JP2014042063A - Method for manufacturing electrode for electrochemical element, electrode for electrochemical element, and electrochemical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrode for an electrochemical element which has high coating efficiency, is stable, and has low internal resistance.SOLUTION: A method for manufacturing an electrode for an electrochemical element, in which electrode material comprising electrode active material, a binder, a conductive assistant, and electrification control resin are electrified and supplied to at least one face on a collector, thereby an electrode layer is formed; and the electrochemical element comprising the electrode for the electrochemical element obtained by the manufacturing method are provided. Preferably, an amount of surface electrification "C" (μ*C/g) of the electrification control resin is in a range of 10≤|C|≤600.

Description

  The present invention relates to a method for producing an electrode for an electrochemical element, an electrode for an electrochemical element obtained thereby, and an electrochemical element provided with this electrode. More specifically, a manufacturing method for manufacturing an electrode for an electrochemical element having a thin and uniform electrode thickness and capable of reducing internal resistance with high productivity, an electrode for an electrochemical element obtained thereby, and an electrochemical element provided with the electrode About.

  Lithium ion secondary batteries and electric double layer capacitors are expected to be applied as large power supplies such as distributed power supplies and hybrid vehicles due to environmental problems and resource problems of energy. However, in order to apply these electrochemical elements as a large power source, it is necessary to reduce internal resistance and energy loss during large current discharge.

  In order to reduce internal resistance, it is generally performed to make the electrode thickness thin and uniform, and it is required to manufacture a thin film electrode with high productivity.

  As an electrode manufacturing method, an electrode material containing an electrode active material, a binder, etc. is made into a slurry, and applied to a current collector and dried; the electrode material is kneaded and extended to a target thickness with a rolling roll. A method of pressure forming the electrode material as it is or in the form of composite particles. Among these, the method of pressure-molding the electrode material is preferable in terms of productivity, and various methods for supplying the electrode material have been proposed.

  As a method for supplying the electrode material, there is a method in which the electrode material is charged and electrostatically attached. In this method, the electrode material can be supplied thinly and evenly, and the electrode material that has not adhered can be recovered and reused, which is excellent in terms of productivity.

  Examples of the method of charging the electrode material include a method of charging the electrode material by friction, and a method of charging by directly applying a voltage to the electrode material using corona discharge.

For example, in Patent Document 1, a powdered electrode material containing a binder and an electrode active material is supplied onto a current collector, and the powdered electrode material is heated, whereby an electrochemical device is used on the current collector. A method of forming an electrode is disclosed. And as a method for supplying the powdered electrode material onto the current collector, a method of adhering by static electricity such as an electrostatic spraying method or an electrostatic fluid immersion method is exemplified. According to this method, it is possible to continuously mass-produce electrodes for electrochemical devices.
In Patent Document 2, a powder material for an electrode composed of activated carbon powder, a thermosetting resin, a binder resin, and a charge control agent is transferred onto a substrate composed of an organic fiber material by an electrophotographic process, and further a carbonization step. A method for producing a solid activated carbon electrode by passing through is disclosed. According to this method, it is said that an extremely thin solid activated carbon electrode can be manufactured stably.

International Publication No. 2004/077467 JP 2001-223142 A

As a problem for manufacturing a thin film electrode with high productivity, it is required to continuously supply a stable electrode material. For such a problem, a method of electrostatically supplying an electrode material is effective. However, when the electrode material is supplied electrostatically, improvement of the coating efficiency is important in terms of productivity. For such a problem, the method described in Patent Document 1 has a problem that the coating efficiency cannot be sufficiently increased.
In order to improve the coating efficiency of the electrode material, it is effective to add a charge control agent to the electrode material. However, since the method described in Patent Document 2 has a plurality of steps of a charging step, an electrostatic adhesion step, a transfer step, and a carbonization step, the coating efficiency cannot be sufficiently increased. There was a problem that the electrode for electrochemical devices could not be manufactured stably.
Accordingly, an object of the present invention is to provide a method for stably producing an electrode for an electrochemical device with high coating efficiency.

  As a result of intensive studies on the above problems, the present inventors have charged an electrode material comprising an electrode active material, a binder, a conductive additive, and a charge control resin, on at least one surface of the current collector. By supplying and forming the electrode layer, environmental stability and safety are improved, and the electrode material can be charged efficiently, so that the electrode material can be efficiently supplied onto the current collector. The inventors have found that it is possible to manufacture an electrode for an electrochemical element stably for a long time, and based on these findings, the following invention has been completed.

Thus, according to the present invention, an electrode material comprising an electrode active material, a binder, a conductive additive and a charge control resin is charged and formed on at least one surface of the current collector to form an electrode layer. A method for producing an electrode for an electrochemical device is provided.
In the method for producing an electrode for an electrochemical element of the present invention, the surface charge amount C (μ · coulomb / g) of the charge control resin is preferably in the range of 10 ≦ | C | ≦ 600.
In the method for producing an electrode for an electrochemical element of the present invention, the glass transition temperature of the charge control resin is preferably −50 ° C. to 150 ° C.
Furthermore, in the method for producing an electrode for an electrochemical element of the present invention, the content of the charge control resin is preferably in the range of 0.01 to 20 parts by weight with respect to 100 parts by weight of the electrode active material.
Furthermore, in the method for producing an electrode for an electrochemical element of the present invention, the electrode material is preferably composite particles.
Furthermore, in the method for producing an electrode for an electrochemical element of the present invention, the current collector is preferably a metal.
According to this invention, the electrode for electrochemical elements obtained by the said manufacturing method is provided.
Moreover, according to this invention, the electrochemical element formed using the said electrode for electrochemical elements is provided.
Furthermore, according to the present invention, the electrochemical element is preferably an electric double layer capacitor.

  According to the present invention, when the electrode material contains the charge control resin, the electrode material can be charged efficiently and uniformly. As a result, the electrode material can be efficiently supplied with a uniform thickness on the current collector for a long period of time, and as a result, an electrode for an electrochemical element having a uniform thickness and a low internal resistance is produced. It is possible to manufacture with good performance. The present invention can be suitably used particularly as a method for producing an electrode for an electric double layer capacitor, an electrode for a hybrid capacitor, and an electrode for a lithium ion secondary battery.

  In the method for producing an electrode for an electrochemical device of the present invention, an electrode material comprising an electrode active material, a binder, a conductive additive and a charge control resin is charged and supplied onto at least one surface of the current collector. Thus, an electrode layer is formed.

<Electrode material>
The electrode material used in the present invention is an electrode active material, a conductive auxiliary agent, a binder, a charge control resin, and other materials necessary for constituting an electrode, and usually has a solid particle form. Say what you are.

(Electrode active material)
What is necessary is just to select the electrode active material used for the electrode for electrochemical elements obtained by the manufacturing method of this invention according to the electrochemical element in which an electrode is utilized.

