Non-aqueous secondary battery electrode binder, non-aqueous secondary battery electrode binder composition, and non-aqueous secondary battery electrode

Abstract

A non-aqueous secondary battery electrode adhesive is provided that effectively improves the peel strength of the electrode active material layer to the current collector, which can help reduce the internal resistance of the battery and improve its cycle characteristics. The non-aqueous secondary battery electrode adhesive of the present invention comprises copolymer (A) and copolymer (B). The copolymer (A) has 11 to 13 structural units derived from monomers (a1), (a2) having olefinic unsaturated bonds and an internal crosslinking agent (a3). The copolymer (B) has 5.0 mol% to 98 mol% and 0.30 mol% to 90 mol% and 0.30 mol% to 10 mol% of structural units 21 to 23 as shown in formulas (1) to (3) in all structural units. (In formula (2), R 1 It can be an alkyl group with 1 or more but less than 6 carbon atoms that can have branches. In formula (3), R 2 (A group containing an olefinic unsaturated bond.)

Description

Technical Field

[0001] This invention relates to non-aqueous secondary battery electrode adhesives, non-aqueous secondary battery electrode adhesive compositions, and non-aqueous secondary battery electrodes.

[0002] This application claims priority based on Japanese Patent Application No. 2020-214882 filed on December 24, 2020, the contents of which are incorporated herein by reference. Background Technology

[0003] Non-aqueous secondary batteries typically include a positive electrode (using a metal oxide or similar material as the positive electrode active material), a negative electrode (using a material such as graphite as the negative electrode active material), and an electrolyte. Non-aqueous secondary batteries are secondary batteries that charge and discharge by the movement of ions, which act as charge carriers, between the positive and negative electrodes.

[0004] Lithium-ion batteries are a prime example of non-aqueous secondary batteries. Considering miniaturization and weight reduction, non-aqueous secondary batteries are used as power sources for laptops, mobile phones, power tools, and electronic / communication devices. Furthermore, recently, from the perspective of environmentally friendly vehicle applications, they are also being used in electric vehicles and hybrid vehicles. There is a strong demand for high output, high capacity, and long lifespan in non-aqueous secondary batteries.

[0005] The adhesives used for the positive and negative electrodes serve to bond the active electrode materials together and to bond them to the current collector. To improve the capacity of non-aqueous secondary batteries and protect the operating environment, aqueous dispersion adhesives have been developed. For example, styrene-butadiene rubber (SBR) based aqueous dispersions using carboxymethyl cellulose (CMC) as a thickener are known.

[0006] Patent Document 1 describes a method for polymerizing ethylene oxide, olefin oxide other than ethylene oxide, alkyl glycidyl ether, allyl glycidyl ether, or combinations thereof. The method also describes that compositions comprising the copolymers obtained by polymerization can be used as binder materials in battery electrodes containing electroactive particles.

[0007] Patent Document 2 describes a secondary battery negative electrode having an electrode layer, wherein the electrode layer comprises: a copolymer obtained from (meth)acrylate and a vinyl monomer having an acid component; and at least one selected from polyoxyethylene alkyl ether derivatives, polyoxyethylene-polyoxypropylene condensates, and polyoxyethylene-polyoxypropylene alkyl ether derivatives.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Publication No. 2012-517519

[0011] Patent Document 2: Japanese Patent Application Publication No. 2014-239070 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] However, in the components described in Patent Documents 1 and 2, when used as an electrode adhesive, there is room for improving the peel strength of the electrode active material layer to the current collector and for reducing the internal resistance when manufacturing a battery.

[0014] The purpose of this invention is to provide a non-aqueous secondary battery electrode adhesive, a non-aqueous secondary battery electrode adhesive composition, and a non-aqueous secondary battery electrode that effectively improves the peel strength of the electrode active material layer to the current collector in non-aqueous secondary batteries, which can help reduce the internal resistance and improve the cycle characteristics of the battery.

[0015] Methods for solving problems

[0016] In order to solve the above problems, the present invention is as follows [1] to

[14] .

[0017] [1] A non-aqueous secondary battery electrode adhesive, characterized in that it comprises copolymer (A) and copolymer (B),

[0018] The copolymer (A) described above is a polymer of a compound having olefinic unsaturated bonds.

[0019] The copolymer (A) described above has an 11th structural unit derived from monomer (a1) and a 12th structural unit derived from monomer (a2); or, it has an 11th structural unit derived from monomer (a1), a 12th structural unit derived from monomer (a2), and a 13th structural unit derived from internal crosslinking agent (a3).

[0020] The aforementioned monomer (a1) is a nonionic compound containing olefinic unsaturated bonds, lacking both hydroxyl and cyano groups, and without multiple independent olefinic unsaturated bonds.

[0021] The monomer (a2) described above is a compound containing olefinic unsaturated bonds and anionic functional groups, but not multiple independent olefinic unsaturated bonds.

[0022] The aforementioned internal crosslinking agent (a3) ​​is a compound having multiple independent olefinic unsaturated bonds, capable of forming a crosslinked structure in the free radical polymerization of monomers containing the aforementioned monomers (a1) and (a2).

[0023] In the copolymer (A) described above, the content of the 12th structural unit is 1.0 part by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the 11th structural unit.

[0024] In the copolymer (A) described above, the content of the 13th structural unit is 0 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the 11th structural unit.

[0025] The copolymer (B) described above has 5.0 mol% or more and 98 mol% or less of the 21st structural unit shown in formula (1) in all structural units, 0.30 mol% or more and 90 mol% or less of the 22nd structural unit shown in formula (2) in all structural units, and 0.30 mol% or more and 10 mol% or less of the 23rd structural unit shown in formula (3) in all structural units.

[0026] The total content of the above-mentioned structural unit 21, structural unit 22, and structural unit 23 in all structural units of the copolymer (B) is 90% by mass or more.

[0027] The mass ratio of the content of copolymer (A) to the content of copolymer (B) is 50.0 / 50.0 or more and 99.0 / 1.0 or less.

[0028]

[0029] (In equation (2), R) 1 (This refers to alkyl groups that can have 1 or more but less than 6 carbon atoms and can have branched chains.)

[0030]

[0031] (In equation (3), R) 2 (A group containing an olefinic unsaturated bond.)

[0032] [2] According to the non-aqueous secondary battery electrode adhesive described in [1], the copolymer (B) comprises

[0033] The above-mentioned structural unit 21 contains 5.0 mol% or more and 50 mol% or less.

[0034] The aforementioned structural unit 22 is 40 mol% or more and 90 mol% or less.

[0035] The above-mentioned structural unit 23 is 0.30 mol% or more and 10 mol% or less.

[0036] [3] According to the non-aqueous secondary battery electrode adhesive described in [1], the copolymer (B) comprises

[0037] The aforementioned structural unit 21 is 70 mol% or more and 98 mol% or less.

[0038] The above-mentioned structural unit 22 is 0.30 mol% or more and 20 mol% or less.

[0039] The above-mentioned structural unit 23 is 0.30 mol% or more and 10 mol% or less.

[0040] [4] According to any one of [1] to [3], the non-aqueous secondary battery electrode adhesive, in the above formula (3), R 2 It has at least one selected from vinyloxy, allyloxy, (meth)acryloyl, (meth)acryloyloxy, and -OCH2-CH2-CH2=CH2.

[0041] [5] According to any one of [1] to [4], the non-aqueous secondary battery electrode adhesive, in the above formula (3), R 2 It is represented by the following formula (4).

[0042] -R 21 -R 22 (4)

[0043] (In equation (4), R) 21 R can be an alkylene group having 1 to 5 carbon atoms and branched chains. 22 It is a functional group selected from vinyloxy, allyloxy, (meth)acryloyl, and (meth)acryloyloxy.

[0044] [6] The non-aqueous secondary battery electrode adhesive according to any one of [1] to [5], wherein the copolymer (B) is a block copolymer having a first block containing a 21st structural unit, a second block containing a 22nd structural unit, and a third block containing a 23rd structural unit.

[0045] [7] The non-aqueous secondary battery electrode adhesive according to any one of [1] to [6], wherein the monomer (a1) does not have polar functional groups.

[0046] [8] The non-aqueous secondary battery electrode binder according to any one of [1] to [7], wherein the monomer (a2) is a compound having at least one of carboxyl group and sulfonyl group.

[0047] [9] The non-aqueous secondary battery electrode adhesive according to any one of [1] to [8], wherein the copolymer (A) comprises the above-mentioned 11 structural unit and the above-mentioned 12 structural unit in total of 80% by mass or more.

[0048]

[10] In the non-aqueous secondary battery electrode adhesive according to any one of [1] to [9], the content of the 13th structural unit in the copolymer (A) is 0.050 parts by mass or more relative to 100 parts by mass of the 11th structural unit.

[0049]

[11] A non-aqueous secondary battery electrode adhesive composition comprising any one of [1] to

[10] a non-aqueous secondary battery electrode adhesive and an aqueous medium.

[0050]

[12] A non-aqueous secondary battery electrode slurry, comprising the non-aqueous secondary battery electrode binder, electrode active material, and aqueous medium as described in any one of [1] to

[10] ,

[0051] The aqueous medium is selected from water, hydrophilic solvents, and mixtures containing water and hydrophilic solvents.

[0052]

[13] A non-aqueous secondary battery electrode comprising any one of the non-aqueous secondary battery electrode adhesives described in [1] to

[10] .

[0053]

[14] A non-aqueous secondary battery comprising the non-aqueous secondary battery electrode described in

[13] .

