Carbon nanotube dispersion paste, mixture paste for lithium ion secondary battery, electrode layer for nonaqueous electrolyte lithium ion secondary battery, electrode for nonaqueous electrolyte lithium ion secondary battery, and nonaqueous electrolyte lithium ion secondary battery

Abstract

The present invention addresses the problem of providing: a carbon nanotube dispersion paste which has excellent dispersibility of carbon nanotubes, low initial viscosity during production, and excellent storage stability at high temperature (for example, 45°C or higher, particularly 50°C or higher); an electrode layer for a nonaqueous electrolyte lithium ion secondary battery which uses the mixture paste for a lithium ion secondary battery; an electrode for a nonaqueous electrolyte lithium ion secondary battery which uses the electrode layer for a nonaqueous electrolyte lithium ion secondary battery; and a nonaqueous electrolyte lithium ion secondary battery which is provided with at least the electrode for a nonaqueous electrolyte lithium ion secondary battery. As a means for solving the problem, provided is a carbon nanotube dispersion paste containing a dispersion resin (A), carbon nanotubes (B), and N-methyl-2-pyrrolidone (C), the dispersion term deltaD of the Hansen solubility parameter of the dispersion resin (A) being 16.35 or more, and Ra based on the Hansen solubility parameter of the dispersion resin (A) with respect to N-methyl-2-pyrrolidone (C) being 10.5 or less.

Description

Carbon nanotube dispersion paste, composite paste for lithium-ion secondary batteries, electrode layer for non-aqueous electrolyte lithium-ion secondary batteries, electrode for non-aqueous electrolyte lithium-ion secondary batteries, and non-aqueous electrolyte lithium-ion secondary battery

[0001] The present invention relates to a carbon nanotube dispersion paste, a composite paste for lithium-ion secondary batteries, an electrode layer for a non-aqueous electrolyte lithium-ion secondary battery, an electrode for a non-aqueous electrolyte lithium-ion secondary battery, and a non-aqueous electrolyte lithium-ion secondary battery. In particular, the present invention relates to a carbon nanotube dispersion paste that is excellent in initial dispersibility, initial viscosity and storage stability at high temperatures, a composite paste for lithium-ion secondary batteries containing the carbon nanotube dispersion paste, an electrode layer for a non-aqueous electrolyte lithium-ion secondary battery using the composite paste for lithium-ion secondary batteries, an electrode for a non-aqueous electrolyte lithium-ion secondary battery using the electrode layer for a non-aqueous electrolyte lithium-ion secondary battery, and a non-aqueous electrolyte lithium-ion secondary battery comprising at least the electrode for a non-aqueous electrolyte lithium-ion secondary battery.

[0002] Carbon pigments such as carbon nanotubes and carbon black are widely incorporated into materials such as paints, coatings, sealants, filters, films, sheets, inks, cosmetic materials, magnet modifiers, encapsulants, device components, electronic equipment components, printed circuit boards, battery materials, and resin molded products, providing functions such as electrostatic coating properties, conductivity, electromagnetic shielding properties, and antistatic properties. When forming materials containing such carbon pigments, it is important to disperse the carbon pigment in the solvent at a high concentration and uniformly so that it can be easily applied, in order to streamline the production process. For this reason, there is a demand for carbon pigment dispersion pastes with excellent properties such as pigment dispersibility, storage stability, conductivity, coating properties, and finish. In designing carbon pigment dispersion pastes, it is important that components such as dispersion resins do not adversely affect the conductivity of the final product itself, such as the coating film, that the amount of solvent and dispersion resin used is reduced, that the energy used during drying can be reduced, and that the carbon pigment paste is highly concentrated and uniformly dispersed.

[0003] For example, Patent Documents 1 to 4 describe carbon nanotube dispersions containing a dispersant, carbon nanotubes, and a solvent. However, these carbon nanotube dispersions have shortcomings, such as poor dispersibility and inability to achieve uniform dispersion, high initial viscosity during manufacturing, and poor storage stability at high temperatures, and improvements have been needed.

[0004] Japanese Patent Publication No. 2019-192537, Japanese Patent Publication No. 2023-29200, Japanese Patent Publication No. 2024-000897, Japanese Patent Publication No. 2011-70908

[0005] One of the problems that the present invention aims to solve is to provide a carbon nanotube dispersion paste containing a dispersion resin (A), a carbon nanotube (B), and N-methyl-2-pyrrolidone (C), wherein the dispersion resin (A) has a Hansen solubility parameter δD of 16.35 or higher, and the Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C) based on the Hansen solubility parameter is 10.5 or lower. Furthermore, the present invention aims to provide a non-aqueous electrolyte lithium-ion secondary battery comprising at least an electrode layer for a non-aqueous electrolyte lithium-ion secondary battery using the lithium-ion electrolyte paste, an electrode for a non-aqueous electrolyte lithium-ion secondary battery using the non-aqueous electrolyte lithium-ion secondary battery electrode layer, and an electrode for a non-aqueous electrolyte lithium-ion secondary battery. One of the problems that the present invention aims to solve is to provide a carbon nanotube dispersion paste that has excellent dispersibility of carbon nanotubes, low initial viscosity during manufacturing, and excellent storage stability at high temperatures (e.g., 45°C or higher, especially 50°C or higher), and further to provide a non-aqueous electrolyte lithium-ion secondary battery comprising at least an electrode layer for a non-aqueous electrolyte lithium-ion secondary battery using the composite paste for lithium-ion secondary batteries, an electrode for a non-aqueous electrolyte lithium-ion secondary battery using the electrode layer for a non-aqueous electrolyte lithium-ion secondary battery, and an electrode for a non-aqueous electrolyte lithium-ion secondary battery.

[0006] As a result of diligent research to solve the above problems, the present inventors have found that the above problems can be solved by a carbon nanotube dispersion paste containing a dispersion resin (A), a carbon nanotube (B), and N-methyl-2-pyrrolidone (C), wherein the dispersion resin (A) has a Hansen solubility parameter δD of 16.35 or higher, and the Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C) based on the Hansen solubility parameter is 10.5 or lower; a composite paste for lithium-ion secondary batteries containing the carbon nanotube dispersion paste; a battery electrode in which a composite layer formed from the composite paste for lithium-ion secondary batteries is formed on a current collector; and a battery equipped with the battery electrode, and have thus completed the present invention.

[0007] In other words, the present invention relates to the following carbon nanotube dispersion paste, composite paste for lithium-ion secondary batteries, electrode layer for non-aqueous electrolyte lithium-ion secondary batteries, electrode for non-aqueous electrolyte lithium-ion secondary batteries, and non-aqueous electrolyte lithium-ion secondary batteries.

[0008] [Item 1] A carbon nanotube dispersion paste containing a dispersion resin (A), a carbon nanotube (B), and N-methyl-2-pyrrolidone (C), wherein the dispersion term δD of the Hansen solubility parameter of the dispersion resin (A) is 16.35 or higher, and the Ra of the dispersion resin (A) based on the Hansen solubility parameter for N-methyl-2-pyrrolidone (C) is 10.5 or lower. [Item 2] The carbon nanotube dispersion paste according to Item 1, wherein the dispersion term δD of the Hansen solubility parameter of the dispersion resin (A) is in the range of 16.5 to 16.9. [Item 3] The carbon nanotube dispersion paste according to Item 1 or 2, wherein the Ra of the dispersion resin (A) based on the Hansen solubility parameter for N-methyl-2-pyrrolidone (C) is in the range of 7.3 to 10.2. [Item 4] The carbon nanotube dispersion paste according to any one of items 1 to 3, wherein the dispersion resin (A) has at least one polar functional group selected from the group consisting of amide groups, imide groups, hydroxyl groups, carboxyl groups, sulfonic acid groups, phosphate groups, amino groups, and cyano groups, and the concentration of the polar functional group is 0.1 mmol / g or more and 8.5 mmol / g or less. [Item 5] The carbon nanotube dispersion paste according to any one of items 1 to 4, wherein the water content of the N-methyl-2-pyrrolidone (C) is 10,000 ppm or less. [Item 6] The carbon nanotube dispersion paste according to any one of items 1 to 5, which contains a polyvinylidene fluoride resin (D). [Item 7] The carbon nanotube dispersion paste according to any one of items 1 to 6, which contains a highly polar, low molecular weight component (E). [Item 8] The carbon nanotube dispersion paste according to any one of items 1 to 7, which has a water content of 10,000 ppm or less. [Item 9] A composite paste for lithium-ion secondary batteries comprising a dispersion resin (A), carbon nanotubes (B), N-methyl-2-pyrrolidone (C), polyvinylidene fluoride resin (D), and electrode active material (F), wherein the dispersion term δD of the Hansen solubility parameter of the dispersion resin (A) is 16.35 or higher, and the Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C) based on the Hansen solubility parameter is 10.5 or lower.[Item 10] An electrode layer for a non-aqueous electrolyte lithium-ion secondary battery, obtained by coating a current collector with the lithium-ion secondary battery composite paste described in Item 9. [Item 11] An electrode for a non-aqueous electrolyte lithium-ion secondary battery, wherein an electrode insulating portion is provided at the end or upper layer of the electrode layer for a non-aqueous electrolyte lithium-ion secondary battery described in Item 10. [Item 12] A non-aqueous electrolyte lithium-ion secondary battery comprising at least a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator, each having the electrode layer for a non-aqueous electrolyte lithium-ion secondary battery described in Item 11.

[0009] The present invention provides a carbon nanotube dispersion paste containing a dispersion resin (A), carbon nanotubes (B), and N-methyl-2-pyrrolidone (C), wherein the dispersion resin (A) has a Hansen solubility parameter δD of 16.35 or higher, and the Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C) based on the Hansen solubility parameter is 10.5 or lower. Furthermore, the present invention provides a non-aqueous electrolyte lithium-ion secondary battery comprising at least an electrode layer for a non-aqueous electrolyte lithium-ion secondary battery using the lithium-ion electrolyte paste, an electrode for a non-aqueous electrolyte lithium-ion secondary battery using the non-aqueous electrolyte lithium-ion secondary battery electrode layer, and an electrode for a non-aqueous electrolyte lithium-ion secondary battery. The present invention provides a carbon nanotube dispersion paste that exhibits excellent dispersibility of carbon nanotubes, low initial viscosity during manufacturing, and excellent storage stability at high temperatures (e.g., 45°C or higher, particularly 50°C or higher). Furthermore, the present invention provides a non-aqueous electrolyte lithium-ion secondary battery comprising at least an electrode layer for a non-aqueous electrolyte lithium-ion secondary battery using the lithium-ion electrolyte composite paste, an electrode for a non-aqueous electrolyte lithium-ion secondary battery using the non-aqueous electrolyte lithium-ion secondary battery electrode layer, and an electrode for a non-aqueous electrolyte lithium-ion secondary battery.

[0010] The embodiments for carrying out the present invention will be described in detail below. It should be understood that the present invention is not limited to the following embodiments, but also includes various modifications that do not alter the essence of the invention. In this specification, carbon nanotubes may be referred to as "CNTs".

[0011] [Carbon Nanotube Dispersion Paste] The carbon nanotube dispersion paste of the present invention is a carbon nanotube dispersion paste containing a dispersion resin (A), carbon nanotubes (B), and N-methyl-2-pyrrolidone (C), wherein the dispersion resin (A) has a dispersion term δD of the Hansen solubility parameter of 16.35 or higher, and the Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C) based on the Hansen solubility parameter is 10.5 or lower. The dispersion resin (A) may also have a dispersion term δD of the Hansen solubility parameter in the range of 16.5 to 16.9. The dispersion resin (A) may also have a Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C) based on the Hansen solubility parameter in the range of 7.3 to 10.2. The dispersion resin (A) may have at least one polar functional group selected from the group consisting of amide groups, imide groups, hydroxyl groups, carboxyl groups, sulfonic acid groups, phosphoric acid groups, amino groups, and cyano groups, and the concentration of the polar functional group may be 0.1 mmol / g or more and 8.5 mmol / g or less. The water content of the N-methyl-2-pyrrolidone (C) may be 10,000 ppm or less. The carbon nanotube dispersion paste of the present invention may contain a polyvinylidene fluoride resin (D). The carbon nanotube dispersion paste of the present invention may contain a highly polar, low molecular weight component (D). The carbon nanotube dispersion paste of the present invention may have a water content of 10,000 ppm or less. The details will be described below.