  When the electrode for an electrochemical element obtained by the production method of the present invention is used for an electrode for an electric double layer capacitor or a positive electrode for a hybrid capacitor, an allotrope of carbon is usually used as the electrode active material. Specific examples of the allotrope of carbon include activated carbon, polyacene, carbon whisker, and graphite, and these powders or fibers can be used. A preferred electrode active material is activated carbon, and specific examples include activated carbon made from phenol resin, rayon, acrylonitrile resin, pitch, coconut shell, and the like.

In the case where the electrode for an electrochemical element obtained by the production method of the present invention is used as a positive electrode for a lithium ion secondary battery, specifically, as an electrode active material, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , Lithium-containing composite metal oxides such as LiMn ₂ O ₄ , LiFePO ₄ and LiFeVO ₄ ; transition metal sulfides such as TiS ₂ , TiS ₃ and amorphous MoS ₃ ; Cu ₂ V ₂ O ₃ and amorphous V ₂ O · _P 2 _{O 5,} transition metal oxides such as _{MoO 3, V 2 O 5,} V 6 O 13 and the like. Furthermore, conductive polymers such as polyacetylene and poly-p-phenylene are listed. Preferred is a lithium-containing composite metal oxide.

  When the electrode for an electrochemical element obtained by the production method of the present invention is used for a negative electrode for a lithium ion secondary battery or a negative electrode for a hybrid capacitor, the electrode active material may be amorphous carbon, graphite, natural graphite. , Mesocarbon microbeads (MCMB), and carbonaceous materials such as pitch-based carbon fibers; conductive polymers such as polyacene; Si, Sn, Sb, Al, Zn, and W that can be alloyed with lithium. Crystalline carbonaceous materials such as graphite, natural graphite, and mesocarbon microbeads (MCMB) are preferable.

  The volume average particle diameter of the electrode active material used in the present invention is usually 0.1 to 100 μm, preferably 1 to 50 μm, more preferably 3 to 20 μm. These electrode active materials can be used alone or in combination of two or more.

(Conductive aid)
The conductive auxiliary agent used in the present invention is composed of an allotrope of particulate carbon that has conductivity and does not have pores that can form an electric double layer, and specifically includes furnace black, acetylene black, and kettle. Examples thereof include conductive carbon black such as chain black (registered trademark of Akzo Nobel Chemicals Besloten Fennaut Shap). Among these, acetylene black and furnace black are preferable.

  The volume average particle diameter of the conductive auxiliary agent used in the present invention is preferably smaller than the volume average particle diameter of the electrode active material, and the range is usually 0.001 to 10 μm, preferably 0.05 to 5 μm. Preferably it is 0.01-1 micrometer. When the volume average particle diameter of the conductive additive is within this range, high conductivity can be obtained with a smaller amount of use. These conductive assistants can be used alone or in combination of two or more. The amount of the conductive assistant is usually 0.1 to 50 parts by weight, preferably 0.5 to 15 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. When the amount of the conductive additive is within this range, the capacity of the electrochemical device using the obtained electrochemical device electrode can be increased and the internal resistance can be decreased.

(Binder)
The binder used in the present invention is not particularly limited as long as it is a compound that can bind the electrode active material and the conductive additive to each other. Examples of the type include fluorine-based polymers, diene-based polymers, acrylate-based polymers, and cellulose-based polymers. Among these, a diene polymer, an acrylate polymer, or a cellulose polymer is preferable, and the diene polymer or the acrylate polymer can increase the withstand voltage and increase the energy density of the electrochemical device. It is more preferable at the point which can do. In addition, when the method of charging the electrode material is frictional charging with a substance having a fluorine-containing group, the charge amount described later can be adjusted by utilizing the relationship of the charge train. For example, an acrylate polymer is preferable in that the charge amount can be increased because it is easier to be positively charged on a charged column than a diene polymer.

  The diene polymer is a homopolymer of a conjugated diene or a copolymer obtained by polymerizing a monomer mixture containing a conjugated diene, or a hydrogenated product thereof. The proportion of the conjugated diene in the monomer electrode material is usually 30% by weight or more, preferably 40% by weight or more, more preferably 50% by weight or more. Specific examples of the diene polymer include conjugated diene homopolymers such as polybutadiene and polyisoprene; aromatic vinyl / conjugated diene copolymers such as carboxy-modified styrene / butadiene copolymer (SBR); Copolymers of styrene / butadiene / methacrylic acid copolymer and aromatic vinyl / conjugated diene / carboxylic acid group-containing monomers such as styrene / butadiene / itaconic acid copolymer; acrylonitrile / butadiene copolymer (NBR) And vinyl cyanide / conjugated diene copolymers such as hydrogenated SBR and hydrogenated NBR.

The acrylate polymer is represented by the general formula (1): CH ₂ = CR ¹ —COOR ² (wherein R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group or a cycloalkyl group). Or a polymer obtained by polymerizing a monomer mixture containing the compound represented by the general formula (1). Specific examples of the compound represented by the general formula (1) include ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-amyl acrylate, Acrylates such as isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, hexyl acrylate, nonyl acrylate, lauryl acrylate, stearyl acrylate; ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n methacrylate -Butyl, isobutyl methacrylate, t-butyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isodecyl methacrylate, methacrylate Le lauryl, tridecyl methacrylate include methacrylates such as such as stearyl methacrylate. Among these, acrylate is preferable, and n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable in that the strength of the obtained electrode can be improved. The ratio of the monomer unit derived from the compound represented by the general formula (1) in the acrylate polymer is usually 50% by weight or more, preferably 70% by weight or more. When an acrylate polymer in which the proportion of the monomer unit derived from the compound represented by the general formula (1) is within the above range is used, the heat resistance is high and the internal resistance of the obtained electrode for an electrochemical device is reduced. it can.

  In addition to the compound represented by the general formula (1), a copolymerizable carboxylic acid group-containing monomer can be used for the acrylate polymer. Specific examples of the carboxylic acid group-containing monomer include monobasic acid-containing monomers such as acrylic acid and methacrylic acid; dibasic acid-containing monomers such as maleic acid, fumaric acid, and itaconic acid. Among these, a dibasic acid-containing monomer is preferable, and itaconic acid is particularly preferable in terms of enhancing the binding property with the current collector and improving the electrode strength. These monobasic acid-containing monomers and dibasic acid-containing monomers can be used alone or in combination of two or more. The amount of the carboxylic acid group-containing monomer in the monomer mixture at the time of copolymerization is usually 0.1 to 50 parts by weight, preferably 100 parts by weight with respect to 100 parts by weight of the compound represented by the general formula (1). Is in the range of 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight. When the amount of the carboxylic acid group-containing monomer is within this range, the binding property with the current collector is excellent, and the obtained electrode strength is increased.

