Electrode binder, electrode, and electricity storage device

Abstract

To provide a binder for electrodes capable of providing excellent binding properties when used in electrodes and excellent bendability (flexibility), which is excellent charging and discharging efficiency when used in power storage devices.SOLUTION: A binder for electrodes is composed of polymers containing structural units derived from (meth)acrylic acid alkyl ester monomers, and the structural units are derived from ester monomers having an aromatic group, which is composed of a specific molar ratio.SELECTED DRAWING: None

Description

[Technical Field]

[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. [Background technology]

[0002] Energy storage devices such as lithium-ion secondary batteries and electrochemical capacitors are used in electronic devices such as mobile phones, laptops, camcorders, etc. 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 between active materials, between the active material and the conductive additive, and between the active material and the current collector, thereby improving electrical properties (for example, 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 for example, a new binder is proposed in Patent Document 1. However, in recent years, there has been a demand for binders that are particularly excellent in binding properties, and further investigation is required.

[0006] Therefore, Patent Documents 2 and 3 exemplify aromatic monomers as one of the structural units of polymers, but do not provide any specific disclosure regarding the polymers in the examples. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2013 / 180103 [Patent Document 2] JP 2001-35496 A [Patent Document 3] International Publication No. 2017 / 047379 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide an electrode binder that has excellent binding properties when used in electrodes, as well as excellent flexibility, and that has excellent charge / discharge efficiency when used in electricity storage devices. [Means for solving the problem]

[0009] As a result of extensive investigations to achieve the above object, the present inventors have found that by using a polymer comprising a structural unit derived from a (meth)acrylic acid alkyl ester monomer and a structural unit derived from an ester monomer having an aromatic group, in a specific molar ratio, as an electrode binder, the polymer exhibits excellent binding properties and flexibility when used in an electrode, and further exhibits excellent charge / discharge efficiency when used in an electricity storage device, thereby completing the present invention.

[0010] That is, the present invention relates to the following:

[0011] Item 1: A structural unit (A) derived from a (meth)acrylic acid alkyl ester monomer; The following general formula (1) [ka] (In the formula, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, R 2 is an aromatic group which may have a substituent. A polymer containing a structural unit (B) derived from a monomer represented by An electrode binder comprising a polymer in which the molar ratio of the structural unit (A) to the structural unit (B) in the polymer is 0.5 to 2.5. Item 2: The structural unit (B) is represented by the following general formula (2): [ka] (In the formula, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, 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 is an alkylene group having 1 to 3 carbon atoms or a carbonyl group, R 14 represents an aromatic group which may have a substituent, q and r represent integers of 0 to 3, and s represents an integer of 0 to 1. Item 2. The electrode binder according to item 1, wherein the structural unit is derived from a monomer represented by the formula: Item 3 Furthermore, the following general formula (3): [ka] (In the formula, 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, and n is an integer of 2 to 30. Item 3. The electrode binder according to Item 1 or 2, comprising a polymer containing a structural unit (C) derived from a monomer having a hydroxyl group, represented by the following formula: Item 4. The electrode binder according to any one of Items 1 to 3, further comprising a polymer containing a structural unit (D) derived from a polyfunctional (meth)acrylate monomer having five or fewer functionalities. Item 5 In the structural unit (D), the polyfunctional (meth)acrylate monomer having a functionality of 5 or less is represented by the following general formula (5): [ka] (In the formula, R 16 are the same or different and each is a hydrogen atom or a methyl group, and R 17 Item 5. The electrode binder according to item 4, wherein the compound is represented by the formula: wherein R is a pentavalent or less organic group having 2 to 100 carbon atoms, and m is an integer of 5 or less. Item 6. The electrode binder according to any one of Items 1 to 5, wherein the structural unit (A) derived from a (meth)acrylic acid alkyl ester monomer is a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group having 1 to 12 carbon atoms. Item 7. An electrode binder composition comprising the electrode binder according to any one of items 1 to 6. Item 8. An electrode material comprising the electrode binder according to any one of items 1 to 6. Item 9. An electrode material comprising the electrode binder according to any one of items 1 to 6 and an active material. Item 10. The electrode material according to Item 9, wherein activated carbon is used as the active material. Item 11. The electrode material according to Item 9, wherein a silicon-based compound is used as the active material. Item 12. An electrode comprising the electrode material according to any one of items 9 to 11. Item 13. An electricity storage device comprising the electrode according to Item 12. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an electrode binder that has excellent binding properties when used in an electrode and excellent flexibility, and that has excellent charge-discharge efficiency when used in an electricity storage device. Furthermore, according to the present invention, it is possible to provide an electrode binder composition, an electrode material, and an electrode that contain the electrode binder, and an electricity storage device that includes the electrode.

[0013] The electrode binder of the present invention has excellent binding properties, and is particularly useful when activated carbon is used as the active material in the electrode material, because the excellent binding properties are obtained.

[0014] The electrode binder of the present invention exhibits particularly remarkable effects when a silicon-based compound is used as the active material for the negative electrode. Typically, the volume change during charge and discharge is approximately 10% when a carbon material is used, whereas when a silicon-based compound is used, the volume change during charge and discharge is nearly 200%, resulting in a significant capacity loss due to charge and discharge cycles. Even when a silicon-based compound is used as the active material for the negative electrode, the present invention is useful because it exhibits high binding properties, excellent flexibility, high charge and discharge efficiency, and low DC internal resistance without compromising its effectiveness. DETAILED DESCRIPTION OF THE INVENTION

[0015] In this specification, the term "electricity storage device" includes secondary batteries (lithium ion secondary batteries, nickel-metal hydride secondary batteries, etc.) and electrochemical capacitors. In addition, in this specification, "(meth)acrylate" means "acrylate or methacrylate," and the same applies to similar expressions.

[0016] <1. Electrode binder> The electrode binder of the present invention comprises a structural unit (A) derived from a (meth)acrylic acid alkyl ester monomer, The following general formula (1) [ka] (In the formula, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, R 2 is an aromatic group which may have a substituent. A polymer containing a structural unit (B) derived from a monomer represented by The polymer is characterized by including a polymer in which the molar ratio of the structural unit (A) to the structural unit (B) is 0.5 to 2.5.

[0017] The structural units of the polymer of the present invention will be described in detail below.

[0018] The structural unit (A) is a structural unit derived from a (meth)acrylic acid alkyl ester monomer.

[0019] The structural unit (A) is preferably a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group of 1 to 12 carbon atoms, more preferably a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group of 1 to 8 carbon atoms, even more preferably a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group of 1 to 6 carbon atoms, and particularly preferably a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group of 2 to 4 carbon atoms.

[0020] Specific examples of preferred structural units (A) 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. The structural unit (A) may be of one type, or two or more types.

[0021] The proportion of the structural unit (A) in the polymer is not particularly limited, as long as the molar ratio of the structural unit (A) to the structural unit (B) in the polymer is within the range of 0.5 to 2.5. The lower limit of the proportion of the structural unit (A) in the polymer is preferably 30 mol% or more, more preferably 35 mol% or more, and particularly preferably 40 mol% or more. The upper limit of the proportion of the structural unit (A) in the polymer is preferably 75 mol% or less, more preferably 70 mol% or less, and particularly preferably 60 mol% or less. This range is preferred in terms of improving emulsion stability.

