JP2011134807A - Electrode for electrochemical element and electrochemical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for electrochemical element with excellent impregnating ability with electrolyte and an electrode intensity and increasing its electrode density, and to provide an electrochemical element increasing an energy density and an output density by reducing an internal resistance. <P>SOLUTION: In the electrode for electrochemical element, an electrode composition layer containing an electrode active material, a conductive agent, a binding agent, and a high molecular material of which solubility parameter is 12-17 (cal/cm<SP>3</SP>)<SP>1/2</SP>is formed on a collector. A weight average molecular weight of the high molecular material is preferably 5,000-500,000. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrode for an electrochemical element and an electrochemical element. More specifically, the present invention relates to an electrode for an electrochemical element and an electrochemical element that are excellent in impregnation with an electrolyte, increase electrode density, reduce internal resistance, and increase energy density, output density, and durability.

  Utilizing the small size, light weight, high energy density, and the ability to repeatedly charge and discharge, electrochemical devices such as lithium ion secondary batteries, electric double layer capacitors, and lithium ion capacitors are rapidly expanding their demand. ing. Lithium-ion secondary batteries have a relatively high energy density, so they are used in the fields of mobile phones and notebook personal computers. Electric double layer capacitors can be charged and discharged rapidly, so they can be used for small memory backups such as personal computers. It is used as a power source. Furthermore, the electric double layer capacitor is expected to be applied as a large power source for electric vehicles. In addition, lithium ion capacitors that take advantage of lithium ion secondary batteries and electric double layer capacitors are attracting attention because of their high energy density and power density. With the expansion and development of applications, these electrochemical elements are required to be further improved, such as low resistance, high capacity, high durability, and improved mechanical properties.

  For example, an electric double layer capacitor has polarizable electrodes on the positive electrode and the negative electrode, and can increase the operating voltage by using an organic electrolyte, and can increase the energy density by increasing the electrode density. On the other hand, by increasing the electrode density, it becomes difficult to move the electrolyte solution in the electrode composition layer constituting the electrode, the electrode strength is decreased, and the internal resistance is increased, that is, the output density is decreased. There was a problem. Therefore, various studies have been conducted to solve these problems.

  For example, Patent Document 1 includes a current collector, an anchor coat layer made of carbon black and a binder, and a polarizable electrode layer made of activated carbon powder, carbon black and a binder, and the current collector and the anchor coat layer An electrode for an electric double layer capacitor provided with an adhesive layer made of a phosphorus compound has been proposed. According to Patent Document 1, an increase in resistance between the current collector and the polarizable electrode layer can be prevented, and the resistance of the capacitor can be reduced.

  Patent Document 2 proposes an electrode for an electric double layer capacitor in which a polarizable electrode layer made of composite particles containing activated carbon powder, carbon black and a binder is formed on a current collector. According to Patent Document 2, the composite particles can reduce the electron transfer resistance and the ion diffusion resistance, and the resistance of the capacitor can be reduced.

JP 2007-227732 A JP 2007-053278 A

However, according to the study by the present inventors, the electrodes described in Patent Documents 1 and 2 can reduce the internal resistance to some extent, but the impregnation property to the electrolytic solution and the electrode strength are insufficient. I understood it.
Therefore, the present invention makes it possible to increase the energy density and the output density by reducing the internal resistance and the electrode for an electrochemical element that is excellent in the impregnation property to the electrolyte and the electrode strength and can increase the electrode density. An object is to provide an electrochemical element.

As a result of intensive studies to achieve the above object, the present inventor has determined the solubility parameter in addition to the electrode active material, the conductive agent and the binder to the electrode composition layer constituting the electrode for an electrochemical device. By containing a polymer substance in the range, the impregnation into the electrolyte, the electrode strength and the electrode density are increased, and as a result, the capacity of the electrochemical device using the electrode for electrochemical devices is improved, and the internal It has been found that resistance is reduced and energy density, power density and durability are improved.
The present invention has been completed based on these findings.

The present invention for solving the above problems includes the following matters as a gist: (1) An electrode active material, a conductive agent, a binder, and a solubility parameter are 12 to 17 (cal / cm ³ ) ^{1 / 2.} An electrode for an electrochemical element, wherein an electrode composition layer comprising a polymer material ² is formed.
(2) The electrode for an electrochemical element according to the above (1), wherein the polymer substance has a weight average molecular weight of 5,000 to 500,000.
(3) The electrode for an electrochemical element according to the above (1) or (2), wherein the polymer substance is in the form of particles.
(4) The electrode for an electrochemical element according to (3), wherein the polymer substance has a number average particle diameter of 0.001 to 1 μm.
(5) The electrode for an electrochemical element according to any one of (1) to (4), wherein the polymer substance has a nitrile group.
(6) The electrode for an electrochemical element according to any one of (1) to (5), wherein the content of the polymer substance is 0.1 to 20 parts by weight with respect to 100 parts by weight of the electrode active material.
(7) The electrode composition layer is composed of composite particles including an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 (1 The electrode for electrochemical devices according to any one of (6) to (6).
(8) The electrode for an electrochemical element according to any one of (1) to (7), wherein the current collector has a conductive adhesive layer.
(9) An electrochemical element having the electrode for an electrochemical element according to any one of (1) to (8).

  By using the electrode for an electrochemical device of the present invention, an electrochemical device having high electrolyte impregnation, electrode strength and electrode density, low internal resistance, excellent energy density, power density and durability can be easily obtained. Can be manufactured. The electrochemical element of the present invention includes a memory backup power source for a personal computer, a portable terminal, etc., a power source for instantaneous power failure countermeasures such as a personal computer, application to an electric vehicle or a hybrid vehicle, a solar power generation energy storage system used in combination with a solar cell, a battery, It can be suitably used for various applications such as a combined load leveling power source.

The electrode for an electrochemical device of the present invention includes an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 on a current collector. An electrode composition layer is formed.

(Electrode active material)
The electrode active material used in the present invention is a substance that transfers electrons in an electrode for an electrochemical element. The electrode active material mainly includes an active material for a lithium ion secondary battery, an active material for an electric double layer capacitor, and an active material for a lithium ion capacitor.

Examples of the active material for a lithium ion secondary battery include a positive electrode and a negative electrode. As the electrode active material used for the positive electrode of a lithium ion secondary battery electrode, _{specifically, LiCoO 2, LiNiO 2, LiMnO} 2, LiMn 2 O 4, LiFePO 4, lithium-containing composite metal oxides such as LiFeVO _4; Transition metal sulfides such as TiS ₂ , TiS ₃ , and amorphous MoS ₃ ; Cu ₂ V ₂ O ₃ , amorphous V ₂ O · P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O _13, etc. These transition metal oxides are exemplified. Furthermore, conductive polymers such as polyacetylene and poly-p-phenylene are listed. Preferred is a lithium-containing composite metal oxide.

  Specific examples of the electrode active material used for the negative electrode of the lithium ion secondary battery electrode include carbonaceous materials such as amorphous carbon, graphite, natural graphite, mesocarbon microbeads (MCMB), and pitch-based carbon fibers; polyacene And the like, and the like. Crystalline carbonaceous materials such as graphite, natural graphite, and mesocarbon microbeads (MCMB) are preferable.

  The shape of the electrode active material used for the electrode for a lithium ion secondary battery is preferably a granulated particle. When the shape of the particles is spherical, a higher density electrode can be formed during electrode molding.

  The volume average particle diameter of the electrode active material used for the electrode for a lithium ion secondary battery is usually 0.1 to 100 μm, preferably 1 to 50 μm, more preferably 5 to 20 μm for both the positive electrode and the negative electrode.

The tap density of the electrode active material used for the electrode for the lithium ion secondary battery is not particularly limited, but preferably 2 g / cm ³ or more for the positive electrode and 0.6 g / cm ³ or more for the negative electrode.

  As the electrode active material used for the electric double layer capacitor electrode, a carbon allotrope is usually used. 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.