  In addition to the compound represented by the general formula (1), a copolymerizable nitrile group-containing monomer can be used for the acrylate polymer. Specific examples of the nitrile group-containing monomer include acrylonitrile, methacrylonitrile, and the like. Among them, acrylonitrile is preferable in that the binding strength with the current collector is increased and the electrode strength can be improved. The amount of acrylonitrile in the monomer mixture at the time of copolymerization is usually 0.1 to 40 parts by weight, preferably 0.5 to 30 parts per 100 parts by weight of the compound represented by the general formula (1). Part by weight, more preferably in the range of 1 to 20 parts by weight. When the amount of acrylonitrile is within this range, the binding property with the current collector is excellent, and the obtained electrode strength is increased.

  The acrylate polymer may be a copolymer obtained by copolymerizing an alkyl styrene monomer or vinyl ester in addition to the monomer. Examples of the styrene monomer include styrene and styrene derivatives such as methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, diethyl styrene, triethyl styrene, propyl styrene, butyl styrene, hexyl styrene, heptyl styrene and octyl styrene. Vinyl esters include vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caproate, vinyl persate, vinyl laurate, vinyl stearate, vinyl benzoate, pt -Vinyl esters such as vinyl butylbenzoate and vinyl salicylate can be mentioned.

  The cellulose polymer is cellulose in which part or all of the hydroxyl groups of cellulose are substituted, and specific examples include nitrocellulose, acetylcellulose, and cellulose ether. Among these, carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, and cellulose ethers such as ammonium salts or alkali metal salts thereof are preferable, and carboxymethyl cellulose or ammonium salts or alkali metal salts thereof have binding properties with the current collector. It is more preferable in that the electrode strength can be improved.

  The amount of the binder used in the present invention is usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. It is a range. When the amount of the binder is in the above range, sufficient adhesion between the obtained electrode layer and the current collector can be secured, the capacity of the electrochemical device can be increased, and the internal resistance can be decreased. Further, when the amount of the binder is increased, the charge amount of the electrode material described later can be increased, and when the amount of the binder is decreased, the charge amount of the electrode material can be decreased.

(Charge control resin)
The charge control resin used in the present invention refers to a resin having a function of imparting chargeability to the electrode material used in the present invention. Examples of the charge control resin used in the present invention include a negative charge control resin and a positive charge control resin. It is preferable to use different charge control resins depending on whether the electrode material of the present invention is negatively charged or positively charged. Hereinafter, the negative charge control resin and the positive charge control resin will be described.

  The negative charge control resin has a substituent selected from a carboxyl group or a salt thereof, a phenol group or a salt thereof, a thiophenol group or a salt thereof, and a sulfonic acid group or a salt thereof in the side chain of the polymer. Examples thereof include resins. Examples of the salt of the substituent contained in the side chain of the polymer include salts with metals such as zinc, magnesium, aluminum, sodium, calcium, chromium, iron, manganese, cobalt; ammonium ion, pyridinium ion, imidazolium ion And salts with organic bases such as

  Among these, a resin having a sulfonic acid group or a salt thereof in the side chain of the polymer is preferable in that the charge amount can be improved. Specific examples include a resin obtained by copolymerizing a monovinyl monomer containing a sulfonic acid group or a salt thereof and another monovinyl monomer copolymerizable with the monovinyl monomer. Examples of other monovinyl monomers that can be copolymerized include ethylenically unsaturated carboxylic acid ester monomers, aromatic vinyl monomers, ethylenically unsaturated nitrile monomers, and vinyl esters.

  Examples of the monovinyl monomer containing a sulfonic acid group or a salt thereof include styrene sulfonic acid, sodium styrene sulfonate, potassium styrene sulfonate, 2-acrylamido-2-methylpropane sulfonic acid, sodium vinyl sulfonate, and methacryl sulfonic acid. Ammonium etc. are mentioned.

  Examples of the ethylenically unsaturated carboxylic acid ester monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid-2- And ethyl hexyl. Examples of the aromatic vinyl monomer include styrene, methyl styrene, vinyl toluene, chlorostyrene, and hydroxymethyl styrene. Examples of the ethylenically unsaturated nitrile monomer include (meth) acrylonitrile, fumaronitrile, α-chloroacrylonitrile, α-cyanoethylacrylonitrile and the like. Examples of the vinyl esters include vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl pivalate, vinyl benzoate, vinyl p-t-butylbenzoate, and vinyl salicylate.

  When the resin having a sulfonic acid group or a salt thereof in the side chain of the polymer is used as the negative charge control resin, the content ratio of the monomer unit of the monovinyl monomer containing a sulfonic acid group or a salt thereof is Preferably it is 0.5 to 15 weight%, More preferably, it is 1 to 10 weight%. When the content ratio of the monomer unit of the monovinyl monomer containing a sulfonic acid group or a salt thereof in the negative charge control resin is in the above range, the charge amount of the negative charge control resin can be sufficiently improved. .

The positive charge control resin has an amino group such as NH ₂ , —NHCH ₃ , —N (CH ₃ ) ₂ , —NHC ₂ H ₅ , —N (C ₂ H ₅ ) ₂ , —NHC ₂ H ₄ OH. Resins, and resins having functional groups in which they are ammonium chlorided. Such a resin is obtained by copolymerizing a monovinyl monomer containing an amino group and another monovinyl monomer copolymerizable therewith. Further, the copolymer obtained as described above can be obtained by ammonium chloride. Furthermore, although obtained by copolymerizing a monovinyl monomer containing an ammonium base and a monovinyl monomer copolymerizable therewith, it is not limited to these methods. As a monovinyl monomer copolymerizable with a monovinyl monomer containing an amino group or another monovinyl monomer copolymerizable with a monovinyl monomer containing an ammonium base, a negatively chargeable control resin is obtained. For that purpose.

  Examples of the monovinyl monomer containing an amino group include N, N-dimethylaminomethyl (meth) acrylate, N, N-diethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N , N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminobutyl (meth) acrylate, pN, N-dimethylaminophenyl (meth) acrylate, p- N, N-diethylaminophenyl (meth) acrylate, pN, N-dipropylaminophenyl (meth) acrylate, pN, N-dibutylaminophenyl (meth) acrylate, pN-laurylaminophenyl (meth) Acrylate, pN-stearylaminophenyl ( ) Acrylate, pN, N-dimethylaminobenzyl (meth) acrylate, pN, N-diethylaminobenzyl (meth) acrylate, pN, N-dipropylaminobenzyl (meth) acrylate, pN, Examples include N-dibutylaminobenzyl (meth) acrylate, pN-laurylaminobenzyl (meth) acrylate, pN-stearylaminobenzyl (meth) acrylate, acryloyloxymethylmorpholine, acryloyloxyethylmorpholine, and the like. .

