JP2009135146A - Electrode material for electric double layer capacitor, and additive for the electrode material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode material for an electric double layer capacitor for forming the electric double layer capacitor having low internal resistance, and additives for the electrode material as a constituent member of the electrode material. <P>SOLUTION: The electrode material for the electric double layer capacitor is obtained by mixing first active carbon of ≤1 μm in mean particle diameter and second active carbon of >1 μm in mean particle diameter with each other, the mean particle diameter of the first active carbon being preferably ≤0.8 μm and more preferably ≤0.5 μm and the amount of the first active carbon being preferably ≥2% by mass for 100% by mass of the first active carbon and second active carbon in total. The additives for the electrode material are used for the electrode material for the electric double layer capacitor which contains the first active carbon of ≤1 μm in mean particle diameter and with which the second active carbon of >1 μm in mean particle diameter is mixed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an electrode material for an electric double layer capacitor used for producing an electric double layer capacitor having a low internal resistance and a large capacitance, and an additive for an electrode material which is a constituent member of the electrode material. It is.

  An electric double layer capacitor is known as a large-capacity capacitor based on the principle of power storage that an electric double layer is generated at the interface between an electrolyte and an electrode. In order to use an electric double layer capacitor as a general-purpose power source for information equipment memory backup, motor drive, etc., it is desired to reduce the internal resistance of the electric double layer capacitor in order to realize efficient charge and discharge.

  Activated carbon is used as the main electrode material for the electrode of the electric double layer capacitor, and the development of an electrode material for realizing an electric double layer capacitor having excellent electric characteristics is underway. The results of the development are published in many documents.

  For example, in Patent Document 1, in order to realize an electric double layer capacitor having a low internal resistance and a large capacity, a fullerene-containing soot or an extraction residue obtained by solvent extraction of at least a part of fullerene from a fullerene-containing soot is heat-treated. Alternatively, it is disclosed that a carbonaceous material having an average particle diameter of 5 to 7 μm is produced by activation treatment, and the carbonaceous material is used in combination with activated carbon to produce an electrode.

Patent Document 2 discloses that an electrode material having a good filling property is necessary for increasing the capacity of an electric double layer capacitor, and the necessary electrode material is activated carbon having an average particle diameter of 4 to 40 μm ( It is disclosed that A) is mixed with activated carbon (B) having an average particle size of 4 μm or less. Patent Document 2 describes that the preferable average particle diameter of activated carbon (A) is 10 to 30 μm, and the preferable average particle diameter of activated carbon (B) is 1/5 or less of the average particle diameter of activated carbon (A). .
JP 2006-294817 A JP 2001-146410 A

  An object of the present invention is to provide an electrode material for an electric double layer capacitor for producing an electric double layer capacitor having at least a low internal resistance, and an additive for an electrode material which is a constituent member of the electrode material.

  The present invention is an electrode material for an electric double layer capacitor in which a first activated carbon having an average particle diameter of 1 μm or less and a second activated carbon having an average particle diameter exceeding 1 μm are mixed. The average particle diameter of the first activated carbon is preferably 0.8 μm or less for further improving internal resistance and capacitance, and 0.5 μm or less is particularly preferable for reducing the internal resistance. The amount of the first activated carbon in the electrode material according to the present invention is preferably 2% by mass or more with respect to 100% by mass of the total amount of the first activated carbon and the second activated carbon. An electrode for an electric double layer capacitor can be manufactured using the electrode material according to the present invention, and an electric double layer capacitor can be manufactured using the electrode.

  The “average particle diameter” in the present invention is a median diameter obtained by dispersing a sample in water and using a laser diffraction particle size distribution analyzer.

  The present invention is an additive for an electrode material used for an electrode material for an electric double layer capacitor having a first activated carbon having an average particle diameter of 1 μm or less and mixed with a second activated carbon having an average particle diameter exceeding 1 μm. . The additive may be either one made only of the first activated carbon or one containing a member other than the first activated carbon.

  The electrode material for an electric double layer capacitor according to the present invention includes a mixture of a first activated carbon having a predetermined average particle diameter and a second activated carbon having an average particle diameter larger than that of the first activated carbon. The internal resistance of the electric double layer capacitor can be made lower than that of the electrode material having activated carbon. And the capacitance of the electric double layer capacitor manufactured using the electrode material for electric double layer capacitor according to the present invention is an electric double layer manufactured using an electrode material having only the second activated carbon as the activated carbon. It becomes equal to or better than the capacitor.

