Composition for electrode of nonaqueous electrolyte secondary battery, electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery

Abstract

To provide a composition for an electrode of a nonaqueous electrolyte secondary battery capable of effectively enhancing dispersibility of solid particles to a dispersion medium and forming an electrode active material layer excellent in oxidation resistance.SOLUTION: A composition for an electrode contains a polymer X and a dispersion medium, wherein the polymer X contains at least a constituent component (a) represented by any of the following: R11 and R21 represent hydrogen atoms or alkyl groups, R12 represents substituents containing a lactone-ring structure, and R22 and R3 represent substituents containing a lactone-ring structure or an aliphatic hydrocarbon-ring structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a composition for an electrode of a non-aqueous electrolyte secondary battery, an electrode for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery. [Background technology]

[0002] Non-aqueous electrolyte secondary batteries, typified by lithium-ion secondary batteries, have high energy density and excellent storage performance, low-temperature operation, etc., and are widely used in portable electronic devices such as mobile phones and laptop computers. Furthermore, larger batteries are being used in transportation equipment such as automobiles, and their use as storage devices for nighttime electricity and electricity generated by natural energy sources is also progressing.

[0003] The electrodes (positive and negative electrodes) of non-aqueous electrolyte secondary batteries generally have an electrode active material layer (positive electrode active material layer or negative electrode active material layer), which contains electrode active material particles capable of absorbing or releasing lithium ions during charge and discharge. The electrode active material layer is usually formed by forming a film using a slurry (composition) containing the constituent components of the electrode active material layer (electrode active material, conductive additive, etc.). With regard to improving the performance of non-aqueous electrolyte secondary batteries, studies have been conducted focusing on the electrode active material layer.

[0004] For example, Patent Document 1 discloses a carbon nanotube dispersant composition containing a copolymer including an alkyl(meth)acrylate or alkylacrylamide-based structural unit A and a (meth)acrylate-based structural unit B having an alkyleneoxy chain, and a solvent. Patent Document 1 also describes that by mixing this carbon nanotube dispersant composition with carbon nanotubes, which are a conductive material, and subjecting the mixture to a dispersion treatment, it is possible to prepare a conductive material dispersion liquid in which carbon nanotubes are well dispersible, and that by using a positive electrode paste obtained by mixing this conductive material dispersion liquid with a positive electrode active material, a low-resistance positive electrode composite layer can be obtained.

[0005] Furthermore, Patent Document 2 states: Contains a polymer (A) and a liquid medium (B), When the total amount of repeating units contained in the polymer (A) is taken as 100 mass %, the polymer (A) 50 to 99 mass% of repeating units (a1) derived from a conjugated diene compound; 1 to 19% by mass of repeating units (a2) derived from an α,β-unsaturated nitrile compound; Contains A binder composition for an electricity storage device, wherein the polymer (A) has a weight average molecular weight (Mw) of 100,000 to 2,000,000. Patent Document 2 discloses that a binder composition containing the polymer (A) and N-methyl-2-pyrrolidone (NMP) was prepared in the examples. Patent Document 2 also describes that when this binder composition is mixed with a positive electrode active material to obtain a slurry, and this slurry is applied and dried to form a positive electrode active material layer, coating defects can be suppressed, this positive electrode active material layer has excellent adhesion to the current collector, and the resulting secondary battery is less likely to increase in resistance and has improved cycle characteristics. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2020 / 208800 [Patent Document 2] International Publication No. 2024 / 009866 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, the electrode active material layer is prepared by preparing a slurry (electrode slurry) in which solid particles (e.g., electrode active material, conductive additive, etc.) are dispersed in a dispersion medium, and then forming the resulting electrode active material layer into a film. In this process, it is necessary to control the properties of the electrode slurry from various angles to improve production efficiency, the resulting battery performance, etc. For example, to improve the handleability of the electrode slurry and form a uniform and precise electrode active material layer, the electrode slurry is required to exhibit an appropriately low viscosity (excellent dispersibility). The dispersibility of solid particles can be improved by blending a polymer (polymer dispersant) such as that described in Patent Document 1 into the positive electrode slurry. To improve dispersibility, it is particularly important to improve the dispersibility of the conductive additive, which has a small particle diameter, a large specific surface area, and is prone to aggregation. The technology described in Patent Document 1 also aims to improve the dispersibility of carbon nanotubes, which function as conductive additives in the electrode active material layer. However, as a result of further investigations, the inventors have found that an electrode active material layer containing a polymer dispersant as described in Patent Document 1 does not have sufficient oxidation resistance when incorporated into a battery and operated, and as a result, the discharge capacity of the resulting secondary battery is likely to decrease during large current charging and discharging.

[0008] An object of the present invention is to provide an electrode composition for a nonaqueous electrolyte secondary battery, which, when used to prepare an electrode slurry containing solid particles such as a conductive additive, can effectively improve the dispersibility of the solid particles in a dispersion medium and enable the formation of an electrode active material layer with excellent oxidation resistance when used in preparing an electrode slurry containing solid particles such as a conductive additive. Another object of the present invention is to provide an electrode formed using this electrode composition, and a nonaqueous electrolyte secondary battery incorporating this electrode. [Means for solving the problem]

[0009] The above-mentioned problems of the present invention have been solved by the following means. [1] A composition for an electrode containing polymer X and a dispersion medium, The composition for an electrode of a non-aqueous electrolyte secondary battery, wherein the polymer X contains at least a component (a) represented by any one of the following (i) to (iii): [ka] In the above formula, R 11 and R 21 represents a hydrogen atom or an alkyl group. R 12 represents a substituent containing a lactone ring structure. R 22 and R 3 represents a substituent containing a lactone ring structure or an aliphatic hydrocarbon ring structure. * indicates a binding site for incorporation into the polymer. [2] The electrode composition according to [1], wherein the content of the component (a) in the polymer X is 20% by mass or more. [3] The composition for an electrode according to [2], wherein the polymer X contains a component (b) different from the component (a), and the component (b) has at least one of an aromatic hydrocarbon group and an acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms. [4] The composition for an electrode according to [3], wherein the polymer X has a weight average molecular weight of 1,000 to 30,000. [5] The electrode composition according to [4], wherein the dispersion medium is an organic solvent. [6] The electrode composition according to [5], which contains a conductive additive. [7] The electrode composition according to [6], which contains an electrode active material. [8] The electrode composition according to [7], wherein the electrode active material is a positive electrode active material. [9] An electrode for a non-aqueous electrolyte secondary battery, formed using the electrode composition according to [7].

[10] [9] A non-aqueous electrolyte secondary battery having the electrode for a non-aqueous electrolyte secondary battery according to [9] as an electrode.

[0010] In the description of the present invention, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In the present invention, "nonaqueous electrolyte" refers to an electrolyte that is substantially free of water. That is, the "nonaqueous electrolyte" may contain a small amount of water as long as the effect of the present invention is not impaired. In the present invention, the "nonaqueous electrolyte" has a water concentration of 200 ppm (by mass) or less, preferably 100 ppm or less, and more preferably 20 ppm or less. Note that it is practically difficult to make a nonaqueous electrolyte completely anhydrous, and it usually contains 1 ppm or more of water. In the present invention, the term "non-aqueous solvent" also refers to a solvent that is substantially free of water. That is, the "non-aqueous solvent" may contain a small amount of water as long as the effect of the present invention is not impaired. In the present invention, the "non-aqueous solvent" has a water concentration of 200 ppm (by mass) or less, preferably 100 ppm or less, and more preferably 20 ppm or less. Note that it is practically difficult to make a non-aqueous solvent completely anhydrous, and it usually contains 1 ppm or more of water. [Effects of the Invention]

[0011] The electrode composition for a non-aqueous electrolyte secondary battery of the present invention can efficiently form an electrode active material layer and can improve the oxidation resistance of the obtained electrode active material layer in the battery. By incorporating the electrode of the present invention into a non-aqueous electrolyte secondary battery, the oxidation resistance can be improved. The non-aqueous electrolyte secondary battery of the present invention has excellent oxidation resistance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a longitudinal sectional view showing a schematic basic layer structure of an embodiment of a secondary battery according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Although preferred embodiments of the present invention will be described, the present invention is not limited to these embodiments except as defined in the present invention.

[0014] [Composition for electrode] The electrode composition for a non-aqueous electrolyte secondary battery of the present invention (hereinafter also referred to as "electrode composition of the present invention") contains a polymer X and a dispersion medium. This polymer X contains at least a component (a), and this component (a) is represented by any one of the following (i) to (iii):

[0015] [ka]

[0016] In the above formula, R 11 and R 21 represents a hydrogen atom or an alkyl group. R 12 represents a substituent containing a lactone ring structure. R 22 and R 3 represents a substituent containing a lactone ring structure or an aliphatic hydrocarbon ring structure. * indicates a binding site for incorporation into the polymer.

[0017] The electrode composition of the present invention can be suitably used as a material for forming an electrode active material layer that constitutes a non-aqueous electrolyte secondary battery. The electrode composition of the present invention can contain a conductive additive in addition to the polymer X and the dispersion medium. It may also contain an electrode active material. Regarding the electrode composition of the present invention, a composition containing polymer X and a dispersion medium but not containing either an electrode active material or a conductive additive is referred to as a first embodiment. A composition containing polymer X, a dispersion medium, and an electrode active material but not containing a conductive additive is referred to as a second embodiment. A composition containing polymer X, a dispersion medium, and a conductive additive but not containing an electrode active material is referred to as a third embodiment. A composition containing polymer X, a dispersion medium, an electrode active material, and a conductive additive is referred to as a fourth embodiment.

