Binder for electrode, electrode, and power storage device

Abstract

The present invention provides a binder for an electrode excellent in binding property without impairing battery performance when used for a power storage device.　The problem is solved by using an electrode binder having a polymer containing, as polymerization components, a constituent unit derived from triazine thiol having an unsaturated group and / or a constituent unit derived from a phosphoric acid ester having an unsaturated group, thereby completing the present invention.

Description

Electrode binder, electrode, and electricity storage device

[0001] The present invention relates to an electrode binder used in electricity storage devices such as secondary batteries, such as lithium ion secondary batteries and nickel-metal hydride secondary batteries, and electrochemical capacitors, particularly non-aqueous electrolyte electricity storage devices that use a non-aqueous electrolyte, such as an organic solvent, as the electrolyte; an electrode containing the electrode binder; and an electricity storage device equipped with the electrode.

[0002] Energy storage devices such as lithium-ion secondary batteries and electrochemical capacitors are used in electronic devices such as mobile phones and laptops. Recently, due to growing awareness of environmental protection and the development of related laws, their application as storage batteries for in-vehicle use in electric vehicles and hybrid electric vehicles, as well as for home energy storage, has been expanding.

[0003] Furthermore, as these applications advance, higher performance is required for electricity storage devices, and improvements are being made to components such as electrodes. Electrodes used in such electricity storage devices are usually obtained by applying an electrode material consisting of an active material, a conductive additive, a binder, and a solvent onto a current collector and drying the applied material.

[0004] Therefore, in recent years, attempts have been made to improve the binders used in electrodes, and it has been proposed that improving the binders will improve the binding strength between active materials, between the active material and the conductive additive, and between the active material and the current collector, thereby improving electrical properties (e.g., cycle characteristics, output characteristics at low temperatures, and lower resistance).

[0005] Binders are required to have excellent binding properties when used in electrodes and to be able to impart excellent electrical properties to electricity storage devices, and new binders have been proposed. However, in recent years, binders with particularly excellent binding properties have been required, and further investigation is required.

[0006] Therefore, the present applicant has developed a binder having a reactive group as disclosed in Patent Document 1 in order to develop a binder that has better binding properties and exhibits favorable characteristics when used in an electricity storage device, but further investigation is required.

[0007] International Publication No. 2023 / 053863

[0008] An object of the present invention is to provide an electrode binder that does not impair battery performance when used in an electricity storage device and has excellent binding properties.

[0009] As a result of extensive investigations into achieving the above-mentioned object, the present inventors have found that the above-mentioned object can be achieved by using an electrode binder having a polymer containing, as a polymerization component, a structural unit derived from a triazine thiol having an unsaturated group and / or a structural unit contained in a phosphate ester having an unsaturated group, and have thereby completed the present invention.

[0010] That is, the present invention relates to the following: Item 1. An electrode binder comprising a polymer, wherein the polymer comprises a structural unit (A), and the structural unit (A) is a structural unit derived from a triazine thiol having an unsaturated group and / or a structural unit derived from a phosphate ester having an unsaturated group. Item 2. The electrode binder according to Item 1, wherein the polymer comprises a structural unit derived from a (meth)acrylic acid ester. Item 3. The electrode binder according to Item 2, wherein the polymer comprises 40 mass% or more of the structural unit derived from the (meth)acrylic acid ester. Item 4. The electrode binder according to Item 2 or 3, wherein the structural unit derived from the (meth)acrylic acid ester comprises at least one structural unit selected from the group consisting of a structural unit (B) derived from a (meth)acrylic acid alkyl ester monomer and a structural unit (C) derived from an acrylic acid ester monomer having an aromatic group. Item 5. Item 5. The electrode binder according to any one of items 1 to 4, wherein in the structural unit (A), the structural unit derived from a phosphate ester having an unsaturated group has a chemical structure represented by the following general formula (A): [In general formula (A), AO is an alkylene oxide group, and n is an integer of 1 to 6.] Item 6. An electrode comprising the electrode binder according to any one of Items 1 to 5. Item 7. The electrode according to Item 6, wherein the active material (100 mass%) in the electrode contains 20 mass% or more of a silicon-based compound. Item 8. An electricity storage device comprising the electrode according to Item 6 or 7.

[0011] The binder of the present invention contains, as a polymerization component of the polymer, a structural unit derived from a triazine thiol having an unsaturated group and / or a structural unit of a phosphate ester having an unsaturated group, thereby achieving strong bonding with the active material and the current collector, thereby preventing electrode peeling and improving the work process.When used in an electricity storage device, the binder does not impair battery performance, and is therefore useful in automobile applications such as electric vehicles and hybrid electric vehicles, as well as in electricity storage devices such as storage batteries for home power storage.

[0012] In this specification, the term "electricity storage device" includes secondary batteries (lithium ion secondary batteries, nickel-metal hydride secondary batteries, etc.) and electrochemical capacitors. Furthermore, in this specification, "(meth)acrylate" means "acrylate or methacrylate," and the same applies to similar expressions.

[0013] In this specification, a numerical value connected with "~" means a numerical range that includes the numerical values ​​before and after "~" as the lower limit and upper limit. When multiple lower limit values ​​and multiple upper limit values ​​are listed separately, any lower limit value and upper limit value can be selected and connected with "~".

[0014] 1. Electrode Binder The electrode binder of the present invention is an electrode binder containing a polymer having structural units derived from a triazine thiol having an unsaturated group and / or structural units derived from a phosphate ester having an unsaturated group. The polymer contained in the electrode binder of the present invention is preferably a (meth)acrylic polymer, and preferably contains 40 mass % or more, more preferably 60 mass % or more, and particularly preferably 80 mass % or more of structural units derived from a (meth)acrylic acid ester monomer.

[0015] The structural unit derived from a triazine thiol having an unsaturated group is preferably a structural unit derived from a triazine dithiol having an unsaturated group, and examples thereof include structural units derived from 6-diallylamino-1,3,5-triazine-2,4-dithiol, 6-(allylamino)-1,3,5-triazine-2,4-dithiol, 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithiol, etc. In forming the structural unit derived from a triazine thiol having an unsaturated group, these monomers may be used alone or in combination of two or more appropriately selected types. The molecular weight of the triazine thiol having an unsaturated group described as a structural unit (i.e., triazine thiol having an unsaturated group as a monomer) is preferably 50 to 1,000, and more preferably 100 to 500.

[0016] The structural unit derived from a phosphate ester having an unsaturated group is preferably a structural unit derived from a (meth)acrylate phosphate. Specific examples of the (meth)acrylate phosphate include (meth)acrylic acid ester derivatives, phosphates of hydroxyalkyl (meth)acrylates, phosphate monoesters of 2-hydroxyethyl (meth)acrylate, phosphate monoesters of 2-hydroxypropyl (meth)acrylate, phosphate monoesters of 3-hydroxypropyl (meth)acrylate, phosphate diesters of 2-hydroxyethyl (meth)acrylate, phosphate diesters of 2-hydroxypropyl (meth)acrylate, phosphate diesters of 3-hydroxypropyl (meth)acrylate, (meth)acryloyloxyalkyl monophosphates such as (meth)acryloyloxyethyl phosphate, methacryloxypolyethylene glycol phosphate, methacryloxypolypropylene glycol phosphate, aromatic-containing phosphate esters such as phenyl 2-(methacryloyloxy)ethyl hydrogen phosphate, and phosphate monoester group-containing vinyl monomers and phosphate diester group-containing vinyl monomers such as hydrogen phosphate=bis[2-(methacryloyloxy)ethyl]. In forming the structural unit derived from the phosphate ester having an unsaturated group, these monomers may be used alone or in combination of two or more appropriately selected types. The molecular weight of the phosphate ester having an unsaturated group described as a structural unit (i.e., the phosphate ester having an unsaturated group as a monomer) is preferably 50 to 1,000, and more preferably 100 to 500.

[0017] From the viewpoint of more suitably exerting the effects of the present invention, the constituent unit derived from a phosphate ester having an unsaturated group is preferably derived from a phosphate ester (monomer) having an unsaturated group, which has a chemical structure represented by the following general formula (A):

[0018]

[0019] In general formula (A), AO is an alkylene oxide group, and n is an integer of 1 to 6. AO is preferably an alkylene oxide having 2 to 4 carbon atoms, such as ethylene oxide, propylene oxide, or butylene oxide, and more preferably ethylene oxide or propylene oxide. In general formula (A), the alkylene oxide constituting AO may be of only one type, or may be of two or more types.

[0020] The lower limit of the proportion of the structural unit (A) in the polymer (i.e., the proportion of the structural unit (A) in 100% by mass of all structural units constituting the polymer) is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, and the upper limit is preferably 3% by mass or less, more preferably 2% by mass or less, and particularly preferably 1% by mass or less.

[0021] In the electrode binder of the present invention, the polymer preferably further contains, as a constituent unit derived from a (meth)acrylic acid ester, a constituent unit (B) derived from a (meth)acrylic acid alkyl ester monomer.