[0012] <Dispersion Resin (A)> The carbon nanotube dispersion paste of the present invention contains dispersion resin (A). Dispersion resin (A) has a dispersion term δD of the Hansen solubility parameter of 16.35 or higher, and Ra based on the Hansen solubility parameter of dispersion resin (A) for N-methyl-2-pyrrolidone (C) is 10.5 or lower. Dispersion resin (A) may have a dispersion term δD of the Hansen solubility parameter in the range of 16.5 to 16.9. Dispersion resin (A) may have Ra based on the Hansen solubility parameter for N-methyl-2-pyrrolidone (C) in the range of 7.3 to 10.2. Dispersion resin (A) has at least one polar functional group selected from the group consisting of amide group, imide group, hydroxyl group, carboxyl group, sulfonic acid group, phosphate group, amino group and cyano group, and the concentration of the polar functional group may be 0.1 mmol / g to 8.5 mmol / g.

[0013] (Resin) The resin constituting the dispersion resin (A) is not particularly limited as long as it is a resin other than the polyvinylidene fluoride resin (D) described later. For example, one or more resins selected from the group consisting of acrylic resins (acrylic resins), polyester resins, epoxy resins, polyether resins, alkyd resins, polyurethane resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyvinylpyrrolidone resins, polyvinyl acetate resins, silicone resins, polycarbonate resins, chlorine resins, and composite resins thereof can be cited. In this invention, the acrylic resin includes methacrylic resin. In this invention, "(poly)X resin" means that in addition resins, the main monomer is X, and in condensation resins, it means a resin in which the bond produced by the main condensation reaction is X. In this invention, the resin constituting the dispersion resin (A) is preferably a resin having an alkyl group and / or heterocycle with 12 or more carbon atoms in its molecule.

[0014] The alkyl group having 12 or more carbon atoms that may be included in the dispersion resin (A) is not particularly limited. Preferably, it is an alkyl group having 16 or more carbon atoms, more preferably an alkyl group having 18 or more carbon atoms, and even more preferably an alkyl group having 19 or more carbon atoms. The upper limit of the number of carbon atoms in the alkyl group is, for example, 30 or less, preferably 26 or less, more preferably 24 or less, and even more preferably 23 or less. The alkyl group having 12 or more carbon atoms may be a linear alkyl group or a branched alkyl group. A linear alkyl group is preferred. When the dispersion resin (A) is a resin having an alkyl group having 12 or more carbon atoms, it becomes a resin with relatively bulky side chains, and it is presumed that the carbon nanotube dispersibility and storage stability are improved due to steric repulsion.

[0015] The method for introducing an alkyl group having 12 or more carbon atoms into the dispersed resin (A) is not particularly limited. Examples include (co)polymerization reactions of monomers containing alkyl groups having 12 or more carbon atoms, modification reactions of polymers (resins), and / or addition reactions. Examples of polymerizable monomers containing alkyl groups having 12 or more carbon atoms include one or more selected from the group consisting of lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, behenyl (meth)acrylate, lauryl (meth)acrylamide, stearyl (meth)acrylamide, behenyl (meth)acrylamide, etc.

[0016] The content of an alkyl group having 12 or more carbon atoms in the dispersion resin (A) is not particularly limited. Based on 100% by mass of all the monomers constituting the dispersion resin (A), the polymerizable monomer containing an alkyl group having 12 or more carbon atoms is, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, particularly preferably 40% by mass or more, and even more particularly preferably 50% by mass or more, and can be, for example, 100% by mass or less, preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less. Further, in the case of reacting a compound having an alkyl group having 12 or more carbon atoms with the resin, the mass ratio of the compound to the total mass of the resin and the compound is, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 20% by mass or more, still more preferably 30% by mass or more, and can be less than 100% by mass, preferably 90% by mass or less, more preferably 80% by mass or less, still more preferably 70% by mass or less.

[0017] Examples of the heterocyclic ring that may be contained in the dispersion resin (A) include a ring containing one or more atoms other than carbon, such as oxygen, nitrogen, sulfur, etc., in addition to carbon atoms as the atoms constituting the cyclic structure. The number of cyclic structures contained in the heterocyclic ring is preferably one or two, and more preferably one. As the atom other than carbon constituting the ring, oxygen and / or nitrogen is preferable, and nitrogen is more preferable. When the dispersion resin (A) is a resin having a heterocyclic ring, it is presumed that polarization easily occurs within the heterocyclic ring due to the atoms other than carbon atoms in the heterocyclic ring, and thereby the dispersion resin (A) strongly acts on the carbon nanotubes. Further, it becomes a resin having a relatively bulky side chain, and it is considered that the carbon nanotube dispersibility and storage stability are improved by steric repulsion.

[0018] The method for introducing a heterocyclic ring into the dispersion resin (A) is not particularly limited. For example, (co)polymerization reaction of a monomer containing a heterocyclic ring, modification reaction of a polymer (resin), and / or addition reaction, etc. may be mentioned. Examples of the polymerizable monomer containing a heterocyclic ring include one or more selected from the group consisting of 2- or 4-vinylpyridine, N-vinylimidazole, N-vinylpyrrole, N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-1,3-oxazine-2-one, N-vinyl-3,5-morpholinedione, glycidyl (meth)acrylate, maleic anhydride, itaconic anhydride, etc.

[0019] The content of the heterocyclic ring in the dispersion resin (A) is not particularly limited. Based on 100% by mass of all the monomers constituting the dispersion resin (A), the polymerizable monomer containing a heterocyclic ring can be, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, and can be 100% by mass or less, preferably 99% by mass or less, more preferably 95% by mass or less. Also, in the case of reacting a compound having a heterocyclic ring with the resin, as the mass ratio of the compound to the total mass of the resin and the mass of the compound, it can be, for example, 1% by mass or more, preferably 10% by mass or more, more preferably 30% by mass or more, still more preferably 50% by mass or more, and can be less than 100% by mass, preferably 99% by mass or less, more preferably 95% by mass or less.

[0020] As the dispersion resin (A), from the viewpoints of carbon nanotube dispersibility, high-temperature storage stability, finishability, etc., the following formula (1): CR １ , １ , ２ , １ , ４ , ３ , ４ , １ , ２ , ２ , ３ ,

[0020] R ２ =CR ３ R ４ ...(1) (In formula (1), R １ ~R ４ may be the same or different from each other, and is a hydrogen atom or a monovalent organic group. Also, R １ and R ２ may be bonded to each other to form a ring, and R １ or R ２ and, R ３or R ４ It is preferable to contain a vinyl (co)polymer (A1) obtained by polymerizing or copolymerizing a monomer component containing a polymerizable unsaturated group-containing monomer represented by ). In this invention, the (co)polymer includes both polymers obtained by polymerizing one type of monomer and copolymers obtained by copolymerizing two or more types of monomers.

[0021] The vinyl (co)polymer (A1) contains the following in its structure: formula (2): -CH ２ -CR ５ (-X)-...(2) (In formula (2), R ５ It is preferable that the material contains a structural unit represented by ) where is a hydrogen or methyl group, and X is an active hydrogen-containing group. Examples of vinyl (co)polymer (A1) include one or more selected from the group consisting of hydroxyl group-containing vinyl (co)polymer, carboxyl group-containing vinyl (co)polymer, amide group-containing vinyl (co)polymer, sulfonic acid group-containing vinyl (co)polymer, phosphate group-containing vinyl (co)polymer, pyrrolidone group-containing vinyl (co)polymer, etc.

[0022] Examples of hydroxyl group-containing vinyl (co)polymers include one or more selected from the group consisting of polyhydroxyalkyl (meth)acrylate (such as polyhydroxyethyl (meth)acrylate), polyvinyl alcohol, vinyl alcohol-fatty acid vinyl copolymer, vinyl alcohol-ethylene copolymer, vinyl alcohol-(N-vinylformamide) copolymer, and copolymers of hydroxyalkyl (meth)acrylate and other polymerizable unsaturated monomers. The vinyl alcohol structural units in the (co)polymer can be obtained by polymerizing the monomer component containing fatty acid vinyl and then hydrolyzing it.

[0023] Examples of carboxyl group-containing vinyl (co)polymers include one or more selected from the group consisting of polymers of (meth)acrylic acid and copolymers of (meth)acrylic acid and other polymerizable unsaturated monomers.

[0024] Examples of amide group-containing vinyl (co)polymers include one or more selected from the group consisting of (meth)acrylamide polymers and (meth)acrylamide derivatives (polymers such as 3-(meth)acrylamidopropyltrimethylammonium chloride, copolymers of (meth)acrylamide and other polymerizable unsaturated monomers, etc.).

[0025] Examples of sulfonic acid group-containing vinyl (co)polymers include one or more selected from the group consisting of polymers such as allyl sulfonic acid or styrene sulfonic acid, and copolymers of allyl sulfonic acid and / or styrene sulfonic acid with other polymerizable unsaturated monomers.

[0026] Examples of phosphate-containing vinyl (co)polymers include one or more selected from the group consisting of polymers of (meth)acryloyloxyalkyl acid phosphates, copolymers of (meth)acryloyloxyalkyl acid phosphates and other polymerizable unsaturated monomers, etc.

[0027] The vinyl (co)polymer (A1) may, in addition to the structural unit represented by formula (2), optionally contain structural units derived from copolymerizable polymerizable unsaturated group-containing monomers. Examples of copolymerizable polymerizable unsaturated group-containing monomers include vinyl carboxylate monomers such as vinyl formate, vinyl acetate, vinyl propionate, isopropenyl acetate, vinyl valerate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl versaticate, and vinyl pivalate; olefins such as ethylene, propylene, and butylene; aromatic vinyls such as styrene and α-methylstyrene (monomers that do not contain two or more aromatic rings are particularly preferred, with styrene being the most preferred); methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and methyl (meth)acrylate. Examples include ethylenically unsaturated carboxylate alkyl monomers such as 2-ethylhexyl acid, dimethyl fumarate, dimethyl maleate, diethyl maleate, and diisopropyl itaconate; vinyl ether monomers such as methyl vinyl ether, n-propyl vinyl ether, isobutyl vinyl ether, and dodecyl vinyl ether; vinyl halogenated monomers or vinylidene monomers such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; quaternary ammonium group-containing monomers; and one or more selected from the group consisting of vinyltrimethoxysilane, N-vinylformamide, and N-vinyl-2-pyrrolidone.

[0028] (Weight-average molecular weight) The weight-average molecular weight of the dispersion resin (A) is not particularly limited. For example, it can be 500 or more, preferably 1,000 or more, more preferably 2,000 or more, even more preferably 7,000 or more, and even more preferably 20,000 or more. For example, it can be 2,000,000 or less, preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 100,000 or less. For example, 500 or more and 2,000,000 or less, for example, 500 or more and 1,000,000 or less, for example, 500 or more and 500,000 or less, for example, 500 or more and 100,000 or less, for example, 1,000 or more and 2,000,000 or less, for example, 1,000 or more and 1,000,000 or less, for example, 1,000 or more and 500,000 It can be expressed as 00 or less, for example 1,000 to 100,000, for example 2,000 to 2,000,000, for example 2,000 to 1,000,000, for example 2,000 to 500,000, for example 2,000 to 100,000, for example 7,000 to 2,000,000, for example 7,000 to 1,000,000, for example 7,000 to 500,000, for example 7,000 to 100,000, for example 20,000 to 2,000,000, for example 20,000 to 1,000,000, for example 20,000 to 500,000, for example 20,000 to 100,000.

[0029] Unless otherwise specified, the weight-average molecular weight can be obtained by converting the retention time (retention volume) measured using gel permulation chromatography (GPC) to the molecular weight of polystyrene using the retention time (retention volume) of standard polystyrene with a known molecular weight measured under the same conditions. Specifically, the weight-average molecular weight can be obtained by using "HLC8120GPC" (product name, manufactured by Tosoh Corporation) as the gel permulation chromatograph, and four columns: "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL", and "TSKgel G-2000HXL" (product names, all manufactured by Tosoh Corporation), under the conditions of tetrahydrofuran mobile phase, measurement temperature of 40°C, flow rate of 1 mL / min, and detector RI.

