwise, it refers to the sum of the atomic weights of the constituent elements of compound A. If the molecular weight of compound A having two or more functional groups is equal to or greater than the above-mentioned lower limit, the dispersibility of the conductive material, particularly the dispersion stability, can be further improved. Furthermore, if the molecular weight of compound A having two or more functional groups is equal to or less than the above-mentioned upper limit, the dispersibility of the conductive material, particularly the initial dispersibility when the conductive material, the dispersion medium, and the dispersion composition are mixed and dispersed, can be further improved, and the IV resistance of the resulting electrochemical device can be reduced. In addition, the molecular weight of the compound A is preferably lower than the weight average molecular weight of the polymer A described below, from the viewpoint of further improving the initial dispersibility of the conductive material.

[0039] <Polymer A> The polymer A contained in the dispersion composition is a component that, when a conductive material dispersion is prepared, penetrates into the gaps between the conductive material and imparts steric repulsion, thereby functioning to enhance the dispersion stability of the conductive material in the conductive material dispersion. The polymer A can also be a component that can exert the function of retaining the components contained in the electrode mixture layer so that they do not detach from the electrode mixture layer. Here, it is preferable that the polymer A contains a linear alkylene structural unit having 4 or more carbon atoms and a nitrile-containing monomer unit. If the polymer A contains a linear alkylene structural unit having 4 or more carbon atoms and a nitrile-containing monomer unit, the affinity between the polymer A and the conductive material can be increased, and ultimately the dispersibility of the conductive material for electrochemical elements can be further improved. The content ratio (mass%) of each monomer unit in the polymer A is １ It can be measured using a nuclear magnetic resonance (NMR) method such as H-NMR.

[0040] [Straight-chain alkylene structural unit having 4 or more carbon atoms] The straight-chain alkylene structural unit having 4 or more carbon atoms is represented by the general formula: -Cｎ H ２ｎ - [where n is an integer of 4 or more]. Since polymer A has a linear alkylene structural unit having 4 or more carbon atoms, it can improve the dispersibility of the conductive material.

[0041] Here, the method for introducing linear alkylene structural units having 4 or more carbon atoms into polymer A is not particularly limited, and examples thereof include the following methods (1) and (2): (1) a method of preparing polymer A from a monomer composition containing a conjugated diene monomer and hydrogenating the polymer A to convert the conjugated diene monomer units into linear alkylene structural units having 4 or more carbon atoms; and (2) a method of preparing polymer A from a monomer composition containing a 1-olefin monomer. Among these, method (1) is preferred because it allows for easy production of polymer A.

[0042] Examples of conjugated diene monomers include conjugated diene compounds having 4 or more carbon atoms, such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. Of these, 1,3-butadiene is preferred. That is, the linear alkylene structural unit having 4 or more carbon atoms is preferably a structural unit (conjugated diene hydride unit) obtained by hydrogenating a conjugated diene monomer unit, and more preferably a structural unit (1,3-butadiene hydride unit) obtained by hydrogenating a 1,3-butadiene unit. Selective hydrogenation of the conjugated diene monomer unit can be carried out using known methods such as oil phase hydrogenation and aqueous phase hydrogenation. Examples of 1-olefin monomers include ethylene, propylene, 1-butene, and 1-hexene. These conjugated diene monomers and 1-olefin monomers can be used alone or in combination of two or more.

[0043] The content of linear alkylene structural units having 4 or more carbon atoms in polymer A is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, particularly preferably 50% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less, and even more preferably 70% by mass or less, when the total amount of repeating units in polymer A (the sum of structural units and monomer units) is taken as 100% by mass. By setting the content of alkylene structural units to the above-mentioned lower limit or more, the dispersibility of the conductive material can be further improved. Furthermore, by setting the content of alkylene structural units to the above-mentioned upper limit or less, a decrease in the solubility of polymer A in solvents such as N-methylpyrrolidone (NMP) can be suppressed, and polymer A can fully exhibit its dispersibility effect for the conductive material, thereby reducing the IV resistance of the resulting electrochemical device.

[0044] When the linear alkylene structural unit having 4 or more carbon atoms is a structural unit (conjugated diene hydride unit) obtained by hydrogenating a conjugated diene monomer unit, it is preferable that the total content of the conjugated diene monomer unit and the linear alkylene structural unit having 4 or more carbon atoms in the polymer A satisfies the above range.

[0045] [Nitrile Group-Containing Monomer Unit] The nitrile group-containing monomer unit is a repeating unit derived from a nitrile group-containing monomer. Since the polymer A contains the nitrile group-containing monomer unit, it can further improve the dispersibility of the conductive material and can also exhibit excellent flexibility and binding strength.

[0046] Here, examples of nitrile group-containing monomers capable of forming nitrile group-containing monomer units include α,β-ethylenically unsaturated nitrile monomers. Specifically, the α,β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α,β-ethylenically unsaturated compound having a nitrile group, but examples include acrylonitrile; α-halogenoacrylonitriles such as α-chloroacrylonitrile and α-bromoacrylonitrile; and α-alkylacrylonitriles such as methacrylonitrile and α-ethylacrylonitrile. Among these, from the viewpoint of improving the dispersibility (particularly initial dispersibility) of the conductive material by polymer A and from the viewpoint of increasing the binding strength of polymer A, acrylonitrile and methacrylonitrile are preferred as nitrile group-containing monomers, with acrylonitrile being more preferred. These may be used alone or in combination of two or more.

[0047] The content of the nitrile group-containing monomer units in polymer A is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 20% by mass or more, and preferably 50% by mass or less, and more preferably 40% by mass or less, when the total amount of repeating units in polymer A is taken as 100% by mass. By setting the content of the nitrile group-containing monomer units in polymer A to the above-mentioned lower limit or more, it is possible to improve the dispersibility of the conductive material (particularly the initial dispersibility) by polymer A and the binding strength of polymer A. Furthermore, by setting the content of the nitrile group-containing monomer units in polymer A to the above-mentioned upper limit or less, it is possible to suppress elution of polymer A into the electrolytic solution.

[0048] [Other Repeating Units] The other repeating units other than the above-described alkylene structural units and nitrile group-containing monomer units are not particularly limited, and examples thereof include repeating units derived from known monomers copolymerizable with the above-described monomers, such as acid group-containing monomer units and aromatic vinyl monomer units.

[0049] [Aromatic vinyl monomer unit] Examples of aromatic vinyl monomers that can form aromatic vinyl monomer units include styrene, α-methylstyrene, vinyltoluene, divinylbenzene, etc. These may be used alone or in combination of two or more. Among these, styrene is preferred.

[0050] [Acid group-containing monomer unit] Examples of acid group-containing monomers that can form acid group-containing monomer units include carboxyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, etc. The acid group in the acid group-containing monomer unit may form a salt with an alkali metal, ammonia, etc.