  Furthermore, (meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylamino Ethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, pN, N-dimethylaminophenyl (meth) acrylamide, pN, N-diethylamino Phenyl (meth) acrylamide, pN, N-dipropylaminophenyl (meth) acrylamide, pN, N-dibutylaminophenyl (meth) acrylamide, pN-laurylaminophenyl (meth) acrylamide, pN -Stearylaminopheny (Meth) acrylamide, pN, N-dimethylaminobenzyl (meth) acrylamide, pN, N-diethylaminobenzyl (meth) acrylamide, pN, N-dipropylaminobenzyl (meth) acrylamide, pN , N-dibutylaminobenzyl (meth) acrylamide, pN-laurylaminobenzyl (meth) acrylamide, pN-stearylaminobenzyl (meth) acrylamide, 3- (dimethylamino) propyl (meth) acrylate, 2- Examples include aminostyrene, 4-aminostyrene, allylamine and the like.

  As the ammonium reagent used for ammonium-salting the copolymer, those usually used are used, for example, halogenated alkyls such as methyl iodide, ethyl iodide, methyl bromide, ethyl bromide; Examples include paratoluenesulfonic acid alkyl esters such as methyl sulfonate, ethyl paratoluenesulfonate, and propyl paratoluenesulfonate.

  The glass transition temperature of the charge control resin used in the present invention is preferably −50 to 150 ° C., more preferably 20 to 120 ° C., and most preferably 40 to 100 ° C. When the glass transition temperature of the charge control resin is in the above range, it is excellent in binding property with a small amount of use, strong in electrode strength, rich in flexibility, and can easily increase the electrode density by the pressing process at the time of electrode formation. it can.

  The surface charge amount C (μ · coulomb / g) of the charge control resin used in the present invention is preferably 10 ≦ | C | ≦ 600, more preferably 50 ≦ | C | ≦ 600, and particularly preferably 300 ≦ | C |. ≦ 600. The surface charge amount in the present invention is a charge amount with respect to an iron powder carrier measured by a blow-off charge amount measuring device (manufactured by Kyocera Chemical, equipment name “TB-200” or “TB-203”). When the surface charge amount C of the charge control resin is within the above range, the charge amount of the electrode material can be further sufficiently improved.

The content of the charge control resin used in the present invention in the electrode material is not particularly limited, but is preferably 0.01 to 20 parts by weight, more preferably 0.05 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. Particularly preferred is 0.1 to 5 parts by weight. When the content of the charge control resin in the electrode material is in the above range, the charge amount of the electrode material can be improved, and the coating efficiency can be further improved.
The method for containing the charge control resin is not particularly limited, and is a method in which the charge control resin and other electrode materials are charged into a mixer such as a Henschel mixer and stirred; composite particles are produced by the spray drying granulation method described later. In this case, the charge control resin is added to a dispersion obtained by mixing an electrode active material, which will be described later, a binder, a conductive additive, and, if necessary, a dispersant and other components in a solvent. Among them, a method of dissolving or dispersing is preferable, and among them, a method in which the charge control resin and the material constituting the other electrode material are charged into a mixer such as a Henschel mixer and stirred is preferable, and the electrode active material, the binder, and the conductive material are preferable. A method in which composite particles containing an auxiliary agent and the charge control resin are charged into a mixer such as a Henschel mixer and stirred is more preferable. As a method of containing the charge control resin, an electrode active material is obtained by using a method in which a composite particle containing an electrode active material, a binder and a conductive additive and a charge control resin are charged into a mixer such as a Henschel mixer and stirred. The charge control resin can be attached to the surface of the composite particles containing.

  In the production method of the present invention, the electrode material may contain the following materials necessary for constituting other electrodes.

(Dispersant etc.)
The dispersant is used by being dissolved in a slurry solvent, which will be described later, and uniformly dispersing the electrode active material, the conductive auxiliary agent, and the like in the solvent.
Specific examples of the dispersant include cellulosic polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose and hydroxypropylcellulose, and ammonium salts or alkali metal salts thereof; poly (meth) acrylates such as sodium poly (meth) acrylate Polyvinyl alcohol, modified polyvinyl alcohol, polyethylene oxide; polyvinyl pyrrolidone; polycarboxylic acid; various modified starches such as oxidized starch, phosphate starch, and casein; chitin; chitosan derivatives;
These dispersants can be used alone or in combination of two or more. Among these, a cellulose polymer is preferable, and carboxymethyl cellulose or an ammonium salt or an alkali metal salt thereof is particularly preferable.

  The amount of the dispersant used can be used within a range not impairing the effects of the present invention, and is not particularly limited, but is usually 0.1 to 10 parts by weight, preferably 100 parts by weight with respect to 100 parts by weight of the electrode active material. It is 0.5-5 weight part, More preferably, it is the range of 1-4 weight part. By using a dispersing agent, sedimentation and aggregation of solid content in the slurry can be suppressed. Moreover, since the clogging of the atomizer at the time of spray drying can be prevented, spray drying can be performed stably and continuously.

  Examples of other additives include a surfactant. Examples of the surfactant include amphoteric surfactants such as anionic, cationic, nonionic, and nonionic anions. Among them, anionic or nonionic surfactants that are easily thermally decomposed are preferable.

  Surfactant can be used individually or in combination of 2 or more types. The amount of the surfactant is not particularly limited, but is 0 to 50 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the electrode active material. It is.

  The electrode material used in the present invention has the above-mentioned electrode active material, conductive additive, binder, and charge control resin as suitable components, and has a particle shape containing a dispersant and other additives as necessary. It is preferable that the material (hereinafter also referred to as “composite particle”). In addition, it is more preferable to use externally added particles in which a charge control resin is externally added to the surface of a composite particle containing an electrode active material, a conductive additive, and a binder. When the electrode material is the external additive particle, it is preferable in that the difference in chargeability between different materials can be eliminated.

The production method of the composite particles is not particularly limited, and is a spray drying granulation method, a rolling bed granulation method, a compression granulation method, a stirring granulation method, an extrusion granulation method, a crushing granulation method, a fluidized bed granulation method. It can be produced by a known granulation method such as a granulation method, a fluidized bed multifunctional granulation method, a pulse combustion type drying method, or a melt granulation method. Among these, the spray-drying granulation method is preferable because composite particles in which the binder and the conductive auxiliary agent are unevenly distributed near the surface can be easily obtained.
The spray-drying granulation method includes a step of mixing an electrode active material, a binder, a conductive additive, and, if necessary, a dispersant and other components in a solvent to form a dispersion, and the dispersion Spraying the liquid to form composite particles. Specifically, in the composite particle forming step, the dispersion liquid is sprayed from an atomizer using a spray dryer, and the sprayed dispersion liquid is dried inside a drying tower, whereby an electrode contained in the dispersion liquid Spherical composite particles composed of an active material, a binder, and other components are formed. When composite particles obtained by the spray drying granulation method are used, the electrode for an electrochemical element of the present invention can be obtained with high productivity. In addition, the internal resistance of the electrode can be further reduced.