[0030] (Polymerization Method) The method for synthesizing the dispersion resin (A) is not particularly limited. In the case of addition-type resins, it can be polymerized and synthesized by a known addition polymerization reaction, and in the case of condensation-type resins, it can be polymerized and synthesized by a known condensation polymerization reaction. Among these, when vinyl (co)polymer (A1) is used as the dispersion resin (A), the method for synthesizing vinyl (co)polymer (A1) (polymerization method) is not particularly limited. Methods known in themselves can be used as the polymerization method for vinyl (co)polymer. For example, solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc. can be used. In the present invention, solution polymerization is preferred. Solution polymerization may be continuous polymerization or batch polymerization. The monomer components may be charged all at once, charged in parts, or added continuously or intermittently. The polymerization reaction temperature is not particularly limited, but for example, it can be in the range of 30°C to 200°C.

[0031] The polymerization initiator used in the solution polymerization of vinyl (co)polymer (A1) is not particularly limited. For example, one or more selected from the group consisting of azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, azobis(4-methoxy-2,4-dimethylvaleronitrile), and azobis-4-methoxyvaleronitrile; peroxides such as acetyl peroxide, benzoyl peroxide, lauroyl peroxide, acetylcyclohexylsulfonyl peroxide, and 2,4,4-trimethylpentyl-2-peroxyphenoxyacetate; peroxycarbonate compounds such as diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, and diethoxyethyl peroxydicarbonate; and perester compounds such as t-butyl peroxyneodecanate, α-cumyl peroxyneodecanate, and t-butyl peroxyneodecanate.

[0032] The dispersed resin (A) can be converted into a solid or a resin solution in any solvent by desolvation and / or solvent replacement after the synthesis is complete. Desolvation can be carried out by heating under atmospheric pressure, or by desolvation under reduced pressure. Solvent replacement can be carried out by adding the replacement solvent before, during, or after desolvation. In the present invention, it is preferable to dissolve the dispersed resin (A) in resin solution and then mix and disperse it with other components.

[0033] When the dispersion resin (A) is a dispersion resin (A) having an alkyl group and / or heterocycle with 12 or more carbon atoms, when the resin is dissolved from a solid state, from the viewpoint of solubility in the solvent, it is preferable to dissolve the resin by mixing it with a solvent whose liquid temperature is 40°C or higher, preferably 50°C or higher, for example, 100°C or lower, preferably 80°C or lower, from the viewpoint of solubility in the solvent. Here, the liquid temperature refers to the temperature of the solvent or resin solution at the time of dissolution. When dissolving the resin, the solid dispersion resin (A) may be mixed with a solvent whose liquid temperature is 40°C or higher and dissolved, or the solid dispersion resin (A) and solvent may be mixed and then heated to a temperature of 60°C or higher. When dissolving the resin, components other than the dispersion resin (A) and solvent may be included. The solvent used for dissolving the resin is not particularly limited. One or more solvents can be used as appropriate. Of these, it is preferable to use N-methyl-2-pyrrolidone (C), which will be described later. It is preferable to cool the dissolved resin solution to a predetermined temperature in the range of 10°C to 40°C. The cooling rate during cooling should be defined by the following formula: Cooling rate = (Solution temperature at the start of cooling - Solution temperature at the end of cooling) / Cooling time. A cooling rate of 0.5°C / min or more, preferably 1°C / min or more, is preferable from the viewpoint of preventing precipitation.

[0034] (Hansen Solubility Parameter) The Hansen solubility parameter (HSP), published by Charles M. Hansen, is known as an indicator of solubility that shows how much of one substance dissolves in another. For example, water and oil generally do not mix, because they have different properties. In the Hansen solubility parameter, three items related to the properties of a substance related to solubility are expressed numerically for each substance: the dispersion term δD, the polarity term δP, and the hydrogen bonding term δH. Here, the dispersion term δD is a value that represents the magnitude of van der Waals forces, the polarity term δP is a value that represents the magnitude of the dipole moment, and the hydrogen bonding term δH is a value that represents the magnitude of hydrogen bonds.

[0035] The Hansen solubility parameter terms (δD, δP, δH) are plotted in a three-dimensional orthogonal coordinate system (Hansen solubility parameter space: HSP space) to examine solubility. For example, the Hansen solubility parameters for solvent α and solid β can be plotted in HSP space at coordinates α(Dα, Pα, Hα) for solution α and β(Dβ, Pβ, Hβ) for solid β. The distance Ra (HSPdistance: Ra) between coordinates α and β is given by the following formula: It can be calculated by [method].

[0036] The shorter the distance Ra between coordinates α and β (the smaller the value of Ra), the more similar the properties of solution α and solid β are, and therefore, solid β is more easily dissolved in solution α. ​​On the other hand, the longer the Ra (the larger the value of Ra), the less similar the properties of solution α and solid β are, and therefore, solid β is less easily dissolved in solution α. ​​In the carbon nanotube dispersion paste of the present invention, N-methyl-2-pyrrolidone (C) corresponds to the above solution α, and the dispersion resin (A) corresponds to the above solid β.

[0037] Hansen solubility parameters can be calculated using the chemical structure and composition ratio of the components, as well as experimental results. In this case, they can be determined using HSPiP (Hansen Solubility Parameters in Practice: Windows® software for efficiently handling HSP), developed by Hansen et al. This software HSPiP is available from "http: / / www.hansen-solubility.com / " as of August 2, 2024. All Hansen solubility parameters in this invention were determined using HSPiP (ver. 5.3.04). Hansen solubility parameters (δD, δP, δH) can also be calculated for mixed solvents containing multiple solvents.

[0038] In the carbon nanotube dispersion paste of the present invention, the dispersion term δD of the Hansen solubility parameter of the dispersion resin (A) is 16.35 or higher. Preferably it can be 16.4 or higher, more preferably 16.5 or higher, for example 17.1 or lower, preferably 17.0 or lower, more preferably 16.9 or lower, for example 16.35 or higher and 17.1 or lower, for example 16.35 or higher and 17.0 or lower, for example 16.35 or higher and 16.9 or lower, for example 16.4 or higher and 17.1 or lower, for example 16.4 or higher and 17.0 or lower, for example 16.4 or higher and 16.9 or lower, for example 16.5 or higher and 17.1 or lower, for example 16.5 or higher and 17.0 or lower, for example 16.5 or higher and 16.9 or lower.

[0039] In the carbon nanotube dispersion paste of the present invention, the Ra of the dispersion resin (A) in relation to N-methyl-2-pyrrolidone (C), based on the Hansen solubility parameter, is 10.5 or less. Preferably, it can be 10.2 or less, more preferably 10.0 or less, for example, 6.5 or more, preferably 7.3 or more, more preferably 7.9 or more, for example, 6.5 to 10.5, for example, 6.5 to 10.2, for example, 6.5 to 10.0, for example, 7.3 to 10.5, for example, 7.3 to 10.2, for example, 7.3 to 10.0, for example, 7.9 to 10.5, for example, 7.9 to 10.2, for example, 7.9 to 10.0. In the present invention, it is preferable that the dispersion resin (A) dissolves in N-methyl-2-pyrrolidone (C) (Ra is 10.5 or less), but it has been found that if the solubility is further reduced to a certain extent (Ra is above a certain value), the dispersion resin can be adsorbed onto carbon nanotubes. Therefore, it has been found that when Ra is within a certain range, the dispersibility, initial viscosity, and / or storage stability of the dispersion paste are balanced and suitable performance is achieved. Furthermore, since the dispersion term δD is a value that represents the magnitude of the van der Waals force, when it is above a certain value (dispersion term δD is 16.35 or more), the interaction with carbon nanotubes improves, and it is considered that the dispersibility, initial viscosity, and / or storage stability are balanced and suitable performance is achieved. Conversely, if the interaction is too strong, the carbon nanotubes may aggregate, so it is preferable that it be within a certain range.

[0040] (Polar functional groups) The dispersion resin (A) may have at least one polar functional group selected from the group consisting of amide groups, imide groups, hydroxyl groups, carboxyl groups, sulfonic acid groups, phosphate groups, amino groups, and cyano groups, and the concentration of the polar functional group may be 0.1 mmol / g or more and 8.5 mmol / g or less.

[0041] The polar functional group is preferably at least one of a hydroxyl group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, an amino group, and a cyano group, more preferably a hydroxyl group, an amino group and / or a cyano group, and even more preferably an amino group and / or a cyano group. The amino group is, for example, usually a secondary or tertiary amino group, with a tertiary amino group being preferred. In the present invention, the carboxyl group may be a carboxylate salt, the sulfonic acid group may be a sulfonate salt, the phosphoric acid group may be a phosphate salt, and the amino group may be an amine salt.

[0042] The concentration of polar functional groups is 0.1 mmol / g or more and 8.5 mmol / g or less. Preferably it can be 0.2 mmol / g or more, more preferably 0.3 mmol / g or more, even more preferably 0.4 mmol / g or more, preferably 6.0 mmol / g or less, more preferably 4.0 mmol / g or less, and even more preferably 2.0 mmol / g or less.

[0043] (Content of Dispersion Resin (A)) The content of dispersion resin (A) in the carbon nanotube dispersion paste is not particularly limited. Based on 100% by mass of the total amount of carbon nanotube dispersion paste, it can be, for example, 0.1% by mass or more, preferably 0.4% by mass or more, more preferably 0.7% by mass or more, and can be, for example, 10% by mass or less, preferably 5% by mass or less, and more preferably 2% by mass or less. Also, based on 100% by mass of the total solid content of the carbon nanotube dispersion paste, it can be, for example, 0.1% by mass or more, preferably 1% by mass or more, more preferably 3% by mass or more, and can be, for example, 40% by mass or less, preferably 30% by mass or less, and more preferably 20% by mass or less.

[0044] Furthermore, the content of the dispersed resin (A) in the carbon nanotube dispersion paste can be, for example, 0.1% by mass or more, preferably 1% by mass or more, more preferably 5% by mass or more, based on the carbon nanotube (B) content of 100% by mass, and can be, for example, 150% by mass or less, preferably 120% by mass or less, more preferably 80% by mass or less.

[0045] <Carbon Nanotubes (B)> The carbon nanotube dispersion paste of the present invention contains carbon nanotubes (B). Carbon nanotubes (B) are not particularly limited. One or more single-walled carbon nanotubes and multi-walled carbon nanotubes can be used. In particular, multi-walled carbon nanotubes are preferred due to their viscosity, conductivity, and cost.

[0046] The average outer diameter of the carbon nanotubes (B) is, for example, 1 nm or more, preferably 3 nm or more, more preferably 5 nm or more, and for example, 30 nm or less, preferably 28 nm or less, more preferably 25 nm or less.

[0047] The average length of the carbon nanotubes (B) is, for example, 0.1 μm or more, preferably 1 μm or more, more preferably 5 μm or more, and for example, 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less.

[0048] Carbon nanotubes (B) showed a Raman spectrum of 1560 cm⁻¹. －１ More than 1600cm －１ The maximum peak intensity within the following range is G, 1310 cm. －１ 1350cm or more －１ The G / D ratio, where D is the maximum peak intensity within the following range, is, for example, 0.1 or more, preferably 0.4 or more, more preferably 0.6 or more, and for example, 5.0 or less, preferably 3.0 or less, more preferably 1.0 or less. A G / D ratio within the range of 0.1 to 5.0 is preferable because it tends to have high conductivity due to fewer defects and crystal interfaces on the carbon surface. The Raman spectrum of carbon nanotube (B) can be obtained, for example, by placing the carbon nanotube in a Raman microscope (manufactured by Horiba, Ltd., product name "XploRA") and measuring it using a laser wavelength of 532 nm.

[0049] The BET specific surface area of ​​carbon nanotubes (B) is typically 100 m, considering the relationship between viscosity and conductivity. ２ / g or more, preferably 130m ２ / g or more, more preferably 160m ２It is 1 / g or more, and usually 800m ２ / g or less, preferably 600m ２ / g or less, more preferably 400m ２ It is less than / g. The BET specific surface area of ​​carbon nanotubes (B) can be calculated by the BET method using nitrogen adsorption measurement. Specifically, for example, in accordance with JIS Z8830:2013, the BET specific surface area (m²) can be calculated using a specific surface area measuring device (BERSORP-MAX (Microtrac-Bell Co., Ltd.)). ２ It can measure ( / g).

