WO2018101308A1 - Électrode pour dispositif de stockage d'énergie, et dispositif de stockage d'énergie - Google Patents
Électrode pour dispositif de stockage d'énergie, et dispositif de stockage d'énergie Download PDFInfo
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- WO2018101308A1 WO2018101308A1 PCT/JP2017/042755 JP2017042755W WO2018101308A1 WO 2018101308 A1 WO2018101308 A1 WO 2018101308A1 JP 2017042755 W JP2017042755 W JP 2017042755W WO 2018101308 A1 WO2018101308 A1 WO 2018101308A1
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- 0 Cc1c(C)c(*)c(*)c(*)c1* Chemical compound Cc1c(C)c(*)c(*)c(*)c1* 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/06—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Definitions
- the present invention relates to an electrode for an energy storage device and an energy storage device.
- a lithium ion secondary battery is a secondary battery that is currently being most vigorously developed due to its high energy density, high voltage, and lack of a memory effect during charging and discharging.
- electric vehicles has been actively promoted due to recent efforts to deal with environmental problems, and higher performance has been demanded for secondary batteries as a power source.
- a positive electrode and a negative electrode that can occlude and release lithium, and a separator interposed therebetween are accommodated in a container, and an electrolyte solution (in the case of a lithium ion polymer secondary battery, liquid electrolysis is included). It has a structure filled with a gel or an all-solid electrolyte instead of a liquid.
- an active material capable of inserting and extracting lithium a conductive material mainly composed of a carbon material, and a composition containing a polymer binder are generally applied on a current collector such as a copper foil or an aluminum foil. It is manufactured by doing.
- This binder is used to bond the active material and the conductive material, and further to the metal foil, and is a fluorine-based resin soluble in N-methyl-2-pyrrolidone (NMP) such as polyvinylidene fluoride (PVdF), Aqueous dispersions of olefin polymers are commercially available.
- NMP N-methyl-2-pyrrolidone
- PVdF polyvinylidene fluoride
- the active material generally has low conductivity, and the conductivity of the electrodes such as the positive electrode and the negative electrode is mainly borne by the conductive material contained in the electrode.
- the conductivity of the electrodes such as the positive electrode and the negative electrode is mainly borne by the conductive material contained in the electrode.
- the proportion of the active material in the electrode is reduced, and the current flowing through the electrode flows through a part of the electrode. Since the active material and the conductive material are greatly different in weight, shape, size, specific gravity and the like, the electrodes are likely to be non-uniform, and the current flow tends to be non-uniform.
- Non-Patent Documents 1 and 2 are examples of evaluating the two-dimensional non-uniformity of charge / discharge of such an electrode, but the charge / discharge of the electrode is extremely non-uniform because the conductivity of the electrode is low. It has been shown. Such non-uniformity indicates that the electrode is easily charged and discharged locally, and is considered to cause deterioration of the battery. In order to improve such non-uniformity, it is necessary to increase the amount of the conductive additive added. However, as described above, since the ratio of the active material is decreased as a result, the capacity of the battery is decreased. There was a problem.
- This invention is made
- the present inventors have a conductive undercoat layer between the current collector substrate and the active material layer.
- an electrode that exhibits a predetermined X-ray absorption distribution when an X-ray absorption fine structure (XAFS) analysis is performed an energy storage device that can be charged and discharged uniformly is obtained.
- XAFS X-ray absorption fine structure
- the present invention provides the following electrode for energy storage device and energy storage device.
- An electrode for an energy storage device comprising: a current collecting substrate; an undercoat layer formed on at least one surface of the current collecting substrate; and an active material layer formed on the undercoat layer, After activating the energy storage device produced using the electrode, the device was discharged from a fully charged state to a discharge depth of 20%.
- a two-dimensional distribution of K absorption edge energy of metal atoms other than lithium contained in the active material in the electrode is measured by X-ray absorption fine structure analysis with a resolution of 10 to 50 ⁇ m square;
- the electrode for an energy storage device 3, wherein the active material is lithium iron phosphate. 5).
- the electrode for an energy storage device according to 7, wherein the carbon nanotube dispersant is a triarylamine hyperbranched polymer or a vinyl polymer containing an oxazoline group in a side chain.
- 10. The electrode for an energy storage device according to any one of 1 to 9, wherein the current collecting substrate is an aluminum foil or a copper foil. 11.
- An energy storage device comprising an electrode for an energy storage device according to any one of 11.1 to 10.
- an energy storage device that can be charged and discharged uniformly is obtained.
- the electrode for energy storage devices of this invention is equipped with a current collection board
- the electrode for energy storage device of the present invention is discharged from a fully charged state to a discharge depth of 20% after activation of the energy storage device manufactured using the electrode, and is included in the active material in the electrode of the device.
- the two-dimensional distribution of the K absorption edge energy of metal atoms other than lithium is measured by XAFS analysis with a resolution of 10 to 50 ⁇ m square, the K absorption edge energy in the fully charged state is A, and the K absorption edge energy in the fully discharged state is B.
- the half width of the histogram obtained as follows is
- activation means that complete charge / discharge is repeated for 1 to 5 cycles at 0.1 to 0.5 C.
- the device When the device is activated and discharged from a fully charged state to a discharge depth of 20%, it is preferable to discharge at 0.5 to 50 C, more preferably 0.5 to 10 C, and more preferably 0.5 to 1 C. It is even more preferable to discharge at.
- the charging is preferably performed at 0.01 to 10C, and more preferably at 0.1 to 0.5C.
- the half width of the obtained histogram is preferably
- the lower limit of the full width at half maximum is not particularly limited, but is usually a value greater than zero.
- the full width at half maximum is the same as the sample of the device electrode (hereinafter referred to as the first cycle sample) when the device is not charged / discharged after activation and the device is fully charged and then discharged to a discharge depth of 20%. It is preferable that it is a value measured as. If the half width of the sample in the first cycle is within the above range, charging and discharging can be performed uniformly. Therefore, even if the charging and discharging cycle is repeated, the electrode is not easily deteriorated, and a device having a long life can be obtained.
- substrate can use what was conventionally used as a current collection board
- thin films of copper, aluminum, nickel, gold, silver and alloys thereof, carbon materials, metal oxides, conductive polymers, etc. can be used, but electrode structures are applied by applying welding such as ultrasonic welding.
- the thickness of the current collector substrate is not particularly limited, but is preferably 1 to 100 ⁇ m in the present invention.
- the undercoat layer preferably contains a conductive material.
- the conductive material include carbon nanotube (CNT), carbon black, ketjen black, acetylene black, carbon whisker, carbon fiber, natural graphite, artificial graphite, titanium oxide, ITO, ruthenium oxide, aluminum, nickel and the like. Among these, CNT is preferable from the viewpoint of forming a uniform thin film.