[0022] The structural unit (B) is preferably a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group containing 1 to 22 carbon atoms, more preferably a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group containing 2 to 18 carbon atoms, and particularly preferably a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group containing 4 to 18 carbon atoms.

[0023] Specific examples of preferred structural units (B) include structural units derived from alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, and stearyl (meth)acrylate. The structural unit (A) may be of one type, or two or more types.

[0024] When the polymer contains the structural unit (B), the lower limit of the proportion of the structural unit (B) in the polymer (i.e., the proportion of the structural unit (B) in 100% by mass of all structural units constituting the polymer) is preferably 30% by mass or more, and more preferably 40% by mass or more, and the upper limit is preferably 65% ​​by mass or less, more preferably 60% by mass or less, and particularly preferably 55% by mass or less.

[0025] In the electrode binder of the present invention, the polymer preferably further contains, as a constituent unit derived from a (meth)acrylic acid ester, a constituent unit (C) derived from an acrylic acid ester monomer having an aromatic group.

[0026] The structural unit (C) is preferably a structural unit derived from a monomer (compound) represented by the following general formula (1). (In general formula (1), R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R 2 represents an aromatic group which may have a substituent.

[0027] In the monomer represented by general formula (1), R 1is hydrogen or an alkyl group having 1 to 4 carbon atoms, preferably hydrogen or an alkyl group having 1 to 2 carbon atoms, and particularly preferably hydrogen or a methyl group. 2 is an aromatic group which may have a substituent, and examples of the substituent include alkyl groups such as methyl, ethyl, and isopropyl groups, unsaturated hydrocarbon groups such as vinyl groups, halogeno groups such as fluoro, chloro, bromo, and iodo groups, amino groups, nitro groups, and carboxyl groups. 2 may have two or more aromatic rings.

[0028] More specifically, the constituent unit derived from the monomer (compound) represented by general formula (1) is preferably a constituent unit derived from the monomer (compound) represented by the following general formula (2). (In general formula (2), R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, and R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12 is any one of hydrogen, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, and an aromatic group which may have a substituent, and R 13 represents an alkylene group having 1 to 3 carbon atoms or a carbonyl group, R 14 is an aromatic group which may have a substituent, q and r are numbers from 0 to 3, and s is a number from 0 to 1.

[0029] In the monomer represented by general formula (2), R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, preferably hydrogen or an alkyl group having 1 to 2 carbon atoms, and particularly preferably hydrogen or a methyl group. 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , R 10 , R 11 , R 12is any one of hydrogen, a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, and an aromatic group which may have a substituent, and is preferably any one of hydrogen, a hydroxyl group, an alkyl group having 1 to 2 carbon atoms, and an aromatic group which may have a substituent. 13 is an alkylene group having 1 to 3 carbon atoms or a carbonyl group, and is preferably an alkylene group having 1 to 2 carbon atoms or a carbonyl group. 14 is an aromatic group which may have a substituent, and the aromatic group is preferably an aryl group, a benzyl group, or a phenoxy group. Examples of the substituent include alkyl groups such as methyl, ethyl, or isopropyl; unsaturated hydrocarbon groups such as vinyl; halogeno groups such as fluoro, chloro, bromo, or iodo; amino, nitro, or carboxyl. The aromatic ring may have two or more rings. q and r are numbers from 0 to 3, preferably from 0 to 2, and may satisfy the relationship q+r≧1, and s is a number from 0 to 1.

[0030] Specific examples of the monomer represented by general formula (1) include benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, neopentyl glycol-(meth)acrylic acid-benzoic acid ester, 2-(meth)acryloyloxyethyl-phthalic acid, etc. The monomer represented by general formula (1) that forms the structural unit (C) may be of one type, or may be of two or more types.

[0031] When the polymer contains the structural unit (C), the lower limit of the proportion of the structural unit (C) in the polymer (i.e., the proportion of the structural unit (C) in 100% by mass of all structural units constituting the polymer) is preferably 20% by mass or more, more preferably 25% by mass or more, and particularly preferably 30% by mass or more. The upper limit of the proportion of the structural unit (C) in the polymer is preferably 60% by mass or less, more preferably 50% by mass or less, and particularly preferably 45% by mass or less. Setting the proportion in this range is preferable in that the affinity between the current collector foil and the active material is improved when used in an electrode.

[0032] In the polymer, the total proportion of the structural unit (B) and the structural unit (C) (i.e., the total proportion of the structural unit (B) and the structural unit (C) in 100% by mass of all structural units constituting the polymer) is preferably 70% by mass or more, more preferably 75% by mass or more, and particularly preferably 80% by mass or more.

[0033] It is preferable that the polymer further contains, as a structural unit derived from a (meth)acrylic acid ester, a structural unit (D) derived from a monomer represented by the following general formula (3), in terms of improving ionic conductivity when used in an electrode. (In general formula (3), R 15 is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, x is an integer of 2 to 8, n is an integer of 2 to 30, and R 15a is an alkyl group having 1 to 6 carbon atoms, an aromatic group, or a hydrogen atom.

[0034] In general formula (3), R 15 As the structural unit (D), preferably, a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, etc. are mentioned. A hydrogen atom or a methyl group is preferable. That is, in the structural unit (D), the monomer having a hydroxyl group is (R 15 is a hydrogen atom or a methyl group).

[0035] In the general formula (3), (C x H 2xO) is a linear or branched alkyl ether group, and x is an integer of 2 to 8, preferably an integer of 2 to 7, and more preferably an integer of 2 to 6.

[0036] In the general formula (3), n is an integer of 2 to 30, preferably an integer of 2 to 25, and more preferably an integer of 2 to 20.

[0037] In general formula (3), R 15a is an alkyl group having 1 to 3 carbon atoms, an aromatic group or a hydrogen atom, and is preferably a methyl group, a benzyl group or a hydrogen atom.

[0038] The structural unit (D) is preferably derived from a monomer represented by the following general formula (4).

[0039] In general formula (4), R 15 is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, o is an integer of 0 to 30, p is an integer of 0 to 30, and o+p is an integer of 2 to 30; R 15a is an alkyl group having 1 to 6 carbon atoms, an aromatic group, or a hydrogen atom. Here, o and p respectively represent the constituent ratio of the (C2H4O) repeating unit and the (C3H6O) repeating unit contained in general formula (4), and do not refer only to compounds consisting of blocks of (C2H4O) repeating units and blocks of (C3H6O) repeating units. The monomer represented by general formula (4) may be a compound in which the (C2H4O) repeating unit and the (C3H6O) repeating unit are arranged alternately or randomly, or may be a compound in which random portions and block portions are mixed.

[0040] In general formula (4), R 15 is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, etc. A hydrogen atom or a methyl group is preferred. That is, in the structural unit (D), the monomer represented by general formula (4) is (R 15 is a hydrogen atom or a methyl group).

[0041] In general formula (4), o is an integer of 0 to 30, p is an integer of 0 to 30, and o+p is 2 to 30; it is preferred that o is an integer of 0 to 25, p is an integer of 0 to 25, and o+p is 2 to 25, and it is particularly preferred that o is an integer of 0 to 20, p is an integer of 0 to 20, and o+p is 2 to 20.

[0042] In general formula (4), R 15a is an alkyl group having 1 to 3 carbon atoms, an aromatic group, or a hydrogen atom, and is preferably a methyl group, a benzyl group, or a hydrogen atom.

[0043] Specific examples of the monomer represented by general formula (3) include diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, tripropylene glycol mono(meth)acrylate, tetrapropylene glycol mono(meth)acrylate, and alkoxypolyalkylene glycol mono(meth)acrylates such as polypropylene glycol mono(meth)acrylate, polyethylene glycol-propylene glycol-mono(meth)acrylate, polyethylene glycol-tetramethylene glycol-mono(meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate, and methoxypolypropylene glycol mono(meth)acrylate. These can be used alone or in combination of two or more. Among these, tetraethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, tetrapropylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, methoxypolyethylene glycol mono(meth)acrylate, and methoxypolypropylene glycol mono(meth)acrylate are preferred.

[0044] The structural unit (D) contained in the polymer may be of one type, or may be of two or more types.

[0045] When the polymer contains the structural unit (D), the lower limit of the proportion of the structural unit (D) based on the monomer represented by general formula (3) (i.e., the proportion of the structural unit (D) in 100% by mass of all structural units constituting the polymer) is preferably 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 1.5% by mass or more. The upper limit of the proportion of the structural unit (D) based on the monomer represented by general formula (3) in the polymer is preferably 15% by mass or less, more preferably 12% by mass or less, and particularly preferably 10% by mass or less.

[0046] In terms of stabilizing the binder particles, the polymer preferably contains a constituent unit (E) derived from a polyfunctional (meth)acrylate monomer having five or fewer functionalities (i.e., a polyfunctional (meth)acrylate monomer having two to five functionalities) as a constituent unit derived from a (meth)acrylic acid ester. The constituent unit (E) is preferably a constituent unit derived from a monomer (compound) represented by the following general formula (5):

[0047] In general formula (5), R 16 are the same or different and each represents a hydrogen atom or a methyl group, and R 17 is an organic group having 2 to 100 carbon atoms and a valence of 5 or less, and m is an integer of 5 or less.

