Material for forming nonaqueous secondary battery electrode, binder composition for nonaqueous secondary battery electrode, method for producing material for forming nonaqueous secondary battery electrode, composition for nonaqueous secondary battery electrode, composition for conductive substrate coating, current collector, nonaqueous secondary battery electrode, and nonaqueous secondary battery

Abstract

Provided is a material for forming a nonaqueous secondary battery electrode, the material having excellent durability to an electrolytic solution (electrolytic solution resistance) and film formability and being capable of forming a secondary battery having excellent battery characteristics such as coulombic efficiency and capacity retention rate. Specifically provided is a material for forming a nonaqueous secondary battery electrode, the material containing core-shell type particles (A) having a shell part comprising a polymer (a1) and a core part comprising a polymer (a2), and an aqueous medium (B), wherein: the polymer (a1) contains a structural unit derived from a reactive emulsifying agent, a structural unit derived from a vinyl monomer having an acidic group, and a structural unit derived from a (meth)acrylic acid ester monomer; and the polymer (a2) contains a structural unit derived from a vinyl monomer having a crosslinkable reactive group and a structural unit derived from an aromatic vinyl monomer.

Description

Materials for forming electrodes in non-aqueous secondary batteries, binder compositions for non-aqueous secondary battery electrodes, methods for manufacturing materials for forming non-aqueous secondary battery electrodes, compositions for non-aqueous secondary battery electrodes, compositions for coating conductive substrates, current collectors, non-aqueous secondary battery electrodes, and non-aqueous secondary batteries

[0001] The present invention relates to a material for forming electrodes for non-aqueous secondary batteries, a binder composition for non-aqueous secondary battery electrodes, a method for producing a material for forming non-aqueous secondary battery electrodes, a composition for non-aqueous secondary battery electrodes, a composition for coating a conductive substrate, a current collector, a non-aqueous secondary battery electrode, and a non-aqueous secondary battery.

[0002] Non-aqueous secondary batteries (non-aqueous electrolyte secondary batteries), such as lithium-ion secondary batteries, are rapidly being deployed in hybrid vehicles, electric vehicles, and home energy storage systems, leveraging their high energy density and rechargeable nature, thus expanding their range of applications. In recent years, with the advancement of high performance and miniaturization of various portable electronic and communication devices, there has been a growing demand for secondary batteries that are small, lightweight, have higher capacity, and exhibit further improvements in various battery characteristics such as cycle characteristics and discharge rate characteristics. To further enhance the performance of non-aqueous secondary batteries, improvements to various battery components, such as electrodes, are being considered. Electrodes for non-aqueous secondary batteries typically comprise a current collector and an electrode material layer formed on the current collector. This electrode material layer is formed using a slurry-like electrode composition, for example, in which an active material (negative electrode active material or positive electrode active material) and a composition containing a binder (binding agent) are dispersed in a dispersion medium. In the negative electrode of lithium-ion secondary batteries, styrene-butadiene copolymer (SBR) is commonly used as the binder component. However, with SBR-based binders, the bonding properties between the negative electrode active materials and between the negative electrode active materials and the current collector are not always sufficient. As a result, when producing a negative electrode with a small amount of binder, there is a problem in which some of the negative electrode active materials peel off during the process of cutting the current collector. Acrylic emulsion (AcEm) is also used in some cases as a binder composition because of its excellent heat resistance and mechanical properties. However, while SBR has excellent electrolyte resistance due to its hydrophobic resin skeleton, AcEm has a problem in that it has high affinity for electrolytes due to its ester group resin skeleton and therefore has poor electrolyte resistance.

[0003] To address these problems, for example, Patent Document 1 proposes using an aqueous emulsion obtained by emulsion polymerization of an ethylenically unsaturated monomer in the presence of a surfactant, containing 15 to 70% by mass of styrene, 0.1 to 10% by mass of an ethylenically unsaturated carboxylic acid ester having polar groups, 25 to 80% by mass of other ethylenically unsaturated carboxylic acid esters, an ethylenically unsaturated carboxylic acid, and 0.1 to 3% by mass of an internal crosslinking agent as essential components relative to the total ethylenically unsaturated monomer, as a binder for lithium-ion secondary battery electrodes. In the binder of Patent Document 1, it is stated that electrolyte resistance is achieved by a crosslinking structure formed throughout the binder particles. Furthermore, Patent Document 2 proposes a binder for secondary battery electrodes containing a copolymer latex obtained by emulsion polymerization of a monomer composition comprising 60 to 94.8% by weight of an unsaturated carboxylic acid alkyl ester monomer, 0.1 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer containing a dicarboxylic acid, 5 to 20% by weight of an alkenyl aromatic monomer, and 0.1 to 10% by weight of other monomers copolymerizable with these (excluding cyano group-containing vinyl monomers, the aforementioned unsaturated carboxylic acid alkyl ester monomers, the aforementioned ethylenically unsaturated carboxylic acid monomers, and the aforementioned alkenyl aromatic monomers). The binder in Patent Document 2 is said to have excellent electrolyte resistance and improved bonding strength of the electrode coating layer because it does not contain cyano groups, which are easily soluble in electrolytes.

[0004] On the other hand, polyvinylidene fluoride (PVDF) is commonly used as a binder component in the positive electrode of lithium-ion secondary batteries. However, dissolving PVDF requires N-methyl-2-pyrrolidone (NMP) as a solvent, which presents challenges in terms of environmental impact. Furthermore, PVDF swells and becomes wet in the electrolyte at high temperatures above 50°C, weakening its bonding strength and increasing electrode resistance, resulting in poor high-temperature durability. In addition, the bonding properties between positive electrode active materials and between positive electrode active materials and current collectors are not always sufficient. To address these problems, SBR and acrylic emulsions are being considered as alternatives to PVDF. For example, Patent Document 3 proposes a binder for secondary battery electrodes obtained by polymerizing a monomer component (with a total monomer component of 100 parts by mass) containing (a1) an aromatic vinyl compound, 20 to 50 parts by mass of (a2) a conjugated diene compound, (a3) ​​a (meth)acrylic acid ester compound, and (a4) an ethylenically unsaturated carboxylic acid monomer, wherein the polymer containing constituent units derived from (a3) ​​(meth)acrylic acid ester compounds is polymerized by polymerizing a monomer component (with a total monomer component of 100 parts by mass). Patent Document 4 also proposes a binder for secondary battery electrodes containing a diene polymer in which (A) polymer particles have repeating units Mc derived from an unsaturated carboxylic acid, repeating units Md derived from a conjugated diene compound, and repeating units Me derived from an aromatic vinyl.

[0005] Furthermore, in lithium-ion secondary batteries, aluminum foil is generally used as the conductive substrate for the positive electrode and copper foil for the negative electrode. However, aluminum foil has the problem of poor adhesion to the electrode material layer (positive electrode active material layer) and high contact resistance. Therefore, coating the aluminum foil with a carbon coating layer acts as an adhesive between the aluminum foil and the electrode material layer, increasing adhesion, lowering contact resistance, and improving initial efficiency and retention rate. Examples of binders used in such carbon coating layers include PVDF, SBR, and CMC (carboxymethylcellulose). For example, Patent Document 5 proposes a carbon coating layer consisting of a mixture of carbon powder and PVDF.

[0006] Japanese Patent No. 5701519, Japanese Patent No. 5809636, Japanese Unexamined Patent Publication No. 2015-005523, Japanese Unexamined Patent Publication No. 2016-072235, Japanese Unexamined Patent Publication No. 2000-011991

[0007] In the binder described in Patent Document 1, a cross-linking structure is formed throughout the binder particles, making it difficult for the binder particles to fuse together. This results in insufficient bonding between the negative electrode active materials and between the negative electrode active materials and the current collector. Furthermore, while the binder described in Patent Document 2 attempts to improve electrolyte resistance by omitting cyano groups, which are easily soluble in electrolytes, simply omitting cyano groups is insufficient to achieve electrolyte resistance. Moreover, cyano groups have a high dielectric constant, which can be advantageous for lithium ion conductivity. The binders described in Patent Documents 3 and 4 also suffer from insufficient bonding between the active materials and between the active materials and the current collector. Patent Document 5 discloses a carbon coating layer that improves the adhesion between aluminum foil and the electrode material layer. However, the PVDF used in Patent Document 5 belongs to the category of solvent-based binders and uses N-methyl-2-prolidone (NMP) solvent, which is not only expensive but also environmentally unfriendly. Furthermore, Patent Document 5 mentions the use of SBR as a binder for the carbon coating layer, and points out that SBR belongs to the category of aqueous binders, and when used in carbon-coated aluminum foil, it has the disadvantage of low adhesive strength. Therefore, there is a strong demand for an electrode binder that has excellent electrolyte resistance and excellent bonding strength, and a binder for the conductive substrate coating layer (carbon coating layer) of a current collector that is environmentally friendly and can firmly bond the current collector and the electrode material layer. The present inventors have investigated an acrylic emulsion-based electrode forming material that has excellent electrolyte resistance and excellent film-forming properties such as bonding between active materials (negative electrode active material or positive electrode active material) and bonding between active materials and current collectors, as a binder (binder particles).As a result, we found that using core-shell type particles (A), which have a shell portion made of polymer (a1) containing structural units derived from a reactive emulsifier, an acidic vinyl monomer, and a (meth)acrylic acid ester monomer, and a core portion made of polymer (a2) containing structural units derived from a crosslinkable reactive vinyl monomer and an aromatic vinyl monomer, as an electrode binder composition, exhibits excellent electrolyte resistance and film-forming properties, and is effective in improving battery characteristics such as charge-discharge efficiency and capacity retention rate of secondary batteries equipped with electrodes formed using such electrode binder composition. Furthermore, we found that using such electrode-forming material as a binder to coat the surface of a conductive substrate that serves as a current collector with a layer containing a conductive material can increase the adhesion strength between the conductive substrate and the electrode material layer, and is inexpensive and reduces environmental impact. Based on these findings, we completed the present invention. The object of the present invention is to provide a non-aqueous secondary battery electrode forming material that can be applied as a binder composition for non-aqueous secondary battery electrodes capable of forming a secondary battery with excellent durability to electrolytes (electrolyte resistance) and film-forming properties, and excellent battery characteristics such as charge-discharge efficiency and capacity retention rate. The object of the present invention is also to provide a method for producing such an electrode forming material, a non-aqueous secondary battery electrode composition containing such an electrode forming material, a non-aqueous secondary battery electrode containing the electrode composition, and a non-aqueous secondary battery having the electrode. Another object of the present invention is to provide a conductive substrate coating composition containing such an electrode forming material, a current collector having a coating layer formed of the conductive substrate coating composition, an electrode equipped with the current collector, and a non-aqueous secondary battery equipped with the electrode.

[0008] The present invention has the following embodiments: [1] A material for forming electrodes for a non-aqueous secondary battery, comprising core-shell type particles (A) having a shell portion made of polymer (a1) and a core portion made of polymer (a2), and an aqueous medium (B), wherein the polymer (a1) contains structural units derived from a reactive emulsifier, structural units derived from a vinyl monomer having an acidic group, and structural units derived from a (meth)acrylic acid ester monomer, and the polymer (a2) contains structural units derived from a vinyl monomer having a crosslinkable reactive group and structural units derived from an aromatic vinyl monomer. [2] The material for forming electrodes for a non-aqueous secondary battery according to [1], wherein the reactive emulsifier is an emulsifier having an ethylenically unsaturated group. [3] The material for forming electrodes for a non-aqueous secondary battery according to [1], wherein the content of structural units derived from the reactive emulsifier relative to the total amount obtained by excluding the structural units derived from the reactive emulsifier from the units constituting the polymer (a1) is 0.01% by mass or more and 3% by mass or less. [4] The non-aqueous secondary battery electrode forming material according to [1], wherein the content of structural units derived from the acidic vinyl monomer, relative to the total amount obtained by excluding the structural units derived from the reactive emulsifier from the units constituting the polymer (a1), is 0.1% by mass or more and 10% by mass or less. [5] The non-aqueous secondary battery electrode forming material according to [1], wherein the polymer (a1) further contains structural units derived from an aromatic vinyl monomer. [6] The non-aqueous secondary battery electrode forming material according to [1], wherein the polymer (a1) further contains structural units derived from a vinyl monomer having an amide group. [7] The non-aqueous secondary battery electrode forming material according to [1], wherein the crosslinkable reactive group is at least one selected from an ethylenically unsaturated group, a monofunctional or polyfunctional alkoxysilyl group, a methylol group, and an alkyloxymethyl group. [8] The non-aqueous secondary battery electrode forming material according to [1], wherein the content of structural units derived from the vinyl monomer having the crosslinkable reactive group relative to the total amount of units constituting the polymer (a2) is 0.1% by mass or more and 10% by mass or less. [9] The non-aqueous secondary battery electrode forming material according to [1], wherein the polymer (a2) further contains structural units derived from the (meth)acrylic acid ester monomer.

[10] The non-aqueous secondary battery electrode forming material according to [1], wherein the polymer (a2) further contains structural units derived from a vinyl monomer having a cyano group.

[11] The non-aqueous secondary battery electrode forming material according to [1], wherein the polymer (a2) does not contain structural units derived from a vinyl monomer having an acidic group.

[12] The non-aqueous secondary battery electrode forming material according to [1], wherein the polymer (a2) does not contain structural units derived from a fluorine-containing monomer.

[13] The non-aqueous secondary battery electrode forming material according to any one of [1] to

[12] , which is a binder composition for non-aqueous secondary battery electrodes.

[14] A method for producing a material for forming an electrode for a non-aqueous secondary battery, comprising a core-shell particle (A) having a shell portion made of polymer (a1) and a core portion made of polymer (a2), and an aqueous medium (B), the method comprising: a shell portion forming step of polymerizing a vinyl monomer having an acidic group and a (meth)acrylic acid ester monomer in the aqueous medium (B) in the presence of a reactive emulsifier to form polymer particles that will become the shell portion made of polymer (a1); and a core portion forming step of polymerizing a vinyl monomer having a crosslinkable reactive group and an aromatic vinyl monomer using the polymer particles as a reaction field to form the core portion made of polymer (a2) inside the polymer particles.

[15] A composition for a non-aqueous secondary battery electrode, comprising an active material and the binder composition for a non-aqueous secondary battery electrode of

[13] .