- CNTs are generally produced by arc discharge, chemical vapor deposition (CVD), laser ablation, etc., but the CNTs used in the present invention may be obtained by any method. .
- a single-walled CNT in which a single carbon film (graphene sheet) is wound in a cylindrical shape
- DWCNT double-walled CNT
- MWCNT multi-layer CNTs
- SWCNT, DWCNT, and MWCNT can be used alone or in combination. From the viewpoint of cost, multilayer CNT is most advantageous.
- SWNT series [made by Meijo Nanocarbon Co., Ltd .: trade name]
- VGCF series made by Showa Denko KK: trade name]
- FloTube series made by CNano Technology Co., Ltd .: trade name]
- AMC Ube Industries, Ltd.]
- Manufactured trade name]
- NANOCYL NC7000 series [produced by Nanocyl SA: trade name]
- Baytubes produced by Bayer: trade name]
- GRAPHISTRENGTH produced by Arkema: trade name]
- MWNT7 made by Hodogaya Chemical Co., Ltd.): Product name
- Hyperion CNT manufactured by Hypeprion Catalysis International: trade name]
- the undercoat layer is preferably produced using a conductive material-containing composition (dispersion) containing the conductive material described above and a solvent.
- the solvent is not particularly limited as long as it is conventionally used for the preparation of a conductive material-containing composition such as CNT.
- a conductive material-containing composition such as CNT.
- water tetrahydrofuran (THF), diethyl ether, 1,2-dimethoxyethane (DME), etc.
- Ethers halogenated hydrocarbons such as methylene chloride, chloroform, 1,2-dichloroethane; N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone ( Amides such as NMP); Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; Alcohols such as methanol, ethanol, isopropanol and n-propanol; Aliphatic hydrocarbons such as n-heptane, n-hexane and cyclohexane Benzene, toluene, xylene, ethyl Examples include aromatic hydrocarbons such as benzene; glycol ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether; organic solvents such as
- solvent can be used individually by 1 type or in mixture of 2 or more types.
- water, NMP, DMF, THF, methanol, and isopropanol are preferable because the ratio of isolated dispersion of CNT can be improved.
- These solvent can be used individually by 1 type or in mixture of 2 or more types.
- the conductive material-containing composition may contain a matrix polymer as necessary.
- Matrix polymers include polyvinylidene fluoride (PVdF), polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer (P (VDF-HFP)), fluoride Fluorine-based resins such as vinylidene-chlorotrifluoroethylene copolymer (P (VDF-CTFE)), polyvinylpyrrolidone, ethylene-propylene-diene terpolymer, polyethylene (PE), polypropylene (PP), ethylene- Polyolefin resins such as vinyl acetate copolymer (EVA) and EEA (ethylene-ethyl acrylate copolymer); polystyrene (PS), high impact polystyrene (HIPS), acrylonitrile-styrene
- the matrix polymer can also be obtained as a commercial product.
- Aron A-10H polyacrylic acid, manufactured by Toagosei Co., Ltd., solid content concentration 26 mass%, aqueous solution
- Aron A-30 polyacrylic acid
- Ammonium manufactured by Toagosei Co., Ltd., solid concentration 32% by mass, aqueous solution
- sodium polyacrylate manufactured by Wako Pure Chemical Industries, Ltd., degree of polymerization 2,700-7,500
- sodium carboxymethylcellulose (Wako Pure) Yakuhin Kogyo Co., Ltd.), sodium alginate (manufactured by Kanto Chemical Co., Ltd., deer grade 1)
- Metroles registered trademark
- SH series hydroxypropylmethylcellulose, manufactured by Shin-Etsu Chemical Co., Ltd.
- Metroses SE series hydroxyethyl) Methyl cellulose, manufactured by Shin-Etsu Chemical Co., Ltd.
- JC-25 completely saponified poly
- the content of the matrix polymer is not particularly limited, but is preferably about 0.0001 to 99% by mass, more preferably about 0.001 to 90% by mass in the composition.
- the conductive material-containing composition may contain a dispersant in order to improve the dispersibility of the conductive material in the composition.
- a dispersing agent for example, carboxymethylcellulose (CMC), polyvinylpyrrolidone (PVP), an acrylic resin emulsion, a water-soluble acrylic polymer, a styrene emulsion, silicon
- Ar 1 to Ar 3 each independently represents any divalent organic group represented by the formulas (3) to (7).
- R 1 to R 38 each independently have a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms which may have a branched structure, or a branched structure. And an optionally substituted alkoxy group having 1 to 5 carbon atoms, a carboxyl group, a sulfo group, a phosphoric acid group, a phosphonic acid group or a salt thereof.
- examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
- alkyl group having 1 to 5 carbon atoms which may have a branched structure include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n -Pentyl group and the like.
- alkoxy group having 1 to 5 carbon atoms which may have a branched structure include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, and n-pentyloxy group.
- alkali metal salts such as sodium and potassium
- Group 2 metal salts such as magnesium and calcium
- ammonium salts propylamine, dimethylamine, triethylamine, ethylenediamine, etc.
- Z 1 and Z 2 are each independently a hydrogen atom, an alkyl group having 1 to 5 carbon atoms which may have a branched structure, or formulas (8) to (11 ) Represents any monovalent organic group. However, Z 1 and Z 2 do not simultaneously become the alkyl group.
- R 39 to R 62 each independently have a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms which may have a branched structure, or a branched structure.
- a haloalkyl group having 1 to 5 carbon atoms, a phenyl group, —OR 63 , —COR 63 , —NR 63 R 64 , or —COOR 65 (wherein R 63 and R 64 are each independently a hydrogen atom, alkyl group having 1 carbon atoms which may 5 have a branched structure, carbon atoms 1 may have a branched structure 1-5 haloalkyl group, or a phenyl group, R 65 is An alkyl group having 1 to 5 carbon atoms which may have a branched structure, a haloalkyl group having 1 to 5 carbon atoms which may have a branched structure, or a phenyl group), or a carb
- the haloalkyl group having 1 to 5 carbon atoms which may have a branched structure includes a difluoromethyl group, a trifluoromethyl group, a bromodifluoromethyl group, a 2-chloroethyl group, a 2-bromoethyl group, and 1,1.
- alkyl group having 1 to 5 carbon atoms which may have a halogen atom or a branched structure include the same groups as those exemplified in the formulas (2) to (7).
- Z 1 and Z 2 are each independently preferably a hydrogen atom, a 2- or 3-thienyl group, or a group represented by the formula (8), and particularly any one of Z 1 and Z 2 Is more preferably a hydrogen atom, the other being a hydrogen atom, a 2- or 3-thienyl group, a group represented by the formula (8), particularly those in which R 41 is a phenyl group, or R 41 is a methoxy group.