  The volume average particle diameter of the electrode active material used for the electric double layer capacitor electrode is usually 0.1 to 100 μm, preferably 1 to 50 μm, and more preferably 5 to 20 μm.

The specific surface area of the electrode active material used in the electrode for an electric double layer capacitor, ^{30 m} 2 / g or more, preferably 500~5,000m ² / g, and more preferably are from 1,000~3,000m ² / g preferable. Since the density of the obtained electrode composition layer tends to decrease as the specific surface area of the electrode active material increases, an electrode composition layer having a desired density can be obtained by appropriately selecting the electrode active material.

  Electrode active materials used for electrodes for lithium ion capacitors include positive electrodes and negative electrodes. The electrode active material used for the positive electrode of the lithium ion capacitor electrode is not particularly limited as long as it can reversibly carry lithium ions and anions such as tetrafluoroborate. Specifically, an allotrope of carbon is usually used, and electrode active materials used in electric double layer capacitors can be widely used. When carbon allotropes are used in combination, two or more types of carbon allotropes having different average particle diameters or particle size distributions may be used in combination. Further, a polyacene organic semiconductor (PAS) which is a heat-treated product of an aromatic condensation polymer and has a polyacene skeleton structure having a hydrogen atom / carbon atom atomic ratio of 0.50 to 0.05 can also be used suitably. . Preferably, it is an electrode active material used for the electrode for electric double layer capacitors.

  The electrode active material used for the negative electrode of the electrode for lithium ion capacitors is a substance that can reversibly carry lithium ions. Specifically, electrode active materials used in the negative electrode of lithium ion secondary batteries can be widely used. Preferred examples include crystalline carbon materials such as graphite and non-graphitizable carbon, and polyacene-based materials (PAS) described as the positive electrode active material. These carbon materials and PAS are obtained by carbonizing a phenol resin or the like, activated as necessary, and then pulverized.

  The shape of the electrode active material used for the electrode for a lithium ion capacitor is preferably a granulated particle. When the shape of the particles is spherical, a higher density electrode can be formed during electrode molding.

  The volume average particle diameter of the electrode active material used for the lithium ion capacitor electrode is usually 0.1 to 100 μm, preferably 1 to 50 μm, more preferably 5 to 20 μm for both the positive electrode and the negative electrode. These electrode active materials can be used alone or in combination of two or more.

(Conductive agent)
Examples of the conductive agent used in the present invention include those composed of an allotrope of particulate carbon which has conductivity and does not have pores capable of forming an electric double layer. Specific examples include conductive carbon blacks such as furnace black, acetylene black, and ketjen black (registered trademark of Akzo Nobel Chemicals Bethloten Fennaut Shap). Among these, acetylene black and furnace black are preferable.

  The volume average particle diameter of the conductive agent used in the present invention is preferably smaller than the volume average particle diameter of the electrode active material, and the range thereof is usually 0.001 to 10 μm, preferably 0.05 to 5 μm, more preferably 0. 0.01 to 1 μm. When the volume average particle diameter of the conductive agent is within this range, high conductivity can be obtained with a smaller amount of use. These conductive agents can be used alone or in combination of two or more. The amount of the conductive agent in the electrode composition layer 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. is there. When the amount of the conductive agent 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 a substance different from the polymer substance described later, and specifically has a solubility parameter of less than 12 (cal / cm ³ ) ^1/2 . The binder is not particularly limited as long as it is a compound capable of binding together an electrode active material, a conductive agent, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2. However, a dispersion type binder having a property of being dispersed in a solvent is preferable. The dispersion type binder is not particularly limited, but is preferably a fluorine-based polymer, a diene-based polymer, or an acrylate-based polymer, and the diene-based polymer or acrylate-based polymer can increase the withstand voltage, and is an electrochemical element. It is more preferable in that the energy density can be increased.

  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 mixture is usually 30% by weight or more, preferably 40% by weight or more, more preferably 50% by weight or more. Examples of the conjugated diene include butadiene and isoprene. 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). It is a polymer containing the monomer unit derived from a compound. 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 further increased. Can be small.

  The binder used in the present invention preferably has a polar group. When the binder has a polar group, the binding property between the current collector and the electrode composition layer can be further improved. The polar group means a functional group capable of dissociating in water or a functional group having polarization, and specifically includes an acid group, a nitrile group, an amide group, an amino group, a hydroxyl group, or an epoxy group. Among these, an acid group, a nitrile group, or an epoxy group is preferable, and an acid group or a nitrile group is particularly preferable in that the withstand voltage can be increased. The binder used in the present invention may have one type of the polar group, but preferably has two or more types. When the binder has two or more types of polar groups, the binding property between the current collector and the electrode composition layer can be further improved. Specific combinations in the case of having two types of polar groups include an acid group and a nitrile group, an acid group and an amide group, and an acid group and an amino group. The combination in the case of having three or more types of polar groups may be a combination of three types from the exemplified polar groups. The polar group in the binder can be formed by, for example, using a monomer having a polar group or a polymerization initiator having a polar group when polymerizing a polymer constituting the binder. It can be introduced into the coalescence.

  The content ratio of the polar group in the binder is the content ratio of the monomer having a polar group, preferably 0.1 to 40% by weight, more preferably 0.5 to 30% by weight, particularly preferably 1 to 1. 20% by weight. By setting the content ratio of the polar group in the binder within the above range, the binding property with the current collector is excellent, and the electrode strength of the electrode can be increased.

  Examples of the monomer containing a nitrile group as a polar group include acrylonitrile and methacrylonitrile, and acrylonitrile is preferable in that the withstand voltage can be increased.

  Monomers containing acid groups as polar groups include monobasic acid-containing monomers such as acrylic acid and methacrylic acid, and carboxylic acids such as dibasic acid-containing monomers such as maleic acid, fumaric acid, and itaconic acid. Monomer having a group; a monomer having a sulfonic acid group such as styrene sulfonic acid and methallyl sulfonic acid, and the like. Among them, a monomer having a carboxylic acid group is preferable, and the withstand voltage can be increased. Dibasic acid-containing monomers are particularly preferred.

  The shape of the binder used for the electrode for an electrochemical device of the present invention is not particularly limited, but the binding property to the current collector is good, and the capacity of the prepared electrode is deteriorated or deteriorated due to repeated charge and discharge. Therefore, it is preferable to be particulate. Examples of the particulate binder include those in which binder particles such as latex are dispersed in water, and powders obtained by drying such a dispersion.

  The glass transition temperature (Tg) of the binder used in the present invention is preferably 50 ° C. or lower, more preferably −40 to 0 ° C. When the glass transition temperature (Tg) of the binder is in this range, the binding property is excellent with a small amount of use, the binding property between the current collector and the electrode composition layer is excellent, the electrode strength is strong, and the flexibility The electrode density can be easily increased by a pressing process during electrode formation.

  The number average particle diameter when the binder used in the present invention is particulate is not particularly limited, but is usually 0.0001 to 100 μm, preferably 0.001 to 10 μm, more preferably 0.01 to 1 μm. When the number average particle diameter of the binder is within this range, an excellent binding force can be imparted to the electrode composition layer even when used in a small amount. Here, the number average particle diameter is a number average particle diameter calculated as an arithmetic average value obtained by measuring the diameter of 100 binder particles randomly selected in a transmission electron micrograph. The shape of the particles can be either spherical or irregular. These binders can be used alone or in combination of two or more. The content of the binder in the electrode composition layer 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. Range. When the content of the binder in the electrode composition layer is in the above range, sufficient adhesion between the obtained electrode composition layer and the current collector can be secured, the capacity of the electrochemical device is increased, and the internal resistance is decreased can do.