[0048] In general formula (5), m is preferably 2 to 5 (i.e., the structural unit (E) is a structural unit derived from a difunctional to pentafunctional (meth)acrylate), more preferably 3 to 5 (i.e., the structural unit (E) is a structural unit derived from a trifunctional to pentafunctional (meth)acrylate), and particularly preferably 3 to 4 (i.e., the structural unit (E) is a structural unit derived from a trifunctional to tetrafunctional (meth)acrylate).

[0049] In the structural unit (E), specific examples of structural units based on a monomer having two (meth)acryloyl groups include structural units derived from bifunctional (meth)acrylates such as triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, dioxane glycol di(meth)acrylate, bis(meth)acryloyloxyethyl phosphate, neopentyl glycol di(meth)acrylate, and 1,6-hexanediol diacrylate.

[0050] In the structural unit (E), specific examples of the monomer having three (meth)acryloyl groups include trifunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, trimethylolpropane EO-adduct tri(meth)acrylate, trimethylolpropane PO-adduct tri(meth)acrylate, pentaerythritol tri(meth)acrylate, 2,2,2-tris(meth)acryloyloxymethylethyl succinic acid, ethoxylated isocyanuric acid tri(meth)acrylate, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate, glycerin EO-adduct tri(meth)acrylate, glycerin PO-adduct tri(meth)acrylate, and tris(meth)acryloyloxyethyl phosphate. Among these, trifunctional (meth)acrylates selected from trimethylolpropane tri(meth)acrylate, trimethylolpropane EO adduct tri(meth)acrylate, and pentaerythritol tri(meth)acrylate are preferred.

[0051] In the structural unit (E), specific examples of the monomer having four (meth)acryloyl groups include tetrafunctional (meth)acrylates such as ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, and pentaerythritol EO-added tetra(meth)acrylate.

[0052] In the structural unit (E), a specific example of a monomer having five (meth)acryloyl groups is dipentaerythritol penta(meth)acrylate.

[0053] When the polymer contains the structural unit (E), the lower limit of its proportion (i.e., the proportion of the structural unit (E) in 100% by mass of all structural units constituting the polymer) is preferably 1% by mass or more, more preferably 3% by mass or more, and may be 5% by mass or more, or may be 5.2% by mass or more. The upper limit of the proportion of the structural unit (E) in the polymer is preferably 15% by mass or less, more preferably 12% by mass or less, and particularly preferably 10% by mass or less. This range is preferred in that it improves binding properties when used in an electrode.

[0054] The polymer preferably contains a structural unit (F) derived from a (meth)acrylic acid monomer, in that affinity with the active material is improved when used in an electrode.

[0055] Examples of the structural unit (F) include structural units derived from a compound selected from acrylic acid and methacrylic acid. The structural unit (F) contained in the polymer may be one type, or two or more types.

[0056] When the polymer contains the structural unit (F), the lower limit of its proportion (i.e., the proportion of the structural unit (F) in 100% by mass of all structural units constituting the polymer) is preferably 3% by mass or more, more preferably 4% by mass or more, and particularly preferably 5% by mass or more. The upper limit is preferably 15% by mass or less, more preferably 12% by mass or less, and particularly preferably 10% by mass or less.

[0057] In the polymer, the total proportion of the structural unit (A), the structural unit (B), the structural unit (C), the structural unit (D), the structural unit (E), and the structural unit (F) is preferably 85% by mass or more, more preferably 90% by mass or more, and particularly preferably 95% by mass or more, and may be 97% by mass or more, or even 100% by mass.

[0058] Furthermore, the polymer may contain a structural unit derived from a monomer having at least one selected from the group consisting of an epoxy group, a (blocked) isocyanate group, and a urethane group. The monomer is preferably a monomer having a reactive double bond. Furthermore, when the polymer contains a structural unit derived from the monomer, the polymer may contain one type of structural unit or two or more types of structural units.

[0059] Specific examples of the monomer having an epoxy group include allyl glycidyl ether, glycidyl acrylate, glycidyl methacrylate, and 4-hydroxybutyl acrylate glycidyl ether.

[0060] Specific examples of monomers having a (blocked) isocyanate group include 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-[0-(1'-methylpropylideneamino)carboxyamino]ethyl methacrylate, 2-[(3,5-dimethylpyrazolyl)carbonylamino]ethyl methacrylate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, and 2-(2-methacryloyloxyethyloxy)ethyl isocyanate.

[0061] Specific examples of monomers having a urethane group include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, phenyl glycidyl ether acrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer.

[0062] The lower limit of the proportion of structural units in the polymer derived from monomers having at least one selected from the group consisting of epoxy groups, (blocked) isocyanate groups, and urethane groups (i.e., the proportion of such structural units in 100% by mass of all structural units constituting the polymer) is preferably 0.5% by mass or more, more preferably 1% by mass or more, and particularly preferably 2% by mass or more. The upper limit of the proportion of structural units in the polymer derived from monomers having at least one selected from the group consisting of epoxy groups, (blocked) isocyanate groups, and urethane groups is preferably 10% by mass or less, more preferably 8% by mass or less, and particularly preferably 6% by mass or less.

[0063] In addition to the above, the polymer can contain, as a constituent unit derived from another monomer, a constituent unit derived from a monomer selected from fumaric acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, crotonnitrile, α-ethylacrylonitrile, α-cyanoacrylate, vinylidene cyanide, and fumaronitrile.

[0064] The polymer constituting the electrode binder of the present invention can be obtained by a conventional emulsion polymerization method, a soap-free emulsion polymerization method, or the like. Specifically, a composition containing a monomer, an emulsifier, a polymerization initiator, water, and optionally a dispersant, a chain transfer agent, a pH adjuster, etc., is emulsified in water by stirring at room temperature in a sealed container equipped with a stirrer and a heater under an inert gas atmosphere. Emulsification can be achieved by methods such as stirring, shearing, and ultrasonic waves, and a stirring blade or homogenizer can be used. The temperature is then raised while stirring to initiate polymerization, thereby obtaining a spherical polymer latex in which the polymer is dispersed in water. The monomer can be added during polymerization by batch charging, monomer dripping, pre-emulsion dripping, or the like, or by a combination of two or more of these methods. Pre-emulsion dripping refers to an addition method in which the monomer, emulsifier, water, etc. are first emulsified, and the resulting emulsion is then added dropwise.

[0065] The emulsifier used in the present invention is not particularly limited. The emulsifier is a surfactant, and this surfactant includes a reactive surfactant having a reactive group. Nonionic surfactants and anionic surfactants that are commonly used in emulsion polymerization methods can be used.

[0066] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alcohol ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene (di)styrenated phenyl ethers, polyoxyethylene polycyclic phenyl ethers, polyoxyalkylene alkyl ethers, sorbitan fatty acid esters, polyoxyethylene fatty acid esters, and polyoxyethylene sorbitan fatty acid esters. Examples of reactive nonionic surfactants include Latemul PD-420, 430, and 450 (manufactured by Kao Corporation), Adeka Reasop ER (manufactured by Adeka Corporation), Aqualon RN (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Antox LMA (manufactured by Nippon Nyukazai Co., Ltd.), and Antox EMH (manufactured by Nippon Nyukazai Co., Ltd.).

[0067] Examples of anionic surfactants include sulfate ester-type, carboxylic acid-type, or sulfonic acid-type metal salts, ammonium salts, triethanolammonium salts, and phosphate ester-type surfactants. Sulfate ester-type, sulfonic acid-type, and phosphate ester-type surfactants are preferred, with sulfate ester-type surfactants being particularly preferred. Representative examples of sulfate ester-type anionic surfactants include alkyl metal sulfates such as dodecyl sulfate, ammonium, or alkyl triethanolamine sulfate, polyoxyethylene alkyl ether metal sulfates such as polyoxyethylene dodecyl ether sulfate, polyoxyethylene isodecyl ether sulfate, and polyoxyethylene tridecyl ether sulfate, ammonium salts, or polyoxyethylene alkyl ether triethanolamine sulfate. Specific examples of sulfate ester-type reactive anionic surfactants include Latemul PD-104 and 105 (manufactured by Kao Corporation), Adeka Reasoap SR (manufactured by Adeka Corporation), Aqualon HS (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and Aqualon KH (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.). Preferred examples include sodium dodecyl sulfate, ammonium dodecyl sulfate, triethanolamine dodecyl sulfate, sodium dodecylbenzenesulfonate, and Latemul PD-104.

[0068] These nonionic surfactants and / or anionic surfactants may be used alone or in combination of two or more.