- R 41 is a phenyl group
- an acidic group may be introduced onto the phenyl group when a method for introducing an acidic group after polymer production is used in the acidic group introduction method described later.
- alkyl group having 1 to 5 carbon atoms which may have a branched structure include those described above.
- the hyperbranched polymer has a carboxyl group in at least one aromatic ring of the repeating unit represented by the formula (1) or (2), Those having at least one acidic group selected from a sulfo group, a phosphoric acid group, a phosphonic acid group, and salts thereof are preferred, and those having a sulfo group or a salt thereof are more preferred.
- the hyperbranched polymer having a repeating unit represented by the formula (1) is, for example, a triarylamine compound represented by the following formula (A) and, for example, the following formula (B) as shown in the following scheme 1. It is obtained by condensation polymerization of an aldehyde compound and / or a ketone compound as shown in the presence of an acid catalyst. (In the formula, Ar 1 to Ar 3 , Z 1 and Z 2 are the same as described above.)
- the hyperbranched polymer having a repeating unit represented by the formula (2) includes a triarylamine compound represented by the formula (A) and an aldehyde compound such as phthalate such as terephthalaldehyde. It can be obtained by condensation polymerization of a bifunctional compound represented by the following formula (C) such as aldehydes in the presence of an acid catalyst.
- a triarylamine compound represented by the formula (A) and an aldehyde compound such as phthalate such as terephthalaldehyde.
- a bifunctional compound represented by the following formula (C) such as aldehydes in the presence of an acid catalyst.
- an aldehyde compound and / or a ketone compound can be used at a ratio of 0.1 to 10 equivalents with respect to 1 equivalent of the aryl group of the triarylamine compound.
- the acid catalyst examples include mineral acids such as sulfuric acid, phosphoric acid and perchloric acid; organic sulfonic acids such as p-toluenesulfonic acid and p-toluenesulfonic acid monohydrate; carboxylic acids such as formic acid and oxalic acid. Etc. can be used.
- the amount of the acid catalyst to be used is variously selected depending on the kind thereof, but is usually preferably 0.001 to 10,000 parts by mass, more preferably 0.01 to 1,000 parts per 100 parts by mass of the triarylamines. Part by mass, more preferably 0.1 to 100 parts by mass.
- aldehyde compound examples include formaldehyde, paraformaldehyde, acetaldehyde, propylaldehyde, butyraldehyde, isobutyraldehyde, valeraldehyde, capronaldehyde, 2-methylbutyraldehyde, hexylaldehyde, undecylaldehyde, 7-methoxy-3,7-dimethyl.
- Saturated aliphatic aldehydes such as octyl aldehyde, cyclohexane carboxaldehyde, 3-methyl-2-butyraldehyde, glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, adipine aldehyde; unsaturated aliphatic aldehydes such as acrolein and methacrolein Heterocyclic aldehydes such as furfural, pyridine aldehyde, thiophene aldehyde; benzaldehyde, tolylaldehyde Hydride, trifluoromethylbenzaldehyde, phenylbenzaldehyde, salicylaldehyde, anisaldehyde, acetoxybenzaldehyde, terephthalaldehyde, acetylbenzaldehyde, formylbenzoic acid,
- the ketone compounds are alkyl aryl ketones and diaryl ketones, and examples thereof include acetophenone, propiophenone, diphenyl ketone, phenyl naphthyl ketone, dinaphthyl ketone, phenyl tolyl ketone, and ditolyl ketone.
- the condensation reaction can be performed without a solvent, but is usually performed using a solvent. Any solvent that does not inhibit the reaction can be used. Examples thereof include cyclic ethers such as tetrahydrofuran and 1,4-dioxane; N, N-dimethylformamide (DMF), N, N-dimethylacetamide ( DMAc), amides such as N-methyl-2-pyrrolidone (NMP); ketones such as methyl isobutyl ketone and cyclohexanone; halogenated hydrocarbons such as methylene chloride, chloroform, 1,2-dichloroethane and chlorobenzene; benzene, And aromatic hydrocarbons such as toluene and xylene. Of these, cyclic ethers are particularly preferable. These solvent can be used individually by 1 type or in mixture of 2 or more types.
- the acid catalyst used is a liquid such as formic acid, for example, the acid catalyst can also serve as a solvent.
- the reaction temperature during the condensation is usually 40 to 200 ° C.
- the reaction time is variously selected depending on the reaction temperature, but is usually about 30 minutes to 50 hours.
- the obtained hyperbranched polymer may be introduced by a method of treating with a reagent capable of introducing an acidic group on the aromatic ring, but the latter method may be used in consideration of the ease of production. preferable.
- the method for introducing the acidic group onto the aromatic ring is not particularly limited, and may be appropriately selected from conventionally known various methods according to the type of the acidic group. For example, when a sulfo group is introduced, a technique of sulfonation using an excessive amount of sulfuric acid can be used.
- the average molecular weight of the hyperbranched polymer is not particularly limited, but the weight average molecular weight (Mw) is preferably 1,000 to 2,000,000, more preferably 2,000 to 1,000,000. In the present invention, Mw is a value measured by gel permeation chromatography (in terms of polystyrene).
- hyperbranched polymer examples include, but are not limited to, those represented by the following formula.
- oxazoline polymer an oxazoline monomer having a polymerizable carbon-carbon double bond-containing group at the 2-position as represented by the formula (13):
- a polymer having a repeating unit bonded to a polymer main chain or a spacer group at the 2-position of the oxazoline ring, which is obtained by radical polymerization of is preferably used.
- X represents a polymerizable carbon-carbon double bond-containing group
- R 100 to R 103 each independently represent a hydrogen atom, a halogen atom, or a carbon number that may have a branched structure.
- An alkyl group having 1 to 5 carbon atoms, an aryl group having 6 to 20 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms is represented.
- the polymerizable carbon-carbon double bond-containing group is not particularly limited as long as it contains a polymerizable carbon-carbon double bond, but is preferably a chain hydrocarbon group containing a polymerizable carbon-carbon double bond,
- alkenyl groups having 2 to 8 carbon atoms such as vinyl group, allyl group, isopropenyl group and the like are preferable.
- halogen atom and the alkyl group having 1 to 5 carbon atoms which may have a branched structure include those described above.
- aryl group having 6 to 20 carbon atoms include phenyl group, xylyl group, tolyl group, biphenyl group, naphthyl group and the like.
- aralkyl group having 7 to 20 carbon atoms examples include benzyl group, phenylethyl group, phenylcyclohexyl group and the like.