  In the case of producing composite particles by spray drying granulation, the solvent used for obtaining the dispersion is not particularly limited, but a solvent capable of dissolving the dispersant is preferably used. Specifically, water is usually used, but an organic solvent may be used, or a mixed solvent of water and an organic solvent may be used. Examples of the organic solvent include alkyl alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol; alkyl ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran, dioxane and diglyme; diethylformamide, dimethylacetamide and N-methyl- Amides such as 2-pyrrolidone and dimethylimidazolidinone; sulfur solvents such as dimethyl sulfoxide and sulfolane; and the like. Among these, alcohols are preferable as the organic solvent. When an organic solvent having a lower boiling point than water and water are used in combination, the drying rate can be increased during spray drying. Further, the dispersibility of the binder or the solubility of the dispersant varies depending on the amount or type of the organic solvent used in combination with water. Thereby, the viscosity and fluidity | liquidity of a slurry can be adjusted and production efficiency can be improved.

  The amount of the solvent used when preparing the slurry is an amount such that the solid content concentration of the slurry is usually in the range of 1 to 50% by mass, preferably 5 to 50% by mass, more preferably 10 to 30% by mass. . When the solid content concentration is in this range, the binder is preferably dispersed uniformly.

  The method or procedure for dispersing or dissolving the other components such as the electrode active material, the binder, the conductive aid and the dispersant in the solvent is not particularly limited. For example, the electrode active material, the binder, the conductive aid are dissolved in the solvent. A method of adding and mixing other components such as an agent and a dispersant; after dissolving the dispersant in the solvent, a binder (for example, latex) dispersed in the solvent is added and mixed, and finally the electrode active material And a method of adding and mixing a conductive assistant; adding and mixing an electrode active material and a conductive assistant to a binder dispersed in a solvent, and adding and mixing a dispersant dissolved in the solvent Methods and the like. Examples of the mixing means include mixing equipment such as a ball mill, a sand mill, a bead mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a homomixer, and a planetary mixer. Mixing is usually performed in the range of room temperature to 80 ° C. for 10 minutes to several hours.

  The viscosity of the slurry is usually in the range of 5 to 3000 mPa · s, preferably 10 to 1000 mPa · s, more preferably 15 to 500 mPa · s at room temperature. When the viscosity of the slurry is within this range, the productivity of the composite particles can be increased. Further, the lower the viscosity of the slurry, the smaller the spray droplets, and the smaller the volume average particle diameter of the resulting composite particles.

Next, the slurry obtained above is spray-dried and granulated to obtain composite particles. Spray drying is performed by spraying the slurry in hot air and drying. An atomizer is used as an apparatus used for spraying slurry. There are two types of atomizers: a rotating disk method and a pressure method. The rotating disk system is a system in which slurry is introduced almost at the center of a disk that rotates at a high speed, and the slurry is released out of the disk by the centrifugal force of the disk, and the slurry is atomized at that time. The rotational speed of the disk depends on the size of the disk, but is usually 5,000 to 50,000 rpm, preferably 20,000 to 45,000 rpm. The higher the rotational speed of the disk, the smaller the spray droplets and the smaller the weight average particle diameter of the resulting composite particles. Examples of the rotating disk type atomizer include a pin type and a vane type, and a pin type atomizer is preferable. A pin-type atomizer is a type of centrifugal spraying device that uses a spraying plate, and the spraying plate has a plurality of spraying rollers removably mounted on a concentric circle along its periphery between upper and lower mounting disks. It is made up of. Slurry can be introduced from the center of the spray plate, adheres to the spray roller by centrifugal force, moves outward on the roller surface, and finally sprays away from the roller surface. On the other hand, the pressurization method is a method in which the slurry is pressurized and sprayed from a nozzle to be dried.

  The temperature of the slurry to be sprayed is usually room temperature, but may be heated to room temperature or higher. Moreover, the hot air temperature at the time of spray-drying is 80-250 degreeC normally, Preferably it is 100-200 degreeC. In spray drying, the method of blowing hot air is not particularly limited, for example, a method in which the hot air and the spray direction flow in the horizontal direction, a method in which the hot air blows down at the top of the drying tower, and the sprayed droplet and hot air are in countercurrent contact. And a system in which sprayed droplets first flow in parallel with hot air and then drop by gravity to make countercurrent contact.

  The weight average particle diameter of the composite particles suitably used in the present invention is usually in the range of 0.1 to 1,000 μm, preferably 5 to 500 μm, more preferably 10 to 100 μm. When the weight average particle diameter of the composite particles is within this range, the composite particles are less prone to agglomerate, and electrostatic force against gravity is increased, which is preferable. The weight average particle diameter can be measured using a laser diffraction particle size distribution measuring apparatus.

  The composite particles are preferably spherical. Evaluation of whether the composite particles are spherical or not is a value calculated by (Ll−Ls) / {(Ls + Ll) / 2} where Ls is the short axis diameter of the composite particles and Ll is the long axis diameter. (Hereinafter referred to as “sphericity”). Here, the minor axis diameter Ls and the major axis diameter Ll are average values for 100 arbitrary composite particles measured from a photographic image obtained by observing the composite particles using a reflection electron microscope. The smaller this value, the closer the spherical composite particle is to a true sphere.

  For example, the particle observed as a square in the photographic image has a sphericity of 34.4%, so that the composite particle having a sphericity exceeding 34.4% is not at least spherical. The sphericity of the composite particles is preferably 20% or less, and more preferably 15% or less. When the sphericity of the composite particles is within the above range, the internal resistance of the electrochemical device including the electrode for an electrochemical device in which the electrode layer made of the composite particles is formed can be reduced, and the output characteristics can be improved.

  The composite particles obtained by the above production method can be subjected to post-treatment after the production of the particles, if necessary. As a specific example, the composite particle surface is modified by mixing the composite particle with the above-mentioned electrode active material, conductive additive, binder, dispersant or other additive, and the fluidity of the composite particle. Can be improved or reduced, continuous pressure moldability can be improved, the electrical conductivity of the composite particles can be improved, and the average charge amount of the composite particles can be adjusted.

<Current collector>
As the current collector used in the present invention, for example, a metal, carbon, a conductive polymer, or the like can be used, and a metal is preferably used. As the current collector metal, aluminum, platinum, nickel, tantalum, titanium, stainless steel, copper, other alloys and the like are usually used. Among these, it is preferable to use copper, aluminum, or an aluminum alloy in terms of conductivity and voltage resistance.

  The shape of the current collector used in the present invention is not particularly limited, but is usually a film shape or a sheet shape, and the sheet current collector may have pores. The sheet-like current collector may have a shape such as an expanded metal, a punching metal, or a net. When a sheet-like current collector having pores is used, the capacity per volume of the obtained electrode can be increased. When the sheet-like current collector has holes, the ratio of the holes is preferably 10 to 79 area%, more preferably 20 to 60 area%.

  Although the thickness of a collector is suitably selected according to the intended purpose, it is 1-200 micrometers normally, Preferably it is 5-100 micrometers, More preferably, it is 10-50 micrometers. When the thickness of the current collector is within this range, the resistance of electron movement can be reduced, and the internal resistance can be reduced.