[0018] The electrode composition of the first embodiment is usually a polymer solution in which polymer X is dissolved in a dispersion medium, and can be used to enhance the dispersibility of solid particles when mixed with solid particles such as a conductive additive, an electrode active material, etc. to prepare a slurry. That is, the electrode composition of the first embodiment can be used to prepare the electrode composition of the second, third, or fourth embodiment. The electrode composition of the second embodiment is a composition in which an electrode active material is dispersed in a polymer solution. The electrode composition of the second embodiment may be further mixed with a conductive additive (i.e., a fourth embodiment of the electrode composition) and used to form an electrode active material layer. The electrode composition of the third embodiment is a composition in which a conductive additive is dispersed in a polymer solution, and can be used to form an electrode active material layer by further mixing the electrode composition of the third embodiment with an electrode active material (i.e., preparing an electrode composition of the fourth embodiment). The electrode composition of the fourth form is a composition in which an electrode active material and a conductive assistant are dispersed in a polymer solution, and can be used to form an electrode active material layer as is or after dilution, concentration, etc.

[0019] In the above-described first to fourth preferred aspects of the present invention, the electrode composition of the present invention can be used to prepare an electrode slurry for a general nonaqueous electrolyte secondary battery (a nonaqueous electrolyte secondary battery that is not a quasi-solid secondary battery), and can also be used as an electrode slurry itself for a general nonaqueous electrolyte secondary battery. The electrode composition of the present invention may further contain an electrolyte, and this form of electrode composition can be used to prepare an electrode slurry for a quasi-solid secondary battery, or can be used as the electrode slurry itself for a quasi-solid secondary battery. The electrode slurry for a quasi-solid secondary battery differs from electrode compositions for general non-aqueous electrolytes in that it contains an electrolyte (i.e., it contains an electrolyte solution in which an electrolyte is added to a dispersion medium). Quasi-solid secondary batteries themselves are known, and reference can be made to, for example, JP 2017-147222 A and WO 2023 / 106214 A.

[0020] The polymer X contained in the electrode composition of the present invention is thought to function primarily as a dispersant for solid particles (electrode active material, conductive additive, etc.) in the dispersion medium in the electrode composition. In particular, the conductive additive can be dispersed efficiently. Typically, the conductive additive has poor dispersibility due to its large specific surface area and small particle diameter relative to the electrode active material. In the electrode composition of the present invention, the component (a) of the polymer X improves steric repulsion and suppresses aggregation between solid particles. As a result, the solid particles can be efficiently dispersed in the dispersion medium. Furthermore, in the electrode composition of the present invention, the component (a) is contained in the polymer X, making the polymer X less susceptible to oxidation. As a result, by forming an electrode active material layer using the electrode composition of the present invention, the oxidation resistance of the electrode during battery operation can be improved.

[0021] Each component constituting the electrode composition of the present invention will now be described in more detail.

[0022] <Polymer X> In the electrode composition of the present invention, the polymer X is usually dissolved in a dispersion medium. The electrode composition of the present invention contains at least one or more constituents (a). The constituent (a) contained in the polymer X mainly functions to enhance compatibility with the dispersion medium. It is also preferable that the constituent (a) has the ability to adsorb to solid particles. The specific chemical structure of the constituent (a) will be described later. In the present invention, polymer X may be either a homopolymer or a copolymer, preferably a copolymer, as long as it contains component (a). When it is a copolymer, the polymerization form may be either random or block. Polymer X is a so-called chain polymerization polymer in which component (a) is incorporated into the main chain of the polymer via * in structures (i) to (iii). The electrode composition of the present invention may contain, in addition to polymer X, a polymer other than polymer X.

[0023] - Component (a) - The structure of the component (a) is represented by any one of the following (i) to (iii).

[0024] [ka]

[0025] In the above (i) to (iii), R 11 and R 21 represents a hydrogen atom or an alkyl group. 11 and R 21 The alkyl group that can be taken as R is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, further preferably methyl or ethyl, and even more preferably methyl. 11 and R 21 When R is an alkyl group, a heteroatom (e.g., an oxygen atom, a sulfur atom, or a nitrogen atom) may be incorporated in the carbon chain of the alkyl group. 11 and R 21 When R is an alkyl group, the hydrogen atoms of the alkyl group may be further substituted with halogen atoms. 11 and R 21 is preferably a hydrogen atom, methyl or methoxymethyl, more preferably a hydrogen atom.

[0026] R 12 represents a substituent containing a lactone ring structure. R 22 and R 3 represents a substituent containing a lactone ring structure or an aliphatic hydrocarbon ring structure.

[0027] The lactone ring structure is preferably a 4- to 7-membered lactone ring structure, more preferably a 5- or 6-membered lactone ring structure, and even more preferably a 5-membered lactone ring structure. When referring to a Z-membered ring (where Z represents a number), Z refers to the number of ring-constituting atoms that directly constitute the ring. Therefore, the oxygen atom of the carbonyl group in the lactone ring structure (oxygen atom bonded to a ring-constituting carbon atom) is not a ring-constituting atom. The lactone ring structure may be a structure in which another ring structure is fused to the 4- to 7-membered lactone ring structure in the form of a bicyclo structure or a spiro structure. The lactone ring structure is preferably not a fused ring structure. The lactone ring structure may have a substituent, for example, an alkyl group having 1 to 4 carbon atoms. R 12 , R 22 , and R 3 Examples of the lactone ring structure that may be included include a γ-butyrolactone ring (five-membered ring), a mevalonolactone ring (six-membered ring), and a 5,3-bicyclo[2.2.1]heptanecarbolactone ring (a structure in which a bicyclo[2.2.1]heptane ring is fused to a five-membered lactone ring). The substituent containing a lactone ring structure may have a lactone ring structure, and may be a ring group obtained by removing one hydrogen atom from the lactone ring structure, or may be a group having a structure in which the lactone ring structure is bonded to a linking group. Examples of the linking group include aliphatic hydrocarbon groups, which may have an oxygen atom. More specifically, the linking group is preferably an alkylene group, -O-, -COO-, -OCO-, -CO-, or a divalent linking group formed by combining these.

[0028] The aliphatic hydrocarbon ring structure may be a cycloalkane structure or a cycloalkene structure, with a cycloalkane structure being preferred. The aliphatic hydrocarbon ring structure may be a monocyclic structure or a fused ring structure in which monocyclic aliphatic hydrocarbon rings are fused together. For example, it may be a cyclocyclic, dicyclocyclic, or tricyclocyclic structure. The aliphatic hydrocarbon ring structure is preferably a monocyclic structure. The aliphatic hydrocarbon ring structure preferably has 4 to 20 carbon atoms, more preferably 4 to 15 carbon atoms, and even more preferably 5 to 10 carbon atoms. The aliphatic hydrocarbon ring structure may have a substituent. Examples of the substituent that the aliphatic hydrocarbon ring structure may have include an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, and a halogen atom (for example, a fluorine atom, a chlorine atom, or a bromine atom). It is preferable that the aliphatic hydrocarbon ring structure has no substituent. R 12 , R 22 , and R 3 Examples of the aliphatic hydrocarbon ring structure that may be contained include cyclopentane, cycloheptane, and adamantane. The substituent containing the aliphatic hydrocarbon ring structure may have an aliphatic hydrocarbon ring structure, and may be a ring group obtained by removing one hydrogen atom from the aliphatic hydrocarbon ring structure, or may be a structure in which the aliphatic hydrocarbon ring structure is bonded to a linking group. Examples of the linking group include an aliphatic hydrocarbon group, and this aliphatic hydrocarbon group may have an oxygen atom. More specifically, the linking group is preferably an alkylene group, -O-, -COO-, -OCO-, -CO-, or a divalent linking group formed by combining these.

[0029] R 12 is preferably a ring group obtained by removing one hydrogen atom from a lactone ring structure that is not a fused ring, or a substituent having a structure in which a lactone ring structure of a fused ring structure is bonded to a linking group, more preferably a ring group obtained by removing one hydrogen atom from a lactone ring structure that is not a fused ring, and even more preferably a ring group obtained by removing one hydrogen atom from a mevalonolactone ring structure, or a ring group obtained by removing one hydrogen atom from γ-butyrolactone. R 22 is preferably a cyclic group obtained by removing one hydrogen atom from an aliphatic hydrocarbon ring structure, more preferably a cyclic group obtained by removing one hydrogen atom from an aliphatic hydrocarbon ring having 5 to 10 carbon atoms, more preferably a cyclic group obtained by removing one hydrogen atom from a monocyclic aliphatic hydrocarbon ring having 5 to 7 carbon atoms, and even more preferably cyclopentyl. R 3 is preferably a ring group obtained by removing one hydrogen atom from an aliphatic hydrocarbon ring structure, and more preferably cyclohexyl.

[0030] The substituent containing the lactone ring structure or the aliphatic hydrocarbon ring structure preferably has a chemical formula weight of 40-400, more preferably 40-250, even more preferably 50-200, and even more preferably 70-150.

[0031] The structure of the component (a) is preferably (i) or (ii), and more preferably (ii).

[0032] Regarding the structures represented by the formulas (i) to (iii) above, preferred specific examples of the monomers that lead to each structure are shown below, but the present invention is not limited to these specific examples.

[0033] Monomers leading to the constituents represented by (i)

[0034] [ka]

[0035] Monomers leading to the constituents represented by (ii)

[0036] [ka]

[0037] Monomers leading to the constituents represented by (iii)

[0038] [ka]

[0039] When polymer X is a copolymer, from the viewpoint of improving dispersibility and oxidation resistance, polymer X preferably contains 20% by mass or more of component (a), more preferably 30% by mass or more, and even more preferably 40% by mass or more of component (a). There is no particular upper limit, and it can be 80% by mass. Therefore, the content of component (a) in polymer X is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40 to 60% by mass.