(Polymer substance)
In the present invention, a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 is used. The polymer substance is a substance different from the binder used in the present invention. A polymer substance having a solubility parameter in the above range has excellent affinity with an electrolyte solvent, and can easily swell and dissolve in the electrolyte solvent.
The solubility parameter is H. Although it can be determined by the method described in the edition of Immergut “Polymer Handbook” VII Solidity Parametic Values, pp 519-559 (John Wiley & Sons, 3rd edition, published in 1989), those which are not described in this publication can be obtained. It can be obtained according to the proposed “molecular attraction constant method”. In this method, the SP value (δ) is calculated from the characteristic value of the functional group (atomic group) constituting the compound molecule, that is, the statistics of the molecular attractive constant (G), the molecular weight (M), and the specific gravity (d) according to the following formula. It is a method to seek.
δ = ΣG / V = dΣG / M (V: specific volume, M: molecular weight, d: specific gravity)

In the present invention, when the solubility parameter of the polymer substance is less than 12 (cal / cm ³ ) ^1/2 , ion diffusion of the electrolytic solution is inhibited, the internal resistance is increased, and the electrode strength is remarkably reduced. On the other hand, when the solubility parameter exceeds 17 (cal / cm ³ ) ^1/2 , the internal resistance increases, the flexibility of the electrode composition layer decreases, and the electrode strength significantly decreases.

Examples of the polymer substance having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 include polymer compounds such as polyacrylonitrile, polyimide, polyamide, and polyurethane polymer. Among these, polymers having a nitrile group or an amide group such as polyacrylonitrile, polyimide, and polyamide are particularly excellent in affinity with an electrolytic solution, and can provide an electrode for an electrochemical device excellent in impregnation into the electrolytic solution. It is preferable.

The weight average molecular weight of the polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 used in the present invention is preferably 5,000 to 500,000, and 10,000 to 100,000. Is more preferable, it is more preferable that it is 10,000-100,000, and it is especially preferable that it is 15,000-50,000. When the weight average molecular weight of the polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 is in the above range, the polymer has excellent affinity with the electrolyte and easily dissolves in the electrolyte. The movement of the electrolyte solution in the composition layer can be facilitated, and the internal resistance of the electrochemical device can be further reduced. Here, the weight average molecular weight is a polystyrene equivalent value measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

The form of the polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 used in the present invention is not particularly limited, but is a dispersed type having a property of being dispersed in a solvent, that is, in the form of particles. It is preferable that the electrode composition layer be dispersed in water in view of easy drying of the electrode composition layer and excellent environmental load.

The number average particle diameter when the polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 used in the present invention is in the form of particles is preferably 0.001 to 1 μm. More preferably, it is 01-0.5 micrometer, and it is especially preferable that it is 0.05-0.1 micrometer. When the number average particle size of the polymer substance is in the above range, it has excellent affinity with the electrolytic solution, easily dissolves in the electrolytic solution, and facilitates the movement of the electrolytic solution in the electrode composition layer. It is excellent in that the internal resistance can be reduced. The number average particle diameter is a number average particle diameter calculated as an arithmetic average value obtained by measuring the diameters of 100 polymer particles randomly selected from a transmission electron micrograph.

In the present invention, the content of the polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 in the electrode composition layer is 0.1 to 20 parts by weight with respect to 100 parts by weight of the electrode active material, Preferably it is 0.5-10 weight part, Most preferably, it is 1-5 weight part. When the content of the polymer substance having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 in the electrode composition layer is in the above range, it has excellent affinity with the electrolyte and can be easily converted into the electrolyte. It can melt | dissolve and can move the electrolyte solution in an electrode composition layer easily, and can reduce the internal resistance of an electrochemical element more.

(Other ingredients)
The electrode composition layer used in the present invention includes an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 as essential components. May be included. Examples of other components include a conductive agent and a dispersant.

(Conductive agent)
Examples of the conductive agent used in the present invention include those composed of an allotrope of particulate carbon which has conductivity and does not have pores capable of forming an electric double layer. Specific examples include conductive carbon blacks such as furnace black, acetylene black, and ketjen black (registered trademark of Akzo Nobel Chemicals Bethloten Fennaut Shap). Among these, acetylene black and furnace black are preferable.

  The volume average particle diameter of the conductive agent used in the present invention is preferably smaller than the volume average particle diameter of the electrode active material, and the range thereof is usually 0.001 to 10 μm, preferably 0.05 to 5 μm, more preferably 0. 0.01 to 1 μm. When the volume average particle diameter of the conductive agent is within this range, high conductivity can be obtained with a smaller amount of use. These conductive agents can be used alone or in combination of two or more. The amount of the conductive agent in the electrode composition layer 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. is there. When the amount of the conductive agent 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.

(Dispersant)
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, oxidized starch, phosphate starch, casein, various modified starches, chitin, chitosan derivatives and the like. 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 in the electrode composition layer can be used as long as the effect of the present invention is not impaired, and is not particularly limited, but is usually 0.1 to 10 weights with respect to 100 parts by weight of the electrode active material. Parts, preferably 0.5 to 5 parts by weight, more preferably 0.8 to 2 parts by weight.

(Electrode composition layer)
In the present invention, an electrode composition layer comprising an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 is provided on the current collector. However, the formation method is not limited. Specifically, 1) an electrode composition obtained by kneading an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 is formed into a sheet. Then, a method of laminating the obtained sheet-shaped electrode composition on a current collector (kneading sheet forming method), 2) an electrode active material, a conductive agent, a binder, and a solubility parameter of 12 to 17 (cal / cm ³ ) A method of preparing a paste-like electrode composition containing a polymer material that is ^1/2 , applying this onto a current collector and drying it (wet molding method), 3) electrode active material, conductive Preparing a composite particle comprising an agent, a binder, and a polymer substance having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 , supplying this onto a current collector, forming a sheet, Examples include a method (dry molding method) obtained by roll pressing if necessary. That. Among these, 2) a wet molding method, 3) a dry molding method are preferable, and 3) an electrochemical element from which the dry molding method can be obtained has a higher capacity and is more preferable in that the internal resistance can be reduced.

In the present invention, the paste-like electrode composition used in the wet molding method includes an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 , In addition, the other components can be obtained by mixing, kneading and the like in a solvent. The dispersion medium is not particularly limited, but water is preferable in terms of environmental properties and drying equipment.

In the present invention, an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 constituting the paste electrode composition used in the wet molding method, As the apparatus used for mixing the other components, specifically, a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, a Hobart mixer, and the like can be used.

  In the present invention, the method for forming the electrode composition layer in the wet molding method is not particularly limited. For example, a method of forming the paste-like electrode composition on a current collector by a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, brushing, or the like can be given.

  In the present invention, the method for drying the paste-like electrode composition layer applied on the current collector by the wet molding method includes drying with hot air, hot air, low-humidity air, vacuum drying, (far) infrared rays, electron beams, etc. The drying method by irradiation is mentioned. Of these, a drying method using hot air and a drying method using irradiation with far infrared rays are preferable. The drying temperature and the drying time are preferably a temperature and a time at which the solvent in the paste-like electrode composition applied to the current collector can be completely removed, and the drying temperature is usually 50 to 300 ° C, preferably 80 to 250 ° C. The drying time is usually 2 hours or less, preferably 5 seconds to 30 minutes.

In the present invention, an electrode active material, a conductive agent, a binder, a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 used in the dry molding method, and the other components are included. The composite particle is a particle in which these plural materials are integrated. When the electrode composition is a composite particle, the electrode strength of the obtained electrode for an electrochemical device can be increased, and the internal resistance can be further reduced.

The composite particles suitably used in the present invention include an electrode active material, a conductive agent, a binder, and an essential component of the polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 and the other components. It is manufactured by granulating using arbitrary components such as.

  The granulation method of the composite particles is not particularly limited, and is spray drying granulation method, rolling bed granulation method, compression granulation method, stirring granulation method, extrusion granulation method, crushing granulation method, fluidized bed It can be produced by a known granulation method such as a granulation method, a fluidized bed multifunctional granulation method, a pulse combustion drying method, or a melt granulation method. Among these, the spray-drying granulation method is preferable because composite particles in which a binder and a conductive agent are unevenly distributed near the surface can be easily obtained. When composite particles obtained by the spray drying granulation method are used, the electrode of the present invention can be obtained with high productivity. In addition, the internal resistance of the electrode can be further reduced.

