JP2010073793A - Electrode for electrical double-layer capacitor and electrical double-layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a novel polarized electrode which improves manufacturing efficiency, particularly in a rolling sheet process of the polarized electrode using a carbon material which has graphite-like microcrystalline carbon. <P>SOLUTION: The electrode is the sheet-like electrode for an electrical double layer capacitor which contains: the carbon material which has the graphite-like microcrystalline carbon; and a binder wherein the average sphericity (X-axis Y-axis aspect ratio) of the carbon material by a flow type image analysis method is 0.65 or larger. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrode for an electric double layer capacitor and an electric double layer capacitor.

  In recent years, electric double layer capacitors that can be charged and discharged with a large current are promising as power storage devices with high charge / discharge frequency, such as an auxiliary power source for electric vehicles, an auxiliary power source for solar cells, and an auxiliary power source for wind power generation. Therefore, an electric double layer capacitor having a high energy density, capable of rapid charge / discharge, and excellent in durability is desired.

  The electric double layer capacitor has a structure in which a pair of polarizable electrodes are opposed to each other with a separator interposed therebetween to form a positive electrode and a negative electrode. Each polarizable electrode is impregnated with an aqueous electrolyte solution or a non-aqueous electrolyte solution, and each polarizable electrode is joined to a collector electrode.

Since the energy stored in the electric double layer capacitor is proportional to the square of the voltage, it is preferable to operate at the highest possible voltage. However, the conventional activated carbon has a very large specific surface area of about 1000 to 3000 m ² / g, and the surface has many functional groups such as —OH and —COOH generated at the time of activation of 0.3 eq / g or more. Since the withstand voltage of these functional groups is low, when a voltage of about 2 V is applied, it decomposes and generates H ₂ O, CO _2, etc., and when this is incorporated in the electrode, it causes deterioration of the capacitor. In particular, it was impossible to produce a capacitor having a long life by applying a high voltage of about 3V.

As a polarizable electrode material used for an electric double layer capacitor, a non-porous carbon material having graphite-like microcrystalline carbon is known (Patent Documents 1 to 9). This carbon material is prepared so that the interlayer distance of the crystallites of microcrystalline carbon similar to graphite is within the range of 0.350 to 0.385 nm by controlling the activation treatment of the raw material. Microcrystalline carbon having such a specific interlayer distance has a low specific surface area because it has a small specific surface area (about several hundred m ² / g) even when a normally used voltage is applied in contact with the electrolyte solution. Only a capacitance can be obtained, but once a high voltage exceeding the voltage used once is applied, electrolyte ions are inserted between the layers, and as a result, a high capacitance is exhibited. This carbon material maintains a high capacitance even if it is repeatedly used at a normally used voltage (2.8 to 4.0 V) after that, once ions are inserted. This carbon material has attracted attention as a carbon material that can replace activated carbon because it has a higher withstand voltage and significantly higher energy density than activated carbon generally used as a carbon material for electric double layer capacitors. ing.

JP 11-317333 A JP 2000-068165 A JP 2000-068164 A JP 2000-077273 A Japanese Patent Laid-Open No. 2000-1000066 JP 2002-025867 A JP 2002-083747 A JP 2003-051430 A JP 2003-086469 A

  As a method for manufacturing an electrode of an electric double layer capacitor, there are a coating manufacturing method in which an electrode material is coated on a current collector and a sheet manufacturing method in which the electrode material is rolled. Compared with the sheet manufacturing method, the coating manufacturing method can easily reduce the thickness of the electrode, but the electrode density is low, so that it is not suitable for applications requiring a high energy density. On the other hand, the sheet manufacturing method is produced by rolling the electrode material itself, so the thinner the sheet by rolling, the higher the density of the electrode and the higher the energy density, so graphite-like microcrystalline carbon It is suitable for producing a high energy density electrode using a carbon material having However, a carbon material having graphite-like microcrystalline carbon has a structure in which graphene structures are laminated relatively in parallel, and thus is often formed into elongated rod-like particles unlike general activated carbon. If an electrode is produced by rolling using such a carbon material containing a large amount of rod-like particles, the fluidity of the carbon material particles is low and the formability of the sheet is extremely poor. For this reason, in order to make it a desired thickness by a sheet manufacturing method, it is necessary to repeat a rolling process many times, and manufacturing efficiency is very low.

