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

Abstract

The present invention aims to provide a non-aqueous secondary battery electrode adhesive, a composition thereof, and a non-aqueous secondary battery electrode that can improve the flexibility of the electrode active material layer formed on a current collector and significantly improve the discharge capacity retention rate after charge-discharge cycles. The non-aqueous secondary battery electrode adhesive of the present invention contains a copolymer (P). The copolymer (P) has: a main chain formed only by bonds between carbon atoms, substituents having amide bonds bonded to said main chain, substituents having carboxyl salts, and substituents (c) represented by the following general formula (1). The amount of amide bonds contained in each 1g of copolymer (P) is 0.050–5.0 mmol / g, the amount of substituent (b1) is 5.0–12.0 mmol / g, and the amount of substituent (c) is 0.15 × 10⁻⁶. ‑2 ~8.0×10 ‑2 mmol / g.

Description

Technical Field

[0001] This invention relates to adhesives for electrodes of non-aqueous secondary batteries, compositions thereof, electrodes for non-aqueous secondary batteries, and non-aqueous secondary batteries.

[0002] This application claims priority to Japanese Patent Application No. 2021-090167, filed on May 28, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] Secondary batteries using non-aqueous electrolytes (non-aqueous secondary batteries) are superior to those using aqueous electrolytes in terms of high voltage, miniaturization, and weight reduction. Therefore, non-aqueous secondary batteries are widely used as power sources for laptops, mobile phones, power tools, and electronic and communication devices. Furthermore, from the perspective of applicable vehicle environments, non-aqueous batteries are also being used in electric vehicles and hybrid vehicles, with a strong demand for high output, high capacity, and long lifespan. Lithium-ion secondary batteries are a representative example of non-aqueous secondary batteries.

[0004] Non-aqueous secondary batteries consist of a positive electrode with metal oxides or similar active materials, a negative electrode with carbon materials such as graphite as active materials, and a non-aqueous electrolyte solvent centered on carbonates or flame-retardant ionic liquids. Non-aqueous secondary batteries are rechargeable and discharge-promoting batteries that rely on the movement of ions between the positive and negative electrodes. Specifically, the positive electrode is obtained by coating a slurry composed of metal oxides and a binder onto the surface of a positive current collector such as aluminum foil, drying it, and then cutting it to an appropriate size. The negative electrode is obtained by coating a slurry composed of carbon materials and a binder onto the surface of a negative current collector such as copper foil, drying it, and then cutting it to an appropriate size. The binder in both the positive and negative electrodes serves to bond the active materials to each other and to the current collector, preventing the active materials from peeling off from the current collector.

[0005] As a binder, polyvinylidene fluoride (PVDF) based binders using N-methyl-2-pyrrolidone (NMP), an organic solvent, are known. However, the adhesion between the active materials and between the active materials and the current collector is poor, requiring large quantities of binder in practical applications. Therefore, non-aqueous secondary batteries suffer from low capacity. Furthermore, the use of expensive organic solvent NMP in the binder makes it difficult to control manufacturing costs.

[0006] As a solution to these problems, water-dispersible adhesives have been developed. Water-dispersible adhesives, for example, use carboxymethyl cellulose (CMC) as a thickener and water dispersions based on (meth)acrylates or styrene-butadiene rubber (SBR).

[0007] Patent Document 1 discloses an adhesive composition for lithium-ion battery secondary electrode containing (meth)acrylate compounds and polyfunctional thiols. Patent Document 2 discloses an adhesive composition for lithium-ion secondary battery silicon-based negative electrode containing acrylic acid, a tetrafunctional (meth)acrylate monomer, and acrylamide.

[0008] Patent document 3 discloses an adhesive for non-aqueous battery electrodes containing a sodium acrylate-N-vinylacetamide copolymer (copolymer ratio: sodium acrylate / N-vinylacetamide = 10 / 90 by mass).

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2014-116265

[0012] Patent Document 2: Japanese Patent Application Publication No. 2016-181422

[0013] Patent Document 3: International Publication No. 2017 / 150200 Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] However, the adhesive using polyfunctional thiols described in Patent Document 1 requires the use of carboxymethyl cellulose as a thickener, making the slurry preparation process complex. Moreover, in this adhesive, the adhesion between the active materials and between the active materials and the current collector is insufficient, and when producing electrodes with a small amount of adhesive, there is a problem that some of the active material peels off during the process of cutting the current collector.

[0016] In the adhesives using 4-functional acrylates disclosed in Patent Document 2, as shown in Comparative Example 5 described later, there is a problem that the flexibility of the electrode cannot be ensured, and cracks are generated when the electrode is wound.

[0017] In the non-aqueous battery electrode adhesive disclosed in Patent Document 3, as shown in Comparative Example 3 described later, there are problems such as low electrode flexibility and low discharge capacity retention after charge-discharge cycles.

[0018] Therefore, the present invention aims to provide a non-aqueous secondary battery electrode adhesive and a non-aqueous secondary battery electrode adhesive composition, which can improve the flexibility of the electrode active material layer formed on the current collector and can significantly improve the discharge capacity retention rate after charge-discharge cycles.

[0019] In addition, the present invention aims to provide a non-aqueous secondary battery electrode with high flexibility and high discharge capacity retention after charge-discharge cycles.

[0020] Therefore, the purpose of this invention is to provide a non-aqueous secondary battery with electrodes that are highly flexible and have a high discharge capacity retention rate after charge-discharge cycles.

[0021] Problem-solving methods

[0022] In order to solve the above problems, the present invention is described below [1] to

[14] .

[0023] [1]. A non-aqueous secondary battery electrode adhesive, comprising a copolymer (P), characterized in that the copolymer (P) has:

[0024] A main chain consisting solely of bonds between carbon atoms

[0025] Substituents containing amide bonds,

[0026] Substituents in salts containing carboxyl groups, and

[0027] The substituent (c) represented by the following general formula (1)

[0028] The substituent having an amide bond, the substituent having a carboxyl group, and the substituent (c) are respectively bonded to the main chain.

[0029] The copolymer (P) contains amide bonds in an amount of 0.050 mmol / g or more and 5.0 mmol / g or less per 1g.

[0030] The amount of carboxyl salt contained in each 1g of the copolymer (P) is more than 5.0 mmol / g and less than 12.0 mmol / g.

[0031] The amount of the substituent (c) contained in each 1g of the copolymer (P) is 0.15 × 10⁻⁶. -2 mmol / g or higher and 8.0×10 -2 Below mmol / g

[0032]

[0033] In general formula (1), R 31 For hydrocarbon groups, m and n represent the groups with respect to R. 31 The number of substituents that are directly bound, where m is an integer greater than or equal to 0, n is an integer greater than or equal to 1, and m+n≥2.

[0034] [2]. The non-aqueous secondary battery electrode adhesive as described in [1], wherein R in the general formula (1) 31 It is composed of carbon atoms and hydrogen atoms.

[0035] [3]. The non-aqueous secondary battery electrode adhesive as described in [1] or [2], wherein in the general formula (1), R31 It has multiple carbon atoms, and all the bonds between the carbon atoms are single bonds.

[0036] [4]. The non-aqueous secondary battery electrode adhesive as described in any of [1] to [3], wherein when the formula weight of the substituent (c) is set to Mc, Mc / (m+n)≤400.

[0037] [5]. The non-aqueous secondary battery electrode adhesive as described in any of [1] to [4], wherein the substituent (c) is derived from the structure of a polyfunctional thiol compound (C) having two or more thiol groups in one molecule.

[0038] [6]. The non-aqueous secondary battery electrode adhesive as described in any of [1] to [5], wherein the copolymer (P) further contains 0.50% by mass and 20.0% by mass of the structural unit (d) shown in general formula (2),

[0039]

[0040] In general formula (2), R 41 R 42 R 44 Each is independently an alkyl group having 1 or more hydrogen atoms and 5 or fewer carbon atoms, R 43 It is an alkyl group with 1 or more but less than 6 carbon atoms, R 43 The number of carbon atoms is greater than that of R 42 Many, j and k represent the number of structures connected in series within the corresponding parentheses, j is an integer greater than or equal to 1, k is an integer greater than or equal to 0, and j+k≥20.

[0041] [7]. The non-aqueous secondary battery electrode adhesive as described in any of [1] to [6], wherein the copolymer (P):

[0042] The copolymer (P) further contains 0.030 mmol / g and 1.75 mmol / g of structural unit (e) represented by the following general formula (3) per 1g.

[0043]

[0044] In general formula (3), R 51 R represents a hydrogen atom or a methyl group. 52 It is a substituent with an aromatic ring.

[0045] [8]. The non-aqueous secondary battery electrode adhesive as described in any of [1] to [7], wherein at least a portion of the amide bonds in the copolymer (P) are contained in the form of a structural unit (a) represented by the following general formula (4).

[0046]

[0047] In general formula (4), R 11 R 12 Each can be used independently to represent an alkyl group having 1 or more hydrogen atoms and 5 or fewer carbon atoms.

[0048] [9]. The non-aqueous secondary battery electrode adhesive as described in any of [1] to [8], wherein at least a portion of the salt of the carboxyl group in the copolymer (P) is contained in the form of a structural unit (b) of the following general formula (5).

[0049]

[0050] In general formula (5), R 2 This represents a hydrogen atom or a methyl group, where X is a cation.

[0051]

[10] . The non-aqueous secondary battery electrode adhesive as described in any one of [1] to [9] is characterized in that the weight-average molecular weight of the copolymer (P) is 700,000 or more and 7.5 million or less.

[0052]

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

[10] and an aqueous medium.

[0053]

[12] . A non-aqueous secondary battery electrode, comprising a current collector and an electrode active material layer formed on the surface of the current collector,

[0054] The electrode active material layer contains an adhesive and an electrode active material for a non-aqueous secondary battery electrode as described in any one of [1] to

[10] .