[0069] The reactive surfactant has a reactive double bond and undergoes a polymerization reaction with the monomer during polymerization. That is, the reactive surfactant acts as an emulsifier for the monomer during polymerization to produce the polymer, and after polymerization, the reactive surfactant is covalently bonded to and incorporated into a part of the polymer. Therefore, emulsion polymerization and dispersion of the produced polymer are good, and the electrode binder has excellent physical properties (flexibility, binding ability).

[0070] The amount of the emulsifier constituent units may be any amount generally used in emulsion polymerization, specifically, in the range of 0.01 to 25% by mass, preferably 0.05 to 20% by mass, and more preferably 0.1 to 20% by mass, relative to the amount of charged monomers (100% by mass).

[0071] The polymerization initiator used in the present invention is not particularly limited, and a polymerization initiator generally used in emulsion polymerization or suspension polymerization can be used. Emulsion polymerization is preferred. A water-soluble polymerization initiator is used in emulsion polymerization, and an oil-soluble polymerization initiator is used in suspension polymerization.

[0072] Specific examples of the water-soluble polymerization initiator include water-soluble polymerization initiators typified by persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; and water-soluble azo compound polymerization initiators such as 2-2'-azobis[2-(2-imidazolin-2-yl)propane] or its hydrochloride or sulfate, 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(2-methylpropanamidine) or its hydrochloride or sulfate, 3,3'-[azobis[(2,2-dimethyl-1-iminoethane-2,1-diyl)imino]]bis(propanoic acid), and 2,2'-[azobis(dimethylmethylene)]bis(2-imidazoline).

[0073] Preferred oil-soluble polymerization initiators include organic peroxides such as cumene hydroperoxide, benzoyl peroxide, acetyl peroxide, and t-butyl hydroperoxide, oil-soluble azo compound polymerization initiators such as azobisisobutyronitrile and 1,1'-azobis(cyclohexanecarbonitrile), and redox initiators. These polymerization initiators may be used alone or in combination of two or more.

[0074] The amount of the polymerization initiator used may be any amount generally used in emulsion polymerization or suspension polymerization, specifically, in the range of 0.01 to 10% by mass, preferably 0.01 to 5% by mass, and more preferably 0.02 to 3% by mass, relative to the amount of the charged monomer (100% by mass).

[0075] Specific examples of the chain transfer agent include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, and n-stearyl mercaptan, xanthogen compounds such as 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-methyl-2-pentene, dimethyl xanthogen disulfide, and diisopropyl xanthogen disulfide, and terpinolene, tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetramethylthiuram monosulfide. Examples of suitable chain transfer agents include thiuram compounds, phenolic compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, halogenated hydrocarbon compounds such as dichloromethane, dibromomethane and carbon tetrabromide, vinyl ethers such as α-benzyloxystyrene, α-benzyloxyacrylonitrile and α-benzyloxyacrylamide, triphenylethane, pentaphenylethane, acrolein, methacrolein, thioglycolic acid, thiomalic acid, and 2-ethylhexyl thioglycolate, and these may be used alone or in combination of two or more. The amount of these chain transfer agents is not particularly limited, but is typically 0 to 5 parts by mass per 100 parts by mass of the charged monomers.

[0076] In producing the polymer, the polymerization temperature and polymerization time are not particularly limited. They can be appropriately selected depending on the type of polymerization initiator used, etc., but generally, the polymerization temperature is 20 to 100°C, and the polymerization time is 0.5 to 100 hours.

[0077] The electrode binder of the present invention contains a polymer, but other substances such as water or an emulsifier may be contained inside the polymer or attached to the outside. The amount of the substance contained inside or attached to the outside is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less, relative to 100 parts by mass of the polymer.

[0078] <2. Electrode Binder Composition> The binder composition of the present invention contains the binder of the present invention described above in the section "1. Electrode Binder" together with a solvent, and the binder may be dispersed in the solvent. The solvent can be water or an organic solvent. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, and amyl alcohol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; ethers such as diethyl ether, dioxane, and tetrahydrofuran; amide-based polar organic solvents such as N,N-dimethylformamide and N-methyl-2-pyrrolidone (NMP); and aromatic hydrocarbons such as toluene, xylene, chlorobenzene, ortho-dichlorobenzene, and para-dichlorobenzene.

[0079] The electrode binder composition of the present invention is preferably an aqueous binder composition in which the binder is dispersed in water.

[0080] The electrode binder composition of the present invention may be an emulsion using an emulsion produced when obtaining the binder.

[0081] The content of the binder in the electrode binder composition of the present invention is not particularly limited, but the binder is preferably contained so that the concentration of the solid content other than the solvent of the binder (hereinafter, may be simply referred to as "solid content") is 0.2 to 80 mass %, more preferably 0.5 to 70 mass %, and particularly preferably 0.5 to 60 mass %.

[0082] The pH of the electrode binder composition of the present invention can be adjusted, if necessary, by using a base as a pH adjuster. Specific examples of bases include alkali metal (Li, Na, K, Rb, Cs) hydroxides, ammonia, inorganic ammonium compounds, and organic amine compounds. The pH range is 2 to 11, preferably 3 to 10, and more preferably 4 to 9.

[0083] The electrode binder composition of the present invention may contain polyacrylic acid or the like.

[0084] 3. Electrode The electrode of the present invention comprises an electrode material layer on a current collector.

[0085] Known current collectors can be used for the electrodes of the present invention. Specifically, metals such as aluminum, nickel, stainless steel, gold, platinum, and titanium are used for the positive electrode. Metals such as copper, nickel, stainless steel, gold, platinum, titanium, and aluminum are used for the negative electrode.

[0086] The electrode material layer contains at least an active material and the binder of the present invention described in the above section "1. Electrode Binder," and may further contain a conductive additive. The electrode material of the present invention is preferably produced using the electrode binder composition of the present invention described in the section "2. Electrode Binder Composition," which contains the electrode binder of the present invention together with a solvent. Specifically, in a lithium-ion battery, the positive electrode material used in the positive electrode contains a positive electrode active material and the electrode binder of the present invention and may further contain a conductive additive. The negative electrode material used in the negative electrode contains a negative electrode active material, the electrode binder of the present invention, and may further contain a conductive additive. In an electric double layer capacitor (electrochemical capacitor), the positive electrode material used in the positive electrode contains activated carbon as the active material and the electrode binder of the present invention and may further contain a conductive additive. The negative electrode material used in the negative electrode contains activated carbon as the active material and the electrode binder of the present invention and may further contain a conductive additive.

[0087] The positive electrode active material used in lithium-ion batteries is an alkali metal-containing composite oxide having one of the following compositions: AMO2, AM2O4, A2MO3, or AMBO4. A is an alkali metal, and M is a single or two or more transition metals, some of which may contain non-transition metals. B is P, Si, or a mixture thereof. The positive electrode active material is preferably a powder, with a particle size of preferably 50 microns or less, more preferably 20 microns or less. These active materials have an electromotive force of 3 V (vs. Li / Li+) or more.

[0088] Preferred examples of the positive electrode active material used in lithium ion batteries include LixCoO2, LixNiO2, LixMnO2, LixCrO2, LixFeO2, and LixCoaMn 1-a O2, LixCoaNi 1-a O2, LixCoaCr 1-a O2, LixCoaFe 1-a O2, LixCoaTi 1-a O2, LixMnaNi 1-a O2, LixMnaCr 1-a O2, LixMnaFe 1-a O2, LixMnaTi 1-a O2, LixNiaCr 1-a O2, LixNiaFe 1-a O2, LixNiaTi 1-a O2, LixCraFe 1-a O2, LixCraTi 1-a O2, LixFeaTi 1-a O2, LixCobMncNi 1-b-C O2, LixNiaCobAlcO2, LixCrbMncNi 1-b-C O2, LixFebMncNi 1-b-C O2, LixTibMncNi 1-b-C O2, LixMn2O4, LixMndCo 2-d O4, LixMndNi 2-d O4, LixMndCr 2-d O4, LixMndFe 2-d O4, LixMndTi 2-d O4, LiyMnO3, LiyMneCo 1-e O3, LiyMneNi 1-e O3, LiyMneFe 1-e O3, LiyMneTi 1-e O3, LixCoPO4, LixMnPO4, LixNiPO4, LixFePO4, LixCofMn 1-f PO4, LixCofNi 1-f PO4, LixCofFe 1-f PO4, LixMnfNi 1-f PO4, LixMnfFe1-f PO4, LixNifFe 1-f PO4, LiyCoSiO4, LiyMnSiO4, LiyNiSiO4, LiyFeSiO4, LiyCogMn 1-g SiO4, LiyCogNi 1-g SiO4, LiyCogFe 1-g SiO4, LiyMngNi 1-g SiO4, LiyMngFe 1-g SiO4, LiyNigFe 1-g SiO4, LiyCoPhSi 1-h O4, LiyMnPhSi 1-h O4, LiyNiPhSi 1-h O4, LiyFePhSi 1-h O4, LiyCogMn 1-g PhSi 1-h O4, LiyCogNi 1-g PhSi 1-h O4, LiyCogFe 1-g PhSi 1-h O4, LiyMngNi 1-g PhSi 1-h O4, LiyMngFe 1-g PhSi 1-h O4, LiyNigFe 1-g PhSi 1-h Examples of suitable lithium-containing composite oxides include lithium-containing composite oxides such as SiO4 (where x = 0.01 to 1.2, y = 0.01 to 2.2, a = 0.01 to 0.99, b = 0.01 to 0.98, c = 0.01 to 0.98, and b + c = 0.02 to 0.99, d = 1.49 to 1.99, e = 0.01 to 0.99, f = 0.01 to 0.99, g = 0.01 to 0.99, and h = 0.01 to 0.99).