[0051] Here, examples of carboxyl group-containing monomers capable of forming carboxyl group-containing monomer units include monocarboxylic acids and their derivatives, dicarboxylic acids and their acid anhydrides, and their derivatives. Examples of monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of monocarboxylic acid derivatives include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, and α-chloro-β-E-methoxyacrylic acid. Examples of dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Examples of dicarboxylic acid derivatives include methylmaleic acid, dimethylmaleic acid, phenylmaleic acid, chloromaleic acid, dichloromaleic acid, fluoromaleic acid, and maleic acid monoesters such as monobutyl maleate, monononyl maleate, monodecyl maleate, monododecyl maleate, monooctadecyl maleate, and monofluoroalkyl maleate. Examples of dicarboxylic acid anhydrides include maleic anhydride, acrylic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, and citraconic anhydride. Furthermore, acid anhydrides that generate carboxyl groups upon hydrolysis can also be used as carboxyl group-containing monomers. Furthermore, examples of carboxyl group-containing monomers that can be used include ethylenically unsaturated polycarboxylic acids such as butenetricarboxylic acid, and partial esters of ethylenically unsaturated polycarboxylic acids such as monobutyl fumarate and mono-2-hydroxypropyl maleate.

[0052] Examples of sulfonic acid group-containing monomers capable of forming sulfonic acid group-containing monomer units include styrenesulfonic acid, vinylsulfonic acid (ethylenesulfonic acid), methylvinylsulfonic acid, (meth)allyl sulfonic acid, and 3-allyloxy-2-hydroxypropanesulfonic acid. In the present invention, "(meth)allyl" means allyl and / or methallyl.

[0053] Furthermore, examples of the phosphate group-containing monomer capable of forming the phosphate group-containing monomer unit include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate. In the present invention, "(meth)acryloyl" means acryloyl and / or methacryloyl.

[0054] The above-mentioned monomers may be used singly or in combination of two or more. As the acid group-containing monomer capable of forming the acid group-containing monomer unit, methacrylic acid, itaconic acid, and acrylic acid are preferred, and methacrylic acid is more preferred.

[0055] Here, the content of the other repeating units in polymer A is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. The lower limit of the content of the other repeating units in polymer A is not particularly limited, and can be, for example, 0% by mass or 1% by mass or more. From the viewpoint of further improving the dispersion stability of the conductive material, it is preferably less than 3% by mass.

[0056] <<Weight-Average Molecular Weight of Polymer A>> The weight-average molecular weight of polymer A is preferably 3,000 or more, more preferably 8,000 or more, even more preferably 15,000 or more, and preferably 500,000 or less, more preferably 400,000 or less, and even more preferably 300,000 or less. When the weight-average molecular weight of polymer A is equal to or greater than the above-mentioned lower limit, the dispersion stability of the conductive material can be further improved. When the weight-average molecular weight of polymer A is equal to or less than the above-mentioned upper limit, the wettability of the conductive material can be improved and the IV resistance of the resulting electrochemical device can be reduced. When polymer A, which is blended into the dispersion composition and functions as a dispersant for the conductive material, has a weight-average molecular weight within the above-mentioned range, it can impart steric repulsion to the conductive material dispersed in the conductive material dispersion composition and the slurry composition. This can improve the dispersion stability of the conductive material in the conductive material dispersion composition and the slurry composition. Furthermore, when preparing a conductive material dispersion or the like, by using polymer A in combination with the above-mentioned compound A, compound A first acts to widen the gaps between the conductive material at the initial stage of dispersion, so that polymer A, which has difficulty entering the gaps between the conductive material at the initial stage of dispersion due to steric repulsion, becomes more likely to enter the gaps between the conductive material, and as a result, the dispersion stability of the conductive material in the dispersion can be dramatically improved. Note that, from the viewpoint of further improving the initial dispersibility of the conductive material, it is preferable that the weight-average molecular weight of polymer A is larger than the weight-average molecular weight of the above-mentioned compound A. This is because, if the weight-average molecular weight of polymer A is larger than the weight-average molecular weight of compound A, the conductive material, whose dispersibility has been improved first by the action of compound A, is promoted to be further improved by polymer A.

[0057] <<Iodine Value of Polymer A>> Here, the iodine value of polymer A is more preferably 100 mg / 100 mg or less, even more preferably 70 mg / 100 mg or less, even more preferably 40 mg / 100 mg or less, and particularly preferably 20 mg / 100 mg or less. When the iodine value of polymer A is 100 mg / 100 mg or less, the oxidation resistance of polymer A can be well ensured. The lower limit of the iodine value of polymer A is not particularly limited, but may be, for example, 3 mg / 100 mg or more, or may be 5 mg / 100 mg or more. The iodine value of polymer A can be adjusted, for example, by changing the hydrogenation conditions during the production of polymer A.

[0058] <<Method for Preparing Polymer A>> The method for preparing the above-mentioned polymer A is not particularly limited, and for example, the polymer A can be prepared by polymerizing a monomer composition containing the above-mentioned monomers, optionally in the presence of a chain transfer agent, to obtain a polymer, and then hydrogenating (hydrogenating) the obtained polymer.

[0059] Here, the content ratio of each monomer in the monomer composition used to prepare polymer A can be determined in accordance with the content ratio of each repeating unit in polymer A. The polymerization method is not particularly limited, and any method such as solution polymerization, suspension polymerization, bulk polymerization, or emulsion polymerization can be used. Furthermore, any reaction such as ionic polymerization, radical polymerization, or living radical polymerization can be used as the polymerization reaction. Commonly used emulsifiers, dispersants, polymerization initiators, chain transfer agents, and the like can be used in common amounts. Among these, tert-dodecyl mercaptan is preferred as the chain transfer agent. The amount of the chain transfer agent added is preferably 0.1 parts by mass or more and 2.5 parts by mass or less, based on 100 parts by mass of the monomer amount in the monomer composition used in the polymerization reaction. Furthermore, the polymerization temperature is preferably 0°C or more and 50°C or less.

[0060] Furthermore, the method for hydrogenating the polymer is not particularly limited, and a general method using a catalyst (see, for example, WO 2012 / 165120, WO 2013 / 080989, and JP 2013-8485 A) can be used.

[0061] <<Amount Ratio of Polymer A to Compound A>> In the dispersion composition, the total mass of polymer A and compound A having two or more functional groups is 100 parts by mass, and the blending ratio of compound A is preferably 10 parts by mass or more, more preferably 18 parts by mass or more, and preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and more preferably 32 parts by mass or less. If the blending ratio of compound A having two or more functional groups is equal to or greater than the above-mentioned lower limit, the dispersibility of the conductive material can be further improved and the IV resistance of the resulting electrochemical device can be reduced. Furthermore, if the blending ratio of compound A having two or more functional groups is equal to or less than the above-mentioned upper limit, the dispersion stability of the conductive material can be further improved and the IV resistance of the resulting electrochemical device can be reduced.

[0062] <Other Components> The dispersion composition can contain components (other components) other than the above-described polymer A and compound A having two or more functional groups. For example, the dispersion composition may contain a solvent and a known polymer component other than the above-described polymer A (such as a copolymer of polyethylene glycol and styrene, a styrene-maleic acid copolymer, an acrylic acid copolymer, and polyvinylpyrrolidone). Solvents described below can be used. The dispersion composition may also contain a monomer (unreacted residual monomer) used in producing polymer A and known additives. The proportion of other components in the total solid content contained in the dispersion composition is not particularly limited, but is usually 10 mass % or less.