  Moreover, since the additive for electrode materials which concerns on this invention has the 1st activated carbon of a predetermined average particle diameter, it is suitable as one structural member of the electrode material for electric double layer capacitors which concerns on this invention.

(Electrode material for electric double layer capacitor)
The electrode material for an electric double layer capacitor according to this embodiment is a mixture of first activated carbon having a predetermined average particle diameter and second activated carbon having a predetermined average particle diameter. The mixing method for preparing this mixture is not particularly limited. In the following, “electric double layer capacitor” is simply referred to as “capacitor”, “electrode for electric double layer capacitor” is simply referred to as “electrode”, and “electrode material for electric double layer capacitor” is simply referred to as “electrode material”. May be called.

  As long as the first activated carbon and the second activated carbon are mixed, the electrode material in this embodiment may be mixed with other constituent members. The constituent member is, for example, a general conductivity imparting agent (for example, acetylene black) mixed with activated carbon for the purpose of reducing the resistance of the electrode.

(First activated carbon)
The first activated carbon is activated carbon having an average particle size of 1 μm or less. When the average particle diameter of the first activated carbon exceeds 1 μm, the capacitance of the capacitor may be smaller than when only the second activated carbon is used as the activated carbon for the electrode material. The average particle diameter of the first activated carbon is preferably 0.8 μm or less in order to further reduce the internal resistance of the capacitor and increase the capacitance. In order to realize a capacitor having a particularly low internal resistance, the average particle diameter of the first activated carbon is optimally 0.5 μm or less.

The specific surface area and pore volume of the first activated carbon are not particularly limited, but the specific surface area is 500 to 2000 m ² / g, and the pore volume is 0.50 to 1.3 ml / g. The specific surface area is determined by the BET method of measuring the nitrogen adsorption isotherm of porous carbon. The pore volume is determined by relative pressure P / P ₀ (P: pressure of adsorbate gas in adsorption equilibrium, P ₀ : the saturated vapor pressure of the adsorbate at the adsorption temperature) is determined by the BET method for measuring the nitrogen adsorption amount up to 0.93.

  As the amount of the first activated carbon in the electrode material of the present embodiment is larger, the internal resistance of the capacitor is lowered and the capacitance is improved. Therefore, the amount of the first activated carbon is preferably an amount according to the desired internal resistance and capacitance. The lower limit amount of the first activated carbon is usually preferably 2% by mass and more preferably 5% by mass with respect to 100% by mass of the total amount of the first activated carbon and the second activated carbon. On the other hand, the upper limit of the first activated carbon is not particularly limited to 10% by mass, 20% by mass, or 30% by mass. However, if the amount of the first activated carbon is large, there is a problem that the moldability of the electrode is lowered. In addition, since the internal resistance of the capacitor is expected to be constant from 30% by mass or more, it is preferably 30% by mass with respect to 100% by mass of the total amount of the first activated carbon and the second activated carbon.

  A first activated carbon can be manufactured by activating the carbonaceous material which is a well-known activated carbon raw material.

  The carbonaceous material is not particularly limited. For example, non-graphitizable carbon such as wood, sawdust, charcoal, coconut husk, cellulosic fiber, synthetic resin (eg, phenol resin, furan resin); pitch (eg, mesophase pitch), coke (eg, pitch coke, needle coke) ), Graphitizable carbon such as polyvinyl chloride, polyimide, and PAN; and mixtures thereof. If necessary, a carbonaceous material that has been carbonized before the activation treatment is used as the activated carbon raw material. Here, the carbonization treatment is a treatment in which a carbonaceous material is placed in an inert gas such as nitrogen at a high temperature (for example, 900 to 1000 ° C.) and carbonization of the carbonaceous material proceeds.

  The activation treatment is a treatment for forming pores on the surface of the carbonaceous material and increasing the specific surface area and the pore volume. As this activation treatment, (1) gas activation in which activated carbon is produced by heating a carbonaceous substance in the presence of gas, and (2) activated carbon is produced by heating a mixture of the activator and the carbonaceous substance. Drug activation is known. The first activated carbon can be produced by a treatment arbitrarily selected from known activation treatments.