- oxazoline monomer represented by the formula (13) examples include 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, 2-vinyl-4-ethyl-2-oxazoline, 2-vinyl Vinyl-4-propyl-2-oxazoline, 2-vinyl-4-butyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-vinyl-5-ethyl-2-oxazoline, 2-vinyl- 5-propyl-2-oxazoline, 2-vinyl-5-butyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-4-ethyl -2-oxazoline, 2-isopropenyl-4-propyl-2-oxazoline, 2-isopropenyl-4-butyl-2-oxazoly 2-isopropenyl-5-methyl
- the oxazoline polymer is preferably water-soluble.
- a water-soluble oxazoline polymer may be a homopolymer of the oxazoline monomer represented by the formula (13), but has a (meth) having a hydrophilic functional group with the oxazoline monomer in order to further improve the solubility in water. It is preferable that it is obtained by radical polymerization of at least two monomers with an acrylate monomer.
- the (meth) acrylic monomer having a hydrophilic functional group examples include (meth) acrylic acid, 2-hydroxyethyl acrylate, methoxypolyethylene glycol acrylate, monoesterified product of acrylic acid and polyethylene glycol, acrylic acid 2-aminoethyl and its salt, 2-hydroxyethyl methacrylate, methoxypolyethylene glycol methacrylate, monoesterified product of methacrylic acid and polyethylene glycol, 2-aminoethyl methacrylate and its salt, sodium (meth) acrylate, Examples include ammonium (meth) acrylate, (meth) acrylonitrile, (meth) acrylamide, N-methylol (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, sodium styrenesulfonate, and the like. These may be used alone or in combination of two or more. Among these, methoxypolyethylene glycol (meth) acrylate and mono
- other monomers other than the oxazoline monomer and the (meth) acrylic monomer having a hydrophilic functional group can be used in combination within a range that does not adversely affect the conductive material dispersibility of the oxazoline polymer.
- specific examples of other monomers include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, (meth) acrylic.
- (Meth) acrylic acid ester monomers such as perfluoroethyl acid and phenyl (meth) acrylate; ⁇ -olefin monomers such as ethylene, propylene, butene and pentene; haloolefins such as vinyl chloride, vinylidene chloride and vinyl fluoride Monomers; Styrene monomers such as styrene and ⁇ -methylstyrene; Vinyl ester monomers such as vinyl acetate and vinyl propionate; Vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether. These may be used alone or in combination of two or more.
- the content of the oxazoline monomer is preferably 10% by mass or more, more preferably 20% by mass or more from the viewpoint that the conductive material dispersibility of the obtained oxazoline polymer is further increased. Preferably, 30% by mass or more is even more preferable.
- the upper limit of the content rate of the oxazoline monomer in a monomer component is 100 mass%, and the homopolymer of an oxazoline monomer is obtained in this case.
- the content of the (meth) acrylic monomer having a hydrophilic functional group in the monomer component is preferably 10% by mass or more, more preferably 20% by mass or more from the viewpoint of further improving the water solubility of the obtained oxazoline polymer. 30% by mass or more is even more preferable.
- the content of other monomers in the monomer component is in a range that does not affect the conductive material dispersibility of the obtained oxazoline polymer. What is necessary is just to set suitably in the range of 5-95 mass%, Preferably it is 10-90 mass%.
- the average molecular weight of the oxazoline polymer is not particularly limited, but Mw is preferably 1,000 to 2,000,000, more preferably 2,000 to 1,000,000.
- the oxazoline polymer that can be used in the present invention can be synthesized by the conventional radical polymerization of the above-mentioned monomers, but can also be obtained as a commercial product, and as such a commercial product, for example, Epocross (registered trademark) ) WS-300 (manufactured by Nippon Shokubai Co., Ltd., solid concentration 10 mass%, aqueous solution), Epocross WS-700 (manufactured by Nippon Shokubai Co., Ltd., solid content concentration 25 mass%, aqueous solution), Epocross WS-500 (( Manufactured by Nippon Shokubai Co., Ltd., solid content: 39% by mass, water / 1-methoxy-2-propanol solution), Poly (2-ethyl-2-oxazoline) (Aldrich), Poly (2-ethyl-2-oxazoline) ) (Manufactured by Alfa Aesar), Poly (2-ethyl-2-
- the mixing ratio of the conductive material and the dispersant in the conductive material-containing composition can be about 1,000: 1 to 1: 100 in terms of mass ratio.
- the concentration of the dispersing agent is not particularly limited as long as the conductive material can be dispersed in the solvent, but is preferably about 0.001 to 30% by mass, and about 0.002 to 20% by mass in the composition. More preferably.
- the concentration of the conductive material changes in the weight of the target undercoat layer and the required mechanical, electrical, thermal characteristics, etc., and at least a part of the conductive material is isolated and dispersed, although it is optional as long as the undercoat layer can be produced with an appropriate basis weight, it is preferably about 0.0001 to 30% by mass in the composition, more preferably about 0.001 to 20% by mass, More preferably, it is about 0.001 to 10% by mass.
- the conductive material-containing composition may contain a crosslinking agent that causes a crosslinking reaction with the dispersant to be used, or a crosslinking agent that self-crosslinks. These crosslinking agents are preferably dissolved in the solvent used.
- crosslinking agent for the triarylamine-based hyperbranched polymer examples include melamine-based, substituted urea-based, and these polymer-based crosslinking agents. These crosslinking agents can be used alone or in combination of two or more. Preferably, it is a cross-linking agent having at least two cross-linking substituents, specifically, CYMEL (registered trademark), methoxymethylated glycoluril, butoxymethylated glycoluril, methylolated glycoluril, methoxymethyl.
- CYMEL registered trademark
- the cross-linking agent of the oxazoline polymer for example, a compound having two or more functional groups having reactivity with an oxazoline group such as a carboxyl group, a hydroxy group, a thiol group, an amino group, a sulfinic acid group, and an epoxy group is particularly preferable.
- an oxazoline group such as a carboxyl group, a hydroxy group, a thiol group, an amino group, a sulfinic acid group, and an epoxy group
- the compound which has 2 or more of carboxyl groups is preferable.
- a compound having a functional group that causes a crosslinking reaction by heating during the formation of a thin film or in the presence of an acid catalyst such as a sodium salt, potassium salt, lithium salt, or ammonium salt of a carboxylic acid is also crosslinked. It can be used as an agent.
- compounds that cause a crosslinking reaction with an oxazoline group include metal salts of synthetic polymers such as polyacrylic acid and copolymers thereof and natural polymers such as carboxymethylcellulose and alginic acid that exhibit crosslinking reactivity in the presence of an acid catalyst.
- metal salts of synthetic polymers such as polyacrylic acid and copolymers thereof and natural polymers such as carboxymethylcellulose and alginic acid that exhibit crosslinking reactivity in the presence of an acid catalyst.
- examples thereof include ammonium salts of the above synthetic polymers and natural polymers that exhibit crosslinking reactivity upon heating.
