Primers for energy storage device electrodes, compositions for forming primer layers, electrodes for energy storage devices, and secondary batteries

Abstract

The present invention provides: a secondary battery which has excellent charge and discharge cycle characteristics (capacity retention) and discharge rate characteristics (discharge capacity ratio); and a primer for power storage device electrodes, a composition for forming a primer layer, and an electrode for power storage devices, each of which is used for the purpose of obtaining the above-described secondary battery.　A primer for power storage device electrodes, the primer being used for the purpose of forming a primer layer that is arranged between a collector and an electrode active material layer. This primer for power storage device electrodes contains a fluorine-containing copolymer which has a unit based on tetrafluoroethylene or chlorotrifluoroethylene and a unit based on ethylene, hexafluoropropylene or perfluoro(alkyl vinyl ether), but does not substantially have a unit based on vinylidene fluoride, while having an adhesive functional group that is reactive with a hydroxyl group or is capable of forming a hydrogen bond.

Description

[Technical Field]

[0001] The present invention relates to a primer for energy storage device electrodes, a composition for forming a primer layer, an electrode for an energy storage device, and a secondary battery. [Background technology]

[0002] Energy storage devices such as secondary batteries are typically composed of electrodes, non-aqueous electrolytes, separators, and the like as their main components. Electrodes for energy storage devices are generally manufactured by applying an electrode mixture containing electrode active material, conductive material, binder, and liquid medium to the surface of a current collector and then drying it. It is known that fluorine-containing polymers and hydrocarbon polymers are used as binders for electrode mixtures for energy storage devices.

[0003] However, electrode mixtures containing fluorine-containing polymers or hydrocarbon polymers tend to have insufficient adhesion to the current collector surface. Therefore, secondary batteries using electrodes manufactured with binders containing fluorine-containing polymers or hydrocarbon polymers cannot obtain sufficient charge-discharge cycle characteristics (capacity retention rate) or discharge rate characteristics (discharge capacity ratio).

[0004] Therefore, Patent Document 1 proposes that the adhesion of the electrode mixture for energy storage devices to the surface of the current collector is improved by first forming an undercoat layer on the current collector and then applying the electrode mixture for energy storage devices. Patent Document 1 discloses polyurethane resin and epoxy resin as undercoat layers. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-149810 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, as described in Patent Document 3, when polyurethane resin or epoxy resin is used as an undercoat layer, the undercoat layer deteriorates with the charging and discharging of the secondary battery, making it impossible to maintain adhesion of the electrode mixture for the energy storage device to the current collector surface. As a result, sufficient charge-discharge cycle characteristics (capacity retention rate) and discharge rate characteristics (discharge capacity ratio) could not be obtained.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a secondary battery having excellent charge-discharge cycle characteristics (capacity retention rate) and discharge rate characteristics (discharge capacity ratio), as well as a primer for an electrode of an energy storage device for obtaining this secondary battery, a composition for forming a primer layer, and an electrode for an energy storage device. [Means for solving the problem]

[0008] To achieve the above objectives, the present invention employs the following configuration. [1] A primer for an electrode of an energy storage device, for forming a primer layer provided between a current collector and an electrode active material layer, A primer for an energy storage device electrode, comprising a fluorine-containing copolymer having units based on tetrafluoroethylene or chlorotrifluoroethylene, and units based on ethylene, hexafluoropropylene, or perfluoro(alkyl vinyl ether), substantially free of units based on vinylidene fluoride, and having adhesive functional groups that can react with hydroxyl groups or form hydrogen bonds. [2] The primer according to [1], wherein the fluorine-containing copolymer has a melting point of 150°C or higher. [3] The primer according to [1] or [2], wherein the fluorine-containing copolymer has one or more selected from the group consisting of carbonyl-containing groups and hydroxyl groups as the adhesive functional group. [4] The primer according to [3], wherein the fluorine-containing copolymer has at least one carbonyl-containing group selected from the group consisting of a group having a carbonyl group between carbon atoms of a hydrocarbon group, a carbonate group, a carboxyl group, a haloformyl group, an alkoxycarbonyl group, and an acid anhydride group as the adhesive functional group.

[0009] [5] The primer according to any one of [1] to [4], wherein the fluorine-containing copolymer contains units based on tetrafluoroethylene. [6] The primer according to any one of [1] to [5], wherein the fluorine-containing copolymer contains units based on ethylene. [7] The primer according to any one of [1] to [6], wherein the fluorine-containing copolymer contains units based on tetrafluoroethylene and units based on ethylene. [8] Further, the primer according to any one of [1] to [7], which contains a conductive material.

[0010] [9] A composition for forming a primer layer, comprising the primer for a power storage device electrode according to any one of [1] to [8] and a liquid medium.

[10] The composition according to [9], wherein the liquid medium is at least one selected from the group consisting of an aqueous medium, aliphatics, aromatic hydrocarbons, alcohols, ethers, esters, ketones, nitrogen-containing compounds, sulfur-containing compounds, and fluorine-containing compounds.

[11] The composition according to [9], wherein the liquid medium is at least one selected from the group consisting of an aqueous medium, N-methylpyrrolidone, N,N-dimethylacetamide, and an aliphatic hydrocarbon compound having 6 to 10 carbon atoms and one carbonyl group.

[0011]

[12] An electrode for a power storage device, having a current collector and an electrode active material layer formed on the current collector, wherein a primer layer containing the primer for a power storage device electrode according to any one of [1] to [8] is provided between the current collector and the electrode active material layer.

[13] An electrode for a power storage device, having a current collector and an electrode active material layer formed on the current collector, wherein a primer layer formed from the composition for forming a primer layer according to any one of [9] to

[11] is provided between the current collector and the electrode active material layer.

[14] An electrode for a power storage device having a current collector and an electrode active material layer formed on the current collector, wherein a primer layer formed from the powder of the primer for an electrode of a power storage device according to any one of [1] to [8] is provided between the current collector and the electrode active material layer.

[15] A secondary battery including the electrode for a power storage device according to any one of

[12] to

[14] and an electrolyte.

Advantages of the Invention

[0012] According to the primer for an electrode of a power storage device, the composition for forming a primer layer, the electrode for a power storage device, and the secondary battery of the present invention, excellent charge-discharge cycle characteristics (capacity retention rate) and discharge rate characteristics (discharge capacity ratio) can be obtained.

Modes for Carrying Out the Invention

[0013] The definitions of the following terms in this specification and the claims are as follows. A "unit based on a monomer" is a general term for an atomic group directly formed by the polymerization of one molecule of a monomer and an atomic group obtained by chemically converting a part of the atomic group. In this specification, a unit based on a monomer is also simply referred to as a monomer unit. "Monomer" means a compound having a polymerizable carbon-carbon double bond. "Melting point" means the temperature corresponding to the maximum value of the melting peak measured by the differential scanning calorimetry (DSC) method. "Carbonyl-containing group" means a group having a carbonyl group (-C(=O)-) in its structure. "Anhydride group" means a group represented by -C(=O)-O-C(=O)-. The "average particle diameter" of a polymer is a value calculated by cumulant method analysis from the autocorrelation function obtained by the dynamic light scattering method for a sample in which the polymer is diluted with water to a solid content concentration of 1% by mass. [MFR (Melt Flow Rate)] is the mass (g) of copolymer that flows out of a 2mm diameter, 8mm long orifice in 10 minutes, measured using a melt indexer (manufactured by Technoseven Co., Ltd.) in accordance with ASTM D3159, at temperatures of 220°C, 297°C, or 380°C, and under a load of 49N. The value is then converted to the mass of copolymer that flows out per 10 minutes (g / 10 min). The measurement temperature is selected based on the melting point, choosing a temperature 30 to 80°C higher than the melting point. For example, if the melting point is 300°C, the measurement is taken at 380°C; if the melting point is 255°C, it is taken at 297°C; and if the melting point is 183°C, it is taken at 220°C. The "main chain" of a polymer refers to the polymer chain formed by the linkage of two or more monomers. In this specification, the compound represented by Formula 1 will also be referred to as "Compound 1".

[0014] <Primer for electrodes in energy storage devices> The primer for energy storage device electrodes of the present invention (hereinafter also simply referred to as "primer") contains a specific fluorine-containing copolymer (hereinafter also referred to as "copolymer A"). In addition, the primer of the present invention may contain polymers other than copolymer A, additives, etc., as necessary, to the extent that it does not impair the effects of the present invention.

[0015] [Copolymer A] Copolymer A has units based on tetrafluoroethylene (hereinafter also referred to as "TFE") or chlorotrifluoroethylene (hereinafter also referred to as "CTFE") (hereinafter also referred to as "unit a"), and units based on ethylene (hereinafter also referred to as "E"), hexafluoropropylene (hereinafter also referred to as "HFP"), or perfluoroalkyl vinyl ether (hereinafter also referred to as "PAVE") (hereinafter also referred to as "unit b"), substantially lacks units based on vinylidene fluoride (hereinafter also referred to as "VdF") (hereinafter also referred to as "VdF units"), and has adhesive functional groups that can react with hydroxyl groups or form hydrogen bonds. "Substantially lacking VdF units" means either having no VdF units, or having VdF units to an extent that does not affect the chemical resistance of the copolymer. "To an extent that does not affect the chemical resistance of the copolymer" means, for example, that the VdF units are 1 mol% or less relative to the units based on the total monomers of copolymer A. If units based on VdF are present, it is preferable that the VdF units are 0.5 mol% or less relative to the units based on the total monomers of copolymer A. Copolymer A may have units based on monomers other than those mentioned above (excluding VdF), as long as the effects of the present invention are not impaired.