[0050] The amount of acidic groups in the carbon nanotube (B) described above is usually 0.01 mmol / g or more, preferably 0.02 mmol / g or more, and usually 1.0 mmol / g or less, preferably 0.5 mmol / g or less, more preferably 0.2 mmol / g or less, and even more preferably 0.1 mmol / g or less, from the viewpoint of dispersibility and storability. If the amount of acidic groups is 0.01 mmol / g or more, dispersibility is good, and if it is 1.0 mmol / g or less, storability is good.

[0051] The above acidic groups can be imparted to carbon nanotubes by acid treatment as described below.

[0052] (Acid Treatment Method) The acid treatment method is not particularly limited as long as the carbon nanotubes can be brought into contact with an acid, but a method of immersing the carbon nanotubes in an acid treatment solution (an aqueous solution of acid) is preferred. The acid contained in the acid treatment solution is not particularly limited, but for example, one or more selected from the group consisting of nitric acid, sulfuric acid, hydrochloric acid, etc. Among these, nitric acid and / or sulfuric acid are preferred. The amount of acidic groups in the carbon nanotubes can be adjusted by the concentration of the acid treatment solution, temperature, treatment time, etc.

[0053] After acid treatment, excess acid components adhering to the surface can be removed by the washing method described later to obtain acid-treated carbon nanotubes. There are no particular limitations on the method for washing the acid-treated carbon nanotubes, but washing with water is preferred. For example, carbon nanotubes can be recovered from the acid-treated carbon nanotubes by a known method such as filtration, and then the carbon nanotubes can be washed with water. After the above washing, if necessary, the water adhering to the surface can be removed by drying to obtain the acid-treated carbon nanotubes.

[0054] The carbon nanotube (B) content in the carbon nanotube dispersion paste is not particularly limited. Based on 100% by mass of the total amount of the carbon nanotube dispersion paste, it can be, for example, 0.05% by mass or more, preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and can be, for example, 10% by mass or less, preferably 7% by mass or less, and more preferably 5% by mass or less. Also, based on 100% by mass of the total amount of solids in the carbon nanotube dispersion paste, it can be, for example, 30% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, and can be, for example, 90% by mass or less, preferably 85% by mass or less, and more preferably 80% by mass or less.

[0055] <N-methyl-2-pyrrolidone (C)> The carbon nanotube dispersion paste of the present invention contains N-methyl-2-pyrrolidone (C). The N-methyl-2-pyrrolidone (C) is not particularly limited. A commercially available N-methyl-2-pyrrolidone reagent (solvent) can be used, and recycled N-methyl-2-pyrrolidone can also be used. Recycled N-methyl-2-pyrrolidone is obtained by recovering a used product and purifying it as necessary. For example, N-methyl-2-pyrrolidone recovered during heating and drying when forming a composite layer on a current collector to create battery electrodes using a composite paste for lithium-ion secondary batteries containing the carbon nanotube dispersion paste of the present invention can be used. Furthermore, the term "using recycled products" refers to the fact that the carbon nanotube dispersion paste according to the present invention contains, for example, 5% by mass or more, preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more of recycled N-methyl-2-pyrrolidone (C). In the present invention, using recycled N-methyl-2-pyrrolidone is advantageous in terms of waste reduction, environmental compliance, and / or raw material cost reduction.

[0056] The water content of N-methyl-2-pyrrolidone (C) is preferably less than 10,000 ppm, more preferably less than 7,500 ppm, even more preferably less than 5,000 ppm, particularly preferably less than 2,500 ppm, most preferably less than 1,000 ppm, and can be, for example, 100 ppm or more, preferably 200 ppm or more, and more preferably 500 ppm or more. If the water content of N-methyl-2-pyrrolidone (C) is 10,000 ppm or more, the carbon nanotube dispersion paste and the lithium-ion secondary battery composite paste containing the carbon nanotube dispersion paste may become highly viscous (thickened) or gel. The water content of N-methyl-2-pyrrolidone (C) can be measured by Karl Fischer coulometric titration. For example, a Karl Fischer moisture meter (manufactured by Kyoto Electronics Manufacturing Co., Ltd., product name "MKC-610") can be used to measure moisture content by setting the moisture vaporizer (manufactured by Kyoto Electronics Co., Ltd., product name "ADP-611") equipped in the device to a temperature of 130°C.

[0057] The amine component content of N-methyl-2-pyrrolidone (C) is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less. The amine component of N-methyl-2-pyrrolidone (C) originates from amine components contained as impurities, and also from amine components contained in the lithium-ion secondary battery composite paste in the recycled N-methyl-2-pyrrolidone. Examples of amine components contained in N-methyl-2-pyrrolidone (C) include one or more of the amine components in the high-polarity low-molecular-weight component (E) described later. The amine component content of N-methyl-2-pyrrolidone (C) can be quantified by general analysis such as ion chromatography-mass spectrometry (IC-MS). The content can be quantified by creating a calibration curve in advance for the peaks of amine species that are expected to be present. By limiting the amine component content of N-methyl-2-pyrrolidone (C) to 1% by mass or less, it becomes possible to maintain a consistent viscosity and thickening tendency of the carbon nanotube dispersion paste, which can be affected by differences in manufacturing lots of N-methyl-2-pyrrolidone, and also solve the problem of odor caused by amine compounds.

[0058] When recycled N-methyl-2-pyrrolidone (C) is used, and the carbon nanotube dispersion paste of the present invention contains a highly polar, low molecular weight component (E) described later, it is necessary to remove the highly polar, low molecular weight component (E) when reusing N-methyl-2-pyrrolidone (C) as a recycled product. Therefore, when the boiling point of N-methyl-2-pyrrolidone (C) is (Xc)°C and the boiling point of the highly polar, low molecular weight component (E) is (Xe)°C, it is preferable that (Xc)-10 > (Xe), and (Xc)-15 > (Xe) from the viewpoint of distillation (removal of the highly polar, low molecular weight component (E)). Furthermore, it is preferable that the highly polar, low molecular weight component (E) includes an amine compound (E1).

[0059] The content of N-methyl-2-pyrrolidone (C) in the carbon nanotube dispersion paste is not particularly limited. Based on 100% by mass of the total amount of the carbon nanotube dispersion paste, it can be, for example, 40% by mass or more, preferably 60% by mass or more, more preferably 80% by mass or more, and can be, for example, 99% by mass or less, preferably 98% by mass or less, and more preferably 97% by mass or less. Furthermore, the content of N-methyl-2-pyrrolidone (C) in the carbon nanotube dispersion paste can be such that the solid content of the carbon nanotube dispersion paste is, for example, 1% by mass or more, preferably 2% by mass or more, more preferably 3% by mass or more, and can be such that the solid content is 60% by mass or less, preferably 40% by mass or less, and more preferably 20% by mass or less.

[0060] <Polyvinylidene fluoride resin (D)> The carbon nanotube dispersion paste of the present invention may contain polyvinylidene fluoride resin (D). Polyvinylidene fluoride resin is a resin intended for forming electrode layers and can be included in the carbon nanotube dispersion paste of the present invention as needed. Polyvinylidene fluoride resin (D) is an essential component in the composite paste for lithium-ion secondary batteries described later.

[0061] As the polyvinylidene fluoride resin (D), polyvinylidene fluoride (a homopolymer of vinylidene fluoride) can be used. Modified polyvinylidene fluoride (D1), which has undergone various modifications, can also be suitably used, and it is preferable that it has polar functional groups from the viewpoint of adhesion to the substrate. Examples of polar functional groups include one or more selected from the group consisting of carboxyl groups, carboxylic acid bases, sulfonic acid groups, sulfonic acid bases, hydroxyl groups, amino groups, phosphate groups, phosphate bases, silanol groups, cyano groups, pyrrolidone groups, etc. The polyvinylidene fluoride resin (D) may consist of only one type, or it may be composed of two or more types of polyvinylidene fluoride resins.

[0062] The weight-average molecular weight of the polyvinylidene fluoride resin (D) is, from the viewpoint of adhesion to the substrate, reinforcement of film properties, and solvent resistance, for example, 100,000 or more, preferably 500,000 or more, more preferably 650,000 or more, and for example, 3 million or less, preferably 2 million or less.

[0063] The polyvinylidene fluoride resin (D) described above can be used in the form of a resin solution. The step of converting the polyvinylidene fluoride resin (D) from a solid state into a resin solution preferably includes a step of mixing and dissolving it in a solvent with a liquid temperature of 40°C or higher (preferably 60°C or higher, more preferably 80°C or higher, for example 200°C or lower, preferably 100°C or lower) in advance, from the viewpoint of solubility in the solvent. Here, the liquid temperature refers to the temperature of the solvent or resin solution at the time of dissolution. As a method for preparing a resin solution of polyvinylidene fluoride resin (D), for example, solid polyvinylidene fluoride resin (D) may be mixed and dissolved in a solvent with a liquid temperature of 40°C or higher in advance, or solid polyvinylidene (E) may be mixed with a solvent and then heated to a temperature of 40°C or higher. One type of solvent may be used alone or two or more types may be used in combination. Furthermore, when preparing a resin solution of polyvinylidene fluoride (D), it is preferable to heat the resin solution to a temperature of 40°C or higher and then cool it to a predetermined temperature of 10°C or higher but less than 40°C. When cooling, it is preferable from the viewpoint of preventing the precipitation of polyvinylidene fluoride (D) that the cooling rate, defined by the following formula: Cooling rate (°C / min) = (Solution temperature at the start of cooling - Solution temperature at the end of cooling) / Cooling time, be 0.5°C / min or higher (preferably 1°C / min or higher).

[0064] As the solvent, the aforementioned N-methyl-2-pyrrolidone can be used, and other solvents listed in the section on other components described later can also be used. Furthermore, the resin solution of polyvinylidene fluoride resin (D) may contain components other than polyvinylidene fluoride resin (D) and the solvent.

[0065] When the carbon nanotube dispersion paste contains polyvinylidene fluoride resin (D), the content is, for example, 10.0% by mass or more, preferably 30.0% by mass or more, more preferably 40.0% by mass or more, based on 100% by mass of the solid content of the carbon nanotube dispersion paste, for example, 99.0% by mass or less, preferably 80.0% by mass or less, more preferably 60.0% by mass or less. Also, based on 100% by mass of the total amount of the carbon nanotube dispersion paste, the content is, for example, 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 1% by mass or more, for example, 10% by mass or less, preferably 7% by mass or less, more preferably 5% by mass or less.

[0066] <High-Polarity Low-Molecular-Weight Component (E)> The carbon nanotube dispersion paste of the present invention may contain a high-polarity low-molecular-weight component (E). The high-polarity low-molecular-weight component (E) is a component that improves the wettability of carbon nanotubes and / or the storage stability of the carbon nanotube dispersion paste. Examples of the high-polarity low-molecular-weight component (E) include one or more selected from organic base components, inorganic base components, organic acid components, and inorganic acid components. The molecular weight of the high-polarity low-molecular-weight component (E) is less than 1200, preferably 1000 or less, more preferably 800 or less, even more preferably 500 or less, even more preferably 350 or less, and particularly preferably 250 or less.

[0067] Examples of organic base components include one or more amine compounds (E1). Examples of amine compounds (E1) include ammonia, primary amines, secondary amines, tertiary amines, etc.