[0063] Examples of such known additives include dispersants different from the above-mentioned compound A, such as pigment dispersants (dispersants that do not satisfy the above-mentioned condition of having two or more specified functional groups), antioxidants, etc. These are not particularly limited as long as they do not affect the reaction of the electrochemical device, and known additives can be used. Note that the other components may be used alone or in combination of two or more in any ratio.

[0064] (Conductive material dispersion for electrochemical elements) The conductive material dispersion for electrochemical elements is characterized by containing a conductive carbon material as a conductive material, a solvent, and the above-mentioned dispersion composition. That is, the conductive material dispersion for electrochemical elements contains at least a conductive carbon material as a conductive material, a solvent, a compound A having two or more functional groups, and a polymer A, and may optionally contain other components. Such a conductive material dispersion for electrochemical elements has excellent dispersibility, and therefore can reduce the IV resistance of the obtained electrochemical element.

[0065] (Conductive Material) The conductive carbon material used as the conductive material in the conductive material dispersion of the present invention preferably contains carbon nanotubes (CNTs). For example, the conductive material dispersion of the present invention may contain only CNTs as the conductive carbon material, or may contain CNTs and conductive carbon materials other than CNTs. Examples of CNTs include single-walled and multi-walled CNTs (multi-walled CNTs include cup-stacked CNTs). Furthermore, the CNTs may further contain conductive carbon materials such as carbon black (e.g., acetylene black, Ketjen Black (registered trademark), furnace black, etc.), carbon nanohorns, milled carbon fibers obtained by calcining and then crushing polymer fibers, single-walled or multi-walled graphene, and carbon nonwoven fabric sheets obtained by calcining nonwoven fabrics made of polymer fibers; fibers or foils of various metals, etc. These may be used alone, or two or more may be used in any combination.

[0066] Furthermore, the conductive carbon material has a BET specific surface area of ​​150 m ２ / g or more, and ２ / g or more, and ２ / g or more, and ２ / g or less, and ２ / g or less is more preferable, and 600m ２ / g or less is even more preferable. When the BET specific surface area is equal to or greater than the above lower limit, a good conductive network can be formed in the electrode, and the IV resistance of the resulting electrochemical device can be reduced. Furthermore, when the BET specific surface area is equal to or less than the above upper limit, aggregation of the conductive carbon material in the conductive material dispersion can be suppressed, and dispersion stability can be further improved.

[0067] Furthermore, the conductive carbon material preferably has a G / D ratio determined by Raman spectroscopy of 0.4 or more, more preferably 0.6 or more, and preferably 20 or less, more preferably 10 or less. If the G / D ratio is equal to or greater than the above-mentioned lower limit, the electrochemical performance such as electrical conductivity of the resulting electrochemical element can be improved. If the G / D ratio is equal to or less than the above-mentioned upper limit, the dispersibility of the conductive material in the dispersion can be improved. Here, the Raman spectrum of the conductive carbon material (specifically, CNT) measured by a Raman spectrometer contains a G band (1600 cm －１ around 1350 cm －１ A vibration mode called the G band (near the G band) is observed. The G band is a vibration mode derived from the hexagonal lattice structure of graphite, which is the cylindrical surface of the CNT, and the D band is a vibration mode derived from the amorphous part. Therefore, the higher the peak intensity ratio of the G band to the D band (G / D ratio), the more highly crystalline the CNT can be evaluated.

[0068] <<Conductive Material Content>> Here, the content of the conductive material (particularly CNT as a conductive carbon material) in the conductive material dispersion is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 1% by mass or more, particularly preferably 2% by mass or more, preferably 10% by mass or less, more preferably 9% by mass or less, even more preferably 8% by mass or less, and particularly preferably 7% by mass or less, based on the total amount of the conductive material dispersion being 100% by mass. If the content of the conductive material (particularly CNT as a conductive carbon material) in the conductive material dispersion is 0.05% by mass or more, an excessive decrease in the solid content concentration during preparation of an electrode slurry can be suppressed. Furthermore, if the content of the conductive material (particularly CNT as a conductive carbon material) in the conductive material dispersion is 10% by mass or less, the viscosity of the conductive material dispersion can be kept low, thereby improving operability.

[0069] <Solvent> The solvent that can be contained in the conductive material dispersion of the present invention is not particularly limited, and examples thereof include water and organic solvents. Examples of organic solvents that can be used include acetonitrile, N-methyl-2-pyrrolidone (NMP), tetrahydrofuran, acetone, acetylpyridine, cyclopentanone, dimethylformamide, dimethyl sulfoxide, methylformamide, methyl ethyl ketone, furfural, ethylenediamine, dimethylbenzene (xylene), methylbenzene (toluene), cyclopentyl methyl ether, and isopropyl alcohol. These may be used alone or in combination of two or more. Among these, NMP is preferred from the viewpoint of reducing the IV resistance of the electrochemical element.

[0070] <Dispersion Composition> The dispersion composition used in the conductive material dispersion liquid is the dispersion composition of the present invention described above. The content of the dispersion composition in the conductive material dispersion liquid is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, preferably 8.0% by mass or less, more preferably 3.5% by mass or less, even more preferably 2.5% by mass or less, and particularly preferably 2.0% by mass or less, based on the total amount of the conductive material dispersion being 100% by mass. If the content of the dispersion composition in the conductive material dispersion liquid is equal to or greater than the above-mentioned lower limit, the initial dispersibility and dispersion stability of the conductive material in the conductive material dispersion liquid can be further improved. If the content of the dispersion composition in the conductive material dispersion liquid is equal to or less than the above-mentioned upper limit, the viscosity of the conductive material dispersion liquid can be reduced, thereby improving operability during electrode production.

[0071] <<Content of Compound A>> Here, the content of compound A in the conductive material dispersion is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and is preferably 3.0% by mass or less, more preferably 1.5% by mass or less, even more preferably 1.0% by mass or less, and particularly preferably 0.5% by mass or less, based on the total amount of the conductive material dispersion being 100% by mass. If the content of compound A in the conductive material dispersion is equal to or greater than the above-mentioned lower limit, the initial dispersibility of the conductive material in the conductive material dispersion can be further improved. Furthermore, if the content of compound A in the conductive material dispersion is equal to or less than the above-mentioned upper limit, the viscosity of the conductive material dispersion can be reduced, thereby improving operability during electrode production.

[0072] <<Content of Polymer A>> Furthermore, the content of polymer A in the conductive material dispersion is preferably 0.09% by mass or more, more preferably 0.25% by mass or more, even more preferably 0.50% by mass or more, and preferably 5.00% by mass or less, more preferably 2.00% by mass or less, even more preferably 1.50% by mass or less, and particularly preferably 1.05% by mass or less, based on the total amount of the conductive material dispersion being 100% by mass. If the content of polymer A in the conductive material dispersion is equal to or greater than the above-mentioned lower limit, the dispersion stability can be further improved. Furthermore, if the content of polymer A in the conductive material dispersion is equal to or less than the above-mentioned upper limit, the viscosity of the conductive material dispersion can be reduced, thereby improving operability during electrode production.