[0016] Copolymer A has units based on TFE (hereinafter also referred to as "TFE units") or units based on CTFE (hereinafter also referred to as "CTFE units") as unit a, and may have both TFE units and CTFE units. Due to its good chemical resistance and oxidation resistance, copolymer A preferably has at least TFE units as unit a, and more preferably has only TFE units.

[0017] Copolymer A has units b that are based on ethylene (hereinafter also referred to as "E units"), HFP (hereinafter also referred to as "HFP units"), or PAVE (hereinafter also referred to as "PAVE units"), and may have two or three of these units. To ensure good adhesion between the current collector and the electrode active material layer, copolymer A preferably has at least E units as unit b, and more preferably has only E units.

[0018] PAVE is preferably compound 1 represented by formula 1 below. Two or more compounds can be used as compound 1. CF2 = CFOR f1 ...Formula 1 [In Equation 1, R f1 This refers to a perfluoroalkyl group having 1 to 10 carbon atoms, or a perfluoroalkyl group having 2 to 10 carbon atoms with oxygen atoms between the carbon atoms. In Equation 1, Rf1 As it has excellent chemical resistance, a perfluoroalkyl group having 1 to 6 carbon atoms is preferred, and a perfluoroalkyl group having 1 to 3 carbon atoms is more preferred.

[0019] As monomers other than the above, in addition to the monomers having an adhesive functional group described below, CH2=CY(CF2) n Compounds represented by Z (where Y and Z are each independently a fluorine atom or a hydrogen atom, and n is 2 to 10) (hereinafter also referred to as "FAE"), etc., fluorine-containing vinyl monomers other than the above, olefinic vinyl monomers other than ethylene such as propylene, vinyl ethers other than PAVE, vinyl esters, and halogen-containing vinyl monomers having a halogen atom other than a fluorine atom can be mentioned. Two or more kinds of monomers other than the above can be used.

[0020] In the above FAE, n in the formula is 2 to 10, preferably 2 to 8, more preferably 2 to 6, and particularly preferably 2, 4, 6. When n is 2 or more, cracks are less likely to occur in the primer layer, and the adhesion between the current collector and the electrode active material layer is easily maintained. When n is 10 or less, it has excellent chemical resistance. Two or more kinds of FAE can be used. Preferred specific examples of such FAE include CH2=CH(CF2)2F, CH2=CH(CF2)4F, CH2=CH(CF2)6F, CH2=CF(CF2)3H, etc. As FAE, CH2=CH-R f2 (R f2 is a perfluoroalkyl group having 2 to 6 carbon atoms, the same hereinafter) is most preferred.

[0021] The copolymer A preferably has a TFE unit as unit a and an E unit as unit b. As the copolymer A having a TFE unit and an E unit, an E / TFE copolymer, an E / TFE / HFP copolymer, an E / TFE / CH2=CH-R f2 copolymer, an E / TFE / CF2=CFOR f1 and an E / TFE / HFP / CH2=CH-R f2Copolymers are preferred. In particular, E / TFE copolymers and E / TFE / CH2=CH-R f2 Copolymers, E / TFE / HFP copolymers are preferred, and E / TFE copolymers and E / TFE / CH2=CH-R copolymers are preferred. f2 Copolymers are particularly preferred. Note that an E / TFE copolymer refers to a copolymer containing both E units and TFE units. The same applies to other copolymers.

[0022] When copolymer A has TFE units as unit a and E units as unit b, the preferred ratio of each unit is as follows. The proportion of TFE units is preferably 25 to 80 mol%, more preferably 40 to 65 mol%, and even more preferably 45 to 63 mol%, relative to the total amount of E units and TFE units. If the proportion of TFE units is 25 mol% or more, the chemical resistance is excellent. If the proportion of E units is 20 mol% or more, the adhesion between the current collector and the electrode active material layer is good.

[0023] When copolymer A has TFE units and E-based units, and further has units based on monomers other than monomers having adhesive functional groups, the proportion of units based on monomers other than monomers having adhesive functional groups is preferably 0.1 to 10.0 mol%, more preferably 0.2 to 8.0 mol%, even more preferably 0.3 to 6.0 mol%, and particularly preferably 0.4 to 4.0 mol%, relative to the total amount of E units and TFE units.

[0024] In copolymer A, adhesive functional groups are preferably selected from the group consisting of carbonyl-containing groups, hydroxyl groups, epoxy groups, amide groups, amino groups, and isocyanate groups. There may be two or more adhesive functional groups in copolymer A.

[0025] As adhesive functional groups in copolymer A, carbonyl-containing groups and hydroxyl groups are preferred from the viewpoint of adhesion to the current collector and electrode active material layer. Among these, carbonyl-containing groups are preferred. Examples of carbonyl-containing groups include groups having a carbonyl group between the carbon atoms of a hydrocarbon group, carbonate groups, carboxyl groups, haloformyl groups, alkoxycarbonyl groups, and acid anhydride groups. Among these, acid anhydride groups and carboxyl groups are preferred, with acid anhydride groups being particularly preferred.

[0026] Examples of hydrocarbon groups having carbonyl groups between carbon atoms include alkylene groups with 2 to 8 carbon atoms. The number of carbon atoms in the alkylene group is the number of carbon atoms that does not include the carbon atoms of the carbonyl group. The alkylene group may be linear or branched.

[0027] A haloformyl group is represented as -C(=O)-X (where X is a halogen atom). Examples of halogen atoms in a haloformyl group include fluorine atoms and chlorine atoms, with fluorine atoms being preferred. The alkoxy group in the alkoxycarbonyl group may be linear or branched, and is preferably an alkoxy group having 1 to 8 carbon atoms, with methoxy and ethoxy groups being more preferred.

[0028] The content of adhesive functional groups in copolymer A is equal to the carbon number of carbon atoms in the main chain of copolymer A (1 × 10⁶). 6 The amount of adhesive functional groups per unit is preferably 10 to 60,000, more preferably 100 to 50,000, even more preferably 100 to 10,000, and particularly preferably 300 to 5,000. If the content of adhesive functional groups is within the above range, the adhesion to the current collector and the electrode active material layer is further improved.

[0029] The content of adhesive functional groups can be measured by methods such as nuclear magnetic resonance (NMR) analysis and infrared absorption spectroscopy. For example, as described in Japanese Patent Application Publication No. 2007-314720, the proportion (mol%) of units having adhesive functional groups among all units constituting the fluorine-containing copolymer can be determined using methods such as infrared absorption spectroscopy, and the content of adhesive functional groups can be calculated from this proportion.

[0030] Adhesive functional groups are preferably present in at least one of the terminal groups and pendant groups of the main chain of copolymer A, from the viewpoint of adhesion to the current collector and electrode active material layer. Copolymer A, in which adhesive functional groups are present on at least one of the terminal groups and pendant groups of the main chain, can be produced by methods such as copolymerizing monomers having adhesive functional groups during monomer polymerization, or by polymerizing monomers using chain transfer agents or polymerization initiators that provide adhesive functional groups. These methods can also be used in combination. In particular, it is preferable to produce a copolymer having monomer units by copolymerizing monomers having adhesive functional groups, thereby obtaining copolymer A in which adhesive functional groups exist at least as pendant groups of the main chain.

[0031] As monomers having adhesive functional groups, monomers having carbonyl-containing groups, hydroxyl groups, epoxy groups, amide groups, amino groups, or isocyanate groups are preferred, monomers having carbonyl-containing groups are more preferred, cyclic hydrocarbon monomers having acid anhydride groups (hereinafter also referred to as "acid anhydride monomers") and monomers having carboxyl groups are more preferred, and acid anhydride monomers are particularly preferred.

[0032] Examples of acid anhydride monomers include itaconic anhydride (hereinafter also referred to as "IAH"), citraconic anhydride (hereinafter also referred to as "CAH"), 5-norbornene-2,3-dicarboxylic acid anhydride (hereinafter also referred to as "NAH"), and maleic anhydride. Two or more acid anhydride monomers may be used in combination.

[0033] Preferred acid anhydride monomers are IAH, CAH, and NAH. Using any of IAH, CAH, or NAH allows for the easy production of copolymer A having acid anhydride groups without requiring the special polymerization method necessary when using maleic anhydride (see Japanese Patent Publication No. 11-193312). As acid anhydride monomers, IAH and NAH are particularly preferred because they exhibit even better adhesion to the current collector and electrode active material layer.

[0034] Furthermore, when using acid anhydride monomers, hydrolysis of some of the acid anhydride groups in the monomer may result in copolymer A containing units based on dicarboxylic acids (such as itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, and maleic acid) corresponding to the acid anhydride monomer.

[0035] Examples of monomers containing a carboxyl group include maleic acid, itaconic acid, citraconic acid, and undecylenic acid. Examples of monomers having a hydroxyl group include hydroxyalkyl vinyl ethers. Examples of monomers having an epoxy group include epoxyalkyl vinyl ethers.

[0036] When copolymer A has units based on monomers having adhesive functional groups, the proportion of such units is preferably 0.01 to 5.0 mol%, more preferably 0.05 to 3.0 mol%, and even more preferably 0.1 to 2.0 mol%, relative to the total number of monomer-based units in copolymer A. If the proportion of units based on monomers having adhesive functional groups is 0.01 mol% or more, adhesion to the current collector and electrode active material layer is excellent. Adhesion is even better at 0.05 mol% or more, and even better at 0.1 mol% or more. If the proportion of units based on monomers having adhesive functional groups is 5.0 mol% or less, chemical resistance and oxidation resistance are excellent. Chemical resistance and oxidation resistance are even better at 3.0 mol% or less, and even better at 2.0 mol% or less.