[0054] The effects of the invention

[0055] According to the present invention, a non-aqueous secondary battery electrode adhesive, a non-aqueous secondary battery electrode adhesive composition, and a non-aqueous secondary battery electrode can be provided to effectively improve the peel strength of the electrode active material layer to the current collector in a non-aqueous secondary battery, which can help reduce the internal resistance and improve the cycle characteristics of the battery. Detailed Implementation

[0056] Hereinafter, as embodiments of the present invention, non-aqueous secondary battery electrode adhesive (also known as adhesive for non-aqueous secondary battery electrodes), non-aqueous secondary battery electrode adhesive composition (also known as adhesive composition for non-aqueous secondary battery electrodes), non-aqueous secondary battery electrode slurry (also known as slurry for non-aqueous secondary battery electrodes), non-aqueous secondary battery electrode, and non-aqueous secondary battery will be described.

[0057] The term "(meth)acryloyl" is a general term for acryloyl and methacryloyl groups, and the term "(meth)acrylate" refers to a general term for acrylates and methacrylates.

[0058] "Non-volatile component" refers to the component remaining after weighing 1g of the composition in a 5cm diameter aluminum dish and drying it at 105°C for 1 hour under 1 atmosphere (1013hPa) with air circulation in a desiccator. The composition can be in the form of a solution, dispersion, or slurry, but is not limited to these. "Non-volatile component concentration" is the ratio (mass%) of the mass of the non-volatile component after drying under the above conditions to the mass (1g) of the composition before drying.

[0059] Unless otherwise specified, the term "olefin unsaturated bond" refers to an olefin unsaturated bond that is capable of free radical polymerization.

[0060] In polymers containing compounds with olefinic unsaturated bonds, the chemical structure of the portion of a structural unit derived from a compound having olefinic unsaturated bonds, excluding the olefinic unsaturated bonds, is identical to the chemical structure of the portion of that structural unit in the polymer, excluding the portion corresponding to the olefinic unsaturated bonds. For example, a structural unit derived from acrylic acid has the structure -CH2CH(COOH)- in the polymer.

[0061] Furthermore, for compounds with multiple independent olefinic unsaturated bonds, these bonds can remain as structural units of the polymer. Multiple independent olefinic unsaturated bonds refer to multiple olefinic unsaturated bonds that do not form conjugated dienes with each other. For example, structural units derived from divinylbenzene can be structures without any olefinic unsaturated bonds (where all portions corresponding to the olefinic unsaturated bonds are introduced into the polymer chain) or structures with one olefinic unsaturated bond (where only the portion corresponding to one olefinic unsaturated bond is introduced into the polymer chain).

[0062] Furthermore, if the chemical structure of the monomer does not correspond to the chemical structure of the polymer after polymerization, such as by subjecting the portion of the monomer other than the chain corresponding to the olefinic unsaturated bond to a chemical reaction, the chemical structure after polymerization is used as the reference. For example, in the case of polymerizing vinyl acetate and then saponifying it, the chemical structure of the polymer is considered as the reference, and the structural units are derived from vinyl alcohol rather than vinyl acetate.

[0063] <1. Non-aqueous secondary battery electrode adhesive>

[0064] The non-aqueous secondary battery electrode adhesive of the present invention comprises copolymer (A) and copolymer (B). Hereinafter, unless otherwise specified, electrode adhesive refers to the non-aqueous secondary battery electrode adhesive of the present invention. The electrode adhesive may contain other components, for example, polymers other than copolymer (A) and copolymer (B). The non-aqueous secondary battery electrode adhesive of the present invention is preferably composed of copolymer (A) and copolymer (B).

[0065] The copolymers (A) and (B) are described in detail below.

[0066] [1-1. Copolymer (A)]

[0067] The copolymer (A) is a polymer of a compound having olefinically unsaturated bonds. The copolymer (A) has an 11th structural unit derived from monomer (a1) and a 12th structural unit derived from monomer (a2). The copolymer (A) may further have a 13th structural unit derived from an internal crosslinking agent (a3). The copolymer (A) may contain structural units from other monomers (a4) that do not conform to any of monomers (a1), monomer (a2), and internal crosslinking agent (a3). Details of each monomer and internal crosslinking agent are described below.

[0068] [1-1-1. Monomer (a1)]

[0069] The monomer (a1) is a nonionic compound having olefinic unsaturated bonds but not having multiple independent olefinic unsaturated bonds (neither anionic nor cationic functional groups). Preferably, the monomer (a1) does not have a polyoxyalkylene structure.

[0070] The monomer (a1) has neither a hydroxyl group nor a cyano group. The monomer (a1) preferably does not have a polar functional group. The monomer (a1) may contain only one compound or two or more compounds. The monomer (a1) is preferably at least one of a (meth)acrylate without a polar functional group and an aromatic vinyl compound, more preferably containing both. The (meth)acrylate without a polar functional group further preferably contains an alkyl (meth)acrylate. The total content of the monomer (a1), the alkyl (meth)acrylate, and the aromatic vinyl compound is further preferably 80% by mass or more, more preferably 90% by mass or more, and most preferably 100% by mass.

[0071] Furthermore, regarding the composition of the monomer (a1), in order to adjust the glass transition temperature of the copolymer (A) or to adjust the polymerization rate corresponding to the molecular design, it is preferable to appropriately adjust the preferred compound and its amount within the range specified in this invention.

[0072] Examples of alkyl methacrylates include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, lauryl methacrylate, stearyl methacrylate, etc.

[0073] Here, the aromatic vinyl compound does not contain a (meth)acryloyl group. Examples of aromatic vinyl compounds include styrene, tert-butylstyrene, α-methylstyrene, p-methylstyrene, and 1,1-diphenylethylene. When the monomer (a1) contains an aromatic vinyl compound, the monomer (a1) more preferably contains at least one of styrene and α-methylstyrene, and more preferably contains styrene.

[0074] The monomer (a1) may contain multiple olefinic unsaturated bonds that form a conjugated diene with each other. Examples of compounds having multiple olefinic unsaturated bonds that form a conjugated diene with each other include, for example, 1,3-butadiene and 1,3-pentadiene.

[0075] [1-1-2. Monomer (a2)]

[0076] Monomer (a2) is a compound having an olefinic unsaturated bond and an anionic functional group. Monomer (a2) does not have multiple independent olefinic unsaturated bonds. Monomer (a2) preferably does not have a polyoxyalkylene structure. Examples of anionic functional groups include carboxyl, sulfonyl, and phosphate groups. Furthermore, the anionic functional group can form a salt. Monomer (a2) preferably comprises a compound having at least one of a carboxyl group and a sulfonyl group, and more preferably a compound having a carboxyl group.

[0077] Monomer (a2) may contain only one compound or two or more compounds. Monomer (a2) may contain compounds having multiple identical anionic functional groups in one molecule. That is, copolymer (A) may contain multiple identical anionic functional groups in one structural unit. Monomer (a2) may contain compounds having two or more different anionic functional groups in one molecule. That is, copolymer (A) may contain two or more different anionic functional groups in one structural unit. Furthermore, monomer (a2) may contain two or more compounds containing different anionic functional groups. That is, copolymer (A) may contain two or more structural units containing different anionic functional groups.

[0078] Examples of monomers (a2) include unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; half-esters of unsaturated dicarboxylic acids; and p-styrene sulfonic acid. Among these, monomer (a2) preferably contains at least one of (meth)acrylic acid and itaconic acid.

[0079] At least a portion of the structural unit derived from monomer (a2) can form a salt with a basic substance. Examples of monomers (a2) that form salts include sodium (meth)acrylate and sodium p-styrene sulfonate.

[0080] The monomer (a2) preferably comprises at least one of a sulfonic acid having an olefinic unsaturated bond and its salt, more preferably a sulfonate having an olefinic unsaturated bond. As a sulfonic acid, it preferably comprises an aromatic vinyl compound having a sulfonyl group, more preferably p-styrene sulfonic acid. As a sulfonate, it preferably comprises a salt of an aromatic vinyl compound having a sulfonyl group, more preferably p-styrene sulfonate, and even more preferably sodium p-styrene sulfonate. This is because the formation of coarse particles can be suppressed in the electrode binder composition described later.

[0081] [1-1-3. Internal cross-linking agent (a3)]

[0082] The internal crosslinking agent (a3) ​​is a compound having multiple independent olefinic unsaturated bonds and capable of forming a crosslinked structure in the free radical polymerization of monomers including monomers (a1) and (a2). Examples of such compounds include divinylbenzene, ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 2-hydroxy-3-acryloyloxypropyl methacrylate.

[0083] [1-1-4. Other monomers (a4)]

[0084] Regarding other monomers (a4), none of them are found to be monomers (a1) to (a3). Examples of other monomers (a4) include compounds having olefinic unsaturated bonds and polar functional groups, surfactants having olefinic unsaturated bonds (hereinafter sometimes referred to as "polymeric surfactants"), compounds having olefinic unsaturated bonds and functioning as silane coupling agents, etc., but are not limited to these.

[0085] As a polar functional group, it is preferred to include at least one of hydroxyl and cyano groups. Examples of monomers having olefinic unsaturated bonds and polar functional groups include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl acrylate, and (meth)acrylonitrile. The copolymer (A) preferably contains structural units derived from compounds containing olefinic unsaturated bonds and hydroxyl groups, more preferably from (meth)acrylates having hydroxyl groups, and even more preferably from 2-hydroxyethyl (meth)acrylates.