- sodium polyacrylate, lithium polyacrylate, ammonium polyacrylate, sodium carboxymethylcellulose, lithium carboxymethylcellulose, carboxymethylcellulose ammonium and the like that exhibit crosslinking reactivity in the presence of an acid catalyst or under heating conditions are preferred.
- Such a compound that causes a crosslinking reaction with an oxazoline group can also be obtained as a commercial product.
- a commercial product examples include sodium polyacrylate (manufactured by Wako Pure Chemical Industries, Ltd., degree of polymerization: 2, 700-7,500), sodium carboxymethylcellulose (manufactured by Wako Pure Chemical Industries, Ltd.), sodium alginate (manufactured by Kanto Chemical Co., Ltd., deer grade 1), Aron A-30 (polyammonium acrylate, Toagosei Co., Ltd.) ), Solid concentration 32% by mass, aqueous solution), DN-800H (carboxymethylcellulose ammonium, manufactured by Daicel Finechem Co., Ltd.), ammonium alginate (manufactured by Kimika Co., Ltd.), and the like.
- crosslinking agent examples include, for example, an aldehyde group for an hydroxy group, an epoxy group, a vinyl group, an isocyanate group or an alkoxy group, an aldehyde group for a carboxyl group, an amino group, an isocyanate group or an epoxy group, an isocyanate group or an aldehyde for an amino group.
- crosslinkable functional groups that react with each other in the same molecule, such as groups, hydroxy groups that react with the same crosslinkable functional groups (dehydration condensation), mercapto groups (disulfide bonds), ester groups (Claisen) (Condensation), silanol group (dehydration condensation), vinyl group, acryl group and the like.
- Specific examples of the crosslinking agent that self-crosslinks include at least one of a polyfunctional acrylate, a tetraalkoxysilane, a monomer having a blocked isocyanate group, a hydroxy group, a carboxylic acid, and an amino group that exhibit crosslinking reactivity in the presence of an acid catalyst.
- Such a self-crosslinking cross-linking agent can also be obtained as a commercial product, and as such a commercial product, for example, polyfunctional acrylate, A-9300 (ethoxylated isocyanuric acid triacrylate, Shin-Nakamura Chemical Co., Ltd. ( Co., Ltd.), A-GLY-9E (Ethoxylated glycerine triacrylate (EO9mol), Shin-Nakamura Chemical Co., Ltd.), A-TMMT (pentaerythritol tetraacrylate, Shin-Nakamura Chemical Co., Ltd.), etc.
- polyfunctional acrylate A-9300 (ethoxylated isocyanuric acid triacrylate, Shin-Nakamura Chemical Co., Ltd. ( Co., Ltd.), A-GLY-9E (Ethoxylated glycerine triacrylate (EO9mol), Shin-Nakamura Chemical Co., Ltd.), A-TMMT (pentaerythritol tetraacryl
- tetraalkoxysilane examples include tetramethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), tetraethoxysilane (manufactured by Toyoko Chemical Co., Ltd.), etc., and polymers having a blocked isocyanate group include Elastron series E-37, H-3, H38, BAP, NEW BAP-15, C-52, F-29, W-11P, MF-9, MF-25K (Daiichi Kogyo Seiyaku Co., Ltd.) and the like.
- the amount of these crosslinking agents to be added varies depending on the solvent used, the substrate used, the required viscosity, the required film shape, etc., but is 0.001 to 80% by mass with respect to the dispersant, preferably 0.00.
- the amount is from 01 to 50% by mass, more preferably from 0.05 to 40% by mass.
- These cross-linking agents may cause a cross-linking reaction due to self-condensation, but they cause a cross-linking reaction with the dispersant. If a cross-linkable substituent is present in the dispersant, the cross-linking reaction is caused by these cross-linkable substituents. Is promoted.
- p-toluenesulfonic acid as a catalyst for accelerating the crosslinking reaction, p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium p-toluenesulfonic acid, salicylic acid, sulfosalicylic acid, citric acid, benzoic acid, hydroxybenzoic acid, naphthalenecarboxylic acid And / or a thermal acid generator such as 2,4,4,6-tetrabromocyclohexadienone, benzoin tosylate, 2-nitrobenzyl tosylate, and organic sulfonic acid alkyl ester can be added. .
- the addition amount of the catalyst is 0.0001 to 20% by mass, preferably 0.0005 to 10% by mass, and more preferably 0.001 to 3% by mass with respect to the conductive material dispersant.
- the method for preparing the conductive material-containing composition is not particularly limited.
- a conductive material such as CNT and a solvent, and a dispersant, a matrix polymer, and a crosslinking agent used as necessary are mixed in any order. can do.
- this treatment can further improve the dispersion ratio of the conductive material such as CNT.
- the dispersion treatment include mechanical treatment, wet treatment using a ball mill, bead mill, jet mill, or the like, and ultrasonic treatment using a bath type or probe type sonicator. Of these, wet processing and ultrasonic processing using a jet mill are preferred.
- the time for the dispersion treatment is arbitrary, but is preferably about 1 minute to 10 hours, more preferably about 5 minutes to 5 hours. At this time, heat treatment may be performed as necessary.
- a crosslinking agent and / or matrix polymer you may add these, after preparing the mixture which consists of electrically conductive materials, such as a dispersing agent, CNT, and a solvent.
- the undercoat layer can be formed by applying the conductive material-containing composition to at least one surface of the current collecting substrate and drying it naturally or by heating. At this time, it is preferable to apply the conductive material-containing composition to the entire surface of the current collector substrate and form an undercoat layer on the entire surface of the current collector substrate.
- substrate is also called undercoat foil.
- the basis weight of the undercoat layer per one surface of the current collector substrate is set to 0 in order to efficiently join the undercoat foil and a metal tab described later by welding such as ultrasonic welding at the undercoat layer portion of the foil. .1g / m 2 or less, preferably 0.09 g / m 2 or less, and more preferably less than 0.05 g / m 2.
- the basis weight of the undercoat layer per surface of the current collecting substrate is preferably 0.001 g / m 2 or more, more preferably 0.005 g / m 2 or more, even more preferably 0.01 g / m 2 or more, further preferably 0.015 g / m 2 or more.
- the thickness of the undercoat layer is not particularly limited as long as the weight per unit area is satisfied. However, in consideration of reducing the welding efficiency and the internal resistance of the obtained device, 0.01 to 10 ⁇ m is preferable, and 0.02 to 5 ⁇ m. Is more preferable, and 0.03 to 1 ⁇ m is even more preferable.
- the basis weight of the undercoat layer in the present invention is the ratio of the mass (g) of the undercoat layer to the area (m 2 ) of the undercoat layer.
- the area is The area is only the undercoat layer and does not include the area of the current collector substrate exposed between the undercoat layers formed in a pattern.