[0037] Preferred chain transfer agents that provide adhesive functional groups include those having carboxyl groups, ester bonds, hydroxyl groups, etc. Specifically, examples include acetic acid, acetic anhydride, methyl acetate, ethylene glycol, and propylene glycol. As polymerization initiators that provide adhesive functional groups, peroxide polymerization initiators such as peroxycarbonates, diacylperoxides, and peroxyesters are preferred. Specifically, examples include di-n-propyl peroxydicarbonate, diisopropyl peroxycarbonate, tert-butyl peroxyisopropyl carbonate, bis(4-tert-butylcyclohexyl) peroxydicarbonate, and di-2-ethylhexyl peroxydicarbonate.

[0038] The copolymer A used as a primer is preferably in particulate form because it has excellent miscibility with other components such as conductive materials. When it is in particulate form, the average particle size is preferably 0.01 to 50 μm, and more preferably 0.01 to 20 μm. A particle size of 0.01 μm or larger makes it easy to function as a binder for other components such as conductive materials. A particle size of 50 μm or smaller results in excellent miscibility with other components such as conductive materials. The particulate copolymer A may be dispersed in a liquid medium or in powder form.

[0039] Copolymer A preferably has a melting point of 150°C or higher, more preferably 160 to 320°C, and even more preferably 180 to 260°C. A melting point of 150°C or higher ensures that the material maintains its functionality even at high temperatures. A melting point of 20°C or lower results in excellent processability.

[0040] The MFR of copolymer A is preferably 0.1 to 200, and more preferably 1 to 100. An MFR of 0.1 or higher results in excellent moldability. An MFR of 200 or lower results in excellent mechanical strength of the primer and excellent adhesion to the electrode active material layer and current collector.

[0041] Copolymer A can be produced by conventional methods. For example, it can be produced by polymerizing TFE, ethylene, and an acid anhydride monomer. When polymerization of monomers, it is preferable to use a radical polymerization initiator. Polymerization methods include bulk polymerization, solution polymerization using organic solvents (fluorinated hydrocarbons, chlorinated hydrocarbons, fluorinated chlorinated hydrocarbons, alcohols, hydrocarbons, etc.), suspension polymerization using an aqueous medium and, if necessary, a suitable organic solvent, and emulsion polymerization using an aqueous medium and an emulsifier, with solution polymerization being preferred.

[0042] When polymerizing TFE with ethylene and acid anhydride monomers, the concentration of the acid anhydride monomer during polymerization is preferably 0.01 to 5 mol%, more preferably 0.1 to 3 mol%, and even more preferably 0.1 to 2 mol% relative to the total monomers. If the concentration of the acid anhydride monomer is within the above range, the polymerization rate will be appropriate. If the concentration of the acid anhydride monomer is too high, the polymerization rate tends to decrease. It is preferable to continuously or intermittently supply the amount of acid anhydride monomer consumed during polymerization to the polymerization tank to maintain the concentration of acid anhydride monomer within the aforementioned range.

[0043] [Other polymers] The primer of the present invention may contain polymers other than copolymer A that have the function of a primer, as long as they do not impair the effects of the present invention. Examples of polymers other than copolymer A include polytetrafluoroethylene, tetrafluoroethylene-propylene copolymer, polyimide, polyamideimide, polyetherimide, polyetheretherketone, polyetherketoneketone, polyphenylene sulfide, polyethersulfone, polysulfone, polyamide, polyphenylene ether, polymethacrylate, polymethyl methacrylate, polyacrylonitrile, and polycarbonate.

[0044] When the primer of the present invention contains polymers other than copolymer A, the proportion of copolymer A in the total polymer is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. If the proportion of copolymer A is 50% by mass or more, the effects of the present invention can be easily obtained.

[0045] The primer of the present invention may contain polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, or tetrafluoroethylene-vinylidene fluoride copolymer as polymers other than copolymer A, but it is preferable that they are not included. If the primer of the present invention contains polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, or tetrafluoroethylene-vinylidene fluoride copolymer, the total amount is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less.

[0046] [Conductive material] The primer of the present invention preferably contains a conductive material. By including a conductive material, the increase in the internal resistance of the secondary battery can be suppressed. Examples of conductive materials include acetylene black, Ketjen black, carbon black, graphite, vapor-grown carbon fibers, and conductive carbon such as carbon nanotubes.

[0047] The content of the conductive material in the primer is preferably 30 to 95% by mass, and more preferably 45 to 85% by mass, relative to the total solid content of the primer. When the conductive material content is above a preferred lower limit, conductivity is improved, and the battery's function is enhanced. When the conductive material content is below a preferred upper limit, adhesion to the current collector and electrode active material layer is excellent.

[0048] [Additives] The primer of the present invention may contain various known additives. Examples of additives include emulsifiers, defoamers, leveling agents, preservatives, pH adjusters, dispersants such as cellulose resins, acrylic resins, urethane resins, and urea resins, radical scavengers such as hindered amine light stabilizers (HALS), and acid acceptors such as magnesium oxide and calcium hydroxide.

[0049] <Composition for forming a primer layer> The copolymer A, which is the primer of the present invention, and any other polymers, conductive materials, and additives contained therein are preferably dispersed or dissolved in a liquid medium and used for primer layer formation. The primer layer formation composition of the present invention is a composition comprising the primer of the present invention and a liquid medium. Furthermore, the primer layer obtained using the primer layer forming composition of the present invention does not contain a liquid medium. In addition, the primer layer in the electrode for the energy storage device described later can also be manufactured without using a liquid medium.

[0050] There are no particular limitations on the type of liquid medium, but it is preferable that the liquid medium be selected from the group consisting of aqueous media, aliphatic compounds, aromatic hydrocarbons, alcohols, ethers, esters, ketones, nitrogen-containing compounds, sulfur-containing compounds, and fluorine-containing compounds. It is even more preferable that the liquid medium be selected from the group consisting of aqueous media, N-methylpyrrolidone, N,N-dimethylacetamide, and aliphatic hydrocarbon compounds having 6 to 10 carbon atoms and one carbonyl group (hereinafter also referred to as "carbonyl group-containing aliphatic compounds"). Furthermore, the liquid medium may be a mixed liquid medium consisting of two or more liquid media.

[0051] Aliphatic and aromatic hydrocarbon compounds include hexane, heptane, octane, cyclohexane, methylcyclohexane, ethylcyclohexane, benzene, ethylbenzene, diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymene, and mesitylene.

[0052] Examples of alcohols include methanol, ethanol, isopropanol, butanol, cyclohexanol, phenol, ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol.

[0053] Examples of ethers include diethyl ether, tetrahydrofuran, dioxane, anisole, ethyl benzyl ether, cresyl methyl ether, diphenyl ether, dibenzyl ether, phenethole, butylphenyl ether, methyl monoglycidyl ether, ethyl monoglycidyl ether, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, propylene glycol monomethyl ether, and propylene glycol dimethyl ether.

[0054] Examples of esters include cyclohexyl acetate, ethyl 3-ethoxypropionate, dioxane, methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol monoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoacetate, diethylene glycol diethyl ether, propylene glycol monoacetate, dipropylene glycol monoacetate, propylene glycol diacetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate.

[0055] Examples of ketones include γ-butyrolactone, acetone, methyl ethyl ketone, 2-heptanone, cycloheptanone, cyclohexanone, methyl-n-pentyl ketone, methyl isobutyl ketone, and methyl isopentyl ketone. Examples of nitrogen-containing compounds include dimethylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone.

[0056] Dimethyl sulfoxide is an example of a sulfur-containing compound. Examples of fluorine-containing compounds include perfluorocarbons, hydrofluoroethers, hydrochlorofluorocarbons, hydrofluorocarbons, and fluoropolyethers.

[0057] Examples of aqueous media include water and water containing water-soluble organic solvents. Water-soluble organic solvents are organic solvents that can be miscible with water in any proportion. Preferred water-soluble organic solvents include the aforementioned alcohols (excluding ether alcohols), the aforementioned ether alcohols, and aprotic polar solvents.

[0058] Examples of aprotic polar solvents include N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran (hereinafter also referred to as "THF"), acetonitrile, acetone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 3-methoxy-3-methyl-1-butanol, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.

[0059] When the liquid medium is an aqueous medium, ether alcohols are preferred as the water-soluble organic solvent because they improve the compatibility between copolymer A and the aqueous medium, making it easier to form a uniform film on the article. Dipropylene glycol, tripylene glycol, and dipropylene glycol monomethyl ether are more preferred. When the aqueous medium is water containing a water-soluble organic solvent, the content of the water-soluble organic solvent is preferably 1 to 80 parts by mass, and more preferably 5 to 60 parts by mass, per 100 parts by mass of water.

[0060] A carbonyl group-containing aliphatic compound can be used without practical problems as long as it is a liquid at the temperature at which copolymer A, etc., is dispersed or dissolved, but it is preferable that it be a liquid at room temperature. The melting point of the carbonyl group-containing aliphatic compound is preferably 230°C or lower. The molecular structure of the carbonyl group-containing aliphatic compound is not particularly limited; for example, the carbon skeleton may be linear, branched, or cyclic, and it may have etheric oxygen between the carbon-carbon bonds constituting the main chain or side chains, and some of the hydrogen atoms bonded to carbon atoms may be substituted with halogen atoms such as fluorine atoms.

[0061] Specific examples of carbonyl group-containing aliphatic compounds include ketones such as cyclic ketones and linear ketones, esters such as linear esters and glycol monoesters, and carbonates. Of these, cyclic ketones are more preferred. Two or more of these may be used in combination.