[0022] The structural unit (B) is represented by the following general formula (1): [ka] (In the formula, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, R 2 is an aromatic group which may have a substituent. It is a structural unit derived from

[0023] The structural unit (B) is represented by the following general formula (2): [ka] (In the formula, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms, 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 is 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 integers of 0 to 3, and s is an integer of 0 to 1.

[0024] In the structural unit (B), 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. R 2 is an aromatic group which may have a substituent. Examples of the substituent include alkyl groups, alkyl groups such as methyl, ethyl, and isopropyl, unsaturated hydrocarbon groups such as vinyl, halogeno groups such as fluoro, chloro, bromo, and iodo, amino, nitro, and carboxyl groups. The aromatic ring may have two or more rings. 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 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. R 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. R 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, alkyl groups such as methyl, ethyl, and isopropyl, unsaturated hydrocarbon groups such as vinyl, halogeno groups such as fluoro, chloro, bromo, and iodo, amino, nitro, and carboxyl groups. The aromatic ring may have two or more rings. q and r are integers of 0 to 3, preferably integers of 0 to 2, and preferably satisfy q+r≧1. s is an integer of 0 to 1.

[0025] Specific examples of preferred structural units (B) include structural units derived from 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 structural unit (B) may be of one type, or may be of two or more types.

[0026] The ratio of the structural unit (B) in the polymer is not particularly limited, as long as the molar ratio of the structural unit (A) to the structural unit (B) in the polymer is within the range of 0.5 to 2.5. The lower limit of the ratio of the structural unit (B) in the polymer is preferably 20 mol% or more, more preferably 24 mol% or more, and particularly preferably 27 mol% or more. The upper limit of the ratio of the structural unit (B) in the polymer is preferably 60 mol% or less, more preferably 55 mol% or less, and particularly preferably 50 mol% or less. This range is preferred in that it improves the affinity between the current collector foil and the active material when used in an electrode.

[0027] In the polymer, the molar ratio of the structural unit (A) to the structural unit (B) in the polymer (mol of structural unit (A) / mol of structural unit (B)) is preferably 0.5 or more, more preferably 0.75 or more, and particularly preferably 1 or more, and is preferably 2.5 or less, more preferably 2.2 or less, and particularly preferably 2 or less. By setting the ratio within this range, the binder of the present invention will have excellent binding properties when used in electrodes and will also have excellent flexibility, and will have excellent charge and discharge efficiency when used in electricity storage devices.

[0028] The polymer has the following general formula (3): [ka] (In the formula, R 15is a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, x is an integer of 2 to 8, and n is an integer of 2 to 30. It is preferable that the polymer contains a structural unit (C) derived from a monomer having a hydroxyl group, represented by the following formula (I), in that the ionic conductivity is improved when the polymer is used in an electrode.

[0029] In general formula (3), R 15 As the structural unit (C), a monomer having a hydroxyl group such as (R 15 is a hydrogen atom or a methyl group).

[0030] In the general formula (3), (C x H 2x O) 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.

[0031] 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.

[0032] The structural unit (C) is preferably derived from a monomer having a hydroxyl group represented by the following general formula (4). [ka] In general formula (4), R 15is 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 2 to 30. Here, o and p merely represent the constituent ratio of the constituent units, and do not mean only compounds consisting of blocks of (C2H4O) repeating units and blocks of (C3H6O) repeating units, but may also mean compounds in which (C2H4O) repeating units and (C3H6O) repeating units are arranged alternately or randomly, or compounds in which random portions and block portions are mixed.

[0033] In general formula (4), R 15 As the structural unit (C), a monomer having a hydroxyl group such as (R 15 is a hydrogen atom or a methyl group).

[0034] 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.

[0035] Specific examples of the hydroxyl group-containing 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, polypropylene glycol mono(meth)acrylate, polyethylene glycol-propylene glycol-mono(meth)acrylate, polyethylene glycol-tetramethylene glycol-mono(meth)acrylate, etc. 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, and polypropylene glycol mono(meth)acrylate are preferred.

[0036] The structural unit (C) may be of one type, or of two or more types.

[0037] When the polymer contains the structural unit (C), the ratio thereof is not particularly limited, as long as the molar ratio of the structural unit (A) to the structural unit (B) in the polymer is within the range of 0.5 to 2.5. In the polymer, the lower limit of the molar ratio of the structural unit (C) is preferably 0.5 mol% or more, more preferably 1.0 mol% or more, and particularly preferably 2.0 mol% or more. In the polymer, the upper limit of the ratio of the structural unit (C) is preferably 15 mol% or less, more preferably 12 mol% or less, and particularly preferably 10 mol% or less.

[0038] In order to stabilize the binder particles, it is preferable that the polymer contains a structural unit (D) derived from a polyfunctional (meth)acrylate monomer having five or fewer functionalities. The structural unit (D) is preferably a structural unit derived from the following general formula (5): [ka]

[0039] In general formula (5), R 16 are the same or different and each is a hydrogen atom or a methyl group, and R 17 is a pentavalent or less organic group having 2 to 100 carbon atoms, and m is an integer of 5 or less.

[0040] In general formula (5), m is preferably 2 to 5 (i.e., the structural unit (D) is a structural unit derived from a difunctional to pentafunctional (meth)acrylate), more preferably 3 to 5 (i.e., the structural unit (D) is a structural unit derived from a trifunctional to pentafunctional (meth)acrylate), and particularly preferably 3 to 4 (i.e., the structural unit (D) is a structural unit derived from a trifunctional to tetrafunctional (meth)acrylate).

[0041] In the structural unit (D), specific examples of the structural unit derived from a bifunctional (meth)acrylate 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, and bis(meth)acryloyloxyethyl phosphate.

[0042] Specific examples of the structural unit (D) derived from a trifunctional (meth)acrylate include structural units derived from 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, structural units derived from trifunctional (meth)acrylates selected from trimethylolpropane tri(meth)acrylate, trimethylolpropane EO-added tri(meth)acrylate, and pentaerythritol tri(meth)acrylate are preferred.

[0043] In the structural unit (D), specific examples of the structural unit derived from a tetrafunctional (meth)acrylate include structural units derived from tetrafunctional (meth)acrylates such as ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, and pentaerythritol EO-adduct tetra(meth)acrylate.

[0044] In the structural unit (D), a specific example of a structural unit derived from a pentafunctional (meth)acrylate is a structural unit derived from dipentaerythritol penta(meth)acrylate.

[0045] When the polymer contains the structural unit (D), the ratio thereof is not particularly limited, as long as the molar ratio of the structural unit (A) to the structural unit (B) in the polymer is within the range of 0.5 to 2.5. The lower limit of the molar ratio of the structural unit (D) in the polymer is preferably 0.05 mol% or more, more preferably 0.1 mol% or more, and particularly preferably 0.2 mol% or more. The upper limit of the ratio of the structural unit (D) is preferably 10 mol% or less, more preferably 5 mol% or less, and particularly preferably 3 mol% or less.