  When gas activation is selected, one or two or more oxidizing gases selected from water vapor, air, carbon dioxide, combustion gas, and the like are brought into contact with a carbonaceous material in a temperature atmosphere of 700 to 1000 ° C. And good. By this contact, the pore diameter, specific surface area, and pore volume of the carbonaceous material increase, and the first activated carbon is produced.

  It is preferable to select a drug activation that can easily produce the first activated carbon having a large specific surface area compared to the gas activation. As described above, this drug activation is performed by heating a mixture of an activator and a carbonaceous substance. In this case, it is preferable to use one or more selected from known activators such as phosphoric acid, sulfuric acid, calcium chloride, zinc chloride, potassium sulfide, and alkali metal compounds. Activating agents that can be easily activated include alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; alkali metal carbonates such as potassium carbonate and sodium carbonate; alkali metal such as potassium sulfate and sodium sulfate. Sulfates are preferred, alkali metal hydroxides are more preferred, and potassium hydroxide is even more preferred. The amount of the activator used is preferably 0.5 to 10 times the mass of the carbonaceous material when, for example, an alkali metal hydroxide is used as the activator. The larger the amount used, the more the first activated carbon with a larger specific surface area and average pore diameter can be produced, and the smaller the amount used, the more the activated carbon with the smaller specific surface area and average pore diameter of activated carbon can be produced.

  In drug activation, water may be mixed with the carbonaceous material and the activator in order to facilitate melting of the activator. The amount of water mixed at this time is preferably 0.05 to 10 times the mass of the activator when an alkali metal hydroxide is used as the activator.

  In heating in drug activation, the heating temperature at that time is preferably about 400 to 900 ° C. When the heating temperature is low, the specific surface area and the average pore diameter tend to decrease, and when the heating temperature is high, the specific surface area and the average pore diameter tend to increase. In addition, the heating in chemical | medical agent activation is performed by inert gas atmosphere, such as argon and nitrogen; or under reduced pressure (in a vacuum);

  The first activated carbon can be manufactured by activating the carbonaceous material, but the activated carbon material (carbonaceous material) and / or impurities derived from the activating treatment are adsorbed on the surface of the first activated carbon after the activation treatment. There is. The impurities are metal elements (iron, copper, nickel, alkali metals, etc.) and metal element compounds (hereinafter “metal elements and metal element compounds” are referred to as “metal elements”), and a large amount of such metal elements adsorb. When the first activated carbon used is used as an electrode material, it may induce a decrease in the durability of the capacitor (shortening of the capacitor life). Therefore, the first activated carbon produced by the activation process is usually washed.

  Metal elements and the like can be removed from the surface of the first activated carbon by a known cleaning method. The known cleaning methods include, for example, (1) a method in which only water is used as a cleaning solution to clean the first activated carbon, and (2) a strong acid aqueous solution in which one or more strong acids such as hydrochloric acid and sulfuric acid are mixed. And a method of washing the first activated carbon.

  Since the average particle diameter of the first activated carbon is the above-mentioned predetermined average particle diameter, when adjustment of the average particle diameter of the first activated carbon is necessary, the well-known particle diameter adjusting means appropriately selected can be used to adjust the first activated carbon. Adjust the average particle size. For example, the average particle diameter of the first activated carbon may be adjusted using a pulverizer such as a ball mill, a vibration mill, or a jet mill.

  The first activated carbon of this embodiment is as detailed above. The first activated carbon of the present embodiment can be an additive for the electrode material according to the present embodiment by itself, and is mixed with a member other than the first activated carbon (for example, a conductivity imparting agent such as acetylene black) It can be an additive. The first activated carbon is preferably mixed with a dispersion medium such as water and used in a slurry state.

(Second activated carbon)
The second activated carbon is activated carbon having an average particle size exceeding 1 μm. When importance is attached to the low temperature characteristics of the electrode material, the average particle diameter of the second activated carbon is preferably 6 μm or less, and preferably 2 to 4 μm.

The specific surface area and pore volume of the second activated carbon are not particularly limited, but usually the specific surface area is 1500-2500 m ² / g and the pore volume is 1.0-2.0 ml / g. These specific surface area and pore volume are values obtained in the same manner as the first activated carbon.

  Similar to the first activated carbon, the second activated carbon can be produced by activating the carbonaceous material. The carbonaceous material used at this time may be the same as or different from the carbonaceous material used to produce the first activated carbon. Further, the activation process may be the same process as the process used in the production of the first activated carbon or a different process. And you may wash | clean a 2nd activated carbon as needed.