[0062] Below are some more specific examples of the compounds exemplified above as carbonyl group-containing aliphatic compounds preferably used in the present invention.

[0063] Specific examples of the above cyclic ketones include 2-propylcyclopropanone, 2-isopropylcyclopropanone, 2,2,3-trimethylcyclopropanone, 2-ethyl-3-methylcyclopropanone, 2-butylcyclopropanone, 2-isobutylcyclopropanone, 2-tert-butylcyclopropanone, 2-methyl-3-propylcyclopropanone, 2-methyl-3-isopropylcyclopropanone, 2-ethyl-3,3-dimethylcyclopropanone, 2,2,3,3-tetramethylcyclopropanone, 2-pentylcyclopropanone, and 2-isopentyl Cyclopropanone, 2-butyl-3-methylcyclopropanone, 2-ethyl-3-propylcyclopropanone, 2-hexylcyclopropanone, 2-methyl-3-pentylcyclopropanone, 2-butyl-3-ethylcyclopropanone, 2,3-dipropylcyclopropanone, 2-heptylcyclopropanone, 2-hexyl-3-methylcyclopropanone, 2-ethyl-3-pentylcyclopropanone, 2-butyl-3-propylcyclopropanone, 2-ethylcyclobutanone, 3-ethylcyclobutanone, 2,2-dimethylcyclobutanone, 2,3-dimethylcyclopropanone Dimethylcyclobutanone, 3,3-dimethylcyclobutanone, 2,4-dimethylcyclobutanone, 2-propylcyclobutanone, 3-propylcyclobutanone, 2-isopropylcyclobutanone, 3-isopropylcyclobutanone, 2,2,3-trimethylcyclobutanone, 2,3,3-trimethylcyclobutanone, 2,3,4-trimethylcyclobutanone, 2,2,4-trimethylcyclobutanone, 2-butylcyclobutanone, 2-isobutylcyclobutanone, 2-tert-butylcyclobutanone, 3-butylcyclobutanone, 3-isobutylcyclobutanone , 3-tert-butylcyclobutanone, 2-pentylcyclobutanone, 3-pentylcyclobutanone, 2-isopentylcyclobutanone, 3-isopentylcyclobutanone, 2-hexylcyclobutanone, 3-hexylcyclobutanone, 2-methylcyclopentanone, 3-methylcyclopentanone, 2-ethylcyclopentanone, 3-ethylcyclopentanone, 2,2-dimethylcyclopentanone, 2,3-dimethylcyclopentanone, 3,3-dimethylcyclopentanone, 2,5-dimethylcyclopentanone, 2,4-dimethylcyclopentanone, 3,4-dimethylcyclopentanone, 2-propylcyclopentanone, 2-isopropylcyclopentanone, 3-propylcyclopentanone, 3-isopropylcyclopentanone, 2,2,5-trimethylcyclopentanone, 2-butylcyclopentanone, 2-isobutylcyclopentanone, 2-tert-butylcyclopentanone, 3-butylcyclopentanone, 3-isobutylcyclopentanone, 3-tert-butylcyclopentanone, 2,2,5,5-tetramethylcyclopentanone, 2-pentylcyclopentanone, 2-isopentylcyclopentanone Pentanone, 3-pentylcyclopentanone, 3-isopentylcyclopentanone, cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclopentanone, 2-ethylcyclohexanone, 3-ethylcyclohexanone, 4-ethylcyclohexanone, 2,2-dimethylcyclohexanone, 2,3-dimethylcyclohexanone, 2,4-dimethylcyclohexanone, 2,5-dimethylcyclohexanone, 2,6-dimethylcyclohexanone, 2-propylcyclohexanone, 2-isopropylcyclohexanone, 3 -Propylcyclohexanone, 3-isopropylcyclohexanone, 4-propylcyclohexanone, 4-isopropylcyclohexanone, 2,2,6-trimethylcyclohexanone, 2,2,4-trimethylcyclohexanone, 2,4,4-trimethylcyclohexanone, 3,3,5-trimethylcyclohexanone, 2,4,6-trimethylcyclohexanone, 2-butylcyclohexanone, 2-isobutylcyclohexanone, 2-tert-butylcyclohexanone, 3-butylcyclohexanone, 3-isobutylcyclohexanone, 3-tert -Butylcyclohexanone, 4-Butylcyclohexanone, 4-Isobutylcyclohexanone, 4-Tert-Butylcyclohexanone, 2,2-Diethylcyclohexanone, 2,4-Diethylcyclohexanone, 2,6-Diethylcyclohexanone, 3,5-Diethylcyclohexanone, 2,2,6,6-Tetramethylcyclohexanone, Cycloheptanone, 2-Methylcycloheptanone, 3-Methylcycloheptanone, 4-Methylcycloheptanone, 2-Ethylcycloheptanone, 3-Ethylcycloheptanone, 4-Ethylcycloheptanone, 2,2-dimethylcycloheptanone, 2,7-dimethylcycloheptanone, 2-propylcycloheptanone, 2-isopropylcycloheptanone, 3-propylcycloheptanone, 3-isopropylcycloheptanone, 4-propylcycloheptanone, 4-isopropylcycloheptanone, 2,2,7-trimethylcycloheptanone, cyclooctanone, 2-methylcyclooctanone, 3-methylcyclooctanone, 4-methylcyclooctanone, 5-methylcyclooctanone, 2-ethylcyclooctanone, 3-ethylcyclooctanone, 4- Examples include ethylcyclooctanone, 5-ethylcyclooctanone, 2,2-dimethylcyclooctanone, 2,8-dimethylcyclooctanone, cyclononanone, 2-methylcyclononanone, 3-methylcyclononanone, 4-methylcyclononanone, 5-methylcyclononanone, cyclodecanone, isophorone, (-)-fencone ((1R,4S)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-one), (+)-fencone ((1S,4R)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-one)), etc.

[0064] Specific examples of the aforementioned chain-like ketones include 2-hexanone, 3-hexanone, methyl isobutyl ketone, ethyl isopropyl ketone, 3,3-dimethyl-2-butanone, 2-heptanone, 3-heptanone, 4-heptanone, diisopropyl ketone, 5-methyl-2-hexanone, 2-octanone, 3-octanone, 4-octanone, 5-methyl-3-heptanone, 2-nonanone, 3-nonanone, 4-nonanone, 5-nonanone, diisobutyl ketone, 2-decanone, 3-decanone, 4-decanone, and 5-decanone.

[0065] Specific examples of the aforementioned chain-like esters include pentyl formate, isopentyl formate, cyclopentyl formate, hexyl formate, cyclohexyl formate, heptyl formate, octyl formate, 2-ethylhexyl formate, nonyl formate, butyl acetate, isobutyl acetate, sec-butyl acetate, tert-butyl acetate, pentyl acetate, isopentyl acetate, cyclopentyl acetate, hexyl acetate, cyclohexyl acetate, heptyl acetate, octyl acetate, 2-ethylhexyl acetate, propyl propionate, isopropyl propionate, propio Butyl butyrate, isobutyl propionate, sec-butyl propionate, tert-butyl propionate, pentyl propionate, isopentyl propionate, cyclopentyl propionate, hexyl propionate, cyclohexyl propionate, heptyl propionate, 2,2,3,3,3-pentafluoropropyl propionate, 2,2,3,3-tetrafluoropropyl propionate, ethyl butyrate, propyl butyrate, isopropyl butyrate, butyl butyrate, isobutyl butyrate, sec-butyl butyrate, te rt-butyl, pentyl butyrate, isopentyl butyrate, cyclopentyl butyrate, hexyl butyrate, cyclohexyl butyrate, 2,2,2-trifluoroethyl butyrate, 2,2,3,3,3-pentafluoropropyl butyrate, 2,2,3,3-tetrafluoropropyl butyrate, ethyl isobutyrate, propyl isobutyrate, isopropyl isobutyrate, butyl isobutyrate, isobutyl isobutyrate, sec-butyl isobutyrate, tert-butyl isobutyrate, pentyl isobutyrate, isopentyl isobutyrate, cyclopentyl isobutyrate, hexyl isobutyrate , cyclohexyl isobutyrate, 2,2,2-trifluoroethyl isobutyrate, 2,2,3,3,3-pentafluoropropyl isobutyrate, 2,2,3,3-tetrafluoropropyl isobutyrate, methyl valerate, ethyl valerate, propyl valerate, isopropyl valerate, butyl valerate, isobutyl valerate, sec-butyl valerate, tert-butyl valerate, pentyl valerate, isopentyl valerate, 2,2,2-trifluoroethyl valerate, 2,2,3,3,3-pentafluoropropyl valerate, 2,2,3,3-Tetrafluoropropyl, Methyl Isovalerate, Ethyl Isovalerate, Propyl Isovalerate, Isopropyl Isovalerate, Butyl Isovalerate, Isobutyl Isovalerate, sec-Butyl Isovalerate, tert-Butyl Isovalerate, Pentyl Isovalerate, Isopentyl Isovalerate, 2,2,2-Trifluoroethyl Isovalerate, 2,2,3,3,3-Pentafluoropropyl Isovalerate, 2,2,3,3-Tetrafluoropropyl Isovalerate, Methyl Pivalate, Piva Ethyl pivalate, propyl pivalate, isopropyl pivalate, butyl pivalate, isobutyl pivalate, sec-butyl pivalate, tert-butyl pivalate, pentyl pivalate, isopentyl pivalate, 2,2,2-trifluoroethyl pivalate, 2,2,3,3,3-pentafluoropropyl pivalate, 2,2,3,3-tetrafluoropropyl pivalate, methyl hexanoate, ethyl hexanoate, propyl hexanoate, isopropyl hexanoate, butyl hexanoate Isobutyl hexanoate, sec-butyl hexanoate, tert-butyl hexanoate, 2,2,2-trifluoroethyl hexanoate, 2,2,3,3,3-pentafluoropropyl hexanoate, 2,2,3,3-tetrafluoropropyl hexanoate, methyl heptanoate, ethyl heptanoate, propyl heptanoate, isopropyl heptanoate, 2,2,2-trifluoroethyl heptanoate, 2,2,3,3,3-pentafluoropropyl heptanoate, 2,2,3,3-tetrafluoropropyl heptanoate, methyl cyclohexanecarboxylate, ethyl cyclohexanecarboxylate, propyl cyclohexanecarboxylate, isopropyl cyclohexanecarboxylate, 2,2,2-trifluoroethyl cyclohexanecarboxylate, 2,2,3,3,3-pentafluoropropyl cyclohexanecarboxylate, 2,2,3,3-tetrafluoropropyl cyclohexanecarboxylate, methyl octanoate, ethyl octanoate, 2,2,Examples include 2-trifluoroethyl, methyl nonanoate, butyl trifluoroacetate, pentyl trifluoroacetate, hexyl trifluoroacetate, heptyl trifluoroacetate, octyl trifluoroacetate, propyl pentafluoropropionate, butyl pentafluoropropionate, pentyl pentafluoropropionate, hexyl pentafluoropropionate, heptyl pentafluoropropionate, ethyl perfluorobutanoate, propyl perfluorobutanoate, butyl perfluorobutanoate, pentyl perfluorobutanoate, hexyl perfluorobutanoate, methyl perfluoropentanoate, ethyl perfluoropentanoate, propyl perfluoropentanoate, butyl perfluoropentanoate, methyl perfluorohexanoate, ethyl perfluorohexanoate, propyl perfluorohexanoate, butyl perfluorohexanoate, methyl perfluoroheptanoate, ethyl perfluoroheptanoate, propyl perfluoroheptanoate, methyl perfluorooctanoate, ethyl perfluorooctanoate, etc.