[0046] The polymer preferably contains a structural unit (E) derived from a (meth)acrylic acid monomer, as this improves the affinity with the active material when used in an electrode.

[0047] Examples of the structural unit (E) include structural units derived from a compound selected from acrylic acid and methacrylic acid. The structural unit (E) contained in the polymer may be one type, or two or more types.

[0048] When the polymer contains the structural unit (E), the proportion thereof is not particularly limited, as long as the molar ratio of the structural unit (A) to the structural unit (B) in the polymer is within the range of 0.5 to 2.5. The lower limit of the proportion of the structural unit (E) in the polymer is preferably 3 mol% or more, more preferably 4 mol% or more, and particularly preferably 5 mol% or more. The upper limit of the proportion of the structural unit (E) is preferably 15 mol% or less, more preferably 13 mol% or less, and particularly preferably 12 mol% or less.

[0049] In addition to the above, the polymer may also have structural units derived from other monomers 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.

[0050] Methods for obtaining polymers include conventional emulsion polymerization and soap-free emulsion polymerization. Specifically, a composition containing monomers, emulsifiers, polymerization initiators, water, and, if necessary, dispersants, chain transfer agents, pH adjusters, 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. Polymerization is then initiated by increasing the temperature while stirring, resulting in a spherical polymer latex in which the polymer is dispersed in water. The monomers can be added during polymerization by batch charging, monomer dripping, pre-emulsion dripping, or other methods, or by combining two or more of these methods. Pre-emulsion dripping refers to an addition method in which the monomers, emulsifiers, water, etc. are first emulsified, and the resulting emulsion is then added dropwise.

[0051] 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.

[0052] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alcohol ethers, polyoxyethylene alkylphenyl 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 Daiichi Kogyo Seiyaku Co., Ltd.), Antox LMA (manufactured by Nippon Nyukazai Co., Ltd.), and Antox EMH (manufactured by Nippon Nyukazai Co., Ltd.).

[0053] 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.

[0054] These nonionic surfactants and / or anionic surfactants may be used alone or in combination of two or more.

[0055] The reactive nature of the reactive surfactant means that it contains 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, it is covalently bonded to and incorporated into part of the polymer. This results in good emulsion polymerization and good dispersion of the produced polymer, and excellent physical properties (flexibility, binding ability) as a binder for electrodes.

[0056] The amount of the constituent units of the emulsifier 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).

[0057] 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.

[0058] 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).

[0059] 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.

[0060] 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 charged monomer (100% by mass).

[0061] A chain transfer agent can be used as needed. 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, 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 monomer.

[0062] In producing the polymer, the polymerization temperature and polymerization time are not particularly limited and can be appropriately selected depending on the type of polymerization initiator used, but generally, the polymerization temperature is 20 to 100°C and the polymerization time is 0.5 to 100 hours.

[0063] 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, per 100 parts by mass of the polymer.

[0064] <2. Binder composition for electrodes> The electrode binder composition of the present invention contains the electrode binder of the present invention described above in the section "1. Electrode Binder" together with a solvent, and the electrode binder may be dispersed in the solvent. The solvent may 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.

[0065] The electrode binder composition of the present invention is preferably an aqueous binder composition in which the electrode binder is dispersed in water.

[0066] The electrode binder composition of the present invention may be an emulsion using an emulsion produced when obtaining a polymer.

[0067] The content of the electrode binder in the electrode binder composition of the present invention is not particularly limited, but the electrode binder is preferably contained so that the solid content concentration of the electrode binder is 0.2 to 80 mass%, more preferably 0.5 to 70 mass%, and particularly preferably 0.5 to 60 mass%. The solid content in the binder composition is usually considered to be the polymer and emulsifier (only when the polymer is used by emulsion polymerization).

[0068] The pH of the electrode binder composition of the present invention can be adjusted by using a base as a pH adjuster as needed. Specific examples of the base 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.

[0069] <3. Electrode material> The electrode material of the present invention contains at least an active material and the electrode binder of the present invention described above in the section "1. Electrode Binder" and may further contain a conductive additive. The electrode material of the present invention can also be produced using the electrode binder composition of the present invention described above in the section "2. Electrode Binder Composition," which contains the electrode binder of the present invention together with a solvent. Specifically, in lithium-ion batteries, 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 electric double layer capacitors (electrochemical capacitors), 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.

[0070] 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.

[0071] A preferred example of the positive electrode active material used in a lithium ion battery is Li x CoO2, Li x NiO2, Li x MnO2, Li x CrO2, Li x FeO2, Li x Co a Mn 1-a O2, Li x Co a Ni 1-a O2, Li x Co a Cr 1-a O2, Li x Co a Fe 1-a O2, Li x Co a Ti 1-a O2, Li x Mn a Ni 1-a O2, Li x Mn a Cr 1-a O2, Li x Mn a Fe 1-a O2, Li x Mn a Ti 1-a O2, Li x Ni a Cr 1-a O2, Li x Ni a Fe 1-a O2, Li x Ni a Ti 1-a O2, Li x Cr a Fe 1-a O2, Li x Cr a Ti 1-a O2, Li x Fe a Ti 1-a O2, Li x Co b Mn c Ni 1-b-c O2, Li x Ni a Co b Al c O2, Lix Cr b Mn c Ni 1-b-c O2, Li x Fe b Mn c Ni 1-b-c O2, Li x You b Mn c Ni 1-b-c O2, Li x Mn2O4, Li x Mn d Co 2-d O4, Li x Mn d Ni 2-d O4, Li x Mn d Cr 2-d O4, Li x Mn d Fe 2-d O4, Li x Mn d You 2-d O4, Li y MnO3, Li y Mn e Co 1-e O3, Li y Mn e Ni 1-e O3, Li y Mn e Fe 1-e O3, Li y Mn e You 1-e O3, Li x CoPO4, Li x MnPO4, Li x NiPO4, Li x FePO4, Li x Co f Mn 1-f PO4, Li x Co f Ni 1-f PO4, Li x Co f Fe 1-f PO4, Li x Mn f Ni 1-f PO4, Li x Mn f Fe1-f PO4, Li x Ni f Feb 1-f PO4, Li y CoSiO4, Li y MnSiO4, Li y NiSiO4, Li y FeSiO4, Li y Co g Mr 1-g SiO4, Li y Co g Ni 1-g SiO4, Li y Co g Feb 1-g SiO4, Li y Mr g Ni 1-g SiO4, Li y Mr g Feb 1-g SiO4, Li y Ni g Feb 1-g SiO4, Li y CoP h Si 1-h O4, Li y MnP h Si 1-h O4, Li y NiP h Si 1-h O4, Li y FeP h Si 1-h O4, Li y Co g Mr 1-g Q h Si 1-h O4, Li y Co g Ni 1-g Q h Si 1-h O4, Li y Co g Feb 1-g Q h Si 1-h O4, Li y Mr g Ni 1-g Q h Si 1-h O4, Li y Mrg Fe 1-g P h Si 1-h O4, Li y Ni g Fe 1-g P h Si 1-h Examples of the lithium-containing composite oxides include O4 (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).

