JP2002231589A - Electrode for electric double-layered capacitor and electric double-layered capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mainly provide an electrode for an electric double-layered capacitor which has a large capacity per volume, superior adhesive strength between an electrode layer and an electricity collector, and low internal resistance, and an electric double-layered capacitor which uses the electrode. SOLUTION: This electrode is for the electric double-layered capacitor which has a positive electrode, a negative electrode, the electricity collector, and an electrolyte, and characterized in that (1) the positive and negative electrodes contain at least activated carbon and a binder, and (2) the binder is polyvinylidene fluoride containing calboxylic acid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode for an electric double layer capacitor, and more particularly, to an electrode for an electric double layer capacitor including at least activated carbon and a specific binder in a positive electrode and a negative electrode, and an electric electrode using the electrode. It relates to a double layer capacitor.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of effective use of energy with the aim of conserving resources and the problem of global environment, a home-use decentralized power storage system for storing power at night and power for photovoltaic power generation has been developed. Power storage systems are attracting attention. As power storage devices used in these power storage systems, batteries such as lithium secondary batteries and nickel-metal hydride batteries characterized by high energy density, and capacitors characterized by high output and high reliability have been actively developed. ing.

[0003] In particular, with regard to capacitors, electric double layer capacitors using activated carbon for electrodes have attracted attention because of their low material cost and easy manufacture.

An electric double layer capacitor using the above-mentioned activated carbon for an electrode can be expected to have high output and high reliability exceeding 100,000 cycles. However, this electric double layer capacitor has a small capacity per volume of an electrode, and when it is intended to function as a sufficient power storage device, an increase in the volume of the electric double layer capacitor is a limiting condition, and in some cases, it is not practical. Many. In particular, 2k is used for electric double layer capacitors for hybrid vehicles or automotive starters.
An output density exceeding W / l is required, and practical use of an electric double layer capacitor having both high output density and high energy density is strongly demanded.

In order to obtain a high-output electric double layer capacitor, it is necessary to lower the internal resistance. The internal resistance of the electric double layer capacitor is greatly affected not only by the conductivity of the electrode part but also by the conductivity of the electrolytic solution.

[0006] Electrolyte solutions are broadly classified into aqueous systems and organic solvent systems. As for the electric conductivity, when the aqueous electrolyte and the organic solvent are compared, the aqueous electrolyte shows a higher value, but the withstand voltage is low and it is difficult to take out large energy. In contrast,
Organic solvent-based electrolytes have a high withstand voltage and are effective for extracting large energy. Therefore, research and development of electric double layer capacitors using the same have been widely performed.

In an electric double layer capacitor using an organic solvent-based electrolyte, the thickness of the electrode layer is reduced and the area of the electrode is increased in order to reduce the high internal resistance due to the low electrical conductivity of the electrolyte. It has been practiced to increase the total area of the electrodes by winding, or by laminating the electrodes in multiple layers.

However, in order to reduce the internal resistance of the electric double layer capacitor, it is not sufficient to simply increase the electrode area as described above. For example, when an electrode material slurry is applied to the surface of a metal foil such as a copper foil or an aluminum foil by a doctor blade or the like and dried to manufacture an electrode, it may be difficult to collect current. In such a case, separation occurs between the electrode layer and the metal foil, and the internal resistance increases during the production or use of the electric double layer capacitor, or the self-discharge characteristic deteriorates. It is considered that the reliability of the double layer capacitor is adversely affected.

[0009]

Accordingly, the present invention provides an electrode for an electric double layer capacitor having a high capacity per volume, excellent adhesion between an electrode layer and a current collector, and low internal resistance, and the electrode. An object of the present invention is to provide an electric double layer capacitor using the same.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies while paying attention to the above-mentioned problems of the prior art, and as a result, when a specific polymer is used as a binder for a positive electrode and a negative electrode member, It has been found that an electrode exhibiting excellent effects can be obtained in an electric double layer capacitor.