[0040] - Component (b) - In addition to the component (a), the polymer X may contain a component (b) different from the component (a). The component (b) preferably contains at least one of an aromatic hydrocarbon group and an acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms. The aromatic hydrocarbon group and the acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms contained in component (b) are thought to function mainly as an adsorptive group for solid particles.

[0041] The acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms that can be contained in component (b) preferably has 4 to 50 carbon atoms, more preferably 4 to 40 carbon atoms, even more preferably 10 to 40 carbon atoms, even more preferably 15 to 35 carbon atoms, and even more preferably 15 to 30 carbon atoms. The acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms that can be contained in component (b) may be linear or branched. The acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms that can be contained in component (b) may be unsubstituted or may have a substituent. A heteroatom may be incorporated into the carbon chain of the acyclic aliphatic hydrocarbon group, and in this case, an oxygen atom and / or a nitrogen atom is preferably incorporated. More specifically, the acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms may have a structure in which at least one of -O-, -COO-, -OCO-, -CO-, and -NH- is incorporated into the carbon chain. The aromatic hydrocarbon group that can be contained in component (b) may be a single ring or a fused ring. The aromatic hydrocarbon group that can be contained in component (b) preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms. The aromatic hydrocarbon group that can be contained in component (b) is preferably a phenyl group or a naphthyl group, more preferably a phenyl group. Component (b) may contain both an aromatic hydrocarbon group and a non-cyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms. For example, a non-cyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms may have an aromatic hydrocarbon group as a substituent, or an aromatic hydrocarbon group may have a non-cyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms as a substituent. When a non-cyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms has an aromatic hydrocarbon group as a substituent, the non-cyclic aliphatic hydrocarbon group preferably has 2 to 30 carbon atoms, more preferably 2 to 10 carbon atoms, and even more preferably 2 to 5 carbon atoms. Component (b) preferably has an aromatic hydrocarbon group, an alkyl group having 4 to 50 carbon atoms, or a group in which an alkyl group having 2 to 5 carbon atoms has an aromatic hydrocarbon group as a substituent, more preferably a phenyl group, an alkyl group having 10 to 40 carbon atoms, or a group in which an alkyl group having 2 to 5 carbon atoms has an aromatic hydrocarbon group as a substituent, and even more preferably an alkyl group having 15 to 30 carbon atoms or a benzyl group.

[0042] The constituent component (b) is not particularly limited as long as it has at least one of the above aromatic hydrocarbon group and acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms. The constituent component (b) is preferably a constituent component derived from a compound in which at least one of the above aromatic hydrocarbon group and acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms is introduced into a (meth)acrylic acid ester compound, a (meth)acrylamide component, or a maleimide component. More specifically, the ... compound in which R 12 , R 22 , and R 3 The groups corresponding to R 13 , R 23 , R 33 In the structure, R 13 , R 23 and R 33However, the component (b) may have at least one of the aromatic hydrocarbon group and the acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms. The component (b) may also be a component derived from a compound (for example, styrene) in which a vinyl group is bonded to at least one of the aromatic hydrocarbon group and the acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms.

[0043] When polymer X is a copolymer, from the viewpoint of improving dispersibility and oxidation resistance, polymer X preferably contains 20% by mass or more of component (b), more preferably 30% by mass or more, and even more preferably 40% by mass or more. The upper limit is not particularly limited and can be, for example, 80% by mass. Therefore, the content of component (b) in polymer X is preferably 20 to 80% by mass, more preferably 30 to 70% by mass, and even more preferably 40 to 60% by mass.

[0044] Preferred specific examples of the monomer from which component (b) is derived are shown below.

[0045] Monomers that lead to component (b)

[0046] [ka]

[0047] - Other components - The polymer X may contain components other than the above-mentioned component (a) and component (b) (“other components”), as long as the effects of the present invention are not impaired. When polymer X contains other constituent components, the content of the other constituent components is preferably 20% by mass or less, more preferably 15% by mass or less, and more preferably 10% by mass or less.

[0048] The weight average molecular weight (Mw) of the polymer X is not particularly limited, and is preferably 1,000 to 80,000, more preferably 1,000 to 50,000, even more preferably 1,000 to 30,000, still more preferably 2,000 to 20,000, still more preferably 2,000 to 15,000, still more preferably 2,000 to 12,000, still more preferably 3,000 to 10,000, still more preferably 3,000 to 8,000, and still more preferably 3,000 to 7,000.

[0049] -- Measurement of weight average molecular weight -- In the present invention, the Mw of polymer X is measured by gel permeation chromatography (GPC). Mw is calculated as polyethylene oxide. In principle, Mw is measured by the following method. However, depending on the type of polymer, an appropriate eluent (carrier) may be selected and used. Measuring instrument: HLC-8320GPC (product name, manufactured by Tosoh Corporation) Column: TOSOH TSKgel guard column SuperHZ-L, Super HZM-H, Super HZ4000, Super HZ2000 (product names, manufactured by Tosoh Corporation) Carrier: Tetrahydrofuran solution Measurement temperature: 40℃ Carrier flow rate: 0.35 ml / min Sample concentration: 0.2% by mass Detector: RI (refractive index) detector

[0050] Polymer X can be synthesized by selecting raw materials using known methods. For example, a monomer from which component (a) is derived, a monomer from which component (b) is derived, and monomers from which other components are derived can be dissolved in a dispersion medium together with a polymerization initiator, and the resulting solution can be added dropwise to a heated dispersion medium to cause polymerization. In this way, a polymer X solution (the first embodiment of the electrode composition of the present invention) in which polymer X is dissolved in the dispersion medium can be obtained. The polymer X solution can be used as is to prepare the second to fourth embodiments of the electrode composition of the present invention.

[0051] In the first embodiment (polymer solution) of the composition for an electrode of the present invention, the content of polymer X is not particularly limited, and is preferably 1 to 70 mass % of the composition (total of polymer X and dispersion medium), more preferably 3 to 50 mass %, and even more preferably 5 to 40 mass %. In the second embodiment of the electrode composition of the present invention, the content of polymer X is not particularly limited, and is preferably 0.001 to 10 mass %, more preferably 0.005 to 5 mass %, and even more preferably 0.01 to 1 mass %, of the composition (total of polymer X, dispersion medium, and electrode active material). In the third embodiment of the electrode composition (conductive additive slurry) of the present invention, the content of polymer X is not particularly limited, and is preferably 0.01 to 69 mass %, more preferably 0.1 to 57 mass %, and even more preferably 0.5 to 45 mass %, of the composition (total of polymer X, dispersion medium, and conductive additive). In the fourth embodiment of the electrode composition (electrode slurry) of the present invention, the content of polymer X is not particularly limited, and is preferably 0.001 to 10 mass %, more preferably 0.005 to 5 mass %, and even more preferably 0.01 to 1 mass %, of the composition (total of polymer X, dispersion medium, electrode active material, and conductive additive).

[0052] In the second embodiment of the electrode composition of the present invention, the content of polymer X in the total of polymer X and the electrode active material is preferably 0.01 to 10.00 mass%, more preferably 0.05 to 5.00 mass%, and even more preferably 0.10 to 1.00 mass%. In the third embodiment of the electrode composition of the present invention (conductive assistant slurry), the content of polymer X in the total of polymer X and conductive assistant is preferably 0.1 to 90 mass%, more preferably 1 to 80 mass%, and even more preferably 5 to 70 mass%. In the fourth embodiment of the electrode composition (electrode slurry) of the present invention, the content of polymer X in the total of polymer X, electrode active material, and conductive assistant is preferably 0.01 to 10 mass%, more preferably 0.05 to 5 mass%, and even more preferably 0.10 to 1 mass%.

[0053] <Dispersion medium> The electrode composition of the present invention contains a dispersion medium, which functions as a solvent or dispersion medium for the polymer or solid particles in the electrode composition.

[0054] The SP value of the dispersion medium is 14 to 30 MPa. 1 / 2 is preferable, and 16 to 28 MPa 1 / 2 More preferably, 18 to 26 MPa 1 / 2 More preferably, 20 to 24 MPa 1 / 2 is more preferable. The SP value is the SP value obtained by HSPiP software (Pirika.com, ver. 5), and can be determined by inputting the Smiles formula of the structure and calculating the Hildebrand SP value (δTot).

[0055] The dispersion medium may be, for example, water or an organic solvent (preferably a non-aqueous solvent). The organic solvent is preferably an aprotic organic solvent, and more preferably an aprotic organic solvent having 2 to 10 carbon atoms. Such organic solvents are preferably non-aqueous solvents containing a heteroatom (such as an oxygen atom, a nitrogen atom, a sulfur atom, or a phosphorus atom), and examples thereof include linear or cyclic carbonate compounds, lactone compounds, linear or cyclic ether compounds, ester compounds, nitrile compounds, amide compounds, oxazolidinone compounds, nitro compounds, linear or cyclic sulfone or sulfoxide compounds, phosphate ester compounds, and cyclic ketone compounds. Among these, compounds having an ether bond, a carbonyl bond, an ester bond or a carbonate bond, and cyclic ketone compounds are preferred. These compounds may have a substituent. The organic solvent is preferably an alkylpyrrolidone compound, more preferably an N-alkylpyrrolidone compound.