[0086] As polymerizable surfactants, compounds having olefinic unsaturated bonds and having the function of surfactants can be exemplified by compounds shown in the following chemical formulas (6) to (9).

[0087]

[0088] In equation (6), R 3 Preferably alkyl, p is preferably an integer from 10 to 40. R 3 The number of carbon atoms is more preferably 10 to 40, R3 Further preferred are straight-chain unsubstituted alkyl groups with 10 to 40 carbon atoms.

[0089]

[0090] In equation (7), R 4 Preferably alkyl, q is preferably an integer from 10 to 12. R 4 The number of carbon atoms is more preferably 10 to 40, R 4 Further preferred are straight-chain unsubstituted alkyl groups with 10 to 40 carbon atoms.

[0091]

[0092] In equation (8), R 5 Preferably alkyl, M 1 Preferably, NH4 or Na. R 5 The number of carbon atoms is more preferably 10 to 40, R 5 Further preferred are straight-chain unsubstituted alkyl groups with 10 to 40 carbon atoms.

[0093]

[0094] In equation (9), R 6 Preferably alkyl, M 2 Preferably, NH4 or Na. R 6 The number of carbon atoms is more preferably 10 to 40, R 6 Further preferred are straight-chain unsubstituted alkyl groups with 10 to 40 carbon atoms.

[0095] Examples of compounds that have olefinic unsaturated bonds and function as silane coupling agents include vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltriethoxysilane.

[0096] [1-1-5. Content of each structural unit in copolymer (A)]

[0097] In copolymer (A), the content of the 12th structural unit derived from monomer (a2) is 1.0 part by mass or more, preferably 2.0 part by mass or more, and more preferably 3.5 part by mass or more, relative to 100 parts by mass of the 11th structural unit derived from monomer (a1). This is because the mechanical stability of the electrode adhesive is improved. Furthermore, it is because the peel strength of the electrode active material layer containing the electrode adhesive of the present invention is improved.

[0098] In copolymer (A), the content of the 12th structural unit derived from monomer (a2) is 30 parts by mass or less, preferably 15 parts by mass or less, and more preferably 7.5 parts by mass or less, relative to 100 parts by mass of the 11th structural unit derived from monomer (a1). This is because it suppresses the gelation of the electrode adhesive. Furthermore, it is because it improves the mechanical stability of the electrode adhesive.

[0099] The combined mass percentage of the 11th and 12th structural units in the copolymer (A) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. This is because by increasing the content of these structural units, the effects obtained by the present invention are further enhanced.

[0100] When the copolymer (A) contains a 13th structural unit derived from the internal crosslinking agent (a3), the content of the 13th structural unit derived from the internal crosslinking agent (a3) ​​is 0 parts by mass or more, preferably 0.050 parts by mass or more, more preferably 0.075 parts by mass or more, and even more preferably 0.50 parts by mass or more, relative to 100 parts by mass of the 11th structural unit derived from the monomer (a1). This is because it can suppress the deterioration of the electrode binder and improve the cycle characteristics (discharge capacity retention) of batteries using electrodes having an electrode active material layer containing the electrode binder of the present invention.

[0101] When the copolymer (A) contains structural units derived from the internal crosslinking agent (a3), the content of the 13th structural unit derived from the internal crosslinking agent (a3) ​​is 20 parts by mass or less, preferably 7.5 parts by mass or less, and more preferably 2.5 parts by mass or less, relative to 100 parts by mass of the 11th structural unit derived from the monomer (a1). This is to suppress the gelation of the electrode adhesive.

[0102] [1-1-6. Glass transition temperature of copolymer (A)]

[0103] The glass transition temperature Tg of copolymer (A) is the peak temperature of the DDSC plot obtained by DSC measurement using Hitachi High Tech Sciences EXSTARDSC / SS7020 at a heating rate of 10°C / min under a nitrogen atmosphere, and is the temperature derivative of the DSC.

[0104] The glass transition temperature (Tg) of copolymer (A) is preferably -30°C or higher, more preferably -10°C or higher, and even more preferably 0°C or higher. This is because the cycle characteristics of non-aqueous secondary batteries containing the electrode binder of the present invention are improved.

[0105] The glass transition temperature (Tg) of copolymer (A) is preferably below 100°C, more preferably below 50°C, and even more preferably below 30°C. This is because the electrode active material layer containing the electrode adhesive of the present invention improves the adhesion to the current collector foil.

[0106] [1-1-7. Synthesis method of copolymer (A)]

[0107] The copolymer (A) is obtained by copolymerizing monomers containing monomers (a1) and (a2). As monomers, internal crosslinking agents (a3) ​​and other monomers (a4) may also be copolymerized as needed. Here, the monomers used in the synthesis of copolymer (A) are sometimes collectively referred to as monomers (a). Examples of polymerization methods include, for example, emulsion polymerization of monomers (a) in an aqueous medium (b). Other components used in the synthesis of copolymer (A) using emulsion polymerization include, for example, non-polymerizable surfactants (c), basic substances (d), free radical polymerization initiators (e), chain transfer agents (f), etc. Hereinafter, these components required for the synthesis of copolymer (A), or those that can be used as needed, and the emulsion polymerization method will be described, but regarding monomers (a), as described above, they will not be described below.

[0108] The aqueous medium (b) is water, a hydrophilic solvent, or a mixture thereof. Examples of hydrophilic solvents include methanol, ethanol, isopropanol, and N-methylpyrrolidone. From the viewpoint of polymerization stability, water is preferred as the aqueous medium (b). Alternatively, a substance in which a hydrophilic solvent has been added to water can be used as the aqueous medium (b), provided that polymerization stability is not compromised.

[0109] In the emulsion polymerization of monomer (a), a surfactant (c) that is non-polymerizable and does not conform to the copolymer (B) described later can be used. Surfactant (c) can improve the dispersion stability of the dispersion (emulsion) during polymerization and / or after polymerization. Anionic surfactants and nonionic surfactants are preferred as surfactant (c).

[0110] Examples of anionic surfactants include alkylbenzene sulfonates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, and fatty acid salts.

[0111] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polycyclic phenyl ethers, polyoxyethylene alkylene alkyl ethers, sorbitol fatty acid esters, and polyoxyethylene sorbitol fatty acid esters.

[0112] The surfactants mentioned above can be used alone or in combination of two or more.

[0113] When monomer (a) is emulsion polymerized in an aqueous medium (b), an alkaline substance (d) can be added. By adding the alkaline substance (d), the acidic components contained in monomer (a) can be neutralized, and the pH can be adjusted. By adjusting the pH, the mechanical and chemical stability of the dispersion after emulsion polymerization can be improved.

[0114] The pH of the dispersion at 23°C can be adjusted appropriately by means of the electrode specifications and the conditions for preparing the slurry (described later), and is not limited, but is preferably 1.5 to 10, more preferably 6.0 to 9.0, and even more preferably 5.0 to 9.0. This is because it inhibits the sedimentation of active substances in the electrode slurry (described later).

[0115] Examples of alkaline substances (d) include ammonia, triethylamine, sodium hydroxide, and lithium hydroxide. These alkaline substances (d) can be used alone or in combination of two or more.

[0116] The free radical polymerization initiator (e) used in emulsion polymerization is not particularly limited and can be a known substance. Examples of free radical polymerization initiators include persulfates such as ammonium persulfate and potassium persulfate; hydrogen peroxide; azo compounds; and organic peroxides such as tert-butyl hydroperoxide, tert-butyl peroxybenzoate, and isopropylbenzene hydroperoxide. Persulfates and organic peroxides are preferred. In this embodiment, the free radical polymerization initiator can be used in conjunction with a reducing agent such as sodium bisulfite, Rongalite, or ascorbic acid during emulsion polymerization to perform redox polymerization.

[0117] The amount of free radical polymerization initiator added relative to 100 parts by mass of monomer (a) is preferably 0.10 parts by mass or more, more preferably 0.80 parts by mass or more. This is because it can improve the conversion rate of monomer (a) to copolymer (A) during polymerization. The amount of free radical polymerization initiator added relative to 100 parts by mass of monomer (a) is preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less. This is because it can increase the molecular weight of copolymer (A) and reduce the swelling rate of the electrode active material layer in the electrolyte.

[0118] Chain transfer agents (f) are used in emulsion polymerization to adjust the molecular weight of the copolymer (A). Examples of chain transfer agents (f) include n-dodecyl mercaptan, tert-dodecyl mercaptan, n-butyl mercaptan, 2-ethylhexyl mercaptoacetate, 2-mercaptoethanol, β-mercaptopropionic acid, methanol, n-propanol, isopropanol, tert-butanol, benzyl alcohol, etc.

[0119] Examples of emulsion polymerization methods include those that continuously supply the components used in emulsion polymerization while performing the polymerization. The temperature for emulsion polymerization is not particularly limited, but is, for example, 30–90°C, preferably 50–85°C, and more preferably 55–80°C. Emulsion polymerization is preferably carried out while stirring. Furthermore, the monomer (a) and the free radical polymerization initiator are preferably continuously supplied in a homogeneous manner within the reaction vessel.

[0120] [1-2. Copolymer (B)]

[0121] [1-2-1. Structural units contained in copolymer (B)]

[0122] The copolymer (B) has a 21st structural unit as shown in formula (1), a 22nd structural unit as shown in formula (2), and a 23rd structural unit as shown in formula (3). The copolymer (B) preferably has a plurality of olefinically unsaturated bonds in one molecule. The copolymer (B) may contain structural units that do not conform to any of the 21st, 22nd, and 23rd structural units.