[0089] Among the above-mentioned preferred positive electrode active materials for use in lithium ion batteries, more preferred positive electrode active materials are specifically LixCoO2, LixNiO2, LixMnO2, LixCrO2, and LixCoaNi. 1-a O2, LixMnaNi 1-a O2, LixCobMncNi 1-b-CO2, LixNiaCobAlcO2, LixMn2O4, LiyMnO3, LiyMneFe 1-e O3, LiyMneTi 1-e O3, LixCoPO4, LixMnPO4, LixNiPO4, LixFePO4, LixMnfFe 1-f PO4 (where x = 0.01 to 1.2, y = 0.01 to 2.2, a = 0.01 to 0.99, b = 0.01 to 0.98, c = 0.01 to 0.98, and b + c = 0.02 to 0.99, d = 1.49 to 1.99, e = 0.01 to 0.99, and f = 0.01 to 0.99. The values ​​of x and y increase or decrease with charge and discharge.)

[0090] The negative electrode active material used in lithium-ion batteries is a carbon material (natural graphite, artificial graphite, amorphous carbon, etc.) having a structure (porous structure) capable of absorbing and releasing lithium ions, or a powder made of a metal such as lithium, aluminum-based compounds, tin-based compounds, silicon-based compounds, or titanium-based compounds such as niobium titanium-based oxides, capable of absorbing and releasing lithium ions. The particle size is preferably 10 nm or more and 100 μm or less, more preferably 20 nm or more and 20 μm or less. A mixed active material of a metal and a carbon material may also be used. It is desirable to use a negative electrode active material with a porosity of about 70%.

[0091] Examples of carbon materials include graphite, low-crystalline carbon (soft carbon, hard carbon), carbon black (ketjen black, acetylene black, channel black, lamp black, oil furnace black, thermal black, etc.), fullerene, carbon nanotube, carbon nanofiber, carbon nanohorn, carbon fibril, coke, mesocarbon microbeads (MCMB), mesophase pitch-based carbon fiber, phenolic resin baked body, polyacrylonitrile-based carbon fiber, and the like, and graphite is preferred.

[0092] Silicon-based compounds include elemental Si, alloys with Si, oxides containing Si, and carbides containing Si, and examples thereof include Si, SiB4, SiB6, Mg2Si, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu5Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, and SiO x (0<x≦2), SnSiO x , LiSiO, and SiO x (0<x≦2) is preferred, and examples thereof include silicon monoxide (SiO).

[0093] When a silicon-based compound and another active material (such as a carbon material) are used in combination in the active material, they are preferably contained as follows. The content of the silicon-based compound relative to the total amount of active material (100% by mass) is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and particularly preferably 20% by mass or more, and the upper limit is preferably 80% by mass or less, more preferably 60% by mass or less, and particularly preferably 40% by mass or less. The content of the other active material (such as a carbon material) relative to the total amount of active material (100% by mass) is preferably 20% by mass or more, more preferably 40% by mass or more, and particularly preferably 60% by mass or more, and the upper limit is preferably 99% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, and particularly preferably 80% by mass or less.

[0094] An example of an active material used in an electric double layer capacitor (electrochemical capacitor) is activated carbon. Generally, activated carbon refers to an activated carbonized material, and commercially available activated carbon or activated carbon produced according to a known production method may be used. Activated carbon can be produced by carbonizing raw materials such as wood, coconut shells, pulp waste liquid, coal, heavy oil, and phenolic resin, and then activating the resulting carbonized material.

[0095] Activation can be performed by any known activation method, such as gas activation or chemical activation. In gas activation, the carbonized material is activated by contacting it with a gas such as steam, carbon dioxide, or oxygen under heating. In chemical activation, the carbonized material is activated by heating it in contact with a known activation chemical. Examples of activation chemicals include zinc chloride, phosphoric acid, and / or alkaline compounds (metal hydroxides such as sodium hydroxide). It is preferable to use activated carbon activated with steam (referred to as steam-activated carbon in this application) and / or activated carbon activated with alkali (referred to as alkali-activated activated carbon in this application).

[0096] The content of the active material in the electrode material layer is not particularly limited, and may be, for example, 99.9 to 50 mass%, more preferably 99.5 to 70 mass%, and even more preferably 99 to 85 mass%, relative to the electrode material layer (100 mass%). The active material may be used alone or in combination of two or more types.

[0097] The content of the binder of the present invention in the electrode material layer is not particularly limited, and may be, for example, 0.01 to 20 parts by mass, more preferably 0.05 to 15 parts by mass, and even more preferably 0.1 to 10 parts by mass, relative to 100 parts by mass of the active material.

[0098] When a conductive additive is used, a known conductive additive can be used, and examples thereof include conductive carbon black such as graphite, furnace black, acetylene black, and ketjen black, carbon fibers such as carbon nanotubes (CNT), and metal powders. These conductive additives may be used alone or in combination of two or more.

[0099] When a conductive additive is used, the content of the conductive additive is not particularly limited, but is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, relative to 100 parts by mass of the active material. When a conductive additive is contained in the positive electrode material, the lower limit of the content of the conductive additive can be typically 0.05 parts by mass or more, 0.1 parts by mass or more, 0.2 parts by mass or more, 0.5 parts by mass or more, or 2 parts by mass or more.

[0100] The electrode material of the present invention may contain a thickener as needed. The type of thickener is not particularly limited, but preferred examples include sodium salts and ammonium salts of cellulose compounds, polyvinyl alcohol, polyacrylic acid and its salts, etc.

[0101] Examples of sodium salts or ammonium salts of cellulose compounds include sodium salts or ammonium salts of alkylcelluloses in which cellulose polymers are substituted with various derivative groups. Specific examples include sodium salts, ammonium salts, and triethanolammonium salts of methyl cellulose, methyl ethyl cellulose, ethyl cellulose, and carboxymethyl cellulose (CMC). Sodium salts or ammonium salts of carboxymethyl cellulose are particularly preferred. These thickeners may be used alone or in combination of two or more in any ratio.

[0102] When a thickener is used, the content of the thickener is not particularly limited, but is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, relative to 100 parts by mass of the active material. When a thickener is contained, the lower limit of the content of the thickener is typically 0.05 parts by mass or more, 0.1 parts by mass or more, 0.2 parts by mass or more, 0.5 parts by mass or more, or 1 part by mass or more, for example.

[0103] The method for producing the electrode is not particularly limited, and a common method can be used, such as applying the electrode material uniformly to an appropriate thickness onto the surface of a current collector (metal electrode substrate) by a doctor blade method, an applicator method, a silk screen method, or the like.

[0104] The electrode material of the present invention may contain water to form a slurry. The water is not particularly limited, and commonly used water can be used. Specific examples include tap water, distilled water, ion-exchanged water, and ultrapure water. Among these, distilled water, ion-exchanged water, and ultrapure water are preferred.

[0105] When the electrode material of the present invention is used in the form of a slurry, the solid content of the slurry is preferably 10 to 90 mass %, more preferably 20 to 85 mass %, and particularly preferably 20 to 80 mass %.

[0106] When the electrode material of the present invention is used in the form of a slurry, the proportion of the polymer amount in the solid content of the slurry is preferably 0.1 to 15 mass%, more preferably 0.2 to 10 mass%, and particularly preferably 0.3 to 7 mass%.

[0107] The method for preparing the electrode material is not particularly limited, and the positive electrode active material or negative electrode active material, the electrode binder of the present invention, the conductive additive, water, etc. may be dispersed using a conventional stirrer, disperser, kneader, planetary ball mill, homogenizer, etc. In order to increase the efficiency of dispersion, heating may be performed within a range that does not affect the materials. The electrode binder may be the electrode binder composition of the present invention described in the section "2. Electrode binder composition," which contains the electrode binder of the present invention together with a solvent.

[0108] For example, in the doctor blade method, the electrode slurry is applied to a metal electrode substrate and then uniformly applied to an appropriate thickness using a blade with a predetermined slit width. After the active material is applied to the electrode, the electrode is dried, for example, with hot air at 100°C or in a vacuum at 80°C to remove excess organic solvent and water. The dried electrode is press-molded using a press device to produce an electrode material. After pressing, the electrode may be heat-treated again to remove water, solvent, emulsifier, etc.