[0073] <Solid content concentration> The solid content concentration of the conductive material dispersion is preferably 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and is preferably 15% by mass or less, more preferably 12.5% ​​by mass or less, and even more preferably 10% by mass or less. If the solid content concentration in the conductive material dispersion is 0.5% by mass or more, an electrode slurry of a desired concentration can be prepared. On the other hand, if the solid content concentration in the conductive material dispersion is 15% by mass or less, the processability of the electrode slurry prepared using the conductive material dispersion is improved.

[0074] <Other Components> The conductive material dispersion may optionally contain other components in addition to the various components described above. Such components are not particularly limited, and the components described above as other components that may be optionally contained in the dispersion composition, as well as additives known in the technical field, such as emulsifiers and viscosity modifiers, may be used. The amount of such additives to be added is not particularly limited and can be set appropriately as long as it does not impair the effects of the present invention.

[0075] <Preparation of Conductive Material Dispersion for Electrochemical Devices> The conductive material dispersion of the present invention can be prepared, for example, by subjecting a mixed liquid obtained by mixing the dispersion composition of the present invention described above, a conductive carbon material as a conductive material, a solvent, and any other components to a dispersion treatment to obtain a conductive material preliminary dispersion (primary dispersion step), and then subjecting the obtained conductive material preliminary dispersion to a further dispersion treatment to obtain a conductive material dispersion (secondary dispersion step). Prior to the primary dispersion step, a wetting step may be performed to allow compound A, polymer A, and a solvent to penetrate into gaps between aggregates of the conductive carbon material, such as CNT aggregates. It is also possible to blend polymer A after allowing compound A to penetrate the conductive carbon material in the wetting step. The primary dispersion step is intended to disintegrate CNT aggregates contained in the mixed liquid by a relatively weak dispersion treatment. The secondary dispersion step is intended to stabilize the dispersion of CNTs by a stronger dispersion treatment. Dispersion treatments used in the primary dispersion step include ultrasonic treatment, homodisperser, homomixer, etc., and dispersion treatments used in the secondary dispersion step include bead mills, planetary mills, high-pressure homogenizers, etc.

[0076] (Slurry composition for electrochemical element electrode) The electrode slurry composition of the present invention contains at least the above-mentioned dispersion composition, a conductive carbon material as a conductive material, an electrode active material, and a solvent, and optionally further contains other components. That is, the electrode slurry composition of the present invention contains at least polymer A, compound A, a conductive carbon material as a conductive material, a solvent, and an electrode active material, and optionally further contains other components. Since the electrode slurry composition of the present invention contains the above-mentioned dispersion composition of the present invention, use of the electrode slurry composition can reduce the IV resistance of an electrochemical element.

[0077] In the following, an example will be described in which the electrode slurry composition of the present invention is a slurry composition for a lithium ion secondary battery positive electrode, but the present invention is not limited to the following example.

[0078] <Dispersion Composition> As the dispersion composition used in the electrode slurry composition, the dispersion composition of the present invention described above is used.

[0079] <Electrode Active Material> The electrode active material is a material that transfers between electrodes of a secondary battery. As the positive electrode active material for a lithium ion secondary battery, a material that can absorb and release lithium is usually used.

[0080] Specifically, the positive electrode active material for a lithium ion secondary battery is not particularly limited, and may be a lithium-containing cobalt oxide (LiCoO ２ ), lithium manganese oxide (LiMn ２ O ４ ), lithium-containing nickel oxide (LiNiO ２ ), Co—Ni—Mn lithium-containing composite oxide (Li(CoMnNi)O ２ ), lithium-containing composite oxide of Ni-Mn-Al, lithium-containing composite oxide of Ni-Co-Al (Li(CoNiAl)O ２ ), olivine-type lithium iron phosphate (LiFePO ４ ), olivine-type lithium manganese phosphate (LiMnPO ４ ), Li ２ MnO ３ -LiNiO ２ system solid solution, Li １＋ｘ Mn ２－ｘ O ４ Examples of the positive electrode active material include known positive electrode active materials such as lithium-excess spinel compounds represented by (0<X<2). The amount and particle size of the positive electrode active material are not particularly limited and can be the same as those of conventionally used electrode active materials.

[0081] <Solvent> The solvent used in the electrode slurry composition is the solvent described above.

[0082] The other components are not particularly limited, and examples thereof include known binders (e.g., fluorine-containing polymers such as polyvinylidene fluoride) that are commonly used in electrodes for electrochemical elements, and other components that can be blended into the dispersion composition of the present invention.

[0083] <Preparation of Slurry Composition for Electrochemical Device Electrode> The electrode slurry composition of the present invention can be prepared by mixing the above-described dispersion composition, a conductive material, a solvent, an electrode active material, and any other components. Here, the mixing method is not particularly limited, and the same method as used to prepare the above-described dispersion composition of the present invention can be used. Furthermore, the order in which the above-described components are mixed is not particularly limited, and all of the components to be incorporated into the dispersion composition, the conductive material, the solvent, the electrode active material, and any other components may be mixed together, or, for example, the above-described conductive material dispersion may be prepared, and then the resulting conductive material dispersion may be mixed with the electrode active material and any other components.

[0084] (Electrode for electrochemical device) The electrode for electrochemical device of the present invention comprises, for example, an electrode mixture layer formed on a current collector using the above-mentioned electrode slurry composition. Specifically, the electrode mixture layer is usually made of a dried product of the above-mentioned electrode slurry composition, and the electrode mixture layer contains at least the above-mentioned polymer A, compound A, a conductive carbon material as a conductive material, and an electrode active material, and optionally contains other components. Note that the components contained in the electrode mixture layer are those contained in the above-mentioned electrode slurry composition, and the preferred abundance ratio of each of these components is the same as the preferred abundance ratio of each component in the electrode slurry composition.

[0085] Furthermore, in the electrode for an electrochemical element of the present invention, the electrode mixture layer is formed using the above-mentioned electrode slurry composition, and therefore the IV resistance of the electrochemical element can be reduced.

[0086] <Method for forming an electrode for an electrochemical element> Here, the electrode mixture layer of the electrode for an electrochemical element of the present invention can be formed on a current collector through, for example, a step of applying the above-mentioned electrode slurry composition onto a current collector (application step), and a step of drying the electrode slurry composition applied onto the current collector to form an electrode mixture layer on the current collector (drying step).

[0087] <<Coating Step>> The method for applying the electrode slurry composition onto the current collector is not particularly limited, and known methods can be used. Specifically, examples of the coating method that can be used include a comma coater method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method. In this case, the electrode slurry may be applied to only one surface of the current collector, or may be applied to both surfaces of the current collector. The thickness of the electrode slurry film on the current collector after application and before drying can be appropriately set depending on the thickness of the electrode mixture layer obtained by drying.

[0088] Here, a material that is electrically conductive and electrochemically durable is used as the current collector to which the electrode slurry composition is applied. Specifically, the current collector may be made of, for example, iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. Note that the above-mentioned materials may be used alone or in combination of two or more in any ratio.