[16] A non-aqueous secondary battery electrode comprising an electrode material layer formed using the composition for a non-aqueous secondary battery electrode of

[15] .

[17] A non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein at least one of the positive electrode and the negative electrode is the non-aqueous secondary battery electrode of

[16] .

[18] A composition for coating a conductive substrate, comprising a conductive material and the non-aqueous secondary battery electrode forming materials of [1] to

[12] .

[19] A current collector having a coating layer formed of the conductive substrate coating composition of

[18] on one or both sides of a sheet-like conductive substrate.

[20] A non-aqueous secondary battery electrode comprising the current collector of

[19] .

[21] A non-aqueous secondary battery comprising the non-aqueous secondary battery electrode of

[20] .

[0009] The present invention provides a binder composition for non-aqueous secondary battery electrodes that can form a secondary battery with excellent durability to electrolytes (electrolyte resistance) and film-forming properties, as well as excellent battery characteristics such as charge-discharge efficiency and capacity retention rate; a binder composition for non-aqueous secondary battery electrodes containing such an electrode composition; a non-aqueous secondary battery electrode containing such an electrode composition; and a non-aqueous secondary battery having such an electrode. Furthermore, the present invention provides a method for manufacturing the non-aqueous secondary battery electrode material that can stably produce the non-aqueous secondary battery electrode material having the above-mentioned properties. In addition, the present invention provides a conductive substrate coating composition that can increase the adhesion strength between the conductive substrate and the electrode material layer, and can form an electrode with excellent battery characteristics and electrolyte resistance; a current collector having a coating layer formed with such a conductive substrate coating composition; an electrode equipped with such a current collector; and a non-aqueous secondary battery equipped with such an electrode.

[0010] Embodiments of the present invention will be described in detail below. In this specification, numerical ranges indicated using "~" indicate a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. 1. Non-aqueous secondary battery electrode formation material The present invention is a non-aqueous secondary battery electrode formation material containing core-shell type particles (A) having a shell portion made of polymer (a1) and a core portion made of polymer (a2), and an aqueous medium (B), wherein the polymer (a1) contains structural units derived from a reactive emulsifier, structural units derived from a vinyl monomer having an acidic group, and structural units derived from a (meth)acrylic acid ester monomer, and the polymer (a2) contains structural units derived from a vinyl monomer having a crosslinkable reactive group and structural units derived from an aromatic vinyl monomer. The electrode-forming material of the present invention is an aqueous binder composition in which a binder (binding agent) is dispersed in an aqueous medium (B), and is useful as a binder composition for electrodes of non-aqueous secondary batteries, particularly in the electrode material layer. Furthermore, it may optionally contain other components commonly used in the field of non-aqueous secondary batteries. First, the constituent components of the electrode-forming material of the present invention will be described.

[0011] <Core-shell type particles (A)> The electrode-forming material of the present invention contains core-shell type particles (A) having a shell portion made of polymer (a1) containing structural units derived from a reactive emulsifier, a vinyl monomer having an acidic group, and a (meth)acrylic acid ester monomer, respectively, and a core portion made of polymer (a2) containing structural units derived from a vinyl monomer having a crosslinkable reactive group and an aromatic vinyl monomer, respectively. The polymer (a1) constituting the shell portion exhibits excellent binding properties (film-forming properties) to the core-shell type particles (A), while the polymer (a2) constituting the core portion has a crosslinked structure, giving the core-shell type particles (A) excellent durability (electrolyte resistance).

[0012] As described later, core-shell type particles (A) are obtained by polymerizing a vinyl monomer having an acidic group and a (meth)acrylic acid ester monomer in an aqueous medium (B) in the presence of a reactive emulsifier to form polymer particles that form a shell portion consisting of polymer (a1). Then, a vinyl monomer having a crosslinkable reactive group and an aromatic vinyl monomer are polymerized using the polymer particles as a reaction site to form a core portion consisting of polymer (a2) inside the polymer particles. The reactive emulsifier, upon reaction, is incorporated into the shell portion as a component of polymer (a1), becoming a hydrophilic group of the polymer that forms the shell portion, and losing its function as a surfactant. Therefore, the polymerization of the core portion can be described as soap-free polymerization carried out in the absence of surfactants. In the formation process of the core-shell particle (A) described above, the hydrophobic monomers (vinyl monomers and aromatic vinyl monomers having crosslinkable reactive groups) that are to become the core portion (polymer (a2)) penetrate into the interior of the hydrophilic polymer particles (polymer (a1)) formed by the reaction of the reactive emulsifier, and polymerize inside the polymer particles to form the core-shell particle (A). Core-shell particles obtained in this way, by polymerizing hydrophobic monomers inside the hydrophilic polymer particles that form the shell portion to form the core portion, are called inverted core-shell particles.

[0013] Core-shell particles (A) formed through a reverse-phase core-shell process using a reactive emulsifier ensure that each particle reliably possesses a core-shell structure. In contrast, when a normal-phase core-shell process is used, in which a shell portion is formed on the surface of polymer particles that form the core portion using a non-reactive emulsifier, particles formed solely of the polymer components constituting the shell are easily generated as by-products in addition to core-shell particles. From this perspective, the electrode-forming material of the present invention is advantageous in that each core-shell particle (A) possesses stable shell characteristics (film-forming ability) and core characteristics (electrolyte resistance). Furthermore, as described above, since the polymer (a1) that forms the shell portion of the core-shell particle (A) has hydrophilic groups derived from the reactive emulsifier, the core-shell particle (A) has high affinity for the aqueous medium (B) and can exist stably in the aqueous medium (B). Moreover, in the core-shell particle (A), the polymer (a1) and polymer (a2) are fused within the particle, resulting in separation at the nm size. Polymers (a1) and (a2) are phase-separated at a size sufficiently smaller than the size (μm size) of the negative electrode active material or positive electrode active material (hereinafter also simply referred to as "active material"). Therefore, for all types of active materials, the properties of both the core and shell portions can be expressed, and uniform performance can be achieved throughout the electrode. In contrast, when polymers (a1) and (a2) are simply blended (mixed), polymers (a1) and (a2) separate at the particle size level (μm size). As a result, depending on the active material used, products with poor electrolyte resistance or poor binding properties may occur, leading to deterioration of the overall performance of the electrode or non-uniform performance. Therefore, the electrode-forming material of the present invention, by using core-shell type particles (A) as a binder, exhibits excellent electrolyte resistance and film-forming properties. Furthermore, it is possible to improve battery characteristics such as charge-discharge efficiency and capacity retention rate of secondary batteries equipped with electrodes formed using such electrode-forming material.

[0014] (Shell part) The shell part is composed of a polymer (a1) containing structural units derived from a reactive emulsifier, a vinyl monomer having an acidic group, and a (meth)acrylate monomer, respectively. The reactive emulsifier used for forming the shell part (polymer (a1)) is an emulsifier having a polymerizable ethylenically unsaturated group such as a vinyl group and a hydrophilic group in the molecule. While a normal non-reactive emulsifier only adsorbs on the surface of the formed particles, the reactive emulsifier is incorporated into the polymer (a1) as a component of the copolymer during the polymerization process of the polymer (a1). Therefore, it has the characteristics that the emulsifier does not bleed out (free) from the polymer (a1) in the aqueous medium (B), or it is difficult to bleed out. In the electrode-forming material of the present invention, since the bleeding out of the reactive emulsifier from the core-shell type particles (A) can be prevented or suppressed, an electrode excellent in peel strength between the formed electrode material layer and the current collector can be obtained. Further, since the shell part (polymer (a1)) has a hydrophilic group derived from the reactive emulsifier, it has a high affinity with the aqueous medium (B), and the core-shell type particles (A) can stably exist in the aqueous medium (B).

[0015] As the reactive emulsifier, for example, emulsifiers represented by General Formulas (1) to (5) can be used.

[0016] General Formula (1) [Chemical Formula 1] In General Formula (1), R is an alkyl group, and m is an integer of 10 to 40.

[0017] General Formula (2) [Chemical Formula 2] In General Formula (2), x is an integer of 10 to 12, and y is an integer of 10 to 40.

[0018] General Formula (3) [Chemical Formula 3] In General Formula (3), R is an alkyl group, and M is NH ４ or Na.

[0019] General Formula (4) [Chemical Formula 4] In General Formula (4), R is an alkyl group.

[0020] General Formula (5) [Chemical Formula 5] In General Formula (5), X is a hydrogen atom or SO ３NH ４ Here, m is an integer between 1 and 4 (inclusive), and n is an integer between 5 and 40 (inclusive). X is SO ３ NH ４ It is preferable that m is between 1 and 3. It is preferable that n is between 8 and 40, more preferably between 8 and 25, and even more preferably between 8 and 15.

[0021] Specific examples of reactive emulsifiers include alkyl ether type (commercial products such as Adekarya Soap SR-10, SR-10N, SR-20N from ADEKA Corporation, Aqualon KH-05, KH-10, KH-20 from Daiichi Kogyo Seiyaku Co., Ltd., and Latemul PD-104 from Kao Corporation), sulfosuccinate ester type (commercial products such as Latemul S-120, S-120A, S-180P, S-180A from Kao Corporation, and Eleminol JS-2 from Sanyo Chemical Industries, Ltd.), alkylphenyl ether type or alkylphenyl ester type (commercial products such as Aqualon AR-10, AR-2 from Daiichi Kogyo Seiyaku Co., Ltd.) Examples include 0, H-2855A, H-3855B, H-3855C, H-3856, HS-05, HS-10, HS-20, HS-30, Adekarya Soap SDX-222, SDX-223, SDX-232, SDX-233, SDX-259, SE-10N, SE-20N, etc. manufactured by ADEKA Corporation), (meth)acrylate sulfate ester type (commercial products include, for example, Antox MS-60, MS-2N manufactured by Nippon Emulsifier Co., Ltd., and Eleminor RS-30 manufactured by Sanyo Chemical Industries, Ltd.), phosphate ester type (commercial products include, for example, H-3330PL manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and Adekarya Soap PP-70 manufactured by ADEKA Corporation). These reactive emulsifiers may be used individually or in combination of two or more types. Furthermore, the content of structural units derived from the reactive emulsifier, relative to the total amount obtained by excluding the structural units derived from the reactive emulsifier from the units constituting the polymer (a1), is preferably 0.01% by mass or more and 3% by mass or less. If the content of structural units derived from the reactive emulsifier is within the above range, the core-shell type particles (A) can exist more stably in the aqueous medium (B), and an electrode with better peel strength between the formed electrode material layer and the current collector can be obtained. In addition, as will be described later, when forming the shell portion (polymer a1), a non-reactive emulsifier may be used in combination with the reactive emulsifier, so that the shell portion (polymer a1) contains a non-reactive emulsifier. In that case, the content of the non-reactive emulsifier is preferably 1 / 2 or less, more preferably 1 / 5, and even more preferably 1 / 10 or less of the content of the reactive emulsifier.

[0022] The vinyl monomer having acidic groups is used in the formation of the shell portion (polymer (a1)) to improve the particle stability of the core-shell type particles (A) in the aqueous medium (B), and to promote the fusion of the core-shell type particles (A) with each other through hydrogen bonding between acidic groups and between acidic groups and other functional groups in the formed electrode material layer, thereby improving the film-forming properties of the core-shell type particles (A). Examples of vinyl monomers having acidic groups include monocarboxylic acids and dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, as well as their anhydrides. One type of vinyl monomer having acidic groups may be used alone, or two or more types may be used in combination. Among these, the use of acrylic acid, methacrylic acid, or itaconic acid is preferred. Furthermore, it is preferable that the content of structural units derived from the vinyl monomer having acidic groups, relative to the total amount of structural units derived from the reactive emulsifier excluding the structural units derived from the reactive emulsifier from the units constituting the polymer (a1), be 0.1% by mass or more and 10% by mass or less. If the content of structural units derived from vinyl monomers having acidic groups is within the above range, the core-shell particles (A) can exist more stably in the aqueous medium (B), and the fusion of the core-shell particles (A) with each other in the formed electrode material layer can be promoted, further improving the film-forming properties of the core-shell particles (A).

[0023] (Meth)acrylic acid monomers are used to form the shell portion (polymer (a1)) and improve the film-forming properties of core-shell type particles (A). Examples of (meth)acrylic acid monomers include alkyl acrylates such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, butyl acrylate, t-butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, and stearyl acrylate; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate Examples include alkyl methacrylates such as ropyl, n-butyl methacrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate; and hydroxyl group-containing (meth)acrylic acid ester monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. These (meth)acrylic acid ester monomers may be used individually or in combination of two or more. Among these, (meth)acrylic acid ester monomers with 6 to 16 carbon atoms are preferred. Furthermore, it is preferable to use 2-ethylhexyl acrylate, butyl acrylate, or methyl methacrylate. Furthermore, the content of structural units derived from the (meth)acrylic acid ester monomer relative to the total amount of structural units derived from the reactive emulsifier from the units constituting the polymer (a1) is not particularly limited, but can be 5% by mass or more and 100% by mass or less. The lower limit of the content of structural units derived from the (meth)acrylic acid ester monomer can be 5% by mass or more, 10% by mass or more, 20% by mass or more, 30% by mass or more, or 40% by mass or more.Furthermore, the upper limit of the content of structural units derived from the above (meth)acrylic acid ester monomer can be 100% by mass or less, 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0024] Furthermore, the polymer (a1) may further contain structural units derived from aromatic vinyl monomers and structural units derived from vinyl monomers having amide groups, in addition to structural units derived from each of the above components. The aromatic vinyl monomers are used in the formation of the shell portion (polymer (a1)) to improve the electrolyte resistance and film-forming properties of the core-shell type particles (A). Examples of aromatic vinyl monomers include styrene, α-methylstyrene, and vinyltoluene. These aromatic vinyl monomers may be used individually or in combination of two or more. Among these, styrene is preferred. The content of structural units derived from aromatic vinyl monomers relative to the total amount of structural units derived from the reactive emulsifier from the units constituting the polymer (a1) is not particularly limited, but can be 5% by mass or more and 95% by mass or less.