In the present invention, an adhesive layer is preferably formed on at least one surface of the current collector. The adhesive layer is more preferably conductive because the interface resistance between the electrode layer and the current collector can be reduced. The adhesive layer can be formed by applying and drying an adhesive on the surface of the current collector.
The adhesive is obtained by dispersing a conductive assistant powder, a binder, and a dispersant added as necessary in water or an organic solvent. Examples of the conductive assistant used in the conductive adhesive include silver, nickel, gold, graphite, acetylene black, and ketjen black, and graphite and acetylene black are preferable. As the binder used for the conductive adhesive, any of those exemplified as the binder constituting the electrode layer described above can be used. Moreover, water glass, an epoxy resin, a polyamide-imide resin, a urethane resin, etc. can also be used, and these can be used individually or in combination of 2 or more types, respectively.
As the binder used for the conductive adhesive, an acrylate polymer, an ammonium salt or alkali metal salt of carboxymethyl cellulose, water glass, or a polyamideimide resin is preferable. Moreover, as a dispersing agent used for an electroconductive adhesive agent, the dispersing agent or surfactant which may be used for the electrode layer of the manufacturing method of the said invention can be used.
The method for forming the adhesive layer used in the present invention is not particularly limited. For example, by a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating, an electrostatic coating method, or the like. , Formed on the current collector.

The thickness of the adhesive layer is usually 0.01 to 20 μm, preferably 0.1 to 10 μm, particularly preferably 1 to 5 μm. When the thickness of the adhesive layer is within the above range, the internal resistance of the electrochemical device having the electrochemical device electrode obtained by the production method of the present invention can be further reduced.

<Charging>
In the present invention, charging the electrode material means charging the electrode material positively or negatively by applying a treatment to the electrode material. The method for charging the electrode material is not particularly limited, and examples thereof include a method for charging by directly applying a voltage to the electrode material, a method for charging the electrode material by friction, and the like.

  Examples of the method for charging the electrode material by directly applying a voltage include a charging method using corona discharge. The charging method using the corona discharge is a method of charging the electrode material by spraying the vicinity of the corona discharge electrode when spraying the electrode material on the current collector, or the fluidizing state (fluidized bed) of the electrode material, Among them, there is a method in which a corona discharge electrode is installed and charged.

  As a method for triboelectrically charging the electrode material, a method is used in which the electrode material and a substance that easily charges the electrode material are brought into contact with each other and charged using a charging train. The charged column is inherent to a material, and has a relative order of easiness of charging from a material that is easily charged negatively to a material that is easily charged positively. The more the two substances to be rubbed are apart from each other on the charged column, the more charged each becomes. Therefore, on the charged column, the electrode material can easily be brought into contact with the substance separated from the electrode material by the electrode material. Can be charged. When the electrode material is charged positively, it is brought into contact with polytetrafluoroethylene, vinyl chloride, etc. When the electrode material is charged negatively, it is brought into contact with the electrode material with asbestos, nylon, etc. Thus, each can be charged.

  The electrode material may be charged by mixing the plurality of electrode materials and the charge control resin, but since the difference in chargeability between different materials can be eliminated, the above electrode material is made into composite particles. It is preferable to charge things.

<Formation of electrode layer>
(Electrode material supply method)
In the present invention, the electrode layer is formed by supplying the charged electrode material onto at least one surface of the current collector. There is no particular limitation on the method of supplying the charged electrode material onto the current collector. For example, a charged electrode material may be sprayed and supplied onto a grounded current collector as in electrostatic powder coating, or an installed current collector as in electrostatic screen printing. The electrode material charged on top may be transferred. Further, charging in the present invention and electrode material supply may be performed simultaneously.

  Then, the current collector and the electrode material supplied on the one surface by the supply method are pressurized with a pair of heating rolls to improve the adhesion between the current collector and the electrode layer. In this step, the electrode material heated as necessary may be formed into a sheet-like electrode layer with a pair of rolls. The temperature of the electrode material supplied is preferably 40 to 160 ° C, more preferably 70 to 140 ° C. When an electrode material in this temperature range is used, there is no slip of the electrode material on the surface of the press roll, and the electrode material is continuously and uniformly supplied to the press roll. An electrode sheet for an electrochemical element with small variations can be obtained.

  In the present invention, the temperature of the heating roll at the time of molding is preferably 0 to 200 ° C., preferably higher than the melting point or glass transition temperature of the binder, and 20 ° C. or higher than the melting point or glass transition temperature of the binder. Higher is more preferable. In the case of using a press roll, the forming speed is usually 10 m / min or more, preferably 20 to 200 m / min, more preferably 30 to 80 m / min, in order to make the moldability higher and to make the film easier. . Moreover, although the press linear pressure between the rolls for a press is not prescribed | regulated, Preferably it is the point which can make the electrode intensity | strength of the electrode obtained high, Preferably it is 0.2-30 kN / cm, More preferably, it is 0.5-10 kN / cm. cm.

  In the present invention, the arrangement of the pair of heating rolls is not particularly limited, but is preferably arranged substantially horizontally or substantially vertically. When arranged substantially horizontally, the current collector is continuously supplied between a pair of rolls, and the electrode material is supplied to at least one of the rolls, so that the electrode material is placed in the gap between the current collector and the rolls. The electrode layer can be formed by being supplied and pressurized. In the case of disposing substantially vertically, the current collector is conveyed in the horizontal direction, an electrode material is supplied onto the current collector, and a layer of electrode material is formed. After the supplied electrode material layer is leveled with a blade or the like as necessary, the current collector is supplied between a pair of rolls, and the electrode layer can be formed by pressurization.

  In order to eliminate the thickness variation of the molded body, increase the density, and increase the capacity, further pressurization may be performed as necessary. The post-pressing method is generally a press process using a roll. In the roll press step, two cylindrical rolls are arranged vertically in a balanced manner at a narrow interval, each is rotated in the opposite direction, and the electrodes are sandwiched and pressed between them. The roll may be temperature controlled, such as heated or cooled.

<Electrodes for electrochemical devices>
The electrode for an electrochemical element of the present invention is obtained by the method for producing an electrode for an electrochemical element of the present invention.
The thickness of the electrode layer of the electrode for an electrochemical element obtained by the production method of the present invention varies depending on the type of electrochemical element, but is usually 10 μm to 200 μm, preferably 30 to 100 μm. When the thickness of the electrode layer is within this range, an electrode for an electrochemical element having a balance between internal resistance and energy density is preferable. The electrode for an electrochemical device is composed of a current collector layer, and an electrode layer containing an electrode active material, a binder, a conductive additive and a charge control resin, and if necessary, an adhesive layer, a separator There may be layers.

<Electrochemical element>
The electrochemical element of the present invention comprises the electrode for an electrochemical element of the present invention. Examples of the electrochemical element include a lithium ion secondary battery, an electric double layer capacitor, and a hybrid capacitor. An electric double layer capacitor is preferable.