[0055]

[13] . A non-aqueous secondary battery, characterized in that it comprises a positive electrode, a negative electrode and an electrolyte, wherein at least one of the positive electrode and the negative electrode is the non-aqueous secondary battery electrode described in

[12] .

[0056]

[14] . A method for manufacturing a non-aqueous secondary battery electrode adhesive, characterized by a polymerization step comprising a monomer (M) having an olefinically unsaturated double bond undergoing free radical polymerization in the presence of a polyfunctional thiol compound (C) having two or more thiol groups in one molecule.

[0057] The monomer (M) contains a monomer (A) having an amide bond and a monomer (B) having a carboxyl group as a salt.

[0058] When using the monomer (M), the polyfunctional thiol compound (C), the polymerization initiator, and the chain transfer agent, if the chain transfer agent is also considered as a polymerization component, then...

[0059] The amount of monomer (A) contained in each 1g of the polymer component is 0.050 mmol / g or more and 5.0 mmol / g or less.

[0060] The amount of monomer (B) contained in each 1g of the polymeric component is 5.0 mmol / g or more and 12.0 mmol / g or less.

[0061] The amount of the polyfunctional thiol compound (C) contained in each 1g of the polymer component is 0.15 × 10⁻⁶. -2 mmol / g or higher and 8.0×10 -2 Below mmol / g.

[0062] Invention Effects

[0063] According to the present invention, a non-aqueous secondary battery electrode adhesive and a composition thereof can be provided, which can improve the flexibility of the electrode active material layer formed on the current collector and can significantly improve the discharge capacity retention rate after charge-discharge cycles.

[0064] In addition, according to the present invention, a non-aqueous secondary battery electrode with high flexibility and high discharge capacity retention after charge-discharge cycles can be provided.

[0065] Furthermore, according to the present invention, it is possible to provide a non-aqueous secondary battery with electrodes that are highly flexible and have a high discharge capacity retention rate after charge-discharge cycles. Detailed Implementation

[0066] The embodiments of the present invention will now be described in detail. In this embodiment, the battery is a secondary battery in which ions move between the positive and negative electrodes during charging and discharging. The positive electrode has a positive electrode active material, and the negative electrode has a negative electrode active material. These electrode active materials are materials capable of intercarrying and deintercalating ions. As a preferred example of a secondary battery with this structure, a lithium-ion secondary battery can be cited.

[0067] "(Meth)acrylic acid" refers to one or both of methacrylic acid and acrylic acid. "(Meth)acrylic acid monomer" refers to one or both of methacrylic acid monomer and acrylic acid monomer. "(Meth)acrylate" refers to one or both of methacrylate and acrylate.

[0068] "Weight-average molecular weight" is the pullulan conversion value calculated using gel permeation chromatography (GPC).

[0069] "Hydrocarbon group" refers to a structure consisting only of carbon and hydrogen atoms. However, this limitation does not apply in special cases, such as when some hydrogen atoms are replaced.

[0070] In the following description, if there are no atoms in front of the line representing a bond in the formula representing a structural unit, it means that the part is combined with other structural units or end structures that form the polymer.

[0071] A functional group salt refers to a salt in which a portion of the functional group's ions, after dissociation, combine with other ions besides hydrogen ions and hydroxide ions. For example, a carboxyl salt refers to a salt in which COO- combines with cations other than hydrogen ions.

[0072] <1. Non-aqueous secondary battery electrode adhesive>

[0073] The non-aqueous secondary battery electrode binder (or non-aqueous secondary battery electrode binder, hereinafter sometimes referred to as "electrode binder") of this embodiment contains the copolymer (P) described below. The electrode binder may contain other components, such as polymers other than copolymer (P), surfactants, etc.

[0074] Here, the electrode binder consists of components that do not volatilize and remain after the heating process in the battery manufacturing process described later. Specifically, the components constituting the electrode binder are the components remaining after weighing 1g of a mixture containing the electrode binder in an aluminum pan with a diameter of 5cm, drying it at 110°C for 5 hours under atmospheric pressure and air circulation in a desiccator.

[0075] The copolymer (P) content in the electrode adhesive is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more. This is because the copolymer (P) contributes more to the objective effect of the present invention.

[0076] [1-1. Copolymer (P)]

[0077] The copolymer (P) has a main chain consisting only of bonds between carbon atoms, substituents having amide bonds, substituents having carboxyl salts, and substituents (c) represented by the following general formula (1). The main chain preferably consists only of single bonds between carbon atoms.

[0078] Substituents having amide bonds, substituents having carboxyl groups, and substituent (c) are respectively bonded to the main chain. Substituents having amide bonds and substituents having carboxyl groups preferably branch off from the main chain. Substituent (c) is preferably bonded to the end of the main chain. Alternatively, multiple main chains may be bonded to one substituent (c). That is, a structure may also be formed in which multiple main chains formed by inter-carbon bonds are bonded by substituent (c) within a molecule.

[0079] The copolymer (P) preferably has at least one of the structural unit (d) shown in general formula (2) and the structural unit (e) shown in general formula (3) described later, and more preferably has both. The copolymer (P) may also have structures other than those described above, such as end structures of molecules.

[0080] The weight-average molecular weight of the copolymer (P) is preferably 700,000 or more, more preferably 1,000,000 or more, and even more preferably 1,500,000 or more. Furthermore, the weight-average molecular weight of the copolymer (P) is preferably 7,500,000 or less, more preferably 5,000,000 or less, and even more preferably 4,000,000 or less.

[0081] [1-1-1. Amide bond]

[0082] The amount of amide bonds contained in each 1g of copolymer (P) is 0.050 mmol / g or more, preferably 0.085 mmol / g or more, and more preferably 0.40 mmol / g or more. This is because it allows for the production of electrode pastes with excellent dispersibility and coatability of electrode active materials, conductive additives, etc., during the electrode paste preparation process described later. Furthermore, this is because the copolymer (P) improves the electrolyte resistance of the negative electrode active material layer.

[0083] The amount of amide bonds contained in each 1g of copolymer (P) is 5.0 mmol / g or less, preferably 3.0 mmol / g or less, more preferably 1.7 mmol / g or less, and even more preferably 0.90 mmol / g or less. This is to allow the copolymer (P) to contain other structures. Additionally, this is to suppress the formation of electrode cracks, as described later, and to improve electrode productivity.

[0084] In addition, amide bonds may also be contained together with structural units having other functional groups, such as structural unit (e) described later.

[0085] In the copolymer (P), the amide bonds are preferably contained in the form of structural units (a) represented by the following general formula (4). This is because the amide bonds are present in a relatively large amount of mass relative to the structural units (a), allowing the copolymer (P) to contain amide bonds effectively. The proportion of amide bonds contained in the structural units (a) of the copolymer (P) is preferably 95 mol% or more, more preferably 98 mol% or more, and even more preferably 99 mol% or more.

[0086]

[0087] In general formula (4), R 11 R 12 Each can be used independently to represent an alkyl group having 1 to 5 hydrogen atoms or carbon atoms.

[0088] In general formula (4), R11 R 12 More preferably, each is an alkyl group having 1 to 3 carbon atoms independently, R 11 R 12 Each and more preferably, independently, is a hydrogen atom or a methyl group.

[0089] As R 11 R 12 A particularly preferred example of the combination is R. 11 :H and R 12 :H, or R 11 :H and R 12 CH3. This is because the amount of amide bonds is relatively large relative to the mass, and the copolymer (P) can contain more amide bonds.

[0090] [1-1-2. Salts of Carboxyl Groups]

[0091] The salt of the carboxyl group is preferably a salt formed by -COO- and a monovalent cation. The monovalent cation is more preferably an alkali metal ion or an ammonium ion, even more preferably an alkali metal ion, and particularly preferably a lithium ion or a sodium ion.

[0092] The amount of carboxyl salt contained in each 1g of copolymer (P) is 5.0 mmol / g or more, preferably 6.0 mmol / g or more, and even more preferably 7.0 mmol / g or more. This is because an electrode active material layer with high peel strength to the current collector can be obtained through copolymer (P).

[0093] The amount of carboxyl salt contained in each 1g of copolymer (P) is 12.0 mmol / g or less, preferably 9.9 mmol / g or less. This is to further improve the dispersibility of solid components such as electrode active materials and conductive additives during the preparation of the electrode slurry, as described later.

[0094] Furthermore, the amount of carboxyl salt is the amount of -COO- ions that combine with cations other than hydrogen ions. For example, when two COO- ions combine with one divalent cation, there are two carboxyl salts.

[0095] In addition, carboxyl salts may also be contained together with structural units having other functional groups, such as structural unit (e) described later.

[0096] In the copolymer (P), at least a portion of the carboxyl salt preferably comprises structural unit (b) as shown in the following general formula (5). This is because the carboxyl salt is present in a relatively large amount by mass, allowing the carboxyl salt to be effectively contained in the copolymer (P). The proportion of the carboxyl salt contained in structural unit (b) in the copolymer (P) is preferably 95 mol% or more, more preferably 98 mol% or more, and even more preferably 99 mol% or more.

[0097]

[0098] In general formula (5), R 2 This represents a hydrogen atom or a methyl group, where X is a cation.

[0099] In general formula (5), X is more preferably a monovalent cation, and even more preferably at least one of lithium ion, sodium ion, potassium ion, and ammonium ion. Particularly preferred is the presence of at least one of lithium ion and sodium ion.

[0100] As structural unit (b), in the above general formula (5), the copolymer (P) may contain two or more structures with different X. For example, structural unit (b) may include both lithium salt and sodium salt structures.

[0101] [1-1-3. Substituent (c)]

[0102] The substituent (c) is represented by the following general formula (1).