[0089] <<Drying Step>> The method for drying the electrode slurry composition on the current collector is not particularly limited, and known methods can be used, such as drying with warm air, hot air, or low-humidity air, vacuum drying, and drying by irradiation with infrared rays or electron beams. By drying the electrode slurry composition on the current collector in this manner, an electrode mixture layer is formed on the current collector, and an electrode for an electrochemical device comprising the current collector and the electrode mixture layer can be obtained. After the drying step, the electrode mixture layer may be subjected to a pressure treatment using a mold press or a roll press. The pressure treatment can further improve the adhesion between the electrode mixture layer and the current collector.

[0090] (Electrochemical element) The electrochemical element of the present invention is not particularly limited, and may be a lithium ion secondary battery or an electric double layer capacitor, preferably a lithium ion secondary battery. The electrochemical element of the present invention has a low IV resistance because it includes the electrode for an electrochemical element of the present invention.

[0091] Hereinafter, a case where the electrochemical element is a lithium ion secondary battery will be described as an example, but the present invention is not limited to the following example. A lithium ion secondary battery as the electrochemical element of the present invention usually comprises electrodes (positive electrode and negative electrode), an electrolyte, and a separator, and the electrode for electrochemical elements of the present invention is used for at least one of the positive electrode and the negative electrode. In particular, it is preferable that the positive electrode is the electrode for electrochemical elements of the present invention.

[0092] <Electrode> Here, the electrode other than the above-described electrode for an electrochemical element that can be used in the lithium ion secondary battery as the electrochemical element of the present invention is not particularly limited, and any known electrode can be used. Specifically, the electrode other than the above-described electrode for an electrochemical element can be an electrode obtained by forming an electrode mixture layer on a current collector using a known manufacturing method.

[0093] <Electrolyte> As the electrolyte, an organic electrolyte solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. As the supporting electrolyte of a lithium ion secondary battery, for example, a lithium salt is used. As the lithium salt, for example, LiPF ６ , LiAsF ６ , LiBF ４ , LiSbF ６ , LiAlCl ４ , LiClO ４ , C.F. ３ SO ３ Li, C ４ F ９ SO ３ Li, CF ３ COOLi, (CF ３ CO) ２ NLi, (CF ３ SO ２ ) ２ NLi, (C ２ F ５ SO ２ Among them, LiPF is the most popular because it is easily soluble in solvents and shows a high degree of dissociation. ６ , LiClO ４ , C.F. ３ SO ３ Li is preferred, and LiPF ６is particularly preferred. The electrolyte may be used alone or in combination of two or more kinds in any ratio. Generally, the lithium ion conductivity tends to increase as the supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of supporting electrolyte.

[0094] The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte. For example, carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), and ethyl methyl carbonate (EMC) are preferably used. Other suitable solvents include carbonates such as γ-butyrolactone and methyl formate, ethers such as 1,2-dimethoxyethane and tetrahydrofuran, and sulfur-containing compounds such as sulfolane and dimethyl sulfoxide. Mixtures of these solvents may also be used. Among these, carbonates are preferred because of their high dielectric constant and wide stable potential range, and a mixture of ethylene carbonate and ethyl methyl carbonate is even more preferred. The concentration of the electrolyte in the electrolyte can be adjusted as appropriate. Known additives, such as vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethyl methyl sulfone, may also be added to the electrolyte.

[0095] <Separator> The separator is not particularly limited, and for example, those described in JP 2012-204303 A can be used. Among these, a microporous film made of a polyolefin resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred because it allows the thickness of the entire separator to be thin, thereby increasing the proportion of electrode active material in the lithium ion secondary battery and increasing the capacity per volume.

[0096] <Method for Manufacturing Lithium-Ion Secondary Battery> The lithium-ion secondary battery as an electrochemical element of the present invention can be manufactured, for example, by stacking a positive electrode and a negative electrode with a separator interposed therebetween, rolling or folding the resulting assembly as necessary according to the battery shape, placing it in a battery container, injecting an electrolyte into the battery container, and sealing it. To prevent internal pressure increases, overcharge and overdischarge, and the like, a fuse, an overcurrent prevention element such as a PTC element, an expanded metal, a lead plate, or the like may be provided as necessary. The shape of the lithium-ion secondary battery may be any shape, such as a coin type, a button type, a sheet type, a cylindrical type, a rectangular type, or a flat type.

[0097] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified. Furthermore, in a polymer produced by polymerizing multiple types of monomers, the proportion of a monomer unit formed by polymerizing a certain monomer in the polymer usually coincides with the ratio (feed ratio) of that certain monomer to all monomers used in the polymerization of the polymer, unless otherwise specified. In the examples and comparative examples, various measurements and evaluations were carried out as follows.

[0098] <Weight-average molecular weight> The weight-average molecular weight (Mw) of polymer A prepared in the examples and comparative examples, and compound A (polyallyl cyanide) prepared in Example 14 was measured by gel permeation chromatography (GPC) using a 10 mM LiBr-DMF solution under the following measurement conditions: Separation column: Shodex KD-806M (manufactured by Showa Denko K.K.) Detector: differential refractometer detector RID-10A (manufactured by Shimadzu Corporation) Eluent flow rate: 0.3 mL / min Column temperature: 40°C Standard polymer: TSK standard polystyrene (manufactured by Tosoh Corporation)

[0099] <Iodine Value> 100 g of the aqueous dispersion of polymer A prepared in the Examples and Comparative Examples was coagulated with 1 L of methanol and then vacuum dried for 12 hours at a temperature of 60° C. The hydrogenated nitrile-butadiene rubber that was coagulated, filtered, and dried was vacuum dried for 12 hours at a temperature of 60° C. The iodine value of the obtained dried polymer was measured in accordance with JIS K6235 (2006).

[0100] <BET Specific Surface Area of ​​Conductive Carbon Material> The BET specific surface area of ​​the conductive carbon material was measured in accordance with JIS Z8830:2013.

[0101] <G / D ratio of conductive carbon material> The Raman spectrum of the conductive carbon material was measured using a microscopic laser Raman spectrophotometer (Nicolet Almega XR manufactured by Thermo Fisher Scientific Co., Ltd.). －１ The intensity of the G band peak observed near 1340 cm －１ The intensity of the D band peak observed in the vicinity was determined, and the G / D ratio was calculated.