[0123] Furthermore, in copolymer (B), when describing the composition of structural units, terminal structures are not considered unless otherwise specified. For example, the content of a certain structural unit in copolymer (B) is, unless otherwise specified, the content of that structural unit in the structure excluding the terminal structure. In addition, if copolymer (B) is considered to be composed of a certain structural unit, it may include terminal structures in addition to that structural unit. Here, the so-called terminal structure in copolymer (B) is a structure located on the molecular end side compared to the ether bond closest to the molecular end, and is not included in any of the structures in formulas (1) to (3) below. Furthermore, the terminal structure does not include the structures shown in formulas (1) to (3) below.

[0124]

[0125] In equation (2), R 1 It can be an alkyl group having 1 or more but less than 6 carbon atoms and branching. R 1 Preferably, it has 4 or fewer carbon atoms, more preferably 2 or fewer carbon atoms, and even more preferably methyl.

[0126]

[0127] In equation (3), R 2 It is a group containing an olefinic unsaturated bond. R 2Preferably, it has at least one selected from vinyloxy (-OCH2=CH2), allyloxy (-OCH2-CH2=CH2), (meth)acryloyl, (meth)acryloyloxy, and -OCH2-CH2-CH2=CH2; more preferably, it has at least one selected from allyloxy, (meth)acryloyl, and (meth)acryloyloxy; and even more preferably, it has allyloxy. Each 23rd structural unit preferably contains one olefinic unsaturated bond.

[0128] R 2 The preferred structure is represented by the following formula (4).

[0129] -R 21 -R 22 (4)

[0130] In equation (4), R 21 R can be an alkylene group having 1 to 5 carbon atoms and branched chains. 22 It is any one of vinyloxy, allyloxy, (meth)acryloyl, (meth)acryloyloxy, and -OCH2-CH2-CH2=CH2.

[0131] In equation (4), R 21 Preferably, it is an alkylene group having 1 or 2 carbon atoms, more preferably a methylene group. In formula (4), R 22 More preferably, it is any one of allyloxy, (meth)acryloyl, and (meth)acryloyloxy, and even more preferably, allyloxy.

[0132] [1-2-2. Content of each structural unit in copolymer (B)]

[0133] By adjusting the content of structural units 21 and 22 in copolymer (B), the hydrophilicity of copolymer (B) can be controlled within an appropriate range. For example, increasing the content of structural unit 21 in copolymer (B) increases the hydrophilicity of copolymer (B), while decreasing the content of structural unit 21 decreases the hydrophilicity of copolymer (B).

[0134] By adjusting the content of structural units 21 and 22 in copolymer (B), the crystallinity of copolymer (B) can be adjusted to an appropriate range, thus controlling the crystallinity of copolymer (B). For example, increasing the content of structural unit 21 in copolymer (B) increases the crystallinity of copolymer (B), while decreasing the content of structural unit 21 decreases the crystallinity of copolymer (B).

[0135] The following explains the relationship between the contents of these structural units contained in copolymer (B).

[0136] In copolymer (B), the content of the 21st structural unit among all structural units is 5.0 mol% or more, preferably 18 mol% or more, and more preferably 25 mol% or more. In copolymer (B), the content of the 21st structural unit among all structural units is 98 mol% or less, preferably 97 mol% or less.

[0137] In copolymer (B), the content of the 22nd structural unit among all structural units is 0.30 mol% or more, preferably 0.50 mol% or more, and more preferably 0.70 mol% or more. In copolymer (B), the content of the 22nd structural unit among all structural units is 90 mol% or less, preferably 80 mol% or less, and more preferably 75 mol% or less.

[0138] In copolymer (B), the content of the 23rd structural unit among all structural units is 0.30 mol% or more, preferably 0.50 mol% or more, and more preferably 0.70 mol% or more. In copolymer (B), the content of the 23rd structural unit among all structural units is 10 mol% or less, preferably 6.0 mol% or less, and more preferably 4.5 mol% or less.

[0139] The total content of structural units 21, 22 and 23 of all structural units of copolymer (B) is 90% by mass or more, preferably 95% by mass or more, more preferably 98% by mass or more, and most preferably 100% by mass.

[0140] Furthermore, the structural units constituting copolymer (B) do not include end structures (as defined above). The same applies to copolymer (B1) according to the first embodiment described below, and copolymer (B2) according to the second embodiment.

[0141] [1-2-3. Copolymer (B) approach]

[0142] As copolymer (B), two preferred embodiments with different hydrophilicities are given below. These embodiments will be described as copolymer (B1) according to the first embodiment and copolymer (B2) according to the second embodiment. Copolymer (B2) according to the second embodiment has higher hydrophilicity than copolymer (B1) according to the first embodiment.

[0143] [1-2-4. Copolymer (B1) (Type 1)]

[0144] In the copolymer (B1), the content of the 21st structural unit among all structural units is preferably 5.0 mol% or more, more preferably 18 mol% or more, and even more preferably 25 mol% or more. In the copolymer (B1), the content of the 21st structural unit among all structural units is preferably 50 mol% or less, more preferably 40 mol% or less.

[0145] In the copolymer (B1), the content of the 22nd structural unit among all structural units is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more. In the copolymer (B1), the content of the 22nd structural unit among all structural units is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 75 mol% or less.

[0146] In the copolymer (B1), the content of the 23rd structural unit among all structural units is preferably 0.30 mol% or more, more preferably 0.50 mol% or more, and even more preferably 0.70 mol% or more. In the copolymer (B1), the content of the 23rd structural unit among all structural units is preferably 10 mol% or less, more preferably 6.0 mol% or less, and even more preferably 4.5 mol% or less.

[0147] [1-2-5. Copolymer (B2) (Second Method)]

[0148] In the copolymer (B2), the content of the 21st structural unit among all structural units is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more. In the copolymer (B2), the content of the 21st structural unit among all structural units is preferably 98 mol% or less, more preferably 97 mol% or less.

[0149] In the copolymer (B2), the content of the 22nd structural unit among all structural units is preferably 0.30 mol% or more, more preferably 0.50 mol% or more, and even more preferably 0.70 mol% or more. In the copolymer (B2), the content of the 22nd structural unit among all structural units is preferably 20 mol% or less, more preferably 15 mol% or less, and even more preferably 10 mol% or less.

[0150] In the copolymer (B2), the content of the 23rd structural unit among all structural units is preferably 0.30 mol% or more, more preferably 0.50 mol% or more, and even more preferably 0.70 mol% or more. In the copolymer (B2), the content of the 23rd structural unit among all structural units is preferably 10 mol% or less, more preferably 6.0 mol% or less, and even more preferably 4.5 mol% or less.

[0151] [1-2-6. Structure of copolymer (B)]

[0152] The copolymer (B) is preferably a block copolymer having a first block comprising a 21st structural unit, a second block comprising a 22nd structural unit, and a third block comprising a 23rd structural unit. More preferably, the copolymer (B) is a ternary block copolymer composed of the first, second, and third blocks (wherein, as defined above, it may include terminal structures). The copolymer (B) is even more preferably a ternary block copolymer obtained by sequentially arranging the first, second, and third blocks (i.e., a second block exists between the first and third blocks).

[0153] The preferred range of the weight-average molecular weight of copolymer (B) varies depending on the presence or absence of water solubility of copolymer (B). When an aqueous solution containing 0.1% by mass of copolymer (B) can be prepared by dissolving copolymer (B) in a 0.1M NaNO3 aqueous solution, the weight-average molecular weight of copolymer (B) is the pullulan equivalent value determined by aqueous GPC under the conditions shown below.

[0154] (Water System GPC)

[0155] GPC device: GPC-101 (manufactured by Showa Denko Co., Ltd.)

[0156] Solvent: 0.1M NaNO3 aqueous solution

[0157] Sample column: Shodex Column Ohpak SB-806HQ (8.0mm I.D x 300mm) × 2; Reference column: Shodex Column Ohpak SB-800RL (8.0mm I.D x 300mm) × 2; Column temperature: 40℃

[0158] Sample concentration: 0.1% by mass

[0159] Detector: RI-71S (manufactured by Shimadzu Corporation)

[0160] Flow rate: 1 ml / min

[0161] Molecular weight standard: pullulan (P-5, P-10, P-20, P-50, P-100, P-200, P-400, P-800, P-1300, P-2500 (manufactured by Showa Denko Co., Ltd.))

[0162] In this case, the weight-average molecular weight M of copolymer (B) wThe pullulan conversion value is preferably 10,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more. This is because the electrode strength is improved. Furthermore, in this case, the weight-average molecular weight M of the copolymer (B) is... w The pullulan conversion value is preferably 300,000 or less, more preferably 200,000 or less, and even more preferably 120,000 or less. This is because the dispersibility of the solid components in the electrode slurry described later is improved.

[0163] In the case where copolymer (B) cannot be dissolved in a 0.1 M NaNO3 aqueous solution to prepare an aqueous solution containing 0.1% by mass of copolymer (B), the weight-average molecular weight of copolymer (B) is the polystyrene equivalent value determined by GPC in a solvent system under the conditions shown below.