[0103]

[0104] In general formula (1), R 31 It is a hydrocarbon group, where m and n represent the groups with respect to R. 31 The number of directly bonded substituents (the number of branches of the structure within parentheses corresponding to m and n respectively), where m is an integer greater than or equal to 0, n is an integer greater than or equal to 1, m + n ≥ 2, R 32 It can be a hydrogen atom or a methyl group.

[0105] Substituent (c) has the function of connecting the main chains to each other and extending the molecular chains. If n≥3, a cross-linked structure can be formed in the copolymer (P).

[0106] In general formula (1), m+n≥3 is preferred, and m+n≥4 is more preferred. This is because the electrode active material layer containing copolymer (P) improves the peel strength and toughness of the current collector, which can be considered as at least a portion of the substituent (c) forming the crosslinked structure in copolymer (P).

[0107] Furthermore, although not particularly limited, m+n≤6 is preferred, more preferably m+n≤5. Further preferred is m+n≤4, and particularly preferred is m+n=4. This is to improve the flexibility of the electrode active material layer containing the copolymer (P).

[0108] In general formula (1), R 31 Preferably, it is composed of carbon atoms and hydrogen atoms. More preferably, R 31 It has multiple carbon atoms, and all the bonds between the carbon atoms are single bonds.

[0109] In general formula (1), R 31It can be a straight-chain hydrocarbon group or a branched hydrocarbon group. R 31 The number of carbon atoms contained therein is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. Furthermore, R is preferred. 31 It does not directly integrate with the aforementioned main chain. In R 31 In this process, all bonds between carbon atoms are preferably single bonds. This is to improve the flexibility of the substituents (c) and the suppleness of the electrode adhesive.

[0110] In general formula (1), R 32 Methyl groups are preferred. This is to improve the peel strength of the electrode active material layer containing copolymers (P).

[0111] When the formula weight of the substituent (c) is set to Mc, it is preferable that Mc / (m+n) ≤ 400, more preferably Mc / (m+n) ≤ 300, and even more preferably Mc / (m+n) ≤ 200. This is to improve the effect of extending the molecular chain by the substituent (c) and / or increasing the crosslinking density of the copolymer (P), thereby improving the peel strength of the electrode active material layer relative to the current collector and the toughness of the electrode active material layer.

[0112] The substituent (c) is a structural unit derived from the polyfunctional thiol compound (C), which preferably has two or more thiol groups per molecule. More preferably, the polyfunctional thiol compound (C) has three or more thiol groups per molecule, and even more preferably four or more. Details regarding the polyfunctional thiol compound (C) will be described later in the section on the method for manufacturing the copolymer (P).

[0113] The amount of substituent (c) contained in each 1g of copolymer (P) is 0.15 × 10⁻⁶. -2 mmol / g or higher, preferably 0.30×10 -2 mmol / g or higher, more preferably 0.65×10 -2 mmol / g or higher. This is to improve the strength of the composite material layer of the electrode in the electrode described later, and to improve the discharge capacity retention rate after charge-discharge cycles.

[0114] The amount of substituents (c) contained in each 1g of copolymer (P) is 8.0 × 10⁻⁶. -2 Below mmol / g, preferably 5.5 × 10⁻⁶. - 2 Below mmol / g, more preferably 4.0 × 10 mmol / g -2 Below mmol / g, and more preferably 1.4 × 10⁻⁶. -2 Below mmol / g. This is to improve the flexibility of the electrode in the electrode described later. Additionally, it is to improve cycle characteristics (discharge capacity retention) in the non-aqueous secondary battery described later.

[0115] [1-1-4. Structural Unit (d)]

[0116] The structural unit (d) is a structure represented by the following general formula (2).

[0117]

[0118] In general formula (2), R 41 R 42 R 44 Each can be independently an alkyl group having 1 to 5 hydrogen atoms or carbon atoms. 43 It is an alkyl group with 1 to 6 carbon atoms, and the number of carbon atoms is greater than that of R. 42 Many. In this formula, j and k represent the number of structures connected in series within the corresponding parentheses. j is an integer greater than or equal to 1, k is an integer greater than or equal to 0, and j + k ≥ 20.

[0119] In general formula (2), R 41 R 42 R 44 Each is preferably an alkyl group having 1 to 3 carbon atoms, R. 41 R 42 R 44 More preferably, independently, it is a hydrogen atom or a methyl group. R 44 More preferably, it is methyl.

[0120] In general formula (2), j is an integer greater than or equal to 1, k is an integer greater than or equal to 0, and j+k≥20. This is to improve the flexibility of the electrode and suppress crack formation when the copolymer (P) is used as a binder for the electrode active material. From this point of view, j+k≥30 is preferred, and j+k≥40 is more preferred. In addition, j+k≤500 is preferred, j+k≤200 is more preferred, and j+k≤150 is even more preferred. This is because the bonding strength of the electrode binder becomes higher.

[0121] Furthermore, in general formula (2), the inclusion of R is specified. 42 j structural units and containing R 43The number of structural units is k, but the arrangement of these structural units is not limited. That is, when k≥1, the polyoxyalkylene chain of general formula (2) can have a block structure in which all or part of each structural unit is continuous, or a structure with a periodic and regular arrangement such as alternating arrangement of two structural units, or a structure with a random arrangement of two structural units. The preferred form of the polyoxyalkylene chain of general formula (2) is a structure with a periodic and regular arrangement or a structure with a random arrangement. This is to suppress the deviation in the distribution of each structural unit within the molecular chain forming general formula (2). The more preferred form of the copolymer of general formula (2) is a structure with a random arrangement. This is so that polymerization can be carried out by free radical polymerization initiator without the use of special catalysts, which can reduce manufacturing costs.

[0122] In general formula (2), as R 41 R 42 R 43 R 44 The following Table 1 lists examples of preferred combinations of j and k.

[0123] [Table 1]

[0124]

[0125] The content of structural unit (d) in the copolymer (P) is preferably 0.50% by mass or more, more preferably 0.70% by mass or more, and even more preferably 3.5% by mass or more. This is to suppress the generation of cracks in the electrode, which will be described later.

[0126] The content of structural unit (d) in the copolymer (P) is preferably 20.0% by mass or less, more preferably 14.0% by mass or less, and even more preferably 7.0% by mass or less. This is to improve the peel strength of the electrode active material layer. Furthermore, it is to improve cycle characteristics (discharge capacity retention) in the non-aqueous secondary battery described later.

[0127] [1-1-5. Structural Unit (e)]

[0128] The structural unit (e) is a structure represented by the following general formula (3).

[0129]

[0130] In general formula (3), R 51 R represents a hydrogen atom or a methyl group. 52 It is a substituent with an aromatic ring. R 52 The aromatic ring contained therein is preferably one. Preferably, R... 52 None of the salts containing an amide bond or a carboxyl group. R 52 Preferably, it has a benzene ring, and more preferably, it is composed of carbon atoms and hydrogen atoms.

[0131] The structural unit (e) is preferably represented by the following general formula (6).

[0132]

[0133] In general formula (6), R 51 It can be a hydrogen atom or a methyl group. R 53 It is -CH2-, -(CH2CH2O)h-, or -CH2CH(OH)CH2O-. Here, h is an integer between 1 and 5. 54 It is a substituent with an aromatic ring. R 53 More preferably, it is -CH2- or -CH2CH2O-, and even more preferably -CH2-. R 54 The aromatic ring contained therein is preferably one. R 54 Preferably, it has a benzene ring, more preferably it is composed of carbon and hydrogen atoms. R is preferred. 54 None of the salts containing an amide bond or a carboxyl group. R 54 Phenyl is particularly preferred.

[0134] The amount of structural unit (e) contained in each 1g of copolymer (P) is preferably 0.030 mmol / g or more, more preferably 0.045 mmol / g or more, and even more preferably 0.30 mmol / g or more. This is to suppress the generation of electrode cracks as described later and improve electrode productivity.

[0135] The amount of structural unit (e) contained in each 1g of copolymer (P) is preferably 1.75 mmol / g or less, more preferably 1.50 mmol / g or less, and even more preferably 0.90 mmol / g or less. This is to improve the peel strength of the electrode active material layer and suppress the expansion of the electrode active material layer in the electrode described later. In addition, it is to improve the cycle characteristics (discharge capacity retention) in the non-aqueous secondary battery described later.

[0136] [1-1-6. Other Structures]

[0137] Other structures contained in the copolymer (P) include structures at the ends of the molecular chains and structures other than those branching from the main chain.

[0138] Structures at the ends of the molecular chain can include, for example, structures derived from polymerization initiators and structures derived from chain transfer agents. Furthermore, substituents (c), for example, are not considered as end-chain structures even if n=1 in general formula (1). The content of end-chain structures in the copolymer (P) is preferably 10% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less. This is to further improve the effect of the aforementioned structures in the copolymer (P). Additionally, the structure derived from a single chain transfer agent has only one binding site with the molecular chain of the copolymer (P).

[0139] Other structures included in the copolymer (P) besides those described above can be listed as carboxyl groups. When the copolymer (P) has carboxyl groups, the amount of carboxyl groups contained in 1g of copolymer (P) is preferably 0.030 mmol / g or more, more preferably 1.5 mmol / g or more. The amount of carboxyl groups contained in 1g of copolymer (P) is preferably 5.0 mmol / g or less, more preferably 3.0 mmol / g or less.

[0140] The copolymer (P) may contain structures that do not belong to any of the following: a main chain formed by bonds between carbon atoms, substituents (c), ester bonds, amide bonds, salts of carboxyl groups, structural units (d), structural units (e), and carboxyl groups. Its content is preferably 0.50 mmol / g or less, more preferably 0.30 mmol / g or less, and even more preferably 0.10 mmol / g or less. This is to more strongly utilize the effects of the functional groups and structures contained in the copolymer (P).

