JP5195117B2 - Electrode for electric double layer capacitor and electric double layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric double layer capacitor capable of suppressing the degradation of an electrolyte, increasing an operation voltage and improving a floating characteristic. <P>SOLUTION: An electrode for the electric double layer capacitor is obtained by forming an electrode composition layer including an electrode activation substance, a conductive material, a binder, and a polydibasic acid on a current collector and the electrode for the electric double layer capacitor is used for the electric double layer capacitor. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electrode for an electric double layer capacitor and an electric double layer capacitor. More specifically, the present invention relates to an electrode for an electric double layer capacitor that suppresses decomposition of an electrolytic solution and has excellent floating characteristics, and an electric double layer capacitor using the same.

  An electric double layer capacitor is a device that can be rapidly charged and discharged with a large current, has little loss during charging and discharging, and has a remarkably long cycle life, and is suitable for energy saving. Recently, large products have been developed and are expected to be used as secondary power sources for electric vehicles, hybrid vehicles, and fuel cell vehicles.

  The electric double layer capacitor is characterized by high output density, and by using an organic electrolyte, the operating voltage can be increased and the energy density can be increased. Electrolyte using propylene carbonate as a typical solvent for organic electrolytes has the characteristics of low viscosity, high electrical conductivity, and low internal resistance. However, since the withstand voltage is low, the operating voltage can be increased. There was a problem of difficulty.

In order to increase the operating voltage, it has been proposed to add organic polyphosphoric acid (Patent Document 1). In detail, the electric double layer capacitor that has been constructed uses an electrode composition layer made of activated carbon powder as an electrode active material, carbon black as a conductive material, and polytetrafluoroethylene as a binder, and a phosphate compound as an electrolyte solvent. It consisted of propylene carbonate with added. However, in this method, the improvement effect was unclear at an operating voltage of 2.5 V or higher.
JP 2007-227732 A

Similarly, it has been proposed to add polyacrylic acid (Patent Document 2). In detail, the constructed electric double layer capacitor uses an electrode composition layer made of activated carbon powder as an electrode active material, carbon black as a conductive material, and polyacrylic acid as a binder. However, even in this method, the improvement effect was unclear at an operating voltage of 2.5 V or higher.
Japanese Patent Laid-Open No. 2005-136397

  An object of the present invention is to provide an electric double layer capacitor that can suppress decomposition of an electrolyte, increase an operating voltage, and improve floating characteristics.

  As a result of intensive studies to achieve the above object, the inventor of the present invention has found that the electrode for an electric double layer capacitor of the present invention has added a polydibasic acid to an electrode composition comprising an electrode active material, a conductive material and a binder. In addition, it has been found that even when the operating voltage is increased to 2.5 V or more by forming an electrode composition layer on the current collector, decomposition of the electrolyte is suppressed and floating characteristics are improved.

  The present invention has been completed based on these findings.

  Thus, according to the present invention, there is provided an electrode for an electric double layer capacitor in which an electrode composition layer comprising an electrode active material, a conductive material, a binder and a polydibasic acid is formed on a current collector. The

  According to the present invention, there is provided an electric double layer capacitor using the electric double layer capacitor electrode.

  By using the electric double layer capacitor electrode of the present invention, an electric double layer capacitor having excellent floating characteristics can be easily produced. In addition, since the electric double layer capacitor of the present invention is excellent in floating characteristics, it is used as a backup power source for a memory of a personal computer or a portable terminal, a power source for instantaneous power failure such as a personal computer, application to an electric vehicle or a hybrid vehicle, combined use with a solar cell. The solar power generation energy storage system, a load leveling power source combined with a battery, and the like can be suitably used.

  The electrode for an electric double layer capacitor of the present invention is characterized in that an electrode composition layer comprising an electrode active material, a conductive material, a binder and a polydibasic acid is formed on a current collector.

(Electrode active material)
As the electrode active material used for the electric double layer capacitor electrode of the present invention, an allotrope of carbon 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 of the present invention is usually 0.1 to 100 μm, preferably 1 to 50 μm, and more preferably 5 to 20 μm. When the volume average particle diameter of the electrode active material is within this range, the obtained electrode composition layer is densified, the capacity of the electric double layer capacitor can be increased, and the internal resistance can be decreased.

The specific surface area of the electrode active material used in the electric double layer capacitor electrode of the present invention, ^{30 m} 2 / g or more, preferably 500~5,000m ² / g, more preferably 1,000~3,000m ² / g Preferably there is. When the specific surface area of the electrode active material is within this range, the capacity per weight and the capacity per volume of the electric double layer capacitor can be increased and the internal resistance can be decreased. These electrode active materials can be used alone or in combination of two or more.