[0164] (Solvent-based GPC)

[0165] GPC device: Waters GPC System e2695

[0166] Solvent: Tetrahydrofuran

[0167] Column: SHODEX KF-806L×2, SHODEX KF-G (manufactured by Showa Denko Co., Ltd.) Column temperature: 40℃

[0168] Column temperature: 40℃

[0169] Sample concentration: 0.2% by mass

[0170] Detector: Waters 2414RI

[0171] Flow rate: 0.65 mL / min

[0172] Molecular weight standard: Polystyrene (Shodex Polystyrene STANDARD SL-105, SM-105 (manufactured by Showa Denko Corporation))

[0173] In this case, the weight-average molecular weight M of copolymer (B) w The polystyrene equivalent value is preferably 10,000 or more, more preferably 20,000 or more, and even more preferably 30,000 or more. This is because the strength of the electrode is improved. Furthermore, in this case, the weight-average molecular weight M of the copolymer (B) is... w The polystyrene conversion value is preferably 200,000 or less, more preferably 150,000 or less, and even more preferably 80,000 or less. This is because the dispersibility of the solid components in the electrode slurry, as described later, is improved.

[0174] [1-2-7. Specific examples of copolymer (B)]

[0175] The copolymer (B) is preferably a ternary block copolymer, for example, as shown in formula (5).

[0176]

[0177] In formula (5), the preferred values ​​are n:m:l = 5.0–98: 0.30–90: 0.30–4.5, n:m:l = 18–97: 0.50–80: 0.50–6.0, and more preferably n:m:l = 25–97: 0.70–75: 0.80–4.5. The preferred ranges for the weight-average molecular weight are as described above.

[0178] The copolymer shown in formula (5) above has a first aspect ratio of n:m:l = 5.0–50:40–90:0.30–4.5, preferably n:m:l = 18–40:50–80:0.50–6, and more preferably n:m:l = 25–40:60–75:0.80–4.5. When preparing an aqueous solution containing 0.1% by mass of the copolymer involved in the first aspect, which cannot be dissolved in 0.1 M NaNO3 aqueous solution, the weight-average molecular weight converted to polystyrene is 10,000–200,000, preferably 20,000–150,000, and more preferably 30,000–80,000.

[0179] Regarding the first method, as a more specific copolymer, the copolymer (B2-1) with n:m:l = 30:69:1.0 and Mw = 50000 in formula (5) can be cited as an example.

[0180] The copolymer shown in formula (5) above has a second aspect ratio of n:m:l = 70-98:0.30-20:0.30-10, preferably n:m:l = 80-97:0.50-15:0.50-6.0, more preferably n:m:l = 90-97:0.70-10:0.80-4.5, and Mw = 50000-80000. When an aqueous solution containing 0.1% by mass of the copolymer involved in the second aspect is prepared by dissolving it in a 0.1M NaNO3 aqueous solution, the weight-average molecular weight converted to pullulan is 10000-300000, preferably 30000-200000, more preferably 50000-120000.

[0181] Regarding the second approach, as more specific polymers, examples include copolymers (B2-2) with n:m:l = 93:6.0:1.0 and Mw = 80,000 in formula (5), and copolymers (B2-3) with n:m:l = 96:1.0:3.0 and Mw = 80,000.

[0182] [1-2-8. Synthesis method of copolymer (B)]

[0183] The synthesis method of copolymer (B) is not particularly limited; for example, it can be obtained by ring-opening polymerization of an epoxide using an acid catalyst. Furthermore, trialkylaluminum, hydroxides, alkali metal alkoxides, etc., can be used as catalysts. When copolymer (B) is a block copolymer, it is preferable to polymerize the monomers corresponding to each structural unit sequentially, one by one. In this case, the order of polymerization preferably corresponds to the desired arrangement. Polymerization is preferably carried out in an aqueous medium. The aqueous medium that can be used is the same as that described above for aqueous medium (b), but it can also be different from the aqueous medium used in the synthesis of copolymer (A).

[0184] [1-3. Mass ratio of copolymer (A) to copolymer (B)]

[0185] In the electrode binder of the present invention, the mass ratio of copolymer (A) to copolymer (B) (polymer (A) / polymer (B)) is 50.0 / 50.0 or more, preferably 53.0 / 47.0 or more, more preferably 64.0 / 36.0 or more, and even more preferably 77.0 / 23.0 or more. This is because the peel strength of the electrode active material layer containing the electrode binder of the present invention to the current collector is improved. Furthermore, the cycle characteristics of non-aqueous secondary batteries with this electrode active material layer are improved.

[0186] In the electrode binder of the present invention, the mass ratio of copolymer (A) to copolymer (B) (polymer (A) / polymer (B)) is 99.0 / 1.0 or less, preferably 97.5 / 2.5 or less, more preferably 96.5 / 3.5 or less, and even more preferably 93.0 / 7.0 or less. This is because the internal resistance of a non-aqueous secondary battery having an electrode active material layer comprising the electrode binder of the present invention is reduced, and the cycle characteristics of the non-aqueous secondary battery are improved. Furthermore, when the internal resistance of the non-aqueous secondary battery is further reduced, the above-mentioned mass ratio is further preferably 88.0 / 12.0 or less.

[0187] <2. Non-aqueous secondary battery electrode binder composition>

[0188] The non-aqueous secondary battery electrode adhesive composition of this embodiment (hereinafter, sometimes referred to as adhesive composition) contains an electrode adhesive comprising copolymer (A) and copolymer (B), and an aqueous medium (C). The non-aqueous secondary battery electrode adhesive composition of this embodiment is an adhesive composition for non-aqueous secondary battery electrodes according to this embodiment. In the adhesive composition, copolymer (A) is preferably dispersed in the aqueous medium (C). Copolymer (B) can be dispersed in the aqueous medium (C) or dissolved. In addition to these components, the adhesive composition may also contain, for example, components used in the manufacture of the electrode adhesive of this invention, adhesives other than the electrode adhesive of this invention, polymers that do not conform to either copolymer (A) or copolymer (B), surfactants, etc.

[0189] Regarding the aqueous medium (C), it is the same as the aqueous medium (b) described above, but it may also be different from the aqueous medium used in the synthesis of copolymer (A) and the aqueous medium used in the synthesis of copolymer (B).

[0190] The content of the electrode adhesive of the present invention in the non-volatile components of the adhesive composition is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, and even more preferably 98% by mass or more. This is because it increases the contribution to the effect brought about by the electrode adhesive as the object of the present invention.

[0191] The concentration of the non-volatile component in the adhesive composition is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 30% by mass or more. This is because it increases the amount of the active ingredient contained in the adhesive composition. The concentration of the non-volatile component in the adhesive composition can be adjusted by the amount of the aqueous medium (C).

[0192] The concentration of non-volatile components in the adhesive composition is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. This is because it suppresses the increase in viscosity of the adhesive composition and facilitates the preparation of the slurry described later.

[0193] As an example of a method for manufacturing an adhesive composition, one method involves mixing a mixture containing copolymer (A) with a mixture containing copolymer (B), and adding other components as needed. Another example of a method for manufacturing an adhesive composition involves adding one of copolymer (A) and copolymer (B) as a mixture and the other as a solid such as powder, and adding other components as needed. Yet another example of a method for manufacturing an adhesive composition involves mixing copolymer (A) and copolymer (B) as solids, adding them to an aqueous medium (C), and adding other components as needed. However, the methods for manufacturing an adhesive composition are not limited to the examples given here.

[0194] <3. Non-aqueous secondary battery electrode slurry>

[0195] Next, a detailed description will be given of non-aqueous secondary battery electrode slurries (hereinafter sometimes referred to as "electrode slurries"). Non-aqueous secondary battery electrode slurries are slurries for use in non-aqueous secondary battery electrodes. The electrode slurry comprises the electrode binder, electrode active material, and aqueous medium as described in this invention. In the electrode slurry, copolymer (A) is preferably dispersed in an aqueous medium. Copolymer (B) can be dispersed or dissolved in an aqueous medium. In addition to these components, the electrode slurry may also contain thickeners, conductive additives, components used in the manufacture of the electrode binder as described in this invention, binders other than the electrode binder as described in this invention, polymers that do not conform to either copolymer (A) or copolymer (B), surfactants, etc.

[0196] [3-1. Content of electrode binder]

[0197] The content of the electrode binder relative to 100 parts by weight of the electrode active material is preferably 0.50 parts by weight or more, more preferably 1.0 parts by weight or more. This is because it allows the effects brought about by the electrode binder to be fully expressed.

[0198] The content of the electrode binder relative to 100 parts by weight of the electrode active material is preferably 5.0 parts by weight or less, more preferably 4.0 parts by weight or less, and even more preferably 3.0 parts by weight or less. This is because it increases the content of the electrode active material in the electrode active material layer formed using the electrode slurry.

[0199] [3-2. Electrode Active Materials]

[0200] The electrode active material is a material capable of intercarrying / deintercalating lithium ions and other ions to become charge carriers. The ions that become charge carriers are preferably alkali metal ions, more preferably lithium ions, sodium ions, or potassium ions, and even more preferably lithium ions.

[0201] When the electrode is a negative electrode, the electrode active material, i.e., the negative electrode active material, preferably comprises at least one of a carbon material, a silicon material, or a titanium material. Examples of carbon materials used as electrode active materials include, for example, coke such as petroleum coke, pitch coke, and coal coke; carbides of organic polymers; artificial graphite; and natural graphite. Examples of silicon-containing materials include, for example, elemental silicon and silicon compounds such as silicon oxide. Examples of titanium-containing materials include, for example, lithium titanate. These materials can be used alone, or in mixtures or composites.

[0202] The negative electrode active material preferably comprises at least one of carbon materials and silicon materials, and more preferably comprises carbon materials. This is because it greatly improves the adhesion between the electrode active materials and between the electrode active materials and the current collector, which is provided by the electrode binder.