  When it is necessary to adjust the average particle size of the second activated carbon, a known particle size adjusting means may be used. It is possible to adjust the average particle size to be small with a known pulverizer (for example, ball mill, vibration mill, jet mill).

(Electrode for electric double layer capacitor)
The electrode material of the present embodiment can be used as a material for an electric double layer capacitor electrode. In manufacturing the electrode, a known manufacturing method may be used. For example, the electrode material of the present embodiment in which the first activated carbon and the second activated carbon are mixed, the conductivity-imparting agent, and the binder solution are kneaded, a solvent is added to prepare a paste, and this paste is aluminum foil. After applying to a current collector plate such as the like, it is possible to produce an electrode by drying and removing the solvent.

  Examples of the binder used when manufacturing the electrode include fluorine-based polymer compounds such as polytetrafluoroethylene and polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber, petroleum pitch, and phenol resin. Examples of the conductivity-imparting agent include carbon-based conductivity imparting agents such as carbon black, acetylene black, and ketjen black; metal oxide-based conductivity imparting agents such as ruthenium oxide.

(Electric double layer capacitor)
There are known electric double layer capacitors such as a coin type, a wound type, and a multilayer type, and the capacitor generally has an electrode, an electrolytic solution, and a separator, and a structure in which a separator is disposed between a pair of electrodes. It is. Activated carbon is used as an electrode material in any capacitor.

  As the electrolytic solution, it is preferable to select a nonaqueous electrolytic solution having a nonaqueous polar solvent having a high decomposition voltage as a main solvent. As the solvent for the non-aqueous electrolyte solution, it is preferable to use one or two or more kinds selected from non-aqueous polar solvents such as propylene carbonate, ethylene carbonate, and methyl ethyl carbonate as the main solvent. Examples of the electrolyte of the electrolytic solution include salts of amidine or quaternary ammonium with perchloric acid, boron tetrafluoride or phosphorus hexafluoride. Moreover, if a separator is illustrated, the nonwoven fabric, cloth, and microporous film which have cellulose, glass fiber, or polyolefins, such as polyethylene and a polypropylene, as a main component are mentioned.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention.

  Predetermined amounts of the first activated carbon and the second activated carbon were mixed to prepare electrode materials for Examples and Comparative Examples. Moreover, an electric double layer capacitor was produced using these electrode materials. And about the produced electric double layer capacitor, the density of the electrode, an electrostatic capacitance, and an internal resistivity were computed. The details are as follows.

The average particle diameter in the following is a median diameter obtained by dispersing a sample in water and using a laser diffraction particle size distribution measuring device “SALD-2000” manufactured by Shimadzu Corporation. A specific surface area is the value calculated | required by BET method which measures the nitrogen adsorption isotherm of porous carbon using the ASAP-2400 nitrogen adsorption apparatus by a micromeritics company. The pore volume was measured using an ASAP-2400 nitrogen adsorption device manufactured by Micromeritics, and the relative pressure P / P ₀ (P: pressure of the adsorbate gas in the adsorption equilibrium, P ₀ : adsorption at the adsorption temperature) (Saturated vapor pressure of the material) is a value determined by the BET method for measuring the nitrogen adsorption amount up to 0.93.

(First activated carbon)
Activated carbon was appropriately pulverized with a planetary ball mill ("Model P-5" manufactured by Fritsch Japan) to obtain first activated carbon. The details of the first activated carbon used in the examples and comparative examples are as follows.

Examples 1a-1b, 2a-2d, 3a-3b, 9 and 11 and Comparative Examples 2 and 3:
Commercially available phenol resin activated carbon (“MAXSORB” manufactured by Carbontech Co., Ltd.) was pulverized to prepare first activated carbon. The average particle diameter, specific surface area and pore volume of the first activated carbon are 0.3 μm, 1570 m ^{2 /} g, 1.1 ml / g in Examples 1a and 1b; 0.5 μm and 1700 m in Examples 2a to 2d, respectively. ^{2 /g,1.1ml/g;} examples 3a and 3b is ^1.0μm, 1860m 2 /g,0.94ml/g; examples 9 and 11 are ^0.5μm, 1700m 2 /g,1.1ml/ g;

Example 4:
The activated carbon obtained by steam activation of the paper-phenolic resin laminate was pulverized to prepare the first activated carbon of Example 4. The average particle size was 0.5 μm, the specific surface area was 1830 m ² / g, and the pore volume was 1.2 ml / g.