That is, the present invention provides the following electrode for an electric double layer capacitor and an electric double layer capacitor using the same. 1. An electrode for an electric double layer capacitor comprising a positive electrode, a negative electrode, a current collector and an electrolyte, wherein (1) the positive electrode and the negative electrode contain at least activated carbon and a binder, and (2) the binder is a carboxylic acid. An electrode for an electric double layer capacitor, characterized by being polyvinylidene fluoride containing: 2. The activated carbon has a specific surface area of 1300 by a BET method.
m ² / g or more 2200m and ² / g or less, the powder packing density is not more than 0.45 g / cm ³ or more 0.70 g / cm ^3, average particle size and wherein the at 1μm or more 7μm or less Item 2. The electrode for an electric double layer capacitor according to item 1 above. 3. Item 3. The electricity according to item 1 or 2, wherein the activated carbon has a 90% particle size of 6 to 22 μm in a volume-based cumulative distribution and a 10% particle size of 0.1 to 2 μm in a volume-based cumulative distribution. Electrode for double layer capacitor. 4. Item 4. The electrode for an electric double layer capacitor according to any one of Items 1 to 3, wherein the positive electrode and the negative electrode further include carbon black as a conductive material. 5. Item 5. The electrode for an electric double layer capacitor according to any one of Items 1 to 4, wherein the electrolytic solution is an organic solvent solution obtained by dissolving a salt in an aprotic organic solvent. 6. Item 6. The electrode for an electric double layer capacitor according to any one of Items 1 to 5, wherein the current collector is a metal foil or an expanded metal. 7. Item 7. The electrode for an electric double layer capacitor according to Item 6, wherein the current collector is an aluminum foil. 8. Item 8. The electric double layer capacitor electrode according to Item 6 or 7, wherein the current collector includes a conductive thin film, and the positive electrode and the negative electrode are formed on the current collector via the conductive thin film. 9. Item 10. An electric double layer capacitor using the electrode according to any one of the above items 1 to 8. 10. Item 10. The electric double layer capacitor according to Item 9, wherein the charging voltage is 1.8 to 3.3 V.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electric double layer capacitor according to the present invention will be described with reference to the drawings showing one embodiment of the present invention.

FIG. 1 is a schematic sectional view showing an example of the configuration of an electric double layer capacitor according to the present invention.

As shown in FIG. 1, a pair of electrodes 1, 1 ′ with a separator 2 interposed are housed in an outer can 4. The separator 2 and the electrodes 1, 1 'are impregnated with an electrolytic solution, and the electrodes 1, 1' and the current collectors 3, 3 'are laminated in order to extract a current to the outside. It is connected. The shape of the electric double layer capacitor is not particularly limited, and it can be formed into various shapes such as a film type, a coin type, a cylindrical type, and a box shape.

The electrodes 1, 1 'can be manufactured according to a known method. That is, the electrode-collector laminate is prepared by applying a conductive paint on the surface of the sheet-like metal (or metal foil) serving as the current collectors 3 and 3 ', drying the conductive paint, and then forming a conductive thin film (not shown). After forming, according to a conventional method in the production of a known electric double layer capacitor electrode, a slurry obtained by dispersing an activated carbon-binder mixture in a solvent such as N-methylpyrrolidone is applied on the conductive thin film, dried, and pressed. By doing so, it can be manufactured. As the current collector, metal foil (aluminum foil, stainless steel foil, copper foil, and the like), etched metal foil, expanded metal, and the like are used, and among these, aluminum foil is more preferable. The thickness of the current collector is not particularly limited, but is usually about 10 to 70 μm, and more preferably about 20 to 50 μm. If the sheet metal is too thin, it becomes difficult to handle, while if it is too thick, the volume occupied by the metal portion in the electrode becomes large and the capacity is reduced.

The conductive thin film as the intermediate intermediate layer of the electrode-collector laminate is formed by using a graphite-containing coating composition using a thermoplastic resin as a binder. The thermoplastic resin is not particularly limited, but is preferably an ethylene-acrylic acid copolymer. Graphite is also not particularly limited, and examples thereof include natural graphite, artificial graphite, and pulverized products of graphitized carbon fibers. The average particle size of the graphite particles is equal to or less than the thickness of the conductive thin film, usually about 0.05 to 20 μm, and more preferably about 0.1 to 10 μm. The coating composition for forming a conductive film may contain carbon, metal powder, and the like in addition to graphite. The thickness of the conductive film is usually about 0.5 to 10 μm, more preferably 1 to 5 μm
m. If the conductive film is too thin, it is difficult to obtain sufficient current collection, while if too thick, the volume of the activated carbon-containing electrode layer described below formed on the film is relatively reduced, It is difficult to obtain capacity.

The electrode is formed by applying a mixture containing activated carbon and a binder on a conductive thin film previously formed on the surface of the current collector.