  An electric double layer capacitor is comprised with an electrode, a separator, and electrolyte solution, and uses the electrode for electrochemical elements of this invention as said electrode.

  The separator is not particularly limited as long as it can insulate between the electrodes and allow a cation and an anion to pass therethrough. Specifically, polyolefins such as polyethylene and polypropylene, microporous membranes or nonwoven fabrics made of rayon or glass fiber, and porous membranes mainly made of pulp called electrolytic capacitor paper can be used. The separator is disposed between the electrodes so that the pair of electrode layers face each other, and an element is obtained. Although the thickness of a separator is suitably selected according to a use purpose, Usually, it is 1-100 micrometers, Preferably it is 10-80 micrometers, More preferably, it is 20-50 micrometers.

The electrolytic solution is usually composed of an electrolyte and a solvent. The electrolyte may be cationic or anionic. As the cationic electrolyte, (1) imidazolium, (2) quaternary ammonium, (3) quaternary phosphonium, (4) lithium and the like as shown below can be used.
(1) Imidazolium 1,3-Dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-diethylimidazolium, 1,2,3-trimethylimidazolium, 1,2,3,4-tetra Methylimidazolium, 1,3,4-trimethyl-ethylimidazolium, 1,3-dimethyl-2,4-diethylimidazolium, 1,2-dimethyl-3,4-diethylimidazolium, 1-methyl-2, 3,4-triethylmethylimidazolium, 1,2,3,4-tetraethylimidazolium, 1,3-dimethyl-2-ethylimidazolium, 1-ethyl-2,3-dimethylimidazolium, 1,2,3 -Triethylimidazolium, etc. (2) Quaternary ammonium tetramethylammonium, ethyltrimethylammonium, diethyl Tetraalkylammonium such as methylammonium, triethylmethylammonium, tetraethylammonium, trimethylpropylammonium, etc. (3) Quaternary phosphonium Tetramethylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, methyltriethylphosphonium, methyltributylphosphonium, dimethyldiethylphosphonium 4) Lithium

In addition, examples of the anionic electrolyte include PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , N (RfSO ₃ ) ²⁻ , C (RfSO ₃ ) ³⁻ , RfSO ₃ ⁻ (Rf is 1 carbon number, respectively). ˜12 fluoroalkyl groups), F ⁻ , ClO ₄ ⁻ , AlCl ₄ ⁻ , AlF ₄ ^{− and the} like. These electrolytes can be used alone or in combination of two or more.

  The solvent of the electrolytic solution is not particularly limited as long as it is generally used as a solvent for the electrolytic solution. Specific examples include carbonates such as propylene carboat, ethylene carbonate, butylene carbonate, ethylmethyl carbonate, and dimethyl carbonate; lactones such as γ-butyrolactone; sulfolanes; nitriles such as acetonitrile. These can be used alone or as a mixed solvent of two or more. Of these, carbonates are preferred.

  The electrochemical element of the present invention is obtained by impregnating the above element with an electrolytic solution. Specifically, the capacitor element can be manufactured by winding, stacking, or folding into a container as necessary, and pouring the electrolyte into the container and sealing it. Further, a device in which an element is previously impregnated with an electrolytic solution may be stored in a container. Any known container such as a coin shape, a cylindrical shape, or a square shape can be used as the container.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further more concretely, this invention is not limited to these Examples. In the examples and comparative examples, “part” and “%” are based on weight unless otherwise specified.

<Test method>
(Coating efficiency)
The coating efficiency to the current collector is calculated from the weight of the supplied electrode material and the weight of the electrode material in which the electrode material layer is formed on the current collector according to the following formula. The higher the coating efficiency, the better.
Coating efficiency (%) = weight of electrode material deposited on current collector / weight of supplied electrode material × 100

(Internal resistance)
The internal resistance is measured by performing charge / discharge operation after allowing the produced cell to stand for 24 hours. Charging is performed at a constant current of 100 mA, and the internal resistance is calculated from the voltage drop after 0.1 seconds of discharge and the constant current value. The smaller the internal resistance value, the better.

<Example 1>
100 parts of a high-purity activated carbon powder “Kuraray Coal YP-17D” (manufactured by Kuraray Chemical Co., Ltd.) having a specific surface area of 1,800 m ² / g and a volume average particle size of 5 μm as an electrode active material, and a volume average particle size of 0. 40% aqueous dispersion of 31 μm acrylate polymer (copolymer obtained by emulsion polymerization of n-butyl acrylate 40% by weight, ethyl methacrylate 40% by weight, n-butyl methacrylate 17% by weight, methacrylic acid 3% by weight) 5 parts in terms of solid content, 5 parts of acetylene black (Denka black powder; manufactured by Denki Kagaku Kogyo Co., Ltd.) having an average particle size of 0.7 μm as a conductive auxiliary agent, and ammonium salt “DN-800H” of carboxymethyl cellulose as a dispersing agent 1.4 parts of a 1.5% aqueous solution (manufactured by Daicel Chemical Industries) in terms of solid content and 348.7 parts of ion-exchanged water were added. Kisa "solid concentration mixed with stirring at (manufactured by PRIMIX Corporation) to obtain a 20% slurry. The pH of the slurry was 7.6 at 23 ° C. This slurry was adjusted to pH 8.5 with 25% aqueous ammonia, and using a spray dryer (OC-16; manufactured by Okawara Chemical Co., Ltd.), a rotating disk type atomizer (diameter 65 mm) with a rotational speed of 40,000 rpm and hot air Spray drying granulation was performed under the conditions of a temperature of 150 ° C. and a particle recovery outlet temperature of 90 ° C. to obtain composite particles of an electrode material. The composite particles had a weight average particle size of 25 μm and a sphericity of 8%.
100 parts of the composite particles and a styrene acrylic resin “QA-1150” (manufactured by Nippon Paint Co., Ltd.) 0.2 having a surface charge amount of +30 μC / g, a glass transition temperature of 82 ° C. and an average particle size of 0.07 μm as a positive charge control resin. Were mixed for 10 minutes using a Henschel mixer (manufactured by Mitsui Miike Co., Ltd.) to obtain particles (externally added particles) in which the charge control resin was adhered to the composite particles.

  100 parts of carbon black having a volume average particle size of 0.7 μm, and 4.0 parts of a carboxymethyl cellulose (DN-10L; manufactured by Daicel Chemical Industries) as a dispersant, 4 parts in terms of solid content, are a binder. A 40% aqueous dispersion of an acrylate polymer having a number average particle size of 0.25 μm is mixed with 8 parts in terms of solid content and ion-exchanged water so that the total solid content concentration becomes 30%, and a conductive adhesive layer A slurry for formation was prepared.