[0056] Specific preferred examples of the organic solvent include ethylene carbonate, fluorinated ethylene carbonate, vinylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, γ-butyrolactone, γ-valerolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane, methyl acetate, and ethyl acetate. Examples of suitable solvents include methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate, ethyl trimethylacetate, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, N,N-dimethylformamide, N-methylpyrrolidone (NMP), N-ethylpyrrolidone, N-methyloxazolidinone, N,N'-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate, dimethyl sulfoxide or dimethyl sulfoxide phosphate, cyclohexanone, etc. These may be used alone or in combination of two or more. However, the organic solvents used in the present invention are not limited to these. In the present invention, the dispersion medium is preferably N-methylpyrrolidone (NMP), N-ethylpyrrolidone or cyclohexanone, and more preferably NMP.

[0057] In the first embodiment (polymer solution) of the composition for an electrode of the present invention, the content of the dispersion medium is not particularly limited, and is preferably 30 to 99 mass %, more preferably 50 to 97 mass %, and even more preferably 60 to 95 mass % of the composition (total of polymer X and dispersion medium). In the second embodiment of the electrode composition of the present invention, the content of the dispersion medium is not particularly limited, and is preferably 5 to 50 mass %, more preferably 10 to 40 mass %, and even more preferably 15 to 29 mass % in the composition. In the third embodiment of the electrode composition of the present invention (conductive assistant slurry), the content of the dispersion medium is not particularly limited, and is preferably 30 to 95 mass %, more preferably 40 to 90 mass %, and even more preferably 50 to 80 mass % in the composition. In the fourth embodiment of the electrode composition (electrode slurry) of the present invention, the content of the dispersion medium is not particularly limited, and is preferably 5 to 50 mass %, more preferably 10 to 40 mass %, and even more preferably 15 to 30 mass % in the composition.

[0058] <Electrode active material> The electrode active material may be a positive electrode active material or a negative electrode active material, with a positive electrode active material being more preferred. When the electrode composition of the present invention contains a positive electrode active material, the electrode composition of the present invention can be used to form a positive electrode active material layer. When the electrode composition of the present invention contains a negative electrode active material, the electrode composition of the present invention can be used to form a negative electrode active material layer. The electrode composition of the present invention preferably contains a positive electrode active material.

[0059] - Cathode active material - The electrode composition of the present invention can contain a positive electrode active material. The positive electrode active material is preferably one that can reversibly insert and release lithium ions. There are no particular limitations on the material, and examples include transition metal oxides, organic substances, sulfur, and other substances that can be combined with Li, as well as sulfur-metal composites. Among these, it is preferable to use a lithium-containing transition metal oxide as the positive electrode active material, and the transition metal element M a A lithium-containing transition metal oxide containing Co or Ni is more preferred. In addition, the lithium-containing transition metal oxide may further contain the element M. b (Elements of Group 1 (Ia) of the periodic table other than lithium, elements of Group 2 (IIa), Al, Ga, In, Ge, Sn, Pb, Sb, Bi, Si, P, B, etc.) may be mixed. The amount of the mixed element is determined by the following formula: a The amount of Li / M is preferably 0 to 30 mol% relative to the amount of Li (100 mol%). aMore preferably, the compounds are synthesized by mixing them so that the molar ratio is 0.3 to 2.2. Specific examples of lithium-containing transition metal oxides include (MA) lithium-containing transition metal oxides having a layered rock salt structure, (MB) lithium-containing transition metal oxides having a spinel structure, (MC) lithium-containing transition metal phosphate compounds, (MD) lithium-containing transition metal halide phosphate compounds, and (ME) lithium-containing transition metal silicate compounds.

[0060] (MA) Specific examples of lithium-containing transition metal oxides with a layered rock salt structure include LiCoO2 (lithium cobalt oxide [LCO]), LiNi2O2 (lithium nickel oxide), and LiNi 0.85 Co 0.10 Al 0.05 O2 (nickel cobalt lithium aluminate [NCA]), LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (lithium nickel manganese cobalt oxide [NMC]) and LiNi 0.5 Mn 0.5 O2 (lithium manganese nickel oxide). (MB) Specific examples of lithium-containing transition metal oxides having a spinel structure include LiMn2O4 (LMO), LiCoMnO4, Li2FeMn3O8, Li2CuMn3O8, Li2CrMn3O8, and Li2NiMn3O8. (MC) Examples of lithium-containing transition metal phosphate compounds include olivine-type iron phosphates such as LiFePO4 and Li3Fe2(PO4)3, iron pyrophosphates such as LiFeP2O7, cobalt phosphates such as LiCoPO4, and monoclinic Nasicon-type vanadium phosphates such as Li3V2(PO4)3 (lithium vanadium phosphate). (MD) Examples of lithium-containing transition metal halide phosphate compounds include iron fluorophosphates such as Li2FePO4F, manganese fluorophosphates such as Li2MnPO4F, and cobalt fluorophosphates such as Li2CoPO4F. (ME) Examples of lithium-containing transition metal silicate compounds include Li2FeSiO4, Li2MnSiO4, and Li2CoSiO4. In the present invention, the positive electrode active material is preferably a lithium-containing transition metal oxide having an (MA) layered rock salt structure, and more preferably LiCoO2. In the present invention, since the polymer X has high oxidation resistance, it is suitable for use in a positive electrode active material having a high redox potential. From this viewpoint, the positive electrode active material is preferably LiCoO2 and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and the like are preferred.

[0061] The shape of the positive electrode active material is not particularly limited, but a particulate shape is preferred. The average particle size (average equivalent spherical particle size) of the positive electrode active material is not particularly limited and can be, for example, 0.1 to 50 μm, preferably 0.2 to 30 μm, more preferably 0.5 to 20 μm, and even more preferably 0.8 to 10 μm. The positive electrode active material can be made to have a predetermined particle size by using a conventional grinder or classifier. The positive electrode active material obtained by the firing method may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent.

[0062] When a commercially available positive electrode active material is used, the average particle size of the positive electrode active material is the value listed in the manufacturer's catalog. When information on the average particle size from the manufacturer is unavailable or when a synthesized positive electrode active material is used, the positive electrode active material is dispersed in water and measured using a laser diffraction / scattering particle size distribution analyzer (e.g., HORIBA Particle LA-960V2), and the particle size value (volume-based median diameter D50 in water) obtained is used. This also applies to the average particle size of solid particles other than the positive electrode active material.

[0063] The chemical formula of the compound obtained by the above calcination method can be measured by inductively coupled plasma (ICP) emission spectroscopy, or simply calculated from the difference in mass of the powder before and after calcination.

[0064] The surface of the positive electrode active material may be coated with an oxide such as another metal oxide, a carbon-based material, etc. These surface coating layers can function as an interface resistance stabilizing layer. Examples of surface coating materials include metal oxides containing Ti, Nb, Ta, W, Zr, Al, Si, or Li. Specific examples include titanate spinel, tantalum-based oxides, niobium-based oxides, and lithium niobate-based compounds, such as Li4Ti5O 12 , Li2Ti2O5, LiTaO3, LiNbO3, LiAlO2, Li2ZrO3, Li2WO4, Li2TiO3, Li2B4O7, Li3PO4, Li2MoO4, Li3BO3, LiBO2, Li2CO3, Li2SiO3, SiO2, TiO2, ZrO2, Al2O3, BO3, and Li3AlF6. Carbon-based materials such as C, SiC, and SiOC (carbon-doped silicon oxide) can also be used as surface coating materials.

[0065] The positive electrode active material is preferably surface-coated with a carbonaceous material in order to increase the electronic conductivity to a desired level. In this case, the positive electrode active material is preferably surface-coated with carbon (C). The carbon surface coating can be formed by baking the positive electrode active material in the presence of an additive (organic substance) that serves as a carbon source. Examples of the additive that can be used include styrene-maleic anhydride copolymer, polystyrene, and polycarbonate.

[0066] The surface of the positive electrode active material may be treated with sulfur or phosphorus. Furthermore, the particle surfaces of the positive electrode active material may be subjected to a surface treatment with actinic rays or an active gas (plasma, etc.) before or after the above surface coating.

[0067] The positive electrode active materials may be used alone or in combination of two or more.

[0068] - Anode active material - The negative electrode active material is preferably one that can reversibly absorb and release lithium ions. The material is not particularly limited as long as it has the above properties, and examples thereof include carbonaceous materials, silicon-based materials, metal oxides, metal composite oxides, lithium alone, lithium alloys, and negative electrode active materials that can form alloys with lithium. Among these, carbonaceous materials and silicon-based materials are preferably used from the viewpoint of reliability.

[0069] The carbonaceous material used as the negative electrode active material is a material essentially composed of carbon. Examples include carbon black such as petroleum pitch, graphite (natural graphite, artificial graphite such as vapor-grown graphite, etc.), and carbonaceous materials obtained by calcining various synthetic resins such as PAN (polyacrylonitrile)-based resins and furfuryl alcohol resins. Other examples include various carbon fibers such as PAN-based carbon fiber, cellulose-based carbon fiber, pitch-based carbon fiber, vapor-grown carbon fiber, dehydrated PVA (polyvinyl alcohol)-based carbon fiber, lignin carbon fiber, glassy carbon fiber, and activated carbon fiber; mesophase microspheres; graphite whiskers; and tabular graphite.