[0203] When the electrode is the positive electrode, the electrode active material, i.e., the positive electrode active material, is a substance with a higher standard electrode potential compared to the negative electrode active material. Examples of positive electrode active materials include nickel-containing lithium composite oxides such as Ni-Co-Mn, Ni-Mn-Al, and Ni-Co-Al; lithium cobalt oxide (LiCoO2); spinel-type lithium manganese oxide (LiMn2O4); olivine-type lithium iron phosphate; and chalcogenide compounds such as TiS2, MnO2, MoO3, and V2O5. One of these substances can be used as the positive electrode active material, or two or more can be used in combination.

[0204] [3-3. Thickener]

[0205] Examples of thickeners include carboxymethyl cellulose (CMC), hydroxyethyl cellulose, hydroxypropyl cellulose, and other cellulose-based materials, ammonium salts of cellulose, alkali metal salts of cellulose, polyvinyl alcohol, and polyvinylpyrrolidone. The thickener preferably contains at least one of carboxymethyl cellulose, an ammonium salt of carboxymethyl cellulose, or an alkali metal salt of carboxymethyl cellulose. This is because the electrode active material is easily dispersed in the electrode slurry.

[0206] The content of thickener in the electrode slurry is preferably 0.50 parts by mass or more, and more preferably 0.80 parts by mass or more, relative to 100 parts by mass of the electrode active material. This is because the use of the electrode slurry improves the adhesion between the electrode active materials and between the electrode active material and the current collector in the electrode active material layer.

[0207] The content of thickener in the electrode slurry is preferably 3.0 parts by mass or less, more preferably 2.0 parts by mass or less, and even more preferably 1.5 parts by mass or less, relative to 100 parts by mass of the electrode active material. This is because it improves the coatability of the electrode slurry.

[0208] [3-4. Aqueous media]

[0209] Regarding the aqueous medium, it is the same as the aqueous medium (b) described above, but it may also be different from the aqueous medium used in the synthesis of copolymer (A) and the aqueous medium used in the synthesis of copolymer (B).

[0210] [3-5. Conductive additives]

[0211] Carbon black and carbon fibers are preferred as conductive additives. Examples of carbon black include furnace black, acetylene black, Denka Black (registered trademark, manufactured by Denka Corporation), and Kecchan Black (registered trademark, manufactured by Kecchan Black Industrial Co., Ltd.). Examples of carbon fibers include carbon nanotubes and carbon nanofibers. A preferred example of carbon nanotubes is VGCF (registered trademark, manufactured by Showa Denko Corporation), a type of vapor-grown carbon fiber.

[0212] [3-6. Properties of Electrode Paste]

[0213] The concentration of non-volatile components in the electrode slurry is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. This is because a higher concentration of the active components in the electrode slurry allows for the formation of a sufficient amount of electrode active material layer with a smaller amount of electrode slurry. The concentration of non-volatile components in the electrode slurry can be adjusted by the amount of aqueous medium in the electrode slurry.

[0214] The concentration of non-volatile components in the electrode paste is preferably 85% by mass or less, more preferably 75% by mass or less, and even more preferably 65% ​​by mass or less. This is because it maintains the coatability of the electrode paste well.

[0215] The viscosity of the electrode paste is preferably below 20,000 mPa·s, more preferably below 10,000 mPa·s, and even more preferably below 5,000 mPa·s. This is because it improves the coating properties of the electrode paste on the current collector, thereby improving the productivity of the electrode. The viscosity of the electrode paste is significantly affected by the concentration of non-volatile components in the electrode paste and the type and amount of thickener.

[0216] The pH of the electrode slurry at 23°C can be adjusted appropriately by the electrode specifications and manufacturing conditions, and is not limited, but is preferably 2.0 to 10, more preferably 4.0 to 9.0, and even more preferably 6.0 to 9.0. This is because it improves the durability of the battery made using the electrode slurry.

[0217] [3-7. Method for manufacturing electrode paste]

[0218] Examples of methods for preparing electrode slurries include, but are not limited to, mixing a binder composition, an electrode active material, a thickener as needed, an aqueous medium as needed, a conductive additive as needed, and other components as needed. The order in which the components are added is not particularly limited, as long as it is appropriately determined. Examples of mixing methods include using mixing apparatus such as stirring, rotating, or oscillating mixers.

[0219] <4. Electrodes of Non-Aqueous Secondary Batteries>

[0220] The non-aqueous secondary battery electrode (hereinafter, sometimes referred to as "electrode") according to this embodiment includes a current collector and an electrode active material layer formed on the current collector. Examples of electrode shapes include, for example, laminated bodies and wound bodies, but there are no particular limitations. Furthermore, the formation area of ​​the electrode active material layer on the current collector is not particularly limited; it can be formed on the entire surface of the current collector or on a portion of the surface. When the current collector is in the shape of a plate, foil, or the like, the electrode active material layer can be formed on both surfaces of the current collector or only on one surface.

[0221] [4-1. Current collector]

[0222] The current collector is preferably a metal sheet with a thickness of 0.001 mm or more and 0.5 mm or less. Examples of metals include iron, copper, aluminum, nickel, and stainless steel. When the electrode of the non-aqueous secondary battery is the negative electrode of a lithium-ion secondary battery, the current collector is preferably copper foil.

[0223] [4-2. Electrode active material layer]

[0224] The electrode active material layer involved in this embodiment includes an electrode binder and an electrode active material. The electrode active material layer may include conductive additives, thickeners, etc. The components mentioned herein are as described above.

[0225] [4-3. Electrode Manufacturing Method]

[0226] As a method of manufacturing electrodes, for example, electrodes can be manufactured by coating an electrode slurry onto a current collector, drying it to form an electrode active material layer, and then cutting it into appropriate sizes.

[0227] There are no particular limitations on the method for coating electrode paste onto the current collector, and examples include, for instance, the reverse roller method, the direct roller method, the doctor blade method, the knife method, the extrusion method, the curtain method, the gravure method, the rod method, the impregnation method, and the extrusion method. Among these, considering the viscosity and drying properties of the electrode paste, the doctor blade method, the knife method, or the extrusion method are preferred because they can produce an electrode active material layer with a smooth surface and minimal thickness variation.

[0228] The electrode paste can be applied to only one side of the current collector or to both sides. When applying the electrode paste to both sides of the current collector, it can be applied sequentially, one side at a time, or both sides can be applied simultaneously. Furthermore, the electrode paste can be applied to the current collector continuously or intermittently. The coating amount of the electrode paste can be appropriately determined based on the battery's design capacity and the composition of the electrode paste. Although the coating amount of the electrode paste is related to its properties, 13 mg / cm³ is preferred. 2The following (coating amount on each side when coated on both sides) is because it can suppress the formation of cracks on the electrode surface during the drying process of the electrode paste.

[0229] An electrode active material layer is formed on the current collector by drying the electrode paste coated on it. The drying method for the electrode paste is not particularly limited and can be used alone or in combination, such as hot air, reduced pressure or vacuum environment, (far)infrared radiation, or low-temperature air. The drying temperature and drying time of the electrode paste can be appropriately adjusted according to the concentration of non-volatile components in the electrode paste and the amount of coating applied to the current collector. The drying temperature is preferably 40°C or higher and 350°C or lower, and from a production point of view, 60°C or higher and 100°C or lower is more preferred. The drying time is preferably 1 minute or more and 30 minutes or less.

[0230] The electrode sheet, on which an electrode active material layer is formed on the current collector, can be cut to the appropriate size and shape for use as an electrode. There are no particular limitations on the cutting method for the electrode sheet; for example, slit cutting, laser cutting, wire cutting, a cutting machine, Thomson cutting, etc., can be used.

[0231] Before or after cutting the electrode sheet, it can be pressed as needed. This allows the electrode active material to be firmly bonded through the current collector, further enabling the miniaturization of non-aqueous batteries due to the thinner electrode. As a pressing method, general methods can be used, but die pressing or roller pressing is particularly preferred. In the case of die pressing, the pressing pressure is not particularly limited, but 0.5 t / cm is preferred. 2 Above and 5t / cm 2 In the case of the roller pressing method, the linear pressure is not particularly limited, but it is preferably 0.5 t / cm or higher and 5 t / cm or lower. This is because, while obtaining the aforementioned effects brought about by pressing, it suppresses the reduction in the insertion and desorption capacity of charge carriers such as lithium ions into the electrode active material.

[0232] <5. Non-aqueous secondary batteries>

[0233] As a preferred example of the non-aqueous secondary battery according to this embodiment, a lithium-ion secondary battery will be described, but the battery configuration is not limited to that described herein. The non-aqueous secondary battery according to this embodiment houses components such as a positive electrode, a negative electrode, an electrolyte, and a separator as needed within an outer casing. One or both of the positive and negative electrodes use electrodes manufactured by the above-described method. In the non-aqueous secondary battery according to this embodiment, at least one of the positive and negative electrodes contains the electrode adhesive of the present invention, but preferably at least the negative electrode contains the electrode adhesive of the present invention.

[0234] [5-1. Electrolyte]

[0235] As the electrolyte, a non-aqueous liquid with ion conductivity is used. Examples of electrolytes include solutions that dissolve the electrolyte in organic solvents and ionic liquids, but the former is preferred. This is because it results in lower manufacturing costs and a non-aqueous battery with low internal resistance.