Examples 5 and 10:
Petroleum coke activated carbon manufactured by Carbontech Co., Ltd., which is an alkali activated carbon of petroleum coke, was used as the first activated carbon of Examples 5 and 10. Both activated carbons had an average particle size of 0.5 μm, a specific surface area of 1710 m ² / g, and a pore volume of 0.95 ml / g.

Example 6:
A coconut shell activated carbon manufactured by Carbontech, which is a steam activated carbon of coconut shell, was used as the first activated carbon of Example 6. The activated carbon had an average particle size of 0.5 μm, a specific surface area of 1260 m ² / g, and a pore volume of 0.72 ml / g.

Example 7:
The soot generated during fullerene production (“Frontier Black” manufactured by Frontier Carbon Co., Ltd.) was steam-activated at 950 ° C. to obtain a first activated carbon of Example 7. The activated carbon had an average particle size of 0.5 μm, a specific surface area of 1180 m ² / g, and a pore volume of 0.87 ml / g.

Example 8:
Cabot's “BLACK PEARLS-1400 (granular product)” was used as the first activated carbon of Example 8. The activated carbon had an average particle size of 0.7 μm, a specific surface area of 530 m ² / g, and a pore volume of 0.54 ml / g.

(Second activated carbon)
Similarly to the first activated carbon, the activated carbon was appropriately pulverized to obtain a second activated carbon. The activated carbon used in the examples and comparative examples is as follows.

Examples 1a-1b, 2a-2d, 3a-3b, and 4-8, and Comparative Examples 1-3:
Commercially available phenol resin activated carbon (“Maxsorb” manufactured by Carbontech Co., Ltd.) was used as the second activated carbon in Example 1a and the like. In any second activated carbon, the average particle size was 3 μm, the specific surface area was 2310 m ² / g, and the pore volume was 1.1 ml / g.

Examples 9-11 and Comparative Examples 4-5:
The carbon coke-based activated carbon coke activated carbon produced by alkali activation of petroleum coke was used as the second activated carbon in Example 9. The average particle size of Example 9, Example 10, and Comparative Example 4 is 3 μm, the specific surface area is 2280 m ² / g, the pore volume is 1.1 ml / g; the average particle size of Example 11 and Comparative Example 5 is 5 μm, specific surface area was 2380 m ² / g, and pore volume was 1.2 ml / g;

(Capacitor production)
1. Preparation of electrode A water-soluble binder (commercially available CMC) and acetylene black were mixed with each of the electrode materials of Examples or Comparative Examples so that the electrode material: CMC: acetylene black = 8: 1: 1 (mass ratio). Further, it was made into a paste, applied to the surface of the aluminum foil, and dried to produce a sheet-like electrode. The thickness of the coating layer after drying was 80 μm. Next, the aluminum was punched into a circle with a diameter of 25.4 mm, and this was pressed at 77 MPa to produce an electrode.

2. Assembling the capacitor After drying the electrode under vacuum conditions at 200 ° C. for 1 hour, the electrode was charged with an electrolyte (a propylene carbonate solution containing 1 mol / L of tetraethylammonium tetrafluoroborate) in a glove box in which nitrogen gas was circulated. Was vacuum impregnated. This electrode was sandwiched between polypropylene separators impregnated with electrolytic solution (Celgard “Celguard # 3501”), and further sandwiched between aluminum plates to assemble a capacitor.

(Capacitor electrode density)
The density of the electrode was calculated by dividing the total mass of the first activated carbon, second activated carbon, carboxymethyl cellulose, acetylene black, and polytetrafluoroethylene used in preparing the electrode material by the volume of the electrode material layer. .

(Capacitance of the capacitor)
Connect the charge / discharge terminal of the charge / discharge device ("ACD-01" manufactured by Asuka Electronics Co., Ltd.) to the aluminum plate of the capacitor, and charge at 20mA at -30 ° C until the voltage between the current collector plates reaches 2.5V. Then, the battery was charged with a constant voltage of 2.5 V for 5 minutes. After charging, the capacitor was discharged with a constant current (discharge current = 0.015 A). The capacitance of the capacitor was determined from the discharge curve between 2.0 and 1.0V. Then, the mass-based capacitance (unit: F / g) is calculated by dividing the capacitance of the capacitor by the total mass of the first activated carbon and the second activated carbon, and the capacitance of the capacitor is calculated as the electrode material layer in the electrode. The volume-based capacitance (unit: F / ml) was calculated by dividing by the total volume.