[0070] The metal oxides and metal composite oxides used as the negative electrode active material are not particularly limited as long as they are oxides capable of absorbing and releasing lithium, and amorphous oxides are preferred, with chalcogenides being preferred as reaction products between metal elements and elements of Group 16 of the periodic table. The term "amorphous" as used herein refers to an oxide having a broad scattering band with a peak in the 2θ range of 20° to 40° in an X-ray diffraction method using CuKα radiation, and may also have crystalline diffraction lines. Among the compounds consisting of the amorphous oxides and chalcogenides, amorphous oxides and chalcogenides of metalloid elements are more preferred, and oxides or chalcogenides consisting of one or a combination of two or more of the elements of Groups 13 (IIIB) to 15 (VB) of the Periodic Table, Al, Ga, Si, Sn, Ge, Pb, Sb, and Bi are particularly preferred. Specific examples of preferred amorphous oxides and chalcogenides include Ga2O3, GeO, PbO, PbO2, Pb2O3, Pb2O4, Pb3O4, Sb2O3, Sb2O4, Sb2O8Bi2O3, Sb2O8Si2O3, Sb2O5, Bi2O3, Bi2O4, GeS, PbS, PbS2, Sb2S3, and Sb2S5.

[0071] The metal (composite) oxides and the chalcogenides preferably contain at least one of titanium and lithium as a constituent component from the viewpoint of high current density charge / discharge characteristics. Examples of lithium-containing metal composite oxides (lithium composite metal oxides) include composite oxides of lithium oxide and the metal (composite) oxides or the chalcogenides, more specifically Li2SnO2.

[0072] The negative electrode active material preferably contains titanium atoms. More specifically, TiNbO (niobium titanate oxide [NTO]), LiTiO 12 Lithium titanate (LTO) is preferred because it has small volume fluctuations when absorbing and releasing lithium ions, has excellent rapid charge and discharge characteristics, suppresses electrode deterioration, and can improve the life of lithium ion secondary batteries.

[0073] The lithium alloy as the negative electrode active material is not particularly limited as long as it is an alloy that is commonly used as a negative electrode active material for secondary batteries, and an example thereof is a lithium aluminum alloy.

[0074] The lithium-alloyable negative electrode active material is not particularly limited as long as it is commonly used as the negative electrode active material of a secondary battery. Examples of such active materials include negative electrode active materials having silicon atoms or tin atoms, and various metals such as Al and In. A negative electrode active material having silicon atoms (silicon atom-containing active material), which enables a higher battery capacity, is preferable, and a silicon atom-containing active material having a silicon atom content of 40 mol% or more of all constituent atoms is more preferable. Generally, negative electrodes containing these negative electrode active materials (for example, Si negative electrodes containing silicon atom-containing active materials, Sn negative electrodes containing active materials having tin atoms) can occlude more Li ions than carbon negative electrodes (such as graphite and acetylene black). That is, the amount of Li ions occluded per unit mass increases. Therefore, the battery capacity (energy density) can be increased. As a result, there is an advantage that the battery driving time can be lengthened. Examples of the silicon atom-containing active material include silicon materials such as Si and SiOx (0 < x ≤ 1), and further alloys containing titanium, vanadium, chromium, manganese, nickel, copper or lanthanum (for example, LaSi2, VSi2), or organized active materials (for example, LaSi2 / Si). In addition, active materials containing silicon atoms and tin atoms such as SnSiO3 and SnSiS3 are also included. Note that SiOx can be used as a negative electrode active material (semimetal oxide) itself, and can also be used as an active material (its precursor material) alloyable with lithium because Si is generated during the operation of the battery. Examples of the negative electrode active material having tin atoms include Sn, SnO, SnO2, SnS, SnS2, and further active materials containing the above silicon atoms and tin atoms. Also included are composite oxides with lithium oxide, for example, Li2SnO2.

[0075] In the present invention, the negative electrode active material is preferably a carbonaceous material, and more preferably artificial graphite.

[0076] The shape of the negative electrode active material is not particularly limited. The shape of the negative electrode active material is preferably particulate. The average particle diameter (average particle diameter in terms of spheres) of the negative electrode active material is preferably 0.1 to 60 μm, for example, preferably 0.5 to 50 μm, more preferably 1.0 to 40 μm, and even more preferably 5.0 to 30 μm. To obtain a predetermined particle size, a conventional grinder or classifier is used. For example, a mortar, ball mill, sand mill, vibration ball mill, satellite ball mill, planetary ball mill, swirling air jet mill, or sieve is preferably used. Wet grinding in the presence of water or an organic solvent such as methanol can also be performed during grinding. Classification is preferably performed to obtain a desired particle size. There are no particular limitations on the classification method, and a sieve, air classifier, or the like can be used as desired. Classification can be performed using either a dry method or a wet method.

[0077] The negative electrode active materials may be used singly or in combination of two or more. When forming a negative electrode active material layer, the unit area (cm 2 The mass (mg) (weight per unit area) of the negative electrode active material is not particularly limited and can be determined appropriately depending on the designed battery capacity.

[0078] The chemical formula of the compound obtained by the above calcination method can be measured by inductively coupled plasma (ICP) emission spectroscopy, or simply calculated from the difference in mass of the powder before and after calcination.

[0079] In the second embodiment of the electrode composition of the present invention, the content of the electrode active material in the composition is preferably 30 to 90 mass %, more preferably 50 to 85 mass %, and even more preferably 70 to 80 mass %. In the fourth embodiment of the electrode composition (electrode slurry) of the present invention, the content of the electrode active material is preferably as high as possible within a range that allows the desired low viscosity to be achieved. For example, the content of the electrode active material in the composition can be 49 to 90 mass%, more preferably 59 to 88 mass%, and even more preferably 65 to 83 mass%.

[0080] In the second embodiment of the electrode composition of the present invention, the content of the electrode active material in the total of the polymer X and the electrode active material is preferably 90.00 to 99.99 mass%, more preferably 95.00 to 99.95 mass%, and even more preferably 99.0 to 99.90 mass%. In the fourth embodiment of the electrode composition (electrode slurry) of the present invention, the content of the electrode active material in the total of the polymer X, the electrode active material, and the conductive assistant is preferably 30.0 to 99.8 mass%, more preferably 50.0 to 99.0 mass%, and even more preferably 70.0 to 97.0 mass%.

[0081] <Conductive additive> The electrode composition of the present invention may contain a conductive assistant. The conductive additive may be any of those known as general conductive additives. For example, the conductive additive may be an electron conductive material such as graphites (e.g., natural graphite, artificial graphite), carbon blacks (e.g., acetylene black, ketjen black, furnace black), amorphous carbon (e.g., needle coke), carbon fibers (e.g., vapor-grown carbon fiber, carbon nanotube), carbonaceous materials (e.g., graphene, fullerene), metal powders (e.g., copper, nickel), metal fibers, or conductive polymers (e.g., polyaniline, polypyrrole, polythiophene, polyacetylene, polyphenylene derivatives). In the present invention, the conductive additive is preferably a carbonaceous material, more preferably carbon black, and more preferably acetylene black. The electrode composition of the present invention has improved dispersibility of solid particles. From this viewpoint, carbon fibers such as carbon nanotubes, which usually have low dispersibility, can be preferably used. When an electrode active material and a conductive additive are used in combination, the conductive additive is one that does not insert or release Li when the battery is charged or discharged and does not function as an active material. Therefore, among the conductive additives, one that can function as an active material in the active material layer when the battery is charged or discharged is classified as an active material rather than a conductive additive. Whether or not a conductive additive functions as an active material when the battery is charged or discharged is not uniquely determined, but is determined by the combination with the active material.

[0082] The conductive additive may be used alone or in combination of two or more.

[0083] The shape of the conductive additive is not particularly limited, but is preferably in the form of particles. The median diameter (D50) of the conductive additive is not particularly limited and is, for example, preferably 0.01 to 50 μm, more preferably 0.1 to 10 μm, and even more preferably 0.2 to 2.0 μm.

[0084] In the third embodiment of the composition for an electrode of the present invention, the content of the conductive assistant in the composition is preferably 1 to 40 mass %, more preferably 3 to 30 mass %, and even more preferably 5 to 20 mass %. In the fourth embodiment of the electrode composition (electrode slurry) of the present invention, the content of the conductive aid in the composition is preferably 0.1 to 20 mass %, more preferably 0.5 to 10 mass %, and even more preferably 1 to 5 mass %.

[0085] In the third form of the electrode composition of the present invention (conductive assistant slurry), the content (mass %) of the conductive assistant in the total of the polymer X and the conductive assistant is preferably 10 to 99.9 mass %, more preferably 20 to 99 mass %, and even more preferably 30 to 95 mass %. In the fourth embodiment of the electrode composition (electrode slurry) of the present invention, the content (mass %) of the conductive auxiliary agent in the total of the polymer X, the electrode active material, and the conductive auxiliary agent is preferably 0.1 to 20 mass %, more preferably 0.5 to 15 mass %, even more preferably 1 to 10 mass %, and particularly preferably 2 to 5 mass %.

[0086] <Electrolytes> When the electrode composition of the present invention is an electrode slurry for a quasi-solid secondary battery, it contains an electrolyte. As the electrolyte, any electrolyte that can be used as an electrolytic solution for a quasi-solid secondary battery can be used appropriately. The electrolyte is preferably a metal salt, such as lithium salt, potassium salt, sodium salt, calcium salt, or magnesium salt. As the lithium salt, lithium salts that are commonly used in electrolytes for lithium ion secondary batteries are preferred, and examples thereof include the following lithium salts.