[0141] [1-1-7. Examples of preferred structures of copolymers (P)]

[0142] Examples of preferred structures for copolymers (P) include copolymers having structural units (a) of general formula (4), structural units (b) of general formula (5), and substituents (c) of general formula (1). In such copolymers, the ends of the molecular chains may also have structures derived from an initiator and structures derived from a chain transfer agent, etc. The content of each structural unit is determined by the amount of functional groups and structures introduced into the copolymer (P). The amounts of functional groups and structures contained in the copolymer (P) are as described above. In this example, the total content of structural units (a), structural units (b), and substituents (c) in the copolymer (P) is preferably 97.0% by mass or more, more preferably 98.0% by mass or more, and even more preferably 99.0% by mass or more.

[0143] Another example of a preferred structure for copolymer (P) is a copolymer that, in addition to structural unit (a), structural unit (b), and substituent (c), also has one or both of the aforementioned structural units (d) and (e). In this copolymer, the molecular chain ends may also have structures derived from an initiator and structures derived from a chain transfer agent, etc. The content of each structural unit is determined by the amount of functional groups and structures introduced into the copolymer (P). The amounts of functional groups and structures contained in the copolymer (P) are as described above. In this example, the total content of structural units (a), (b), (c), (d), and (e) in the copolymer (P) is preferably 97.0% by mass or more, more preferably 98.0% by mass or more, and even more preferably 99.0% by mass or more.

[0144] [1-2. Method for manufacturing copolymer (P)]

[0145] The method for producing the copolymer (P) is not particularly limited, but it is preferable to carry out free radical polymerization of a monomer (M) having an olefinic unsaturated double bond in the presence of a polyfunctional thiol compound (C) having two or more thiol groups per molecule. The polymerization is preferably carried out in an aqueous medium. As a polymerization step, for example, methods can be used such as adding all the monomer (M) used in the polymerization at once, or continuously supplying the monomer (M) used in the polymerization while carrying out the polymerization. The polymerization temperature is not particularly limited, but is preferably 30°C to 90°C.

[0146] As monomers (M), monomers (A) having amide bonds and monomers (B) having carboxyl salts are preferred to simplify the manufacturing process. When synthesizing copolymers (P) containing structural units (d), monomers (D) represented by general formula (10) described later are preferred to simplify the manufacturing process. When synthesizing copolymers (P) containing structural units (e), monomers (E) represented by general formula (11) described later are preferred to simplify the manufacturing process. Alternatively, these monomers may not be used, and the necessary functional groups may be formed through post-polymerization reactions, etc.

[0147] [1-2-1. Monomer (A)]

[0148] Monomer (A) has an olefinic unsaturated double bond and an amide bond. Additionally, in the case where monomer (A) is a salt containing a carboxyl group, this monomer (A) is also equivalent to monomer (B). Monomer (A) preferably has a (meth)acryloyloxy group. This is because the polymerization rate increases, and the productivity of the copolymer (P) increases. More preferably, monomer (A) has a structure represented by the following general formula (7).

[0149]

[0150] R in general formula (7)11 R 12 Similar to the structures in general formula (4) above. A particularly preferred example of monomer (A) is N-vinylformamide (R 11 :H and R 12 :H) or N-vinylacetamide (R 11 :H and R 12 (CH3). This is because the amide bond has a larger mass relative to the monomer (A), and the copolymer (P) can contain more amide bonds.

[0151] [1-2-2. Monomer (B)]

[0152] Monomer (B) is a salt having an olefinic unsaturated double bond and a carboxyl group. Additionally, if monomer (B) has an amide bond, it is equivalent to monomer (A). Monomer (B) preferably has a (meth)acryloyloxy group. This is because the polymerization rate increases, leading to a higher yield of copolymer (P). More preferably, monomer (B) has a structure represented by the following general formula (8).

[0153]

[0154] R in general formula (8) 2 X has the same structure as those in general formula (5) above. As monomer (B), more than two compounds different from X in general formula (8) can be used. For example, lithium salt and sodium salt can be used as monomer (B).

[0155] [1-2-3. Polyfunctional thiols (C)]

[0156] The polyfunctional thiol compound (C) has two or more thiol groups. The polyfunctional thiol compound (C) is preferably represented by the following general formula (9). This is because it is inexpensive and readily available, and the reaction rate is increased, leading to a higher yield of copolymer (P).

[0157]

[0158] R in general formula (9) 32 The structure is the same as in general formula (1) above. R 33 It is a hydrocarbon group. f indicates that it is directly attached to R. 33 The number of corresponding substituents (the number of branches of the structure in parentheses). f≥2.

[0159] Preferably, f ≥ 3, more preferably f ≥ 4. This is because a cross-linked structure can be formed in the copolymer (P), thereby improving the peel strength and toughness of the electrode active material layer containing the copolymer (P) to the current collector. Additionally, although not particularly limited, f ≤ 6 is preferred, more preferably f ≤ 5, further preferably f ≤ 4, and most preferably f = 4. This is to improve the flexibility of the electrode active material layer containing the copolymer (P).

[0160] In general formula (9), R 33 It can be a straight-chain hydrocarbon group or a branched hydrocarbon group. R 33 The number of carbon atoms contained therein is preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less. Additionally, R 33 Preferably, it does not have olefinic unsaturated double bonds. This is to suppress deviations and excesses in crosslinking density.

[0161] The thiol equivalent (the average molecular weight corresponding to one thiol group) of the polyfunctional thiol compound (C) is preferably 400 or less, more preferably 300 or less, and even more preferably 200 or less. This is because the polyfunctional thiol compound (C) extends the molecular chain and / or increases the crosslinking density of the copolymer (P), thereby improving the peel strength of the electrode active material layer relative to the current collector and the toughness of the electrode active material layer.

[0162] For the same reason, when the polyfunctional thiol compound (C) is the compound shown in formula (9), if the molecular weight of the polyfunctional thiol compound (C) is set to MC, it is preferable that MC / f ≤ 400, more preferably MC / f ≤ 300, and even more preferably MC / f ≤ 200.

[0163] Examples of polyfunctional thiol compounds (C) include pentaerythritol = tetra(3-mercaptobutyrate), pentaerythritol = tetra(3-mercaptopropionate), trimethylolpropane = tri(3-mercaptobutyrate), trimethylolpropane = tri(3-mercaptopropionate), tri(3-mercaptopropionyloxy)-ethyl[3-isocyanurate], 1,4-bis(3-mercaptobutyryloxy)butane, tetraethyleneol = bis(3-mercaptopropionate), and dipentaerythritol = hexa(3-mercaptopropionate). As monomers (C), these compounds are further preferably found to contain pentaerythritol = tetra(3-mercaptobutyrate), pentaerythritol = tetra(3-mercaptopropionate), trimethylolpropane = tri(3-mercaptobutyrate), and 1,4-bis(3-mercaptobutyryloxy)butane.

[0164] [1-2-4. Monomer (D)]

[0165] The monomer (D) is represented by the following general formula (10).

[0166]

[0167] R in general formula (10) 41 R 42 R 43 R 44 The structures of j and k are the same as those in the general formula (2) above.

[0168] In general formula (10), k = 0 is more preferred. Examples of monomers (D) with k = 0 include polyethylene glycol mono(meth)acrylates, and more specifically, methoxy polyethylene glycol (meth)acrylates (e.g., monomers d1 and d2 in Table 1). An example of a methoxy polyethylene glycol methacrylate is VISIOMER (registered trademark) MPEG2005MA W manufactured by EVONIKINDUSTRIES. In this product, R 41 =CH3,R 42 =H,R 44 =CH3, j=45, k=0. Other examples of methoxy polyethylene glycol methacrylate include VISIOMER MPEG5005MA W manufactured by EVONIKINDUSTRIES, in which R... 41 =CH3,R 42 =H,R 44 =CH3, j=113, k=0.

[0169] Another example of a monomer (D) with k=0 is polypropylene glycol mono(meth)acrylate, and more specifically, methoxy polypropylene glycol (meth)acrylate, etc.

[0170] [1-2-5. Monomer (E)]

[0171] The monomer (E) is represented by the following general formula (11).

[0172]

[0173] R in general formula (11) 51 and R 52 The same structures as those in general formula (3) above.

[0174] The monomer (E) is preferably represented by the following general formula (12).

[0175]

[0176] R in general formula (12) 51 R 53 and R 54 The same structures as those in general formula (6) above.

[0177] Examples of monomers (E) include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxyethylene glycol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, ethoxylated o-phenylphenol (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate. More preferably, one or both of these compounds, benzyl (meth)acrylate and phenoxyethyl (meth)acrylate, are used as monomers (E).

[0178] [1-2-7. Polymerization Initiator]

[0179] In the case of free radical polymerization, examples of polymerization initiators include, but are not limited to, hydrogen peroxide, tert-butyl hydroperoxide, and azo compounds. Examples of azo compounds include, for example, 2,2'-azobis(2-methylpropanediamine)2 hydrochloride. When polymerization is carried out in water, water-soluble polymerization initiators are preferred. Alternatively, redox polymerization can be performed using both a free radical polymerization initiator and a reducing agent, as needed. Examples of reducing agents include sodium bisulfite, margarine, and ascorbic acid. Furthermore, when using an azo compound as a polymerization initiator, components such as persulfates can be added to assist in the generation of free radicals from the azo compound, but these components do not constitute a copolymer (P). Examples of persulfates include ammonium persulfate and potassium persulfate.

[0180] [1-2-8. Aqueous Media]

[0181] Water is preferred as the aqueous medium, but substances containing a hydrophilic solvent added to water may also be used as the aqueous medium, provided that the polymerization stability of the resulting adhesive copolymer is not compromised. Examples of hydrophilic solvents that can be added to water include methanol, ethanol, and N-methylpyrrolidone.