[0025] When a vinyl monomer containing amide groups is used to form the shell portion (polymer (a1)), it promotes the fusion of core-shell type particles (A) in the formed electrode material layer through hydrogen bonding between amide groups and between amide groups and other functional groups, thereby improving the film-forming properties of the core-shell type particles (A). Furthermore, by using a vinyl monomer containing amide groups to form the shell portion (polymer (a1)), the stability of the polymer particles in which the amide groups form the shell portion is improved in the reverse-phase core-shell process, resulting in the stable progression of polymerization of the core portion. Examples of vinyl monomers having an amide group include (meth)acrylamide; alkylol (meth)acrylamide compounds such as N-methylolacrylamide, N,N-di(methylol)acrylamide, and N-methylol-N-methoxymethyl(meth)acrylamide; monoalkoxy (meth)acrylamide compounds such as N-methoxymethyl-(meth)acrylamide, N-ethoxymethyl-(meth)acrylamide, N-propoxymethyl-(meth)acrylamide, N-butoxymethyl-(meth)acrylamide, and N-pentoxymethyl-(meth)acrylamide; and N,N-di(methoxymethyl)acrylamide, N-ethoxymethyl-N-methoxymethylmethacrylamide, N,N-di(ethoxymethyl)acrylamide, and N-ethoxymethyl-N-propoxymethylmethacrylamide. Examples include dialkoxy(meth)acrylamide compounds such as N,N-di(propoxymethyl)acrylamide, N-butoxymethyl-N-(propoxymethyl)methacrylamide, N,N-di(butoxymethyl)acrylamide, N-butoxymethyl-N-(methoxymethyl)methacrylamide, N,N-di(pentoxymethyl)acrylamide, and N-methoxymethyl-N-(pentoxymethyl)methacrylamide; dialkylamino(meth)acrylamide compounds such as N,N-dimethylaminopropylacrylamide and N,N-diethylaminopropylacrylamide; dialkyl(meth)acrylamide compounds such as N,N-dimethylacrylamide and N,N-diethylacrylamide; and keto group-containing (meth)acrylamide compounds such as diacetone(meth)acrylamide.These vinyl monomers having amide groups may be used individually or in combination of two or more. Among these, acrylamide, dimethylacrylamide, N-methylolacrylamide, or N-methylolmethacrylamide is preferred. Furthermore, it is preferable that the content of structural units derived from the vinyl monomer having amide groups, relative to the total amount of structural units derived from the reactive emulsifier from the units constituting the polymer (a1), is 0.1% by mass or more and 10% by mass or less. If the content of structural units derived from the vinyl monomer having amide groups is within the above range, the fusion of core-shell type particles (A) in the formed electrode material layer can be promoted, further improving the film-forming properties of the core-shell type particles (A).

[0026] (Core) The core is composed of a polymer (a2) containing structural units derived from a vinyl monomer having a crosslinkable reactive group and an aromatic vinyl monomer, respectively. The vinyl monomer having a crosslinkable reactive group used to form the core (polymer (a2)) forms a crosslinked structure in polymer (a2). This gives the core-shell particle (A) excellent resistance to electrolytes (electrolyte resistance). Furthermore, as mentioned above, in the core-shell particle (A), polymer (a1) and polymer (a2) are fused within the particle and are separated at the nm size. In such a core-shell particle (A), even though only the core has a crosslinked structure, the core-shell particle (A) as a whole can exhibit the characteristics of both the core and the shell, resulting in a core-shell particle (A) with excellent electrolyte resistance and film-forming properties.

[0027] A vinyl monomer having a crosslinkable reactive group preferably has at least one selected from an ethylenically unsaturated group, a monofunctional or polyfunctional alkoxysilyl group, a methylol group, and an alkyloxymethyl group as the crosslinkable reactive group. Examples of vinyl monomers having an ethylenically unsaturated group as a crosslinkable reactive group include divinyl compounds such as divinylbenzene and divinyl adipate; polyfunctional (meth)acrylic acid esters such as ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, 1,1,1-trishydroxymethylethane diacrylic acid, 1,1,1-trishydroxymethylethane triacrylic acid, and 1,1,1-trishydroxymethylpropanetriacrylic acid; allyl (meth)acrylate, 1-methylallyl (meth)acrylate, 2-methylallyl (meth)acrylate, 1-butenyl (meth)acrylate, and 2-butenyl (meth)acrylate. Examples include ethylenically unsaturated group-containing (meth)acrylic acid esters such as 3-butenyl (meth)acrylate, 1,3-methyl-3-butenyl (meth)acrylate, 2-chlorallyl (meth)acrylate, 3-chlorallyl (meth)acrylate, o-allylphenyl (meth)acrylate, 2-(allyloxy)ethyl (meth)acrylate, allyl lactyl (meth)acrylate, citronellyl (meth)acrylate, geranyl (meth)acrylate, rhodinyl (meth)acrylate, cinnamyl (meth)acrylate, diallyl maleate, diallyluitaconic acid, vinyl (meth)acrylate, vinyl crotate, vinyl oleate, vinyl linolenate, and 2-(2'-vinyloxyethoxy)ethyl (meth)acrylate; and diallyls such as diallyl isophthalate, diallyl phthalate, and diallyl maleate. These vinyl monomers having ethylenically unsaturated groups as crosslinking reactive groups may be used individually or in combination of two or more. Among these, divinylbenzene or ethylene glycol diacrylate is preferred.

[0028] Examples of vinyl monomers having monofunctional or polyfunctional alkoxysilyl groups as crosslinking reactive groups include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropyltributoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-acryloxymethyltrimethoxysilane, vinyltrimethoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, and the like. These vinyl monomers having monofunctional or polyfunctional alkoxysilyl groups as crosslinking reactive groups may be used individually or in combination of two or more. Among these, it is preferable to use γ-methacryloxypropyltrimethoxysilane (3-(trimethoxysilyl)propyl methacrylate).

[0029] Examples of vinyl monomers having a methylol group as a crosslinking reactive group include N-methylol(meth)acrylamide and N,N-di(methylol)acrylamide. These vinyl monomers having a methylol group as a crosslinking reactive group may be used individually or in combination of two or more. Among these, N-methylol(meth)acrylamide is preferred. Examples of vinyl monomers having an alkyloxymethyl group as a crosslinking reactive group include N-methoxymethyl(meth)acrylamide and N-butoxymethyl(meth)acrylamide. These vinyl monomers having an alkyloxymethyl group as a crosslinking reactive group may be used individually or in combination of two or more.

[0030] Furthermore, it is preferable that the content of structural units derived from vinyl monomers having crosslinkable reactive groups relative to the total amount of units constituting the polymer (a2) is 0.1% by mass or more and 10% by mass or less. If the content of structural units derived from vinyl monomers having crosslinkable reactive groups is within the above range, the electrolyte resistance of core-shell type particles (A) can be further improved.

[0031] The aromatic vinyl monomer is used in the formation of the core portion (polymer (a2)) to improve the electrolyte resistance of the core-shell type particle (A). As such, the various aromatic vinyl monomers mentioned above that can be used in the formation of polymer (a1) can be used, and styrene is particularly preferred. Furthermore, the content of structural units derived from the aromatic vinyl monomer relative to the total amount of units constituting polymer (a2) is preferably 10% by mass or more and 100% by mass or less. If the content of structural units derived from the aromatic vinyl monomer is within the above range, the electrolyte resistance of the core-shell type particle (A) can be further improved. The lower limit of the content of structural units derived from the aromatic vinyl monomer can be 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, and 90% by mass or more. Furthermore, the upper limit of the content of structural units derived from the aromatic vinyl monomer can be 100% by mass or less, 99.8% by mass or less, 99.5% by mass or less, 99.2% by mass or less, and 90% by mass or less.

[0032] Furthermore, polymer (a2) may further contain structural units derived from each of the above components, as well as structural units derived from (meth)acrylic acid ester monomers and structural units derived from vinyl monomers having cyano groups. The (meth)acrylic acid ester monomer is used in the formation of the core portion (polymer (a2)) to improve the film-forming properties of the core-shell type particles (A). As such (meth)acrylic acid ester monomers, the various (meth)acrylic acid ester monomers mentioned above that can be used in the formation of polymer (a1) can be used, and it is particularly preferable to use 2-ethylhexyl acrylate, butyl acrylate, methyl methacrylate, or 2-hydroxyethyl methacrylate. In addition, it is preferable that the content of structural units derived from (meth)acrylic acid ester monomers relative to the total amount of units constituting polymer (a2) be 5% by mass or more and 90% by mass or less. If the content of structural units derived from (meth)acrylic acid ester monomers is within the above range, the film-forming properties of the core-shell type particles (A) can be further improved.

[0033] When a vinyl monomer having a cyano group is used to form the core portion (polymer (a2)), the high dielectric constant of the cyano group improves the conductivity of lithium ions in the formed electrode, and as a result, the discharge capacity maintenance rate of the secondary battery equipped with such electrode is improved. Furthermore, since the structural units derived from the vinyl monomer having a cyano group are contained only in the polymer (a2) constituting the core portion, the vinyl monomer having a cyano group does not dissolve into the electrolyte, and the electrolyte resistance of the core-shell type particle (A) does not decrease. Examples of vinyl monomers having a cyano group include vinyl monomers having nitrile groups such as (meth)acrylonitrile, and the use of acrylonitrile is particularly preferred. Furthermore, the content of structural units derived from the vinyl monomer having a cyano group relative to the total amount of units constituting the polymer (a2) is preferably 0.1% by mass or more and 10% by mass or less. If the content of structural units derived from the vinyl monomer having a cyano group is within the above range, the conductivity of lithium ions in the formed electrode is further improved, and as a result, the discharge capacity maintenance rate of the secondary battery equipped with such electrode can be further improved.

[0034] Furthermore, it is preferable that polymer (a2) does not contain structural units derived from the aforementioned acidic vinyl monomer and structural units derived from fluorine-containing monomer as constituent components of polymer (a1). If polymer (a2) contains structural units derived from acidic vinyl monomer, it becomes disadvantageous in terms of fusion between core-shell particles (A) and peel strength between the electrode material layer and the current collector in the formed electrode material layer. Also, in the reverse-phase core-shell process, if the polymer (a2) that forms the core contains a vinyl monomer with an acidic group as a constituent monomer, it becomes difficult to balance the hydrophilicity between the polymer particles that form the shell and the constituent monomer of polymer (a2), making it difficult to form reverse-phase core-shell particles. Furthermore, if polymer (a2) contains structural units derived from fluorine-containing monomer, similarly to the above, it becomes disadvantageous in terms of fusion between core-shell particles (A) and peel strength between the electrode material layer and the current collector in the formed electrode material layer. Furthermore, in the reversed-phase core-shell process, if fluorine-containing monomers are included as constituent monomers in the polymer (a2) that forms the core, it becomes difficult to balance the hydrophilicity between the polymer particles that form the shell and the constituent monomers of the polymer (a2), making it difficult to form reversed-phase core-shell particles.

[0035] Furthermore, when the content of polymer (a1) in the core-shell type particle (A) is X [mass%] and the content of polymer (a2) in the core-shell type particle (A) is Y [mass%], it is preferable that X:Y be 5:95 to 99:1, and more preferably that X:Y be 10:90 to 95:5. The core-shell type particle (A) exhibits excellent binding properties (film-forming properties) due to the polymer (a1) constituting the shell portion, and excellent durability to electrolytes (electrolyte resistance) due to the polymer (a2) constituting the core portion. Therefore, depending on the type of material used, if the content of polymer (a1) in the core-shell type particle (A) is low, the shell properties (film-forming properties) may decrease, and if the content of polymer (a2) in the core-shell type particle (A) is low, the core properties (electrolyte resistance) may decrease. In contrast, if the content of polymer (a1) and polymer (a2) in the core-shell type particle (A) are within the above range, an electrode-forming material containing core-shell type particle (A) that achieves both excellent film-forming properties and electrolyte resistance can be obtained.

[0036] <Aqueous medium (B)> The aqueous medium (B) functions as a dispersion medium for the core-shell particles (A). Examples of aqueous mediums include water (distilled water, deionized water, tap water, etc.) and water to which various alcohols have been added. As described later, the electrode-forming material of the present invention is obtained by forming core-shell particles (A) in the aqueous medium (B) in the presence of a reactive emulsifier via a reversed-phase core-shell process. The liquid containing the core-shell particles (A) and aqueous medium (B) obtained in this way can be used as the electrode-forming material of the present invention as is, or it may be diluted with additional aqueous medium (B) as needed before being used as the electrode-forming material of the present invention. The content of core-shell particles (A) in the total electrode-forming material of the present invention is preferably in the range of 10 to 100% by mass.

[0037] The electrode-forming material of the present invention may further contain various additives as needed, such as other resins, surfactants, antioxidants, light stabilizers, plasticizers, viscosity modifiers, and organic or inorganic fillers, to the extent that they do not impair the effects of the present invention.

[0038] 2. Method for Manufacturing Materials for Forming Electrodes of Non-Aqueous Secondary Battery The present invention also relates to a method for manufacturing materials for forming electrodes of non-aqueous secondary battery, comprising a core-shell type particle (A) having a shell portion made of polymer (a1) and a core portion made of polymer (a2), and an aqueous medium (B), the method comprising: a shell portion forming step of polymerizing a vinyl monomer having an acidic group and a (meth)acrylic acid ester monomer in the aqueous medium (B) in the presence of a reactive emulsifier to form polymer particles that will become the shell portion made of polymer (a1); and a core portion forming step of polymerizing a vinyl monomer having a crosslinkable reactive group and an aromatic vinyl monomer using the polymer particles as a reaction field to form the core portion made of polymer (a2) inside the polymer particles. (Hereinafter also simply referred to as "the method for manufacturing electrodes of the present invention") The steps of the method for manufacturing electrodes of the present invention will be described below.

[0039] (Shell Formation Process) The shell formation process involves polymerizing a vinyl monomer having an acidic group and a (meth)acrylic acid ester monomer in an aqueous medium (B) in the presence of a reactive emulsifier to form polymer particles that will become a shell portion consisting of polymer (a1). The reactive emulsifier, the vinyl monomer having an acidic group, the (meth)acrylic acid ester monomer and the aqueous medium (B), as well as each of the components described later (aromatic vinyl monomer, vinyl monomer having an amide group, vinyl monomer having a crosslinkable reactive group, and vinyl monomer having a cyano group), are all the same as those described in the electrode forming material of the present invention. In addition to the reactive emulsifier, a non-reactive emulsifier may also be used in combination.