[0109] <4. Electricity storage device> The electricity storage device of the present invention is characterized by comprising the positive electrode, negative electrode, and electrolyte (including an inorganic solid electrolyte) described above in the section "3. Electrodes." That is, the electrodes used in the electricity storage device of the present invention contain the electrode material of the present invention, i.e., the electrode binder of the present invention. Details of the electrode of the present invention are as described above. Note that, for the electricity storage device of the present invention, it is sufficient that at least one of the positive electrode and the negative electrode uses an electrode material containing the electrode binder of the present invention, and a known electrode can be used for the electrode that does not use the electrode material containing the electrode binder of the present invention.

[0110] The electrolyte is not particularly limited, and a known electrolytic solution can be used. Specific examples of the electrolytic solution include a solution containing a lithium salt compound and a solvent, or a room-temperature molten salt. The electrolyte and the solvent may each be used alone or in combination of two or more.

[0111] Specific examples of lithium salt compounds include, but are not limited to, LiBF, LiPF, LiClO, LiCFSO, LiN(CFSO), LiN(CFSO), LiN[CFSC(CFSO)].

[0112] Examples of electrolytes other than lithium salt compounds include tetraethylammonium tetrafluoroborate, triethylmonomethylammonium tetrafluoroborate, and tetraethylammonium hexafluorophosphate.

[0113] Examples of the solvent used in the electrolytic solution include organic solvents.

[0114] Examples of the organic solvent include aprotic organic solvents. Specific examples of such organic solvents include propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, fluoroethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, dipropyl carbonate, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propylnitrile, anisole, acetate esters, propionate esters, and straight-chain ethers such as diethyl ether. Two or more of these organic solvents may be used in combination.

[0115] Room-temperature molten salts are also called ionic liquids, and are "salts" composed only of ions (anions and cations), and liquid compounds in particular are called ionic liquids.

[0116] In the present invention, the room-temperature molten salt refers to a salt that is at least partially liquid at room temperature, and room temperature refers to the temperature range in which a battery is generally expected to operate, with an upper limit of about 120°C, or in some cases about 80°C, and a lower limit of about −40°C, or in some cases about −20°C.

[0117] Known cationic species of room-temperature molten salts include quaternary ammonium organic cations of pyridine, aliphatic amine, and alicyclic amine. Examples of quaternary ammonium organic cations include imidazolium ions such as dialkylimidazolium and trialkylimidazolium, tetraalkylammonium ions, alkylpyridinium ions, pyrazolium ions, pyrrolidinium ions, and piperidinium ions. Imidazolium ions are particularly preferred.

[0118] Examples of tetraalkylammonium ions include, but are not limited to, trimethylethylammonium ion, trimethylethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, tetrapentylammonium ion, and triethylmethylammonium ion.

[0119] Examples of alkylpyridinium ions include, but are not limited to, an N-methylpyridinium ion, an N-ethylpyridinium ion, an N-propylpyridinium ion, an N-butylpyridinium ion, a 1-ethyl-2-methylpyridinium ion, a 1-butyl-4-methylpyridinium ion, and a 1-butyl-2,4-dimethylpyridinium ion.

[0120] Examples of imidazolium ions include, but are not limited to, a 1,3-dimethylimidazolium ion, a 1-ethyl-3-methylimidazolium ion, a 1-methyl-3-ethylimidazolium ion, a 1-methyl-3-butylimidazolium ion, a 1-butyl-3-methylimidazolium ion, a 1,2,3-trimethylimidazolium ion, a 1,2-dimethyl-3-ethylimidazolium ion, a 1,2-dimethyl-3-propylimidazolium ion, and a 1-butyl-2,3-dimethylimidazolium ion.

[0121] The anion species of room temperature molten salts include halide ions such as chloride ions, bromide ions, and iodide ions, perchlorate ions, thiocyanate ions, tetrafluoroborate ions, nitrate ions, and AsF6 - , PF6 - and organic acid ions such as stearylsulfonate ion, octylsulfonate ion, dodecylbenzenesulfonate ion, naphthalenesulfonate ion, dodecylnaphthalenesulfonate ion, and 7,7,8,8-tetracyano-p-quinodimethane ion.

[0122] The room temperature molten salt may be used alone or in combination of two or more.

[0123] Various additives can be used in the electrolyte solution as needed. Examples of additives include flame retardants, flame retardants, positive electrode surface treatment agents, negative electrode surface treatment agents, and overcharge inhibitors. Examples of flame retardants and flame retardants include brominated epoxy compounds, phosphazene compounds, halides such as tetrabromobisphenol A and chlorinated paraffins, antimony trioxide, antimony pentoxide, aluminum hydroxide, magnesium hydroxide, phosphate esters, polyphosphates, and zinc borate. Examples of positive electrode surface treatment agents include inorganic compounds such as carbon and metal oxides (e.g., MgO and ZrO2), and organic compounds such as ortho-terphenyl. Examples of negative electrode surface treatment agents include vinylene carbonate, fluoroethylene carbonate, and polyethylene glycol dimethyl ether. Examples of overcharge inhibitors include biphenyl and 1-(p-tolyl)adamantane.

[0124] The method for manufacturing the electricity storage device of the present invention is not particularly limited, and it can be manufactured by a known method using a positive electrode, a negative electrode, an electrolyte, and, if necessary, a separator. For example, in the case of a coin-shaped device, the positive electrode, and, if necessary, a separator and a negative electrode are inserted into an outer can. An electrolyte solution is poured into the can and impregnated. Thereafter, the device is joined to a sealing body by tab welding or the like, and the sealing body is sealed and crimped to obtain an electricity storage device. The shape of the electricity storage device is not limited, and examples include a coin shape, a cylindrical shape, and a sheet shape.

[0125] The separator prevents the positive electrode and the negative electrode from coming into direct contact with each other, causing a short circuit inside the battery, and may be made of a known material. Specific examples of the separator include porous polymer films such as polyolefins, and paper. Films such as polyethylene and polypropylene are preferred as porous polymer films because they are less affected by the electrolyte.

[0126] Specific embodiments for carrying out the present invention will be described below with reference to examples, but the present invention is not limited to the following examples as long as they do not deviate from the gist of the present invention.

[0127] <Measurement of average particle size> The average particle size of the polymer was measured under the following conditions. (Measurement device) Particle size distribution measurement device using dynamic light scattering: Zetasizer Nano (Spectris Inc.) (Measurement conditions) 1. 50 μL of the synthesized emulsion solution was sampled. 2. 700 μL of ion-exchanged water was added three times to the sampled emulsion solution to dilute it. 3. 2100 μL of liquid was withdrawn from the diluted solution. 4. 700 μL of ion-exchanged water was added to the remaining 50 μL sample, diluted, and measured.

[0128] In the present examples and comparative examples, the peel strength was measured to evaluate the electrodes, and the cycle test was performed to evaluate the coin batteries in the following experiments.

[0129] [Peel Strength] <Preparation of Sample for Measuring 180-Degree Peel Strength> A test piece was prepared by cutting a negative electrode so that the long side was 60 mm and the short side was 10 mm. A 200 mm piece of cellophane tape (Nichiban Co., Ltd.) was cut out onto one end of the test piece, and the cut edge was used to pinch the end by about 10 mm. A handle of about 90 mm was attached to the remaining part of the test piece by bonding the cellophane tape together.

[0130] <180-degree peel test> The negative electrode mixture layer side was fixed to a SUS plate using double-sided tape (Nichiban Co., Ltd.), and a 180-degree peel test was performed using a universal testing machine (Toyo Seiki Seisakusho, E0-L Co., Ltd.) by pulling the handle to peel off the copper foil (movement distance 100 mm, 50 mm / min). The peel strength was calculated as the average of three trials, excluding the measured value from immediately after the start of the measurement to about 10 mm.

[0131] [Evaluation of characteristics of prepared batteries] To evaluate the characteristics of the prepared coin batteries, charge / discharge efficiency was measured. <Measurement of charge / discharge efficiency 1> (Measurement device) Charge / discharge evaluation device: TOSCAT-3100 (Toyo Systems Co., Ltd.) (Measurement method) The coin batteries prepared in Examples 1 and 2 and Comparative Example 3 were discharged at 0.2 C by constant current-constant voltage discharge. The final current was equivalent to 0.04 C. After discharge, the batteries were allowed to rest for 10 minutes. Next, they were charged to 1.2 V by constant current charging at 0.2 C. This operation constitutes one cycle, and 50 charge / discharge cycles were performed. The discharge capacity at the 50th cycle was divided by the discharge capacity at the first cycle to obtain a percentage, which was defined as the discharge capacity retention rate (%). The evaluation results are shown in Table 3.

[0132] <Measurement of Charge / Discharge Efficiency 2> (Measurement Device) Charge / Discharge Evaluation Device: TOSCAT-3100 (Toyo Systems Co., Ltd.) (Measurement Method) The coin batteries produced in Examples 1 to 4 and Comparative Examples 1 and 2 were each charged to 4.2 V at 0.2 C by constant current-constant voltage charging. The final voltage was equivalent to 0.04 C. After charging, the batteries were left to rest for 10 minutes. Next, they were discharged to 2.7 V by constant current discharging at 0.2 C. This operation constitutes one cycle, and five cycles of charge / discharge operations were carried out. The discharge capacity at the fifth cycle was divided by the discharge capacity at the first cycle to obtain a percentage, which was defined as the discharge capacity retention rate (%). The evaluation results are shown in Table 4.