[0072] Among the above-mentioned preferred positive electrode active materials for use in lithium ion batteries, more preferred positive electrode active materials are, specifically, Li x CoO2, Li x NiO2, Li x MnO2, Li x CrO2, Li x Co a Ni 1-a O2, Li x Mn a Ni 1-a O2, Li x Co b Mn c Ni 1-b-c O2, Li x Ni a Co b Al c O2, Li x Mn2O4, Li y MnO3, Li y Mn e Fe 1-e O3, Li y Mn e Ti 1-e O3, Li x CoPO4, Li x MnPO4, Li x NiPO4, Li x FePO4, Li x Mn f Fe 1-fPO4 can be cited. (Here, 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 provided that 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. Note that the values of x and y above increase or decrease by charge and discharge.)

[0073] As the negative electrode active material used in a lithium ion battery, there is a carbon material (natural graphite, artificial graphite, amorphous carbon, etc.) having a structure (porous structure) capable of occluding and releasing lithium ions, or a powder composed of a metal such as lithium, aluminum-based compound, tin-based compound, silicon-based compound, titanium-based compound, etc. capable of occluding 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. Also, it may be used as a mixed active material of a metal and a carbon material. It is desirable to use a negative electrode active material having a porosity of about 70%.

[0074] In the binder of the present invention, when a silicon-based compound is used as the active material particularly used for the negative electrode of a lithium ion battery, a more remarkable effect can be obtained.

[0075] Examples of the silicon-based compound include Si element, an alloy with Si, an oxide containing Si, a carbide containing Si, etc., such as Si, SiB4, SiB6, Mg2Si, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu5Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, SiO x (0 < x ≦ 2), SnSiO x , LiSiO can be exemplified, and SiO x (0 < x ≦ 2) is preferable, and it is silicon monoxide (SiO), etc.

[0076] The content of the silicon-based compound relative to the total amount of active material (100% by mass) is preferably at least 1% by mass, more preferably at least 2% by mass, and particularly preferably at least 4% by mass, and is preferably at most 80% by mass, more preferably at most 60% by mass, and particularly preferably at most 40% by mass.

[0077] In the binder of the present invention, when a silicon-based compound is used as the active material for the negative electrode, it is preferable to use a carbon material in combination as the active material.

[0078] 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, etc., and graphite is preferred.

[0079] The content of the carbon material relative to the total amount of active material (100% by mass) is preferably 20% by mass or more at the lower limit, more preferably 40% by mass or more, and particularly preferably 60% by mass or more at the upper limit, and is preferably 99% by mass or less, more preferably 98% by mass or less, and particularly preferably 96% by mass or less at the upper limit.

[0080] 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.

[0081] Activation can be carried out 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).

[0082] The content of the active material in the electrode material is not particularly limited, and may be, for example, about 99.9 to 50 mass%, more preferably about 99.5 to 70 mass%, and even more preferably about 99 to 85 mass%, relative to the electrode material (100 mass%) excluding components for making a slurry such as water. The active material may be used alone or in combination of two or more types.

[0083] 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, and metal powders. These conductive additives may be used alone or in combination of two or more.

[0084] 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, and 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.

[0085] 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.

[0086] Examples of sodium or ammonium salts of cellulose compounds include sodium or ammonium salts of alkylcelluloses in which cellulose polymers are substituted with various derivative groups. Specific examples include methyl cellulose, methyl ethyl cellulose, ethyl cellulose, and sodium, ammonium, and triethanolammonium salts of carboxymethyl cellulose (CMC). Sodium 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.

[0087] 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.

[0088] 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.

[0089] 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 %.

[0090] When the electrode material of the present invention is used in the form of a slurry, the proportion of the polymer 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%.

[0091] 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. To increase the efficiency of dispersion, the material may be heated within a range that does not affect the material.

[0092] <4. Electrode> The electrode of the present invention is characterized by comprising the electrode material of the present invention described above in the section "3. Electrode material" and a current collector. Details of the electrode material of the present invention are as described above.

[0093] 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.

[0094] The method for producing the electrode is not particularly limited and a common method can be used, such as applying the battery material uniformly to an appropriate thickness onto the surface of a current collector (metal electrode substrate) using a doctor blade method, applicator method, silk screen method, or the like.

[0095] For example, in the doctor blade method, electrode slurry is applied to a metal electrode substrate and then uniformly applied to an appropriate thickness using a blade with a specified 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 then press-molded using a press machine to produce the electrode material. After pressing, the electrode may be heat-treated again to remove water, solvent, emulsifier, etc.

[0096] <5. Energy storage devices> The electricity storage device of the present invention is characterized by comprising the positive electrode, negative electrode, and electrolyte solution described above in the section "4. 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 electrodes of the present invention are as described above. Note that, for the electricity storage device of the present invention, it is sufficient to use an electrode using an electrode material containing the electrode binder of the present invention for at least one of the positive electrode and the negative electrode, and a known electrode can be used for the electrode not using the electrode material containing the electrode binder of the present invention.

[0097] The electrolytic solution is not particularly limited, and a known electrolytic solution can be used. Specific examples of the electrolytic solution include a solution containing an electrolyte and a solvent. The electrolyte and the solvent may each be used alone or in combination of two or more.

[0098] Examples of the electrolyte include lithium salt compounds, such as LiBF, LiPF, LiClO, LiCF, SO, LiN(CF, SO), LiN(C, F, SO), LiN[CF, SC(C, F, SO)], but are not limited to these.

[0099] Examples of electrolytes other than lithium salt compounds include tetraethylammonium tetrafluoroborate, triethylmonomethylammonium tetrafluoroborate, and tetraethylammonium hexafluorophosphate.

[0100] Examples of the solvent used in the electrolytic solution include an organic solvent and a room temperature molten salt.

[0101] Examples of the organic solvent include aprotic organic solvents, and specific examples thereof include linear ethers such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl 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 diethyl ether, and two or more of these may be used in combination.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] Examples of tetraalkylammonium ions include, but are not limited to, trimethylethylammonium ion, trimethylethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, tetrapentylammonium ion, and triethylmethylammonium ion.

[0106] Examples of alkylpyridinium ions include, but are not limited to, N-methylpyridinium ion, N-ethylpyridinium ion, N-propylpyridinium ion, N-butylpyridinium ion, 1-ethyl-2-methylpyridinium ion, 1-butyl-4-methylpyridinium ion, and 1-butyl-2,4-dimethylpyridinium ion.

[0107] Examples of imidazolium ions include, but are not limited to, 1,3-dimethylimidazolium ion, 1-ethyl-3-methylimidazolium ion, 1-methyl-3-ethylimidazolium ion, 1-methyl-3-butylimidazolium ion, 1-butyl-3-methylimidazolium ion, 1,2,3-trimethylimidazolium ion, 1,2-dimethyl-3-ethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, and 1-butyl-2,3-dimethylimidazolium ion.