[0066] Specific examples of the monoesters of the glycols mentioned above include 2-ethoxyethyl acetate, 2-propoxyethyl acetate, 2-butoxyethyl acetate, 2-pentyloxyethyl acetate, 2-hexyloxyethyl acetate, 1-methoxy-2-acetoxypropane, 1-ethoxy-2-acetoxypropane, 1-propoxy-2-acetoxypropane, 1-butoxy-2-acetoxypropane, 1-pentyloxy-2-acetoxypropane, 3-methoxybutyl acetate, 3-ethoxybutyl acetate, 3-propoxybutyl acetate, 3-butoxybutyl acetate, 3-methoxy-3-methylbutyl acetate, 3-ethoxy-3-methylbutyl acetate, 3-propoxy-3-methylbutyl acetate, 4-methoxybutyl acetate, 4-ethoxybutyl acetate, 4-propoxybutyl acetate, and 4-butoxybutyl acetate.

[0067] Specific examples of the aforementioned carbonates include butylmethyl carbonate, ethyl propyl carbonate, dipropyl carbonate, diisopropyl carbonate, butyl propyl carbonate, butyl isopropyl carbonate, isobutyl propyl carbonate, tert-butyl propyl carbonate, tert-butyl isopropyl carbonate, dibutyl carbonate, diisobutyl carbonate, ditert-butyl carbonate, bis(2,2,3,3,3-pentafluoropropyl) carbonate, bis(2,2,3,3-tetrafluoropropyl) carbonate, bis(1,1,1,3,3,3-hexafluoroisopropyl) carbonate, bis(2,2,3,3,4,4,4-heptafluorobutyl) carbonate, and bis(perfluoro-tert-butyl) carbonate.

[0068] The total content of copolymer A and other polymers as needed in the primer layer forming composition (polymer concentration) is more preferably 5 to 70% by mass, even more preferably 7 to 60% by mass, and particularly preferably 9 to 55% by mass, relative to the total amount of the primer layer forming composition. If the content is above the lower limit of the above range, excellent adhesion to the current collector and electrode active material layer is achieved. If the content is below the upper limit of the above range, conductivity is improved, and the function as a battery is enhanced.

[0069] The solid content concentration of the primer layer forming composition is more preferably 1 to 50% by mass, even more preferably 3 to 40% by mass, and particularly preferably 5 to 30% by mass, relative to the total amount of the primer layer forming composition, in order to allow the primer layer forming composition to be applied thinly.

[0070] When the primer layer forming composition contains a conductive material, the solid content concentration of the primer layer forming composition is more preferably 3 to 60% by mass, and even more preferably 5 to 50% by mass, based on the total amount of the primer layer forming composition. In this case, the polymer concentration in the primer layer forming composition is more preferably 3 to 60% by mass, and even more preferably 5 to 50% by mass, based on the total amount of solid content.

[0071] <Electrode mixture for energy storage devices> The electrode mixture for obtaining electrodes for energy storage devices of the present invention (hereinafter also simply referred to as "electrode mixture") contains a binder and an electrode active material. A conductive material may be included as needed, and other components may also be included.

[0072] The binder used in the present invention is not particularly limited, and known binders can be used as appropriate. In particular, a binder in which at least a portion of the polymer component is a fluorine-containing polymer is preferred because the usefulness of the effect obtained by the primer of the present invention is high. The binder used in the present invention preferably contains copolymer A, similar to the primer of the present invention. The preferred embodiment of the binder used in the present invention is the same as the preferred embodiment of the primer of the present invention.

[0073] The electrode active material used in the present invention is not particularly limited, and known materials can be used as appropriate. The positive electrode active materials are MnO2, V2O5, and V6O 13 Metal oxides such as TiS2, MoS2, FeS and other metal sulfides, LiCoO2, LiNiO2, LiMn2O4, LiNi 0.8 Co 0.15 Al 0.05 O2, LiLiLi 1 / 3 Co 1 / 3 Mn 1 / 3 Examples include lithium composite metal oxides containing transition metals such as Co, Ni, Mn, Fe, and Ti, such as O2 and LiFePO4, and compounds in which some of the transition metal elements in these compounds are substituted with other metal elements. Furthermore, conductive polymer materials such as polyacetylene and poly-p-phenylene can also be used. In addition, materials in which carbon materials or inorganic compounds are coated on part or all of the surface can also be used.

[0074] Examples of negative electrode active materials include carbonaceous materials such as coke, graphite, mesophase pitch spheres, phenolic resins, carbides of polymer compounds such as poly(p-phenylene), gas-phase generated carbon fibers, and carbon fibers. Also, metals such as Si, Sn, Sb, Al, Zn, and W that can be alloyed with lithium are also possible, such as silicon monoxide, which has the general formula SiO₂. x Examples include silicon oxides represented by (where x is preferably between 0.5 and 1.5). Electrode active materials can also be those with a conductive material attached to their surface by mechanical modification or other methods. In the case of electrode mixtures for lithium-ion secondary batteries, the electrode active material used can be any material that can reversibly insert and release lithium ions by applying an electric potential in the electrolyte, and can be either an inorganic or organic compound.

[0075] In particular, it is preferable to include a conductive material in the electrode mixture used in the manufacture of the positive electrode. By including a conductive material, the electrical contact between the electrode active materials is improved, the electrical resistance within the active material layer can be reduced, and the discharge rate characteristics of the non-aqueous secondary battery can be improved. Examples of conductive materials include acetylene black, Ketjen black, carbon black, graphite, vapor-grown carbon fibers, and conductive carbon such as carbon nanotubes. It is preferable for the electrode mixture to contain a conductive material, as the effect of reducing electrical resistance becomes greater with the addition of a small amount of conductive material.

[0076] Other components known to be used in electrode mixtures may be used. Specific examples include water-soluble polymers such as carboxymethylcellulose, polyvinyl alcohol, polyacrylic acid, and polymethacrylic acid. The total proportion of polymers in the electrode mixture (the total of copolymer A and any other polymers included as needed) is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, and particularly preferably 1 to 8 parts by mass, per 100 parts by mass of the electrode active material. Furthermore, if the electrode mixture contains a conductive material, the proportion of the conductive material in the electrode mixture is more than 0 parts by mass, preferably 20 parts by mass or less, more preferably 1 to 10 parts by mass, and particularly preferably 3 to 8 parts by mass, relative to 100 parts by mass of the electrode active material. When the electrode mixture contains a liquid medium, the solid content concentration in the electrode mixture is preferably 30 to 95% by mass, more preferably 35 to 90% by mass, and particularly preferably 40 to 85% by mass.

[0077] <Electrodes for energy storage devices> The electrode for a power storage device of the present invention is an electrode for a power storage device having a current collector and an electrode active material layer formed on the current collector, wherein a primer layer containing the primer for a power storage device electrode of the present invention is provided between the current collector and the electrode active material layer. The current collector is not particularly limited as long as it is made of a conductive material, but generally, examples include metal foils, metal meshes, and porous metals made of aluminum, nickel, stainless steel, copper, etc. Aluminum is preferably used as the positive electrode current collector, and copper is preferably used as the negative electrode current collector. The thickness of the current collector is preferably 1 to 100 μm.

[0078] The electrode for the energy storage device is obtained by forming a primer layer on at least one side, preferably both sides, of a current collector using copolymer A, which is the primer of the present invention, and then forming an electrode active material layer on the primer layer using an electrode mixture.