  The slurry for forming the conductive adhesive was applied to a current collector made of an aluminum foil having a thickness of 30 μm, and dried at 120 ° C. for 10 minutes to form a conductive adhesive layer having a thickness of 4 μm. Then, the collector which formed the conductive adhesive layer on the surface was installed horizontally.

  Next, friction charging electrostatic powder coating machine MTR-100VTmini manufactured by Asahi Sunac Co., Ltd. and friction charging electrostatic powder manual gun T-2m type L7 manufactured by Asahi Sunac Co., Ltd. (the inner sleeve and outer sleeve are made of polytetrafluoroethylene) And charging the external additive particles onto the adhesive layer of the current collector to form an electrode layer to obtain an electrode for an electrochemical device. Specifically, the external additive particles were put into a hopper of the powder coating machine, the rotation speed of a screw feeder for quantitative supply was adjusted, and external additive particles were supplied at 90 g / min. Moreover, the electrode material was supplied to the conductive adhesive layer of the said collector from the upper part by making the conveyance air pressure from the said powder manual gun into 0.4 Mpa. The external additive particles were charged by friction when passing through the gap between the inner sleeve and the outer sleeve of the powder manual gun. The coating efficiency was 35%.

The current collector on which this electrode material layer is formed is supplied to a roll (roll temperature 120 ° C., press linear pressure 4 kN / cm) of a roll press machine (pressed rough surface heat roll, manufactured by Hirano Giken Kogyo Co., Ltd.). A sheet-like thickened electrode layer is formed by pressure forming, and this is punched out into a square of 5 cm to produce an electrode for an electric double layer capacitor having an electrode layer thickness of 60 μm and an electrode layer density of 0.58 g / cm ³ did.

<Example 2>
Other than using 1.0 part of a styrene acrylic resin “FS-401” (manufactured by Nippon Paint Co., Ltd.) having a surface charge amount of +80 μC / g, a glass transition temperature of 102 ° C., and an average particle size of 0.06 μm as the positive charge control resin. Produced an electrode for an electric double layer capacitor having an electrode layer thickness of 60 μm and an electrode layer density of 0.58 g / cm ^{3 in} the same manner as in Example 1. The coating efficiency was 47%.

<Example 3>
Other than using 3.0 parts of a styrene acrylic resin “FS-501” (manufactured by Nippon Paint Co., Ltd.) having a surface charge amount of +320 μC / g, a glass transition temperature of 93 ° C. and an average particle size of 0.5 μm as a positive charge control resin Produced an electrode for an electric double layer capacitor having an electrode layer thickness of 60 μm and an electrode layer density of 0.58 g / cm ^{3 in} the same manner as in Example 1. The coating efficiency was 65%.

<Example 4>
Other than using 0.05 parts of a styrene acrylic resin “MP-5500” (manufactured by Soken Chemical Co., Ltd.) having a surface charge amount of +450 μC / g, a glass transition temperature of 105 ° C., and an average particle size of 0.4 μm as a positive charge control resin. Produced an electrode for an electric double layer capacitor having an electrode layer thickness of 60 μm and an electrode layer density of 0.58 g / cm ^{3 in} the same manner as in Example 1. The coating efficiency was 50%.

<Comparative Example 1>
An electrode for an electric double layer capacitor having an electrode layer thickness of 60 μm and an electrode layer density of 0.58 g / cm ³ was produced in the same manner as in Example 1 except that the charge control resin was not added. The coating efficiency was 15%.

<Comparative example 2>
Except that the inner and outer sleeves made of stainless steel of the same shape were replaced with the stainless steel of the same shape of the friction charging electrostatic powder coating gun T-2m type L7, and the electrode material was not charged In the same manner as in Example 1, an electrode for an electric double layer capacitor having an electrode layer thickness of 60 μm and an electrode layer density of 0.58 g / cm ³ was produced. The coating efficiency was 5%.

  The electrodes obtained in the above Examples and Comparative Examples were impregnated with an electrolytic solution (1.0 mol / L of propylene carbonate solution of tetraethylammonium tetrafluoroborate) at room temperature for 1 hour, and then the two electrodes were cellulose separators ( A laminated cell-shaped electric double layer capacitor was manufactured by placing the electrodes so as to face each other through TF40 (manufactured by Nippon Kogyo Paper Industries Co., Ltd.) so that the electrodes do not come into electrical contact with each other. And the internal resistance of the produced electric double layer capacitor was measured. In addition, it shows by a relative value when the value of the internal resistance of the comparative example 1 is 100%. The results of the above examples and comparative examples are shown in Table 1.

From the results in Table 1, the following can be understood. According to the present invention, as shown in Examples 1 to 4, an electrode material containing an electrode active material, a binder, a conductive assistant and a charge control resin is used, and the electrode material is charged and collected. By supplying on an electric body, the electrode for electrochemical elements which can reduce the internal resistance of the obtained electrochemical element with high coating efficiency can be obtained stably.
On the other hand, since Comparative Example 1 does not contain the charge control resin, the coating efficiency is inferior, the thickness of the electrode layer is not uniform, and the internal resistance is inferior. Comparative Example 2 contains a charge control resin but is not charged, so that the coating efficiency is poor, the supply of electrode material is not uniform, and the internal resistance is poor.

  The method for producing an electrode for an electrochemical device of the present invention is excellent in internal resistance and has a high coating efficiency of electrode material, so that it can produce an electrode such as an electric double layer capacitor electrode, a hybrid capacitor electrode, a lithium ion secondary battery with high productivity Can be suitably used.

  While the present invention has been described in connection with the most practical and preferred embodiments at the present time, the invention is not limited to the embodiments disclosed herein. The method of manufacturing an electrode for an electrochemical device with such a change is also within the technical scope of the present invention without departing from the spirit or idea of the invention that can be read from the claims and the entire specification. It must be understood as included.

Claims (8)

  An electrode material comprising externally added particles obtained by externally adding a particulate charge control resin to the surface of a composite particle comprising an electrode active material, a binder and a conductive additive is charged, and at least on the current collector A method for producing an electrode for an electrochemical element, wherein an electrode layer is formed by supplying on one surface.   2. The method for producing an electrode for an electrochemical element according to claim 1, wherein a surface charge amount C (μ · coulomb / g) of the charge control resin is in a range of 10 ≦ | C | ≦ 600.   The method for producing an electrode for an electrochemical device according to claim 1 or 2, wherein the charge control resin has a glass transition temperature of -50 ° C to 150 ° C.   The content of the charge control resin is in the range of 0.01 to 20 parts by weight with respect to 100 parts by weight of the electrode active material. The electrode for an electrochemical element according to any one of claims 1 to 3. Production method.   The method for producing an electrode for an electrochemical element according to claim 1, wherein the current collector is a metal.   The electrode for electrochemical elements obtained by the manufacturing method in any one of Claims 1-5.   An electrochemical element comprising the electrode for an electrochemical element according to claim 6.   The electrochemical device according to claim 7, wherein the electrochemical device is an electric double layer capacitor.