[0182] [1-2-9. Chain transfer agents]

[0183] During polymerization, chain transfer agents can also be used to adjust the molecular weight of the copolymer (P). There are no particular limitations on chain transfer agents, and examples include monofunctional thiols such as β-mercaptopropionic acid and octyl mercaptoacetate, alcohols such as isopropanol and ethanol, halogenated hydrocarbons such as carbon tetrabromide and carbon tetrachloride, and α-methylstyrene dimers.

[0184] [1-2-10. Content of each component in the polymer composition]

[0185] If the compounds that become part of the copolymer (P) structure through polymerization are considered as the polymerization components, then the polymerization components include the monomers, chain transfer agents, and polymerization initiators. The composition of the polymerization components is determined by the amount of functional groups and structures introduced into the copolymer (P). In the case of free radical polymerization, unless operations are performed to change specific functional groups, all monomers become structural units of the copolymer (P) without reacting to the parts other than the olefinic unsaturated double bonds. Furthermore, in the case of free radical polymerization, unless operations are performed to change specific functional groups, all polyfunctional thiols (C) become substituents (c) of the copolymer (P).

[0186] In the synthesis of copolymers (P), forms that do not use monomers (D) and monomers (E) can be listed, as well as forms that use one or both of monomers (D) and monomers (E).

[0187] Hereinafter, suitable amounts of each monomer and the polyfunctional thiol compound (C) used to obtain the copolymer (P) of the present invention will be described, but are not limited thereto. Here, when using the monomer, polyfunctional thiol compound (C), polymerization initiator and chain transfer agent for synthesizing the copolymer (P), the chain transfer agent is also referred to as a polymerization component.

[0188] The amount of monomer (A) contained in each 1g of polymeric component is preferably 0.050 mmol / g or more, more preferably 0.085 mmol / g or more, and even more preferably 0.40 mmol / g or more. The amount of monomer (A) contained in each 1g of polymeric component is preferably 5.0 mmol / g or less, more preferably 3.0 mmol / g or less, even more preferably 1.7 mmol / g or less, and particularly preferably 0.90 mmol / g or less.

[0189] The amount of monomer (B) contained in each 1g of the polymer component is preferably 5.0 mmol / g or more, more preferably 6.0 mmol / g or more, and even more preferably 7.0 mmol / g or more. The amount of monomer (B) contained in each 1g of the polymer component is preferably 12.0 mmol / g or less, more preferably 9.9 mmol / g or less. In addition, when a plurality of carboxylate ions corresponding to the structure of monomer (B) are bonded to a cation with a valence of divalent or higher, it is considered that there is a quantity of monomer (B) bonded to that cation.

[0190] The amount of polyfunctional thiol compounds (C) contained in each 1g of polymer component is 0.15 × 10⁻⁶. -2 mmol / g or higher, preferably 0.30×10 -2 mmol / g or higher, more preferably 0.65×10 -2 mmol / g or higher. The amount of polyfunctional thiol compounds (C) contained in each 1g of polymeric component is 8.0 × 10⁻⁶.-2 Below mmol / g, preferably 5.5 × 10⁻⁶. -2 Below mmol / g, more preferably 4.0 × 10 mmol / g -2 Below mmol / g, and more preferably 1.4 × 10⁻⁶. -2 Below mmol / g.

[0191] The monomer (D) content in the polymerizing component is preferably 0.50% by mass or more, more preferably 0.70% by mass or more, and even more preferably 3.5% by mass or more. The monomer (D) content in the polymerizing component is preferably 20.0% by mass or less, more preferably 14.0% by mass or less, and even more preferably 7.0% by mass or less.

[0192] The amount of monomer (E) contained in each 1g of polymeric component is preferably 0.030 mmol / g or more, more preferably 0.045 mmol / g or more, and even more preferably 0.30 mmol / g by mass% or more. The amount of monomer (E) contained in each 1g of polymeric component is preferably 1.75 mmol / g or less, more preferably 1.50 mmol / g by mass% or less, and even more preferably 0.90 mmol / g by mass% or less.

[0193] The content of the chain transfer agent in the polymerization component is not particularly limited, but is preferably 0.10% by mass or more, more preferably 0.25% by mass or more, and even more preferably 0.35% by mass or more. The content of the chain transfer agent in the polymerization component is not particularly limited, but is preferably 10% by mass or less, more preferably 2.0% by mass or less, and even more preferably 0.70% by mass or less.

[0194] The preferred amount of chain transfer agent per 1g of polymer component is 1.0 × 10⁻⁶. -2 mmol / g or higher, more preferably 2.0 × 10 mmol / g -2 mmol / g or higher, and more preferably 3.0 × 10 mmol / g. -2 mmol / g or higher. The preferred amount of chain transfer agent per 1g of polymeric component is 20 × 10⁻⁶ mmol / g. -2 Below mmol / g, more preferably 10×10 -2 Below mmol / g, more preferably 7.0 × 10 mmol / g -2 Below mmol / g.

[0195] The content of the polymerization initiator in the polymerization component is preferably 0.020% by mass or more, more preferably 0.10% by mass or more, and even more preferably 0.15% by mass or more. The content of the polymerization initiator in the polymerization component is preferably 1.0% by mass or less, more preferably 0.50% by mass or less, and even more preferably 0.35% by mass or less. Here, components such as reducing agents that do not contribute to the structure of the copolymer (P) and function as auxiliary polymerization initiators are not included.

[0196] The preferred amount of polymerization initiator per 1g of polymerization component is 0.10 × 10⁻⁶. -2 mmol / g or higher, more preferably 0.20 × 10 mmol / g -2 mmol / g or higher, and more preferably 0.50 × 10 mmol / g. -2 mmol / g or higher. The preferred amount of polymerization initiator per 1g of polymeric component is 5.0 × 10⁻⁶ mmol / g. -2 Below mmol / g, more preferably 2.0 × 10 mmol / g -2 Below mmol / g, and more preferably 1.0 × 10⁻⁶. - 2 Below mmol / g. This excludes components such as reducing agents that do not contribute to the structure of the copolymer (P) and function as auxiliary polymerization initiators.

[0197] As an example of a method for synthesizing copolymer (P), the total content of monomers represented by general formula (7) and monomers represented by general formula (8) in monomer (M) (all monomers) is 90% by mass or more, preferably 95% by mass or more, and more preferably 100% by mass.

[0198] As another example, structures using one or both of monomers (D) and (E) can be cited. In this example, the total content of monomers (M) (all monomers) represented by general formula (7), general formula (8), general formula (10), and general formula (11) is 90% by mass or more, preferably 95% by mass or more, and more preferably 100% by mass.

[0199] [1-3. Manufacturing method of non-aqueous secondary battery electrode binder]

[0200] A method for manufacturing a non-aqueous secondary battery electrode adhesive includes a polymerization step of free radical polymerization of a monomer (M) having an olefinic unsaturated double bond in the presence of a polyfunctional thiol compound (C) having two or more thiol groups in one molecule.

[0201] The manufacturing method of the non-aqueous secondary battery electrode binder can be the same as that of the copolymer (P), or it can include further steps. The manufacturing method of the copolymer (P) is as described above. Further steps may include, for example, purification steps and additive mixing steps.

[0202] <2. Adhesive Composition for Non-Aqueous Secondary Battery Electrodes>

[0203] The non-aqueous secondary battery electrode binder composition of this embodiment (hereinafter sometimes referred to as the "electrode binder composition") comprises an electrode binder and an aqueous medium. Additionally, the electrode binder composition may contain other components such as pH adjusters and surfactants, as needed.

[0204] The aqueous medium contained in the electrode adhesive composition comprises water. The aqueous medium contained in the electrode adhesive composition may contain a hydrophilic solvent. Examples of hydrophilic solvents include methanol, ethanol, and N-methylpyrrolidone. The water content in the aqueous medium contained in the electrode adhesive composition is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0205] The composition of the aqueous medium contained in the electrode binder composition may be the same as or different from the aqueous medium used to synthesize the copolymer (P). Furthermore, in the electrode binder composition of this embodiment, the electrode binder may be dissolved in the aqueous medium or dispersed.

[0206] The copolymer (P) content in the electrode binder composition is preferably 30% by mass or less, more preferably 20% by mass or less. This is to suppress the increase in viscosity of the electrode binder composition and to efficiently disperse the electrode active material when mixed with the electrode active material described later in the preparation of the electrode slurry.

[0207] The copolymer (P) content in the electrode binder composition is preferably 3.0% by mass or more, more preferably 5.0% by mass or more, and even more preferably 8.0% by mass or more. This is because electrode pastes and electrodes can be made from a smaller amount of electrode binder composition.

[0208] The pH of the electrode binder composition is preferably 4.0 or higher, more preferably 5.0 or higher, and even more preferably 6.0 or higher. This is to ensure efficient dispersion of the electrode active materials when mixed with the electrode active materials described later to prepare the electrode slurry. The pH of the electrode binder composition is preferably 11 or lower, more preferably 10 or lower, and even more preferably 9.0 or lower. This is to ensure efficient dispersion of the electrode active materials when mixed with the electrode active materials described later to prepare the electrode slurry. Here, the pH is a value measured by a pH meter at a liquid temperature of 23°C.

[0209] <3. Non-aqueous secondary battery electrode slurry>

[0210] In the non-aqueous secondary battery electrode slurry (hereinafter sometimes referred to as "electrode slurry") of this embodiment, the electrode binder and electrode active material are dissolved or dispersed in an aqueous medium. The electrode slurry of this embodiment may contain conductive additives, thickeners, etc., as needed, but to simplify the electrode slurry preparation process, it is preferable not to contain thickeners. There are no particular limitations on the method for preparing the electrode slurry; for example, methods using mixing devices such as stirring, rotating, or vibrating mixers to mix the desired components can be listed.