[0068] Examples of primary amines include ethylamine, n-propylamine, sec-propylamine, n-butylamine, sec-butylamine, i-butylamine, tert-butylamine, pentylamine, hexylamine, heptylamine, octylamine, decylamine, laurylamine, mystyrylamine, 1,2-dimethylhexylamine, 3-pentylamine, 2-ethylhexylamine, allylamine, aminoethanol, 1-aminopropanol, 2-aminopropanol, aminobutanol, aminopentanol, aminohexanol, 3-ethoxypropylamine, 3-propoxypropylamine, 3-isopropoxypropylamine, 3-butoxypropylamine, 3-isobutoxypropylamine, 3-(2-ethylhexyloxy)propylamine, aminocyclopentane, aminocyclohexane, aminonorbornene, aminomethylcyclohexane, aminobenzene, benzylamine, phenethylamine, α-phenylethylamine, naphthylamine, Primary monoamines such as furfurylamine; ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,2-diaminobutane, 1,3-diaminobutane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, dimethylaminopropylamine, diethylaminopropylamine, bis-(3-aminopropyl) ether, 1,2-bis-(3-aminopropoxy)ethane, 1,3-bis -(3-aminopropoxy)-2,2'-dimethylpropane, aminoethylethanolamine, 1,2-bisaminocyclohexane, 1,3-bisaminocyclohexane, 1,4-bisaminocyclohexane, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, 1,3-bisaminoethylcyclohexane, 1,4-bisaminoethylcyclohexane, 1,3-bisaminopropylcyclohexane, 1,4-bisaminopropylcyclohexane, hydrogenated 4,4'-Diaminodiphenylmethane, 2-Aminopiperidine, 4-Aminopiperidine, 2-Aminomethylpiperidine, 4-Aminomethylpiperidine, 2-Aminoethylpiperidine, 4-Aminoethylpiperidine, N-Aminoethylpiperidine, N-Aminopropylpiperidine, N-Aminoethylmorpholine, N-Aminopropylmorpholine, Isophoronediamine, Menthanediamine, 1,4-Bisaminopropylpiperazine, o-Phenylenediamine, m-Phenylenediamine, p-Phenylenediamine, 2,4-Tolylenediamine, 2,6-Tolylenediamine, 2,4-Toluenediamine, m-Aminobenzylamine, 4-Chloro-o-Phenylenediamine, Tetrachloro-p-Xylylenediamine, 4-Methoxy-6-methyl-m-Phenylenediamine, m-Xylylenediamine, p-Xylylenediamine, 1,5-Naphthalenediamine, 2,6-Naphthalenediamine, Benzidine, 4,4'-Bi Su(o-toluidine), dianisidine, 4,4'-diaminodiphenylmethane, 2,2-(4,4'-diaminodiphenyl)propane, 4,4'-diaminodiphenyl ether, 4,4'-thiodianiline, 4,4'-diaminodiphenylsulfone, 4,4'-diaminoditolylsulfone, methylenebis(o-chloroaniline), 3,9-bis(3-aminopropyl)2,4,8,10-tetraoxaspiro[5.5]undecane, diethylenetri One or more examples include mine, iminobispropylamine, methyliminobispropylamine, bis(hexamethylene)triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, N-aminoethylpiperazine, N-aminopropylpiperazine, 1,4-bis(aminoethylpiperazine), 1,4-bis(aminopropylpiperazine), 2,6-diaminopyridine, and bis(3,4-diaminophenyl)sulfone.

[0069] Examples of secondary amines include secondary monoamines such as diethylamine, dipropylamine, di-n-butylamine, di-sec-butylamine, diisobutylamine, di-n-pentylamine, di-3-pentylamine, dihexylamine, dioctylamine, di(2-ethylhexyl)amine, methylhexylamine, diallylamine, pyrrolidine, piperidine, 2,4-lupetidine, 2,6-lupetidine, 3,5-lupetidine, diphenylamine, N-methylaniline, N-ethylaniline, dibenzylamine, methylbenzylamine, dinaphthylamine, pyrrole, indoline, indole, morpholine, etc.; N,N'-dimethylethylenediamine, N,N'-dimethyl-1,2-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N,N'-dimethyl-1,2-diaminobutane, N,N'-dimethyl-1,3-diaminobutane, N N'-dimethyl-1,4-diaminobutane, N,N'-dimethyl-1,5-diaminopentane, N,N'-dimethyl-1,6-diaminohexane, N,N'-dimethyl-1,7-diaminoheptane, N,N'-diethylethylenediamine, N,N'-diethyl-1,2-diaminopropane, N,N'-diethyl-1,3-diaminopropane, N,N'-diethyl-1,2-diaminobutane, N,N'-diethyl-1,3-diaminobutane One or more examples include minobutane, N,N'-diethyl-1,4-diaminobutane, N,N'-diethyl-1,6-diaminohexane, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 2,6-dimethylpiperazine, homopiperazine, 1,1-di-(4-piperidyl)methane, 1,2-di-(4-piperidyl)ethane, 1,3-di-(4-piperidyl)propane, and 1,4-di-(4-piperidyl)butane.

[0070] Examples of tertiary amines include trimethylamine, triethylamine, tri-n-propylamine, tri-iso-propylamine, tri-1,2-dimethylpropylamine, tri-3-methoxypropylamine, tri-n-butylamine, tri-iso-butylamine, tri-sec-butylamine, tri-pentylamine, tri-3-pentylamine, tri-n-hexylamine, tri-n-octylamine, tri-2-ethylhexylamine, tri-dodecylamine, tri-laurylamine, dicyclohexylethylamine, cyclohexyldiethylamine, tricyclohexylamine, N,N-dimethylhexylamine, N-methyldihexylamine, N,N-dimethylcyclohexylamine, N-methyldicyclohexylamine, N,N-diethylethanolamine, N,N-dimethylethanolamine, N-ethyldiethanolamine, triethanolamine, tribenzylamine, N,N-dimethylbenzylamine, diethyl Tertiary monoamines such as benzylamine, triphenylamine, N,N-dimethylamino-p-cresol, N,N-dimethylaminomethylphenol, 2-(N,N-dimethylaminomethyl)phenol, N,N-dimethylaniline, N,N-diethylaniline, pyridine, quinoline, N-methylmorpholine, N-methylpiperidine, 2-(2-dimethylaminoethoxy)-4-methyl-1,3,2-dioxabornane, 2-,3-,4-picoline; tetramethylethylenedi One or more examples include amines, pyrazines, N,N'-dimethylpiperazine, N,N'-bis((2-hydroxy)propyl)piperazine, hexamethylenetetramine, N,N,N',N'-tetramethyl-1,3-butanamine, 2-dimethylamino-2-hydroxypropane, diethylaminoethanol, N,N,N-tris(3-dimethylaminopropyl)amine, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, and heptamethylisobiguanide.

[0071] Examples of inorganic base components include one or more metal hydroxides (such as sodium hydroxide and potassium hydroxide).

[0072] Examples of organic acid components include one or more organic carboxylic acids (formic acid, acetic acid, propionic acid, benzoic acid, phthalic acid, etc.), organic sulfonic acids (benzenesulfonic acid, etc.), organic phosphonic acids, and their anhydrides.

[0073] Examples of inorganic acid components include one or more of the following: hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.

[0074] As the highly polar, low molecular weight component (E), an amine compound (E1) can be used in combination with one or more acidic, highly polar, low molecular weight components, such as organic acid components and / or inorganic acid components. Alternatively, an amine compound (E1) can be used in combination with one or more organic bases and / or inorganic bases.

[0075] In the present invention, it is preferable to include an amine compound (E1) as the highly polar, low molecular weight component (E). Among these, primary amine compounds are preferred, and monovalent amine compounds (monoamines) are preferred.

[0076] Examples of the above-mentioned amine compound (E1) include aliphatic amines, alicyclic amines, aromatic amines, alkanolamines, etc., all of which can be suitably used, but aromatic amines are preferred.

[0077] It is preferable that no amine compound remains in the mixture layer and / or electrode layer after drying. For this reason, the weight-average molecular weight of the amine compound (E1) is preferably less than 1,000, more preferably 800 or less, even more preferably 500 or less, particularly preferably 350 or less, and even more preferably 250 or less. For the same reason, the boiling point of the amine compound is preferably 400°C or less, more preferably 300°C or less, and even more preferably 200°C or less. If the boiling point is low, there is a possibility of volatilization during manufacturing or storage, and furthermore, from the viewpoint of odor, the lower limit of the boiling point is preferably 50°C or higher, and more preferably 100°C or higher.

[0078] The amine value of the amine compound (E1) is usually 5 mg KOH / g or more, preferably 50 mg KOH / g or more, more preferably 105 mg KOH / g or more, and is usually within the range of 1,000 mg KOH / g or less.

[0079] The content of the highly polar, low molecular weight component (E) in the carbon nanotube dispersion paste is 0% by mass or more, based on 100% by mass of the total amount of the carbon nanotube dispersion paste. For example, it can be 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and for example, 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less.

[0080] The content of the highly polar, low molecular weight component (E) relative to 100% by mass of the solid content of the carbon nanotube dispersion paste is 0% by mass or more, for example, 1% by mass or more, preferably 1.5% by mass or more, more preferably 2% by mass or more, for example, 600% by mass or less, preferably 300% by mass or less, more preferably 50% by mass or less.

[0081] The content of the highly polar, low molecular weight component (E) relative to 100% by mass of the solid content of carbon nanotubes (B) is 0% by mass or more, for example, 1% by mass or more, preferably 2% by mass or more, more preferably 5% by mass or more, for example, 1,000% by mass or less, preferably 500% by mass or less, more preferably 50% by mass or less.

[0082] Furthermore, if the carbon nanotube dispersion paste used in the manufacturing method of the present invention contains a highly polar, low molecular weight component (E), the content of the highly polar, low molecular weight component (E) per 100 parts by mass of carbon nanotube (B) is α (parts by mass), and the BET specific surface area of ​​carbon nanotube (B) is β (m²). ２ The value of X in the following formula (I), where ( / g), is usually 1 or more, preferably 5 or more, more preferably 10 or more, and usually within the range of 2,500 or less, preferably 1,000 or less, more preferably 300 or less, and even more preferably 100 or less. X = α / β × 300 ... (I) We found that within this range, the surface of the carbon nanotube (B) can be sufficiently wetted with the highly polar, low molecular weight component (E), thereby improving the dispersibility (including viscosity) and storage stability (including suppression of thickening) of the carbon nanotube (B).

[0083] If the above upper limit is exceeded, the content of high-polarity, low-molecular-weight components (E) relative to the surface area of ​​carbon nanotubes (B) is excessive (resulting in odor and increased costs), and if the above lower limit is exceeded, the content of high-polarity, low-molecular-weight components (E) relative to the surface area of ​​carbon nanotubes (B) is insufficient.

[0084] In the carbon nanotube dispersion paste, the mass-based content ratio of N-methyl-2-pyrrolidone (C) to the highly polar, low molecular weight component (E) is in the range of 100 / 0 to 100 / 10, for example, in the range of 100 / 0.01 to 100 / 10, preferably in the range of 100 / 0.02 to 100 / 7, more preferably in the range of 100 / 0.05 to 100 / 5, and even more preferably in the range of 100 / 0.1 to 100 / 4.

[0085] The content of the amine compound (E1) in the highly polar, low molecular weight component (E) is, for example, 50% by mass or more, preferably 75% by mass or more, and more preferably 95% by mass or more, based on 100% by mass of the highly polar, low molecular weight component (E).

[0086] High-polarity, low-molecular-weight components (E), especially amine compounds (E1), often have strong odors, which can worsen the working environment during compounding and drying. Furthermore, they are generally expensive, potentially increasing costs. Therefore, the content of high-molecular-weight, low-molecular-weight components (E), particularly amine compounds (E1), should be kept to the minimum necessary.

[0087] <Other Components> In addition to components (A) to (C) and components (D) and (E) which may be included as needed, the carbon nanotube dispersion paste of the present invention may further contain other components. Examples of other components include one or more selected from the group consisting of pigments other than carbon nanotubes (B), solvents other than N-methyl-2-pyrrolidone (C), resins other than dispersion resin (A) and polyvinylidene fluoride (D), dehydrating agents, neutralizing agents, defoaming agents, preservatives, rust inhibitors, plasticizers, etc.

[0088] (Pigments other than carbon nanotubes (B)) Examples of pigments other than carbon nanotubes (B) include one or more selected from the group consisting of conductive pigments other than carbon nanotubes (B1) (B1); white pigments such as titanium white and zinc oxide; blue pigments such as cyanine blue and induthlene blue; green pigments such as cyanine green and verdigris; organic red pigments such as azo and quinacridone, red pigments such as red iron oxide; organic yellow pigments such as benzimimidazolone, isoindolinone, isoindoline and quinophthalone, yellow pigments such as titanium yellow and lead yellow, etc.