In the spray-drying granulation method, first, the electrode active material, the conductive agent, the binder, and the essential component of the polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 , Arbitrary components such as components are dispersed or dissolved in a solvent to obtain a slurry in which these components are dispersed or dissolved.

  The solvent used for obtaining the slurry is not particularly limited, but when using the above dispersant, 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 water and an organic solvent having a lower boiling point than 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.

An electrode active material, a conductive agent, a binder, and an essential component of a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 and an optional component such as the other component are dispersed in a solvent or The method or procedure for dissolving is not particularly limited, and examples thereof include an electrode active material, a conductive agent, a binder, a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 , a dispersant, and the like. A method of adding and mixing; after dissolving the dispersant in the solvent, the binder (for example, an aqueous dispersion of polymer particles) dispersed in the solvent and the solubility parameter of 12 to 17 (cal / cm ³ ) ^{1 / 2. A method} of adding and mixing a polymer material of ² , and finally adding and mixing an electrode active material and a conductive agent; a binder dispersed in a solvent and a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 polymer product is It was added an electrode active material and a conductive agent are mixed, the method and the like for mixing with the addition of dispersing agent dissolved in a solvent to the mixture. 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 10 to 3,000 mPa · s, preferably 30 to 1,500 mPa · s, more preferably 50 to 1,000 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 higher the viscosity of the slurry, the larger the spray droplets and the larger the weight 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 disc depends on the size of the disc, but is usually 5,000 to 40,000 rpm, preferably 15,000 to 40,000 rpm. The lower the rotational speed of the disk, the larger the spray droplets and the larger 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 consists of The slurry is introduced from the center of the spray platen, adheres to the spraying roller by centrifugal force, moves outside 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 is sprayed at the top of the drying tower and descends with the hot air, and the sprayed droplets 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 shape of the composite particles suitably used in the present invention is preferably substantially spherical. That is, the short axis diameter of the composite particles is L _s , the long axis diameter is L _l , L _a = (L _s + L _l ) / 2, and a value of (1− (L ₁ −L _s ) / L _a ) × 100 Is a sphericity (%), the sphericity is preferably 80% or more, more preferably 90% or more. Here, the minor axis diameter L _s and the major axis diameter L _l are values measured from a transmission electron micrograph image.

  The volume average particle diameter of the composite particles suitably used in the present invention is generally 10 to 100 μm, preferably 20 to 80 μm, more preferably 30 to 60 μm. The volume average particle diameter can be measured using a laser diffraction particle size distribution measuring apparatus.

  In the present invention, the feeder used in the step of supplying composite particles is not particularly limited, but is preferably a quantitative feeder capable of supplying composite particles quantitatively. Here, being able to supply quantitatively means that composite particles are continuously supplied using such a feeder, the supply amount is measured a plurality of times at regular intervals, and the average value m of the measured values and the standard deviation σm are obtained. It means that the CV value (= σm / m × 100) is 4 or less. The quantitative feeder preferably used in the present invention has a CV value of preferably 2 or less. Specific examples of the quantitative feeder include a gravity feeder such as a table feeder and a rotary feeder, and a mechanical force feeder such as a screw feeder and a belt feeder. Of these, the rotary feeder is preferred.

  Next, the current collector and the supplied composite particles are pressurized with a pair of rolls to form an electrode composition layer on the current collector. In this step, the composite particles heated as necessary are formed into a sheet-like electrode composition layer by a pair of rolls. The temperature of the supplied composite particles is preferably 40 to 160 ° C, more preferably 70 to 140 ° C. When composite particles in this temperature range are used, there is no slip of the composite particles on the surface of the press roll, and the composite particles are continuously and uniformly supplied to the press roll. An electrode composition layer with small variations can be obtained.

  The temperature at the time of molding is usually 0 to 200 ° C., preferably higher than the melting point or glass transition temperature of the binder, and more preferably 20 ° C. higher than the melting point or glass transition temperature. The forming speed in the case of using a roll is usually larger than 0.1 m / min, preferably 35 to 70 m / min. Moreover, the press linear pressure between the rolls for a press is 0.2-30 kN / cm normally, Preferably it is 0.5-10 kN / cm.

  In the above manufacturing method, the arrangement of the pair of 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 composite particles are supplied to at least one of the rolls so that the composite particles are supplied to the gap between the current collector and the rolls. The electrode composition layer can be formed by pressurization. When arranged substantially vertically, the current collector is transported in the horizontal direction, the composite particles are supplied onto the current collector, and the supplied composite particles are leveled with a blade or the like as necessary. It can supply between a pair of rolls and can form an electrode composition layer by pressurization.

  In order to eliminate variations in the thickness of the molded electrode composition layer, increase the density, and increase the capacity, post-pressurization may be further performed as necessary. The post-pressing method is generally a press process using a roll. In the roll press process, two cylindrical rolls are arranged in parallel at a narrow interval in the vertical direction, and each is rotated in the opposite direction. The roll may be temperature controlled, such as heated or cooled.

Although the density in particular of the electrode composition layer used for this invention is not restrict | limited, Usually, 0.30-10 g / cm < ³ >, Preferably it is 0.35-5.0 g / cm < ³ >, More preferably, it is 0.40-3. 0 g / cm ³ . The thickness of the electrode composition layer is not particularly limited, but is usually 5 to 1000 μm, preferably 20 to 500 μm, more preferably 30 to 300 μm.

(Current collector)
As a material for 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 a current collector such as a metal foil or a metal edge foil; a current collector having through-holes such as an expanded metal, a punching metal, or a net (hereinafter referred to as “perforated current collector”) May be described.).

  When a perforated current collector is used as the current collector, the ratio (opening ratio) of the holes through which the perforated current collector passes is 10 to 80 area%, preferably 20 to 60 area%, more preferably 30 to 30%. 50 area%. When the ratio of the through-holes of the perforated current collector is within this range, the diffusion resistance of the electrolytic solution is reduced, and the internal resistance of the electrochemical element is reduced.

  The thickness of the current collector used in the present invention is usually 5 to 100 μm, preferably 10 to 70 μm, and particularly preferably 20 to 50 μm.

The current collector used in the present invention preferably has a conductive adhesive layer. When the current collector has a conductive adhesive layer, the electron transfer resistance between the current collector and the electrode composition layer can be reduced, and the internal resistance of the electrochemical device can be further reduced.
The conductive adhesive suitably used in the present invention contains a conductive filler and a binder for conductive adhesive as essential components, and a dispersant and a surfactant as necessary.

(Conductive filler)
The conductive filler used in the present invention is not particularly limited as long as it is conductive particles, but is preferably electrochemically stable carbon particles. A carbon particle is a particle | grains which consist only of carbon or substantially only carbon. Specific examples of carbon particles include graphite having high conductivity due to the presence of delocalized π electrons (specifically, natural graphite, artificial graphite, etc.); Carbon black (specifically acetylene black, ketjen black, other furnace blacks, channel blacks, thermal lamp blacks, etc.), which is a spherical aggregate that forms the structure; carbon fibers and carbon whiskers, among these, Graphite or carbon black is particularly preferable in that the carbon particles of the conductive adhesive layer can be filled with high density, the electron transfer resistance can be reduced, and the internal resistance of the electrochemical element can be reduced.

(Binder for conductive adhesive)
The binder for conductive adhesive used in the present invention is not particularly limited as long as it is a compound capable of binding conductive fillers to each other. A suitable binder for conductive adhesive is a dispersion-type binder having a property of being dispersed in a solvent. Examples of the dispersion-type binder include polymer compounds such as fluorine-based polymers, diene-based polymers, acrylate-based polymers, polyimides, polyamides, polyurethane-based polymers, and fluorine-based polymers and diene-based polymers. Alternatively, an acrylate polymer is preferable, and a diene polymer or an acrylate polymer is more preferable in that the withstand voltage can be increased and the energy density of the electrochemical element can be increased.