[0087] (L-1) Inorganic lithium salts: inorganic fluoride salts such as LiPF6, LiBF4, LiAsF6, and LiSbF6; perhalogenates such as LiClO4, LiBrO4, and LiIO4; inorganic chloride salts such as LiAlCl4;

[0088] (L-2) Fluorine-containing organic lithium salts: perfluoroalkanesulfonates such as LiCF3SO3, perfluoroalkanesulfonylimide salts such as LiN(CF3SO2)2, LiN(CF3CF2SO2)2, LiN(FSO2)2, LiN(CF3SO2)(C4F9SO2), perfluoroalkanesulfonylmethide salts such as LiC(CF3SO2)3, perfluoroalkyl fluorophosphates such as Li[PF5(CF2CF2CF3)], Li[PF4(CF2CF2CF3)2], Li[PF3(CF2CF2CF3)3], Li[PF5(CF2CF2CF2CF3)], Li[PF4(CF2CF2CF2CF3)2], Li[PF3(CF2CF2CF2CF3)3], etc.

[0089] (L-3) Oxalatoborate salts: lithium bis(oxalato)borate, lithium difluorooxalatoborate, etc.

[0090] Among these, LiPF6, LiBF4, LiAsF6, LiSbF6, LiClO4, Li(R f1 SO3), LiN(R f1 SO2)2, LiN(FSO2)2, or LiN(R f1 SO2)(R f2 SO2) are preferred, LiPF6, LiBF4, LiN(R f1 SO2)2, LiN(FSO2)2, or LiN(R f1 SO2)(R f2 SO2) is more preferred, and LiPF6 is particularly preferred. f1 and R f2 represents a perfluoroalkyl group, preferably having 1 to 6 carbon atoms.

[0091] The electrode composition may contain one electrolyte alone or two or more electrolytes in any combination.

[0092] When the electrode composition of the present invention is an electrode composition for a quasi-solid secondary battery, the electrolyte concentration of the electrode composition is not particularly limited as long as it functions as a non-aqueous electrolyte. For example, it can be 10.0 to 50.0 mass %, preferably 15.0 to 30.0 mass %. The molar concentration is preferably 0.5 to 1.5 M.

[0093] <Other ingredients> In addition to the above-mentioned components, the electrode composition of the present invention may optionally contain a binder, an ionic liquid, a thickener, an antifoaming agent, a leveling agent, a dehydrating agent, an antioxidant, etc. These may be those typically used in non-aqueous electrolyte secondary batteries. The binder is preferably polyvinylene difluoride (PVDF). The content of the binder in the electrode composition of the fourth embodiment of the electrode composition of the present invention (electrode slurry) is preferably 0.10 to 3.00 mass%, more preferably 0.20 to 2.00 mass%, even more preferably 0.20 to 1.00 mass%, and particularly preferably 0.25 to 0.40 mass%, of the solid content of the electrode composition. When a binder is added to the electrode compositions of the first to third embodiments of the present invention, it can be added so that the content is in the above range when the fourth electrode composition is prepared.

[0094] <Method for preparing electrode composition> The electrode composition of the present invention can be prepared as a mixture, preferably as a solution or slurry, by mixing the components constituting this composition in a mixer of various types.

[0095] <Electrode (electrode sheet) for non-aqueous electrolyte secondary batteries> The electrode (electrode sheet) for a non-aqueous electrolyte secondary battery of the present invention is an electrode formed using the electrode composition of the fourth embodiment. More specifically, it is an electrode including an electrode active material layer formed using the electrode composition of the fourth embodiment. The electrode of the present invention is an electrode suitable as an electrode for a non-aqueous electrolyte secondary battery. The electrode of the present invention is preferably a positive electrode. In the present invention, the simple term "electrode" encompasses both an embodiment in which the electrode is incorporated as a constituent member of a nonaqueous electrolyte secondary battery (a state in which the electrode is incorporated into a secondary battery) and an embodiment in which the electrode is an electrode material before being incorporated into a nonaqueous electrolyte secondary battery. In other words, the structure (area, thickness, etc.) of the electrode may be a structure that can be used as an electrode or a structure that can be processed into a structure that can be used as an electrode. The electrode of the present invention can have the same configuration as an electrode for a general non-aqueous electrolyte secondary battery, except that it has an electrode active material layer formed using the electrode composition of the fourth embodiment. The electrode of the present invention may have an electrode active material layer formed using the electrode composition of the fourth embodiment, and may be in a form in which the electrode active material layer and an electrode current collector are laminated. More specifically, the electrode active material layer may be laminated on both sides of the electrode current collector, or on one side of the electrode current collector. The electrode is usually a sheet configured by laminating an electrode active material layer on an electrode current collector.

[0096] The electrode of the present invention can be obtained by forming an electrode active material layer using the electrode composition of the fourth embodiment. For example, the electrode of the present invention can be produced by forming a film using the electrode composition of the present invention. More specifically, the electrode of the present invention can be prepared by forming the electrode active material layer on the electrode current collector or the like as a substrate. When the electrode composition of the present invention is an electrode composition for a general secondary battery, the electrode current collector is used as a substrate, and the electrode composition of the present invention is applied thereon (optionally via another layer) to form a coating film, which is then dried to obtain an electrode having an electrode active material layer (coated and dried layer) on the substrate. The coating film may be subjected to a press treatment as necessary. When the electrode composition of the present invention is an electrode composition for a quasi-solid secondary battery, the electrode active material layer can be formed by forming a coating film on the substrate. The method for applying the electrode composition of the present invention to a substrate is not particularly limited, and a conventional method can be used. The electrode active material layer obtained as described above may or may not contain a dispersion medium.

[0097] [Nonaqueous electrolyte secondary battery] The nonaqueous electrolyte secondary battery of the present invention (hereinafter also referred to as "secondary battery of the present invention") has the electrode of the present invention as an electrode. The secondary battery of the present invention can have the same configuration as a normal nonaqueous electrolyte secondary battery, except that it has the electrode of the present invention as an electrode. The secondary battery of the present invention preferably has the electrode of the present invention as a positive electrode. That is, the secondary battery of the present invention can be obtained by incorporating the electrode of the present invention as an electrode of a normal non-aqueous electrolyte secondary battery.

[0098] The structure of a typical non-aqueous electrolyte secondary battery will be described below. FIG. 1 is a cross-sectional view showing a schematic representation of the laminated structure of a typical nonaqueous electrolyte secondary battery 10, including the operating parts when the battery is in operation. The nonaqueous electrolyte secondary battery 10 has a laminated structure, viewed from the negative electrode side, having a negative electrode current collector 1, a negative electrode active material layer 2, a separator 3, a positive electrode active material layer 4, and a positive electrode current collector 5, in this order. The negative electrode active material layer 2, the positive electrode active material layer 4, and the space between them are filled with a nonaqueous electrolyte (not shown), and are separated by the separator 3. The separator 3 has pores, and during normal battery use, it functions as a separator between the positive and negative electrodes, allowing the electrolyte and ions to pass through these pores, insulating the positive and negative electrodes. With this structure, for example, in the case of a lithium-ion secondary battery, electrons (e - ) is supplied, and at the same time, lithium ions (Li + ) moves and accumulates in the negative electrode. On the other hand, during discharge, the lithium ions (Li + ) is returned to the positive electrode side through the electrolyte, and electrons are supplied to the operating part 6. In the example shown, a light bulb is used as the operating part 6, and it is lit by the discharge. The secondary battery of the present invention has a positive electrode of the present invention instead of the positive electrode active material layer 4 and the positive electrode current collector 5 of the above-mentioned general nonaqueous electrolyte secondary battery, and / or has a negative electrode of the present invention instead of the negative electrode current collector 1 and the negative electrode active material layer 2.

[0099] Next, the basic structure characteristic of quasi-solid secondary batteries will be described. In quasi-solid secondary batteries, the electrode active material layer is an electrode slurry layer formed by dispersing an electrode active material in a non-aqueous electrolyte. Therefore, the structure of a quasi-solid secondary battery differs from that of a general non-aqueous electrolyte secondary battery in that the electrode active material layer is a slurry (suspension, dispersion) formed by dispersing an electrode active material in a non-aqueous electrolyte. That is, in a typical nonaqueous electrolyte secondary battery, a coating solution is prepared by dispersing an electrode active material in a medium that does not contain an electrolyte, and the coating solution is applied to a current collector to form a coating film, which is then dried to form a thin-film electrode active material layer. A binder is usually blended into the coating solution, forming a hard electrode active material layer in which the electrode active material particles are firmly bound together. Since the nonaqueous electrolyte is present on the electrode active material layer thus formed (between the negative electrode active material layer and the positive electrode active material layer), the electrode active material layer is in the form of a hard solid particle layer overall, not a slurry layer, even if there are portions in the electrode active material layer through which the nonaqueous electrolyte can penetrate. In contrast, in a quasi-solid secondary battery, the electrode active material layer is an electrode slurry layer formed by dispersing solid particles containing an electrode active material and a conductive additive in a non-aqueous electrolyte solution obtained by dissolving a lithium salt (electrolyte) in a non-aqueous solvent. For this electrode slurry layer to function as an electrode active material layer, strong binding between the electrode active material particles is not required, and therefore the electrode slurry layer usually does not contain a binder. Except for the fact that the electrode active material layer is an electrode slurry layer and that the electrode slurry layer is in contact with a separator, the basic layer configuration of a quasi-solid secondary battery is the same as the layer configuration shown in FIG. 1.

[0100] When the secondary battery of the present invention is a general non-aqueous electrolyte secondary battery, the electrode active material layer is a layer obtained by applying the electrode composition of the second or fourth aspect of the present invention and drying it as necessary. When the secondary battery of the present invention is a quasi-solid secondary battery, the electrode active material layer is a layer formed from the electrode composition for a quasi-solid secondary battery of the present invention.