  Accordingly, an object of the present invention is to provide a novel polarizable electrode that improves the production efficiency of a polarizable electrode using a carbon material having microcrystalline carbon similar to graphite, particularly in a rolled sheet manufacturing method.

According to the present invention,
(1) A sheet-like electrode for an electric double layer capacitor comprising a carbon material having microcrystalline carbon similar to graphite and a binder, wherein the average sphericity of the carbon material by a flow image analysis method (X An electrode is provided in which the aspect ratio (axis Y-axis aspect ratio) is 0.65 or more.

Furthermore, according to the present invention,
(2) The electrode according to (1) is provided, wherein the electrode is formed into a sheet by rolling.

Furthermore, according to the present invention,
(3) The electrode according to (1) or (2), wherein the equivalent circle diameter of the carbon material is 5 μm or more.

Furthermore, according to the present invention,
(4) The electrode according to any one of (1) to (3), wherein the carbon material has a specific surface area of 200 m ² / g or less.

Furthermore, according to the present invention,
(5) The electrode according to any one of (1) to (4), wherein an interlayer distance d _{002 of the} carbon material by an X-ray diffraction method is in a range of 0.350 to 0.385 nm. .

Furthermore, according to the present invention,
(6) The electrode according to any one of (1) to (5), wherein the carbon material is obtained from a pitch-based carbon precursor.

Furthermore, according to the present invention,
(7) The electrode according to any one of (1) to (6), wherein the binder is polytetrafluoroethylene (PTFE).

Furthermore, according to the present invention,
(8) The electrode according to any one of (1) to (7), further including a conductive auxiliary material.

Furthermore, according to the present invention,
(9) The electrode according to any one of (1) to (8), wherein the electrode has a thickness of 400 μm or less.

Furthermore, according to the present invention,
(10) An electric double layer capacitor including the electrode according to any one of (1) to (9) is provided.

Furthermore, according to the present invention,
(11) The method for producing an electrode for an electric double layer capacitor according to any one of (1) to (9), wherein the carbon material is heat-treated within a range of 400 to 600 ° C, There is provided a method characterized in that the spheronization treatment is performed by a high-speed in-air impact method.

Furthermore, according to the present invention,
(12) A carbon material for an electric double layer capacitor electrode having microcrystalline carbon similar to graphite, and having an average sphericity (X-axis Y-axis aspect ratio) of 0.65 or more by a flow image analysis method. A characteristic carbon material is provided.

Furthermore, according to the present invention,
(13) The carbon material according to (12), wherein the equivalent circle diameter is 5 μm or more.

Furthermore, according to the present invention,
(14) The carbon material according to (12) or (13), wherein the specific surface area is 200 m ² / g or less.

Furthermore, according to the present invention,
(15) an interlayer distance d ₀₀₂ by X-ray diffraction method is within the range of 0.350~0.385nm, (12) a carbon material according to any one of - (14) are provided.

Furthermore, according to the present invention,
(16) The carbon material according to any one of (12) to (15), which is obtained from a pitch-based carbon precursor.

Furthermore, according to the present invention,
(17) The method for producing a carbon material for an electric double layer capacitor electrode according to any one of (12) to (16), wherein the material of the carbon material is within a temperature range of 400 ° C to 600 ° C. There is provided a method characterized by heat-treating and then spheronizing by a high-speed air current impact method.

  According to the present invention, a carbon material having microcrystalline carbon similar to graphite can be obtained by using a carbon material having an average sphericity (X-axis Y-axis aspect ratio) of 0.65 or more according to a flow image analysis method. The production efficiency of the polarizable electrode used in the method for producing a rolled sheet is improved. Furthermore, surprisingly, the use of the carbon material according to the present invention improves the durability of the electric double layer capacitor.