  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 mixture 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). It is a polymer containing the monomer unit derived from a compound. 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.

  The glass transition temperature (Tg) of the binder for conductive adhesive used in the present invention is preferably 50 ° C. or lower, more preferably −40 to 0 ° C. When the glass transition temperature (Tg) of the binder for conductive adhesive is within this range, the binding property is excellent with a small amount of use, and the binding property between the current collector and the electrode composition layer is excellent. The strength is high and flexibility is high, and the electrode density can be easily increased by a pressing process at the time of electrode formation.

  When the binder for conductive adhesive used in the present invention is in the form of particles, the number average particle diameter is not particularly limited, but is usually 0.0001 to 100 μm, preferably 0.001 to 10 μm. More preferably, it is 0.01-1 micrometer. When the number average particle diameter is in this range when the binder is particulate, an excellent binding force can be imparted to the conductive adhesive layer even with a small amount of use. Here, the number average particle diameter is a number average particle diameter calculated as an arithmetic average value obtained by measuring the diameter of 100 binder particles randomly selected in a transmission electron micrograph. The shape of the particles can be either spherical or irregular. These binders can be used alone or in combination of two or more.

  In the present invention, the content of the binder in the conductive adhesive layer is usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, more preferably 100 parts by weight of the conductive filler. Is in the range of 1 to 10 parts by weight. When the amount of the binder for the conductive adhesive in the conductive adhesive layer is within this range, sufficient adhesion between the obtained electrode composition layer and the current collector can be ensured, and the capacity of the electrochemical device can be increased. In addition, the internal resistance can be lowered.

(Other ingredients)
The conductive adhesive layer used in the present invention contains a conductive filler and a binder for conductive adhesive as essential components, but preferably further contains a dispersant and / or a surfactant.

  The dispersant used in the present invention disperses a conductive adhesive composition comprising a conductive filler and a binder, and is not particularly limited, but is not limited to carboxymethyl cellulose acid, carboxymethyl cellulose ammonium, carboxymethyl cellulose alkali metal, carboxy Examples include methylcellulose alkaline earth metal. Among these, carboxymethyl cellulose ammonium and carboxymethyl cellulose alkali metal are preferable, and carboxymethyl cellulose ammonium is particularly preferable. In particular, when carboxymethyl cellulose ammonium is used, the conductive filler and the binder can be uniformly dispersed, the filling degree of the conductive filler in the conductive adhesive layer can be increased, and the electron transfer resistance can be reduced. The content of the dispersant in the conductive adhesive layer can be used within a range that does not impair the effects of the present invention, and is not particularly limited, but is preferably 0.1 to 100 parts by weight of the conductive filler. It is 20 parts by weight, more preferably 0.5 to 15 parts by weight, particularly preferably 0.8 to 10 parts by weight.

  The surfactant preferably used in the present invention uniformly disperses the conductive filler and the binder and lowers the surface tension of the current collector. Specifically, the alkyl sulfate ester salt and the alkylbenzene sulfonate salt are used. , Fatty acid salts, anionic surfactants such as naphthalenesulfonic acid formalin condensates; nonionic surfactants such as polyoxyethylene aralkyl ethers and glycerin fatty acid esters; cationic interfaces such as alkylamine salts and quaternary ammonium salts Activators; amphoteric surfactants such as alkylamine oxides and alkylbetaines are listed. Among these, anionic surfactants and nonionic surfactants are preferable, and anionic surfactants are particularly preferable from the viewpoint of excellent durability of the electrochemical device. The content of the surfactant in the conductive adhesive layer is preferably 0.5 to 20 parts by weight, more preferably 1.0 to 15 parts by weight, and particularly preferably 2.10 parts by weight with respect to 100 parts by weight of the conductive filler. It is in the range of 0 to 10 parts by weight.

  The conductive adhesive layer used in the present invention is obtained by mixing, kneading, etc., a conductive filler, a binder for conductive adhesive, and, if necessary, a dispersant or a surfactant in a solvent (dispersion medium). The conductive adhesive composition obtained by the above can be formed on a current collector and dried. Although it does not restrict | limit especially as said solvent, Water is preferable at the point of environmental property and drying equipment.

  Specific examples of the apparatus used to obtain the conductive adhesive layer composition used in the present invention include a ball mill, a sand mill, a pigment disperser, a crusher, an ultrasonic disperser, a homogenizer, a planetary mixer, and a Hobart mixer. Etc. can be used.

  The method for forming the conductive adhesive layer used in the present invention is not particularly limited. For example, the conductive adhesive layer composition is formed on the current collector by a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, brushing, or the like.

  The solid content concentration of the conductive adhesive layer composition used in the present invention is usually 10 to 60% by weight, preferably 15 to 50% by weight, particularly preferably 20 to 40% by weight, although it depends on the coating method. When the solid content concentration is in this range, the resulting conductive adhesive layer is highly filled, and the energy density and output density of the electrochemical device are increased.

  The viscosity of the conductive adhesive layer composition used in the present invention is usually 50 to 10,000 mPa · s, preferably 100 to 5,000 mPa · s, particularly preferably 200 to 2,000 mPa · s, although it depends on the coating method. s. When the viscosity of the conductive adhesive composition is within this range, a uniform conductive adhesive layer can be formed on the current collector.

  Examples of the method for drying the conductive adhesive layer include drying by warm air, hot air, low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams. Of these, a drying method using hot air and a drying method using irradiation with far infrared rays are preferable. The drying temperature and the drying time are preferably a temperature and a time at which the solvent in the slurry-like conductive adhesive layer composition applied to the current collector can be completely removed, and the drying temperature is usually 50 to 300 ° C., preferably 80 to The drying time is usually 2 hours or less, preferably 5 seconds to 30 minutes.

  The thickness of the conductive adhesive layer is usually 0.01 to 20 μm, preferably 0.1 to 15 μm, particularly preferably 1 to 10 μm. When the thickness of the conductive adhesive layer is in the above range, good adhesiveness can be obtained and the electron transfer resistance can be reduced.

(Electrochemical element)
The electrochemical element of this invention has the said electrode for electrochemical elements.
Examples of the electrochemical element include lead storage batteries, alkaline batteries, lithium ion secondary batteries, electric storage devices such as electric double layer capacitors and lithium ion capacitors, lithium ion secondary batteries having excellent energy density and output density, electric double layers Capacitors and lithium ion capacitors are preferred.
Examples of components other than the electrode for an electrochemical element include a separator and an electrolytic solution.

(Separator)
A separator will not be specifically limited if it can insulate between the electrodes for electrochemical elements, and can pass a cation and an anion. Specifically, polyolefins such as polyethylene and polypropylene, aromatic polyamides, microporous membranes or nonwoven fabrics made of rayon or glass fiber; porous membranes generally made of pulp called electrolytic capacitor paper; porous containing inorganic ceramic powder A quality resin coat or the like can be used. A separator is arrange | positioned between the electrodes for electrochemical elements so that said pair of electrode composition layer may oppose, and an element is obtained. Although the thickness of a separator is suitably selected according to a use purpose, it is 1-100 micrometers normally, Preferably it is 10-80 micrometers, More preferably, it is 20-60 micrometers.

(Electrolyte)
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

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 ˜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. Specifically, carbonates such as propylene car boat, ethylene carbonate and butylene 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 device can be manufactured by winding, laminating or folding the device into a container as necessary, and pouring the electrolyte into the container and sealing it. In addition, an element obtained by impregnating the element with the electrolytic solution in advance 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. Each characteristic in an Example and a comparative example is measured in accordance with the following method.