[0211] The concentration of non-volatile components in the electrode slurry is preferably 30% by mass or more, more preferably 40% by mass or more. This is to form a larger layer of active electrode material with a smaller amount of electrode slurry. The concentration of non-volatile components in the electrode slurry is preferably 70% by mass or less, more preferably 60% by mass or less. The concentration of non-volatile components can be adjusted by the amount of aqueous medium.

[0212] Here, the so-called concentration of non-volatile components, unless otherwise specified, is the ratio of the mass of the remaining component to the mass before drying, after weighing 1g of the mixture onto an aluminum pan with a diameter of 5cm and drying it at 130°C for 1 hour under atmospheric pressure and air circulation in a desiccator.

[0213] [3-1. Content of copolymer (P) in electrode paste]

[0214] The content of copolymer (P) in the electrode slurry is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, and even more preferably 2.0% by mass or more, relative to the total mass of the electrode active material (described later), conductive additive (described later), and electrode binder. This is because the copolymer (P) ensures adhesion between electrode active materials and between the electrode active material and the current collector. The content of copolymer (P) in the electrode slurry is preferably 10% by mass or less, more preferably 7.0% by mass or less, and even more preferably 4.0% by mass or less, relative to the total mass of the electrode active material, conductive additive, and electrode binder. This is because the charge / discharge capacity of the electrode active material layer formed by the electrode slurry can be increased, and the internal resistance when used as a battery can also be reduced.

[0215] [3-2. Electrode Active Materials]

[0216] There are no particular limitations for non-aqueous secondary batteries. In the case of lithium-ion secondary batteries, examples of negative electrode active materials include conductive polymers, carbon materials, lithium titanate, silicon, and silicon compounds. Examples of conductive polymers include polyacetylene and polypyrrole. Examples of carbon materials include petroleum coke, pitch coke, coal coke, and other cokes; carbides of organic compounds; and graphite such as artificial graphite and natural graphite. Examples of silicon compounds include SiOx (0.1 ≤ x ≤ 2.0).

[0217] Alternatively, composite materials containing Si and graphite (Si / graphite) can be used as electrode active materials. Among these active materials, carbon materials, lithium titanate, silicon, and silicon compounds are preferred from the viewpoint of maximizing energy density per volume. Furthermore, using carbon materials such as coke, carbides of organic compounds, and graphite, or silicon-containing materials such as SiOx (0.1 ≤ x ≤ 2.0), Si, and Si / graphite significantly improves the adhesion of the electrode binder in this embodiment. For example, SCMG (registered trademark)-XRs (manufactured by Showa Denko Co., Ltd.) can be cited as a specific example of artificial graphite. Additionally, two or more of the materials listed here can be combined as negative electrode active materials.

[0218] Examples of positive electrode active materials for lithium-ion secondary batteries include lithium cobalt oxide (LiCoO2), nickel-containing lithium composite oxides, spinel-type lithium manganese oxide (LiMn2O4), olivine-type lithium iron phosphate, TiS2, MnO2, MoO3, V2O5, and other chalcogenides. The positive electrode active material can contain any one of these compounds alone, or multiple compounds. Additionally, oxides of other alkali metals can also be used. Examples of nickel-containing lithium composite oxides include Ni-Co-Mn lithium composite oxides, Ni-Mn-Al lithium composite oxides, and Ni-Co-Al lithium composite oxides. A specific example of a positive electrode active material is LiNi... 1 / 3 Mn 1 / 3 Co 1 / 3 O2 or LiNi 3 / 5 Mn 1 / 5 Co 1 / 5 wait.

[0219] [3-3. Conductive additives]

[0220] Electrode pastes may contain carbon black, fumed carbon fibers, etc., as conductive additives. A specific example of fumed carbon fibers is VGCF (registered trademark)-H (Showa Denko Co., Ltd.).

[0221] [3-4. Aqueous Media]

[0222] The aqueous medium of the electrode paste contains water. The aqueous medium of the electrode paste may contain a hydrophilic solvent. Hydrophilic solvents include methanol, ethanol, and N-methylpyrrolidone. The water content in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The composition of the aqueous medium of the electrode paste may be the same as or different from the aqueous medium contained in the electrode binder composition.

[0223] <4. Electrodes>

[0224] The electrode of this embodiment has a current collector and an electrode active material layer formed on the surface of the current collector. The electrode active material layer includes an electrode active material and the electrode binder of this embodiment. As for the shape of the electrode, examples include laminated bodies or wound bodies, but there are no particular limitations. The current collector is preferably a metal sheet with a thickness of 0.001 to 0.5 mm. Examples of metals that can be used as the current collector include iron, copper, aluminum, nickel, and stainless steel. In the case of a lithium-ion secondary battery (non-aqueous secondary battery), aluminum is preferred as the current collector for the positive electrode, and copper is preferred as the current collector for the negative electrode, but there are no particular limitations.

[0225] The electrode in this embodiment can be manufactured, for example, by coating an electrode paste onto a current collector and drying it, but is not limited to this method.

[0226] Methods for coating electrode paste onto a current collector include, for example, 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 dip method, and the squeezing method. Among these, the doctor blade method, the knife method, or the extrusion method are preferred, and the use of a doctor blade is more preferred. This is because the various physical properties of the electrode paste, such as viscosity, and its drying properties are suitable, resulting in a coating film with a good surface condition.

[0227] 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 one side at a time or simultaneously to both sides. Furthermore, the electrode paste can be applied continuously or intermittently to the surface of the current collector. The amount and range of the electrode paste applied can be appropriately determined based on factors such as the size of the battery. The preferred weight per unit area of ​​the dried electrode active material layer is 4–20 mg / cm². 2 More preferably 6–16 mg / cm³ 2 .

[0228] Electrode sheets can be obtained by drying the electrode paste applied to the current collector. The drying method is not particularly limited; for example, hot air, vacuum, (far)infrared radiation, electron beams, microwaves, and low-temperature air can be used alone or in combination. The drying temperature is preferably between 40°C and 180°C, and the drying time is preferably between 1 minute and 30 minutes.

[0229] Electrode sheets can be used directly as electrodes, or they can be cut into appropriate sizes or shapes for use as electrodes. There are no particular limitations on the cutting methods for electrode sheets; for example, slit cutting, laser cutting, wire cutting, wire cutting tools, Thomson scalpels, etc., can be used.

[0230] Before or after cutting the electrode sheets, they can be pressed as needed. This allows for the strong bonding of the electrode active materials through the electrodes, and further enables the miniaturization of non-aqueous batteries by thinning the electrodes. As for the pressing method, general methods can be used, but die pressing or roller pressing is particularly preferred. The pressing pressure is not particularly limited, but is preferably 0.5 to 5 t / cm² within a range that does not affect the doping / dedoping of the electrode active materials by lithium ions, etc. 2 .

[0231] <5. Battery>

[0232] As a preferred example of the battery in this embodiment, a lithium-ion secondary battery will be described, but the battery structure is not limited to the structure described below. In the lithium-ion secondary battery of this example, components such as the positive electrode, negative electrode, electrolyte, and separators as needed are housed in an outer casing. At least one of the positive and negative electrodes includes the electrode binder of this embodiment.

[0233] <5-1. Electrolyte>

[0234] As the electrolyte, a non-aqueous liquid with ion conductivity is used. Examples of electrolytes include solutions in which the electrolyte is dissolved in an organic solvent and ionic liquids, but the former is preferred because it can produce batteries with low manufacturing costs and low internal resistance.

[0235] 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 salts. Other alkali metal salts can also be used as electrolytes.

[0236] Organic solvents used to dissolve electrolytes are not particularly limited, and 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 vinylene carbonate (VC); nitrile compounds such as acetonitrile; and carboxylic acid esters such as ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, and propyl propionate. These organic solvents can be used alone or in combination of two or more.

[0237] <5-2. Exterior body>

[0238] As the outer casing, metal or aluminum laminate materials can be appropriately used. The battery shape can be any shape, such as coin-shaped, button-shaped, sheet-shaped, cylindrical, square, or flat.

[0239] Example

[0240] The present invention will be further described in detail below with examples and comparative examples of negative electrode binders, negative electrode slurries, negative electrodes, and lithium-ion secondary batteries. However, the present invention is not limited to these examples.

[0241] <1. Negative electrode adhesive>

[0242] [1-1. Synthesis of copolymers]

[0243] The compositions of the monomers, polyfunctional thiols (C), and chain transfer agents used in Examples 1-20 and Comparative Examples 1-5 are shown in Tables 2-4. Here, each monomer, polyfunctional thiols (C), chain transfer agent, and polymerization initiator shown in Tables 2-4 is referred to as a polymerization component. The details of each raw material compound shown in Tables 2-4 are as follows. When using monomers as solutions, the amounts of monomers in the tables represent the amount of the monomer itself without solvent.

[0244] It should be noted that polymerization initiators contain nitrogen and other components that are not absorbed by the polymer. However, since the amount of polymerization initiator used is small, the content (mass%) of each component in the polymerization composition and the number of moles of each component per 1g of polymerization composition in Tables 2-4 can be the content of the structure corresponding to each component in the generated copolymer and the number of moles of the structure corresponding to each component per 1g of copolymer.