[0108] The anion species of room temperature molten salts include halide ions such as chloride ions, bromide ions, and iodide ions, as well as 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.

[0109] The room temperature molten salt may be used alone or in combination of two or more.

[0110] 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 ZrO), 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.

[0111] 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 is then 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.

[0112] 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. [Example]

[0113] 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.

[0114] The adhesiveness and flexibility of the produced electrodes were evaluated as follows.

[0115] <Binding test> (Measuring equipment) Peel strength tester: Strograph E3-L (Toyo Seiki Co., Ltd.)

[0116] (Binding test method) The adhesion test was performed using a 180° peel test. Specifically, the electrode was cut into a size of 2 cm wide x 5 cm long, and tape (adhesive tape: Nichiban, 1.8 cm wide x 5 cm long) was attached. One end of the electrode in the longitudinal direction was fixed to Strograph E3-L, and the tape was peeled off in the 180° direction at a test speed of 50 mm / min and a load range of 5 N. The test was performed three times, and the weighted average was calculated. The evaluation results are summarized in Tables 2 and 3.

[0117] (Bending test method) The bending test was performed using a mandrel bending test. Specifically, the electrode was cut into a piece 3 cm wide x 8 cm long, and the electrode was bent 180° at the center of the length (4 cm portion) toward the substrate (with the electrode surface facing outward) using a 4 mm diameter stainless steel rod as support. The condition of the coating film at the bent portion was observed. Five measurements were performed using this method. A rating of ◯ was given if no cracks or peeling occurred on the electrode surface or peeling from the current collector in any of the five measurements. A rating of × was given if cracks or peeling occurred in one or more locations. The evaluation results are summarized in Tables 2 and 3.

[0118] [Characteristics evaluation of fabricated activated carbon batteries] The characteristics of the coin battery using the activated carbon electrode were evaluated by measuring the charge / discharge efficiency. The evaluation results are summarized in Table 2. <Charge / discharge efficiency measurement> (Measuring equipment) Charge / discharge evaluation device: TOSCAT-3100 (Toyo Systems Co., Ltd.) (Measurement method) The coin battery was charged at a constant current of 10 C to 2.7 V, and then charged at a constant voltage of 0.5 C. After charging, the battery was rested for 10 minutes. It was then discharged at a constant current of 10 C to 1.5 V. This cycle constitutes one charge-discharge cycle, and 10 cycles of charge-discharge were performed. After the above procedure, the coin battery was charged at a constant current of 1C up to 2.7V, and then charged at a constant voltage of 0.05C. After charging, the battery was left to rest for 10 minutes. Finally, it was discharged at a constant current of 1C down to 1.5V. The discharge capacity at 1C was divided by the charge capacity to obtain a percentage, which was used to determine the charge / discharge efficiency (%). The evaluation results are summarized in Table 2.

[0119] [Characteristics evaluation of the fabricated battery] The characteristics of the coin batteries using the silicon-based compound-containing electrodes were evaluated by measuring the charge / discharge efficiency. The evaluation results are summarized in Table 3. <Measurement of DC internal resistance> (Measuring equipment) Charge / discharge evaluation device: TOSCAT-3100 (Toyo Systems Co., Ltd.) (Measurement method) The fabricated lithium-ion battery was charged to 3.0 V by constant current / constant voltage discharge. The final current was equivalent to 1 C. After discharge, the battery was allowed to rest for 10 minutes. It was then charged at a constant current of 2 C, and the internal resistance R (Ω) = ΔE / I of the lithium-ion battery at a 100% state of charge (SOC 100%) was measured from the current value I (mA) and the voltage drop ΔE (mV) after 10 seconds. The lithium-ion battery was discharged at a constant current of 2C for 10 seconds, and then allowed to rest for 10 minutes while returning to a 100% SOC state. It was then charged at a constant current of 1C for 15 minutes, adjusted to a 50% SOC state, and allowed to rest for 10 minutes. It was then discharged at a constant current of 2C, and the internal resistance (R (Ω) = ΔE / I) of the lithium-ion battery at a 50% SOC (50% SOC) was measured from the current (I) (mA) and the voltage drop (ΔE) (mV) after 10 seconds. The lithium-ion battery was discharged at a constant current of 2C for 10 seconds, and then allowed to rest for 10 minutes while returning to a 100% SOC state. It was then charged at a constant current of 1C for 15 minutes, adjusted to a 25% SOC state, and allowed to rest for 10 minutes. It was then discharged at a constant current of 2C, and the internal resistance (R) (Ω) = ΔE / I of the lithium-ion battery at a 25% SOC (25% SOC) was measured from the current (I) (mA) and the voltage drop (ΔE) (mV) after 10 seconds. The evaluation results are summarized in Table 3. <Charge / discharge efficiency measurement> (Measuring equipment) Charge / discharge evaluation device: TOSCAT-3100 (Toyo Systems Co., Ltd.) (Measurement method) The prepared coin batteries were discharged at a constant current and constant voltage of 1C until they reached 0V. After discharge, the batteries were left to rest for 10 minutes. They were then charged at a constant current of 1C until they reached 3.0V. The charge capacity at this time was divided by the discharge capacity to obtain a percentage value for evaluation. The evaluation results are summarized in Table 3.

[0120] <Measurement of average particle size> The average particle size of the polymer was measured under the following conditions. (Measuring equipment) Dynamic light scattering particle size distribution analyzer: Zetasizer Nano (Spectris Co., Ltd.) (Measurement conditions) 1. Sample 50 μL of the synthesized emulsion solution. 2. Dilute the sampled emulsion solution by adding 700 μL of ion-exchanged water three times. 3. Withdraw 2100 μL of liquid from the diluted solution. 4. Add 700 μL of ion-exchanged water to the remaining 50 μL of sample, dilute, and measure.

[0121] <Measurement of aggregates> Polymer aggregates were measured as follows. The polymerized emulsion solution was filtered using a 150-mesh stainless steel wire mesh (Kansai Wire Mesh Co., Ltd.), and aggregates adhering to the stirring blade and beaker were scraped off. The collected aggregates were then washed with ion-exchanged water, dried for 24 hours, and their mass was measured. The measured amount of aggregates was divided by the emulsion yield to obtain the amount of aggregates (mass%).

[0122] [Synthesis Example 1] A beaker was charged with 820.98 mmol of n-butyl acrylate, 427.82 mmol of benzyl methacrylate, 38.50 mmol of acrylic acid, 91.70 mmol of methacrylic acid, 42.78 mmol of polyethylene glycol monomethacrylate (NOF Corp.: Blenmer PE-90), 4.28 mmol of trimethylolpropane triacrylate (Shin-Nakamura Chemical Co., Ltd.: A-TMPT), 2.00 g of sodium dodecyl sulfate as an emulsifier, 300 g of ion-exchanged water, and 0.24 g of ammonium persulfate as a polymerization initiator. The mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. A reactor equipped with a stirrer was heated to 55°C under a nitrogen atmosphere, and the emulsion was added over 2 hours. After the addition of the emulsion, the mixture was allowed to polymerize for an additional hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.3 to 7.8 using a 28% aqueous ammonia solution to obtain a binder composition A (polymerization conversion rate 99% or more, solid content concentration 40.3 wt%, aggregate amount: 0.05 mass%) as an emulsion solution. The average particle size of the obtained polymer was 0.118 μm. The molar ratio (mol%) in the polymer is shown in Table 1.