- the mass of the undercoat layer for example, a test piece of an appropriate size was cut out from the undercoat foil, and its mass W 0 was measured. Thereafter, the undercoat layer was peeled off from the undercoat foil, and the undercoat layer was peeled off. The subsequent mass W 1 is measured and calculated from the difference (W 0 ⁇ W 1 ), or the mass W 2 of the current collecting substrate is measured in advance, and then the undercoat foil mass on which the undercoat layer is formed W 3 can be measured and calculated from the difference (W 3 ⁇ W 2 ).
- Examples of the method for peeling the undercoat layer include a method of immersing the undercoat layer in a solvent in which the undercoat layer is dissolved or swelled and wiping the undercoat layer with a cloth or the like.
- the basis weight can be adjusted by a known method. For example, when the undercoat layer is formed by coating, the solid content concentration of the coating liquid (conductive material-containing composition) for forming the undercoat layer, the number of coatings, the clearance of the coating liquid inlet of the coating machine, etc. It can be adjusted by changing To increase the weight per unit area, increase the solid content concentration, increase the number of coatings, or increase the clearance. When it is desired to reduce the basis weight, the solid content concentration is decreased, the number of coatings is decreased, or the clearance is decreased.
- the coating liquid conductive material-containing composition
- Examples of the method for applying the conductive material-containing composition include spin coating, dip coating, flow coating, ink jet, spray coating, bar coating, gravure coating, slit coating, roll coating, and flexographic printing. Method, transfer printing method, brush coating, blade coating method, air knife coating method and the like. Of these, the inkjet method, casting method, dip coating method, bar coating method, blade coating method, roll coating method, gravure coating method, flexographic printing method, and spray coating method are preferable from the viewpoint of work efficiency and the like.
- the temperature for heating and drying is arbitrary, but is preferably about 50 to 200 ° C, more preferably about 80 to 150 ° C.
- active material layer various active materials conventionally used for electrodes for energy storage devices can be used.
- a chalcogen compound capable of adsorbing / leaving lithium ions or a lithium ion-containing chalcogen compound, a polyanion compound, a simple substance of sulfur and a compound thereof may be used as a positive electrode active material. it can.
- Examples of the chalcogen compound that can adsorb and desorb lithium ions include FeS 2 , TiS 2 , MoS 2 , V 2 O 6 , V 6 O 13 , and MnO 2 .
- lithium ion-containing chalcogen compound examples include LiCoO 2 , LiMnO 2 , LiMn 2 O 4 , LiMo 2 O 4 , LiV 3 O 8 , LiNiO 2 , Li x Ni y M 1-y O 2 (where M is Co Represents at least one metal element selected from Mn, Ti, Cr, V, Al, Sn, Pb, and Zn, 0.05 ⁇ x ⁇ 1.10, 0.5 ⁇ y ⁇ 1.0) Etc.
- Examples of the polyanionic compound include lithium iron phosphate (LiFePO 4 ).
- Examples of the sulfur compound include Li 2 S and rubeanic acid.
- the negative electrode active material constituting the negative electrode at least one element selected from alkali metals, alkali alloys, and elements of Groups 4 to 15 of the periodic table that occlude / release lithium ions, oxides, sulfides, nitrides Or a carbon material capable of reversibly occluding and releasing lithium ions can be used.
- alkali metal examples include Li, Na, K, and the like
- alkali metal alloy examples include Li—Al, Li—Mg, Li—Al—Ni, Na—Hg, Na—Zn, and the like.
- Examples of the simple substance of at least one element selected from Group 4 to 15 elements of the periodic table that occlude and release lithium ions include silicon, tin, aluminum, zinc, and arsenic.
- examples of the oxide include tin silicon oxide (SnSiO 3 ), lithium bismuth oxide (Li 3 BiO 4 ), lithium zinc oxide (Li 2 ZnO 2 ), and lithium titanium oxide (Li 4 Ti 5 O 12 ). Can be mentioned.
- examples of the sulfide include lithium iron sulfide (Li x FeS 2 (0 ⁇ x ⁇ 3)) and lithium copper sulfide (Li x CuS (0 ⁇ x ⁇ 3)).
- Examples of the carbon material capable of reversibly occluding and releasing lithium ions include graphite, carbon black, coke, glassy carbon, carbon fiber, carbon nanotube, and a sintered body thereof.
- the thickness of the active material layer is preferably 10 to 500 ⁇ m, more preferably 10 to 300 ⁇ m, and even more preferably 20 to 100 ⁇ m in consideration of the balance between the capacity and resistance of the battery.
- the heavy atom means a metal atom heavier than scandium.
- what contains heavy atoms such as iron, nickel, lead, titanium, manganese, cobalt, tin, chromium, vanadium, zinc, ruthenium, is preferable.
- those containing iron atoms are preferred, and lithium iron phosphate is more preferred.
- the active material layer can be formed by applying the electrode slurry containing the active material, the binder polymer, and, if necessary, the solvent described above on the undercoat layer and naturally or by heating and drying.
- the formation part of the active material layer may be appropriately set according to the cell form of the device to be used, and may be all or part of the surface of the undercoat layer. Is used as an electrode structure joined by welding such as ultrasonic welding, it is preferable to form an active material layer by applying electrode slurry to a part of the surface of the undercoat layer in order to leave a weld. In particular, in a laminate cell application, it is preferable to form an active material layer by applying an electrode slurry to the remaining part of the undercoat layer other than the periphery.
- the binder polymer can be appropriately selected from known materials and used, for example, PVdF, polyvinylpyrrolidone, polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, P (VDF-HFP), P ( VDF-CTFE), polyvinyl alcohol, polyimide, ethylene-propylene-diene terpolymer, styrene-butadiene rubber, CMC, polyacrylic acid (PAA), polyaniline, and other conductive polymers.
- PVdF polyvinylpyrrolidone
- polytetrafluoroethylene polytetrafluoroethylene-hexafluoropropylene copolymer
- P (VDF-HFP) P
- VDF-CTFE VDF-CTFE
- polyvinyl alcohol polyimide
- ethylene-propylene-diene terpolymer ethylene-propylene-diene terpolymer
- the addition amount of the binder polymer is preferably 0.1 to 20 parts by mass, particularly 1 to 10 parts by mass with respect to 100 parts by mass of the active material.
- the solvent examples include the solvents exemplified in the conductive material-containing composition, and may be appropriately selected according to the type of the binder, but NMP is preferable in the case of a water-insoluble binder such as PVdF. In the case of a water-soluble binder such as PAA, water is preferable.
- the electrode slurry may contain a conductive additive.
- the conductive assistant include carbon black, ketjen black, acetylene black, carbon whisker, carbon fiber, natural graphite, artificial graphite, titanium oxide, ruthenium oxide, aluminum, nickel and the like.