[0245] Table 2

[0246]

[0247] Table 3

[0248]

[0249]

[0250] Monomer (A-1): N-vinylacetamide (NVA)

[0251] Monomer (B-1): Sodium acrylate (AaNa) (28.5% by mass aqueous solution)

[0252] Monomer (B-2): Lithium acrylate (AaLi) (28.5% by mass aqueous solution)

[0253] Aa: Acrylic acid

[0254] Polyfunctional thiols (C-1): Pentaerythritol tetra(3-mercaptobutyrate)

[0255] Polyfunctional thiols (C-2): Trimethylolpropane tris(3-mercaptobutyrate)

[0256] Polyfunctional thiol compound (C-3): 1,4-bis(3-mercaptobutyryloxy)butane

[0257] Polyfunctional thiols (C-4): Pentaerythritol tetra(3-mercaptopropionate)

[0258] Monomer (D-1): Methoxy polyethylene glycol methacrylate (EVONIK INDUSTRIES; VISIOMER (registered trademark) MPEG2005 MA W) (R in general formula (10) 41 =CH3,R 42 =H,R 44 =CH3, j=45, k=0, j+k=45) 50.0% by mass aqueous solution

[0259] Monomer (E-1): Benzyl acrylate

[0260] MPA: β-Mercaptopropionic acid

[0261] TMA: Tetramethylolmethane tetraacrylate

[0262] Polymerization initiators: 2,2'-azobis(2-methylpropanediamine)2 hydrochloride (manufactured by Wako Pure Chemical Industries, Ltd.; V-50) and ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.)

[0263] In a detachable flask equipped with a cooling tube, thermometer, stirrer, and dropping funnel, 100 parts by mass of the polymerization components corresponding to those in the examples and comparative examples (Tables 2-4), 0.050 parts by mass of ammonium persulfate, and 693 parts by mass of water were added at 30°C. The mixture was then heated to 80°C and polymerized for 4 hours to synthesize copolymers P1-CP20 and copolymers CP1-CP5, respectively.

[0264] [1-2. Preparation of the negative electrode binder composition]

[0265] Water was added to the reaction solution from which the copolymers were obtained to achieve a non-volatile component concentration of 10.0% by mass (the amount of water added was adjusted taking into account the water content in monomer (B-1)) to prepare negative electrode binder compositions Q1 to Q20 and CQ1 to CQ5. In the following description, copolymers P1 to P20 are sometimes referred to as copolymers (P) without distinction, and copolymers CP1 to CP5 are sometimes referred to as copolymers (CP) without distinction. Similarly, negative electrode binder compositions Q1 to Q20 are sometimes referred to as negative electrode binder compositions (Q) without distinction, and negative electrode binder compositions CQ1 to CQ5 are sometimes referred to as negative electrode binder compositions (CQ).

[0266] [1-3. Weight-average molecular weight of copolymer (P)]

[0267] The weight-average molecular weights of copolymers (P) and (CP) were determined using gel permeation chromatography (GPC) under the following conditions, and the results are shown in Table 4.

[0268] GPC device: GPC-101 (manufactured by Showa Denko Co., Ltd.)

[0269] Solvent: 0.1M NaNO3 aqueous solution

[0270] Sample column: Shodex Column Ohpak SB-806HQ (8.0mm I.D. × 300mm) × 2

[0271] Reference column: Shodex Column Ohpak SB-800RL (8.0mmI.D.×300mm)×2

[0272] Column temperature: 40℃

[0273] Sample concentration: 0.1% by mass

[0274] Detector: RI-71S (manufactured by Shimadzu Corporation)

[0275] Pump: DU-H2000 (manufactured by Shimadzu Corporation)

[0276] Pressure: 1.3 MPa

[0277] Flow rate: 1 ml / min

[0278] 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.)

[0279] <2. Negative Electrode Slurry>

[0280] [2-1. Preparation of negative electrode slurry]

[0281] 76.8 parts by weight of SCMG (registered trademark)-XRS (manufactured by Showa Denko Co., Ltd.) as graphite, 19.2 parts by weight of silicon monoxide (SiO) (manufactured by Sigma-Aldrich), 1.0 part by weight of VGCF (registered trademark)-H (manufactured by Showa Denko Co., Ltd.), 30 parts by weight of binder composition (Q) (containing 3.0 parts by weight of copolymer (P) and 27 parts by weight of water), and 20 parts by weight of water were mixed together. The mixing was carried out by kneading at 2000 rpm for 4 minutes using a stirring mixer (rotational-revolutionary mixer). 53 parts by weight of water were further added to the resulting mixture, and the mixture was further mixed at 2000 rpm for 4 minutes using the same mixing device to prepare the negative electrode slurry.

[0282] [2-2. Appearance Evaluation of Negative Electrode Slurry]

[0283] The appearance of the prepared negative electrode slurry was visually inspected to confirm its quality, and the size of the agglomerates was measured using a micrometer. The presence of agglomerates with a maximum size of 1 mm or more in 10 g of negative electrode slurry was considered an "×", while the absence of agglomerates with a maximum size of 1 mm or more was considered a "○". The evaluation results are shown in Table 5.

[0284] Table 5

[0285]

[0286] <3. Negative electrode>

[0287] [3-1. Flexibility of the negative electrode active material layer (winding test)]

[0288] The negative electrode slurry prepared as described above was applied to both sides of a 10 μm thick copper foil (current collector) using a scraper, and the dried slurry had a unit area weight of 8 mg / cm³. 2 Copper foil coated with negative electrode slurry is dried at 60°C for 10 minutes, then dried at 100°C for 5 minutes to produce a negative electrode sheet with a negative electrode active material layer. A die-pressing machine is used at a rate of 1 t / cm. 2 The negative electrode is suppressed by the pressure.

[0289] Here, the pressed negative electrode sheet is cut into test pieces with a width of 50 mm and a length of 60 mm. The test pieces are dried at 80°C for 12 hours. One side of the dried test piece in the width direction is fixed to a 3 mm diameter stainless steel rod using 50 μm thick single-sided tape (the width direction of the test piece is parallel to the length direction of the stainless steel rod). The other side of the test piece in the width direction is fixed to a glass plate. After winding the test piece around the stainless steel rod, the appearance of the test piece is visually observed, and the number of cracks on the test piece is counted.

[0290] [3-2. Stripping strength of the negative electrode active material layer to the current collector]

[0291] In addition to coating both sides of the copper foil with negative electrode paste, the dried unit area weight is 8 mg / cm³. 2 In addition, similar to the aforementioned evaluation of flexibility, a pressed negative electrode sheet is produced.

[0292] Using the negative electrode sheet pressed in this manner, the entire process was carried out in an atmosphere of 23°C and 50% relative humidity by mass. The testing machine used was Tensilon (registered trademark, manufactured by A. Ande Ltd.). The negative electrode sheet was cut into test pieces with a width of 25 mm and a length of 70 mm. Double-sided adhesive tape (NITTOTAPE No. 5, manufactured by Nitto Denko Ltd.) was used to bond the negative electrode active material layer on the test piece to a 50 mm wide and 200 mm long SUS plate, ensuring the center of the test piece was aligned with the center of the SUS plate. Furthermore, the double-sided adhesive tape was used to cover the entire area of ​​the test piece. Bonding was performed by repeatedly rolling a 2 kg roller back and forth once over the entire test piece.

[0293] After placing the test piece and SUS plate together for 10 minutes, the copper foil was peeled 20 mm from one end of the test piece along its length from the negative electrode active material, folded back 180°, and the peeled copper foil portion was held by the chuck on the upper side of the testing machine. Meanwhile, one end of the SUS plate with the peeled copper foil was held by the lower chuck. In this state, the copper foil was peeled from the test piece at a speed of 100 ± 10 mm / min, and a curve 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 curve, and the average peel force was divided by the width of the test piece (25 mm) to obtain the peel strength (mN / mm) of the negative electrode active material layer. Furthermore, in both 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.

[0294] <4. Lithium-ion secondary batteries>

[0295] [4-1. Battery Making]

[0296] [negative electrode]

[0297] Cut the pressed negative electrode sheet into 22mm×22mm pieces and install conductive sheets to make the negative electrode.

[0298] [positive electrode]

[0299] LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O290 parts by weight, acetylene black 5 parts by weight, and polyvinylidene fluoride 5 parts by weight are mixed, and then 100 parts by weight of N-methylpyrrolidone are mixed to prepare the positive electrode slurry (LiNi in the solid component). 1 / 3 Mn 1 / 3 Co 1 / 3 The proportion of O2 is 0.90.

[0300] The prepared positive electrode slurry was coated onto one side of a 20 μm thick aluminum foil (current collector) using a scraper method, resulting in a dry weight per unit area of ​​22.5 mg / cm². 2 (22.5×10 -3 g / cm 2 Aluminum foil coated with positive electrode slurry is dried at 120°C for 5 minutes, then pressed using a roller press to produce a positive electrode sheet with a positive electrode active material layer of 100 μm thickness. The obtained positive electrode sheet is cut into 20 mm × 20 mm (2.0 cm × 2.0 cm) pieces, and conductive sheets are attached to form the positive electrode.

[0301] The theoretical capacity of the fabricated positive electrode is determined by the unit area weight of the dried positive electrode slurry (22.5 × 10⁻⁶). -3 gg / cm 2 ) × Coating area of ​​positive electrode slurry (2.0cm × 2.0cm) × LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 The capacity of O2 as a positive electrode active material (160mAh / g) × LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 The value was calculated by determining the proportion of O2 in the solid component (0.90), resulting in a value of 13 mAh.

[0302] Electrolyte

[0303] An electrolyte was prepared by dissolving LiPF6 at a concentration of 1.0 mol / L and vinylene carbonate (VC) at a concentration of 1.0 wt% in a mixed solvent consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and fluoroethylene carbonate (FEC) in a volume ratio of 30:60:10.

[0304] [Battery assembly]

[0305] The positive and negative electrodes are arranged with their respective active material layers facing each other, separated by a separator made of a porous polyolefin membrane, and housed in an aluminum laminated casing (battery package). Electrolyte is injected into the casing, and it is sealed using a vacuum heat-sealing machine to obtain a laminated battery.

[0306] [4-2. Evaluation of battery cycle characteristics (discharge capacity retention)]

[0307] The cycle characteristics of the batteries fabricated in each embodiment and comparative example were evaluated. The evaluation method is as follows, and the evaluation results are shown in Table 5.