[0236] Alkali metal salts can be used as electrolytes, and the appropriate choice can be made based on the type of electrode active material. Examples of suitable electrolytes include LiClO4, LiBF6, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, and LiB2. 10 Cl 10 Examples of alkali metal salts include LiAlCl4, LiCl, LiBr, LiB(C2H5)4, CF3SO3Li, CH3SO3Li, LiCF3SO3, LiC4F9SO3, Li(CF3SO2)2N, and aliphatic lithium carboxylate. Other alkali metal salts can also be used as electrolytes.

[0237] Organic solvents used to dissolve electrolytes are not particularly limited, but can include, for example, carbonate compounds such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), dimethyl carbonate (DMC), fluoroethylene carbonate (FEC), and ethylene carbonate (VC); and nitrile compounds such as acetonitrile.

[0238] Carboxylic acid esters such as ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate. These organic solvents can be used individually or in combination of two or more. Preferably, substances that combine linear carbonate solvents are used. Examples of linear carbonate solvents include diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate.

[0239] [5-2. Exterior body]

[0240] As the outer casing, materials such as laminated aluminum foil and resin film can be used, but are not limited to these. The battery can be any shape, such as coin-shaped, button-shaped, sheet-shaped, cylindrical, square, or flat.

[0241] Example

[0242] In the following embodiments, as examples of the structure of the present invention, a negative electrode for a lithium-ion secondary battery and a lithium-ion secondary battery were manufactured. The effects of the present invention were confirmed compared with the negative electrode and lithium-ion secondary battery involved in the comparative examples. However, the present invention is not limited to these examples. Furthermore, unless otherwise specified, the water used in the following embodiments and comparative examples is ion-exchanged water.

[0243] <1. Aqueous dispersion of copolymer (A) or copolymer (CA)>

[0244] [1-1. Preparation of an aqueous dispersion of copolymer (A) or copolymer (CA)]

[0245] The monomers (a) with the compositions (parts by mass) shown in Tables 1 and 2 were subjected to free radical polymerization to obtain aqueous dispersions of copolymers (A-1) to (A-9) and copolymers (CA-1) to (CA-3). Here, copolymers (A-1) to (A-9) are referred to as copolymer (A) without distinguishing between them, and copolymers (CA-1) to (CA-3) are referred to as copolymer (CA) without distinguishing between them. The content of copolymer (A) or copolymer (CA) in the aqueous dispersion was set to 40% by mass. Polyoxyethylene alkyl ether sulfate salt (manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., Hytenol 08E) was used as a surfactant during polymerization. In the resulting aqueous dispersion, the above surfactant contained 0.20 parts by mass per 100 parts by mass of copolymer (A) or copolymer (CA).

[0246] [1-2. Evaluation 1: Determination of the glass transition temperature of copolymer (A) and copolymer (CA)]

[0247] The determination of the glass transition temperatures of copolymers (A) and (CA) is explained. The aqueous dispersions of the obtained copolymers (A) and (CA) were cast onto a polyethylene sheet, dried at 50°C for 5 hours, and then vacuum-dried at 50°C for 1 hour under 98 kPa to obtain a film with a thickness of 0.5 mm.

[0248] The obtained film was cut into 2mm × 2mm pieces, sealed in an aluminum disk, and DSC measurements were performed using a Hitachi High-Tech Chemicals EXSTAR DSC / SS7020 at a heating rate of 10°C / min under a nitrogen atmosphere. The peak temperature of the DDSC plot obtained as the temperature derivative of the DSC was measured and set as the glass transition temperature Tg (°C) of the copolymer (P) and copolymer (CP). The measurement temperature range was set to -40°C to 200°C. The measured glass transition temperatures are shown in Table 1.

[0249]

[0250] Table 2

[0251]

[0252] ※1: The value in the right column of monomer (a) is the number of parts by mass of each monomer when the total amount of monomer (a1) is set to 100 parts by mass.

[0253] <2. Preparation of aqueous solutions or dispersions of copolymer (B)>

[0254] Three ternary block copolymers, comprising 40% by mass of aqueous dispersions and aqueous solutions, were prepared, each consisting of a block composed of structural unit (10), a block composed of structural unit (11), and a block composed of structural unit (12) arranged sequentially. The content of each structural unit in the ternary block copolymers of these aqueous dispersions and aqueous solutions differs. The compositions of these three copolymers (B-1) to (B-3) are shown in Table 3.

[0255] Table 3

[0256] Copolymer (B) Structural unit (10) Structural unit (11) Structural unit (12) Weight-average molecular weight Mw B-1 30 mol% 69mol% 1.0 mol% 50,000 (conversion to polystyrene) B-2 93mol% 6.0 mol% 1.0 mol% 80,000 (conversion of pullulan) B-3 96mol% 1.0 mol% 3.0 mol% 80,000 (conversion of pullulan)

[0257]

[0258]

[0259] <3. Adhesive Composition>

[0260] [3-1. Preparation of adhesive composition]

[0261] The dispersions of copolymer (A) or copolymer (CA) were mixed with the dispersions or aqueous solutions of copolymer (B). Regarding the mixing amounts in the various examples and comparative examples, the ratio of copolymer (A) or copolymer (CA) to copolymer (B) was as shown in Tables 4 and 5 (for ease of comparison of different conditions, both Tables 4 and 5 are listed for Example 1) by mass.

[0262]

[0263]

[0264] The concentration (mass %) of the non-volatile components in the adhesive compositions obtained in the Examples and Comparative Examples was determined by the following methods. The results are shown in Tables 4 and 5.

[0265] [3-2. Evaluation 2: Concentration of non-volatile components in the adhesive composition]

[0266] 1 g of the adhesive composition was weighed into an aluminum dish with a diameter of 5 cm. The mixture was dried at 105 °C for 1 hour in a desiccator with air circulation. The mass of the remaining components was then determined. The mass percentage (mass%) of the remaining components after drying relative to the mass (1 g) of the adhesive composition before drying was calculated as the concentration of non-volatile components.

[0267] <4. Evaluation of Electrode and Battery Performance>

[0268] The negative electrode and lithium-ion secondary battery were fabricated using the binder compositions prepared in the various embodiments and comparative examples, and the results were evaluated.

[0269] [4-1. Battery Making]

[0270] [4-1-1. Making the Positive Electrode]

[0271] As a positive electrode active material, LiNi 0.6 Mn 0.2 Co 0.2 A positive electrode slurry is prepared by mixing 94 parts by weight of O2, 3 parts by weight of acetylene black as a conductive additive, and 3 parts by weight of poly1,1-difluoroethylene as a binder, and then adding 50 parts by weight of N-methylpyrrolidone.

[0272] Positive electrode slurry was applied to both sides of an aluminum foil (positive current collector) with a thickness of 15 μm using a direct roller coating method. The amount of positive electrode slurry applied to the positive current collector was adjusted so that the thickness after processing by the roller press was 125 μm on each side.

[0273] The positive electrode slurry coated on the positive current collector was dried at 120°C for 5 minutes, and then pressed using a roller press (made by Sunchine Corporation, press load 5t, roller width 7cm) to obtain a positive electrode sheet with a positive active material layer. The obtained positive electrode sheet was cut into 50mm×40mm pieces, and conductive connectors (tabs) were attached to produce the positive electrode.

[0274] [4-1-2. Making the negative electrode]

[0275] 100 parts by weight of artificial graphite (G49, manufactured by Jiangxi Zichen Technology Co., Ltd.) as the negative electrode active material, 3.9 parts by weight of the binder composition prepared in each example and comparative example (1.5 parts by weight as non-volatile component), and 62 parts by weight of a 2% aqueous solution of CMC (carboxymethyl cellulose sodium salt / Nippon Paper Kemical Co., Ltd. Sunroes (registered trademark) MAC500LC) were mixed, and 28 parts by weight of water were further added to obtain the negative electrode slurry.

[0276] Negative electrode paste was applied to both sides of a 10μm thick copper foil (negative electrode current collector) using a direct roller coating method. The amount of negative electrode paste applied to the negative electrode current collector was adjusted so that the thickness after processing by the roller press was 170μm on each side.

[0277] The negative electrode slurry coated on the negative current collector was dried at 90°C for 10 minutes, and then pressed using a roller press (manufactured by Sunchine Corporation, press load 8t, roller width 7cm) to obtain a negative electrode sheet with a negative electrode active material layer formed on the current collector. The obtained negative electrode sheet was cut into 52mm×42mm pieces, and conductive connectors (tabs) were attached to produce the negative electrode.

[0278] [4-1-3. Battery Making]

[0279] A separator made of a polyolefin-based porous membrane (polyethylene, 25 μm) is placed between the positive and negative electrodes, with the positive and negative active material layers facing each other, and housed in an aluminum laminated casing (battery pack). Electrolyte is injected into this casing for vacuum impregnation, and the casing is then packaged using a vacuum heat-sealing machine to produce an evaluation lithium-ion secondary battery. An electrolyte is prepared by mixing 1 part by mass of vinylene carbonate with 99 parts by mass of a solution obtained by dissolving LiPF6 at 1.0 mol / L in a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / diethyl carbonate (DEC) = 30 / 50 / 20 (volume ratio).

[0280] [4-2. Evaluation of Electrodes and Cells]

[0281] [4-2-1. Evaluation 3: Peel strength of the negative electrode active material layer (electrode performance)]

[0282] The peel strength of the negative electrode active material layer to the current collector was measured as follows. The negative electrode sheet, pressed in the aforementioned negative electrode manufacturing process, was cut into 25mm × 100mm pieces to create test pieces. The negative electrode active material layer on the test piece was bonded to a 50mm wide and 200mm long SUS board using double-sided tape (NITTOTAPE (registered trademark) No. 5, manufactured by Nitto Denko Co., Ltd.), with the center of the test piece aligned with the center of the SUS board. Furthermore, the double-sided tape was bonded to cover the entire area of ​​the test piece.