[0089] Examples of conductive pigments (B1) include at least one conductive carbon selected from the group consisting of acetylene black, Ketjen black, furnace black, thermal black, graphene, graphite, carbon nanofiber, etc. Preferably, it is one or more selected from the group consisting of acetylene black, Ketjen black, furnace black, and thermal black, more preferably one or more selected from the group consisting of acetylene black and Ketjen black, and even more preferably acetylene black.

[0090] The average primary particle diameter of the conductive pigment (B1) is, for example, 10 nm or more, preferably 20 nm or more, and for example, 80 nm or less, preferably 70 nm or less. Here, the average primary particle diameter is the average particle diameter of the primary particles obtained by observing the conductive pigment (B1) with an electron microscope, determining the projected area of ​​100 particles, calculating the diameter when assuming a circle equal to that area, and then simply averaging the diameters of the 100 particles. If the pigment is in an aggregated state, the calculation is performed using the primary particles that constitute the aggregated particles.

[0091] The BET specific surface area of ​​the conductive pigment (B1) is not particularly limited. Based on the relationship between viscosity and conductivity, for example, 1 m ２ / g or more, preferably 10m ２ / g or more, more preferably 20m ２ It can be set to 500m or more, for example, 500m ２ Less than or equal to 250mg / g, preferably 250mg ２ / g or less, more preferably 200m ２It can be less than or equal to / g.

[0092] The amount of dibutyl phthalate (DBP) absorbed by the conductive pigment (B1) is not particularly limited. Depending on the relationship between pigment dispersibility and conductivity, it can be, for example, 60 ml / 100 g or more, preferably 150 ml / 100 g or more, and for example, 1,000 ml / 100 g or less, preferably 800 ml / 100 g or less.

[0093] Pigments other than carbon nanotubes (B) can be used for purposes such as color adjustment, conductivity adjustment, and coating film property adjustment, as long as they do not significantly impair the conductivity of the carbon nanotube dispersion paste. Pigments other than carbon nanotubes (B) may be dispersed together with the dispersion resin (A) and carbon nanotubes (B), or they may be mixed as a pigment or pigment paste after the paste has been prepared by dispersing the dispersion resin (A) and carbon nanotubes (B).

[0094] The content of pigments other than the carbon nanotube (B) described above is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less, and particularly preferably substantially absent, based on 100% by mass of all pigments in the carbon nanotube dispersion paste.

[0095] (Solvents other than N-methyl-2-pyrrolidone (C)) Solvents other than N-methyl-2-pyrrolidone (C) are not particularly limited. Organic solvents are preferred. Examples of organic solvents include hydrocarbon solvents such as n-butane, n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane, and cyclobutane; aromatic solvents such as toluene and xylene; ketone solvents such as methyl isobutyl ketone; ether solvents such as n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and diethylene glycol; ethyl acetate, n-butyl acetate, isobutyl acetate, ethyl acetate Examples of solvents include ester solvents such as methyl glycol monomethyl ether acetate and butyl carbitol acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone; alcohol solvents such as ethanol, isopropanol, n-butanol, sec-butanol, and isobutanol; and amide solvents such as equamide (amide solvent, manufactured by Idemitsu Kosan Co., Ltd., trade name), N,N-dimethylformamide, N,N-dimethylacetamide, N-methylformamide, N-methylacetamide, and N-methylpropioamide. For solvents other than N-methyl-2-pyrrolidone (C), a water content of less than 10,000 ppm is preferred.

[0096] (Dehydrating agent) The above dehydrating agent (F) can be any known agent that has a dehydrating effect without particular limitation. It may be a solid dehydrating agent that does not dissolve in the solvent (C) of the paste, or a dehydrating agent that dissolves in the solvent (C). Specifically, for example, solid dehydrating agents such as zeolite, silica gel, calcium oxide, molecular sieve, activated alumina, barium oxide, calcium hydride, sodium sulfate, etc.; phosphate esters such as trimethyl phosphate, tri-2-propyl phosphate, tributyl phosphate, tetraisopropylethylene phosphonate, etc.; phosphine oxides such as tributylphosphine oxide, trioctylphosphine oxide, triphenylphosphine oxide, etc.; methyl orthoformate, etc. One or more selected from the group consisting of: ethyl orthoesters such as ethyl orthoacetate, methyl orthoacetate, ethyl orthoacetate, and ethyl orthobenzoate; acid anhydrides such as oxalic acid anhydride, acetic anhydride, propionic anhydride, butyric acid anhydride, benzoic acid anhydride, trifluoroacetic acid anhydride, disulfuric acid, dinitrogen pentoxide, diphosphoric acid, diphosphorus pentoxide, diphosphorus trioxide, arsenic pentoxide, arsenic trioxide, methanesulfonic acid anhydride, trifluoromethanesulfonic acid anhydride, and sulfobenzoic acid anhydride; etc.

[0097] <Moisture Content of Carbon Nanotube Dispersion Paste> The moisture content of the carbon nanotube dispersion paste of the present invention is not particularly limited. The moisture content of the carbon nanotube dispersion paste can be, for example, 10,000 ppm or less, preferably less than 7,500 ppm, more preferably less than 5,000 ppm, and even more preferably less than 2,500 ppm.

[0098] In the carbon nanotube dispersion paste of the present invention, by setting the water content to 10,000 ppm or less, it is possible to suppress viscosity increase and gelation during storage at high temperatures (e.g., 45°C or higher, particularly 50°C or higher), thereby providing a carbon nanotube dispersion paste with excellent storage stability at high temperatures. The water content of the carbon nanotube dispersion paste can be measured using the same measurement method as for the water content of N-methyl-2-pyrrolidone (C).

[0099] <Viscosity of Carbon Nanotube Dispersion Paste> The viscosity of the carbon nanotube dispersion paste of the present invention is not particularly limited. As for the viscosity of the carbon nanotube dispersion paste, from the viewpoint of pigment dispersibility and storage stability, a shear rate of 2s is considered. －１ In this case, for example, it can be less than 500 mPa·s, preferably less than 200 mPa·s, more preferably less than 50 mPa·s, and for example, it can be 0.1 mPa·s or more, preferably 0.5 mPa·s or more, more preferably 1.0 mPa·s or more. Viscosity can be measured, for example, at 20°C using a cone and plate viscometer (HAAKE Corporation, product name "Mars2", 35 mm diameter, 2° inclined cone and plate).

[0100] <Method for producing carbon nanotube dispersion paste> The method for producing the carbon nanotube dispersion paste of the present invention is not particularly limited. It can be produced by mixing and further dispersing a component containing a dispersion resin (A), carbon nanotubes (B), and N-methyl-2-pyrrolidone (C), and a polyvinylidene fluoride resin (D), a highly polar, low molecular weight component (E), and other components.

[0101] For mixing and dispersion, uniform mixing and dispersion can be achieved using dispersers such as paint shakers, sand mills, ball mills, pebble mills, LMZ mills, DCP pearl mills, planetary ball mills, homogenizers, twin-shaft kneaders, and thin-film rotary high-speed mixers (such as M-Technique's "Creamix"). The order in which each component is mixed and dispersed is not particularly limited. For example, all components can be mixed and dispersed at once, or, for example, some components can be mixed and dispersed first, and then the remaining components can be mixed and dispersed.

[0102] In the present invention, it is preferable to sequentially perform the following steps: Step 1: Adding a component containing carbon nanotubes (B) in an amount of 70% by mass or less (preferably 50% by mass or less), based on 100% by mass of the total amount of carbon nanotubes (B) contained in the carbon nanotube dispersion paste obtained after dispersion, along with a dispersion resin (A) and N-methyl-2-pyrrolidone (C), to a disperser and mixing and performing a dispersion treatment; and Step 2: Then, adding carbon nanotubes (B) to the disperser until the desired concentration is reached and performing a dispersion treatment. In this case, it is preferable that the dispersion treatment time in Step 1 be at least 30 seconds or more (preferably 1 minute or more). By performing mixing and dispersion in Steps 1 and 2, aggregation of carbon nanotubes (B) is mitigated, and even in carbon nanotube dispersion pastes with a high concentration of carbon nanotubes (B), a paste with good dispersibility and homogeneity can be obtained. Furthermore, the composite layer (coating layer) obtained from the composite paste for lithium-ion secondary batteries containing the carbon nanotube dispersion paste has excellent finish, conductivity, and battery performance.

[0103] [Compound Paste for Lithium-Ion Secondary Batteries] The composite paste for lithium-ion secondary batteries of the present invention is a composite paste for lithium-ion secondary batteries containing a dispersion resin (A), carbon nanotubes (B), N-methyl-2-pyrrolidone (C), polyvinylidene fluoride resin (D), and electrode active material (F), wherein the dispersion term δD of the Hansen solubility parameter of the dispersion resin (A) is 16.35 or higher, and the Ra of the dispersion resin (A) based on the Hansen solubility parameter for N-methyl-2-pyrrolidone (C) is 10.5 or lower.

[0104] The dispersion resin (A), carbon nanotube (B), N-methyl-2-pyrrolidone (C), and polyvinylidene fluoride resin (D) contained in the lithium-ion secondary battery composite paste can be the same as those described in the above [Carbon Nanotube Dispersion Paste] section, namely the dispersion resin (A), carbon nanotube (B), N-methyl-2-pyrrolidone (C), and polyvinylidene fluoride resin (D).

[0105] The lithium-ion secondary battery composite paste of the present invention may contain a highly polar, low molecular weight component (E) from the viewpoint of storage stability at high temperatures and suppression of thickening. The highly polar, low molecular weight component (E) may be the same as the highly polar, low molecular weight component (E) described in the [carbon nanotube dispersion paste] above. The lithium-ion secondary battery composite paste of the present invention preferably contains at least one amine compound (E1) as the highly polar, low molecular weight component (E). The highly polar, low molecular weight component (E) can wet the surface of the carbon nanotubes (B) when brought into contact with the carbon nanotubes (B), thereby mitigating aggregation between the carbon nanotubes (B) and the electrode active material (G) when mixed with the electrode active material (F). For this reason, when the lithium-ion secondary battery composite paste contains a highly polar, low molecular weight component (E), it is preferable to pre-mix the carbon nanotubes (B) and the highly polar, low molecular weight component (E).

[0106] The composite material base of the present invention contains an electrode active material (F). Examples of the electrode active material (F) include alkali metal composite oxides and alkali metal composite phosphates. For example, lithium nickelate (LiNiO) ２ ), lithium manganese (LiMn ２ O ４ ), lithium cobalt oxide (LiCoO ２ ), LiNi ０．５ Mn １．５ O ４ LiNi １／３ Co １／３ Mn １／３ O ２ Lithium composite oxides such as lithium iron phosphate (LiFePO) ４ One or more selected from the group consisting of ); sodium complex oxide; potassium complex oxide, etc. In particular, the electrode active material (F) contains nickel and one or more other transition metals, and the nickel content is preferably 15 mol% or more, and more preferably 30 mol% or more, based on the total number of moles of transition metals. The volume average particle diameter of the electrode active material (F) is not particularly limited. For example, it is 0.5 μm or more, preferably 10 μm or more, and usually 30 μm or less, preferably 20 μm or less.

[0107] Composite pastes for lithium-ion secondary batteries containing electrode active material (F) may thicken during storage. The reason for this thickening during storage is unknown, but it is presumed that alkali metal hydroxides (e.g., LiOH, KOH, NaOH, etc.) derived from the raw materials are present on the particle surface of the electrode active material (F), and that this thickening occurs due to aggregation with carbon nanotubes (B) having an acidic surface. On the other hand, if the composite paste for lithium-ion secondary batteries contains a highly polar, low molecular weight component (E), preferably a basic highly polar, low molecular weight component, and more preferably an amine compound (E1), thickening during storage can be suppressed.