[0308] The battery's discharge capacity retention rate was determined (battery charge-discharge cycle test) under 25°C conditions, following these steps: First, the battery was charged at a current of 1C (CC charging) until the voltage reached 4.2V. Then, it was charged at 4.2V until the current reached 0.05C (CV charging). After being left to stand for 30 minutes, it was discharged at a current of 1C (CC discharging) until the voltage reached 2.75V. This series of operations—CC charging, CV charging, and CC discharging—was considered as one cycle. The sum of the time integral values ​​of the current during CC charging and CV charging in the nth cycle was taken as the charge capacity (mAh) of the nth cycle, and the time integral value of the current during CC discharging in the nth cycle was taken as the discharge capacity (mAh) of the nth cycle. The discharge capacity retention rate of the battery in the nth cycle is the ratio (%) of the discharge capacity in the nth cycle to the discharge capacity in the first cycle. In this example and comparative example, the discharge capacity retention rate after 100 cycles was evaluated.

[0309] <5. Evaluation Results>

[0310] Table 5 shows that the negative electrode slurries prepared in Examples 1-20 produced very little agglomeration. This indicates that the negative electrodes prepared in Examples 1-20 exhibited fewer cracks during the winding test, and the electrode active material layer showed high flexibility. The negative electrode active material layer of the negative electrodes prepared in Examples 1-20 also showed high peel strength relative to the current collector. This demonstrates that the lithium-ion secondary batteries prepared in Examples 1-20 exhibited high discharge capacity retention, i.e., good cycle characteristics, as the batteries were used.

[0311] In Comparative Example 1, a negative electrode slurry was prepared using a copolymer CP1 that does not have amide bonds. The negative electrode slurry prepared in Comparative Example 1 contained agglomerates. The negative electrode slurry prepared in Comparative Example 1 could not be coated flatly relative to the current collector, and therefore could not produce an evaluable negative electrode or battery.

[0312] In Comparative Example 2, a copolymer CP2 containing excess amide bonds was used to prepare a negative electrode slurry, a negative electrode, and a lithium-ion secondary battery. The electrode slurry prepared in Comparative Example 2 contained agglomerates. The negative electrode active material layer slipped off during a winding test in Comparative Example 2. Furthermore, in Comparative Example 2, the peel strength of the negative electrode active material layer relative to the current collector was low. The lithium-ion secondary battery prepared in Comparative Example 2 exhibited low discharge capacity retention.

[0313] In Comparative Example 3, a copolymer CP3 without substituent (c) was used to prepare a negative electrode slurry, a negative electrode, and a lithium-ion secondary battery. The negative electrode prepared in Comparative Example 3 exhibited numerous cracks in the negative electrode active material layer after a winding test, resulting in low flexibility. Furthermore, the peel strength of the negative electrode active material layer relative to the current collector was low in Comparative Example 3. The lithium-ion secondary battery prepared in Comparative Example 3 showed low discharge capacity retention.

[0314] In Comparative Example 4, a large amount of polyfunctional thiol compound (C) was used in an attempt to synthesize copolymer CP4 containing an excess of substituent (c), but the product gelled and could not be used to produce an evaluable negative electrode slurry.

[0315] In Comparative Example 5, a copolymer CP5, containing structural units derived from a tetrafunctional acrylate (tetramethylolpropane tetraacrylate) without substituent (c), was used to prepare a negative electrode slurry, a negative electrode, and a lithium-ion secondary battery. The negative electrode prepared in Comparative Example 5 exhibited numerous cracks in the negative electrode active material layer after a winding test, resulting in low flexibility. Furthermore, the peel strength of the negative electrode active material layer relative to the current collector was low in Comparative Example 5. The lithium-ion secondary battery prepared in Comparative Example 5 showed low discharge capacity retention.

[0316] Therefore, by using the copolymer of adhesive in this embodiment as an adhesive for the negative electrode of a non-aqueous battery, it was found that while ensuring sufficient adhesion between the negative electrode active materials in the negative electrode of a non-aqueous battery and between the negative electrode active materials and the current collector, flexibility was provided, resulting in good charge-discharge cycle characteristics of the battery.

[0317] In addition, these adhesives can also be used as adhesives for the positive electrode of non-aqueous batteries, and can be used to make batteries with good charge-discharge cycle characteristics while ensuring sufficient adhesion between the positive electrode active materials and between the positive electrode active materials and the current collector.

Claims

1. A non-aqueous secondary battery electrode adhesive, comprising a copolymer (P), characterized in that, The copolymer (P) has: A main chain consisting solely of bonds between carbon atoms. Substituents containing amide bonds, Substituents in salts containing carboxyl groups, and The substituent (c) represented by the following general formula (1) The substituent having an amide bond, the substituent having a carboxyl group, and the substituent (c) are respectively bonded to the main chain. The copolymer (P) contains amide bonds in an amount of 0.050 mmol / g or more and 5.0 mmol / g or less per 1g. The amount of carboxyl salt contained in each 1g of the copolymer (P) is more than 5.0 mmol / g and less than 12.0 mmol / g. The amount of the substituent (c) contained in each 1g of the copolymer (P) is 0.15 × 10⁻⁶. -2 mmol / g or higher and 8.0×10 - 2 Below mmol / g In general formula (1), R 31 It is a hydrocarbon group, R 32 For hydrogen atoms or methyl groups, m and n represent the groups with respect to R. 31 The number of substituents that are directly bound, where m is an integer greater than or equal to 0, n is an integer greater than or equal to 1, and m+n≥2.

2. The non-aqueous secondary battery electrode adhesive as described in claim 1, wherein R in the general formula (1) 31 It is composed of carbon atoms and hydrogen atoms.

3. The non-aqueous secondary battery electrode adhesive as described in claim 1 or 2, wherein in the general formula (1), R 31 It has multiple carbon atoms, and all the bonds between the carbon atoms are single bonds.

4. The non-aqueous secondary battery electrode adhesive as described in claim 1 or 2, wherein when the formula weight of the substituent (c) is set to Mc, Mc / (m+n)≤400.

5. The non-aqueous secondary battery electrode adhesive as described in claim 1 or 2, wherein the substituent (c) is derived from a polyfunctional thiol compound (C), wherein the polyfunctional thiol compound (C) has two or more thiol groups in one molecule.

6. The non-aqueous secondary battery electrode adhesive as described in claim 1 or 2, wherein the copolymer (P) further contains 0.50% by mass and 20.0% by mass of the structural unit (d) shown in general formula (2), In general formula (2), R 41 R 42 R 44 Each is independently an alkyl group having 1 or more hydrogen atoms and 5 or fewer carbon atoms, R 43 It is an alkyl group with 1 or more but less than 6 carbon atoms, R 43 The number of carbon atoms is greater than that of R 42 Many, j and k represent the number of structures connected in series within the corresponding parentheses, j is an integer greater than or equal to 1, k is an integer greater than or equal to 0, and j+k≥20.

7. The non-aqueous secondary battery electrode adhesive as described in claim 1 or 2, wherein the copolymer (P) further contains a structural unit (e) represented by the following general formula (3) in an amount of 0.030 mmol / g or more and 1.75 mmol / g or less per 1g of the copolymer (P). In general formula (3), R 51 R represents a hydrogen atom or a methyl group. 52 It is a substituent with an aromatic ring.

8. The non-aqueous secondary battery electrode adhesive as described in claim 1 or 2, wherein at least a portion of the amide bonds in the copolymer (P) are contained in the form of structural unit (a) represented by the following general formula (4), In general formula (4), R 11 R 12 Each can be used independently to represent an alkyl group having 1 or more hydrogen atoms and 5 or fewer carbon atoms.

9. The non-aqueous secondary battery electrode adhesive as described in claim 1 or 2, wherein in the copolymer (P), at least a portion of the salt of the carboxyl group is contained in the form of structural unit (b) as shown in the following general formula (5), In general formula (5), R 2 This represents a hydrogen atom or a methyl group, where X is a cation.

10. The non-aqueous secondary battery electrode adhesive as described in claim 1 or 2, characterized in that, The copolymer (P) has a weight-average molecular weight of 700,000 or more and 7.5 million or less.

11. A non-aqueous secondary battery electrode adhesive composition comprising the non-aqueous secondary battery electrode adhesive of claim 1 or 2 and an aqueous medium.

12. A non-aqueous secondary battery electrode, comprising a current collector and an electrode active material layer formed on the surface of the current collector. The electrode active material layer contains the binder and electrode active material for non-aqueous secondary battery electrodes as described in claim 1 or 2.

13. A non-aqueous secondary battery, characterized in that, It comprises a positive electrode, a negative electrode, and an electrolyte, wherein at least one of the positive electrode and the negative electrode is the non-aqueous secondary battery electrode as described in claim 12.

14. A method for manufacturing a non-aqueous secondary battery electrode adhesive, characterized in that, A polymerization process in which a monomer (M) having an olefinic unsaturated double bond is subjected to free radical polymerization in the presence of a polyfunctional thiol compound (C) having two or more thiol groups in one molecule. The monomer (M) contains a monomer (A) having an amide bond and a monomer (B) having a carboxyl group as a salt. When using the monomer (M), the polyfunctional thiol compound (C), the polymerization initiator, and the chain transfer agent, if the chain transfer agent is also considered as a polymerization component, then... The amount of monomer (A) contained in each 1g of the polymer component is 0.050 mmol / g or more and 5.0 mmol / g or less. The amount of monomer (B) contained in each 1g of the polymeric component is 5.0 mmol / g or more and 12.0 mmol / g or less. The amount of the polyfunctional thiol compound (C) contained in each 1g of the polymer component is 0.15 × 10⁻⁶. -2 mmol / g or higher and 8.0×10 -2 Below mmol / g.

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