  An electrode for an electric double layer capacitor according to the present invention is a sheet-like electrode for an electric double layer capacitor comprising a carbon material having microcrystalline carbon similar to graphite and a binder, and a flow image of the carbon material. The average sphericity (X-axis Y-axis aspect ratio) by the analysis method is 0.65 or more. The electric double layer capacitor electrode according to the present invention is particularly preferably formed into a sheet by rolling.

The average sphericity (X-axis Y-axis aspect ratio) is a parameter indicating the degree of sphericity, and the maximum particle length (by flow image analysis method using a flow particle image analyzer “FPIA-3000” manufactured by Sysmex Corporation). It is an average value of aspect ratios obtained from the following formula from the X axis) and the maximum length vertical length (Y axis).
Aspect ratio = (Maximum vertical length) / (Maximum length)
The upper limit of the aspect ratio is 1, which means that the particle is a perfect sphere. When the average sphericity of the carbon material according to the present invention is less than 0.65, the fluidity of the carbon material particles becomes insufficient particularly during the rolling process, and the formability of the electrode sheet is deteriorated. The carbon material according to the present invention preferably has an average sphericity of 0.68 or more, and more preferably 0.70 or more.

  The carbon material according to the present invention preferably has an equivalent circle diameter of 5 μm or more, and more preferably 10 μm or more. When the carbon material according to the present invention has an equivalent circle diameter of less than 5 μm, fixing with a binder described later becomes insufficient, and the electrode is likely to deteriorate. On the contrary, if the equivalent circle diameter is 20 μm or more, the top particle diameter may be more than the thickness of the electrode, which is not preferable.

The carbon material according to the present invention (hereinafter also referred to as “graphite-like carbon material”) has microcrystalline carbon similar to graphite. Since this graphite-like carbon material has a small specific surface area, it is not suitable as an electrode for an electric double layer capacitor from the conventional standard in which activated carbon is used. However, when the interlayer distance d ₀₀₂ (by X-ray diffraction method) of the microcrystalline carbon is in a specific range, that is, 0.350 to 0.385 nm, this carbon material has a small specific surface area. High capacitance as a polarizable electrode. When the interlayer distance d ₀₀₂ is in the range of 0.365～0.380Nm, more preferable because expression of capacitance due to insertion into the interlayer of the electrolyte ions conspicuous. When the interlayer distance d ₀₀₂ is below 0.350 nm, since the insertion into the interlayer of the electrolyte ions becomes difficult to occur, the electrostatic capacitance decreases. Even if the interlayer distance d ₀₀₂ in the opposite is more than 0.385, the capacitance hardly occur inserted into the interlayer of the electrolyte ions decreases undesirably.

Carbon material according to the present invention has a specific surface area is preferably in the range of 20 to 200 m ² / g, further more preferably in the range of 50 to 150 m ² / g. When this specific surface area exceeds 200 m ² / g, the amount of functional groups present on the surface of the graphite-like carbon material increases, and the performance degradation of the electric double layer capacitor due to the decomposition of these functional groups when a voltage is applied is marked. Become. The specific surface area is a value measured by a BET 1-point method using “MONOSORB” manufactured by Yuasa Ionics Co., Ltd. (drying temperature: 180 ° C., drying time: 1 hour).

  The graphite-like carbon material is contained in the electrode in the range of 50 to 99% by mass, preferably 65 to 95% by mass, based on the total mass of the conductive auxiliary material and binder described later. When the content of the graphite-like carbon material is less than 50% by mass, the energy density of the electrode is lowered. On the other hand, if the content exceeds 99% by mass, the binder is insufficient and a continuous sheet-like electrode cannot be formed.