[0283] After placing the test piece against the SUS board for 10 minutes, the negative electrode active material layer adhered to the SUS board was peeled 20 mm from one end of the test piece along its length. The copper foil side of the test piece was then folded back 180°, and this portion (the copper foil side of the test piece with the negative electrode active material layer peeled off) was clamped with the upper clamp of the testing machine. Further, one end of the SUS board with the negative electrode active material layer peeled off was clamped with the lower clamp. In this state, the copper foil was peeled off from the test piece at a speed of 100 ± 10 mm / min, and a graph of peel length (mm) versus peel force (mN) was obtained. The average peel force (mN) for peel lengths of 10–45 mm was calculated from the obtained graph, and the value obtained by dividing the average peel force by the width of the test piece (25 mm) was taken as the peel strength of the negative electrode active material layer (mN / mm). Furthermore, in any of the embodiments and comparative examples, no peeling occurred between the double-sided tape and the SUS plate, or between the double-sided tape and the negative electrode active material layer, during the test.

[0284] [4-2-2. Evaluation 4: Battery Internal Resistance (DCR)]

[0285] The battery's internal resistance (DCR(Ω)) was measured at 25°C using the following steps: A constant current charge of 0.2C was applied from the quiescent potential until 3.6V was reached, bringing the state of charge (SOC) to 50% of the initial capacity. Then, the battery was discharged for 60 seconds at current values ​​of 0.2C, 0.5C, 1C, and 2C. The DCR(Ω) at SOC50% was determined by the relationship between these four current values ​​(values ​​over 1 second) and voltage.

[0286] [4-2-3. Evaluation 5: Cycle capacity retention at high temperatures (battery performance)]

[0287] The battery's high-temperature cycle capacity retention was maintained at 45°C by repeatedly performing the following steps (i) to (iv). Here, each operation in steps (i) to (iv) is considered as one cycle.

[0288] (i) Charge at a current of 1C until the voltage becomes 4.2V (constant current (CC) charging).

[0289] (ii) Charge at a voltage of 4.2V until the current becomes 0.05C (constant voltage (CV) charging).

[0290] (iii) Let stand for 30 minutes.

[0291] (iv) Discharge at a current of 1C until the voltage becomes 2.75V (constant current (CC) discharge).

[0292] The time integral value of the current in steps (i) and (ii) is set as the charging capacity, and the time integral value of the current in step (iv) is set as the discharging capacity. The discharge capacity of the first cycle and the discharge capacity of the 100th cycle were measured. The cycle capacity retention rate of the battery at high temperature was calculated as 100 × (discharge capacity of the 100th cycle) / (discharge capacity of the first cycle) [%], and is shown in Tables 1 and 2.

[0293] <5. Evaluation Results>

[0294] Observing the evaluation results of each embodiment, it can be seen that the peel strength of the negative electrode active material layer is high in the electrode involved in any embodiment. It can also be seen that in the evaluation of the battery, the battery involved in any embodiment has low internal resistance and high discharge capacity retention (excellent cycle characteristics).

[0295] In Comparative Example 1, electrodes and a battery were fabricated using a binder composition that did not contain copolymer (B). However, the internal resistance of the battery could not be sufficiently reduced, and the discharge capacity retention was also insufficient.

[0296] In Comparative Example 2, electrodes and batteries were fabricated using an excess binder composition containing copolymer (B). However, the peel strength of the negative electrode active material layer in the electrode was low. Furthermore, the discharge capacity retention of the battery was also insufficient.

[0297] In Comparative Example 3, a binder composition was prepared using a copolymer (CA-1) without a 12th structural unit. In Comparative Example 4, a binder composition was prepared using a copolymer (CA-2) with an excess of a 12th structural unit. In Comparative Example 5, a binder composition was prepared using a copolymer (CA-3) with an excess of a 13th structural unit. However, the peel strength of the negative electrode active material layer in the electrode prepared using these binder compositions was low. Furthermore, the internal resistance of the battery could not be sufficiently reduced, and the discharge capacity retention rate was also insufficient.

[0298] Based on the above, the non-aqueous secondary battery electrode adhesive of the present invention effectively improves the peel strength of the electrode active material layer to the current collector in a non-aqueous secondary battery, which can help reduce the internal resistance of the battery and improve its cycle characteristics.

Claims

1. A non-aqueous secondary battery electrode adhesive, characterized in that, It contains copolymer (A) and copolymer (B). The copolymer (A) is a polymer of a compound having olefinic unsaturated bonds. The copolymer (A) has an 11th structural unit derived from monomer (a1) and a 12th structural unit derived from monomer (a2), or has an 11th structural unit derived from monomer (a1), a 12th structural unit derived from monomer (a2), and a 13th structural unit derived from internal crosslinking agent (a3). The monomer (a1) is a nonionic compound having olefinic unsaturated bonds, lacking both hydroxyl and cyano groups, and not having multiple independent olefinic unsaturated bonds. The monomer (a2) is a compound having olefinic unsaturated bonds and anionic functional groups, but not having multiple independent olefinic unsaturated bonds. The internal crosslinking agent (a3) ​​is a compound having multiple independent olefinic unsaturated bonds and capable of forming a crosslinked structure in the free radical polymerization of monomers containing monomers (a1) and (a2). In the copolymer (A), the content of the 12th structural unit is 1.0 part by mass or more and 30 parts by mass or less relative to 100 parts by mass of the 11th structural unit. In the copolymer (A), the content of the 13th structural unit is 0 parts by mass or more and 20 parts by mass or less relative to 100 parts by mass of the 11th structural unit. The copolymer (B) has 5.0 mol% and 98 mol% of the 21st structural unit as shown in formula (1) in all structural units, 0.30 mol% and 90 mol% of the 22nd structural unit as shown in formula (2) in all structural units, and 0.30 mol% and 10 mol% of the 23rd structural unit as shown in formula (3) in all structural units. The total content of the 21st structural unit, the 22nd structural unit, and the 23rd structural unit in all structural units of the copolymer (B) is 90% by mass or more. The mass ratio of the content of copolymer (A) to the content of copolymer (B) is 50.0 / 50.0 or more and 99.0 / 1.0 or less. In formula (2), R 1 is an alkyl group having 1 or more and 6 or less carbon atoms which can have a branched chain; In formula (3), R 2 is a group having an ethylenically unsaturated bond.

2. The non-aqueous secondary battery electrode adhesive according to claim 1, wherein the copolymer (B) comprises The 21st structural unit comprises 5.0 mol% or more and 50 mol% or less. The 22nd structural unit is 40 mol% or more and 90 mol% or less. The 23rd structural unit is 0.30 mol% or more and 10 mol% or less.

3. The non-aqueous secondary battery electrode adhesive according to claim 1, wherein the copolymer (B) comprises The 21st structural unit is 70 mol% or more and 98 mol% or less. The 22nd structural unit is 0.30 mol% or more and 20 mol% or less. The 23rd structural unit is 0.30 mol% or more and 10 mol% or less.

4. The nonaqueous secondary battery electrode binder according to any one of claims 1 to 3, in the formula (3), R 2 has at least one selected from the group consisting of vinyloxy group, allyloxy group, (meth)acryloyl group, (meth)acryloyloxy group, and -OCH2-CH2-CH2=CH2.

5. The nonaqueous secondary battery electrode binder according to any one of claims 1 to 4, in the formula (3), R 2 is represented by the following formula (4), -R 21 -R 22 (4) In equation (4), R 21 R can be an alkylene group having 1 to 5 carbon atoms and branched chains. 22 It is a functional group selected from vinyloxy, allyloxy, (meth)acryloyl, and (meth)acryloyloxy.

6. The non-aqueous secondary battery electrode adhesive according to any one of claims 1 to 5, wherein the copolymer (B) is a block copolymer having a first block comprising a 21st structural unit, a second block comprising a 22nd structural unit, and a third block comprising a 23rd structural unit.

7. The non-aqueous secondary battery electrode adhesive according to any one of claims 1 to 6, wherein the monomer (a1) does not have polar functional groups.

8. The non-aqueous secondary battery electrode binder according to any one of claims 1 to 7, wherein the monomer (a2) is a compound having at least one of carboxyl and sulfonyl groups.

9. The non-aqueous secondary battery electrode adhesive according to any one of claims 1 to 8, wherein the copolymer (A) comprises a total of 80% by mass or more of the 11th structural unit and the 12th structural unit.

10. The non-aqueous secondary battery electrode adhesive according to any one of claims 1 to 9, wherein in the copolymer (A), the content of the 13th structural unit is 0.050 parts by mass or more relative to 100 parts by mass of the 11th structural unit.

11. A non-aqueous secondary battery electrode adhesive composition comprising the non-aqueous secondary battery electrode adhesive according to any one of claims 1 to 10, and an aqueous medium.

12. A non-aqueous secondary battery electrode slurry, comprising the non-aqueous secondary battery electrode binder, electrode active material, and aqueous medium as described in any one of claims 1 to 10. The aqueous medium is selected from water, hydrophilic solvents, and mixtures containing water and hydrophilic solvents.

13. A non-aqueous secondary battery electrode comprising the non-aqueous secondary battery electrode adhesive according to any one of claims 1 to 10.

14. A non-aqueous secondary battery comprising the non-aqueous secondary battery electrode of claim 13.

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