[0123] [Synthesis Example 2] A beaker was charged with 771.43 mmol of n-butyl acrylate, 402.00 mmol of phenoxyethyl methacrylate, 36.18 mmol of acrylic acid, 86.16 mmol of methacrylic acid, 40.20 mmol of polyethylene glycol monomethacrylate (NOF Corp.: Blenmer PE-90), 4.02 mmol of trimethylolpropane triacrylate (Shin-Nakamura Chemical Co., Ltd.: A-TMPT), 2.00 g of sodium dodecyl sulfate as an emulsifier, 300 g of ion-exchanged water, and 0.24 g of ammonium persulfate as a polymerization initiator. The mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. A reactor equipped with a stirrer was heated to 55°C under a nitrogen atmosphere, and the emulsion was added over 2 hours. After the addition of the emulsion, the mixture was allowed to polymerize for an additional hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.5 to 7.7 using a 28% aqueous ammonia solution to obtain an emulsion solution, Binder Composition B (polymerization conversion rate 99% or more, solids concentration 40.2 wt%, aggregate amount: 0.03 mass%). The average particle size of the obtained polymer was 0.250 μm. The molar ratio (mol%) in the polymer is shown in Table 1.

[0124] [Synthesis Example 3] A beaker was charged with 613.47 mmol of n-butyl acrylate, 505.23 mmol of phenoxyethyl methacrylate, 34.10 mmol of acrylic acid, 81.22 mmol of methacrylic acid, 37.89 mmol of polyethylene glycol monomethacrylate (NOF Corp.: Blenmer PE-90), 3.79 mmol of trimethylolpropane triacrylate (Shin-Nakamura Chemical Co., Ltd.: A-TMPT), 2.00 g of sodium dodecyl sulfate as an emulsifier, 300 g of ion-exchanged water, and 0.24 g of ammonium persulfate as a polymerization initiator. The mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. A reactor equipped with a stirrer was heated to 55°C under a nitrogen atmosphere, and the emulsion was added over 2 hours. After the addition of the emulsion, the mixture was allowed to polymerize for an additional hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.5 to 7.7 using a 28% aqueous ammonia solution to obtain an emulsion solution, Binder Composition C (polymerization conversion rate 97% or more, solids concentration 39.1 wt%, aggregate amount: 0.12 mass%). The average particle size of the obtained polymer was 0.134 μm. The molar ratio (mol%) in the polymer is shown in Table 1.

[0125] [Synthesis Example 4] A beaker was charged with 634.14 mmol of 2-ethylhexyl acrylate, 330.45 mmol of phenoxyethyl methacrylate, 29.74 mmol of acrylic acid, 70.83 mmol of methacrylic acid, 33.05 mmol of polyethylene glycol monomethacrylate (NOF Corp.: Blenmer PE-90), 3.30 mmol of trimethylolpropane triacrylate (Shin-Nakamura Chemical Co., Ltd.: A-TMPT), 2.00 g of sodium dodecyl sulfate as an emulsifier, 300 g of ion-exchanged water, and 0.24 g of ammonium persulfate as a polymerization initiator. The mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. A reactor equipped with a stirrer was heated to 55°C under a nitrogen atmosphere, and the emulsion was added over 2 hours. After the addition of the emulsion, the mixture was allowed to polymerize for an additional hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.4 to 7.8 using a 28% aqueous ammonia solution to obtain an emulsion solution, Binder Composition D (polymerization conversion rate 99% or more, solid concentration 39.7 wt%, aggregate amount: 0.03 mass%). The average particle size of the obtained polymer was 0.109 μm. The molar ratio (mol%) in the polymer is shown in Table 1.

[0126] [Synthesis Example 5] A beaker was charged with 788.99 mmol of n-butyl acrylate, 419.90 mmol of benzyl methacrylate, 38.21 mmol of acrylic acid, 89.58 mmol of methacrylic acid, 41.99 mmol of polyethylene glycol monomethacrylate (NOF Corp.: Blenmer PE-90), 21.00 mmol of trimethylolpropane trimethacrylate (Kyoeisha Chemical Co., Ltd.: Light Ester-TMP), 2.00 g of sodium lauryl sulfate as an emulsifier, 180 g of ion-exchanged water, and 0.36 g of ammonium persulfate as a polymerization initiator. The mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. A reactor equipped with a stirrer was heated to 55°C under a nitrogen atmosphere, and the emulsion was added over 2 hours. After the addition of the emulsion, the mixture was allowed to polymerize for an additional hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.3 to 7.8 using a 28% aqueous ammonia solution to obtain a binder composition E (polymerization conversion rate 97% or more, solids concentration 39.0 wt%, aggregate amount: 0.08 mass%) as an emulsion solution. The average particle size of the obtained polymer was 0.246 μm. The molar ratio (mol%) in the polymer is shown in Table 1.

[0127] [Comparative Synthesis Example 1] A beaker was charged with 936.10 mmol of n-butyl acrylate, 295.30 mmol of phenoxyethyl methacrylate, 37.97 mmol of acrylic acid, 90.42 mmol of methacrylic acid, 42.19 mmol of polyethylene glycol monomethacrylate (NOF Corp.: Blenmer PE-90), 4.22 mmol of trimethylolpropane triacrylate (Shin-Nakamura Chemical Co., Ltd.: A-TMPT), 2.00 g of sodium dodecyl sulfate as an emulsifier, 300 g of ion-exchanged water, and 0.24 g of ammonium persulfate as a polymerization initiator. The mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. A reactor equipped with a stirrer was heated to 55°C under a nitrogen atmosphere, and the emulsion was added over 2 hours. After the addition of the emulsion, the mixture was allowed to polymerize for an additional hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.4 to 7.8 using a 28% aqueous ammonia solution to prepare an emulsion solution, Binder Composition F, but the polymer separated from the water and no emulsion was obtained.

[0128] [Comparative Synthesis Example 2] A beaker was charged with 901.85 mmol of phenoxyethyl methacrylate, 27.81 mmol of acrylic acid, 66.22 mmol of methacrylic acid, 30.90 mmol of polyethylene glycol monomethacrylate (NOF Corp.: Blenmer PE-90), 3.09 mmol of trimethylolpropane triacrylate (Shin-Nakamura Chemical Co., Ltd.: A-TMPT), 2.00 g of sodium dodecyl sulfate as an emulsifier, 300 g of ion-exchanged water, and 0.24 g of ammonium persulfate as a polymerization initiator, and the mixture was thoroughly stirred using an ultrasonic homogenizer to form an emulsion. A reaction vessel equipped with a stirrer was heated to 55°C under a nitrogen atmosphere, and the emulsion was added over 2 hours. After the addition of the emulsion, the mixture was polymerized for an additional hour and then cooled. After cooling, the pH of the polymerization solution was adjusted from 2.5 to 7.8 using a 28% aqueous ammonia solution to obtain an emulsion solution, Binder Composition G (polymerization conversion rate 94% or more, solids concentration 37.9 wt%, aggregate amount: 0.56 mass%). The average particle size of the obtained polymer was 0.130 μm. The molar ratio (mol%) in the polymer is shown in Table 1.