  When used as an electrode for an electric double layer capacitor, the graphite-like carbon material exhibits a high capacitance and a characteristic of expanding when a voltage is applied. That is, when a graphite-like carbon material is formed into a sheet shape and an electric double layer capacitor in which the current collector is laminated on one or both sides is assembled and a voltage is applied between the current collectors, the graphite-like carbon material is It exhibits the characteristic of expanding mainly in the direction of voltage application by both current collectors. When the graphite-like carbon material used as the electrode expands, the volume of the electric double layer capacitor increases. Therefore, even if the capacitance of the capacitor increases, the capacitance of the electric double layer capacitor per unit volume increases. It is diminished accordingly. Therefore, in order to enjoy the increase in capacitance, it is preferable to minimize the increase in volume of the electric double layer capacitor due to the expansion of the graphite-like carbon material. In order to suppress the increase in volume of the electric double layer capacitor, a pressure that resists the pressure (expansion pressure) generated by the expansion of the graphite-like carbon material may be applied to the electrode from the outside. In fact, even if the volume expansion of the electrodes is completely suppressed, the capacitance generated between the electrodes is not different from the case where free expansion is allowed.

  The carbon material according to the present invention can be prepared as follows. First, various materials such as wood, fruit shells, coal, pitch and coke used as activated carbon raw materials are heat-treated (primary at a temperature in the range of 400 to 600 ° C., preferably 450 to 550 ° C. in an inert atmosphere. Bake). It should be noted that this primary firing should be a heat treatment at a relatively low temperature in order to promote a spheronization treatment by a high-speed air current impact method described later. Next, the above-described equivalent circle diameter is adjusted by pulverizing the solidified primary baked carbon material by, for example, an airflow pulverization method. Thereafter, spheronization is performed by the impact method in high-speed airflow until the average sphericity becomes 0.65 or less. For example, a hybridization system (NHS) commercially available from Nara Machinery Co., Ltd. is convenient for carrying out the high-speed air current impact method. According to the hybridization system, mechanical thermal energy mainly composed of impact force is applied to the particles while dispersing the carbon material particles in the gas phase, and the rod-shaped particles are rounded to form a sphere. Further, the carbonized carbon material is carbonized by heat treatment (secondary firing) at a temperature of 700 ° C. to 1000 ° C. Thereafter, an activation treatment is performed at a temperature of about 800 ° C. in an inert atmosphere using an alkali such as potassium hydroxide. For details of the processing steps other than the spheroidizing treatment of the graphite-like carbon material suitably used in the present invention, see Patent Documents 1 to 9.

  The electrode according to the present invention preferably contains a conductive auxiliary material. As the conductive auxiliary material, carbon black such as ketjen black and acetylene black, nanocarbon such as fullerene, carbon nanotube, and carbon nanohorn, powder graphite, and the like can be used. The conductive auxiliary material may be added in an amount of preferably 1 to 40% by mass, more preferably 3 to 20% by mass, based on the total mass of the graphite-like carbon material and the binder. When the addition amount of the conductive auxiliary material is less than 1% by mass, the internal resistance of the electric double layer capacitor is increased. On the contrary, when the addition amount exceeds 40% by mass, the energy density of the electrode is lowered.

  The electrode according to the present invention contains a binder for binding a graphite-like carbon material and a conductive auxiliary material into a sheet. As the binder, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene (PE), polypropylene (PP), styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), or the like can be used. The binder may be added in an amount of preferably 1 to 30% by mass, more preferably 3 to 20% by mass, based on the total mass of the graphite-like carbon material and the conductive auxiliary material. If the amount of the binder added is less than 1% by mass, a continuous sheet-like electrode cannot be formed. On the contrary, when the addition amount exceeds 30% by mass, the internal resistance of the electric double layer capacitor is increased.

  The electrode according to the present invention can be produced by the same method as in the case of using conventional activated carbon. For example, after adding a conductive auxiliary material and a binder to the graphite-like carbon material obtained by the above-mentioned method and kneading, it can be preferably formed into a sheet by a rolling process. In kneading, liquid auxiliaries such as water, ethanol, acetonitrile, siloxane and the like may be used alone or in combination as appropriate. The graphite-like carbon material spheroidized according to the present invention has high fluidity and moves smoothly especially during rolling. Therefore, the number of rolling processes required to obtain a desired thickness, for example, 400 μm or less is greatly reduced, and the electrode manufacturing efficiency is dramatically improved.