[0108] The lithium-ion secondary battery composite paste of the present invention can use an electrode active material composite (F-1) in which at least a portion of the surface of the electrode active material (F) is coated with carbon nanotubes. The electrode active material composite (F-1) can be obtained by mixing the electrode active material (F), carbon nanotubes, and other components such as solvents and dispersion resins as needed. After mixing, it can be dried as needed, thereby allowing the carbon nanotubes to be more uniformly adsorbed and / or fixed to at least a portion of the surface of the electrode active material (F). Furthermore, in the electrode active material composite (G-1), a uniform conductive network can be formed around the electrode active material because the carbon nanotubes are adsorbed and / or fixed to the surface of the electrode active material. The carbon nanotubes that can be used in forming the electrode active material composite (G-1) are not particularly limited, and for example, the same as the carbon nanotubes (B) described in the [carbon nanotube dispersion paste] above can be used.

[0109] The water content of the electrode active material (F) can be, for example, less than 10,000 ppm, preferably less than 7,500 ppm, more preferably less than 5,000 ppm, even more preferably less than 2,500 ppm, and particularly preferably less than 1,000 ppm, from the viewpoint of suppressing viscosity increase or gelation of the composite paste for lithium-ion secondary batteries.

[0110] The content of the dispersion resin (A) in the lithium-ion secondary battery composite paste is not particularly limited. From the viewpoint of battery performance and paste viscosity, etc., it can be, for example, 0.01% by mass or more, preferably 0.05% by mass or more, and for example, 10% by mass or less, preferably 1% by mass or less, based on 100% by mass of the total solid content of the lithium-ion secondary battery composite paste.

[0111] The carbon nanotube (B) content in the lithium-ion secondary battery composite paste is not particularly limited. From the viewpoint of battery performance, etc., based on 100% by mass of the total solid content of the lithium-ion secondary battery composite paste, it can be, for example, 0.01% by mass or more, preferably 0.05% by mass or more, more preferably 0.1% by mass or more, and for example, 30% by mass or less, preferably 10% by mass or less, more preferably 5% by mass or less.

[0112] The content of N-methyl-2-pyrrolidone (C) in the composite paste for lithium-ion secondary batteries is not particularly limited. From the viewpoint of drying efficiency during composite layer preparation and paste viscosity, etc., the content can be, for example, 1% by mass or more, preferably 4% by mass or more, more preferably 7% by mass or more, based on 100% by mass of the total amount of the composite paste for lithium-ion secondary batteries, and can be, for example, 90% by mass or less, preferably 70% by mass or less, more preferably 50% by mass or less.

[0113] The content of polyvinylidene fluoride resin (D) in the lithium-ion secondary battery composite paste is not particularly limited. From the viewpoint of battery performance and paste viscosity, etc., it can be, for example, 0.05% by mass or more, preferably 0.1% by mass or more, and for example, 10% by mass or less, preferably 2% by mass or less, based on 100% by mass of the total solid content of the lithium-ion secondary battery composite paste.

[0114] The content of electrode active material (F) in the composite paste for lithium-ion secondary batteries is not particularly limited. From the viewpoint of battery capacity, battery resistance, battery performance, etc., the content can be, for example, 20% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, based on 100% by mass of the total solid content of the composite paste for lithium-ion secondary batteries, and can be, for example, 99.85% by mass or less.

[0115] From the viewpoint of suppressing viscosity increase or gelation, the moisture content of the lithium-ion secondary battery composite paste can be, for example, less than 10,000 ppm, preferably less than 7,500 ppm, more preferably less than 5,000 ppm, even more preferably less than 2,500 ppm, and particularly preferably less than 1,000 ppm. Furthermore, due to moisture introduced from the constituent components of the lithium-ion secondary battery composite paste and moisture contamination during the manufacturing process, the moisture content of the lithium-ion secondary battery composite paste can be, for example, 100 ppm or more, preferably 200 ppm or more, and more preferably 500 ppm or more. The lithium-ion secondary battery composite paste of the present invention is preferably substantially aqueous.

[0116] The method for producing the composite paste for lithium-ion secondary batteries is not particularly limited. For example, a carbon nanotube dispersion paste containing a dispersion resin (A), carbon nanotubes (B), N-methyl-2-pyrrolidone (C), and polyvinylidene fluoride resin (D) can be prepared, and then one or more electrode active materials (G) can be mixed and dispersed to produce the composite paste for lithium-ion secondary batteries. Alternatively, for example, a carbon nanotube dispersion paste containing a dispersion resin (A), carbon nanotubes (B), and N-methyl-2-pyrrolidone (C) can be prepared, and then one or more polyvinylidene fluoride resins (D) and one or more electrode active materials (G) can be mixed and dispersed to produce the composite paste for lithium-ion secondary batteries.

[0117] When mixing and dispersing a carbon nanotube dispersion paste with one or more electrode active materials (G), or when mixing and dispersing a carbon nanotube dispersion paste with one or more polyvinylidene fluoride-based resins (D) and one or more electrode active materials (G), known mixers and / or dispersers can be used to uniformly mix the composite paste for lithium-ion secondary batteries. For example, a disperser used for mixing and dispersing each component in the production of a carbon nanotube dispersion paste can be used.

[0118] The lithium-ion secondary battery composite paste of the present invention can be used in the manufacture of the positive or negative electrode of a battery, for example, by applying it to a current collector and drying it to form a composite layer. Preferably, it can be used in the manufacture of the positive electrode of a lithium-ion secondary battery.

[0119] [Electrode layer for non-aqueous electrolyte lithium-ion secondary battery] The electrode layer for a non-aqueous electrolyte lithium-ion secondary battery of the present invention is obtained by coating the [Lithium-ion secondary battery composite paste] onto a current collector.

[0120] The current collector is not particularly limited as long as it is made of a conductive material used in battery electrodes. Examples include metals such as aluminum, copper, titanium, and alloys of two or more of these, carbon materials, and composites thereof. The current collector can be in the form of foil, plate, etc., and is preferably foil. In the present invention, either aluminum foil or copper foil is preferably used.

[0121] The thickness of the electrode layer for a non-aqueous electrolyte lithium-ion secondary battery is not particularly limited. The thickness of the portion of the electrode layer for a non-aqueous electrolyte lithium-ion secondary battery obtained by coating the lithium-ion secondary battery composite paste onto a current collector and drying it can be, for example, 0.04 mm or more, preferably 0.06 mm or more, and can be, for example, 0.30 mm or less, preferably 0.24 mm or less. The method of coating the lithium-ion secondary battery composite paste onto the current collector is not particularly limited. Examples include roller coating and coating methods using a die coater. The temperature and time for drying the lithium-ion secondary battery composite paste coated onto the current collector are not particularly limited. The temperature can be, for example, 80°C or more, preferably 100°C or more, and can be, for example, 250°C or less, preferably 200°C or less. The drying time can be, for example, 5 seconds or more, and can be, for example, 120 minutes or less, preferably 60 minutes or less.

[0122] In this invention, when applying a lithium-ion secondary battery composite paste to a current collector, a primer layer can be formed on the current collector beforehand. The primer layer corresponds to a functional layer or adhesive layer. As a material for forming the primer layer, for example, the aforementioned [carbon nanotube dispersion paste] can be used.

[0123] When a lithium-ion secondary battery composite paste is applied to a current collector and dried to form an electrode layer for a non-aqueous electrolyte lithium-ion secondary battery, all or part of the N-methyl-2-pyrrolidone (C) and, if necessary, the high-polarity, low-molecular-weight component (E) contained in the lithium-ion secondary battery composite paste will volatilize. In the present invention, in order to reduce waste, address environmental concerns, and reduce costs, it is preferable to recover the volatilized N-methyl-2-pyrrolidone (C) and high-polarity, low-molecular-weight component (E), purify them by means of distillation or other means, and reuse them as a recycled N-methyl-2-pyrrolidone product.

[0124] When forming a battery electrode from the electrode layer for a non-aqueous electrolyte lithium-ion secondary battery of the present invention and using it as an electrode for a lithium-ion secondary battery, the presence of impurities such as water in the battery electrode, particularly in the electrode layer for the non-aqueous electrolyte lithium-ion secondary battery, may reduce the cycle life. For example, if the carbon nanotube dispersion paste or the composite paste for lithium-ion secondary batteries contains more water than specified, or if the drying process in the manufacturing process of the electrode layer for the non-aqueous electrolyte lithium-ion secondary battery is insufficient, impurities such as water may remain in the electrode layer for the non-aqueous electrolyte lithium-ion secondary battery, which can cause deterioration of the battery's cycle characteristics. For this reason, the amount of water in the composite paste layer for lithium-ion secondary batteries used in forming the electrode layer for the non-aqueous electrolyte lithium-ion secondary battery can be, for example, less than 1000 ppm, preferably less than 750 ppm, more preferably less than 500 ppm, even more preferably less than 250 ppm, and particularly preferably less than 100 ppm.

[0125] [Electrodes for Non-Aqueous Electrolyte Lithium-Ion Secondary Batteries] The electrode for a non-aqueous electrolyte lithium-ion secondary battery of the present invention has an electrode insulating portion provided at the end or upper layer of the [Electrode Layer for Non-Aqueous Electrolyte Lithium-Ion Secondary Battery]. The electrode insulating portion can be provided, for example, by coating with an insulating paste. The insulating paste is not particularly limited as long as it can form an insulating film. For example, a paste containing an inorganic filler, a binder, a dispersant, and a solvent is preferred. Of these, an insulating paste containing boehmite as the inorganic filler, polyvinylidene fluoride as the binder, and N-methyl-2-pyrrolidone as the solvent is preferred. As an insulating paste, for example, the insulating paste described in International Publication No. 2021 / 193286 can also be used.

[0126] [Non-aqueous electrolyte lithium-ion secondary battery] The non-aqueous electrolyte lithium-ion secondary battery of the present invention comprises at least a positive electrode having an electrode layer for non-aqueous electrolyte lithium-ion secondary batteries, a negative electrode, a non-aqueous electrolyte, and a separator.

[0127] The electrode layer for a non-aqueous electrolyte lithium-ion secondary battery in the positive electrode can be the same as that described in [Electrode Layer for Non-Aqueous Electrolyte Lithium-ion Secondary Battery] above.

[0128] Examples of negative electrodes include carbon, metal, and composite materials in which a negative electrode composite layer containing a negative electrode active material is formed on a current collector.

[0129] As a non-aqueous electrolyte, for example, a solution containing a salt in an organic solvent that is a non-aqueous solvent can be used. Examples of non-aqueous solvents include one or more organic solvents such as carbonates, ethers, esters, nitriles, sulfones, and lactones. Examples of salts include LiPF ６ LiBF ４ LiClO ４ Examples include one or more lithium salts. The concentration of the salt is not particularly limited, but can be, for example, 0.7 mol / L or more and 1.3 mol / L or less.

[0130] Examples of separators include resin sheets. The resin sheet is preferably composed of one or more materials such as polyethylene, polypropylene, polyester, cellulose, and polyamide, and is preferably a porous resin sheet. The porous resin sheet may have a single-layer structure or a laminated structure of two or more layers. The resin sheet may also have a heat-resistant layer as needed. Examples of heat-resistant layers include those formed from a heat-resistant layer-forming material containing an inorganic filler such as alumina, magnesia, or boehmite, a resin binder, and a thickener.

[0131] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these specific embodiments. In each example, "parts" refers to parts by mass, and "%" refers to mass percent. Carbon nanotubes may be abbreviated as "CNT". In the examples, the water content was measured using a Karl Fischer moisture meter (manufactured by Kyoto Electronics Manufacturing Co., Ltd., product name "MKC-610").

[0132] [Production of Dispersion Resin] <Production Example 1> 75 parts of N-methyl-2-pyrrolidone (water content 8000 ppm) were added to a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, and water separator, and the mixture was heated to 120°C under a nitrogen atmosphere. Once 120°C was reached, a mixture of the monomer species shown in Table 1 below (total 100 parts) and 2 parts of 2,2'-azobis(2-methylbutyronitrile) was added dropwise over 3 hours. After the addition was complete, the mixture was aged at 120°C for 30 minutes, and a mixture of 1 part of 2,2'-azobis(2-methylbutyronitrile) and 20 parts of N-methyl-2-pyrrolidone (water content 8000 ppm) was added dropwise over 1 hour. After further aging at 120°C for 1 hour, the mixture was cooled, and N-methyl-2-pyrrolidone was added to obtain a dispersion resin (A-1) with a solid content of 50%. The concentration of polar functional groups was 0.13 (mol / g). The values ​​of the dispersion term δD, Ra, and Mw (weight-average molecular weight) of the Hansen solubility parameters of the obtained dispersed resin are shown in Table 1 below.