[0129] [Table 1]

[0130] <Example of preparing an electrode containing activated carbon> [Electrode Preparation Example 1] 89 parts by mass of activated carbon was added as an active material, 5 parts by mass of acetylene black as a conductive additive, 2 parts by mass of sodium salt of carboxymethyl cellulose, and 4 parts by mass of the solid content of binder composition A obtained in Example 1 of binder composition synthesis were added, and water was further added so that the solid content concentration of the slurry became 24% by mass. The mixture was thoroughly mixed using a planetary mill to obtain a slurry.

[0131] The resulting slurry was applied to a 20 μm-thick aluminum current collector using a Baker-type applicator with a 100 μm gap, pressed with a roll press, and dried at 150°C in a vacuum for 12 hours or more to produce an 89 μm-thick electrode. The evaluation results of the adhesion test and flex test are shown in Example 1 of Table 2.

[0132] [Electrode Preparation Example 2] An electrode was prepared in the same manner as in Example 1 except that 89 parts by mass of activated carbon was used as the active material, 5 parts by mass of acetylene black as a conductive additive, 2 parts by mass of sodium salt of carboxymethyl cellulose, and 4 parts by mass of the solids content of binder composition B obtained in Example Synthesis 2 of the binder composition were added, and water was added so that the solids concentration of the slurry became 24% by mass. The mixture was thoroughly mixed using a planetary mill to obtain a slurry. The thickness of the obtained electrode was 85 μm. The evaluation results of the adhesion test and flex test are shown in Table 2 for Example 2.

[0133] [Electrode Preparation Example 3] An electrode was prepared in the same manner as in Example 1 except that 89 parts by mass of activated carbon was used as the active material, 5 parts by mass of acetylene black as a conductive additive, 2 parts by mass of sodium salt of carboxymethyl cellulose, and 4 parts by mass of the solids content of binder composition C obtained in Example Synthesis 3 of the binder composition were added, and water was added so that the solids concentration of the slurry became 22% by mass. The mixture was thoroughly mixed using a planetary mill to obtain a slurry. The thickness of the obtained electrode was 96 μm. The evaluation results of the adhesion test and flex test are shown in Table 2 for Example 3.

[0134] [Electrode Preparation Example 4] An electrode was prepared in the same manner as in Example 1 except that 89 parts by mass of activated carbon was used as the active material, 5 parts by mass of acetylene black as a conductive additive, 2 parts by mass of sodium salt of carboxymethyl cellulose, and 4 parts by mass of the solids content of binder composition D obtained in Example Synthesis 4 of the binder composition were added, and water was added so that the solids concentration of the slurry became 22% by mass. The mixture was thoroughly mixed using a planetary mill to obtain a slurry. The thickness of the obtained electrode was 88 μm. The evaluation results of the adhesion test and flex test are shown in Table 2 for Example 4.

[0135] [Comparative electrode preparation example 2] An electrode was prepared in the same manner as in Example 1 except that 89 parts by mass of activated carbon was used as the active material, 5 parts by mass of acetylene black and 2 parts by mass of sodium salt of carboxymethyl cellulose were used as conductive additives, and 4 parts by mass of the solids content of binder composition G obtained in Comparative Synthesis Example 2 of the binder composition was added. Water was then added so that the solids concentration of the slurry became 24% by mass, and the mixture was thoroughly mixed using a planetary mill to obtain a slurry. The thickness of the obtained electrode was 97 μm. The evaluation results of the adhesion test and flex test are shown in Comparative Example 2 in Table 2.

[0136] <Example of manufacturing an electrode containing a silicon compound> [Electrode Production Example 5-1] 92 parts by mass of graphite and 5 parts by mass of SiO were added as active materials, 0.5 parts by mass of acetylene black and 1.8 parts by mass of sodium salt of carboxymethyl cellulose were added as conductive additives, and 0.7 parts by mass of the solid content of binder composition E obtained in Example 5 of binder composition synthesis was added. Water was further added so that the solid content concentration of the slurry became 50.5% by mass, and the mixture was thoroughly mixed using a planetary mixer to obtain a slurry.

[0137] The resulting slurry was applied to a 20 μm-thick aluminum current collector using a Baker-type applicator with a 100 μm gap, pressed with a roll press, and dried at 110°C in a vacuum for 12 hours or more to prepare a 37 μm-thick electrode. The evaluation results of the adhesion test and flex test are shown in Table 3, Example 5-1.

[0138] [Electrode Production Example 5-2] An electrode was prepared in the same manner as in Example 5-1, except that 87 parts by weight of graphite and 10 parts by weight of SiO were used as active materials, 0.5 parts by weight of acetylene black and 1.8 parts by weight of sodium salt of carboxymethyl cellulose were used as conductive additives, and 0.7 parts by weight of the solid content of binder composition E obtained in Example Synthesis 5 of the binder composition was added. Water was then added to the mixture so that the solid content concentration of the slurry became 50.5% by weight, and the mixture was thoroughly mixed using a planetary mixer to obtain a slurry. The thickness of the resulting electrode was 38 μm. The evaluation results of the adhesion test and flex test are shown in Table 3 for Example 5-2.

[0139] [Comparative electrode preparation example 3] An electrode was prepared in the same manner as in Example 5-1, except that 92 parts by weight of graphite and 5 parts by weight of SiO were used as active materials, 0.5 parts by weight of acetylene black and 1.8 parts by weight of sodium salt of carboxymethyl cellulose were used as conductive additives, and 0.7 parts by weight of the solid content of Binder Composition G obtained in Comparative Synthesis Example 2 of the Binder Composition was added. Water was then added to the mixture so that the solid content concentration of the slurry was 50.5% by weight, and the mixture was thoroughly mixed using a planetary mixer to obtain a slurry. The thickness of the resulting electrode was 36 μm. The evaluation results of the adhesion test and flex test are shown in Table 3, Comparative Example 3.

[0140] [Comparative electrode preparation example 4] An electrode was prepared in the same manner as in Example 5-1, except that 87 parts by weight of graphite and 10 parts by weight of SiO were used as active materials, 0.5 parts by weight of acetylene black and 1.8 parts by weight of sodium salt of carboxymethyl cellulose were used as conductive additives, and 0.7 parts by weight of the solid content of Binder Composition G obtained in Comparative Synthesis Example 2 of the Binder Composition was added. Water was then added to the mixture so that the solid content concentration of the slurry became 50.5% by weight, and the mixture was thoroughly mixed using a planetary mixer to obtain a slurry. The thickness of the resulting electrode was 35 μm. The evaluation results of the adhesion test and flex test are shown in Comparative Example 4 in Table 3.