[0101] The secondary battery of the present invention is provided with the electrode of the present invention as an electrode of the secondary battery, and other components such as a positive electrode active material, a positive electrode current collector, a negative electrode active material layer, a negative electrode current collector, an electrolyte such as an electrolyte (aqueous electrolyte, non-aqueous electrolyte), a separator, etc. are not particularly limited. These materials and components can be appropriately applied to those used in ordinary secondary batteries. In addition, for the method of manufacturing the secondary battery of the present invention, ordinary methods can be appropriately adopted except that the electrode of the present invention is used as an electrode. For components and manufacturing methods commonly used in these secondary batteries, for example, JP 2016-201308 A, JP 2005-108835 A, JP 2012-185938 A, and WO 2020 / 067106 A can be appropriately referenced.

[0102] The secondary battery of the present invention can be installed in electronic devices such as notebook computers, pen-input PCs, mobile PCs, electronic book players, mobile phones, cordless phone handsets, pagers, handheld terminals, portable fax machines, portable copiers, portable printers, headphone stereos, video camcorders, LCD televisions, handheld vacuum cleaners, portable CD players, mini-discs, electric shavers, transceivers, electronic organizers, calculators, memory cards, portable tape recorders, radios, backup power supplies, and memory cards. It can also be installed in consumer devices such as automobiles, electric vehicles, motors, lighting fixtures, toys, game devices, road conditioners, clocks, flash devices, cameras, and medical devices (pacemakers, hearing aids, shoulder massagers, etc.). It can also be used for various military and space applications. It can also be combined with solar cells.

[0103] The present invention will be described in more detail below with reference to examples, but the present invention should not be construed as being limited thereto. [Example]

[0104] [Method for synthesizing polymer X and method for preparing polymer X solution (first embodiment of the electrode composition of the present invention)] (Polymer used in Example 1) To a 100 mL measuring cylinder, 15 g of N-cyclohexylmaleimide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a monomer from which component (a) is derived, 15 g of ethyl acrylate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a monomer from which component (b) is derived, 35 g of N-methylpyrrolidone (NMP) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a dispersion medium, and 0.1 g of polymerization initiator V-601 (trade name, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to prepare monomer solution a. The SP value of NMP was 22 MPa. 1 / 2 It was. 35 g of N-methylpyrrolidone was added to a 300 mL three-neck flask and stirred at 80°C under a nitrogen atmosphere, to which the above-mentioned monomer solution a was added dropwise over 2 hours. After the dropwise addition was completed, the temperature was raised to 90°C and stirring was continued for 2 hours to obtain polymer solution S1 containing a polymer having a structure derived from N-cyclohexylmaleimide as component (a) and a structure derived from ethyl acrylate as component (b), and NMP as a dispersion medium. The weight-average molecular weight (Mw) of the obtained polymer was 5800. The solids concentration of polymer solution S1 was 30% by mass.

[0105] (Polymer used in Example 2) The polymer used in Example 2 and its polymer solution S2 were obtained in the same manner as in the synthesis of the polymer used in Example 1, except that the type of monomer from which component (a) was derived was γ-butyrolactone acrylamide.

[0106] (Polymer used in Example 3) The polymer used in Example 3 and its polymer solution S3 were obtained in the same manner as in the synthesis of the polymer used in Example 1, except that in the synthesis method of the polymer used in Example 1, the type of monomer from which component (a) was derived was mevalonolactone methacrylate.

[0107] (Polymer used in Example 4) The polymer used in Example 4 and its polymer solution S4 were obtained in the same manner as in the synthesis of the polymer used in Example 1, except that the type of monomer from which component (a) was derived was N-cyclohexyl acrylamide.

[0108] (Polymer used in Example 5) The polymer used in Example 5 and its polymer solution S5 were obtained in the same manner as in the synthesis of the polymer used in Example 1, except that the type of monomer from which component (a) was derived was 1-adamantylacrylamide.

[0109] (Polymer used in Example 6) In the synthesis method of the polymer used in Example 1, the monomer from which component (a) is derived is 2-oxo-2-[(5-oxo-4-oxatricyclo[4.2.1.0 3,7 A polymer to be used in Example 6 and its polymer solution S6 were obtained in the same manner as in Example 1, except that the hydroxyl group was 2-(2-hydroxypropyl)-2-nonan-2-yl)oxyethyl.

[0110] (Polymer used in Example 7) The polymer used in Example 6 and its polymer solution S7 were obtained in the same manner as in the synthesis of the polymer used in Example 1, except that the monomer from which component (a) was derived was 2-oxohexahydro-2H-3,5-methanocyclopenta[b]furan-6-yl methacrylate.

[0111] (Polymer used in Example 8) The polymer used in Example 8 and its polymer solution S8 were obtained in the same manner as in the synthesis of the polymer used in Example 1, except that the type of monomer from which component (a) was derived was N-cyclopentylacrylamide.

[0112] (Polymer used in Example 9) The polymer used in Example 9 and its polymer solution S9 were obtained in the same manner as in the synthesis of the polymer used in Example 1, except that the type of monomer from which component (a) was derived was γ-butyrolactone acrylate.

[0113] (Polymer used in Example 10) The polymer used in Example 10 and its polymer solution S10 were obtained in the same manner as in the synthesis of the polymer used in Example 8, except that in the synthesis method of the polymer used in Example 8, the monomer from which component (b) was derived was benzyl acrylate.

[0114] (Polymer used in Example 11) The polymer used in Example 11 and its polymer solution S11 were obtained in the same manner as in the synthesis of the polymer used in Example 8, except that in the synthesis method of the polymer used in Example 8, the monomer from which component (b) was derived was stearyl acrylate.

[0115] (Polymer used in Example 12) The polymer used in Example 12 and its polymer solution S12 were obtained in the same manner as in the synthesis of the polymer used in Example 11, except that in the synthesis method for the polymer used in Example 11, the amount of the monomer leading to component (a) was 7.5 g and the amount of the monomer leading to component (b) was 22.5 g.

[0116] (Polymer used in Example 13) The polymer used in Example 13 and its polymer solution S13 were obtained in the same manner as in the synthesis of the polymer used in Example 11, except that in the synthesis method of the polymer used in Example 11, the amount of the monomer leading to component (a) was 22.5 g and the amount of the monomer leading to component (b) was 7.5 g.

[0117] (Polymer used in Example 14) The polymer used in Example 14 and its polymer solution S14 were obtained in the same manner as in the synthesis of the polymer used in Example 11, except that in the synthesis method of the polymer used in Example 11, the amount of monomer leading to component (a) was 30 g and no monomer leading to component (b) was used.

[0118] (Polymer used in Example 15) The polymer used in Example 15 and its polymer solution S15 were obtained in the same manner as in the synthesis of the polymer used in Example 11, except that the Mw was adjusted to 30,000.

[0119] (Polymer used in Example 16) The polymer used in Example 16 and its polymer solution S16 were obtained in the same manner as in the synthesis of the polymer used in Example 11, except that the Mw was set to 80,000.

[0120] (Polymer used in Comparative Example 1) The polymer used in Comparative Example 1 and its polymer solution cS1 were obtained in the same manner as in Example 1, except that the monomer from which component (a) was derived was methoxyethyl acrylate. Although methoxyethyl acrylate is not a monomer from which component (a) is derived due to its structure, for the sake of convenience, it is listed as a monomer from which component (a) is derived in the explanations and tables. The same applies to the compounds used in Comparative Examples 2 to 4.

[0121] (Polymer used in Comparative Example 2) The polymer used in Comparative Example 2 and its polymer solution cS2 were obtained in the same manner as in Example 1, except that in the synthesis method for the polymer used in Example 1, the type of monomer from which component (a) was derived was vinylpyrrolidone.

[0122] (Polymer used in Comparative Example 3) The polymer used in Comparative Example 3 and its polymer solution cS3 were obtained in the same manner as in Example 1, except that in the synthesis method for the polymer used in Example 1, the type of monomer from which component (a) was derived was 1-ethylcyclohexyl methacrylate.

[0123] (Polymer used in Comparative Example 4) The polymer used in Comparative Example 4 and its polymer solution cS4 were obtained in the same manner as in Example 1, except that in the synthesis method for the polymer used in Example 1, the type of monomer from which component (a) was derived was 2-methyladamantyl methacrylate.

[0124] [Preparation of Conductive Aid Slurry (Third Form of Electrode Composition of the Present Invention)] (Conductive assistant slurry CAS1 of Example 1) Conductive additive slurry CAS1 was prepared using acetylene black (AB) (Denka Black Powder, manufactured by Denka Co., Ltd.) as the conductive additive, a polyvinylidene fluoride NMP solution (12 mass% NMP solution of #1100, manufactured by Kureha Corporation) as the binder, and NMP as the dispersion medium. Furthermore, polymer solution S1 was used. The mass ratio of conductive additive, binder, and polymer X in conductive additive slurry CAS1 was 50:50:2.5 (solid content equivalent). The amount of NMP was adjusted to a solid content of 14 mass%. The conductive additive slurry CAS1 was degassed and stirred using a planetary mixer (Awatori Rentaro) (stirring: 2000 rpm × 4 min, degassing: 2200 rpm × 1 min). In this way, conductive additive slurry CAS1 was obtained, containing NMP and a polymer composed of N-cyclohexylmaleimide-derived and ethyl acrylate-derived structures.

[0125] (Conductive assistant slurries CAS2 to CAS16 of Examples 2 to 16) Conductive assistant slurries CAS2 to CAS16 of Examples 2 to 17 were obtained in the same manner as in the preparation of the conductive assistant slurry CAS1 of Example 1, except that the polymer solutions shown in Table 1 were used instead of the conductive assistant slurry CAS1 of Example 1.