  The thickness of the electrode according to the present invention is preferably 400 μm or less, and more preferably in the range of 100 to 150 μm. If this thickness is less than 100 μm, pinholes are likely to occur in the electrode. On the other hand, if it exceeds 400 μm, the density of the electrode cannot be increased, so that the energy density of the electrode is lowered.

  An electric double layer capacitor according to the present invention is assembled by combining a sheet-like electrode according to the present invention with an appropriate current collector and separator generally used for electric double layer capacitors, and impregnating the electrode with an appropriate electrolyte. Can do. As the current collector, various sheet materials including metal sheets such as aluminum, titanium and stainless steel, and nonmetal sheets such as conductive polymer films and conductive filler-containing plastic films can be used. . The sheet-like current collector may have a hole in part or the entire surface. The sheet-like electrode and the current collector can function by simply crimping them together, but in order to reduce the contact resistance between them, the electrode and the current collector can be joined using a conductive paint as an adhesive. Alternatively, the electrode and the current collector may be pressure-bonded after the conductive paint is applied to the electrode or the current collector and dried. As the separator, an insulating material such as microporous paper, glass, or a plastic porous film such as polyethylene, polypropylene, or polytetrafluoroethylene can be used. The thickness of the separator is generally about 10 to 100 μm. As the electrolytic solution, a liquid electrolyte may be used, or an electrolyte solution in which the electrolyte is dissolved in an organic solvent may be used. For specific examples of the electrolytic solution, refer to JP-A-2004-289130.

  The electric double layer capacitor assembled in this way is charged by applying a voltage 3 to 100% higher than the voltage to be used (usually about 3.0 to 4.2 V), so that the electrolyte ions (of the organic solvent) It is inserted into the structure of the graphite-like carbon material (with a solvent in the presence) and then forms an electric double layer.

Hereinafter, the present invention will be specifically described by way of examples.
Example 1
The pitch-based carbon precursor was fired in an inert atmosphere at a temperature of 450 ° C. to produce a primary fired product. The primary baked carbon material was treated for 10 minutes at a rotation speed of 4000 rpm using a hybridization NHS-3 type manufactured by Nara Machinery Co., Ltd. to obtain a spheroidized carbon material having an average sphericity of 0.72. Then, using a carbonized material obtained by firing and carbonizing the spheroidized carbon material again at a temperature of 800 ° C., this was mixed with twice the amount of potassium hydroxide in a mass ratio, and an activation treatment was performed at 800 ° C. in an inert atmosphere. A graphite-like carbon material having a BET specific surface area of 125 m ² / g was prepared. The graphite-like carbon material, the interlayer distance d ₀₀₂ by X-ray diffraction of the microcrystalline carbon in the range of up to 0.360 nm. 80% by mass of this graphite-like carbon material, 10% by mass of Ketjen black powder (“EC600JD” manufactured by Ketjen Black International Co., Ltd.) as a conductive auxiliary material, and polytetrafluoroethylene powder (manufactured by Mitsui Dupont Fluoro Chemical Co., Ltd.) as a binder Ethanol was added to a mixture of 10% by mass of “Teflon (registered trademark) 6J”) and kneaded, and then roll rolling was performed three times to obtain a polarizable sheet having a width of 100 mm and a thickness of 200 μm. A high-purity etched aluminum foil (“C512” manufactured by KDK Corporation) having a width of 150 mm and a thickness of 50 μm is used as a current collector, and a conductive adhesive solution (“GA-37” manufactured by Hitachi Powdered Metallurgy Co., Ltd.) is provided on both sides thereof. Was applied with 30 g / m ² by an application roll. This coating amount is 6 g / m ² in terms of dry mass. After the application, the above long polarizable sheet was superimposed on the application part (both sides) of the current collector, and this was pressed through a compression roll to obtain a laminated sheet in which the contact interfaces were securely bonded together. The laminated sheet was passed through a continuous hot air dryer set at a temperature of 150 ° C., and the dispersion medium was evaporated and removed from the conductive adhesive liquid layer to obtain a long polarizable electrode. The passing speed in the dryer was a speed at which all portions of the laminated sheet stayed in the dryer for 3 minutes.