[0102] <Conductive material dispersibility (initial)> In the process of preparing a conductive material dispersion in the examples and comparative examples, the conductive material preliminary dispersion obtained at the stage of completing the primary dispersion step of the conductive material dispersion was measured using a rheometer (MCR302 manufactured by Anton Paar) at a temperature of 25°C and a shear rate of 1 s -1 The viscosity was measured under the above conditions and evaluated according to the following criteria. Note that, at the same solid content concentration, the lower the viscosity of the dispersion, the better the dispersibility of the conductive material in the dispersion. A: 90 mPa·s or less B: More than 90 mPa·s and 110 mPa·s or less C: More than 110 mPa·s and 130 mPa·s or less D: More than 130 mPa·s

[0103] <Conductive material dispersion stability> For the conductive material dispersions obtained in the examples and comparative examples, the viscosity measured immediately after preparation was defined as V0, and the viscosity measured after standing for one week in an environment at 40°C was defined as V1. The degree of viscosity increase was calculated according to the formula: V1 / V0 x 100 (%), and evaluated according to the following criteria. The viscosity measurement conditions were a temperature of 25°C, a shear rate of 1 s -1The lower the degree of viscosity increase, the more excellent the dispersion stability of the conductive material dispersion. A: 120% or less B: More than 120% and 140% or less C: More than 140% and 160% or less D: More than 160%

[0104] <IV Resistance of Electrochemical Device> The lithium-ion secondary batteries prepared in the Examples and Comparative Examples were left at 25°C for 5 hours after injection of the electrolyte. Next, the batteries were charged to a cell voltage of 4.2 V at a constant current of 0.2 C and discharged to a cell voltage of 3.0 V, and this charge-discharge cycle was repeated three times to measure the initial capacity. After charging to a depth of charge (SOC) of 50%, the batteries were charged for 20 seconds and discharged for 20 seconds at 0.5 C, 1.0 C, 1.5 C, and 2.0 C, centered around 50% SOC. The battery voltage after 20 seconds in each case (on the charge side and the discharge side) was plotted against the current value, and the slope was calculated as the IV resistance (Ω) (IV resistance during charging and IV resistance during discharging). The obtained IV resistance values ​​(Ω) were evaluated according to the following criteria. A smaller IV resistance value indicates a lower internal resistance. A: 2.2Ω or less B: More than 2.2Ω and 2.35Ω or less C: More than 2.35Ω and less than 2.5Ω D: More than 2.5Ω

[0105] Example 1 Preparation of Polymer A A reactor was charged with 200 parts of ion-exchanged water, 25 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate, 35 parts of acrylonitrile as a nitrile group-containing monomer, and 0.4 parts of t-dodecyl mercaptan as a chain transfer agent, in that order. The internal gas was then purged with nitrogen three times, and 65 parts of 1,3-butadiene as a conjugated diene monomer was then charged. The reactor was then maintained at 10°C, and 0.03 parts of cumene hydroperoxide as a polymerization initiator, a reducing agent, and an appropriate amount of a chelating agent were charged. The polymerization reaction was continued with stirring, and when the polymerization conversion rate reached 80%, the polymerization reaction was terminated by adding 0.1 parts of a 10% aqueous solution of hydroquinone as a polymerization terminator. The residual monomer was then removed at a water temperature of 80°C, yielding an aqueous dispersion of a polymer precursor. Next, a portion of the obtained aqueous dispersion was added to an aqueous solution of magnesium sulfate as a coagulant in an amount of 1.0% by mass relative to the polymer content, and the mixture was stirred to coagulate. The coagulated material was then filtered while being washed with water, and the obtained coagulated material was vacuum dried at 60°C for 12 hours to obtain a polymer. The obtained polymer was dissolved in acetone to a concentration of 10%, and the acetone solution of the polymer and a palladium catalyst (a solution obtained by mixing a 1% palladium acetate acetone solution with an equal weight of ion-exchanged water) were added to an autoclave so that the palladium content relative to the solid content weight was 3,000 ppm. A hydrogenation reaction was carried out at a hydrogen pressure of 3 MPa and a temperature of 55°C for 3 hours. After completion of the hydrogenation reaction, the mixture was poured into a large amount of water to coagulate, followed by filtration and drying to obtain a hydrogenated nitrile-butadiene rubber as polymer A. The iodine value of the obtained polymer A was measured as described above and was found to be 6 mg / 100 mg. This hydrogenated nitrile-butadiene rubber as polymer A was dissolved in NMP to obtain an NMP solution with a polymer A concentration of 8% by mass.

[0106] <Preparation of Conductive Material Dispersion Composition> The NMP solution of polymer A obtained above (concentration: 8% by mass) and suberonitrile (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight: 136) as compound A were mixed in a component ratio of 80% by mass:20% by mass to obtain a conductive material dispersion composition.

[0107] <Preparation of Conductive Material Dispersion Liquid> <<Primary Dispersion Step of Conductive Material Dispersion Liquid>> Carbon nanotubes (specific surface area: 280 m) were used as conductive materials. ２ A conductive material pre-dispersion liquid was obtained by stirring 6.0 parts of a conductive material dispersion composition (NMP solution of a mixture of Polymer A and Compound A, polymer A, and compound A) (average particle size: 1 / g, average diameter: 5-11 nm, average length: 5-30 μm, G / D ratio: 1.1), 1.2 parts (solids equivalent) of the conductive material dispersion composition obtained above (an NMP solution of a mixture of Polymer A and Compound A), and an amount of NMP such that the total amount of the obtained CNT dispersion liquid was 100 parts, using a thin film rotary high-speed mixer ("FILMICS (registered trademark) 40-L type" manufactured by Primix Corporation) at a peripheral speed of 30 m / s for 300 seconds. The conductive material pre-dispersion liquid obtained was evaluated for conductive material dispersibility (initial) as described above. The results are shown in Table 1. <<Secondary Dispersion Step>> After the primary dispersion step, the conductive material pre-dispersion liquid obtained was mixed for 1 hour using a planetary ball mill with zirconia beads having a diameter of 1 mm at 340 rpm to produce a conductive material dispersion liquid with a solids concentration of 7.2%. The dispersion stability of the conductive material was evaluated for the obtained conductive material dispersion liquid according to the above method. The results are shown in Table 1.

[0108] <Production of Positive Electrode> <<Preparation of Slurry Composition for Electrode>> A ternary active material (LiNi) ０．６ Co ０．２ Mn ０．２ O ２ 98.0 parts of PEG-1000 (average particle size: 6 μm), 1.0 part of polyvinylidene fluoride as a binder, 1.0 part of the conductive material dispersion obtained above (solid content equivalent), and NMP were added and mixed using a planetary mixer (60 rpm, 30 minutes) to prepare a positive electrode slurry. The amount of NMP added was adjusted so that the viscosity of the resulting positive electrode slurry (measured using a single cylindrical rotational viscometer in accordance with JIS Z8803:1991, temperature: 25°C, rotation speed: 60 rpm) was within the range of 4000 to 6000 mPa·s. <<Production of Positive Electrode Active Material Layer>> A 15 μm thick aluminum foil was prepared as a current collector. The above slurry was applied to the aluminum foil using a comma coater to a coating weight of 20 mg / cm after drying. 2 The positive electrode was rolled using a roll press to a density of 3.5 g / cm. 3A positive electrode was fabricated, which consisted of a positive electrode active material layer and aluminum foil.