[0040] The reactive emulsifier, upon reaction, is incorporated into the shell portion as a component of the polymer (a1), becoming a hydrophilic group of the polymer that forms the shell portion, and losing its function as a surfactant. In addition to the above components, aromatic vinyl monomers and / or vinyl monomers having amide groups can be used as constituent monomers of the shell portion (polymer (a1)). In particular, by using vinyl monomers having amide groups, in the reversed-phase core-shell process, the amide groups improve the stability of the polymer particles that form the shell portion, and the polymerization of the core portion in the core portion formation process proceeds stably. The reactive emulsifier, vinyl monomer having acidic groups, (meth)acrylic acid ester monomer, and other monomers may be added directly to the aqueous medium (B), but it is preferable to prepare these components in advance as an emulsion in the aqueous medium and add this to the aqueous medium (B). By adding each monomer as an emulsion to the aqueous medium (B), polymer particles with a more uniform size are formed, and the properties of the formed core-shell type particles (A) are stabilized.

[0041] In this step, it is preferable to include a radical polymerization initiator. Examples of radical polymerization initiators include ammonium persulfate, potassium persulfate, hydrogen peroxide, and t-butyl hydroperoxide. The content of the radical polymerization initiator relative to the total amount of units constituting the polymer (a1) excluding structural units derived from the reactive emulsifier is preferably 0.01% by mass or more and 1% by mass or less. In addition, in this step, the polymerization temperature of each component should be equal to or higher than the polymerization initiation temperature of the radical polymerization initiator used. For example, when using ammonium persulfate as the radical polymerization initiator, the polymerization temperature should be approximately 60°C to 90°C. The polymerization time is not particularly limited, but is usually 2 to 24 hours.

[0042] (Core Formation Process) The core formation process involves polymerizing vinyl monomers and aromatic vinyl monomers having crosslinkable reactive groups using the polymer particles as a reaction site to form a core consisting of polymer (a2) inside the polymer particles. As mentioned above, in the shell formation process, the reactive emulsifier becomes a hydrophilic group of the polymer that will become the shell, and loses its function as a surfactant. Therefore, the polymerization that forms the core (polymer a2) in the core formation process can be described as soap-free polymerization, which is carried out in the absence of surfactants. The polymer particles that will become the shell have hydrophilic groups derived from the reactive emulsifier, which increases their hydrophilicity with respect to the vinyl monomers and aromatic vinyl monomers having crosslinkable reactive groups that are to become the core (polymer (a2)). As a result, the hydrophobic monomers that are to become the core (polymer (a2)) enter the interior of the polymer particles having hydrophilic groups (polymer (a1)) and polymerize inside the polymer particles, thereby forming a core-shell type particle (A) through a reversed-phase core-shell process.

[0043] Vinyl monomers having crosslinkable reactive groups, aromatic vinyl monomers, and other monomers may be added directly to the aqueous medium (B) in which the polymer particles are dispersed, or they may be added as an emulsion that has been emulsified in the aqueous medium beforehand, but it is preferable to add these monomers directly.

[0044] In this step, it is preferable to include a radical polymerization initiator. Various radical polymerization initiators as described above can be used. Furthermore, the content of the radical polymerization initiator relative to the total amount of units constituting the polymer (a2) is preferably 0.01% by mass or more and 1% by mass or less. Also, in this step, the polymerization temperature of each component should be equal to or higher than the polymerization initiation temperature of the radical polymerization initiator used. For example, when using ammonium persulfate as the radical polymerization initiator, the polymerization temperature should be approximately 60°C to 90°C. The polymerization time is not particularly limited, but is usually 2 to 24 hours.

[0045] 3. Compositions for Non-Aqueous Secondary Battery Electrodes The non-aqueous secondary battery electrode forming material of the present invention can be suitably used as an electrode binder composition, as described above. That is, the present invention also provides a non-aqueous secondary battery electrode composition (hereinafter simply referred to as "the electrode composition of the present invention") containing an active material (negative electrode active material or positive electrode active material) and the non-aqueous secondary battery electrode forming material of the present invention described above (i.e., the electrode forming material of the present invention). Such a non-aqueous secondary battery electrode composition of the present invention includes a non-aqueous secondary battery negative electrode composition (hereinafter simply referred to as "the negative electrode composition of the present invention") and a non-aqueous secondary battery positive electrode composition (hereinafter simply referred to as "the positive electrode composition of the present invention"). The negative electrode composition of the present invention contains a negative electrode active material as an active material and the electrode forming material of the present invention as an electrode binder composition. The negative electrode active material is not particularly limited, and examples include carbon-based negative electrode active materials, metal-based negative electrode active materials, and negative electrode active materials that combine these. Carbon-based anode active materials refer to active materials with a carbon-based skeleton that can be doped with lithium. Examples of carbon-based anode active materials include graphite materials and carbonaceous materials. Examples of graphite materials include natural graphite and artificial graphite. Examples of carbonaceous materials include easily graphitizable carbon such as coke, mesocarbon microbeads (MCMB), mesophase pitch carbon fibers, and pyrolysis vapor-grown carbon fibers, and examples of difficult-to-graphitize carbon such as phenolic resin calcined bodies, polyacrylonitrile carbon fibers, pseudoisotropic carbon, furfuryl alcohol resin calcined bodies (PFA), and hard carbon. Furthermore, as metallic anode active materials, for example, lithium metal, elemental metals that can form lithium alloys (e.g., Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, Zn, Ti, etc.) and their alloys, as well as their oxides, sulfides, nitrides, silides, carbides, phosphides, etc., can be used. Among these, silicon-containing active materials (silicon-based anode active materials) are preferred as metallic anode active materials. By using silicon-based anode active materials, the capacity of lithium-ion secondary batteries can be increased. Examples of silicon-based anode active materials include silicon (Si), silicon-containing alloys, SiO, SiO ｘExamples include composites of Si-containing materials and conductive carbon obtained by coating or compounding Si-containing materials with conductive carbon.

[0046] Further, the composition for a negative electrode of the present invention may further contain a conductive material. Examples of the conductive material include conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, and polyacene, and porous carbon. These may be used alone or in combination of two or more.

[0047] The composition for a negative electrode of the present invention is obtained by mixing and dispersing the above-described negative electrode active material and the electrode-forming material of the present invention as a non-aqueous secondary battery electrode binder composition. There is no particular limitation on the addition order during mixing. Further, from the viewpoint of adjusting the viscosity of the obtained composition for a negative electrode of the present invention and enhancing the dispersion stability, an aqueous medium may be appropriately added. For dispersion, a dispersion device such as a stirrer, a rotation-revolution mixer, a ball mill, a super sand mill, or a pressure kneader can be used.

[0048] Further, the composition for a positive electrode of the present invention contains a positive electrode active material as an active material and the electrode-forming material of the present invention as an electrode binder composition. The positive electrode active material is not particularly limited. For example, when manufacturing a lithium-ion secondary battery among non-aqueous electrolyte secondary batteries, examples include metal compounds, metal oxides, metal sulfides, and conductive polymers capable of doping or intercalating lithium ions. Specifically, lithium-cobalt composite oxides (LCO) such as lithium cobalt oxide (LiCoO ２ ), lithium nickel oxide (LiNiO ２ ), lithium manganate (LiMnO ２ ), and composite oxides thereof (LiCo ｘ Ni ｙ Mn ｚ O ２ , x + y + z = 1; lithium nickel manganese cobalt composite oxide (NMC)); lithium manganese spinel (LiMn ２ O ４ ), lithium vanadium compounds, V ２ O ５ , V ６ O １３ , VO２ MnO ２ , TiO ２ MoV ２ O ８ TiS ２ , V ２ S ５ , VS ２ MoS ２ MoS ３ , Cr ３ O ８ , Cr ２ O ５ Olivine type LiMPO ４ (wherein M is Co, Ni, Mn, or Fe); Examples include conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, and polyacene, and porous carbon. These may be used individually or in combination of two or more. Among these, olivine-type LiFePO is preferred from the viewpoint of operating voltage, volume density, theoretical capacity, high-temperature stability, and economics. ４ It is more preferable to use lithium iron phosphate compounds (LFPs) such as the above.

[0049] The average particle size of the positive electrode active material is not particularly limited, but for example, when lithium-cobalt composite oxide (LCO) or lithium-nickel-manganese-cobalt composite oxide (NMC) is used as the positive electrode active material, the average particle size is usually preferably 1 μm to 100 μm, and more preferably 5 μm to 50 μm. Also, when lithium iron phosphate compound (LFP) is used as the positive electrode active material, the average particle size is usually preferably 0.01 μm to 5 μm, and more preferably 0.1 μm to 1 μm. When the average particle size of the positive electrode active material is within the above range, the positive electrode expansion rate during charging and discharging is small when used as a secondary battery, and it is easier to prevent a decrease in the reversible charge-discharge capacity per unit volume. Furthermore, it is easier to suppress peeling of the electrode film (positive electrode material layer) from the current collector during electrode film fabrication. The average particle size of the positive electrode active material is the particle size (D50) at which the cumulative volume reaches 50% when the volume cumulative distribution curve is drawn from the smallest diameter side, based on the particle size distribution measured by dynamic light scattering using a laser diffraction particle size analyzer or the like.

[0050] The positive electrode active material may have at least a portion of its surface covered with a coating material. The coating material is preferably a substance that exhibits electronic conductivity, lithium-ion conductivity, and an effect of suppressing electrolyte decomposition, such as electronically conductive materials like carbon, titanium, and nickel. Among these, carbon is preferred, and low-crystallinity carbon is more preferred, from the viewpoint of improving the chemical and thermal stability of the positive electrode active material and suppressing a decrease in the charge-discharge performance of the resulting secondary battery. When at least a portion of the surface of the positive electrode active material is covered with a coating material, the average thickness of the coating layer is preferably 10 nm to 300 nm, and more preferably 20 nm to 200 nm. Furthermore, the content of the coating material is preferably 1 to 30% by mass relative to the total amount of the components of the positive electrode active material and the coating material.

[0051] Furthermore, the positive electrode composition of the present invention may further contain a conductive material. Examples of conductive materials include conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, and polyacene, as well as porous carbon. These may be used individually or in combination of two or more types.

[0052] The positive electrode composition of the present invention is obtained by mixing and dispersing the positive electrode active material described above, a conductive material, and the electrode-forming material of the present invention as a binder composition for the positive electrode of a non-aqueous secondary battery. There are no particular restrictions on the order of addition during mixing. Furthermore, a non-aqueous solvent may be added as appropriate from the viewpoint of adjusting the viscosity of the resulting positive electrode composition of the present invention and improving dispersion stability. Dispersion can be carried out using dispersion equipment such as a stirrer, a rotary-orbit mixer, a ball mill, a super sand mill, or a pressurized kneader.

[0053] 4. Non-aqueous secondary battery The present invention also relates to a non-aqueous secondary battery electrode A (hereinafter also referred to as "electrode A of the present invention") comprising an electrode material layer (negative electrode material layer or positive electrode material layer) formed using the electrode composition of the present invention described above. Such a non-aqueous secondary battery electrode of the present invention includes a non-aqueous secondary battery negative electrode (hereinafter also simply referred to as "negative electrode A of the present invention") and a non-aqueous secondary battery positive electrode (hereinafter also simply referred to as "positive electrode A of the present invention"). The present invention also relates to a non-aqueous secondary battery (hereinafter also referred to as "non-aqueous secondary battery A of the present invention") comprising a negative electrode, a positive electrode, an electrolyte, and a separator, wherein at least one of the positive electrode and the negative electrode is the non-aqueous secondary battery electrode A of the present invention described above. The electrode forming material of the present invention, as a binder composition for non-aqueous secondary battery electrodes, has excellent durability against the electrolyte (electrolyte resistance) and film-forming properties. Therefore, the electrode material layer formed from the electrode composition containing the non-aqueous secondary battery electrode forming material of the present invention exhibits excellent charge-discharge capacity and capacity retention rate. That is, the non-aqueous secondary battery A of the present invention having an electrode A equipped with such an electrode material layer exhibits good charge-discharge characteristics and excellent capacity retention rate. As the non-aqueous secondary battery A of the present invention, non-aqueous electrolyte secondary batteries and solid-state electrolyte secondary batteries are preferred, and in particular, non-aqueous electrolyte secondary batteries equipped with an electrode material layer formed using the non-aqueous secondary battery electrode composition of the present invention tend to exhibit excellent performance. For example, if the secondary battery A of the present invention is a wet-type electrolyte secondary battery, it can be constructed by arranging a negative electrode A and a positive electrode A, at least one of which is the non-aqueous secondary battery electrode A of the present invention described above, opposite each other via a separator, and injecting an electrolyte.

[0054] <Negative Electrode> The negative electrode A of the present invention can be obtained, for example, by applying the above-described non-aqueous secondary battery electrode composition of the present invention to a current collector to form a negative electrode material layer as a thin film. Alternatively, the negative electrode composition of the present invention may be molded into a sheet, pellet, or other shape and integrated with the current collector to obtain the negative electrode.

[0055] Examples of materials for the current collector include copper, nickel, titanium, and stainless steel. The shape of the current collector is preferably a strip shape such as foil, perforated foil, or mesh. Porous materials such as porous metal (foamed metal) and carbon paper can also be used as current collectors. Examples of methods for applying the negative electrode composition to the current collector include metal mask printing, electrostatic coating, dip coating, spray coating, roll coating, doctor blade coating, gravure coating, and screen printing. After application, it is preferable to perform rolling treatment using a flat plate press or calender roll as needed. Alternatively, the negative electrode material layer may be obtained by forming the paste-like negative electrode composition into a sheet or pellet and then integrating it with the current collector using a roll, press, or a combination thereof.