(Conductive material)
The conductive material used for the electrode for the electric double layer capacitor of the present invention is composed of an allotrope of particulate carbon that has conductivity and does not have pores that can form an electric double layer. , Acetylene black, and ketjen black (registered trademark of Akzo Nobel Chemicals Bethloten Fennaut Shap); graphite such as natural graphite and artificial graphite. Among these, conductive carbon black is preferable, and acetylene black and furnace black are more preferable.

  The volume average particle diameter of the conductive material used for the electrode for the electric double layer capacitor of the present invention is preferably smaller than the volume average particle diameter of the electrode active material, and the range is usually 0.001 to 10 μm, preferably 0.05. It is -5 micrometers, More preferably, it is 0.01-1 micrometer. When the volume average particle diameter of the conductive material is within this range, high conductivity can be obtained with a smaller amount of use. These conductive materials can be used alone or in combination of two or more. The amount of the conductive material is usually 0.1 to 50 parts by weight, preferably 0.5 to 15 parts by weight, and more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. When the amount of the conductive material is within this range, the capacitance of the electric double layer capacitor using the obtained polarizable electrode can be increased and the internal resistance can be decreased.

(Binder)
The binder used for the electrode for the electric double layer capacitor of the present invention is not particularly limited as long as it is a compound capable of binding the electrode active materials to each other. A suitable binder 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 preferably fluorine-based polymers and diene-based binders. A polymer or an acrylate polymer, more preferably a diene polymer or an acrylate polymer.

  The diene polymer is a homopolymer of a conjugated diene or a copolymer obtained by polymerizing a monomer mixture containing a conjugated diene, or a hydrogenated product thereof. The proportion of the conjugated diene in the monomer mixture is usually 40% by weight or more, preferably 50% by weight or more, more preferably 60% 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); Examples thereof include vinyl cyanide / conjugated diene copolymers such as acrylonitrile / butadiene copolymer (NBR); hydrogenated SBR, hydrogenated NBR, and the like.

  The acrylate polymer is a polymer containing a monomer unit derived from an acrylate ester and / or a methacrylate ester. The proportion of monomer units derived from acrylic acid ester and / or methacrylic acid ester 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 monomer units derived from the acrylate ester and / or methacrylate ester is in the above range is used, the heat resistance is high, and the internal resistance of the obtained electric double layer capacitor electrode is reduced. it can. Specific examples of the acrylate polymer (in the case of a copolymer) include, for example, 2-ethylhexyl acrylate / acrylonitrile copolymer, 2-ethylhexyl acrylate / methacrylonitrile copolymer, 2-ethylhexyl acrylate / methacrylic acid. Acid / acrylonitrile copolymer, 2-ethylhexyl acrylate / methacrylic acid / methacrylonitrile copolymer, butyl acrylate / acrylonitrile copolymer, butyl acrylate / acrylic acid copolymer, 2-ethylhexyl acrylate / styrene / Examples thereof include methacrylic acid copolymers and butyl acrylate / methyl methacrylate / methacrylic acid copolymers.

  The glass transition temperature (Tg) of the binder is preferably 50 ° C. or lower, more preferably −100 to 0 ° C. When the Tg of the binder is within this range, the binding property is excellent with a small amount of use, the electrode strength is high, the flexibility is high, and the electrode density can be easily increased by a pressing process during electrode formation.

  The shape of the binder used for the electrode for the electric double layer capacitor of the present invention is not particularly limited, but the binding property is good, and it is possible to suppress deterioration of the capacity of the prepared electrode and repeated charge / discharge. Since it can do, it is preferable that it is 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 number average particle diameter of the binder used for the electric double layer capacitor electrode of the present invention is not particularly limited, but is usually 0.0001 to 100 μm, preferably 0.001 to 10 μm, more preferably 0.01. It has a number average particle diameter of ˜1 μm. When the number average particle diameter of the binder is within this range, an excellent binding force can be imparted to the polarizable electrode even when a small amount of the binder is used. 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 amount of the binder is usually 0.1 to 50 parts by weight, preferably 0.5 to 20 parts by weight, and more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the electrode active material. When the amount of the binder is within this range, sufficient adhesion between the obtained electrode composition layer and the current collector can be ensured, the capacity of the electric double layer capacitor can be increased, and the internal resistance can be decreased.