(Calculation method of solubility parameter of polymer substance and binder)
Solubility parameters for polymeric substances and binders are described in E. H. It is obtained by the method described in “Polymer Hundbook” edited by Immergut VII Solidity Parametic Values, pp 519-559 (John Wiley & Sons, 3rd edition, 1989). Those not described in this publication are determined according to the “molecular traction constant method” proposed by Small. This method is a method for obtaining the SP value (δ) according to the following equation from the characteristic value of the functional group (atomic group) constituting the compound molecule, that is, the statistics of the molecular attractive constant (G) and the molecular weight.
SP value of polymer substance δ = ΣG / V = dΣG / M (V: specific volume, M: molecular weight, d: specific gravity)

(Weight average molecular weight of polymer material)
The polymer material is formed into a film, dried and cut out. And the cut | disconnected polymer substance film is melt | dissolved using tetrahydrofuran, and it measures by a gel permeation chromatography (GPC). In addition, let a weight average molecular weight be a polystyrene conversion value.

(Elution amount of polymer substance to electrolyte)
The polymer material is formed into a film, dried, and cut to a weight M1. The polymer material film cut out is immersed in an electrolytic solution in which tetraethylammonium fluoroborate is dissolved at a concentration of 1.0 mol / liter using propylene carbonate as a solvent, and stored at 70 ° C. for 72 hours. After vacuum drying at 70 ° C. for 24 hours, the weight M2 of the polymer film is measured again. The elution degree (%) (= (M1−M2) / M1 × 100) is calculated from the measured weights M1 and M2 of the polymer substance film. As the elution degree is larger, a larger number of void structures can be formed in the electrode composition layer, which indicates better internal resistance.

(Electrolytic solution impregnation)
The electrolyte impregnation property of the electrode for an electrochemical element is obtained by dissolving an electrolyte obtained by dissolving tetraethylammonium fluoroborate at a concentration of 1.0 mol / liter using propylene carbonate as a solvent in an electrode for an electrochemical element cut out to 5 cm × 5 cm. It is performed by dropping 20 μL and measuring the time until the electrolyte droplet disappears from the electrode surface. It shows that an electrode is excellent in electrolyte solution permeability, so that this time is short.

(Electrode flexibility)
The flexibility of the electrode for an electrochemical element is obtained by winding the electrode for an electrochemical element cut out to 1 cm × 8 cm around a metal rod having a diameter of 1 mm and a metal rod having a diameter of 2 mm, and evaluating the resulting crack as follows. The smaller the number of cracks, the better the flexibility, that is, the better the electrode strength.
○: No crack even with a metal rod with a diameter of 1 mm or a metal rod with a diameter of 2 mm. Δ: There is no crack with a metal rod with a diameter of 2 mm, but there is a crack with a metal rod with a diameter of 1 mm. Is

(Capacitance and internal resistance of electric double layer capacitor)
An electric double layer capacitor of a laminated laminate cell is prepared using an electrode for an electric double layer capacitor, allowed to stand for 24 hours, and then charged and discharged to measure capacitance and internal resistance. Here, charging starts at a constant current of 2 A, and when the voltage reaches 2.7 V, the voltage is maintained for 1 hour to be constant voltage charging. Discharging is performed immediately after the end of charging until it reaches 0 V at a constant current of 2 A. The capacitance is calculated from an energy conversion method using discharge energy, and the internal resistance is calculated from a voltage drop immediately after discharge. The capacitance is expressed as a capacitance (F / g) per electrode unit weight.

(Floating characteristics of electric double layer capacitor)
About the electric double layer capacitor of the laminated laminate cell whose capacitance and internal resistance were measured, it was held at 2.7 V for 1000 hours (floating) in a 70 ° C. environment (floating) and then discharged until reaching 0 V at a constant current of 2 A. Do. Then, the capacitance and internal resistance after floating are calculated by the above calculation method, and the capacitance retention ratio (= the capacitance after floating) is calculated from the change from the capacitance before floating (the capacitance calculated above). (Capacitance / capacitance before floating) and resistance change rate (= internal resistance after floating / internal resistance before floating) are calculated and evaluated. It shows that it is excellent in durability, so that a capacity | capacitance maintenance factor is high and a resistance maintenance factor is low.

Example 1
As an electrode active material, 100 parts of activated carbon powder having a volume average particle size of 17 μm, which is a water vapor activated activated carbon made from coconut shell (Shirakaba PC; manufactured by Nippon Enviro Chemicals), 1.5% aqueous solution of carboxymethyl cellulose (DN) as a dispersant -800H; manufactured by Daicel Chemical Industries, Ltd.) in an amount equivalent to a solid content of 2.0 parts, acetylene black (denka black powder form: manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive material, and number average particle size of 0 as a binder. .25 μm acrylate polymer (copolymer obtained by emulsion polymerization of 76 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile and 4 parts of itaconic acid: solubility parameter: 10.8 (cal / cm ³ ) ^1/2 ) A 40% aqueous dispersion of 3.0 parts by weight in terms of solid content, a nitrile group as a polymer substance, and a weight average molecular weight of 354,0 0, the number average particle size of 0.17 .mu.m, a solubility parameter of ^{12.77 (cal / cm 3) 1/2} , the elution of 47% of the polymer (2-ethylhexyl 30 parts of acrylic acid to the electrolytic solution, acrylonitrile 70 A 40% aqueous dispersion of a copolymer obtained by emulsion polymerization of a part) and an ion composition of 2.0% in terms of solid content and ion-exchanged water so that the total solid concentration is 35%. A slurry for physical layer was prepared.

  The electrode composition layer slurry is applied on one side of an aluminum current collector having a thickness of 30 μm by a doctor blade at an electrode forming speed of 20 m / min, and dried at 60 ° C. for 5 minutes and then at 120 ° C. for 5 minutes. After that, it was punched out to a square of 5 cm to obtain an electrode for an electric double layer capacitor (electrode for an electrochemical element) having an electrode composition layer having a thickness of 100 μm. The impregnation property and flexibility of the electrolytic double layer capacitor electrode were measured. The results are shown in Table 1.

  Cellulose (TF40; manufactured by Nippon Kogyo Kogyo Co., Ltd.) is used as an electrode for the electric double layer capacitor and a separator, and the electrolytic solution is impregnated at room temperature for 1 hour, and then an electrode composition layer of two electric double layer capacitor electrodes A laminated cell-shaped electric double layer capacitor (electrochemical element) is made by facing each other so that the electrode faces the inside through the separator and the electric double layer capacitor electrodes are not in electrical contact with each other. did. As the electrolytic solution, a solution in which tetraethylammonium fluoroborate was dissolved at a concentration of 1.0 mol / liter using propylene carbonate as a solvent was used. The capacitance, internal resistance, and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

(Example 2)
It has a nitrile group as a polymer substance, has a weight average molecular weight of 338,000, a number average particle diameter of 0.17 μm, a solubility parameter of 14.39 (cal / cm ³ ) ^1/2 , and an elution degree to an electrolyte solution Except for using 2.0 parts of a 40% aqueous dispersion of 78% polymer (a polymer obtained by emulsion polymerization of 100 parts of acrylonitrile) in a solid content equivalent amount, the same as in Example 1, An electrode for an electric double layer capacitor and an electric double layer capacitor were produced. The electrolytic solution impregnation and flexibility of the electric double layer capacitor electrode, and the capacitance, internal resistance and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

(Example 3)
It has a nitrile group as a polymer substance, has a weight average molecular weight of 100,000, a number average particle size of 0.15 μm, a solubility parameter of 14.39 (cal / cm ³ ) ^1/2 , and an elution degree to an electrolytic solution. Except for using 2.0 parts of a 40% aqueous dispersion of an 85% polymer (a polymer obtained by emulsion polymerization of 100 parts of acrylonitrile) in an amount equivalent to a solid content, An electrode for an electric double layer capacitor and an electric double layer capacitor were produced. The electrolytic solution impregnation and flexibility of the electric double layer capacitor electrode, and the capacitance, internal resistance and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