[0079] The primer layer is obtained, for example, by applying the primer-forming composition of the present invention to at least one side, preferably both sides, of a current collector and removing the liquid medium in the primer composition by drying. If necessary, the dried primer layer may be pressed to form it to the desired thickness. Furthermore, a primer layer can be formed without using a liquid medium by using a powder consisting of particles of copolymer A, which is the primer of the present invention.

[0080] There are no particular limitations on the thickness of the primer layer, but it is preferably 0.1 to 100 μm, and more preferably 0.5 to 50 μm. If the primer layer thickness is above the lower limit of the preferred range, the adhesion of the electrode mixture to the current collector will be excellent. If the primer layer thickness is below the upper limit of the preferred range, the conductivity will improve, and the function of the battery will be enhanced.

[0081] The electrode active material layer can be obtained, for example, by applying an electrode mixture containing a liquid medium onto a primer layer formed on a current collector, and then removing the liquid medium by drying. If necessary, the dried electrode active material layer may be pressed to form it to the desired thickness. Alternatively, the electrode active material layer can be formed without using a liquid medium by using a powdered electrode mixture that does not contain a liquid medium.

[0082] The application amount of electrode mixtures containing liquid media, calculated based on solid content, is 1 to 3000 g / m². 2 It is preferable to have 5-1000g / m² 2 It is more preferable that the amount of electrode mixture applied is above the lower limit of the preferred range, thereby improving the battery's function. The battery size can be reduced if the amount of electrode mixture applied is below the upper limit of the preferred range. The thickness of the electrode active material layer is preferably 1 to 500 μm, and more preferably 5 to 300 μm. When the thickness of the electrode active material layer is above the lower limit of the preferred range, the battery function is improved. When the thickness of the electrode active material layer is below the upper limit of the preferred range, the battery size can be reduced.

[0083] Various coating methods can be used to apply the primer layer-forming composition and the electrode mixture containing the liquid medium. Examples include the doctor blade method, dip method, reverse roll method, direct roll method, gravure method, extrusion method, and brush coating method. The coating temperature is not particularly limited, but is usually preferred to be around room temperature. Drying can be performed using various drying methods, such as drying with hot air, hot air, low humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams. The drying temperature is not particularly limited, but is usually preferred to be between room temperature and 200°C in heated vacuum dryers, etc. Pressing can be performed using a die press or a roll press, etc.

[0084] In the case of the primer of the present invention, which does not contain a liquid medium, a powder consisting of particles of copolymer A, which is the primer, can be placed on the current collector and a primer layer can be formed by calendering. Alternatively, a film for forming an undercoat layer can be created by calendering and then laminated onto the current collector. If the binder for the energy storage device is a dry binder that does not contain a liquid medium, the electrode mixture can be placed on a primer layer formed on the current collector, and the electrodes can be formed by calendering. Alternatively, an electrode film can be created by calendering the electrode mixture, and then laminated onto the primer layer formed on the current collector.

[0085] <Energy storage devices> The primer composition for electrodes of the energy storage device of the present invention and the energy storage device using the electrodes for the energy storage device have at least one pair of electrodes and an electrolyte interposed between the pair of electrodes. Furthermore, if the electrolyte is liquid, it is preferable to include a separator. Energy storage devices are not particularly limited, but examples include batteries, electrochemical sensors, electrochromic elements, electrochemical switching elements, electrolytic capacitors, and electrochemical capacitors.

[0086] The battery is not particularly limited as long as it has electrodes and an electrolyte, but examples include alkali metal batteries, alkali metal ion batteries, alkaline earth metal ion batteries, radical batteries, solar cells, and fuel cells. In a preferred embodiment, the battery is particularly an alkali metal battery, an alkali metal ion battery, or an alkaline earth metal battery, and may be, for example, a lithium battery, a lithium ion battery, a sodium ion battery, a magnesium battery, a lithium-air battery, a sodium-sulfur battery, or a lithium-sulfur battery, and preferably a lithium-ion battery. The battery may be a primary battery or a secondary battery, and is preferably a secondary battery. The present invention also relates to a secondary battery comprising electrodes and an electrolyte for the energy storage device. Preferably, the secondary battery is an alkali metal ion secondary battery, and more particularly, a lithium ion secondary battery. The following provides a detailed explanation of lithium-ion rechargeable batteries.

[0087] <Lithium-ion rechargeable battery> A lithium-ion secondary battery as an energy storage device comprises the electrodes for energy storage devices of the present invention as at least one of the positive and negative electrodes, and also includes an electrolyte. Furthermore, if the electrolyte is liquid, it is preferable to include a separator. The electrolyte contains an electrolyte and a solvent. Suitable solvents include aprotic organic solvents such as alkyl carbonates (DMC, ethylene carbonate, DEC, propylene carbonate, PC, butylene carbonate, and methyl ethyl carbonate), esters (γ-butyrolactone, methyl formate, ethers (1,2-dimethoxyethane, tetrahydrofuran, etc.), sulfur compounds (sulfolane, dimethyl sulfoxide, etc.). Dimethyl carbonate, ethylene carbonate, propylene carbonate, diethyl carbonate, and methyl ethyl carbonate are particularly preferred due to their high ionic conductivity and wide operating temperature range. These can be used individually or in combination of two or more. Examples of electrolytes include lithium salts such as LiClO4, LiBF4, LiPF6, LiAsF5, CF3SO3Li, (CF3SO2)2NLi, and (FSO2)2NLi.

[0088] <Solid electrolyte> In the battery of this disclosure, a solid electrolyte may be used instead of the liquid electrolyte described above. Examples of solid electrolytes include inorganic electrolytes and organic electrolytes.

[0089] Examples of inorganic electrolytes include oxide-based solid electrolytes, sulfide-based solid electrolytes, and hydride-based solid electrolytes. Examples of oxide-based solid electrolytes include perovskite-type oxides, NASICON-type oxides, LISICON-type oxides, and garnet-type oxides. Examples of sulfide-based solid electrolytes include Li2S-P2S5 compounds, Li2S-SiS2 compounds, Li2S-GeS2 compounds, Li2S-B2S3 compounds, Li2S-P2S3 compounds, LiI-Si2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li 10 GeP2S 12 These are some examples. Examples of hydride-based solid electrolyte materials include LiBH4, LiBH4-3KI, LiBH4-PI2, LiBH4-P2S5, LiBH4-LiNH2, 3LiBH4-LiI, LiNH2, Li2AlH6, Li(NH2)2I, Li2NH, LiGd(BH4)3Cl, Li2(BH4)(NH2), Li3(NH2)I, and Li4(BH4)(NH2)3.

[0090] Examples of organic electrolytes include polymer-based solid electrolytes. Examples of polymer-based solid electrolytes include organic polymer electrolytes such as polymer compounds containing one or more selected from the group consisting of polyoxyethylene-based polymer compounds, polyorganosiloxane chains, and polyoxyalkylene chains. [Examples]

[0091] The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The tests and evaluations in the examples and comparative examples were carried out by the following methods. Examples 1 to 8 are examples, and Examples 9 and 10 are comparative examples.

[0092] <Measurement method> [Melting point (°C)] The endothermic peak was determined using a scanning differential thermal analyzer (SII Corporation, DSC7200) when the sample was heated to 300°C at a rate of 10°C / min in an air atmosphere.

[0093] [Average particle size of powder and D90] Using a laser diffraction / scattering particle size distribution analyzer (LA-920) manufactured by Horiba, Ltd., powder was dispersed in water, the particle size distribution was measured, and the average particle size (μm) and D90 (μm) were calculated.

[0094] [Loosely packed bulk density and densely packed bulk density] The loosely packed bulk density and tightly packed bulk density of the powder were measured using the methods described in International Publication No. 2016 / 017801, sections

[0117] and

[0118] .

[0095] [Content of acid anhydride groups (mol%)] Using a 200 μm thick film obtained by press-molding a fluorine-containing polymer, a Fourier transform infrared spectrometer (Thermo Fisher Scientific, Nicolet iS10) was used to measure 1800-1900 cm². -1 The intensity of absorption originating from acid anhydride groups appearing in the vicinity was measured, and the acid anhydride group content (the proportion of units containing acid anhydride groups among all units constituting the fluorine-containing polymer) was calculated.

[0096] [MFR (Melt Flow Rate)] Using a melt indexer (manufactured by Technoseven Co., Ltd.), the mass (g) of copolymer flowing out of a 2mm diameter, 8mm length orifice in 10 minutes was measured under a load of 49N in accordance with ASTM D3159, and this was defined as MFR (g / 10 min). Measurement temperatures of 220°C, 297°C, or 380°C were used.

[0097] <Copolymer used as primer> The following copolymers were used in powder or dispersion form to form the primer layer. • Copolymer A-1: ​​A copolymer obtained by polymerizing TFE, CF2=CF-O-(CF2)3F, and NAH in the same manner as in Example 5 of WO2015 / 182702 (melting point: 300°C, MFR 25g / 10min at 380°C). • Copolymer A-2: A copolymer obtained by polymerizing TFE, ethylene, CH2=CH(CF2)2F, and IAH in the same manner as in Example 2 of WO2015 / 182702 (melting point: 255°C, MFR 26g / 10min at 297°C). • Copolymer A-3: A copolymer obtained by polymerizing TFE, ethylene, HFP, CH2=CH(CF2)4F, and IAH in the same manner as in Example 3 of WO2015 / 182702 (melting point: 183°C, MFR 11g / 10min at 220°C).

[0098] [Copolymer A-1 (powder)] Copolymer A-1 was ground using a jet mill (Seishin Corporation, single-track jet mill FS-4 type) under conditions of grinding pressure of 0.5 MPa and processing speed of 1 kg / hr to obtain copolymer A-1 (powder). The average particle size of the obtained copolymer A-1 (powder) was 2.58 μm, D90 was 7.1 μm, the loosely packed bulk density was 0.278 g / mL, and the tightly packed bulk density was 0.328 g / mL.