[0056] The negative electrode material layer formed on the current collector or the negative electrode material layer integrated with the current collector is preferably heat-treated. This heat treatment removes the aqueous medium (B) derived from the electrode-forming material of the present invention as a binder composition for non-aqueous secondary battery electrodes, promotes the fusion of core-shell type particles (A), and improves the adhesion between negative electrode active materials and between the negative electrode active materials and the current collector. The heat treatment temperature is preferably in the range of 50 to 220°C, and more preferably in the range of 100 to 200°C. There are no particular restrictions on the heat treatment time, but it is usually in the range of 1 minute to 20 hours. It is preferable to perform the heat treatment in a non-oxidizing gas atmosphere such as helium, argon, or nitrogen, or in a vacuum atmosphere, from the viewpoint of preventing oxidation of the current collector during heat treatment. Furthermore, after heat treatment, the negative electrode, which consists of the negative electrode material layer formed on the current collector or the negative electrode material layer integrated with the current collector, is preferably pressurized from the viewpoint of adjusting the electrode density. The electrode density of the negative electrode is usually 1 to 1.8 g / cm³. ３ Preferably, it is 1.1 to 1.7 g / cm³. ３ It is more preferable that the concentration be 1.2 to 1.6 g / cm³. ３ It is even more preferable that the electrode density is as follows: While higher electrode density tends to improve adhesion and electrode volumetric density, if it is too high, the voids in the electrode decrease, making it difficult to suppress the negative electrode expansion rate and potentially reducing the capacity retention rate. Therefore, an optimal range for electrode density is selected.

[0057] <Positive Electrode> Positive electrode A is obtained by forming a positive electrode material layer on the surface of a current collector in the same manner as negative electrode A. For example, a positive electrode material slurry is prepared by kneading the positive electrode active material and the non-aqueous secondary battery electrode composition of the present invention described above together with a solvent using a dispersion device such as a stirrer, ball mill, super sand mill, or pressurized kneader. This positive electrode material slurry can be applied to a current collector (e.g., copper foil) to form a positive electrode material layer. Alternatively, the positive electrode composition of the present invention may be molded into a sheet, pellet, or other shape and integrated with a current collector to obtain a positive electrode. Furthermore, instead of the non-aqueous secondary battery electrode composition of the present invention, an organic binder other than the non-aqueous secondary battery electrode composition can be used as the positive electrode. Examples of such organic binders include styrene-butadiene rubber copolymers (hereinafter also referred to as "SBR"); ethylenically unsaturated carboxylic acid copolymers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, (meth)acrylonitrile, and hydroxyethyl (meth)acrylate, and unsaturated carboxylic acid copolymers such as (meth)acrylic copolymers made from ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid; and polymer compounds such as polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polyimide, polyamideimide, and carboxymethylcellulose (hereinafter also referred to as "CMC"). Depending on their physical properties, these organic binders may be dispersed or dissolved in water, or dissolved in an organic solvent such as N-methyl-2-pyrrolidone.

[0058] The content of organic binder in the positive electrode material layer of the lithium-ion secondary battery positive electrode is preferably 1 to 30% by mass, more preferably 2 to 20% by mass, and even more preferably 3 to 15% by mass. When the content of organic binder is 1% by mass or more, adhesion is improved, and the destruction of the positive electrode structure due to expansion or contraction during charging and discharging is more easily suppressed. On the other hand, when it is 30% by mass or less, the increase in electrode resistance is more easily suppressed.

[0059] The positive electrode slurry may further contain conductive additives as needed. Examples of conductive additives include carbon black, graphite, acetylene black, conductive oxides, and nitrides. If the positive electrode slurry further contains conductive additives, the amount is preferably in the range of 1 to 15% by mass relative to the positive electrode active material.

[0060] Examples of materials for the current collector include copper, nickel, titanium, and stainless steel. The shape of the current collector is preferably a strip shape such as foil, perforated foil, or mesh. Porous materials such as porous metal (foamed metal) and carbon paper can also be used as current collectors. Examples of methods for applying the positive electrode material slurry to the current collector include metal mask printing, electrostatic painting, dip coating, spray coating, roll coating, doctor blade coating, gravure coating, and screen printing. After application, it is preferable to perform rolling treatment using a flat plate press or calender roll as needed. Alternatively, the positive electrode material layer may be obtained by forming the paste-like positive electrode material slurry into a sheet or pellet and then integrating it with the current collector using a roll, press, or a combination thereof.

[0061] The positive electrode material layer formed on the current collector or the positive electrode material layer integrated with the current collector is preferably heat-treated according to the type of organic binder. This heat treatment removes the aqueous medium (B) derived from the electrode-forming material of the present invention as a binder composition for non-aqueous secondary battery electrodes, promotes the fusion of core-shell type particles (A), and improves the adhesion between positive electrode active materials and between positive electrode active materials and the current collector. The heat treatment temperature is preferably in the range of 50 to 220°C, and more preferably in the range of 100 to 200°C. There are no particular restrictions on the heat treatment time, which is usually in the range of 1 minute to 20 hours. When an organic binder with polyimide or polyamide-imide as the main skeleton is used instead of the non-aqueous secondary battery electrode composition of the present invention, it is preferable to heat-treat at 150 to 450°C. It is preferable to perform the heat treatment in a non-oxidizing gas atmosphere such as helium, argon, or nitrogen, or in a vacuum atmosphere, from the viewpoint of preventing oxidation of the current collector during heat treatment.

[0062] Furthermore, after heat treatment, the positive electrode, which consists of a positive electrode material layer formed on the current collector or a positive electrode material layer integrated with the current collector, is preferably subjected to pressure treatment from the viewpoint of adjusting the electrode density. The electrode density of the positive electrode is usually 1 to 1.8 g / cm³. ３ Preferably, it is 1.1 to 1.7 g / cm³. ３ It is more preferable that the concentration be 1.2 to 1.6 g / cm³. ３ It is even more preferable that the electrode density is as follows: While higher electrode density tends to improve adhesion and electrode volumetric density, if it is too high, the voids in the electrode decrease, making it difficult to suppress the positive electrode expansion rate and potentially reducing the capacity retention rate. Therefore, an optimal range for electrode density is selected.

[0063] <Separator> As a separator, nonwoven fabrics, cloths, microporous films, or combinations thereof, mainly composed of polyolefins such as polyethylene and polypropylene can be used. However, if the structure of the non-aqueous electrolyte secondary battery being manufactured is such that the positive and negative electrodes do not come into direct contact, a separator is not required.

[0064] <Electrolyte> For example, LiClO ４ LiPF ６ LiAsF ６ LiBF ４ LiSO ３ CF ３ A so-called organic electrolyte can be used, which is obtained by dissolving lithium salts such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, cyclopentanone, sulfolane, 3-methylsulfolane, 2,4-dimethylsulfolane, 3-methyl-1,3-oxazolidine-2-one, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butyl ethyl carbonate, dipropyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, methyl acetate, ethyl acetate, etc., in one or more non-aqueous solvents.

[0065] The structure of a secondary battery using the electrode-forming material of the present invention as a binder composition for non-aqueous secondary battery electrodes is not particularly limited, but it is common to have a structure in which a positive electrode, a negative electrode, and a separator, if necessary, are wound in a flat spiral shape to form a wound electrode plate group, or these are stacked as flat plates to form a stacked electrode plate group, and these electrode plate groups are sealed in an outer casing. Secondary batteries using the electrode-forming material of the present invention as a binder composition for non-aqueous secondary battery electrodes are used, for example, as paper type batteries, button type batteries, coin type batteries, stacked type batteries, cylindrical type batteries, prismatic type batteries, etc. The electrode-forming material of the present invention as a binder composition for non-aqueous secondary battery electrodes is also applicable to electrochemical devices in general that use the insertion and removal of lithium ions as a charge and discharge mechanism, such as hybrid capacitors and solid lithium secondary batteries.

[0066] 5. Composition for Coating Conductive Substrates The electrode-forming material of the present invention can be suitably used as a binder for forming a coating layer containing a conductive material on the surface of a conductive substrate as a current collector. That is, the present invention also includes a composition for coating a conductive substrate (hereinafter also referred to as "the composition for coating a conductive substrate of the present invention") containing a conductive material and the electrode-forming material of the present invention. As described above, the electrode-forming material of the present invention contains core-shell type particles (A) and has excellent bonding properties with all kinds of active materials and conductive metals as current collectors. Therefore, it is presumed that the adhesion strength between a current collector having a coating layer formed from the composition for coating a conductive substrate of the present invention and the electrode material layer can be increased. A secondary battery having an electrode formed from a current collector having such a coating layer can improve battery characteristics such as charge / discharge efficiency and capacity retention rate, as well as durability against electrolyte (electrolyte resistance). It can also be inexpensive and reduce environmental impact.

[0067] The conductive material contained in the conductive substrate coating composition of the present invention is not particularly limited and includes the same conductive materials as those contained in the negative electrode composition of the present invention described above. Among these, conductive fibrous carbon such as vapor-grown carbon fibers (VGCF), single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), and carbon nanofibers (CNF); conductive graphite particles such as natural graphite and artificial graphite; conductive carbon black such as acetylene black, Ketjen black, and furnace black; and carbon materials such as conductive polymers such as polyacetylene, polyaniline, polypyrrole, polythiophene, and polyacene are preferred. These may be used individually or in combination of two or more types.

[0068] The size of the conductive material is not particularly limited. When the conductive material is particulate, such as spherical or plate-shaped, its primary particle diameter is usually preferably in the range of 0.001 to 2 μm, more preferably in the range of 0.002 to 0.3 μm, and even more preferably in the range of 0.01 to 0.1 μm. Here, the primary particle diameter of the conductive material is the value obtained by measuring the specific surface area using the nitrogen adsorption method (BET method) and calculating the average particle size assuming the particles are spherical. When the conductive material is fibrous, such as fibrous or needle-shaped, its fiber diameter is usually preferably in the range of 1 nm to 300 nm, more preferably in the range of 5 nm to 150 nm, and even more preferably in the range of 10 nm to 50 nm. When the conductive material is fibrous, its fiber length is usually preferably in the range of 1 μm to 100 μm, more preferably in the range of 3 μm to 80 μm, and even more preferably in the range of 5 μm to 50 μm. When the conductive material is fibrous, the fiber diameter and fiber length are calculated by measuring the diameter and fiber length of any number of fibers from scanning cell microscope images and averaging them. If the size of the conductive material is within the above range, the adhesion strength between the coating layer formed from the conductive substrate coating composition of the present invention and the electrode material layer tends to improve.

[0069] The conductive substrate coating composition of the present invention preferably contains a dispersion medium. The dispersion medium is preferably the same type as the aqueous medium (B) contained in the electrode-forming material of the present invention. In the conductive substrate coating composition of the present invention, the content of the conductive material is preferably in the range of 1 to 30% by mass, more preferably in the range of 5 to 30% by mass, and particularly preferably in the range of 5 to 15% by mass, relative to the solid content of the electrode-forming material of the present invention. When the content of the conductive material is within the above range, the coating layer formed from the conductive substrate coating composition of the present invention exhibits excellent conductivity, and the bonding between the conductive substrate and the electrode material layer is easily improved.

[0070] The conductive substrate coating composition of the present invention is obtained by mixing and dispersing the conductive material described above and the electrode-forming material of the present invention. There are no particular restrictions on the order of addition during mixing. Furthermore, from the viewpoint of adjusting the viscosity of the obtained conductive substrate coating composition of the present invention and improving dispersion stability, the above-mentioned dispersion medium may be added as appropriate. Dispersion can be carried out using dispersion equipment such as a stirrer, a rotary-orbit mixer, a ball mill, a super sand mill, or a pressurized kneader.

[0071] 《Current Collector》 The present invention also includes a current collector (hereinafter also referred to as "the current collector of the present invention") having a coating layer formed of the conductive layer substrate coating composition of the present invention on one or both sides of a sheet-like conductive substrate. The current collector of the present invention includes a negative electrode current collector (hereinafter also referred to as "the negative electrode current collector of the present invention") and a positive electrode current collector (hereinafter also referred to as "the positive electrode current collector of the present invention").

[0072] The material of the conductive substrate constituting the negative electrode current collector of the present invention is not particularly limited, and examples include metallic materials such as copper, iron, aluminum, nickel, stainless steel, and nickel-plated steel, and carbon materials such as carbon cloth and carbon paper. The form of the negative electrode current collector of the present invention is not particularly limited, but examples of metallic materials include metal foil, metal cylinder, metal coil, and metal plate, and examples of carbon materials include carbon plate, carbon thin film, and carbon cylinder. Among these, metal foil is preferred, and copper foil is more preferred.

[0073] The material of the conductive substrate constituting the positive electrode current collector of the present invention is not particularly limited, and examples include metallic materials such as copper, iron, aluminum, nickel, stainless steel, and nickel-plated steel, and carbon materials such as carbon cloth and carbon paper. The form of the positive electrode current collector of the present invention is not particularly limited, but examples of metallic materials include metal foil, metal cylinder, metal coil, and metal plate, and examples of carbon materials include carbon plate, carbon thin film, and carbon cylinder. Among these, metal foil is preferred, and aluminum foil is more preferred.

[0074] The method for forming a coating layer on one or both sides of a sheet-like conductive substrate using the conductive substrate coating composition of the present invention is not particularly limited. That is, for example, the current collector of the present invention can be formed by applying the above-described conductive substrate coating composition of the present invention to one or both sides of a sheet-like conductive substrate and drying it to form a coating layer on the surface of the conductive substrate. Examples of application methods include metal mask printing, electrostatic coating, dip coating, spray coating, roll coating, doctor blade coating, gravure coating, and screen printing. After application, it is preferable to perform rolling treatment using a flat plate press, calender roll, etc., as needed.

[0075] The coating layer formed on the surface of the conductive substrate is preferably heat-treated. This heat treatment removes the aqueous medium (B) derived from the dispersion medium and / or the electrode-forming material of the present invention, promotes the fusion of core-shell type particles (A) and improves the adhesion between the conductive substrate and the electrode material layer. The heat treatment temperature is preferably in the range of 50 to 220°C, and more preferably in the range of 100 to 200°C. There are no particular restrictions on the heat treatment time, which is usually in the range of 1 minute to 20 hours. The heat treatment is preferably carried out in an inert gas atmosphere such as helium, argon, or nitrogen, or in a vacuum atmosphere. The thickness of the coating layer is preferably 0.5 to 5 μm, more preferably 0.7 to 3 μm, and particularly preferably 1 to 2 μm, from the viewpoint of easily increasing the adhesion strength between the current collector and the electrode material layer of the present invention.

[0076] Electrodes The present invention also relates to an electrode (hereinafter also referred to as "electrode B of the present invention") comprising the current collector of the present invention described above (i.e., the negative electrode current collector of the present invention, or the positive electrode current collector of the present invention). Electrode B of the present invention includes a negative electrode (hereinafter also referred to as "negative electrode B of the present invention") or a positive electrode (hereinafter also referred to as "positive electrode B of the present invention"). Electrode B of the present invention can be suitably used, for example, as an electrode in the non-aqueous secondary battery of the present invention described later.