[0109] <Production of negative electrode> A planetary mixer with a disperser was used to prepare a negative electrode active material with a specific surface area of ​​4 m. ２ 100 parts of 1 / g artificial graphite and 1 part of a 1% aqueous solution of carboxymethyl cellulose ("BSH-12" manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a dispersant (solids equivalent) were added, and the solids concentration was adjusted to 55% with ion-exchanged water, followed by mixing at 25°C for 60 minutes. Next, the solids concentration was adjusted to 52% with ion-exchanged water. Mixing was then continued for an additional 15 minutes to obtain a mixed solution. To the above mixed solution, 1.0 part (solids equivalent) of a 40% aqueous solution containing a styrene-butadiene copolymer and ion-exchanged water were added, and the final solids concentration was adjusted to 50%, followed by mixing for an additional 10 minutes. This was then subjected to a degassing treatment to obtain a slurry composition for a negative electrode with good fluidity. The above slurry composition for a negative electrode was coated on a 15 μm-thick copper foil current collector using a comma coater, resulting in a coating weight of 11 mg / cm after drying. 2 The negative electrode blank was then rolled with a roll press to a density of 1.5 g / cm. 3 Thus, a negative electrode having a negative electrode active material layer of the following formula was obtained.

[0110] <Preparation of Separator> A single-layer polypropylene separator (thickness: 25 μm, porosity: 55%) was prepared.

[0111] <Cell Fabrication> An aluminum packaging material was prepared as the battery packaging. The positive electrode manufactured as described above was cut into a 4 cm x 4 cm square and placed so that the surface on the current collector side was in contact with the aluminum packaging material. Next, a square separator punched to 5 cm x 5 cm was placed on the surface of the positive electrode composite layer of the positive electrode. Furthermore, the negative electrode was cut into a 4.2 cm x 4.2 cm square and placed on the separator so that the surface on the negative electrode composite layer side faced the separator. Then, LiPF 5 with a concentration of 1.0 M was used as the electrolyte. ６A solution (a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3 / 7, with 2% by volume of vinylene carbonate as an additive) was filled into the battery. Furthermore, in order to seal the opening of the aluminum packaging, the exterior of the aluminum packaging was closed by heat sealing at 150°C, thereby producing a laminate cell type lithium ion secondary battery. The IV characteristics of the lithium ion secondary battery obtained by the above-mentioned method were evaluated. The results are shown in Table 1.

[0112] (Example 2) In <Preparation of a conductive material dispersion composition>, various operations, measurements, and evaluations were carried out in the same manner as in Example 1, except that succinonitrile (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 80) was used as compound A. The results are shown in Table 1.

[0113] (Example 3) In <Preparation of conductive material dispersion composition>, various operations, measurements, and evaluations were carried out in the same manner as in Example 1, except that 1,3,6-hexanetricarbonitrile (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 161) was used as compound A. The results are shown in Table 1.

[0114] (Example 4) In <Preparation of Polymer A>, the amount of t-dodecyl mercaptan used as a chain transfer agent was changed to 0.25 parts, and the same operations, measurements, and evaluations as in Example 1 were carried out. The results are shown in Table 1.

[0115] (Example 5) In <Preparation of Polymer A>, the amount of t-dodecyl mercaptan used as a chain transfer agent was changed to 8.5 parts, and the same operations, measurements, and evaluations were carried out as in Example 1. The results are shown in Table 1.

[0116] Example 6 The same operations, measurements, and evaluations as in Example 1 were carried out, except that the <Preparation of Polymer A> was changed as follows. The results are shown in Table 1. <Preparation of Polymer A> A reactor was charged with 200 parts of ion-exchanged water, 25 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate, 34 parts of acrylonitrile as a nitrile group-containing monomer, 3 parts of methacrylic acid as a hydrophilic group-containing monomer, and 1.70 parts of t-dodecyl mercaptan as a chain transfer agent, in that order. Next, the internal gas was purged with nitrogen three times, and then 63 parts of 1,3-butadiene as a conjugated diene monomer was charged. The reactor was then maintained at 10°C, and 0.03 parts of cumene hydroperoxide as a polymerization initiator, an appropriate amount of a reducing agent, and a chelating agent were charged. The polymerization reaction was continued with stirring, and when the polymerization conversion reached 80%, the polymerization reaction was terminated by adding 0.1 parts of a 10% aqueous solution of hydroquinone as a polymerization terminator. Next, residual monomers were removed at a water temperature of 80°C to obtain an aqueous dispersion of a polymer precursor. The aqueous dispersion and a palladium catalyst (a solution obtained by mixing a 1% palladium acetate acetone solution with an equal weight of ion-exchanged water) were added to an autoclave so that the palladium content relative to the solids weight contained in the obtained aqueous dispersion of the polymer precursor was 3,000 ppm, and a hydrogenation reaction was carried out at a hydrogen pressure of 3 MPa and a temperature of 55°C for 3 hours to obtain an aqueous dispersion of a polymer (hydrogenated nitrile rubber). The iodine value of the obtained polymer A was measured as described above and found to be 20 mg / 100 mg. A 2.5% aqueous KOH solution was added to the aqueous dispersion of the polymer obtained as described above, and the pH was adjusted to 9.5. 200 parts of N-methylpyrrolidone was added to 100 parts of the pH-adjusted aqueous dispersion of the polymer, and all water and residual monomers were evaporated under reduced pressure. The N-methylpyrrolidone was then evaporated to a concentration of 8% by mass to obtain an NMP solution of polymer A.

[0117] (Example 7) In <Preparation of a conductive material dispersion composition>, the NMP solution of polymer A obtained above (concentration 8% by mass) and suberonitrile (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 136) as compound A were mixed in a component ratio of 50% by mass:50% by mass to obtain a conductive material dispersion composition. Except for this, the same operations, measurements, and evaluations as in Example 1 were performed. The results are shown in Table 1.

[0118] (Example 8) In <Preparation of a conductive material dispersion composition>, the NMP solution of polymer A obtained above (concentration 8% by mass) and suberonitrile (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 136) as compound A were mixed in a component ratio of 90% by mass to 10% by mass to obtain a conductive material dispersion composition. Except for this, the same operations, measurements, and evaluations as in Example 1 were carried out. The results are shown in Table 1.

[0119] (Example 9) In <Preparation of a conductive material dispersion composition>, the same operations, measurements, and evaluations as in Example 1 were carried out, except that adipic acid (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 146) was used as compound A. The results are shown in Table 2.

[0120] (Example 10) In <Preparation of a conductive material dispersion composition>, the same operations, measurements, and evaluations as in Example 1 were carried out, except that cyanoacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 85) was used as compound A. The results are shown in Table 2.

[0121] (Example 11) In <Preparation of a conductive material dispersion composition>, the same operations, measurements, and evaluations as in Example 1 were carried out, except that 4-phenylbutyronitrile (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 145) was used as compound A. The results are shown in Table 2.

[0122] (Example 12) In <Preparation of conductive material dispersion composition>, an NMP solution of polymer A (concentration 8% by mass) and suberonitrile as compound A were mixed in a component ratio of 40% by mass to 60% by mass to obtain a conductive material dispersion composition. Except for this, various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0123] (Example 13) In <Preparation of conductive material dispersion composition>, an NMP solution of polymer A (concentration 8% by mass) and suberonitrile as compound A were mixed in a component ratio of 20% by mass to 80% by mass to obtain a conductive material dispersion composition. Except for this, various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 2.