(Polydibasic acid)
The polydibasic acid used for the electrode for an electric double layer capacitor of the present invention refers to a homopolymer of dibasic acid or a copolymer of dibasic acids. Examples of the polydibasic acid include polymaleic acid, polyfumaric acid, and polyitaconic acid. Of these, polymaleic acid and polyitaconic acid are preferable. When polymaleic acid or polyitaconic acid is used, the floating characteristics can be further improved because the decomposition of the electrolyte solution is suppressed without itself being decomposed.

  The number average molecular weight of the polydibasic acid used for the electric double layer capacitor electrode of the present invention is usually in the range of 5,000 to 500,000, preferably 10,000 to 300,000, more preferably 50,000 to 150,000. The number average molecular weight is a polystyrene equivalent value measured by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent. When the number average molecular weight of the polydibasic acid is within this range, the polydibasic acid is uniformly dispersed in the electrode composition layer, and the internal resistance of the electric double layer capacitor can be lowered. These polydibasic acids can be used alone or in combination of two or more. The amount of the polydibasic acid is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, more preferably 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the electrode active material. When the amount of the polydibasic acid is within this range, the decomposition of the electrolytic solution can be suppressed, the floating characteristics can be improved, and the operating voltage can be increased.

(Electrode composition)
The electrode composition used for the electrode for the electric double layer capacitor of the present invention contains the above electrode active material, conductive material, binder and polydibasic acid as essential components, and other dispersants and additives as necessary. can do. Specific examples of other dispersants include cellulosic polymers such as carboxymethylcellulose, methylcellulose, ethylcellulose and hydroxypropylcellulose, and ammonium or alkali metal salts thereof; poly (meth) acrylic such as sodium poly (meth) acrylate. Acid salts: 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 these dispersants can be used within a range that does not impair the effects of the present invention, and is not particularly limited, but is usually 0.1 to 10 parts by weight with respect to 100 parts by weight of the electrode active material, Preferably it is 0.5-5 weight part, More preferably, it is the range of 0.8-2 weight part.

  The method for producing the electrode composition is not particularly limited. Specifically, an electrode active material, a conductive material, a binder, a method for preparing a paste-like mixed material containing a polydibasic acid and a solvent, an electrode active material, a conductive material, a binder, and a polydibasic acid And the like.

(Electrode composition layer)
The electrode composition layer used for the electrode for an electric double layer capacitor of the present invention specifically forms the electrode composition on a current collector, but the formation method is not limited. Specific examples include a wet molding method and a dry molding method.

The density of the electrode composition layer used for the electric double layer capacitor electrode of the present invention is not particularly limited, but is usually 0.30 to 2.0 g / cm ³ , preferably 0.35 to 1.0 g / cm ³ , More preferably, it is 0.40 to 0.70 g / cm ³ .

  The thickness of the electrode composition layer used for the electric double layer capacitor electrode of the present invention is not particularly limited, but is usually 5 to 600 μm, preferably 20 to 500 μm, more preferably 30 to 300 μm.

(Current collector)
Specifically, the current collector used for the electrode for the electric double layer capacitor of the present invention can be made of metal, carbon, conductive polymer, and the like, preferably metal. As the current collector metal, aluminum, platinum, nickel, tantalum, titanium, other alloys and the like are usually used. Among these, it is preferable to use aluminum or an aluminum alloy in terms of conductivity and voltage resistance. In addition, the current collector can have a conductive adhesive layer including a conductive material and a binder on the current collector.

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

  The thickness of the current collector used for the electrode for the electric double layer capacitor of the present invention is appropriately selected according to the purpose of use, but is usually 1 to 200 μm, preferably 5 to 100 μm, more preferably 10 to 50 μm. When the thickness of the current collector is in this range, the resistance of electron movement can be reduced, and the internal resistance can be reduced.

In the electrode for an electric double layer capacitor of the present invention, when it has a conductive adhesive layer, the conductive adhesive layer is formed by applying a slurry composition for forming the conductive adhesive layer to the current collector and drying it. Can be formed.
The slurry composition can be produced by kneading a conductive material, a binder, and a dispersant added as necessary in water or an organic solvent as essential components.

Examples of the conductive material, the binder, and the dispersant added as necessary in the conductive adhesive layer include the conductive material, the binder, and the dispersant used in the electrode composition layer.
The obtained slurry composition for forming a conductive adhesive layer is applied to a current collector and dried to form a conductive adhesive layer. Alternatively, the conductive adhesive layer may be formed by applying and drying the slurry composition on the electrode composition layer. By forming the conductive adhesive layer, the binding property between the electrode composition layer and the current collector is improved and the internal resistance is reduced.