Example 4
It has a nitrile group as a polymer substance, has a weight average molecular weight of 23,000, a number average particle size of 0.13 μm, a solubility parameter of 14.39 (cal / cm ³ ) ^1/2 , and an elution degree to an electrolytic solution. Except that a 40% aqueous dispersion of a 91% polymer (a polymer obtained by emulsion polymerization of 100 parts of acrylonitrile) was used in an amount equivalent to a solid content of 2.0 parts, the same as in Example 1, An electrode for an electric double layer capacitor and an electric double layer capacitor were produced. The electrolytic solution impregnation and flexibility of the electric double layer capacitor electrode, and the capacitance, internal resistance and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

(Example 5)
It has a nitrile group as a polymer substance, has a weight average molecular weight of 23,000, a number average particle diameter of 0.05 μm, a solubility parameter of 14.39 (cal / cm ³ ) ^1/2 , and an elution degree to an electrolytic solution. Except that a 40% aqueous dispersion of a 95% polymer (a polymer obtained by emulsion polymerization of 100 parts of acrylonitrile) was used in an amount equivalent to a solid content of 2.0 parts, the same as in Example 1, An electrode for an electric double layer capacitor and an electric double layer capacitor were produced. The electrolytic solution impregnation and flexibility of the electric double layer capacitor electrode, and the capacitance, internal resistance and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

(Example 6)
As an electrode active material, 100 parts of activated carbon powder having a volume average particle size of 17 μm, which is a water vapor activated activated carbon made from coconut shell (Shirakaba PC; manufactured by Nippon Enviro Chemicals), 1.5% aqueous solution of carboxymethyl cellulose (DN) as a dispersant -800H; manufactured by Daicel Chemical Industries, Ltd.) in an amount equivalent to a solid content of 2.0 parts, acetylene black (denka black powder form: manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive material, and number average particle size of 0 as a binder. .25 μm acrylate polymer (copolymer obtained by emulsion polymerization of 76 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile and 4 parts of itaconic acid: solubility parameter: 10.8 (cal / cm ³ ) ^1/2 ) A 40% aqueous dispersion of 3.0 parts by weight in terms of solid content, a nitrile group as a polymer substance, and a weight average molecular weight of 23,000 Heavy number-average particle diameter of 0.05 .mu.m, a solubility parameter of ^{14.39 (cal / cm 3) 1/2} , the elution of the electrolytic solution is obtained by emulsion polymerization of 95% of the polymer (100 parts of acrylonitrile The electrode composition layer slurry was prepared by mixing 2.0 parts of a 40% aqueous dispersion of the coalescence) in an amount corresponding to the solid content and ion-exchanged water so that the total solid content concentration was 30%.

  On the other hand, as a conductive filler, 80 parts of spherical graphite (JB-5; manufactured by Nippon Graphite Industry Co., Ltd.) and 20 parts of carbon black (BMAB; manufactured by Denki Kagaku Kogyo Co., Ltd.) and 4.0% aqueous solution of carboxymethyl cellulose ammonium as a dispersant ( DN-10L (manufactured by Daicel Chemical Industries, Ltd.) in an amount corresponding to a solid content of 4 parts, and an acrylate polymer (acrylic acid 2-containing a carboxylic acid group and a nitrile group having a number average particle size of 0.25 μm as a binder. A copolymer obtained by emulsion polymerization of 76% by weight of ethylhexyl, 20% by weight of acrylonitrile, and 4% by weight of itaconic acid) is 8 parts in a solid equivalent amount, and ion exchange water has a total solids concentration of 35%. It mixed so that the conductive adhesive composition might be prepared.

  The conductive adhesive composition is discharged from a pair of dies so as to sandwich an aluminum current collector with a thickness of 30 μm, and applied to one side of the current collector at a molding speed of 30 m / min. Drying for 4 minutes formed a 4 μm thick conductive adhesive layer.

  On one side of the aluminum current collector on which the conductive adhesive is formed, the electrode composition layer slurry is applied by a doctor blade at an electrode forming speed of 20 m / min, at 60 ° C. for 5 minutes, and then at 120 ° C. After being dried for 5 minutes, an electrode for an electric double layer capacitor having an electrode composition layer having a thickness of 100 μm was obtained by punching out in a square of 5 cm. Table 1 shows the measurement results of the electrolyte impregnation property and flexibility of the electric double layer capacitor electrode.

  A laminated cell-shaped electric double layer capacitor was produced in the same manner as in Example 1 except that the electrode for electric double layer capacitor was used as the electrode for electric double layer capacitor. Table 1 shows the measurement results of capacitance, internal resistance, and floating characteristics of this electric double layer capacitor.

(Example 7)
As an electrode active material, 100 parts of activated carbon powder having a volume average particle size of 17 μm, which is a water vapor activated activated carbon made from coconut shell (Shirakaba PC; manufactured by Nippon Enviro Chemicals), 1.5% aqueous solution of carboxymethyl cellulose (DN) as a dispersant -800H; manufactured by Daicel Chemical Industries, Ltd.) in an amount equivalent to a solid content of 2.0 parts, 5 parts of acetylene black (denka black powder; manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive agent, and a number average particle size of 0 as a binder. .25 μm acrylate polymer (copolymer obtained by emulsion polymerization of 76 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile and 4 parts of itaconic acid: solubility parameter: 10.8 (cal / cm ³ ) ^1/2 ) A 40% aqueous dispersion of 3.0 parts by weight in terms of solid content, a nitrile group as a polymer substance, and a weight average molecular weight of 23,000 Heavy number-average particle diameter of 0.05 .mu.m, a solubility parameter of ^{14.39 (cal / cm 3) 1/2} , the elution of the electrolytic solution is obtained by emulsion polymerization of 95% of the polymer (100 parts of acrylonitrile The electrode composition layer slurry was prepared by mixing 2.0 parts of a 40% aqueous dispersion of the coalescence) in an amount corresponding to the solid content and ion-exchanged water so that the total solid content concentration was 20%.

  Next, the slurry was sprayed using a spray dryer (OC-16; manufactured by Okawara Kako Co., Ltd.). The rotating disk type atomizer (diameter 65 mm) had a rotational speed of 25,000 rpm, a hot air temperature of 150 ° C., and a particle recovery outlet temperature. Spray drying granulation was performed under the condition of 90 ° C. to obtain spherical composite particles for electrode composition layer (electrode composition) having a volume average particle diameter of 56 μm and a sphericity of 93%.

  The conductive particles obtained in Example 6 were applied to the above composite particles in a roll (rolling rough surface heat roll; manufactured by Hirano Giken Co., Ltd.) (roll temperature 100 ° C., press linear pressure 3.9 kN / cm). A sheet-like electrode composition layer is formed on a conductive adhesive layer at a forming speed of 20 m / min, and is punched out in a square of 5 cm. An electrode for an electric double layer capacitor having an electrode composition layer of 100 μm was obtained. The impregnation property and flexibility of the electrolytic double layer capacitor electrode were measured. The results are shown in Table 1.

  A laminated cell-shaped electric double layer capacitor was produced in the same manner as in Example 1 except that the electrode for electric double layer capacitor was used as the electrode for electric double layer capacitor. The capacitance, internal resistance, and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

(Comparative Example 1)
As a high molecular weight material, the weight average molecular weight is 689,000, the number average particle diameter is 0.25 μm, the solubility parameter is 9.93 (cal / cm ³ ) ^1/2 , and the elution degree to the electrolytic solution is 5.5%. Except for using 40 parts of a 40% aqueous dispersion of a polymer (copolymer obtained by emulsion polymerization of 100 parts of methyl methacrylate) in an amount equivalent to the solid content, in the same manner as in Example 1, An electrode for an electric double layer capacitor and an electric double layer capacitor were produced. The electrolytic solution impregnation and flexibility of the electric double layer capacitor electrode, and the capacitance, internal resistance and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

(Comparative Example 2)
As a polymer substance, a polymer having a weight average molecular weight of 587,000, a number average particle diameter of 0.25 μm, a solubility parameter of 19.19 (cal / cm ³ ) ^1/2 , and an elution degree of 98% in an electrolytic solution For electric double layer capacitors, as in Example 1, except that a 40% aqueous dispersion of (polymer obtained by emulsion polymerization of 100 parts of methacrylamide) was used in an amount of 2.0 parts in terms of solid content. An electrode and an electric double layer capacitor were produced. The electrolytic solution impregnation and flexibility of the electric double layer capacitor electrode, and the capacitance, internal resistance and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

(Comparative Example 3)
An electrode for an electric double layer capacitor and an electric double layer capacitor were produced in the same manner as in Example 7 except that no polymer substance was used. The electrolytic solution impregnation and flexibility of the electric double layer capacitor electrode, and the capacitance, internal resistance and floating characteristics of the electric double layer capacitor were measured. The results are shown in Table 1.