[0099] [Copolymer A-2 (powder)] Copolymer A-2 was pulverized under the same conditions as copolymer A-1 to obtain copolymer A-2 (powder). The average particle size of the obtained copolymer A-2 (powder) was 3.54 μm, D90 was 9.2 μm, the loosely packed bulk density was 0.332 g / mL, and the tightly packed bulk density was 0.395 g / mL.

[0100] [Copolymer A-3 (powder)] Copolymer A-3 was pulverized under the same conditions as copolymer A-1 to obtain copolymer A-3 (powder). The average particle size of the obtained copolymer A-3 (powder) was 2.92 μm, D90 was 8.2 μm, the loosely packed bulk density was 0.313 g / mL, and the tightly packed bulk density was 0.388 g / mL.

[0101] [Copolymer A-3 (DIPK dispersion)] 50 g of copolymer A-3 (powder) and 450 g of diisopropyl ketone (DIPK) were placed in a 1 L glass pressure-resistant reaction vessel equipped with a stirrer. The mixture was heated to 150°C and stirred for 1 hour to disperse the copolymer A-3 (powder). The mixture was then cooled to room temperature while stirring to obtain copolymer A-3 (DIPK dispersion).

[0102] <Example 1> (Composition 1 for primer layer formation) Composition 1 for forming a primer layer, in which copolymer A-1 is dispersed in water, was prepared by mixing the following components in a ball mill for 5 hours. • Carbon powder (specific surface area: 150 m²) 2 / g):40 parts by mass ·Copolymer A-1 (powder): 40 parts by mass Nonionic surfactant (Neos Co., Ltd., F-Tergent 250): 3 parts by mass • Distilled water: 320 parts by mass

[0103] (Preparation of electrolyte solution) An electrolyte was obtained by adding LiPF6 to a mixed solvent (30:70 volume ratio) of ethylene carbonate, a high dielectric constant solvent, and ethyl methyl carbonate, a low viscosity solvent, to a concentration of 1.0 mol / liter.

[0104] (Fabrication of positive electrode laminate and positive electrode) LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 A cathode mixture slurry was prepared by mixing O2, carbon black as the conductive material, and an N-methyl-2-pyrrolidone dispersion of polyvinylidene fluoride (PVdF) as the binder, so that the solid content ratio of the active material, conductive material, and binder was 92 / 3 / 5 (by mass).

[0105] Composition 1 was applied to a 20 μm thick aluminum foil current collector to a dry thickness of 10 μm and dried. Then, the resulting positive electrode mixture slurry was applied on top to a dry thickness of 100 μm and dried. After that, it was compressed and molded using a press to form a positive electrode laminate. The positive electrode laminate was punched out to a diameter of 1.6 cm using a punching machine to produce circular positive electrodes.

[0106] (Fabrication of negative electrode laminate and negative electrode) A negative electrode slurry was prepared by mixing synthetic graphite powder and amorphous silicon (SiO) as the negative electrode active material, an aqueous dispersion of sodium carboxymethylcellulose (1% by mass concentration of sodium carboxymethylcellulose) as the thickener, and an aqueous dispersion of styrene-butadiene rubber (50% by mass concentration of styrene-butadiene rubber) as the binder, with the solid content ratio of the active material, thickener, and binder being 93 / 4.6 / 1.2 / 1.2 (by mass%).

[0107] Composition 1 was applied to a 20 μm thick copper foil to a dry thickness of 10 μm and dried. Then, the resulting negative electrode mixture slurry was applied on top to a dry thickness of 100 μm and dried. After that, it was compressed and molded using a press to form a negative electrode laminate. The negative electrode laminate was punched out to a diameter of 1.6 cm using a punching machine to produce circular negative electrodes.

[0108] (Manufacturing of lithium-ion secondary batteries) The circular positive and negative electrodes described above were placed opposite each other via a 20 μm thick microporous polyethylene film (separator) and housed in a pouch. The electrolyte obtained above was injected into this pouch, and after the electrolyte had sufficiently permeated the separator, etc., it was sealed, pre-charged, and aged to produce a coin-type lithium-ion secondary battery.

[0109] <Example 2> (Composition 2 for primer layer formation) Composition 2 for primer layer formation was prepared by mixing the following components in a ball mill for 5 hours, in which copolymer A-1 was dispersed in N-methylpyrrolidone (NMP). • Carbon powder (specific surface area: 150 m²) 2 / g):40 parts by mass ·Copolymer A-1 (powder): 40 parts by mass Nonionic surfactant (manufactured by Neos, FTX-218P): 3 parts by mass ·NMP: 320 parts by mass

[0110] (Fabrication of positive electrode laminate and positive electrode) A positive electrode laminate and a positive electrode were prepared in the same manner as in Example 1, except that composition 2 was used instead of composition 1.

[0111] (Fabrication of negative electrode laminate and negative electrode) The negative electrode laminate and the negative electrode were prepared in the same manner as in Example 1, except that composition 2 was used instead of composition 1.

[0112] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 1, except that the positive and negative electrodes obtained in Example 2 were used.

[0113] <Example 3> (Composition 3 for primer layer formation) Composition 3 for forming a powdery primer layer using copolymer A-1 was prepared by mixing the following components in a Henschel mixer. • Carbon powder (specific surface area: 150 m² / g): 40 parts by mass ·Fluorine-containing copolymer (A) powder: 40 parts by mass

[0114] (Preparation of electrolyte solution) An electrolyte was obtained by adding LiPF6 to a mixed solvent (30:70 volume ratio) of ethylene carbonate, a high dielectric constant solvent, and ethyl methyl carbonate, a low viscosity solvent, to a concentration of 1.0 mol / liter.

[0115] (Fabrication of positive electrode laminate and positive electrode) A cathode mixture slurry was prepared in the same manner as in Example 1. The obtained composition 3 was calendered to create a 10 μm thick undercoat film. The undercoat film was laminated onto a 20 μm thick aluminum foil current collector, and the obtained positive electrode mixture slurry was then applied on top to a dry thickness of 100 μm. After drying, it was compressed and molded using a press to form a positive electrode laminate. The positive electrode laminate was punched out to a diameter of 1.6 cm using a punching machine to produce circular positive electrodes.

[0116] (Fabrication of negative electrode laminate and negative electrode) A negative electrode mixture slurry was prepared in the same manner as in Example 1. The obtained composition 3 was calendered to create a 10 μm thick undercoat film. The undercoat film was laminated onto a 20 μm thick copper foil, and the obtained negative electrode mixture slurry was then applied to it to a dry thickness of 100 μm. After drying, it was compressed and molded using a press to form a negative electrode laminate. The negative electrode laminate was punched out to a diameter of 1.6 cm using a punching machine to produce circular negative electrode materials.

[0117] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 1, except that the positive and negative electrodes obtained in Example 3 were used.

[0118] <Example 4> (Composition 4 for primer layer formation) A primer layer-forming composition 4 was prepared in which copolymer A-2 (powder) was dispersed in water, in the same manner as in Example 1, except that copolymer A-2 (powder) was used instead of copolymer A-1 (powder).

[0119] (Fabrication of positive electrode laminate and positive electrode) A positive electrode laminate and a positive electrode were prepared in the same manner as in Example 1, except that composition 4 was used instead of composition 1.

[0120] (Fabrication of negative electrode laminate and negative electrode) The negative electrode laminate and the negative electrode were prepared in the same manner as in Example 1, except that composition 4 was used instead of composition 1.

[0121] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 1, except that the positive and negative electrodes obtained in Example 4 were used.

[0122] <Example 5> (Composition 5 for primer layer formation) A powdery primer layer-forming composition 5 was prepared using copolymer A-2 (powder) in the same manner as in Example 3, except that copolymer A-2 (powder) was used instead of copolymer A-1 (powder).

[0123] (Fabrication of positive electrode laminate and positive electrode) A positive electrode laminate and a positive electrode were prepared in the same manner as in Example 3, except that composition 5 was used instead of composition 3.

[0124] (Fabrication of negative electrode laminate and negative electrode) The negative electrode laminate and the negative electrode were prepared in the same manner as in Example 3, except that composition 5 was used instead of composition 3.

[0125] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 3, except that the positive and negative electrodes obtained in Example 5 were used.

[0126] <Example 6> (Composition 6 for primer layer formation) A primer layer-forming composition 6 was prepared in which copolymer A-3 was dispersed in water, in the same manner as in Example 1, except that copolymer A-3 (powder) was used instead of copolymer A-1 (powder).

[0127] (Fabrication of positive electrode laminate and positive electrode) A positive electrode laminate and a positive electrode were prepared in the same manner as in Example 1, except that composition 6 was used instead of composition 1.

[0128] (Fabrication of negative electrode laminate and negative electrode) The negative electrode laminate and the negative electrode were prepared in the same manner as in Example 1, except that composition 6 was used instead of composition 1.

[0129] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 1, except that the positive and negative electrodes obtained in Example 6 were used.

[0130] <Example 7> (Composition 7 for primer layer formation) Composition 7 for primer layer formation was prepared by mixing the following components in a ball mill for 5 hours, in which copolymer A-3 was dispersed in diisopropyl ketone (DIPK). • Carbon powder (specific surface area: 150 m²) 2 / g):10 parts by mass ·Copolymer A-3 (DIPK dispersion): 100 parts by mass

[0131] (Fabrication of positive electrode laminate and positive electrode) A positive electrode laminate and a positive electrode were prepared in the same manner as in Example 1, except that composition 7 was used instead of composition 1.