For the BET method of the activated carbon contained in the electrodes 1, 1 '
Specific surface area is 1300m^Two/ g or more 2200m ^Two/ g or less
1400m^Two/ g or more 2000m^Two/ g or less. Specific surface area
1300m ^Two/ g, the packing density increases, but the weight
Per volume or the amount of liquid retained decreases,
This is not preferable because sufficient output characteristics cannot be obtained. On the other hand, the ratio
Surface area 2200m^Two/ g, the packing density decreases.
It is not preferable because a sufficient capacity cannot be obtained.

The filling property of the activated carbon depends on the shape, particle size distribution, surface condition and the like of the particles. As a method for evaluating the filling property, a tap density, a powder filling density, and the like can be mentioned. The present inventors have found that the powder packing density has a high correlation with the electrode density. That is, electrode 1,
Powder packing density of the activated carbon contained in 1 'is a 0.45 g / cm ³ or more 0.70 g / cm ³ or less, preferably 0.45 g / cm ³ 0.65
g / cm ³ or less. If the powder packing density is less than 0.45 g / cm ³ , the electrode density is reduced, and a sufficient capacity cannot be obtained, which is not preferable. On the other hand, when the powder packing density is more than 0.70 g / cm ³ is the powder packing density is improved, or reduced capacity per weight, or the liquid retaining amount is reduced, sufficient output characteristics It is not preferable because it cannot be obtained.

The average particle size of the activated carbon contained in the electrodes 1 and 1 'is 1 μm or more and 7 μm or less, preferably 1 μm or less.
Not less than 5 μm. If the average particle size is less than 1 μm, secondary agglomeration and the like of the powder become intense and a problem occurs during electrode molding, which is not preferable. On the other hand, the average particle size is 7 μm
If it exceeds, it is not preferable because the electrode density decreases and a sufficient capacity cannot be obtained. Furthermore, in addition to the above conditions of the average particle diameter, in the activated carbon, the 90% particle diameter of the volume-based cumulative distribution is 6 μm or more and 22 μm or less, and the 10% particle diameter of the volume-based cumulative distribution is 0.1 μm or more and 2 μm. More preferably, the 90% particle size of the volume-based cumulative distribution is 6 μm or more and 20 μm or less, and the 10% particle size of the volume-based cumulative distribution is more preferably 0.1 μm or more and 2 μm or less. . When such conditions are satisfied, the particle size of the activated carbon has a relatively wide distribution, and the activated carbon has a fine powder less than 0.1 μm and a small amount of coarse particles exceeding 22 μm, thereby further increasing the capacity per volume. be able to.

In the present specification, the “average particle size” of various granular components means a central particle size in a volume particle size distribution obtained by a laser diffraction type particle size distribution measuring method.

In the present invention, it is desirable to use activated carbon particles having the above specific surface area and average particle diameter. The method for producing such activated carbon particles is not particularly limited, and for example, a method described in "New Edition Activated Carbon Basics and Applications" by Yuzo Sanada et al. Can be used. In general, activated carbon is often produced in the form of powder, fibers or the like having an average particle diameter of 10 μm or more.In order to obtain activated carbon having a specific specific surface area and an average particle diameter, a ball mill, a jet mill, or the like is used. It is preferable to adjust the properties of the material using a pulverizer and a classifier. Or,
The activated carbon satisfying the above conditions may be obtained by controlling the raw material, the activation method, the shape of the activated carbon to be primarily synthesized, and the like.

The binder used in the electrode layer forming mixture is not particularly limited, but carboxylic acid-modified polyvinylidene fluoride, a carboxylic acid / polyvinylidene fluoride mixture, and the like are preferable. Examples of the carboxylic acid include maleic acid and oxalic acid, and maleic acid is particularly preferable. In forming the activated carbon-containing electrode layer by coating, it is preferable to use a solution in which carboxylic acid-modified polyvinylidene fluoride is dissolved in N-methylpyrrolidone as a solvent, and a solution in which a mixture of polyvinylidene fluoride / carboxylic acid is dissolved is used. May be used. The amount of the binder to be added is not particularly limited, and may be appropriately determined depending on the particle size of the activated carbon, the particle size distribution, the particle shape, the target electrode density, and the like.
About 25% by weight, more preferably about 7 to 20% by weight.