[0133] <Production Examples 2-27> Dispersed resins (A-2) to (A-27) with a solid content of 50% were obtained in the same manner as in Production Example 1, except that the monomer species were as shown in Table 1 below. Dispersed resins (A2) to (A27) are all acrylic resins. The values ​​of the Hansen solubility parameters δD, Ra, and Mw (weight-average molecular weight) for the obtained dispersed resins are shown in Table 1 below. The abbreviations for the monomer species in Table 1 above are as follows: • St: Styrene • iBA: i-butyl acrylate (has a hydrocarbon group with 4 carbon atoms) • SLMA: Lauryl methacrylate (has a hydrocarbon group with 12 carbon atoms) • SMA: Stearyl methacrylate (has a hydrocarbon group with 18 carbon atoms) • BEMA: Behenyl methacrylate (has a hydrocarbon group with 22 carbon atoms) • AN: Acrylonitrile • DMAEMA: N,N-dimethylaminoethyl methacrylate

[0134] [Production of Carbon Nanotube Dispersion Paste] <Example (X1)> 900 parts of N-methyl-2-pyrrolidone (water content 8000 ppm), 20 parts of dispersion resin (A-1) (10 parts solids), 5 parts of benzylamine (boiling point 185°C, molecular weight 107), and 30 parts of carbon nanotube CNT1 (see Table 2 below) were mixed in a disperser for 10 minutes with stirring in order, and finally, N-methyl-2-pyrrolidone (water content 8000 ppm) was added to adjust the total mass to 1000 parts. Subsequently, rotor R2 and screen S2.0-24 were attached to a high-speed homogenizer: Creamix CLM-0.8S (product name, manufactured by M-Technique), and the mixture was stirred at a speed of 8000 rpm for 1 minute, and then stirred at a speed of 12000 rpm for 2 minutes to perform the dispersion treatment. Next, a batch-type dispersion process was carried out in 10 passes using a high-pressure homogenizer: NanoVator NVL-ES008A-D10 (product name, manufactured by Yoshida Machinery Co., Ltd.) to obtain a carbon nanotube dispersion paste (X-1). The dispersion process in the high-pressure homogenizer was performed using a straight nozzle NVGL-IT230 (nozzle diameter 230 μm) at a pressure of 100 MPa. All of the above manufacturing processes were carried out in an atmosphere with a dew point of 10°C or lower. After the production of the carbon nanotube dispersion paste, the paste was quickly adjusted to 20°C. The water content of the obtained carbon nanotube dispersion paste (X-1) was 8000 ppm. The carbon nanotube (CNT1) described above is a multi-walled carbon nanotube. The specific surface area (BET specific surface area) in Table 2 above was measured using the method described later.

[0135] <Examples (X2) to (X19), (X29), (X30), Comparative Examples (X20) to (X28)> Carbon nanotube dispersion pastes were obtained in the same manner as in Example (X1), except that the dispersion resin was as described in Table 3 below. The water content of the carbon nanotube dispersion pastes in each example and comparative example was approximately the same as that of the carbon nanotube dispersion paste in Example (X1). The results of the evaluation tests of the carbon nanotube dispersion pastes, described later, are shown in Table 3 below.

[0136] The names of the dispersed resins in Table 3 above are as follows: • A-1 to A-27: Dispersed resins (A-1) to (A-27) obtained in Production Examples 1 to 27 • PVB: Polyvinyl butyral resin (weight-average molecular weight 45,000, hydroxyl group content 12 mol%, butyral group content 87 mol%, acetyl group content 1 mol%, polar functional group concentration 1.0 mmol / g, Hansen solubility parameter dispersion term δD value 16.6, Ra value 9.7) • PVA: Polyvinyl alcohol resin (weight-average molecular weight 26,000, degree of saponification 99.9 mol%, polar functional group concentration 22.7 ( mmol / g), polar functional group type: hydroxyl group, Hansen solubility parameter dispersion term δD value 20.2, Ra value 21.4) • PVP: Polyvinylpyrrolidone resin (weight-average molecular weight 67,000, polar functional group concentration 9.0 (mol / g), polar functional group type: amide group, Hansen solubility parameter dispersion term δD value 19.1, Ra value 5.1)

[0137] <Specific Surface Area (BET Specific Surface Area) of Carbon Nanotubes> The BET specific surface area of ​​carbon nanotubes is determined in accordance with JIS Z8830:2013, using a specific surface area measuring device (BERSORP-MAX (Microtrac-Bell Co., Ltd.)) to obtain the BET specific surface area (m²). ２ The amount (per g) was measured.

[0138] [Manufacturing of composite paste for lithium-ion secondary batteries] <Example (Z1)> While stirring with a disperser, 10 parts of polyvinylidene fluoride solution are mixed with 90 parts of the above carbon nanotube dispersion paste (X-1) and electrode active material particles (composition formula LiNi ０．５ Mn １．５ O ４ Lithium nickel manganese oxide particles with a spinel structure, represented by [formula], average particle size 6 μm, BET specific surface area 0.7 m². ２A lithium-ion secondary battery composite paste (Z-1) was manufactured by sequentially mixing 900 parts of ( / g) with the other ingredients. The water content of the lithium-ion secondary battery composite paste (Z-1) was 1500 ppm. The polyvinylidene fluoride solution used was a resin solution prepared by pre-mixing 5 parts of KF Polymer #9700 (trade name, manufactured by Kureha Corporation, polar group modified polyvinylidene fluoride, molecular weight 800,000-900,000) and 95 parts of N-methyl-2-pyrrolidone (water content 8000 ppm) at a temperature of 50°C.

[0139] <Examples (Z2) to (Z19), (Z29), (Z30), Comparative Examples (Z20) to (Z28)> Lithium-ion secondary battery composite pastes were obtained in the same manner as in Example (Z1), except that the composite paste for lithium-ion secondary batteries was as described in Table 4 below. The water content of the lithium-ion secondary battery composite pastes in each example and comparative example was approximately the same as that of the lithium-ion secondary battery composite paste in Example (Z1).

[0140] [Evaluation Tests] Evaluation tests were conducted on the carbon nanotube dispersion pastes obtained in the above examples and comparative examples. A rating of D in each evaluation test indicates failure. If even one evaluation result is a failure, the carbon nanotube dispersion paste is considered unsuccessful. Note that storage stability evaluation tests were not conducted on carbon nanotube dispersion pastes that received a rating of D for initial viscosity.

[0141] <Dispersibility> The obtained carbon nanotube dispersion paste was evaluated for dispersibility using a particle gauge according to the dispersibility test of JIS K-5600-2-5, based on the following criteria. A: Pigment is dispersed at less than 10 μm. Dispersibility is good. B: Pigment is dispersed at 10 μm or more and less than 40 μm. Dispersibility is moderately good. D: Pigment is dispersed at 40 μm or more, or aggregates are visible. Dispersibility is poor.

[0142] <Initial Viscosity> The obtained carbon nanotube dispersion paste was measured using a cone and plate viscometer (HAAKE Corporation, product name "Mars2", 35 mm diameter, 2° inclined cone and plate) and measured the shear rate at 2.0 sec.－１ The viscosity was measured at 20°C and evaluated according to the following criteria: S: Viscosity is less than 6 Pa·s. Initial viscosity is very good. A: Viscosity is 6 Pa·s or more and less than 12 Pa·s. Initial viscosity is good. B: Viscosity is 12 Pa·s or more and less than 25 Pa·s. Initial viscosity is somewhat good. C: Viscosity is 25 Pa·s or more and less than 50 Pa·s. Initial viscosity is average. D: Viscosity is 50 Pa·s or more. Initial viscosity is poor.

[0143] <Storage Stability> The obtained carbon nanotube dispersion paste was stored at 50°C for 10 days, and the initial viscosity and the viscosity after storage were compared. Viscosity was measured using a cone and plate viscometer (HAAKE Corporation, product name "Mars2", 35 mm diameter, 2° inclined cone and plate) at a shear rate of 2.0 s. －１ The viscosity was measured at 20°C, and the viscosity increase rate was calculated using the following formula. Storage stability was evaluated according to the following criteria: Viscosity increase rate (%) = Viscosity after storage (mPa·s) / Initial viscosity (mPa·s) × 100 - 100 S: Viscosity increase rate (%) after storage is less than 15%. Storage stability is very good. A: Viscosity increase rate (%) after storage is 15% or more and less than 25%. Storage stability is good. B: Viscosity increase rate (%) after storage is 25% or more and less than 70%. Storage stability is somewhat good. C: Viscosity increase rate (%) after storage is 70% or more and less than 250%. Storage stability is average. D: Viscosity increase rate (%) after storage is 250% or more (or gelled and unmeasurable). Storage stability is poor.

[0144] [Manufacturing of Battery Electrode Layers] <Application Example 1Y> The lithium-ion secondary battery composite paste obtained in Example Z6 was applied to both sides of a long aluminum foil (positive electrode current collector) with an average thickness of 15 μm, with a basis weight of 10 mg / cm² per side. ２ A positive electrode layer was formed by applying the material in a strip using a roller coating method to achieve a certain (solid content) and drying it (drying temperature 180°C, 30 minutes). The positive electrode active material layer (positive electrode layer) supported on the positive electrode current collector was rolled using a roll press to adjust its properties. The resulting electrode layer had good finish and other properties.

Claims

1. A carbon nanotube dispersion paste containing a dispersion resin (A), a carbon nanotube (B), and N-methyl-2-pyrrolidone (C), wherein the dispersion term δD of the Hansen solubility parameter of the dispersion resin (A) is 16.35 or higher, and the Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C), based on the Hansen solubility parameter, is 10.5 or lower.

2. The carbon nanotube dispersion paste according to claim 1, wherein the dispersion term δD of the Hansen solubility parameter of the dispersion resin (A) is in the range of 16.5 to 16.

9.

3. The carbon nanotube dispersion paste according to claim 1 or 2, wherein the Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C) is in the range of 7.3 to 10.2, based on the Hansen solubility parameter.

4. The carbon nanotube dispersion paste according to claim 1 or 2, wherein the dispersion resin (A) has at least one polar functional group selected from the group consisting of amide groups, imide groups, hydroxyl groups, carboxyl groups, sulfonic acid groups, phosphate groups, amino groups, and cyano groups, and the concentration of the polar functional group is 0.1 mmol / g or more and 8.5 mmol / g or less.

5. The carbon nanotube dispersion paste according to claim 1 or 2, wherein the water content of N-methyl-2-pyrrolidone (C) is 10,000 ppm or less.

6. A carbon nanotube dispersion paste according to claim 1 or 2, comprising a polyvinylidene fluoride resin (D).

7. The carbon nanotube dispersion paste according to claim 1 or 2, comprising a highly polar, low molecular weight component (E).

8. The carbon nanotube dispersion paste according to claim 1 or 2, wherein the water content is 10,000 ppm or less.

9. A composite paste for lithium-ion secondary batteries comprising a dispersion resin (A), carbon nanotubes (B), N-methyl-2-pyrrolidone (C), polyvinylidene fluoride resin (D), and electrode active material (F), wherein the dispersion term δD of the Hansen solubility parameter of the dispersion resin (A) is 16.35 or higher, and the Ra of the dispersion resin (A) for N-methyl-2-pyrrolidone (C), based on the Hansen solubility parameter, is 10.5 or lower.

10. An electrode layer for a non-aqueous electrolyte lithium-ion secondary battery, obtained by coating a lithium-ion secondary battery composite paste according to claim 9 onto a current collector.

11. An electrode for a non-aqueous electrolyte lithium-ion secondary battery, wherein an electrode insulating portion is provided at the end or upper layer of the electrode layer for a non-aqueous electrolyte lithium-ion secondary battery according to claim 10.

12. A non-aqueous electrolyte lithium-ion secondary battery comprising at least a positive electrode, a negative electrode, a non-aqueous electrolyte, and a separator, each having an electrode layer for a non-aqueous electrolyte lithium-ion secondary battery as described in claim 11.

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