(Internal resistivity of capacitor)
After charging the capacitor under the same conditions as the evaluation of the capacitance, the capacitor was discharged with a constant current (discharge current = 0.015 A). The internal resistivity was determined from the voltage drop immediately after the start of discharge. That is, a voltage gradient is derived from each measured voltage between 0.5 and 2.0 seconds after the start of discharge, a voltage at the start of discharge is obtained from this voltage gradient, and the voltage, charge voltage (2.5 V), and voltage difference Asked. The internal resistivity (unit: Ω · m) of the capacitor was calculated from the voltage difference, the discharge current, the thickness of the electrode material layer, and the area of the electrode material.

  The calculation results of the specific surface area, pore volume, electrode density, capacitance, and internal resistivity are shown in Tables 1 to 3.

  Moreover, the graph (graph based on the data of Example 1a, Example 2b, Example 3a, and Comparative Examples 1-3) showing the correlation between the average particle diameter of the first activated carbon and the internal resistivity of the capacitor is shown in FIG. And a graph showing the correlation between the average particle diameter of the first activated carbon and the capacitance of the capacitor (a graph based on data of Example 1a, Example 2b, Example 3a, and Comparative Examples 1 to 3). 2 is a graph showing the correlation between the added amount of the first activated carbon and the internal resistivity of the capacitor (data of Examples 1a to 1b, Examples 2a to 2d, Examples 3a to 3b, and Comparative Examples 1 to 3) FIG. 3 shows a graph based on the above.

  From the graph shown in FIG. 1 and Table 1 (Examples 1a, 2b, 3a, Comparative Examples 1 to 3), when the average particle size of the first activated carbon is decreased, the internal resistivity of the capacitor is decreased, and the average particle size is 1.0 μm. In the following, it can be confirmed that the decrease in internal resistivity started to increase, and that the decrease in internal resistivity was further increased at an average particle size of 0.8 μm or less. Further, from the graph shown in FIG. 2 and Table 3 (Examples 1a, 2b, 3a, Comparative Examples 1 to 3), even if the first activated carbon having an average particle size of 1.0 μm is used, the capacitance is small. If the first activated carbon having an average particle size of less than 1.0 μm is used, it can be confirmed that the capacitance has increased.

  Further, from the comparison between all examples and all comparative examples in Table 1, when the first activated carbon having an average particle size of 1.0 μm or less is used, it is irrelevant to the type of the first activated carbon raw material and the activation method. It can be confirmed that the internal resistivity decreased and the capacitance increased. This tendency is the same even if the second activated carbon is changed (see Table 2).

  From the graph shown in FIG. 3 and Table 3 (Examples 1a to 1b, Examples 2a to 2d, Examples 3a to 3b, and Comparative Examples 1 to 3), the first activated carbon having an average particle size of 1.0 μm or less is used. In this case, it can be confirmed that the internal resistivity of the capacitor tended to decrease as the amount of use increased.

It is a graph showing the correlation with the average particle diameter of the 1st activated carbon of the Example which concerns on this invention, and the internal resistivity of a capacitor. It is a graph showing the correlation with the average particle diameter of the 1st activated carbon of the Example which concerns on this invention, and the electrostatic capacitance of a capacitor. It is a graph showing the correlation with the addition amount of the 1st activated carbon of the Example which concerns on this invention, and the internal resistivity of a capacitor.

Claims (6)

  An electrode material for an electric double layer capacitor in which a first activated carbon having an average particle diameter of 1 μm or less and a second activated carbon having an average particle diameter exceeding 1 μm are mixed.   2. The electrode material for an electric double layer capacitor according to claim 1, wherein the average particle diameter of the first activated carbon is 0.8 μm or less.   3. The electrode material for an electric double layer capacitor according to claim 1, wherein the average particle diameter of the first activated carbon is 0.5 μm or less.   The electrode for electric double layer capacitors manufactured using the electrode material for electric double layer capacitors of any one of Claims 1-3.   The electric double layer capacitor manufactured using the electrode for electric double layer capacitors of Claim 4. The additive for electrode materials used for the electrode material for electric double layer capacitors which has the 1st activated carbon with an average particle diameter of 1 micrometer or less, and the 2nd activated carbon with an average particle diameter exceeding 1 micrometer is mixed.

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