- the temperature for drying by heating is arbitrary, but is preferably about 50 to 400 ° C, more preferably about 80 to 150 ° C.
- the electrode can be pressed as necessary.
- a generally adopted method can be used, but a die pressing method and a roll pressing method are particularly preferable.
- the press pressure in the roll press method is not particularly limited, but is preferably 0.2 to 3 ton / cm.
- the energy storage device of the present invention includes the above-described electrode for energy storage device, and more specifically, includes at least a pair of positive and negative electrodes, a separator interposed between these electrodes, and an electrolyte. And at least one of the positive and negative electrodes is composed of the above-described electrode for an energy storage device.
- Examples of the energy storage device of the present invention include various energy storage devices such as a lithium ion secondary battery, a hybrid capacitor, a lithium secondary battery, a nickel hydride battery, and a lead storage battery.
- this energy storage device is characterized by the use of the above-mentioned electrode for energy storage device as an electrode, other device constituent members such as separators and electrolytes may be appropriately selected from known materials and used. it can.
- the separator examples include a cellulose separator and a polyolefin separator.
- the electrolyte may be either liquid or solid, and may be either aqueous or non-aqueous.
- the electrode for an energy storage device of the present invention is practically sufficient even when applied to a device using a non-aqueous electrolyte. Performance can be demonstrated.
- non-aqueous electrolyte examples include a non-aqueous electrolyte obtained by dissolving an electrolyte salt in a non-aqueous organic solvent.
- electrolyte salts include lithium salts such as lithium tetrafluoroborate, lithium hexafluorophosphate, lithium perchlorate, and lithium trifluoromethanesulfonate; tetramethylammonium hexafluorophosphate, tetraethylammonium hexafluorophosphate, tetrapropylammonium Quaternary ammonium salts such as hexafluorophosphate, methyltriethylammonium hexafluorophosphate, tetraethylammonium tetrafluoroborate, tetraethylammonium perchlorate, lithium imides such as lithium bis (trifluoromethanesulfonyl) imide, lithium bis (fluo
- non-aqueous organic solvent examples include alkylene carbonates such as propylene carbonate, ethylene carbonate, and butylene carbonate; dialkyl carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; nitriles such as acetonitrile; and amides such as dimethylformamide. .
- the form of the energy storage device is not particularly limited, and it is possible to adopt various types of cells known in the art such as a cylindrical type, a flat wound rectangular type, a laminated square type, a coin type, a flat wound laminated type, and a laminated laminated type. it can.
- the above-described electrode for an energy storage device of the present invention may be used by punching it into a predetermined disk shape.
- a predetermined number of lithium foils punched into a predetermined shape are placed on a lid to which a coin cell washer and spacer are welded, and a separator of the same shape impregnated with an electrolyte is stacked thereon.
- the electrode for an energy storage device of the present invention can be overlaid with the active material layer down, and a case and a gasket can be placed thereon and sealed with a coin cell caulking machine.
- the electrode in which the active material layer is formed on a part of the surface of the undercoat layer has a metal in the portion (welded part) where the undercoat layer is formed and the active material layer is not formed.
- An electrode structure obtained by welding with a tab may be used.
- one or a plurality of electrodes constituting the electrode structure may be used, but generally a plurality of positive and negative electrodes are used. It is preferable that the plurality of electrodes for forming the positive electrode are alternately stacked one by one with the plurality of electrode plates for forming the negative electrode, and the separator described above is interposed between the positive electrode and the negative electrode. It is preferable to make it.
- the metal tab is welded at the welded portion of the outermost electrode of the plurality of electrodes, the metal tab is welded with the metal tab sandwiched between the welded portions of any two adjacent electrodes among the plurality of electrodes. Also good.
- the material of the metal tab is not particularly limited as long as it is generally used for energy storage devices, for example, metals such as nickel, aluminum, titanium, copper; stainless steel, nickel alloy, aluminum alloy, titanium alloy, Examples include alloys such as copper alloys. Among these, in consideration of welding efficiency, those including at least one metal selected from aluminum, copper and nickel are preferable.
- the shape of the metal tab is preferably a foil shape, and the thickness is preferably about 0.05 to 1 mm.
- the welding method a known method used for metal-to-metal welding can be used. Specific examples thereof include TIG welding, spot welding, laser welding, ultrasonic welding, and the like. Since the undercoat layer has a basis weight particularly suitable for ultrasonic welding, it is preferable to join the electrode and the metal tab by ultrasonic welding.
- a technique of ultrasonic welding for example, a plurality of electrodes are arranged between an anvil and a horn, a metal tab is arranged in a welded portion, and ultrasonic welding is applied to collect a plurality of electrodes.
- a technique of welding first and then welding a metal tab is exemplified.
- the metal tab and the electrode are welded at the welded portion, but also the plurality of electrodes are formed with an undercoat layer and no active material layer is formed.
- the parts will be ultrasonically welded together.
- the pressure, frequency, output, processing time, and the like during welding are not particularly limited, and may be set as appropriate in consideration of the material used, the basis weight of the undercoat layer, and the like.
- the electrode structure produced as described above is accommodated in a laminate pack, and after injecting the above-described electrolyte solution, heat sealing is performed to obtain a laminate cell.
- the energy storage device thus obtained has at least one electrode structure including a metal tab and one or a plurality of electrodes, and the electrode includes a current collector substrate and the current collector.
- the electrode includes a current collector substrate and the current collector.
- Rotating / revolving mixer (defoaming electrode slurry) Equipment: Shintaro Awatori Ryotaro ARE-310 (8)
- Roll press device (electrode compression) Equipment: Hosen Co., Ltd. ultra-compact desktop heat roll press HSR-60150H (9) Scanning electron microscope (SEM) Equipment: JEOL JSM-7400F
- This mixture was subjected to ultrasonic treatment at room temperature (approximately 25 ° C.) for 30 minutes using a probe-type ultrasonic irradiation device to obtain a black MWCNT-containing dispersion liquid in which MWCNT was uniformly dispersed without a precipitate.
- a probe-type ultrasonic irradiation device To 50 g of the obtained MWCNT-containing dispersion, 3.88 g of Aron A-10H (manufactured by Toagosei Co., Ltd., solid content concentration 25.8 mass%), which is an aqueous solution containing polyacrylic acid (PAA), and 2-propanol 46 .12 g was added and stirred to obtain an undercoat solution A.
- PAA polyacrylic acid
- the undercoat solution A is uniformly spread on an aluminum foil (thickness 15 ⁇ m) as a current collecting substrate with a wire bar coater (OSP30 manufactured by Matsuo Sangyo Co., Ltd., wet film thickness 30 ⁇ m), and then dried at 120 ° C. for 20 minutes to form an undercoat.
- a coat layer was formed to prepare an undercoat foil A. When the undercoat foil was torn and the cross section was observed by SEM, the thickness of the undercoat layer was about 250 nm.