[0132] (Fabrication of negative electrode laminate and negative electrode) The negative electrode laminate and the negative electrode were prepared in the same manner as in Example 1, except that composition 7 was used instead of composition 1.

[0133] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 1, except that the positive and negative electrodes obtained in Example 7 were used.

[0134] <Example 8> (Composition 8 for primer layer formation) A powdery primer layer-forming composition 8 was prepared in the same manner as in Example 3, except that copolymer A-3 (powder) was used instead of copolymer A-1 (powder).

[0135] (Fabrication of positive electrode laminate and positive electrode) A positive electrode laminate and a positive electrode were prepared in the same manner as in Example 3, except that composition 8 was used instead of composition 3.

[0136] (Fabrication of negative electrode laminate and negative electrode) The negative electrode laminate and the negative electrode were prepared in the same manner as in Example 3, except that composition 8 was used instead of composition 3.

[0137] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 3, except that the positive and negative electrodes obtained in Example 8 were used.

[0138] <Example 9> (Composition 9 for primer layer formation) Composition 9 for forming a polyurethane-based primer layer was prepared by mixing the following components in a ball mill for 5 hours. • Carbon powder (specific surface area: 150 m²) 2 / g):30 parts by mass • Polyurethane (Miractran P490, manufactured by Nippon Miractran Co., Ltd.): 65 parts by mass • Polyisocyanate (Coronate L, manufactured by Tosoh Corporation): 5 parts by mass Methyl ethyl ketone (MEK): 1200 parts by mass; Methyl isobutyl ketone (MIBK): 800 parts by mass

[0139] (Fabrication of positive electrode laminate and positive electrode) A positive electrode laminate and a positive electrode were prepared in the same manner as in Example 1, except that composition 9 was used instead of composition 1.

[0140] (Fabrication of negative electrode laminate and negative electrode) The negative electrode laminate and the negative electrode were prepared in the same manner as in Example 1, except that composition 9 was used instead of composition 1.

[0141] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 1, except that the positive and negative electrodes obtained in Example 9 were used.

[0142] <Example 10> (Composition 10 for primer layer formation) Composition 10 for forming a primer layer containing epoxy resin was prepared by mixing the following components in a ball mill for 5 hours. • Carbon powder (specific surface area: 150 m²) 2 / g):30 parts by mass • Epoxy resin (Epiclon H-205-60KM, manufactured by Dainippon Ink Co., Ltd.: 40 parts by mass) • Polyisocyanate (Coronate L, manufactured by Tosoh Corporation): 5 parts by mass • Silane coupling agent (KBM573, manufactured by Shin-Etsu Chemical Co., Ltd.): 25 parts by mass Methyl ethyl ketone (MEK): 1200 parts by mass; Methyl isobutyl ketone (MIBK): 800 parts by mass

[0143] (Fabrication of positive electrode laminate and positive electrode) A positive electrode laminate and a positive electrode were prepared in the same manner as in Example 3, except that composition 10 was used instead of composition 3.

[0144] (Fabrication of negative electrode laminate and negative electrode) The negative electrode laminate and the negative electrode were prepared in the same manner as in Example 3, except that composition 10 was used instead of composition 3.

[0145] (Manufacturing of lithium-ion secondary batteries) A lithium-ion secondary battery was fabricated in the same manner as in Example 3, except that the positive and negative electrodes obtained in Example 10 were used.

[0146] <Evaluation of adhesion of electrode laminates for energy storage devices> Each of the positive electrode and negative electrode laminates in the above examples was cut into strips measuring 2 cm wide x 10 cm long, and fixed with the electrode mixture coating surface facing upwards. Cellophane tape was attached to the electrode mixture coating surface, and the strength (N / cm) when the tape was peeled off at a speed of 10 mm / min in a 90° direction was measured five times, and the average value was taken as the peel strength. The larger this value, the better the adhesion (binding) by the primer layer. In other words, the adhesion between the electrode mixture, which is bound by the primer layer, and the current collector is excellent. The results are shown in Tables 1 and 2.

[0147] <Evaluation of Charge / Discharge Cycle Characteristics of Lithium-ion Secondary Batteries> For each lithium-ion secondary battery manufactured in the example, a charging cycle was performed at 25°C, charging to 4.3V (voltage represents voltage relative to lithium) with a constant current equivalent to 0.2C, then charging to 0.02C at the upper limit charging voltage, and finally discharging to 3V with a constant current equivalent to 0.2C. The capacity retention rate (in %) of the discharge capacity at 100 cycles relative to the discharge capacity at 1 cycle was calculated and used as an indicator of the battery's charge-discharge characteristics. A higher capacity retention rate indicates better performance. Note that 1C represents the current value required to discharge the battery's standard capacity in one hour, while 0.5C represents half that current value. The results are shown in Tables 1 and 2.

[0148] <Evaluation of discharge rate characteristics of lithium-ion secondary batteries> Using the lithium-ion secondary batteries manufactured in each example, they were charged at 25°C with a constant current equivalent to 0.2C up to 4.3V (voltage represents voltage relative to lithium), and then charged further until the current value reached 0.02C at the upper limit charging voltage. Next, they were discharged to 3V with a constant current equivalent to 0.2C, then charged in the same manner as above, and finally discharged to 3V with a constant current equivalent to 3C to evaluate the discharge rate characteristics. The retention rate of the discharge capacity after 3C discharge (3C discharge capacity), with the discharge capacity after 0.2C discharge (0.2C discharge capacity) set to 100%, was calculated based on the following formula and was defined as the initial discharge capacity ratio. A high initial discharge capacity ratio means that the resistance within the electrodes is low and excellent. Discharge capacity ratio (%)=(3C discharge capacity / 0.2C discharge capacity)×100 The results are shown in Tables 1 and 2.

[0149] [Table 1]

[0150] [Table 2]

[0151] As shown in Tables 1 and 2, the positive and negative electrode laminates of Examples 1-8, which contained copolymer A as a primer, all showed good adhesion. Furthermore, the lithium-ion secondary batteries obtained in Examples 1-8 exhibited good charge-discharge cycle characteristics and discharge rate characteristics. In contrast, the positive and negative electrode stacks in Example 9, which used a polymer other than copolymer A as a primer, exhibited poor adhesion. Furthermore, the lithium-ion secondary battery obtained in Example 9 had poor charge-discharge cycle characteristics and discharge rate characteristics. Similarly, although the positive and negative electrode stacks in Example 10 exhibited good adhesion, the lithium-ion secondary battery obtained in Example 10 also had poor charge-discharge cycle characteristics and discharge rate characteristics. Furthermore, the entire contents of the specification, claims, and abstract of Japanese Patent Application No. 2021-050217, filed on March 24, 2021, are incorporated herein by reference as disclosure of the present invention.

Claims

1. A primer for an electrode in a power storage device, for forming a primer layer provided between a current collector and an electrode active material layer, A primer for an electrode in an energy storage device, comprising a fluorine-containing copolymer having units based on tetrafluoroethylene and units based on ethylene, hexafluoropropylene, or perfluoro(alkyl vinyl ether), substantially free of units based on vinylidene fluoride, and having adhesive functional groups that can react with hydroxyl groups or form hydrogen bonds.

2. The primer according to claim 1, wherein the melting point of the fluorine-containing copolymer is 150°C or higher.

3. The primer according to claim 1 or 2, wherein the fluorine-containing copolymer has one or more adhesive functional groups selected from the group consisting of carbonyl-containing groups and hydroxyl groups.

4. The primer according to claim 3, wherein the fluorine-containing copolymer has at least one carbonyl-containing group selected from the group consisting of a group having a carbonyl group between carbon atoms of a hydrocarbon group, a carbonate group, a carboxyl group, a haloformyl group, an alkoxycarbonyl group, and an acid anhydride group as the adhesive functional group.

5. The primer according to any one of claims 1 to 4, wherein the fluorine-containing copolymer includes units based on ethylene.

6. Furthermore, the primer according to any one of claims 1 to 5, further containing a conductive material.

7. A composition for forming a primer layer, comprising a primer for an energy storage device electrode according to any one of claims 1 to 6 and a liquid medium.

8. The composition according to claim 7, wherein the liquid medium is one or more selected from the group consisting of aqueous media, aliphatic compounds, aromatic hydrocarbons, alcohols, ethers, esters, ketones, nitrogen-containing compounds, sulfur-containing compounds, and fluorine-containing compounds.

9. The composition according to claim 7, wherein the liquid medium is one or more selected from the group consisting of an aqueous medium, N-methylpyrrolidone, N,N-dimethylacetamide, and an aliphatic hydrocarbon compound having 6 to 10 carbon atoms and having one carbonyl group.

10. An electrode for an energy storage device having a current collector and an electrode active material layer formed on the current collector, An electrode for an energy storage device, having a primer layer between the current collector and the electrode active material layer, the primer for an energy storage device electrode described in any one of claims 1 to 6.

11. An electrode for an energy storage device having a current collector and an electrode active material layer formed on the current collector, An electrode for an energy storage device, having a primer layer formed from a primer layer forming composition according to any one of claims 7 to 9 between the current collector and the electrode active material layer.

12. An electrode for an energy storage device having a current collector and an electrode active material layer formed on the current collector, An electrode for an energy storage device, having a primer layer formed from the powder of the primer for energy storage device electrodes described in any one of claims 1 to 6 between the current collector and the electrode active material layer.

13. A secondary battery comprising an electrode and electrolyte for an energy storage device as described in any one of claims 10 to 12.

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