  In this long sheet-like laminated sheet, the size of the carbon electrode portion of the polarizable electrode is 10 cm square, and the lead portion (the portion where the polarizable electrode is not laminated on the current collector) is 2 × 10 cm. A rectangular polarizable electrode was punched out. A single cell was fabricated by inserting one sheet of ePTFE sheet (“BSP07008070” manufactured by Japan Gore-Tex Co., Ltd.) having a thickness of 80 μm between the two polarizable electrode bodies as a positive electrode and a negative electrode. Next, the single cell was vacuum-dried at 230 ° C. for 24 hours, and then housed in an aluminum pack in a glove box maintained at −60 ° C. or lower in an argon atmosphere. The aluminum pack was cut from “PET12 / Al20 / PET12 / CPP30 dry laminate product” made by Showa Denko Packaging Co., Ltd. and fused into a 25 × 20 cm bag (one short side opened, other Three sides were fusion sealed. The electrode was impregnated with the electrolytic solution under a reduced pressure of −0.05 MPa, and a 1.8 mol / L propylene carbonate solution of triethylmethylammonium tetrafluoroborate as an electrolytic solution was poured into the aluminum pack and left to stand for 10 minutes. went. Finally, a square electric double layer capacitor was manufactured by fusing and sealing the opening of the aluminum pack. The intended use voltage of this capacitor is 3.3V.

The square electric double layer capacitor was stored at 25 ° C. for 24 hours. Thereafter, the capacitor was pressurized with a pressing force (surface pressing force) of 2.45 × 10 ⁶ Pa from both sides of the capacitor, and in this pressurized state, the initial charge was 5 mA / cm ² in a constant temperature bath of 40 ° C. The battery was charged to 3.5 V at a current density, and then discharged to 0 V at the same current density. This capacitor was referred to as Example 1.

Examples 2-5
It was produced in the same manner as in Example 1 except that it was produced by changing the treatment rotation speed and treatment time in the hybridization apparatus as shown in Table 1.

Examples 6 and 7
It was produced in the same manner as in Example 1 except that the pitch-based carbon precursor was produced by changing the temperature when firing in an inert atmosphere as shown in Table 1.

Examples 8-10
It was produced in the same manner as in Example 1 except that the activation treatment conditions were changed and the specific surface area was changed as shown in Table 1.

Comparative Example 1
It was produced in the same manner as in Example 1 except that the spheroidizing treatment was not performed before firing and activating the pitch-based carbon precursor in an inert atmosphere.

For the electric double layer capacitors of Examples 1 to 10 and Comparative Example 1, volume capacitance density and internal resistance, electrode expansion coefficient, and durability performance were measured. The measurement conditions are as follows. As an index of electrode processability, it was judged as the thickness that can be thinned most by our manufacturing method.
(Volume capacitance density)
Measuring instrument: “CDT510-4” manufactured by Power System Co., Ltd.
Temperature: 20 ° C
Charge: 5 mA / cm ² , 3.3 V, 3600 seconds Discharge: 5 mA / cm ² , 0 V
The capacitance at the fifth cycle was determined by an energy conversion method, and calculated by dividing the capacitance by the volume of the positive and negative carbon electrode parts not including the current collector after expansion. Analysis software (“CDT Utility” manufactured by Power System Co., Ltd.) was used for the calculation.
(DC internal resistance)
At the time of measuring the volume capacitance density, V = IR was calculated. Analysis software (“CDT Utility” manufactured by Power System Co., Ltd.) was used for the calculation.
(Expansion rate)
The electrode part thickness (thickness measured by removing the surface pressure) after charging in the fifth cycle under the charge / discharge conditions described later was calculated by dividing by the initial thickness of 200 μm (100% is unchanged).
(Durability)
For the electric double layer capacitor described above, an operation of charging at 5 mA / cm ² at a temperature of 45 ° C. for 1 hour at 3.3 V and discharging until reaching 0 V at 5 mA / cm ² was performed as one cycle, After confirming the capacity and direct current resistance, float charging was performed under the same conditions for 1000 hours, and the electrostatic capacity and direct current resistance were confirmed every 20 hours. The capacitance at the first cycle and after 1000 hours is obtained by the above-described method for the capacitance density, and the result is the retention rate of capacitance at the time when 1000 hours have elapsed with respect to the measurement start time (first cycle) [100 × (Capacitance of cycle after elapse of 1000 hours) / (Capacitance of first cycle)] (%) The internal resistance was similarly calculated.