(Table 1)

(Capacity characteristics and rate characteristics of lithium ion secondary batteries)
A lithium ion secondary battery in the form of a laminated laminate cell is allowed to stand for 24 hours, and then a charge / discharge operation is performed to measure capacity and rate characteristics. Here, charging starts at a constant current of 0.1 C, and when the voltage reaches 4.2 V, the voltage is maintained for 1 hour to be constant voltage charging. Further, immediately after the end of charging, discharging is performed until the voltage reaches 3 V with a constant current of 0.1 C, and a current capacity value is calculated to be a capacity C0. As for the rate characteristic, a current capacity value when the discharge current value is 10 C is calculated and set as a capacity C1, and the capacity retention ratio ΔC rate (%) = C1 / C0 × 100 is evaluated as the rate characteristic. The larger the ΔC rate value, the better the rate characteristics, that is, the lower the internal resistance and the higher the output density.

(Cycle characteristics of lithium ion secondary battery)
A charge / discharge cycle is performed in which a lithium ion secondary battery in the form of a laminated laminate cell is charged with a constant current of 1 C up to a voltage of 4.2 V and discharged with a constant current of 1 C up to a voltage of 3 V. The charge / discharge cycle is performed up to 50 cycles, the capacity C3 of the 50th cycle with respect to the initial capacity C2, and the capacity retention ratio ΔC cycle (%) = C3 / C2 × 100 is evaluated as the cycle characteristics. It shows that it is excellent in cycling characteristics, ie, durability, so that the value of (DELTA) C cycle is large.

(Example 8)
As an electrode active material of the positive electrode, 100 parts of lithium cobaltate (C10N, manufactured by Cellseed Co., Ltd.), and 1.5% aqueous solution of carboxymethylcellulose (BSH-12, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a dispersant is equivalent to 1 in solid content. 0.0 part, 5 parts of acetylene black (DENKA BLACK, manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive agent, and acrylate polymer having a number average particle size of 0.25 μm as a binder (76 parts of 2-ethylhexyl acrylate, 20 parts of acrylonitrile) , A copolymer obtained by emulsion polymerization of 4 parts of itaconic acid: a solubility parameter: 10.8 (cal / cm ³ ) ^1/2 ) 40% aqueous dispersion of 1.0 part in terms of solid content, high It has a nitrile group as a molecular substance, has a weight average molecular weight of 23,000, a number average particle diameter of 0.05 μm, and a solubility parameter of 14.39 (cal / cm ³ ). ^1/2 , 2.0 parts of a 40% aqueous dispersion of a polymer (polymer obtained by emulsion polymerization of 100 parts of acrylonitrile) having an elution degree of 95% in an electrolyte solution, and an ion exchange amount Water was mixed so that the total solid content concentration was 50% to prepare a slurry for an electrode composition layer.

  The positive electrode composition layer slurry is applied onto an aluminum current collector having a thickness of 30 μm by a doctor blade at an electrode forming speed of 20 m / min, and dried at 60 ° C. for 5 minutes and then at 120 ° C. for 5 minutes. After that, it was punched out to 5 cm square to obtain a positive electrode for lithium ion secondary battery (electrode for electrochemical device) having an electrode composition layer having a thickness of 100 μm. The impregnation property and flexibility of the electrolyte for the positive electrode for lithium ion secondary battery were measured. The results are shown in Table 2.

  On the other hand, as an electrode active material for the negative electrode, 100 parts of natural graphite (KS-6, manufactured by Timcal) and a 1.5% aqueous solution of carboxymethylcellulose (BSH-12, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as the dispersant correspond to the solid content. 40 parts of a diene polymer (copolymer obtained by emulsion polymerization of 65 parts of styrene, 30 parts of butadiene, and 5 parts of itaconic acid) having an amount of 1.0 part and a number average particle size of 0.1 μm as a binder. A slurry for an electrode composition layer was prepared by mixing 1.0 part of a% aqueous dispersion in an amount corresponding to a solid content and ion-exchanged water so that the total solid concentration was 50%.

  The negative electrode composition layer slurry was applied onto a 20 μm thick copper current collector by a doctor blade at an electrode forming speed of 20 m / min, first at 60 ° C. for 5 minutes, and then at 120 ° C. for 5 minutes. After drying, it was punched out in a square of 5 cm to obtain a negative electrode for a lithium ion secondary battery having an electrode composition layer having a thickness of 80 μm.

This positive electrode and negative electrode for lithium ion secondary batteries and a separator made of polypropylene as a separator are impregnated with an electrolyte at room temperature for 1 hour, and then an electrode composition layer for positive electrode and negative electrode for lithium ion secondary batteries Is placed so as to face the inside through the separator, and the electrodes for the lithium ion secondary battery are arranged so as not to be in electrical contact with each other, so that the laminated cell-shaped lithium ion secondary battery (electrochemical element) Was made. As an electrolytic solution, a solvent in which ethylene carbonate and diethyl carbonate were dissolved in a volume ratio of 1: 1 and LiPF ₆ was dissolved at a concentration of 1.0 mol / liter was used. About this lithium ion secondary battery, the capacity | capacitance characteristic, the rate characteristic, and the cycle characteristic were measured. The results are shown in Table 2.

(Comparative Example 4)
A lithium ion secondary battery electrode and a lithium ion secondary battery were produced in the same manner as in Example 8 except that no polymer substance was used. The electrolyte solution impregnation and flexibility of this lithium ion secondary battery electrode (positive electrode) and the capacity characteristics, rate characteristics, and cycle characteristics of the lithium ion secondary battery were measured. The results are shown in Table 2.

(Table 2)

As is clear from the results of the above Examples and Comparative Examples, when the electrode for an electrochemical device of the present invention is used, the impregnation into the electrolyte solution is excellent, the electrode strength is improved, the electrode density is improved, that is, the energy density is increased. It becomes high, it becomes possible to reduce internal resistance and to improve durability.
On the other hand, when a polymer material having a solubility parameter of less than 12 (cal / cm ³ ) ^1/2 or more than 17 (cal / cm ³ ) ^1/2 is used (Comparative Example 1, Comparative Example 2) In the case where a polymer substance having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 is not used (Comparative Examples 3 and 4), the impregnation property to the electrolytic solution and the electrode strength are reduced. Internal resistance increases and durability is inferior.

Claims (9)

An electrode composition layer containing an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 is formed on the current collector. Electrode for electrodes. The electrode for an electrochemical element according to claim 1, wherein the polymer substance has a weight average molecular weight of 5,000 to 500,000. The electrode for an electrochemical element according to claim 1, wherein the polymer substance is in the form of particles. The electrode for an electrochemical element according to claim 3, wherein the polymer substance has a number average particle diameter of 0.001 to 1 μm. The electrode for an electrochemical element according to any one of claims 1 to 4, wherein the polymer substance has a nitrile group. 6. The electrode for an electrochemical element according to claim 1, wherein the content of the polymer substance is 0.1 to 20 parts by weight with respect to 100 parts by weight of the electrode active material. The electrode composition layer is composed of composite particles containing an electrode active material, a conductive agent, a binder, and a polymer material having a solubility parameter of 12 to 17 (cal / cm ³ ) ^1/2 . The electrode for electrochemical elements in any one. The electrode for an electrochemical element according to claim 1, wherein the current collector has a conductive adhesive layer. The electrochemical element which has an electrode for electrochemical elements in any one of Claims 1-8.