- the slurry was mixed for 60 seconds at a peripheral speed of 20 m / sec using a thin film swirl type high-speed mixer, and further defoamed at 2,200 rpm for 30 seconds with a rotating / revolving mixer, so that an electrode slurry (solid content concentration 48) was obtained.
- Mass%, LFP: PVdF: AB 90: 8: 2 (mass ratio)).
- the obtained electrode slurry is uniformly spread on the undercoat foil A (wet film thickness 200 ⁇ m), it is dried at 80 ° C. for 30 minutes and then at 120 ° C. for 30 minutes to form an active material layer on the undercoat layer, Furthermore, an electrode having an active material layer thickness of 50 ⁇ m was produced by pressure bonding with a roll press.
- a separator (Selgard Co., Ltd., 2500) punched to a diameter of 16 mm, which was impregnated with (volume ratio), 1 mol / L of lithium hexafluorophosphate as an electrolyte, was stacked one by one. Further, the electrodes were stacked from the top with the surface coated with the active material facing down. Further, 0.2 mL of the electrolytic solution was dropped, and then the HS type test cell was sealed, and then allowed to stand for 24 hours to obtain a lithium ion secondary battery A for testing.
- Example 1 An electrode was produced in the same manner as in Example 1 except that a solid aluminum foil without an undercoat layer was used, and a test lithium ion secondary battery B was produced using the electrode.
- Example 1 three lithium ion secondary batteries were produced in the same manner as in Example 1 and Comparative Example 1, and 0.5C (the capacity of LFP was set to 170 mAh / g) using a charge / discharge measuring device.
- the battery was activated by charging and discharging for 5 cycles at a cutoff voltage of 4.50 to 2.00 V and room temperature. Subsequently, a full charge at 0.5C was performed for one cycle of complete discharge at 5C, and a sample that was further fully charged at 0.5C and discharged to a discharge depth of 20% at 5C was taken as a second cycle sample.
- a sample that was fully charged at 0.5C and fully discharged at 5C for 3 cycles, and further charged at 0.5C and discharged at 5C to a discharge depth of 20% was taken as a sample for the fourth cycle.
- a sample that was fully charged at 0.5 C and completely discharged at 5 C for 5 cycles, and further fully charged at 0.5 C and discharged to a discharge depth of 20% at 5 C was taken as a sample for the sixth cycle.
- the sample for imaging XAFS was produced similarly to the above.
- Imaging XAFS measurements were performed at the Ritsumeikan University SR Center BL-4.
- a two-dimensional detector for X-rays was used as a transmission intensity monitor in a transmission arrangement.
- Incident X-ray intensity was measured with an ion chamber.
- the spatial resolution was 26 ⁇ m.
- the area that can be observed by one measurement is 13 mm ⁇ 3 mm, and in order to grasp the reaction in the entire electrode having a diameter of 13 mm, three samples were measured for each sample.
- the measurement energy range is in the vicinity of the K absorption edge of iron (7,076 to 7,181 eV), the absorption spectrum is calculated with each element from the obtained transmission image of each energy, and the element of the detector corresponding to the position on the sample Each chemical state was determined.
- the K absorption edge energy of iron was used, and LiFePO 4 and FePO 4 were used as standard samples.
- the absorption edge energy of LiFePO 4 was 718.6 eV, and the absorption edge energy of FePO 4 was 713.6 eV.
- the absorption edge energy of FePO 4 corresponds to the K absorption edge energy in the fully charged state, and the absorption edge energy of LiFePO 4 corresponds to the K absorption edge energy in the fully discharged state.
- FIG. 1 shows an imaging XAFS image of the positive electrode after disassembly
- FIG. 2 shows a histogram of the absorption edge energy for all the measured regions
- Table 1 shows the half width of the histogram obtained from FIG.
- the histogram did not widen even after repeated cycles, whereas Comparative Example 1 In the lithium ion secondary battery using solid aluminum foil as the current collecting substrate manufactured in step 1, the histogram spreads.
- the half width of the histogram shown in Table 1 in the lithium ion secondary battery using the solid aluminum foil, the half width of the initial histogram is as large as 0.60 eV, and the half width is increased with each cycle.
- the half-value width of the initial histogram was as small as 0.56 eV, and the half-value width did not change greatly even when the cycle was repeated.
- the initial charge / discharge reaction is non-uniform, so repeating the cycle increases the non-uniformity and leads to deterioration of the battery.
- the initial charge / discharge reaction is uniform, so that the uniformity is maintained even when the cycle is repeated, and the battery has a long life.
- the full width at half maximum in the first cycle of the discharge from the fully charged state to the discharge depth of 20% is set to
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Abstract
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WO2023032702A1 (fr) * | 2021-09-03 | 2023-03-09 | ルビコン株式会社 | Dispositif de stockage d'énergie et son procédé de fabrication |
WO2024009988A1 (fr) * | 2022-07-04 | 2024-01-11 | 積水化学工業株式会社 | Électrode positive pour batteries secondaires à électrolyte non aqueux et batterie secondaire à électrolyte non aqueux, module de batterie et système de batterie l'utilisant, et procédé de production d'électrode positive pour batteries secondaires à électrolyte non aqueux |
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WO2014042080A1 (fr) * | 2012-09-14 | 2014-03-20 | 日産化学工業株式会社 | Collecteur de courant composite destiné à une électrode de dispositif de stockage d'énergie, et électrode |
WO2015029949A1 (fr) * | 2013-08-27 | 2015-03-05 | 日産化学工業株式会社 | Agent pour disperser un matériau carboné électroconducteur, et dispersion de matériau carboné électroconducteur |
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WO2014042080A1 (fr) * | 2012-09-14 | 2014-03-20 | 日産化学工業株式会社 | Collecteur de courant composite destiné à une électrode de dispositif de stockage d'énergie, et électrode |
WO2015029949A1 (fr) * | 2013-08-27 | 2015-03-05 | 日産化学工業株式会社 | Agent pour disperser un matériau carboné électroconducteur, et dispersion de matériau carboné électroconducteur |
Cited By (2)
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WO2023032702A1 (fr) * | 2021-09-03 | 2023-03-09 | ルビコン株式会社 | Dispositif de stockage d'énergie et son procédé de fabrication |
WO2024009988A1 (fr) * | 2022-07-04 | 2024-01-11 | 積水化学工業株式会社 | Électrode positive pour batteries secondaires à électrolyte non aqueux et batterie secondaire à électrolyte non aqueux, module de batterie et système de batterie l'utilisant, et procédé de production d'électrode positive pour batteries secondaires à électrolyte non aqueux |
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TW201834301A (zh) | 2018-09-16 |
JPWO2018101308A1 (ja) | 2019-10-24 |
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