[0126] (Conductive assistant slurries cCAS1 to cCAS4 of Comparative Examples 1 to 4) Conductive assistant slurries cCAS1 to cCAS4 of Comparative Examples 1 to 4 were obtained in the same manner as in the preparation of the conductive assistant slurry CAS1 of Example 1, except that the polymer solutions shown in Table 1 were used instead of the conductive assistant slurry CAS1 of Example 1.

[0127] [Dispersion viscosity] The dispersibility of solid particles in the electrode composition was confirmed using dispersion viscosity as an index. Of the solid particles that can be contained in the electrode composition, the conductive additive is usually the least dispersible. For this reason, in this test, only the conductive additive was used as the dispersoid. The dispersion viscosity of each of the conductive additive slurries obtained above was measured. An E-type viscometer was used to measure the viscosity, and the dispersion viscosity was read at a shear rate of 10 / s. The obtained dispersion viscosity was evaluated according to the following evaluation criteria. - Evaluation Criteria - A: Less than 8000cP B: 8000cP or more, less than 10000cP C: 10,000 cP or more, less than 15,000 cP D: 15,000 cP or more, less than 20,000 cP E: 20,000 cP or more, less than 30,000 cP F:30000cP or more

[0128] [Oxidation resistance evaluation] The oxidation resistance of polymer X was confirmed using the oxidation voltage as an index. Each of the above conductive additive slurries was applied to one side of an aluminum foil having a thickness of 20 μm and then thoroughly dried to prepare an aluminum foil having a conductive additive layer (aluminum foil with a conductive additive layer). The coating mass of each conductive additive slurry was 10 mg / cm. 2 It was. Three-electrode cells were assembled using each of the aluminum foils with conductive additive layers as the working electrode and lithium foils as the counter and reference electrodes. Cyclic voltammetry measurements were performed using the resulting three-electrode cells at a sweep voltage of 3 to 5 V and a sweep rate of 1 mV / sec. The electrolyte used was a 1 M solution of LiPF6 in a mixed solvent of EC and DEC in a volume ratio of 3:7. The voltage at which current began to flow (oxidation voltage) was measured. The resulting voltages were evaluated according to the following criteria: the higher the voltage, the better the oxidation resistance. - Evaluation Criteria - A:4.4V or more B: 4.2V or more, less than 4.4V C: 4.0V or more, less than 4.2V D: 3.8V or more, less than 4.0V E: 3.6V or more, less than 3.8V F: Less than 3.6V

[0129] [Preparation of Positive Electrode Slurry (Fourth Form of Electrode Composition of the Present Invention)] (Positive electrode slurry of Example 1) The conductive additive slurry CAS1, NMP, and polyvinylidene fluoride NMP solution (12 mass% NMP solution of #1100 manufactured by Kureha Corporation) were weighed into a 50 ml sample bottle, and LiCoO2 (Cellseed (product name) manufactured by Nippon Chemical Industry Co., Ltd.) was added as a positive electrode active material. The mixture was further stirred for 5 minutes using a planetary centrifugal mixer (Thinky Corporation, Awatori Rentaro (product name)) to obtain the positive electrode slurry of Example 1. The mass ratio of the positive electrode active material, binder (PVDF), conductive additive, and polymer X was 100:3:3:0.15 (solid content equivalent), and the solid content (mass %) of the positive electrode slurry was 73.8 mass %. The total solid content of the positive electrode slurry is the total mass of the positive electrode active material, binder, conductive additive, and polymer contained in the positive electrode slurry.

[0130] (Positive electrode slurries of Examples 2 to 16) Positive electrode slurries of Examples 2 to 16 were obtained in the same manner as in the preparation of the positive electrode slurry of Example 1, except that the conductive additive slurries were changed to conductive additive slurries CAS2 to CAS16.

[0131] (Positive electrode slurries of Comparative Examples 1 to 4) Positive electrode slurries of Comparative Examples 1 to 4 were obtained in the same manner as in the preparation of the positive electrode slurry of Example 1, except that the conductive assistant slurries were changed to conductive assistant slurries cCAS1 to cCAS4.

[0132] [Preparation of positive electrode] Each of the positive electrode slurries obtained above was applied to one side of a 20 μm thick aluminum foil (current collector) as a substrate and thoroughly dried to prepare a positive electrode having a positive electrode active material layer on the aluminum foil. The mass of the positive electrode active material layer after drying was 17 mg / cm. 2 It was.

[0133] [Preparation of negative electrode] 94.8 parts by weight of commercially available graphite for negative electrode active materials, 1.7 parts by weight of acetylene black, 2 parts by weight of SBR (styrene-butadiene rubber), and 1.5 parts by weight of CMC (carboxymethyl cellulose) were mixed. Subsequently, distilled water, a solvent, was added to the mixture to prepare a slurry. The slurry was applied to a surface of electrolytic copper foil to a thickness of approximately 100 μm, dried at 120°C, and then roll-pressed to prepare a negative electrode.

[0134] [Evaluation method: Battery evaluation] <Discharge capacity maintenance rate> A 1M solution of LiPF6 as a solute in a non-aqueous organic solvent prepared by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) in a 1:1 mass ratio was prepared as electrolyte I. A coin battery was manufactured using the negative electrode, positive electrode, and electrolyte I prepared above, and the battery characteristics were measured as follows. The coin battery was charged at a C rate of 0.2C under the following conditions in an environment of 25°C until the battery voltage reached 4.2V, and then discharged at a C rate of 0.2C until the battery voltage reached 3V, and the discharge capacity (Ah) at 0.2C was determined. (Charging conditions) 0.2C CC (constant current)-CV (constant voltage) charging: Upper limit voltage 4.2V, end current 0.02C (discharge conditions) 0.2C CC (constant current) discharge: End voltage 3V Next, the discharge capacity at 5C was determined in the same manner as in the measurement of the discharge capacity at 0.2C, except that the C rates during charging and discharging were changed to 5C. The discharge capacity retention rate at 5 C was calculated using the discharge capacity at 0.2 C as the reference discharge capacity according to the following formula: The obtained discharge capacity retention rate was applied to the following evaluation criteria to evaluate the battery performance. Discharge capacity retention rate at 5 C (%) = (discharge capacity at 5 C / discharge capacity at 0.2 C) × 100 - Evaluation Criteria - A: 75% or more B: 70% or more, less than 75% C: 65% or more, less than 70% D: 60% or more, less than 65% E: 55% or more, less than 60% F: Less than 55%

[0135] The results obtained are shown in Table 1.

[0136] [Table 1]

[0137] (Note to Table 1) The "structure" of component (a) and component (b) describes the monomers that lead to each component. The "composition ratio" indicates the content (% by mass) of the constituent component (a) or (b) in the polymer X.

[0138] In Comparative Examples 1 to 4, where the polymer X does not contain the component (a), the dispersion viscosity of the conductive additive slurry was as high as 30,000 cP or more, resulting in poor dispersibility, or the oxidation voltage of the positive electrode was less than 3.6 V, resulting in poor oxidation resistance. Comparative Example 2, which was poor in oxidation resistance, also had a discharge capacity retention rate of 55% or less, resulting in poor results. From Comparative Examples 3 and 4, it can be seen that in the structure (i), R 12 It is clear that when is a substituent containing an aliphatic hydrocarbon ring structure, the effects of the present invention cannot be obtained. In contrast, in Examples 1 to 16 in which the polymer X contained the constituent component (a), the dispersion viscosity of the conductive additive slurry was less than 15,000 cP, the oxidation voltage of the positive electrode was 4.0 V or more, and the discharge capacity retention rate was 65% or more. It can be seen that by using the electrode composition of the present invention, solid particles can be dispersed efficiently, and when formed into an electrode, oxidation resistance can be improved. [Explanation of symbols]

[0139] 10 Nonaqueous electrolyte secondary battery 1 Negative electrode current collector 2 Negative electrode active material layer 3 Separator 4 Cathode active material layer 5 Positive electrode current collector 6. Working part (bulb)

Claims

1. A composition for an electrode containing a polymer X and a dispersion medium, The composition for an electrode of a non-aqueous electrolyte secondary battery, wherein the polymer X contains at least a component (a) represented by any one of the following (i) to (iii): 【Chemistry 1】 In the above formula, R １１ and R ２１ represents a hydrogen atom or an alkyl group. R １２ represents a substituent containing a lactone ring structure. R ２２ and R ３ represents a substituent containing a lactone ring structure or an aliphatic hydrocarbon ring structure. * indicates a binding site for incorporation into the polymer.

2. 2. The electrode composition according to claim 1, wherein the content of the constituent component (a) in the polymer X is 20% by mass or more.

3. 3. The electrode composition according to claim 2, wherein the polymer X comprises a component (b) different from the component (a), and the component (b) has at least one of an aromatic hydrocarbon group and an acyclic aliphatic hydrocarbon group having 2 to 50 carbon atoms.

4. 4. The electrode composition according to claim 3, wherein the polymer X has a weight average molecular weight of 1,000 to 30,000.

5. The electrode composition according to claim 4 , wherein the dispersion medium is an organic solvent.

6. The electrode composition according to claim 5 , further comprising a conductive additive.

7. The electrode composition according to claim 6 , comprising an electrode active material.

8. The electrode composition according to claim 7 , wherein the electrode active material is a positive electrode active material.

9. An electrode for a non-aqueous electrolyte secondary battery, formed using the electrode composition according to claim 7.

10. A non-aqueous electrolyte secondary battery having the electrode for a non-aqueous electrolyte secondary battery according to claim 9 as an electrode.

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