[0133] [Synthesis Example 1] A beaker was charged with 197.79 g of n-butyl acrylate, 145.69 g of benzyl methacrylate, 5.45 g of acrylic acid, 15.27 g of methacrylic acid, 14.51 g of polyethylene glycol monomethacrylate (molecular weight: approximately 174), 21.12 g of trimethylolpropane trimethacrylate, 0.96 g of 6-(4-vinylbenzyl-n-propyl)amino-1,3,5-triazine-2,4-dithiol, 6.40 g of sodium dodecyl sulfate as an emulsifier, 1.60 g of polyoxyethylene styrenated phenyl ether, and 200 g of ion-exchanged water, and the mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. 400 g of ion-exchanged water was placed in a reaction vessel equipped with a stirrer and heated to 58°C under a nitrogen atmosphere. 0.87 g of t-butyl hydroperoxide as a polymerization initiator and 0.56 g of L-ascorbic acid as a reducing agent were added, and the emulsion was added over 220 minutes. After the addition of the emulsion, polymerization was continued for an additional hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.9 to 7.9 using a 28% aqueous ammonia solution to obtain Binder Composition A (polymerization conversion rate of 99% or more, solids concentration of 39.9 wt%) as an emulsion solution. The average particle size of the resulting polymer was 0.196 μm. The mass percentage of the polymer is shown in Table 1.

[0134] [Synthesis Example 2] In a beaker, 197.79 g of n-butyl acrylate, 145.69 g of benzyl methacrylate, 5.45 g of acrylic acid, 15.27 g of methacrylic acid, 14.51 g of polyethylene glycol monomethacrylate (molecular weight approximately 174), 21.12 g of trimethylolpropane trimethacrylate, 0.96 g of methacryloxypolypropylene glycol phosphate, 6.40 g of sodium dodecyl sulfate as an emulsifier, 1.60 g of polyoxyethylene styrenated phenyl ether, and 200 g of ion-exchanged water were placed, and the mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. 400 g of ion-exchanged water was placed in a reaction vessel equipped with a stirrer, heated to 58 ° C. under a nitrogen atmosphere, and 0.87 g of t-butyl hydroperoxide as a polymerization initiator and 0.56 g of L-ascorbic acid as a reducing agent were added, and the emulsion was added over 220 minutes. After the addition of the emulsion, the mixture was further polymerized for 1 hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 3.0 to 7.9 using a 28% aqueous ammonia solution to obtain a binder composition B (polymerization conversion rate of 99% or more, solid content concentration of 40.0 wt%) as an emulsion solution. The average particle size of the obtained polymer was 0.219 μm. The mass % of the polymer is shown in Table 1.

[0135] [Synthesis Example 3] In a beaker, 197.79 g of n-butyl acrylate, 145.69 g of benzyl methacrylate, 5.45 g of acrylic acid, 15.27 g of methacrylic acid, 14.51 g of polyethylene glycol monomethacrylate (molecular weight approximately 174), 21.12 g of trimethylolpropane trimethacrylate, 0.96 g of methacryloyloxyethyl phosphate, 6.40 g of sodium dodecyl sulfate as an emulsifier, 1.60 g of polyoxyethylene styrenated phenyl ether, and 200 g of ion-exchanged water were placed, and the mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. 400 g of ion-exchanged water was placed in a reaction vessel equipped with a stirrer, heated to 58 ° C. under a nitrogen atmosphere, and 0.87 g of t-butyl hydroperoxide as a polymerization initiator and 0.56 g of L-ascorbic acid as a reducing agent were added, and the emulsion was added over 220 minutes. After the addition of the emulsion, the mixture was further polymerized for 1 hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.3 to 8.0 using a 28% aqueous ammonia solution to obtain a binder composition C (polymerization conversion rate of 99% or more, solid content concentration of 40.1 wt%) as an emulsion solution. The average particle size of the obtained polymer was 0.193 μm. The mass % of the polymer is shown in Table 1.

[0136] [Example 4] In a beaker, 69.23 g of n-butyl acrylate, 145.69 g of benzyl methacrylate, 128.60 g of n-lauryl methacrylate, 5.45 g of acrylic acid, 15.27 g of methacrylic acid, 14.51 g of methoxypolyethylene glycol monomethacrylate (molecular weight approximately 496), 21.12 g of 1,6-hexanediol diacrylate, 0.96 g of methacryloxypolypropylene glycol phosphate, 6.40 g of sodium dodecyl sulfate as an emulsifier, 1.60 g of polyoxyethylene styrenated phenyl ether, and 200 g of ion-exchanged water were placed, and the mixture was thoroughly stirred using an ultrasonic homogenizer to prepare an emulsion. 400 g of ion-exchanged water was placed in a reaction vessel equipped with a stirrer, heated to 58 ° C. under a nitrogen atmosphere, and 0.87 g of t-butyl hydroperoxide as a polymerization initiator and 0.56 g of L-ascorbic acid as a reducing agent were added, and the emulsion was added over 220 minutes. After the addition of the emulsion, the mixture was polymerized for another hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 3.0 to 8.2 using a 28% aqueous ammonia solution to obtain Binder Composition D (polymerization conversion rate of 99% or more, solids concentration of 40.9 wt%) as an emulsion solution. The average particle size of the obtained polymer was 0.245 μm. The mass % of the polymer is shown in Table 1.

[0137] Comparative Synthesis Example 1: 197.79 g of n-butyl acrylate, 146.65 g of benzyl methacrylate, 5.45 g of acrylic acid, 15.27 g of methacrylic acid, 14.51 g of polyethylene glycol monomethacrylate (molecular weight approximately 174), 21.12 g of trimethylolpropane trimethacrylate, 6.40 g of sodium dodecyl sulfate as an emulsifier, 1.60 g of polyoxyethylene styrenated phenyl ether, and 200 g of ion-exchanged water were placed in a beaker and thoroughly stirred using an ultrasonic homogenizer to form an emulsion. 400 g of ion-exchanged water was placed in a reaction vessel equipped with a stirrer and heated to 58°C under a nitrogen atmosphere. 0.87 g of t-butyl hydroperoxide as a polymerization initiator and 0.56 g of L-ascorbic acid as a reducing agent were added, and the emulsion was added over 220 minutes. After the addition of the emulsion, polymerization was continued for another hour, followed by cooling. After cooling, the pH of the polymer solution was adjusted from 3.0 to 8.0 using a 28% aqueous ammonia solution to obtain a binder composition E (polymerization conversion rate 99% or more, solid content concentration 40.2 wt%) as an emulsion solution. The average particle size of the obtained polymer was 0.210 μm. The mass % of the polymer is shown in Table 1.

[0138] Comparative Synthesis Example 2: 69.23 g of n-butyl acrylate, 146.69 g of benzyl methacrylate, 128.60 g of n-lauryl methacrylate, 5.45 g of acrylic acid, 15.27 g of methacrylic acid, 14.51 g of polyethylene glycol monomethacrylate (molecular weight approximately 439), 21.12 g of 1,6-hexanediol diacrylate, 6.40 g of sodium dodecyl sulfate as emulsifier, 1.60 g of polyoxyethylene styrenated phenyl ether, and 200 g of ion-exchanged water were placed in a beaker and thoroughly stirred using an ultrasonic homogenizer to form an emulsion. 400 g of ion-exchanged water was placed in a reaction vessel equipped with a stirrer and heated to 58°C under a nitrogen atmosphere. 0.87 g of t-butyl hydroperoxide as a polymerization initiator and 0.56 g of L-ascorbic acid as a reducing agent were added, and the emulsion was added over 220 minutes. After the addition of the emulsion, polymerization was continued for another hour, followed by cooling. After cooling, the pH of the polymer solution was adjusted from 3.2 to 8.0 using a 28% aqueous ammonia solution to obtain a binder composition F (polymerization conversion rate 99% or more, solids concentration 38.9 wt%) as an emulsion solution. The average particle size of the obtained polymer was 0.197 μm. The mass % of the polymer is shown in Table 1.

[0139] Unit: mass%

[0140] <Electrode Preparation Examples> [Electrode Preparation Example 1] 65.4 parts by mass of graphite and 30 parts by mass of SiO as negative electrode active materials were added to 1 part by mass of acetylene black, 0.1 parts by mass of CNT (manufactured by OCSiAL), and 2 parts by mass of carboxymethylcellulose sodium salt as conductive additives, and 5 parts by mass of the solid content of binder composition A obtained in Example Synthesis Example 1 of the binder composition. Water was further added so that the solid content concentration of the slurry became 35% by mass, and the mixture was thoroughly mixed using a planetary mill to obtain a negative electrode slurry. The obtained negative electrode slurry was applied to a copper current collector having a thickness of 10 μm using a Baker-type applicator with a 100 μm gap, dried at 110° C. in a vacuum for 10 hours or more, and then pressed using a roll press to obtain an electrode with a density of 1.6 g / cm. 3 A sample for measuring 180-degree peel strength was prepared, and a 180-degree peel test was carried out. The results are shown in Example 1 of Table 2.