[0141] <Example of manufacturing a battery (electrochemical capacitor) using activated carbon-containing electrodes> [Coin battery (electrochemical capacitor) manufacturing example 1] In a glove box purged with argon gas, the electrode obtained in Example 1 was used as the positive electrode, a 100 μm thick cellulose porous membrane was used as the separator, and the electrode obtained in Example 1 was used as the negative electrode. The electrodes were thoroughly impregnated with a 1.4 mol / L tetraethylmethylammonium-tetrafluoroborate / propylene carbonate solution (manufactured by Kishida Chemical Co., Ltd.) as the electrolyte, and the batteries were crimped to produce a 2032-type coin battery for testing. The evaluation results of the charge / discharge efficiency are shown in Example 1 in Table 2.

[0142] [Coin battery (electrochemical capacitor) manufacturing example 2] A coin battery was fabricated in the same manner as in Coin Battery Example 1, except that the positive and negative electrodes obtained in Electrode Example 2 were used. The evaluation results of charge / discharge efficiency are shown in Example 2 in Table 2.

[0143] [Coin battery (electrochemical capacitor) manufacturing example 3] A coin battery was fabricated in the same manner as in Coin Battery Example 1, except that the positive and negative electrodes obtained in Electrode Example 3 were used. The evaluation results of charge / discharge efficiency are shown in Example 3 of Table 2.

[0144] [Coin battery (electrochemical capacitor) manufacturing example 4] A coin battery was fabricated in the same manner as in Coin Battery Example 1, except that the positive and negative electrodes obtained in Electrode Example 4 were used. The evaluation results of charge / discharge efficiency are shown in Example 4 in Table 2.

[0145] [Comparative manufacturing example 2 of coin battery (electrochemical capacitor)] A coin battery was fabricated in the same manner as in Coin Battery Example 1, except that the positive and negative electrodes obtained in Comparative Electrode Fabrication Example 2 were used. The evaluation results of charge / discharge efficiency are shown in Comparative Example 2 in Table 2.

[0146] <Example of manufacturing a battery (lithium ion battery) using an electrode containing a silicon compound> [Coin battery (lithium ion battery) manufacturing example 5-1] In a glove box purged with argon gas, metallic lithium was used as the positive electrode, an 18 μm polypropylene / polyethylene / polypropylene porous membrane was used as the separator, and the electrode obtained in Example 5-1 was used as the negative electrode. The battery was thoroughly impregnated with 1 mol / L of lithium hexafluorophosphate in ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate (volume ratio 3:5:2, manufactured by Kishida Chemical Co., Ltd.) as the electrolyte, and then crimped to produce a 2032-type test coin battery. The evaluation results for DC internal resistance and charge / discharge efficiency are shown in Table 3 for Example 5-1.

[0147] [Coin battery (lithium ion battery) manufacturing example 5-2] A coin battery was fabricated in the same manner as in Example 5-1 of Coin Battery Fabrication, except that the negative electrode obtained in Example 5-2 of Electrode Fabrication was used. The evaluation results of DC internal resistance and charge / discharge efficiency are shown in Table 3 for Example 5-2.

[0148] [Comparative manufacturing example 3 of coin battery (lithium ion battery)] A coin battery was fabricated in the same manner as in Coin Battery Example 5-1, except for using the negative electrode obtained in Comparative Electrode Fabrication Example 3. The evaluation results of DC internal resistance and charge / discharge efficiency are shown in Comparative Example 3 in Table 3.

[0149] [Comparative manufacturing example 4 of coin battery (lithium ion battery)] A coin battery was fabricated in the same manner as in Example 5-1 of Coin Battery Fabrication, except for using the negative electrode obtained in Comparative Electrode Fabrication Example 4. The evaluation results of DC internal resistance and charge / discharge efficiency are shown in Comparative Example 4 in Table 3.

[0150] Table 2 shows the results of evaluating the physical properties of the activated carbon-containing electrodes of the examples and comparative examples, and the evaluation of the characteristics of the batteries (electrochemical capacitors). [Table 2]

[0151] Table 3 shows the results of evaluating the physical properties of the silicon compound-containing electrodes of the examples and comparative examples, and the evaluation of the characteristics of the lithium ion batteries. [Table 3] [Industrial Applicability]

[0152] The electrode binder of the present invention has excellent binding properties for activated carbon active materials and excellent flexibility when used in electrodes. It also has excellent binding properties for silicon-based compounds and excellent flexibility when used in electricity storage devices. When used in electricity storage devices, the binder has excellent charge / discharge efficiency, making it 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. A structural unit (A) derived from a (meth)acrylic acid alkyl ester monomer, The following general formula (1) 【Chemistry 1】 (In the formula, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms; R 2 represents an aromatic group which may have a substituent. A polymer containing a structural unit (B) derived from a monomer represented by The polymer includes a polymer in which the molar ratio of the structural unit (A) to the structural unit (B) in the polymer is 0.5 to 2.5, The polymer further includes a polymer containing a structural unit (D) derived from a polyfunctional (meth)acrylate monomer having a functionality of 5 or less, Electrode binder for negative electrodes.

2. The structural unit (B) is represented by the following general formula (2): 【Chemistry 2】 (In the formula, R 1 is hydrogen or an alkyl group having 1 to 4 carbon atoms; 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 represents an aromatic group which may have a substituent, q and r represent integers of 0 to 3, and s represents an integer of 0 to 1.

2. The electrode binder according to claim 1, wherein the structural unit is derived from a monomer represented by the formula:

3. Furthermore, the following general formula (3): 【Transformation 3】 (In the formula, 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, and n is an integer of 2 to 30.

3. The electrode binder according to claim 1, comprising a polymer containing a structural unit (C) derived from a monomer having a hydroxyl group represented by the formula:

4. In the structural unit (D), the polyfunctional (meth)acrylate monomer having a functionality of five or less is represented by the following general formula (5): 【Chemistry 4】 (In the formula, R 16 are the same or different and each represents a hydrogen atom or a methyl group, and R 17 is a pentavalent or less organic group having 2 to 100 carbon atoms, and m is an integer of 5 or less.

5. The electrode binder according to any one of claims 1 to 4, wherein the structural unit (A) derived from a (meth)acrylic acid alkyl ester monomer is a structural unit derived from a (meth)acrylic acid alkyl ester monomer having an alkyl group having 1 to 12 carbon atoms.

6. An electrode binder composition comprising the electrode binder according to any one of claims 1 to 5.

7. An electrode material comprising the electrode binder according to any one of claims 1 to 5.

8. An electrode material comprising the electrode binder according to any one of claims 1 to 5 and an active material.

9. 9. The electrode material according to claim 8, wherein activated carbon is used as the active material.

10. 9. The electrode material according to claim 8, wherein the active material is a silicon-based compound.

11. An electrode comprising the electrode material according to any one of claims 8 to 10.

12. An electricity storage device comprising the electrode according to claim 11.

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