The carboxylic acid-modified polyvinylidene fluoride is
By copolymerizing a monomer containing at least 80% by weight of vinylidene fluoride and a carboxylic acid monoester,
Can be manufactured. Examples of the monomer containing vinylidene fluoride include vinylidene fluoride alone, and a mixture of vinylidene fluoride and at least one of monomers copolymerizable with vinylidene fluoride (eg, vinyl fluoride, trifluoroethylene, and tetrafluoroethylene). As the carboxylic acid monoester, those having 5 to 8 carbon atoms are preferable, and more specifically, monomethyl maleate, monoethyl maleate and the like are exemplified. Such carboxylic acid-modified polyvinylidene fluoride is a known material and is commercially available.
The content of the carboxylic acid in the carboxylic acid-modified polyvinylidene fluoride can be appropriately selected from a wide range, but the amount to be charged is usually 0.1 to 3% by weight based on the polyvinylidene fluoride.
And more preferably about 0.3 to 2% by weight.
Also, when using a mixture of carboxylic acid and polyvinylidene fluoride, the amount of carboxylic acid can be appropriately selected from a wide range, but is generally about 0.01 to 2% by weight based on polyvinylidene fluoride, More preferably 0.05-1
% By weight.

Known additives such as conductive materials (for example, carbonaceous materials such as acetylene black, Ketjen black, carbon black and graphite, metal powders, etc.) may be added to the mixture for forming an electrode layer containing activated carbon and a binder. Materials may be blended.

The shape of the electrodes 1, 1 'is appropriately determined according to the shape and size of the capacitor, the characteristics to be satisfied by the capacitor, and the like. For example, when the capacitor is box-shaped, a sheet-like electrode-current collector laminate having a thickness of about 0.1 to 30 mm can be used, and when the capacitor is cylindrical,
An electrode formed by winding an electrode and a metal current collector foil such as an aluminum foil, a stainless steel foil, or a copper foil having a thickness of about 0.02 to 2 mm via a conductive thin film can be used.

As the separator 2, a known material such as a microporous film or nonwoven fabric made of polyolefin such as polyethylene or polypropylene, or a porous film mainly made of pulp generally called electrolytic capacitor paper can be used. As described above, in general, the electrodes of the electric double layer capacitor are often separated by a porous separator impregnated with an electrolyte, but instead of the electrolyte impregnated separator, a solid electrolyte or A gel electrolyte may be used.

The electrolyte used for the electrodes 1, 1 'and the separator 2 is not particularly limited, but it is preferable to use a non-aqueous electrolyte, and it is more preferable to use an organic electrolyte having a high voltage per unit cell. . The organic solvent is not particularly limited, and known aprotic solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulfolane, and acetonitrile are suitable, and one or more of these solvents are preferable. It is preferred to use a mixture of two or more. As the electrolyte, although not particularly limited, known electrolytes such as tetraethylammonium tetrafluoroborate, triethylmethylammonium tetrafluoroborate, and tetraethylammonium hexafluorophosphate can be used, and one or two of these can be used. Mixtures of the above can be used.
The organic electrolyte is usually 0.5 to 3.0 mol / l (more preferably about 0.7 to 2.0 mol / l) with respect to the aprotic organic solvent.
Use what is dissolved in.

The charging voltage of the electric double layer capacitor configured as described above may be appropriately determined in consideration of the type of activated carbon used for the electric double layer capacitor, the electrolytic solution, the operating temperature, the intended life, and the like. When an organic electrolytic solution is used, it is preferable to set the range of 1.8 to 3.3V. If the charging voltage is less than 1.8 V, the available capacity is reduced, which is not preferable. If the charging voltage is more than 3.3 V, the decomposition of the electrolytic solution is undesirably increased.

Through the steps described above, an electrode for an electric double layer capacitor containing a specific binder and activated carbon is obtained.

Further, the electric double layer capacitor according to the present invention can be manufactured by a general method for manufacturing an electric double layer capacitor, and thus is excellent in industrial mass productivity.

[0032]

The present invention will be described more specifically below with reference to examples of the present invention.

Example 1 Activated carbon powder obtained by pulverizing activated carbon ("MSC-25", manufactured by Kansai Thermochemical Co., Ltd.) with a ball mill for 60 hours was used. The specific surface area of the activated carbon is 1950 m ² / g, and the powder packing density is 0.49 g / g.
cm ³ , average particle size is 2.8 μm, 10% particle size is 0.9 μm, 90%
The particle size was 7.5 μm.