  The method for forming the conductive adhesive layer is not particularly limited. For example, it is formed on the current collector or the electrode composition layer by a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating, or the like.

  The thickness of the conductive adhesive layer is usually 0.01 to 20 μm, preferably 0.1 to 10 μm, and particularly preferably 1 to 5 μm. When the thickness of the conductive adhesive layer is within the above range, good adhesiveness can be obtained and the electron transfer resistance can be reduced.

(Electric double layer capacitor)
The electric double layer capacitor of the present invention is characterized by using the electric double layer capacitor electrode, and specifically comprises the electric double layer capacitor electrode, a separator, and an electrolytic solution.

  A separator will not be specifically limited if it can insulate between the electrodes for electric double layer capacitors, and can let a cation and an anion pass. Specifically, polyolefins such as polyethylene and polypropylene, microporous membranes or nonwoven fabrics made of rayon or glass fiber, and porous membranes mainly made of pulp called electrolytic capacitor paper can be used. A separator is arrange | positioned between the electrodes for electric double layer capacitors 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.

The electrolytic solution is usually composed of an electrolyte and a solvent. As the electrolyte, (1) imidazolium, (2) quaternary ammonium, (3) quaternary phosphonium, (4) lithium and the like as shown below can be used as the cation.
(1) Imidazolium 1,3-dimethylimidazolium, 1-ethyl-3-methylimidazolium, 1,3-diethylimidazolium, 1,2,3-trimethylimidazolium, 1,2,3,4-tetramethyl Imidazolium, 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 dimethylammonium, triethylmethylammonium, tetraethylammonium, trimethylpropylammonium, etc. (3) Quaternary phosphonium Tetramethylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, methyltriethylphosphonium, methyltributylphosphonium, dimethyldiethylphosphonium, etc. 4) Lithium

Similarly, the electrolyte has PF ₆ ⁻ , BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , N (RfSO ₃ ) ²⁻ , C (RfSO ₃ ) ³⁻ , RfSO ₃ ⁻ (Rf is respectively A fluoroalkyl group having 1 to 12 carbon atoms), F ⁻ , ClO ₄ ⁻ , AlCl ₄ ⁻ , AlF ₄ ^{− and the} like can be used. 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 above-mentioned capacitor element is impregnated with an electrolytic solution to obtain the electric double layer capacitor of the present invention. Specifically, the capacitor element can be manufactured by winding, stacking, or folding into a container as necessary, and pouring the electrolyte into the container and sealing it. Moreover, what impregnated the electrolytic solution beforehand in the capacitor element may be stored in the container. Any known container such as a coin shape, a cylindrical shape, or a square shape can be used as the container.

  Hereinafter, the electric double layer capacitor of the present invention will be described more specifically with reference to Examples and Comparative Examples, but 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 was measured in accordance with the following method.

(1) Electrical characteristics The electrostatic capacity and internal resistance of the coin cell-shaped electric double layer capacitors produced in the examples and comparative examples were measured by performing charge / discharge operations after allowing the produced coin cells to stand for 24 hours. Here, charging was started at a constant current of 1 mA, and when the voltage reached 3.3 V, the voltage was maintained to be constant voltage charging, and the charging was completed when the charging current decreased to 0.5 mA. Discharging was performed immediately after completion of charging until reaching 0 V at a constant current of 1 mA. The electrostatic capacity was calculated as the electrostatic capacity per weight of the active material used in the electric double layer capacitor using the energy conversion method at the time of discharging. The internal resistance was calculated from the voltage drop immediately after discharge.
(2) Floating characteristic evaluation The coin cell-shaped electric double layer capacitor manufactured in the example and the comparative example whose electric characteristics were measured in the above (1) was held at 3.3 V for 72 hours in a 70 ° C environment (floating). Thereafter, discharging was performed at a constant current of 1 mA until reaching 0V. Then, the capacitance after floating is calculated, and from the change from the capacitance before floating (the capacitance calculated in (1) above), the capacity retention ratio (= capacitance after floating / before floating) (Capacitance) was calculated, and 80% or more was evaluated as ○, and less than 80% was evaluated as ×.