  As can be seen from Table 2, the capacitor electrode of each example according to the present invention can be made thinner than the untreated comparative electrode when the electrode is produced by our manufacturing method. That is, the electrode processability was very good. This is considered to be because the aspect ratio of the particles was improved by applying the spheroidizing treatment, and the fluidity of the particles was improved and the electrode processability was improved by becoming closer to a spherical shape.

  Although the volume capacitance density and DC resistance are the same as those of the comparative example, the durability performance and the DC resistance increase rate after 1000 hours are superior to the capacitor using the untreated comparative electrode. It was.

Claims (17)

  A sheet-like electrode for an electric double layer capacitor comprising a carbon material having microcrystalline carbon similar to graphite and a binder, wherein the average sphericity (X axis and Y axis) of the carbon material by a flow image analysis method An electrode having an aspect ratio of 0.65 or more.   The electrode according to claim 1, wherein the electrode is formed into a sheet by a rolling process.   The electrode according to claim 1, wherein the equivalent circle diameter of the carbon material is 5 μm or more. The electrode according to any one of claims 1 to 3, wherein the carbon material has a specific surface area of 200 m ² / g or less. Interlayer distance d ₀₀₂ by X-ray diffractometry of the carbon material is within the range of 0.350～0.385Nm, electrode according to any one of claims 1 to 4.   The electrode according to any one of claims 1 to 5, wherein the carbon material is obtained from a pitch-based carbon precursor.   The electrode according to claim 1, wherein the binder is polytetrafluoroethylene (PTFE).   Furthermore, the electrode of any one of Claims 1-7 containing a conductive support material.   The electrode according to claim 1, wherein the electrode has a thickness of 400 μm or less.   The electric double layer capacitor containing the electrode of any one of Claims 1-9.   It is a manufacturing method of the electrode for electric double layer capacitors of any one of Claims 1-9, Comprising: The raw material of the said carbon material is heat-processed within the range of 400-600 degreeC, Then, the impact method in a high-speed airflow A spheronization process according to claim 1.   A carbon material for an electric double layer capacitor electrode having microcrystalline carbon similar to graphite, characterized in that an average sphericity (X-axis Y-axis aspect ratio) by a flow image analysis method is 0.65 or more. Carbon material.   The carbon material according to claim 12, wherein the equivalent circle diameter is 5 μm or more. The carbon material according to claim 12 or 13, wherein the specific surface area is 200 m ² / g or less. Interlayer distance d ₀₀₂ by X-ray diffraction method is within the range of 0.350～0.385Nm, carbon material according to any one of claims 12 to 14.   The carbon material according to any one of claims 12 to 15, which is obtained from a pitch-based carbon precursor.   It is a manufacturing method of the carbon material for electric double layer capacitor electrodes of any one of Claims 12-16, Comprising: The raw material of the said carbon material is heat-processed within the range of the temperature of 400 to 600 degreeC, Then, it is high-speed. A method characterized in that spheronization treatment is performed by an impact-in-air method.