The specific surface area, powder packing density, and particle size distribution of the activated carbon powder were measured by the following methods.

A: Specific surface area A BET specific surface area measurement apparatus (“NOVA1200”, manufactured by Yuasa Ionics) was used to measure a sample amount of 10 mg.

B: Powder filling density As shown in FIG. 2, an inner diameter of 5 mm with the lower lid 12 fixed below.
100 mg of activated carbon was placed in the glass tube 11, and the length L (cm) of the activated carbon in the vertical direction was determined in a state where the powder was compressed by the upper lid 13 at a pressure of 70 kg / cm ² . Using the determined length L, the powder packing density ρ was determined from the following equation: ρ = 0.1 / (0.25 × 0.25 × 3.14 × L).

C: Particle size distribution Measured using a laser diffraction particle size distribution analyzer (SALD) manufactured by Shimadzu Corporation. The activated carbon powder was ultrasonically dispersed in water containing a small amount of a commercially available neutral detergent, and then measured to obtain an average particle diameter, a 10% particle diameter of a volume-based cumulative distribution, and a 90% particle diameter.

NPC (N-methylpyrrolidone) solution of 93 parts by weight of the activated carbon powder, 7 parts by weight of ketjen black as a conductive material and maleic acid-modified polyvinylidene fluoride ("KF Polymer 9130" manufactured by Kureha Chemical Industry Co., Ltd.): Solid content 13
By weight, 15 parts by weight (as solid content) and 400 parts by weight of NMP (including NMP in the polymer solution) were sufficiently mixed to obtain a slurry containing activated carbon-binder.

Next, a graphite-containing conductive film (conductive paint “EB-012” manufactured by Acheson Japan Co., Ltd.) was applied on a 22 μm-thick aluminum foil, and dried at 120 ° C. for 10 minutes to form a binder. = Ethylene-acrylic acid copolymer), the slurry was applied, dried (120 ° C x 10 minutes), and pressed to obtain a 170 µm-thick electrode-collector laminate. The electrode-current collector laminate was used below as a positive electrode-current collector laminate and a negative electrode-current collector laminate.

Next, after the positive electrode-current collector laminate and the negative electrode-current collector laminate (each 1.5 × 1.5 cm ² ) were impregnated with an electrolytic solution, the separator was impregnated with the same electrolytic solution. An electric double layer capacitor of the type shown in FIG. 1 was assembled in a dry box by sandwiching between copper plates. At this time, a 55 μm-thick electrolytic capacitor paper was used as a separator, and a solution in which (C ₂ H ₅ ) ₄ NBF ₄ was dissolved in propylene carbonate at a concentration of 1 mol / l was used as an electrolytic solution.

The obtained electric double layer capacitor was regulated at a maximum current of 50 mA, charged at 2.5 V for 30 minutes, and then discharged at a current of 1 mA until the capacitor voltage became 0 V. This cycle is repeated, and the capacity is determined from the slope of the discharge curve between 2.0 and 1.5 V in the fifth cycle, and the capacity per electrode volume (F / c) is determined from the total volume of the two electrodes and the capacity of the electric double layer capacitor.
m ³ ) was determined.

The AC internal resistance of the electric double layer capacitor
(1 kHz) was 0.7Ω.

The results are summarized in Table 1.

Comparative Example 1 As in Example 1, 93 parts by weight of activated carbon powder, 7 parts by weight of Ketjen black as a conductive material, 15 parts by weight of polyvinylidene fluoride powder containing no maleic acid, and 400 parts by weight of NMP were sufficiently mixed. Thereby, an activated carbon-binder-containing slurry was obtained. Using this activated carbon-binder-containing slurry, a positive electrode-current collector laminate and a negative electrode-current collector laminate having a thickness of 170 μm were obtained in the same manner as in Example 1.

Then, an electric double layer capacitor was assembled in a dry box in the same manner as in Example 1 using the above-mentioned positive electrode-current collector laminate and negative electrode-current collector laminate, and then the capacity and the internal resistance were measured. Was measured. The results are shown in Table 1.