[0077] The negative electrode B of the present invention comprises a negative electrode current collector and a negative electrode material layer. The negative electrode material layer may be formed using the negative electrode composition of the present invention described above, or it may be formed using a negative electrode composition outside the scope of the present invention. Preferably, the negative electrode B of the present invention is obtained by coating the negative electrode composition of the present invention described above onto the negative electrode current collector to form the negative electrode material layer. The details of forming the negative electrode material layer are the same as those for forming the negative electrode material layer in the negative electrode A of the present invention described above.

[0078] The negative electrode material layer formed on the negative electrode current collector of the present invention, or the negative electrode material layer integrated with the negative electrode current collector of the present invention, is preferably heat-treated. Such heat treatment removes the aqueous medium (B) derived from the electrode-forming material of the present invention, promotes the fusion of core-shell type particles (A), and improves the bonding between negative electrode active materials and between negative electrode active materials and the negative electrode current collector. The details of the conditions such as the preferred temperature for heat treatment are the same as those for the heat treatment used when forming the negative electrode material layer in negative electrode A of the present invention described above. Furthermore, from the viewpoint of adjusting the electrode density, it is preferable to pressurize the negative electrode after heat-treating the negative electrode material layer. The details such as the preferred range of electrode density are also the same as those described above for negative electrode A of the present invention.

[0079] Positive electrode B of the present invention comprises a positive electrode current collector and a positive electrode material layer. The positive electrode material layer may be formed using the positive electrode composition of the present invention described above, or it may be formed using a positive electrode composition outside the scope of the present invention. Preferably, positive electrode B of the present invention is obtained by coating the positive electrode composition of the present invention described above onto the positive electrode current collector to form a positive electrode material layer. The details of forming the positive electrode material layer are the same as those for forming the positive electrode material layer in positive electrode A of the present invention described above.

[0080] The positive electrode material layer formed on the positive electrode current collector of the present invention, or the positive electrode material layer integrated with the positive electrode current collector of the present invention, is preferably heat-treated. Such heat treatment removes the aqueous medium (B) derived from the electrode-forming material of the present invention, promotes the fusion of core-shell type particles (A), and improves the bonding between positive electrode active materials and between positive electrode active materials and positive electrode current collectors. The details of the conditions for suitable temperature and other conditions for heat treatment are the same as those for the heat treatment used when forming the positive electrode material layer in positive electrode A of the present invention described above. Furthermore, from the viewpoint of adjusting the electrode density, it is preferable to pressurize the positive electrode after heat-treating the positive electrode material layer. The details of the suitable range of electrode density and other conditions are the same as those described above for positive electrode A of the present invention. Either the positive electrode material layer or the negative electrode material layer may be a negative electrode material layer or / or a positive electrode material layer formed using the electrode composition of the present invention described above (i.e., the negative electrode composition and / or positive electrode composition of the present invention). Furthermore, either the positive electrode layer or the negative electrode layer may be formed from an electrode composition outside the scope of the present invention, obtained using a binder composition containing a binder other than core-shell type particles (A).

[0081] 《Non-aqueous secondary battery》 The present invention also relates to a non-aqueous secondary battery (hereinafter also referred to as "non-aqueous secondary battery B of the present invention") that comprises one or more electrodes selected from the group consisting of the electrode B of the present invention, i.e., the negative electrode B of the present invention and the positive electrode B of the present invention. The electrode forming material of the present invention has excellent durability to electrolyte (electrolyte resistance) and film-forming properties, and a current collector having a coating layer formed from the conductive substrate coating composition of the present invention containing the electrode forming material exhibits high bonding properties with the electrode material layer. Therefore, the non-aqueous secondary battery B of the present invention, which comprises the electrode B of the present invention equipped with such a current collector, exhibits good charge-discharge characteristics and excellent battery characteristics such as capacity retention rate.

[0082] The non-aqueous secondary battery B of the present invention is preferably a non-aqueous electrolyte secondary battery or a solid-state electrolyte secondary battery, and in particular, a non-aqueous electrolyte secondary battery equipped with the electrode B of the present invention tends to exhibit excellent performance. When the secondary battery of the present invention is a non-aqueous electrolyte secondary battery, it comprises a negative electrode, a positive electrode, a separator, and an electrolyte, and at least one of the negative electrode and the positive electrode can be configured using the negative electrode B or positive electrode B of the present invention as described above.

[0083] As the positive electrode, positive electrode B of the present invention may be used. Alternatively, a positive electrode outside the scope of the present invention may be used, formed from a positive electrode composition containing an electrode binder composition other than the electrode forming material of the present invention, which contains a binder different from that of the core-shell type particles (A). As the negative electrode, negative electrode B of the present invention may be used. Alternatively, a negative electrode outside the scope of the present invention may be used, formed from a negative electrode composition containing an electrode binder composition other than the electrode forming material of the present invention, which contains the aforementioned binder different from that of the core-shell type particles (A). Other binders include, for example, styrene-butadiene rubber copolymers; unsaturated carboxylic acid copolymers such as (meth)acrylic copolymers made of ethylenically unsaturated carboxylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, (meth)acrylonitrile, and hydroxyethyl (meth)acrylate, and ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic acid; and polymer compounds such as polyvinylidene fluoride, polyethylene oxide, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polyimide, polyamideimide, and carboxymethylcellulose. These binders may be dispersed or dissolved in water, or dissolved in organic solvents such as N-methyl-2-pyrrolidone.

[0084] Details of the separator and electrolyte, as well as structural examples, in the non-aqueous secondary battery B of the present invention are the same as those described above in the description of the non-aqueous secondary battery A of the present invention. The non-aqueous secondary battery B of the present invention can be used, for example, as a paper battery, button battery, coin battery, stacked battery, cylindrical battery, prismatic battery, etc.

[0085] The non-aqueous secondary battery electrode forming material, non-aqueous secondary battery electrode binder composition, method for manufacturing the non-aqueous secondary battery electrode forming material, electrode composition, conductive substrate coating composition, current collector, electrode, and secondary battery having the electrode of the present invention have been described above. However, the present invention is not limited to the configurations of the embodiments described above. For example, the non-aqueous secondary battery electrode forming material, non-aqueous secondary battery electrode binder composition, method for manufacturing the non-aqueous secondary battery electrode forming material, electrode composition, conductive substrate coating composition, current collector, electrode, and secondary battery having the electrode of the present invention may each have additional configurations in addition to the configurations of the embodiments described above, or may be replaced with any configuration that performs a similar function.

[0086] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below. The raw materials used in each example and comparative example are listed below.

[0087] <Vinyl monomers with acidic groups> AA: Acrylic acid MAA: Methacrylic acid IA: Itaconic acid <(Meth)acrylic acid ester monomers> MMA: Methyl methacrylate BA: Butyl acrylate 2EHA: 2-ethylhexyl acrylate GMA: Glycidyl methacrylate HEMA: 2-hydroxyethyl methacrylate <Vinyl monomers with crosslinking reactive groups> DVB: Divinylbenzene EGDAC: Ethylene glycol diacrylate MPTMS: 3-(trimethoxysilyl)propyl methacrylate <Aromatic vinyl monomers> ST: Styrene <Vinyl monomers with amide groups> AM: Acrylamide DM: Dimethylacrylamide <Vinyl monomers with crosslinking reactive groups and amide groups> NMAM: N-methylolacrylamide MAC: N-methylolmethacrylamide NBAM: N-n-butoxymethylacrylamide <Vinyl monomers with cyano groups> AN: Acrylonitrile <Fluorine-containing monomer> TF3F: 2,2,2-trifluoroethyl acrylate <Emulsifier> SR-10: Ether sulfate type ammonium salt (Reactive surfactant Adekarya Soap SR-10 manufactured by ADEKA Corporation) 08E: Polyoxyethylene oleyl cetyl ether sulfate ammonium (Non-reactive surfactant Hytenol 08E manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)

[0088] Example 1 (1) Preparation of Binder Composition for Negative Electrode <Shell Formation Process> 220 parts by mass of deionized water and 0.5 parts by mass of SR-10 were charged into a reaction vessel equipped with a stirrer, thermometer, and cooler, and heated to 80°C. Next, an emulsion was prepared by mixing 50 parts by mass of deionized water, 0.5 parts by mass of SR-10, 6 parts by mass of ST2, 68 parts by mass of 2EHA, and 6 parts by mass of AA. This emulsion and an aqueous solution prepared by dissolving 0.2 parts by mass of ammonium persulfate in 10 parts by mass of deionized water were simultaneously added dropwise to the reaction vessel over 3 hours to carry out polymerization. After the dropwise addition was completed, the temperature was maintained at 80°C for 2 hours. After that, it was cooled to room temperature, and the non-volatile content was adjusted to 26.0% with deionized water to obtain an emulsion in which polymer particles were dispersed in an aqueous medium (deionized water). <Core Formation Process> The reaction vessel was heated again to 80°C, and a mixture of 75 parts by mass of ST, 20 parts by mass of 2EHA, 4 parts by mass of HEMA, and 1 part by mass of DVB was simultaneously added dropwise to the reaction vessel over 3 hours to carry out polymerization. After the dropwise addition was complete, the temperature was maintained at 80°C for 2 hours. The mixture was cooled to room temperature, the pH was adjusted to 7 with 25% aqueous ammonia, 1 part by mass of activide MBS and 40.1 parts by mass of activide MV were added, and the non-volatile content was adjusted to 40.0% with deionized water to obtain the negative electrode binder composition.

[0089] (2) Preparation of the negative electrode composition 48.75 parts by mass of artificial graphite and 48.75 parts by mass of natural graphite were weighed out as negative electrode active materials and stirred in a rotary-orbit mixer for 30 seconds. Next, 48.0 parts by mass (0.96 parts by mass in terms of solid content) of an aqueous solution (hereinafter referred to as "CMC solution") prepared by dissolving carboxymethylcellulose sodium salt (Sunrose MAC350HC manufactured by Nippon Paper Industries Co., Ltd.) in distilled water and adjusting the non-volatile content to 2% was added and mixed until the whole thing became a paste, and then stirred in a rotary-orbit mixer for 2 minutes. Since heat was generated by stirring, it was cooled to room temperature with ice water, stirred again in a rotary-orbit mixer for 2 minutes, and then cooled to room temperature with ice water. Subsequently, 27.0 parts by mass (0.54 parts by mass in terms of solid content) of the above CMC solution was added to this mixture and mixed until the whole thing became uniform, then stirred in a rotary-orbit mixer for 2 minutes, and then cooled to room temperature with ice water. Ten parts by weight of distilled water and 3.75 parts by mass (1.5 parts by mass in terms of solid content) of the negative electrode binder composition obtained in (1) above were added, and the mixture was stirred again in a rotary-orbit mixer for 2 minutes, and then cooled to room temperature with ice water. The viscosity of the obtained slurry was measured with a B-type viscometer at 25°C and 30 rpm, and distilled water was added until the viscosity was in the range of 2000 to 4000 mPa·s. Finally, the mixture was stirred in a rotary-orbit mixer for 30 seconds to prepare a slurry-like negative electrode composition.

[0090] (3) The coating amount (surface density) of the negative electrode composition after drying of the negative electrode is 8.8 mg / cm². ２ The gap of the bar coater was adjusted to achieve the desired result, and the negative electrode composition was coated onto the copper foil current collector using this bar coater. The mixture was then dried for 8 minutes in a forced-air dryer set to 80°C. The dried electrodes were cut to a width of 40 mm and pressed using a roll press machine (Small Desktop Roll Press SA-602, manufactured by Tester Industries Co., Ltd.) to achieve a layer density of 1.55 g / cm³. ３ After pressing in this manner, the material was vacuum-dried at 110°C for 10 hours to obtain the negative electrode.

[0091] (4) Preparation of the positive electrode composition As the positive electrode active material, olivine-type lithium iron phosphate (LiFePO) ４94.0 parts by mass of ) and 3.0 parts by mass of acetylene black as a conductive material were weighed out and stirred for 30 seconds in a rotating-orbit mixer (Thinky "ARE-310 (product name)") at a rotation speed of 1000 rpm and an orbital speed of 2000 rpm. Thereafter, stirring using the rotating-orbital mixer was performed using the same apparatus and conditions unless otherwise specified. Next, 2.16 parts by mass of polyvinylidene fluoride (PVDF) and 19.0 parts by mass of NMP were added and mixed until the mixture became a paste, then stirred in the rotating-orbital mixer for 2 minutes. Since the mixture generated heat during stirring, it was cooled to room temperature in ice water, stirred again in the rotating-orbital mixer for 2 minutes, and then cooled to room temperature in ice water. Subsequently, 0.84 parts by mass of polyvinylidene fluoride (PVDF) and 5 parts by mass of NMP were added to this mixture and mixed until the mixture was homogenized. The viscosity of the obtained slurry was measured using a B-type viscometer at 25°C and 30 rpm, and NMP was added to bring it within the range of 2000 to 4000 mPa·s. Finally, the mixture was stirred for 30 seconds in a rotational mixer to prepare a slurry-like cathode composition.

[0092] (5) The coating amount (surface density) of the cathode composition after the preparation and drying of the cathode is 25.0 mg / cm². ２ The gap of the bar coater was adjusted to achieve the desired result, and the positive electrode composition obtained above was coated onto the carbon-coated aluminum foil, which served as the current collector, using this bar coater. The mixture was then dried for 10 minutes in a forced-air dryer set to 80°C. The dried electrodes were cut to a width of 40 mm and pressed using a roll press machine (Small Desktop Roll Press SA-602, manufactured by Tester Industries Co., Ltd.) to achieve a layer density of 2.5 g / cm³. ３ After pressing in this manner, the cathode was obtained by vacuum drying at 110°C for 10 hours.