[0141] [Electrode Preparation Example 2] An electrode was prepared in the same manner as in Electrode Example 1, except that 65.4 parts by mass of graphite and 30 parts by mass of SiO were used as negative electrode active materials, and 1 part by mass of acetylene black, 0.1 part by mass of CNT (manufactured by OCSiAL), 2 parts by mass of carboxymethyl cellulose sodium salt were used as conductive additives, and 5 parts by mass of the solid content of Binder Composition B obtained in Synthesis Example 2 of the Binder Composition were added, and water was further added so that the solid content concentration of the slurry became 35% by mass, and the mixture was thoroughly mixed using a planetary mill to obtain a negative electrode slurry. The electrode had a density of 1.6 g / cm. 3 A sample for measuring 180-degree peel strength was prepared, and a 180-degree peel test was carried out. The results are shown in Example 2 in Table 2.

[0142] [Electrode Preparation Example 3] An electrode was prepared in the same manner as in Electrode Example 1, except that 65.4 parts by mass of graphite and 30 parts by mass of SiO were used as negative electrode active materials, 1 part by mass of acetylene black, 0.1 part by mass of CNT (manufactured by OCSiAL), and 2 parts by mass of carboxymethyl cellulose sodium salt were used as conductive additives, and 5 parts by mass of the solid content of Binder Composition C obtained in Synthesis Example 3 of the Binder Composition were added, and water was further added so that the solid content concentration of the slurry became 35% by mass, and the mixture was thoroughly mixed using a planetary mill to obtain a negative electrode slurry. Electrode density: 1.6 g / cm 3 A sample for measuring 180-degree peel strength was prepared, and a 180-degree peel test was carried out. The results are shown in Example 3 of Table 2.

[0143] [Electrode Preparation Example 4] An electrode was prepared in the same manner as in Electrode Example 1, except that 65.4 parts by mass of graphite and 30 parts by mass of SiO were used as negative electrode active materials, 1 part by mass of acetylene black as a conductive additive, 0.1 part by mass of CNT (manufactured by OCSiAL), 2 parts by mass of carboxymethyl cellulose sodium salt, and 5 parts by mass of the solid content of Binder Composition D obtained in Synthesis Example 4 of the Binder Composition were added, and water was further added so that the solid content concentration of the slurry became 35% by mass, and the mixture was thoroughly mixed using a planetary mill to obtain a negative electrode slurry. The electrode had a density of 1.6 g / cm. 3A sample for measuring 180-degree peel strength was prepared, and a 180-degree peel test was carried out. The results are shown in Example 4 in Table 2.

[0144] [Comparative Electrode Preparation Example 1] An electrode was prepared in the same manner as in Electrode Example 1, except that 65.4 parts by mass of graphite and 30 parts by mass of SiO were used as negative electrode active materials, 1 part by mass of acetylene black, 0.1 part by mass of CNT (manufactured by OCSiAL), and 2 parts by mass of carboxymethylcellulose sodium salt were used as conductive additives, and 5 parts by mass of the solid content of Binder Composition E obtained in Comparative Synthesis Example 1 of the Binder Composition were added, and water was further added so that the solid content concentration of the slurry became 35% by mass, and the mixture was thoroughly mixed using a planetary mill to obtain a negative electrode slurry. The electrode had a density of 1.6 g / cm. 3 A sample for measuring 180-degree peel strength was prepared, and a 180-degree peel test was carried out. The results are shown in Comparative Example 1 in Table 2.

[0145] [Comparative Electrode Preparation Example 2] An electrode was prepared in the same manner as in Electrode Example 1, except that 65.4 parts by mass of graphite and 30 parts by mass of SiO were used as negative electrode active materials, and 1 part by mass of acetylene black, 0.1 part by mass of CNT (manufactured by OCSiAL), 2 parts by mass of carboxymethyl cellulose sodium salt were used as conductive additives, and 5 parts by mass of the solid content of Binder Composition F obtained in Comparative Synthesis Example 2 of the Binder Composition were added. Water was further added so that the solid content concentration of the slurry became 35% by mass, and the mixture was thoroughly mixed using a planetary mill to obtain a negative electrode slurry. The electrode had a density of 1.6 g / cm. 3 A sample for measuring 180-degree peel strength was prepared, and a 180-degree peel test was carried out. The results are shown in Example 2 in Table 2.

[0146]

[0147] <Battery Production Examples> [Coin Battery Production Example 1] In a glove box filled with argon gas, the negative electrode obtained in Electrode Production Example 1, a 18 μm thick polypropylene / polyethylene porous film as a separator, and an electrode (3.0 mAh / cm) using an LCO (LiCoO) active material as a positive electrode were charged. 2A laminate of two laminated electrodes (manufactured by Hohsen Co., Ltd.) was thoroughly impregnated with an electrolyte solution of 1 mol / L lithium hexafluorophosphate in ethylene carbonate and diethyl carbonate (volume ratio 3:7) containing 2 wt% vinylene carbonate and 0.5 wt% fluoroethylene carbonate, and then the laminate was crimped to produce a 2032-type coin battery for testing. The evaluation results of the cycle test are shown in Example 1 of Table 3.

[0148] [Coin Battery Manufacturing Example 2] A coin battery was manufactured in the same manner as in Coin Battery Manufacturing Example 1, except that the negative electrode obtained in Electrode Manufacturing Example 2 was used. The evaluation results of the cycle test measurements are shown in Example 2 in Table 3.

[0149] Coin Battery Manufacturing Example 3 A coin battery was manufactured in the same manner as in Coin Battery Manufacturing Example 1, except that the negative electrode obtained in Electrode Manufacturing Example 3 was used.

[0150] Coin Battery Manufacturing Example 4 A coin battery was manufactured in the same manner as in Coin Battery Manufacturing Example 1, except that the negative electrode obtained in Electrode Manufacturing Example 4 was used.

[0151] [Comparative Coin Battery Production Example 1] A coin battery was produced in the same manner as in Coin Battery Production Example 1, except that the negative electrode obtained in Comparative Electrode Production Example 1 was used. The evaluation results of the cycle test measurements are shown in Comparative Example 1 in Table 3.

[0152] Comparative Coin Battery Production Example 2 A coin battery was produced in the same manner as in Coin Battery Production Example 1, except that the negative electrode obtained in Comparative Electrode Production Example 2 was used.

[0153] Table 3 shows the results of evaluating the battery properties of the coin batteries of Examples and Comparative Examples.

[0154] Compared with Comparative Example 1, Examples 1 and 2 of the present invention showed that by using the binder of the present invention, better binding properties were exhibited in the electrode while maintaining excellent cycle characteristics in the coin battery.

[0155] As described above, the coin batteries prepared in Examples 1 to 4 and Comparative Examples 1 and 2 were subjected to the above-mentioned measurement 2 of charge / discharge efficiency (measurement of 5-cycle charge / discharge capacity retention rate (%)). The evaluation results are shown in Table 4.

[0156]

[0157] It was confirmed that the coin batteries produced in Examples 1 to 4 and Comparative Examples 1 and 2 did not impair battery performance when used in electricity storage devices.

[0158] The electrode binder of the present invention has excellent binding properties, and when used in an electricity storage device, it is useful for in-vehicle applications such as electric vehicles and hybrid electric vehicles, and for electricity storage devices such as storage batteries for home power storage.

Claims

1. An electrode binder comprising a polymer, wherein the polymer comprises a structural unit (A), and the structural unit (A) is a structural unit derived from a triazine thiol having an unsaturated group and / or a structural unit derived from a phosphate ester having an unsaturated group.

2. The electrode binder according to claim 1, wherein the polymer contains a structural unit derived from a (meth)acrylic acid ester.

3. The electrode binder according to claim 2, wherein the polymer contains 40% by mass or more of structural units derived from the (meth)acrylic acid ester.

4. The electrode binder according to claim 2 or 3, wherein the structural unit derived from a (meth)acrylic acid ester comprises at least one structural unit selected from the group consisting of a structural unit (B) derived from a (meth)acrylic acid alkyl ester monomer and a structural unit (C) derived from an acrylic acid ester monomer having an aromatic group.

5. The electrode binder according to any one of claims 1 to 3, wherein in the structural unit (A), the structural unit derived from a phosphate ester having an unsaturated group has a chemical structure represented by the following general formula (A): [In general formula (A), AO is an alkylene oxide group, and n is an integer of 1 to 6.] 6. An electrode comprising the electrode binder according to claim 1 or 2.

7. The electrode according to claim 6, wherein the active material (100% by mass) in the electrode contains 20% by mass or more of a silicon-based compound.

8. An electricity storage device comprising the electrode according to claim 6.

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