Example 2 Unground activated carbon (“MSC-25”, manufactured by Kansai Thermochemical Co., Ltd.)
Specific surface area = 2050 m ² / g, powder packing density = 0.42 g / cm ³ , average particle diameter = 35 μm, 10% particle diameter = 7.3 μm, 90% particle diameter = 118.5 μ
m) according to the method of Example 1 except that m) is used.
After obtaining the electrode-collector laminate of Example 2, an electric double layer capacitor was assembled in the same manner as in Example 1, and the capacitance and the internal resistance were measured. The results are shown in Table 1.

Example 3 Activated carbon (“M-15”, manufactured by Osaka Gas Co., Ltd.) was ball milled.
Activated carbon powder obtained by grinding for 24 hours (specific surface area = 1210 m ² / g, powder packing density = 0.61 g / cm ³ , average particle diameter = 3.0 μm, 10% particle diameter = 0.8 μm, 90% particle diameter = 8.2 After obtaining an electrode-collector laminate having a thickness of 170 μm according to the method of Example 1 except that (μm) was used, an electric double layer capacitor was assembled in the same manner as in Example 1, and the capacitance and internal resistance were measured. It was measured. The results are shown in Table 1.

[0048]

[Table 1] From the results shown in Table 1, the electric double-layer capacitor of the present invention according to Example 1 using an electrode containing specific activated carbon and using maleic acid-modified polyvinylidene fluoride as a binder has a capacitance per unit weight and per unit volume. It is clear that the resin exhibits extremely excellent performance because of its high internal resistance and low internal resistance.

On the other hand, the electric double layer capacitor according to Comparative Example 1, which uses polyvinylidene fluoride containing no maleic acid, cannot obtain high output because of high internal resistance.

The electric double layer capacitors according to Examples 2 and 3 using an electrode using maleic acid-modified polyvinylidene fluoride as a binder have a lower internal resistance and practicality as compared with the electric double layer capacitor according to Comparative Example 1. ing.

[0051]

According to the present invention, there is used a positive electrode and a negative electrode in which an electrode layer containing activated carbon, carbon black as a conductive material and a specific binder, and a current collector are bonded via a conductive thin film. Thereby, an electric two-layer capacitor with excellent adhesion between the electrode layer and the current collector and low internal resistance (high output) can be obtained.

Further, when a specific activated carbon having a specific surface area and an average particle diameter adjusted to an appropriate range is used, an electric double layer capacitor which achieves both the effect of large capacity per weight and volume can be obtained. .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a configuration of an electric double layer capacitor according to the present invention.

FIG. 2 is a schematic diagram for explaining a method of measuring a powder packing density in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1 'electrode 2 Separator 3, 3' current collector 4 Outer can 11 Glass tube 12 Lower lid 13 Upper lid

Claims (10)

[Claims] 1. An electrode for an electric double layer capacitor comprising a positive electrode, a negative electrode, a current collector and an electrolytic solution, wherein (1) the positive electrode and the negative electrode contain at least activated carbon and a binder; An electrode for an electric double layer capacitor, wherein the binder is polyvinylidene fluoride containing a carboxylic acid. Wherein said activated carbon, the specific surface area by the BET method is not more than 1300 m ² / g or more 2200 m ² / g, the powder packing density is 0.45 g / cm ³ or more 0.70 g / cm ³
2. The electrode for an electric double layer capacitor according to claim 1, wherein the average particle diameter is 1 μm or more and 7 μm or less. 3. The activated carbon according to claim 1, wherein the 90% particle size of the volume-based cumulative distribution is 6 μm or more and 22 μm or less, and the 10% particle size of the volume-based cumulative distribution is 0.1 μm or more and 2 μm or less. 3. The electrode for an electric double layer capacitor according to 2. 4. The electrode for an electric double layer capacitor according to claim 1, wherein the positive electrode and the negative electrode further include carbon black as a conductive material. 5. The electrode for an electric double layer capacitor according to claim 1, wherein the electrolytic solution is an organic solvent solution obtained by dissolving a salt in an aprotic organic solvent. 6. The electrode for an electric double layer capacitor according to claim 1, wherein the current collector is a metal foil or an expanded metal. 7. The electrode for an electric double layer capacitor according to claim 6, wherein the current collector is an aluminum foil. 8. The electric double layer capacitor according to claim 6, wherein the current collector includes a conductive thin film, and the positive electrode and the negative electrode are formed on the current collector via the conductive thin film. electrode. 9. An electric double layer capacitor using the electrode according to claim 1. 10. The charging voltage of 1.8 to 3.3V.
3. The electric double layer capacitor according to claim 1.