[0124] Example 14 Various operations, measurements, and evaluations were carried out in the same manner as in Example 1, except that polyallyl cyanide (a polymer composed of allyl cyanide units) synthesized according to the following procedure was used as Compound A. The results are shown in Table 2. <Preparation of Compound A> 100 parts by mass of allyl cyanide and 970 parts by mass of tetrahydrofuran were placed in a reactor in a glove box under a nitrogen atmosphere, and the solution was cooled to -20°C. When the internal temperature reached -20°C, 0.56 parts by mass of a 1.5 mol / L n-butyllithium-hexane solution was added and the reaction was carried out. Three hours after the start of the reaction, methanol was added to stop the reaction, and the reaction solution was added dropwise to methanol, and a precipitate was obtained by precipitation purification. The obtained precipitate was vacuum dried at 40°C for 6 hours to obtain Compound A. The molecular weight of the obtained Compound A was measured by GPC in the same manner as for Polymer A, and the weight average molecular weight was found to be 2,000.

[0125] (Comparative Example 1) In <Preparation of a conductive material dispersion composition>, various operations, measurements, and evaluations were carried out in the same manner as in Example 1, except that propionitrile (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 55), which is a compound not having two or more predetermined functional groups, was used instead of compound A. The results are shown in Table 1.

[0126] (Comparative Example 2) No component corresponding to polymer A was blended, and 1.2 parts of suberonitrile, which is compound A, was blended as a conductive material dispersion composition in the primary dispersion step of the conductive material dispersion. Except for this, various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0127] (Comparative Example 3) No component corresponding to Compound A was blended, and 1.2 parts in terms of solid content of an NMP solution of Polymer A (solid content concentration: 8% by mass) was blended as a conductive material dispersion composition in the primary dispersion step of the conductive material dispersion. Except for this, various operations, measurements, and evaluations were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0128] In Table 1, "AN" represents an acrylonitrile unit, "BD" represents a 1,3-butadiene unit, "H-BD" represents a 1,3-butadiene hydride unit, "MAA" represents a methacrylic acid unit, and "CNT" represents a carbon nanotube.

[0129]

[0130]

[0131] The results shown in Tables 1 and 2 show that in Examples 1 to 14, which used a dispersion composition containing compound A having two or more functional groups selected from the group consisting of cyano groups, carboxyl groups, and phenyl groups, and polymer A, the conductive material dispersions had excellent dispersibility and the IV resistance of the electrochemical elements was low. On the other hand, in Comparative Example 1, in which propionitrile, a compound that does not satisfy the conditions, was blended instead of the specified compound A, Comparative Example 2, in which a component corresponding to polymer A was not blended into the dispersion composition, and Comparative Example 3, in which a component corresponding to compound A was not blended into the dispersion composition, the conductive material dispersions had poor dispersibility and the IV resistance of the electrochemical elements was high.

[0132] According to the present invention, it is possible to provide a conductive material dispersion composition for electrochemical elements that can improve the dispersibility of a conductive material for electrochemical elements. Also, according to the present invention, it is possible to provide a conductive material dispersion liquid for electrochemical elements that has excellent dispersibility. Furthermore, according to the present invention, it is possible to provide a slurry composition for electrochemical element electrodes that includes the above-mentioned conductive material dispersion composition for electrochemical elements. And according to the present invention, it is possible to provide an electrode for electrochemical elements formed using the above-mentioned slurry composition for electrochemical element electrodes, and an electrochemical element including such an electrode.

Claims

1. A conductive material dispersion composition for electrochemical elements, comprising a compound A having two or more functional groups and a polymer A, wherein the compound A having two or more functional groups has two or more functional groups selected from the group consisting of a cyano group, a carboxyl group, and a phenyl group, and the two or more functional groups may be the same or different.

2. The conductive material dispersion composition for electrochemical elements according to claim 1, wherein the polymer A contains a linear alkylene structural unit having 4 or more carbon atoms and a nitrile-containing monomer unit.

3. The conductive material dispersion composition for electrochemical elements according to claim 1 or 2, wherein the compound A having two or more functional groups has a molecular weight of 70 or more and 4,000 or less.

4. The conductive material dispersion composition for electrochemical elements according to claim 1 or 2, wherein the compound A having two or more functional groups has a molecular weight of 70 or more and 8,000 or less.

5. The conductive material dispersion composition for electrochemical elements according to claim 1 or 2, wherein the compound A having two or more functional groups has a molecular weight of 85 or more and 8,000 or less.

6. The conductive material dispersion composition for electrochemical elements according to claim 1 or 2, wherein the compound A having two or more functional groups has a molecular weight of 85 or more and 4,000 or less.

7. The conductive material dispersion composition for electrochemical elements according to claim 1 or 2, wherein the compound A having two or more functional groups has a molecular weight of 85 or more and 3,000 or less.

8. The conductive material dispersion composition for electrochemical elements according to any one of claims 1 to 7, wherein the weight average molecular weight of the polymer A is 3,000 or more and 500,000 or less.

9. The conductive material dispersion composition for electrochemical elements according to any one of claims 1 to 7, wherein the weight average molecular weight of the polymer A is 8,000 or more and 400,000 or less.

10. The conductive material dispersion composition for electrochemical elements according to any one of claims 1 to 7, wherein the weight average molecular weight of the polymer A is 15,000 or more and 300,000 or less.

11. A conductive material dispersion composition for electrochemical elements according to any one of claims 1 to 10, wherein the blending ratio of said compound A is in the range of 10 parts by mass or more and 50 parts by mass or less, where the total mass of said polymer A and said compound A having two or more functional groups is 100 parts by mass.

12. A conductive material dispersion composition for electrochemical elements according to any one of claims 1 to 10, wherein the blending ratio of said compound A is in the range of 18 parts by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the total mass of said polymer A and said compound A having two or more functional groups.

13. A conductive material dispersion composition for electrochemical elements according to any one of claims 1 to 10, wherein the blending ratio of compound A is in the range of 18 parts by mass or more and 32 parts by mass or less, relative to 100 parts by mass of the total mass of polymer A and compound A having two or more functional groups.

14. A conductive material dispersion for electrochemical elements, comprising a conductive carbon material as a conductive material, a solvent, and the conductive material dispersion composition for electrochemical elements according to any one of claims 1 to 13.

15. The conductive carbon material has a BET specific surface area of ​​150 m ２ The conductive material dispersion liquid for an electrochemical element according to claim 14, wherein the dispersion liquid has a G / D ratio of 0.4 or more as determined by Raman spectroscopy and a G / D ratio of 0.4 or more as determined by Raman spectroscopy.

16. A slurry composition for an electrochemical element electrode, comprising a conductive carbon material as a conductive material, an electrode active material, the conductive material dispersion composition for an electrochemical element according to any one of claims 1 to 13, and a solvent.

17. An electrode for an electrochemical element, comprising an electrode mixture layer formed on a current collector foil and made of a dried product of the slurry composition for an electrochemical element electrode according to claim 16.

18. An electrochemical device comprising the electrode for an electrochemical device according to claim 17.

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