[0093] (6) Fabrication of a secondary battery The negative electrode fabricated above was cut into a 24 mm x 24 mm square with a tab, and the positive electrode fabricated above was cut into a 22 mm x 22 mm square with a tab, using a die-cutting blade. Nickel tab leads were welded to the tab portion of the cut electrodes, and aluminum tab leads were welded to the tab portion of the negative electrode, and aluminum tab leads were welded to the tab portion of the positive electrode. On the other hand, a 25 μm thick polyethylene microporous membrane was cut into a 28 mm x 3.8 cm rectangle using a die-cutting blade as a separator. The positive and negative electrodes were placed facing each other with this separator in between, wrapped in laminate film, and the tab portion was fixed by heat sealing. Then, LiPF ６ The non-aqueous electrolyte solution obtained by dissolving the compound in a 30 / 30 / 40 mixed solution of ethylene carbonate / dimethyl carbonate / methyl ethyl carbonate (volume ratio) at a concentration of 1 mol / L, and then adding 1 vol% vinyl carbonate and 5 vol% fluoroethylene carbonate, was prepared by adding 300 μL of this solution and completely sealing it by vacuum lamination to produce the laminate-type secondary battery of Example 1.

[0094] Comparative Example 1 A negative electrode composition, a negative electrode, a positive electrode composition, a positive electrode, and a secondary battery were obtained in the same manner as in Example 1, except that a negative electrode binder composition prepared by the method described below was used as the negative electrode binder composition. (1) Preparation of the negative electrode binder composition 220 parts by mass of deionized water and 0.5 parts by mass of SR-10 were charged into a reaction vessel equipped with a stirrer, thermometer and cooler, and heated to 80°C. Next, an emulsion was prepared by mixing 50 parts by mass of deionized water, 0.5 parts by mass of SR-10, 50.5 parts by mass of ST, 44 parts by mass of 2EHA, 3 parts by mass of AA, 2 parts by mass of HEMA and 0.5 parts by mass of DVB, and an aqueous solution prepared by dissolving 0.2 parts by mass of ammonium persulfate in 10 parts by mass of deionized water was simultaneously added dropwise over 3 hours to carry out polymerization, and then maintained at 80°C for 2 hours after the dropwise addition was completed. The mixture was then cooled to room temperature, the pH was adjusted to 7 with 25% aqueous ammonia, 1 part by mass of activide MBS and 0.1 parts by mass of activide MV4 were added, and the non-volatile content was adjusted to 40.0% with deionized water to obtain a binder composition for the negative electrode.

[0095] Comparative Example 2 A negative electrode composition, a negative electrode, a positive electrode composition, a positive electrode, and a secondary battery were obtained in the same manner as in Example 1, except that a negative electrode binder composition prepared by the method described below was used as the negative electrode binder composition. (1) Preparation of the negative electrode binder composition <Synthesis of emulsion A> 220 parts by mass of deionized water and 0.5 parts by mass of SR-10 were charged into a reaction vessel equipped with a stirrer, thermometer and cooler, and heated to 80°C. Next, an emulsion was prepared by mixing 50 parts by mass of deionized water, 0.5 parts by mass of SR-10, 26 parts by mass of ST, 68 parts by mass of 2EHA, and 6 parts by mass of AA. This emulsion was then simultaneously added dropwise over 3 hours to carry out polymerization, along with an aqueous solution prepared by dissolving 0.2 parts by mass of ammonium persulfate in 10 parts by mass of deionized water. Subsequently, the mixture was maintained at 80°C for 2 hours after the dropwise addition was completed. Afterward, the mixture was cooled to room temperature, the pH was adjusted to 7 with 25% aqueous ammonia, 1 part by mass of activide MBS and 0.1 parts by mass of activide MV4 were added, and then the non-volatile content was adjusted to 40.0% with deionized water to obtain emulsion A. <Synthesis of Emulsion B> 220 parts by mass of deionized water and 0.5 parts by mass of SR-10 were charged into a reaction vessel equipped with a stirrer, thermometer, and condenser, and heated to 80°C. Next, a mixture of 50 parts by mass of deionized water, 0.5 parts by mass of SR-10, 75 parts by mass of ST, 20 parts by mass of 2EHA, 4 parts by mass of HEMA, and 1 part by mass of DVB was simultaneously added dropwise over 3 hours to carry out polymerization, followed by maintaining the temperature at 80°C for 2 hours after the dropwise addition was completed. Subsequently, the mixture was cooled to room temperature, the pH was adjusted to 7 with 25% aqueous ammonia, 1 part by mass of actiside MBS and 0.1 parts by mass of actiside MV4 were added, and the non-volatile content was adjusted to 40.0% with deionized water to obtain emulsion B. <Preparation of blended emulsion> 50 parts of emulsion A and 50 parts of emulsion B were mixed and stirred at room temperature for 3 minutes to prepare a blended emulsion, which was used as the binder composition for the negative electrode.

[0096] Examples 2-40 and Comparative Examples 3-5: Except for using negative electrode binder compositions with modified material types and amounts as shown in Tables 1-4, negative electrode compositions, negative electrodes, positive electrodes, and secondary batteries were obtained in the same manner as in Example 1.

[0097] Example 41 Except for preparing the positive electrode composition in the same manner as in Example 1, the negative electrode composition, negative electrode, positive electrode composition, positive electrode, and secondary battery were obtained in the same manner as in Example 1, except that the type of material, the amount of material used, and the preparation procedure in "(4) Preparation of positive electrode composition" of Example 1 described above were changed as follows to prepare the positive electrode composition. (1) Preparation of positive electrode composition 94.0 parts by mass of olivine-type lithium iron phosphate (LiFePO4) as the positive electrode active material and 3.0 parts by mass of acetylene black as the conductive material were weighed out and stirred for 30 seconds in a rotation-orbit mixer (Thinky "ARE-310 (product name)"). Next, 48.0 parts by mass (0.96 parts by mass in terms of solids) of an aqueous solution (hereinafter referred to as "CMC solution") prepared by dissolving carboxymethylcellulose sodium salt ("Sunrose MAC350HC" manufactured by Nippon Paper Industries Co., Ltd.) in distilled water and adjusting the non-volatile content to 2% was added and mixed until the mixture became a paste, and then stirred in a rotary-orbit mixer for 2 minutes. Since heat was generated by stirring, it was cooled to room temperature with ice water, stirred again in a rotary-orbit mixer for 2 minutes, and then cooled to room temperature with ice water. Subsequently, 27.0 parts by mass (0.54 parts by mass in terms of solids) of the above CMC solution was added to this mixture and mixed until the mixture was homogenized, then stirred in a rotary-orbit mixer for 2 minutes, and cooled to room temperature with ice water. As a conductive additive, 7.5 parts by mass (0.07 parts by mass in terms of solids) of single-wall carbon nanotube aqueous dispersion ("TUBALL BATT H2O" manufactured by OCSiAl) was added and stirred in a rotary-orbit mixer for 2 minutes. 3.75 parts by mass (1.5 parts by mass in terms of solid content) of the negative electrode binder composition obtained in "(1) Preparation of negative electrode binder composition" of Example 1 above was added, and the mixture was stirred again in a rotary-orbit mixer for 2 minutes, and then cooled to room temperature with ice water. While measuring the viscosity of the obtained slurry with a B-type viscometer at 25°C and 30 rpm, distilled water was added until the viscosity was in the range of 10,000 to 12,000 mPa·s. Finally, the mixture was stirred in a rotary-orbit mixer for 30 seconds to prepare a slurry-like positive electrode composition.

[0098] [Evaluation] 1. Peel strength of electrodes Test pieces measuring 25 mm wide x 100 mm long were cut from the negative electrodes prepared in Examples 1 to 41 and Comparative Examples 1 to 5. The negative electrode active material side of the test piece was used as the adhesion surface and was attached to a stainless steel plate using double-sided tape (Nitto Denko Corporation "No. 5015"). On the other hand, approximately 10 mm of the copper foil edge was peeled off, and polyimide tape was attached there to serve as the attachment point for the peel test equipment (Shimadzu Corporation "Autograph AG-XPlus"). A 180° peel test was performed using the peel test machine and the peel strength was measured. In addition, the peel strength of the positive electrode prepared in Example 41 was measured in the same way as the negative electrode and was found to be 42 N / m.

[0099] 2. Battery Characteristics (Initial Charge / Discharge Efficiency and Capacity Retention Rate) The secondary batteries prepared in Examples 1 to 41 and Comparative Examples 1 to 5 were mounted on a charge / discharge device and left at 25°C for 3 hours. After that, one charge / discharge cycle was performed at 0.1C, and the initial charge / discharge efficiency was measured. Next, the charge / discharge cycle was repeated 50 times at 60°C and 0.2C. The discharge capacity retention rate after 50 cycles at 60°C (after 50 cycles) relative to the first discharge capacity at 0.2C (initial discharge capacity) was measured using the following formula: Capacity retention rate (%) = 100 × 50th discharge capacity (mAh / g) / Initial discharge capacity (mAh / g) The results are summarized in Tables 1 to 4.

[0100]

[0101]

[0102]

[0103]

[0104] The results in Tables 1-4 show that the electrode-forming material of the present invention, as an electrode binder composition, exhibits excellent film-forming properties. Furthermore, electrodes formed from the electrode-forming material of the present invention exhibit excellent durability against electrolytes, and secondary batteries equipped with such electrodes have a high initial charge-discharge efficiency of 90% or more, and moreover, a capacity retention rate of 90% or more, demonstrating an excellent balance of battery characteristics.

[0105] Example 42 (1) Preparation of material for electrode formation <Shell formation process> 220 parts by mass of deionized water and 0.5 parts by mass of SR-10 were charged into a reaction vessel equipped with a stirrer, thermometer and cooler, and heated to 80°C. Next, an emulsion was prepared by mixing 50 parts by mass of deionized water, 0.5 parts by mass of SR-10, 6 parts by mass of ST2, 68 parts by mass of 2EHA, and 6 parts by mass of AA. This emulsion and an aqueous solution prepared by dissolving 0.2 parts by mass of ammonium persulfate in 10 parts by mass of deionized water were simultaneously added dropwise to the reaction vessel over 3 hours to carry out polymerization. After the dropwise addition was completed, the temperature was maintained at 80°C for 2 hours. After that, it was cooled to room temperature, and the non-volatile content was adjusted to 26.0% with deionized water to obtain an emulsion in which polymer particles were dispersed in an aqueous medium (deionized water). <Core Formation Process> The reaction vessel was heated again to 80°C, and a mixture of 75 parts by mass of ST, 20 parts by mass of 2EHA, 4 parts by mass of HEMA, and 1 part by mass of DVB was simultaneously added dropwise to the reaction vessel over 3 hours to carry out polymerization. After the dropwise addition was complete, the temperature was maintained at 80°C for 2 hours. The mixture was cooled to room temperature, the pH was adjusted to 7 with 25% aqueous ammonia, 1 part by mass of activide MBS and 40.1 parts by mass of activide MV were added, and the non-volatile content was adjusted to 40.0% with deionized water to obtain the electrode forming material.

[0106] (2) Preparation of the negative electrode composition 48.75 parts by mass of artificial graphite and 48.75 parts by mass of natural graphite were weighed out as negative electrode active materials and stirred in a rotary-orbit mixer for 30 seconds. Next, 48.0 parts by mass (0.96 parts by mass in terms of solid content) of an aqueous solution (hereinafter referred to as "CMC solution") prepared by dissolving carboxymethylcellulose sodium salt (Sunrose MAC350HC manufactured by Nippon Paper Industries Co., Ltd.) in distilled water and adjusting the non-volatile content to 2% was added and mixed until the whole thing became a paste, and then stirred in a rotary-orbit mixer for 2 minutes. Since heat was generated by stirring, it was cooled to room temperature with ice water, stirred again in a rotary-orbit mixer for 2 minutes, and then cooled to room temperature with ice water. Subsequently, 27.0 parts by mass (0.54 parts by mass in terms of solid content) of the above CMC solution was added to this mixture and mixed until the whole thing became uniform, then stirred in a rotary-orbit mixer for 2 minutes, and then cooled to room temperature with ice water. 10 parts by weight of distilled water and 3.75 parts by mass (1.5 parts by mass in terms of solid content) of the electrode-forming material obtained in (1) above were added, and the mixture was stirred again in a rotary-orbit mixer for 2 minutes and cooled to room temperature with ice water. Distilled water was added while measuring the viscosity of the obtained slurry with a B-type viscometer at 25°C and 30 rpm so that it was in the range of 2000 to 4000 mPa·s. Finally, the mixture was stirred in a rotary-orbit mixer for 30 seconds to prepare a slurry-like negative electrode composition. (3) Preparation of composition for coating conductive substrate 84 parts of polyacrylic resin (5% solid content), which is a water-soluble binder, 4.5 parts of the electrode-forming material obtained in (1) above (40% solid content), 4 parts of conductive carbon black, and 7.5 parts of water were weighed and mixed uniformly by high-speed stirring at 2200 rpm / min for 10 min in a disperser to obtain a slurry-like conductive substrate coating composition (A). 15.2 parts (40% solids) of the electrode forming material obtained in (1) above, 6 parts of conductive carbon black, 33.8 parts (2% solids) of CMC aqueous solution, and 45 parts of water were weighed and mixed uniformly by high-speed stirring at 2200 rpm / min for 10 min in a disperser to obtain a slurry-like conductive substrate coating composition (B). (4) Current collector preparation The conductive substrate coating composition (A) obtained in (3) above was applied to aluminum foil using a coating machine and dried under conditions of 110°C to obtain carbon-coated aluminum foil as a positive electrode current collector in which the thickness of the carbon coating layer was controlled to 1 μm.The conductive substrate coating composition (B) obtained in (3) above was applied to the copper foil using a coating machine, and dried under conditions of 110°C to obtain a carbon-coated copper foil as a negative electrode current collector, in which the thickness of the carbon coating layer was controlled to 1 μm.

[0107] (5) The coating amount (surface density) of the negative electrode composition after drying of the negative electrode is 8.8 mg / cm². ２ The gap of the bar coater was adjusted so that the negative electrode composition obtained in (2) above was coated onto the carbon-coated copper foil used as the negative electrode current collector obtained in (4) above using this bar coater, and dried for 8 minutes in a forced-air dryer set to 80°C. The dried electrode was cut to a width of 40 mm and pressed using a roll press machine (Small Desktop Roll Press SA-602 manufactured by Tester Industries Co., Ltd.) to obtain a layer density of 1.55 g / cm³. ３ After pressing in this manner, the material was vacuum-dried at 110°C for 10 hours to obtain the negative electrode.