Example 1
100 parts of activated carbon powder (RP-20; manufactured by Kuraray Chemical Co., Ltd.), a steam activated charcoal made from a phenol resin having a volume average particle diameter of 5 μm as an electrode active material, and a 1.5% aqueous solution of carboxymethyl cellulose (DN) as a dispersant -800H; manufactured by Daicel Chemical Industries, Ltd.) 1.5 parts by solid content, 5 parts of acetylene black (Denka black powder; manufactured by Denki Kagaku Kogyo Co., Ltd.) as a conductive material, and a number average particle diameter of 0.25 μm as a binder. 3 parts by weight of a 40% aqueous dispersion of an acrylate-based polymer, 0.5 parts by weight of 40% aqueous dispersion of polyitaconic acid (number average molecular weight 70,000), and ion-exchanged water, It mixed so that it might become 35% of density | concentration, and the slurry for electrode composition layers was prepared. As the acrylate polymer, a copolymer obtained by emulsion polymerization of 80 parts of 2-ethylhexyl acrylate and 20 parts of acrylonitrile was used.

The electrode composition layer slurry was applied to a 30 μm thick aluminum current collector with a doctor blade, dried at 60 ° C. for 20 minutes and 120 ° C. for 20 minutes, punched into a 12 mm diameter circle, 100 μm thick, and density An electrode for an electric double layer capacitor of 0.58 g / cm ³ was obtained.

  Using 40 μm-thick cellulose (TF40; manufactured by Nippon Kogyo Paper Industries Co., Ltd.) as the electrode and separator, the electrolyte solution was impregnated at room temperature for 1 hour, and then the electrode composition layer was placed inside through the separator. The coin cell-shaped electric double layer capacitor was produced by arranging the electrodes so that the electrodes do not come into electrical contact with each other. As the electrolytic solution, 1.0 mol / L tetraethylammonium fluoroborate using propylene carbonate as a solvent was used. Table 1 shows the measurement results of the electric characteristics and floating characteristics of this electric double layer capacitor.

(Example 2)
An electrode composition layer, an electrode and an electric double layer capacitor were produced in the same manner as in Example 1 except that 2 parts of polyitaconic acid was used. Table 1 shows the measurement results of the electric characteristics and floating characteristics of this electric double layer capacitor.

(Example 3)
An electrode composition layer, an electrode and an electric double layer capacitor are produced in the same manner as in Example 1 except that polymaleic acid (number average molecular weight 100,000) is used instead of polyitaconic acid. Table 1 shows the measurement results of the electric characteristics and floating characteristics of this electric double layer capacitor.

(Comparative Example 1)
An electrode composition layer, an electrode and an electric double layer capacitor were produced in the same manner as in Example 1 except that polyitaconic acid was not used. Table 1 shows the measurement results of the electric characteristics and floating characteristics of this electric double layer capacitor.

(Comparative Example 2)
An electrode composition layer, an electrode, and an electric double layer capacitor were prepared in the same manner as in Example 1 except that 0.5 part of itaconic acid was used instead of polyitaconic acid. Table 1 shows the measurement results of the electric characteristics and floating characteristics of this electric double layer capacitor.

(Comparative Example 3)
An electrode composition layer, an electrode and an electric double layer capacitor were produced in the same manner as in Example 1 except that 0.5 part of polyphosphate was used instead of polyitaconic acid. Table 1 shows the measurement results of the electric characteristics and floating characteristics of this electric double layer capacitor.

(Comparative Example 4)
An electrode composition layer, an electrode, and an electric double layer capacitor were prepared in the same manner as in Example 1 except that 0.5 part of polyacrylic acid was used instead of polyitaconic acid. Table 1 shows the measurement results of the electric characteristics and floating characteristics of this electric double layer capacitor.

(Table 1)

  As is clear from the above examples and comparative examples, in the electric double layer capacitor using the electric double layer capacitor electrode of the present invention, the internal resistance can be lowered and the floating characteristics are good. Can be suppressed, and the operating voltage can be increased.

Claims (4)

  Electric double layer capacitor in which an electrode composition layer comprising an electrode active material, a conductive material, a binder, and a polydibasic acid having a number average molecular weight in the range of 50,000 to 150,000 is formed on a current collector Electrode.   The electrode for an electric double layer capacitor according to claim 1, comprising 0.01 to 10 parts by weight of the polydibasic acid with respect to 100 parts by weight of the electrode active material. The electrode for an electric double layer capacitor according to claim 1 or 2, wherein the binder is an acrylate polymer. An electric double layer capacitor using the electric double layer capacitor electrode according to any one of claims 1 to 3 .