[0108] (6) Preparation of the positive electrode composition As the positive electrode active material, olivine-type lithium iron phosphate (LiFePO) ４ 94.0 parts by mass of ) and 3.0 parts by mass of acetylene black as a conductive material were weighed out and stirred for 30 seconds in a rotating-orbit mixer (Thinky "ARE-310 (product name)") at a rotation speed of 1000 rpm and an orbital speed of 2000 rpm. Thereafter, stirring using the rotating-orbital mixer was performed using the same apparatus and conditions unless otherwise specified. Next, 2.16 parts by mass of polyvinylidene fluoride (PVDF) and 19.0 parts by mass of NMP were added and mixed until the mixture became a paste, then stirred in the rotating-orbital mixer for 2 minutes. Since the mixture generated heat during stirring, it was cooled to room temperature in ice water, stirred again in the rotating-orbital mixer for 2 minutes, and then cooled to room temperature in ice water. Subsequently, 0.84 parts by mass of polyvinylidene fluoride (PVDF) and 5 parts by mass of NMP were added to this mixture and mixed until the mixture was homogenized. The viscosity of the obtained slurry was measured using a B-type viscometer at 25°C and 30 rpm, and NMP was added to bring it within the range of 2000 to 4000 mPa·s. Finally, the mixture was stirred for 30 seconds in a rotational mixer to prepare a slurry-like cathode composition.

[0109] (7) The coating amount (surface density) of the cathode composition after the preparation and drying of the cathode is 25.0 mg / cm².２ The gap of the bar coater was adjusted so that the positive electrode composition obtained in (6) above was coated onto the carbon-coated aluminum foil used as the positive electrode current collector obtained in (4) above using this bar coater, and dried for 10 minutes in a forced-air dryer set to 80°C. The dried electrode was cut to a width of 40 mm and pressed using a roll press machine (Small Desktop Roll Press SA-602 manufactured by Tester Industries Co., Ltd.) to obtain a layer density of 2.5 g / cm³. ３ After pressing in this manner, the cathode was obtained by vacuum drying at 110°C for 10 hours.

[0110] (8) Fabrication of a secondary battery The negative electrode fabricated above was cut into a 24 mm x 24 mm square with a tab, and the positive electrode fabricated above was cut into a 22 mm x 22 mm square with a tab, using a die-cutting blade. Nickel tab leads were welded to the tab portion of the cut electrodes, and aluminum tab leads were welded to the tab portion of the negative electrode, and aluminum tab leads were welded to the tab portion of the positive electrode. Meanwhile, a 25 μm thick polyethylene microporous membrane was cut into a 28 mm x 3.8 cm rectangle using a die-cutting blade as a separator. The positive and negative electrodes were placed facing each other with this separator in between, wrapped in laminate film, and the tab portion was fixed by heat sealing. Then, LiPF ６ The non-aqueous electrolyte solution obtained by dissolving the compound in a 30 / 30 / 40 mixed solution of ethylene carbonate / dimethyl carbonate / methyl ethyl carbonate (volume ratio) at a concentration of 1 mol / L, and then adding 1 vol% vinyl carbonate and 5 vol% fluoroethylene carbonate, was prepared by adding 300 μL of this solution and completely sealing it by vacuum lamination to produce the laminate-type secondary battery of Example 1.

[0111] Comparative Example 6 A negative electrode composition, a conductive substrate coating composition, a current collector, a negative electrode, a positive electrode composition, a positive electrode, and a secondary battery were obtained in the same manner as in Example 42, except that an electrode forming material prepared by the method described below was used as the electrode forming material. (1) Preparation of electrode forming material 220 parts by mass of deionized water and 0.5 parts by mass of SR-10 were charged into a reaction vessel equipped with a stirrer, thermometer and cooler, and heated to 80°C. Next, an emulsion was prepared by mixing 50 parts by mass of deionized water, 0.5 parts by mass of SR-10, 50.5 parts by mass of ST, 44 parts by mass of 2EHA, 3 parts by mass of AA, 2 parts by mass of HEMA and 0.5 parts by mass of DVB, and an aqueous solution prepared by dissolving 0.2 parts by mass of ammonium persulfate in 10 parts by mass of deionized water was simultaneously added dropwise over 3 hours to carry out polymerization, and then maintained at 80°C for 2 hours after the dropwise addition was completed. The mixture was then cooled to room temperature, the pH was adjusted to 7 with 25% aqueous ammonia, 1 part by mass of activide MBS and 0.1 parts by mass of activide MV4 were added, and the non-volatile content was adjusted to 40.0% with deionized water to obtain the electrode forming material.

[0112] Comparative Example 7 Except for using an electrode-forming material prepared by the method described below as the electrode-forming material, a negative electrode composition, a conductive substrate coating composition, a current collector, a negative electrode, a positive electrode composition, a positive electrode, and a secondary battery were obtained in the same manner as in Example 42. (1) Preparation of electrode-forming material <Synthesis of emulsion A> 220 parts by mass of deionized water and 0.5 parts by mass of SR-10 were charged into a reaction vessel equipped with a stirrer, thermometer, and cooler, and heated to 80°C. Next, an emulsion was prepared by mixing 50 parts by mass of deionized water, 0.5 parts by mass of SR-10, 26 parts by mass of ST, 68 parts by mass of 2EHA, and 6 parts by mass of AA, and an aqueous solution prepared by dissolving 0.2 parts by mass of ammonium persulfate in 10 parts by mass of deionized water was simultaneously added dropwise over 3 hours to carry out polymerization, and then maintained at 80°C for 2 hours after the dropwise addition was completed. Afterward, the mixture was cooled to room temperature, the pH was adjusted to 7 with 25% aqueous ammonia, 1 part by mass of activide MBS and 0.1 parts by mass of activide MV4 were added, and then the non-volatile content was adjusted to 40.0% with deionized water to obtain emulsion A. <Synthesis of Emulsion B> 220 parts by mass of deionized water and 0.5 parts by mass of SR-10 were charged into a reaction vessel equipped with a stirrer, thermometer, and condenser, and heated to 80°C. Next, a mixture of 50 parts by mass of deionized water, 0.5 parts by mass of SR-10, 75 parts by mass of ST, 20 parts by mass of 2EHA, 4 parts by mass of HEMA, and 1 part by mass of DVB was simultaneously added dropwise over 3 hours to carry out polymerization, followed by maintaining the temperature at 80°C for 2 hours after the dropwise addition was completed. Subsequently, the mixture was cooled to room temperature, the pH was adjusted to 7 with 25% aqueous ammonia, 1 part by mass of activide MBS and 0.1 parts by mass of activide MV4 were added, and the non-volatile content was adjusted to 40.0% with deionized water to obtain emulsion B. <Preparation of blended emulsion> 50 parts of emulsion A and 50 parts of emulsion B were mixed and stirred at room temperature for 3 minutes to prepare a blended emulsion which was used as the electrode forming material.

[0113] Examples 43 to 81 and Comparative Examples 8 to 10: Except for using electrode-forming materials with modified material types and proportions as shown in Tables 5 to 8, a negative electrode composition, a conductive substrate coating composition, a current collector, a negative electrode, a positive electrode composition, a positive electrode, and a secondary battery were obtained in the same manner as in Example 42.

[0114] [Evaluation] 1. Peel strength of electrodes 1-1) Peel strength of positive electrode Test pieces measuring 25 mm wide x 100 mm long were cut from the positive electrodes prepared in Examples 42 to 81 and Comparative Examples 6 to 10. The positive electrode active material side of the test piece was used as the adhesion surface and was attached to a stainless steel plate using double-sided tape (Nitto Denko Corporation "No. 5015"). On the other hand, approximately 10 mm of the edge of the carbon-coated aluminum foil was peeled off, and polyimide tape was attached there to serve as the attachment point for the peel test equipment (Shimadzu Corporation "Autograph AG-XPlus"). A 180° peel test was performed using the peel test machine, and the peel strength was measured. 1-2) Peel Strength of the Negative Electrode Test pieces measuring 25 mm wide x 100 mm long were cut from the negative electrodes prepared in Examples 42-81 and Comparative Examples 6-10. The negative electrode active material side of the test piece was used as the adhesion surface and was attached to a stainless steel plate using double-sided tape (Nitto Denko Corporation "No. 5015"). On the other hand, approximately 10 mm of the edge of the carbon-coated copper foil was peeled off, and polyimide tape was attached there to serve as the attachment point for the peel test equipment (Shimadzu Corporation "Autograph AG-XPlus"). A 180° peel test was performed using the peel test machine, and the peel strength was measured.

[0115] 2. Battery Characteristics (Initial Charge / Discharge Efficiency and Capacity Retention Rate) The secondary batteries prepared in Examples 42-81 and Comparative Examples 6-10 were mounted on a charge / discharge device and left at 25°C for 3 hours. After that, one charge / discharge cycle was performed at 0.1C, and the initial charge / discharge efficiency was measured. Next, the charge / discharge cycle was repeated 50 times at 60°C and 0.2C. The discharge capacity retention rate after 50 cycles at 60°C (after 50 cycles) relative to the first discharge capacity at 0.2C (initial discharge capacity) was measured using the following formula: Capacity retention rate (%) = 100 × 50th discharge capacity (mAh / g) / Initial discharge capacity (mAh / g) The results are summarized in Tables 5-8.

[0116]

[0117]

[0118]

[0119]

[0120] The results in Tables 5 to 8 show that the adhesion strength between the current collector having a coating layer (carbon coating layer) formed from the conductive substrate coating composition of the present invention and the electrode material layer is excellent. Furthermore, secondary batteries equipped with electrodes formed from current collectors having such coating layers have a high initial charge / discharge efficiency of 90% or more, and moreover, a capacity retention rate of 90% or more, indicating an excellent balance of battery characteristics.

[0121] The electrode-forming material of the present invention exhibits excellent durability to electrolytes (electrolyte resistance) and film-forming properties, enabling the formation of electrodes and secondary batteries with excellent battery characteristics such as charge-discharge efficiency and capacity retention. Secondary batteries equipped with such electrodes have excellent battery characteristics such as charge-discharge characteristics and can be effectively used in portable electronic devices, for example, as paper batteries, button batteries, coin batteries, stacked batteries, cylindrical batteries, prismatic batteries, etc.

Claims

1. A non-aqueous secondary battery electrode forming material comprising core-shell type particles (A) having a shell portion made of polymer (a1) and a core portion made of polymer (a2), and an aqueous medium (B), wherein the polymer (a1) contains structural units derived from a reactive emulsifier, structural units derived from a vinyl monomer having an acidic group, and structural units derived from a (meth)acrylic acid ester monomer, and the polymer (a2) contains structural units derived from a vinyl monomer having a crosslinkable reactive group and structural units derived from an aromatic vinyl monomer.

2. The material for forming an electrode in a non-aqueous secondary battery according to claim 1, wherein the reactive emulsifier is an emulsifier having an ethylenically unsaturated group.

3. The material for forming electrodes for a non-aqueous secondary battery according to claim 1, wherein the content of structural units derived from the reactive emulsifier is 0.01% by mass or more and 3% by mass or less, relative to the total amount obtained by excluding the structural units derived from the reactive emulsifier from the units constituting the polymer (a1).

4. The material for forming electrodes for a non-aqueous secondary battery according to claim 1, wherein the content of structural units derived from the acidic vinyl monomer is 0.1% by mass or more and 10% by mass or less, relative to the total amount obtained by excluding the structural units derived from the reactive emulsifier from the units constituting the polymer (a1).

5. The non-aqueous secondary battery electrode forming material according to claim 1, wherein the polymer (a1) further contains structural units derived from aromatic vinyl monomers.

6. The non-aqueous secondary battery electrode forming material according to claim 1, wherein the polymer (a1) further contains structural units derived from a vinyl monomer having an amide group.

7. The non-aqueous secondary battery electrode forming material according to claim 1, wherein the crosslinkable reactive group is at least one selected from an ethylenically unsaturated group, a monofunctional or polyfunctional alkoxysilyl group, a methylol group, and an alkyloxymethyl group.

8. The non-aqueous secondary battery electrode forming material according to claim 1, wherein the content of structural units derived from the vinyl monomer having the crosslinkable reactive group is 0.1% by mass or more and 10% by mass or less, relative to the total amount of units constituting the polymer (a2).

9. The non-aqueous secondary battery electrode forming material according to claim 1, wherein the polymer (a2) further contains structural units derived from (meth)acrylic acid ester monomers.

10. The non-aqueous secondary battery electrode forming material according to claim 1, wherein the polymer (a2) further contains structural units derived from a vinyl monomer having a cyano group.

11. The non-aqueous secondary battery electrode forming material according to claim 1, wherein the polymer (a2) does not contain structural units derived from a vinyl monomer having an acidic group.

12. The non-aqueous secondary battery electrode forming material according to claim 1, wherein the polymer (a2) does not contain structural units derived from fluorine-containing monomers.

13. A binder composition for non-aqueous secondary battery electrodes, as described in any one of claims 1 to 12.

14. A method for producing a non-aqueous secondary battery electrode forming material comprising a core-shell type particle (A) having a shell portion made of polymer (a1) and a core portion made of polymer (a2), and an aqueous medium (B), the method comprising: a shell portion forming step of polymerizing a vinyl monomer having an acidic group and a (meth)acrylic acid ester monomer in the aqueous medium (B) in the presence of a reactive emulsifier to form polymer particles that will become the shell portion made of polymer (a1); and a core portion forming step of polymerizing a vinyl monomer having a crosslinkable reactive group and an aromatic vinyl monomer using the polymer particles as a reaction field to form the core portion made of polymer (a2) inside the polymer particles.

15. A composition for a non-aqueous secondary battery electrode, comprising an active material and the non-aqueous secondary battery electrode forming material described in claim 13.

16. A non-aqueous secondary battery electrode comprising a current collector and an electrode material layer formed using the non-aqueous secondary battery electrode composition described in claim 15.

17. A non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein at least one of the positive electrode and the negative electrode is the non-aqueous secondary battery electrode described in claim 16.

18. A composition for coating a conductive substrate, comprising a conductive material and a non-aqueous secondary battery electrode forming material according to any one of claims 1 to 12.

19. A current collector having a coating layer formed on one or both sides of a sheet-like conductive substrate using the conductive substrate coating composition described in claim 18.

20. A non-aqueous secondary battery electrode comprising the current collector described in claim 19.

21. A non-aqueous secondary battery comprising the non-aqueous secondary battery electrode described in claim 20.

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