Activated carbon for electric double-layer capacitor electrode, and method for producing the same

The present invention relates to activated carbon for electric double layer capacitor electrodes and a method for producing the same.

Activated carbon has a porous structure by activating carbonized carbon materials such as carbonized coconut husk, petroleum coke, and coal coke. Porous activated carbon having a large surface area is often used as an adsorbent, a catalyst carrier, an electric double layer capacitor, an electrode material such as a lithium secondary battery, and the like. In particular, in an electric double layer capacitor used for a hybrid car or the like, in order to increase the energy density, that is, the capacitance, micropores are effectively formed as the electrode material, and the degree of crystallization is high and the surface area is large. Large activated carbon is required.

For the industrial production of activated carbon in which fine pores that can be used as the electrode material of such an electric double layer capacitor are effectively formed, a carbon material such as petroleum coke and an alkali metal compound such as potassium hydroxide are used in an inert gas atmosphere. For example, an activation method in which an alkali metal is allowed to penetrate between graphite crystal layers and reacted by heating in a range of 600 to 1200 ° C. is generally used (Patent Document 1). In such activation, the alkali metal penetrates into the layered structure in which the layered condensed polycyclic carbon compound is laminated, and micropores are formed. In the method of producing activated carbon for electric double layer capacitor electrodes by activating a carbon material as a raw material with an alkali activator, the activator is usually used by mixing 2 to 4 times the weight ratio with respect to the carbon material. In particular, the target specific surface area value is 2000 to 3000 m.²If it is as large as / g, increase the "activator / carbon material" ratio. However, since the alkali activator accounts for a large proportion of the manufacturing cost, it is desired to reduce the proportion of the alkaline activator used as much as possible.

In the mixing of carbon material and alkali activator, since the carbon material is water repellent, the wettability with the water-soluble alkali activator is poor, and simply mixing the two types causes contact between the activator and the carbon material. Since it is insufficient, most of the activators are not used in the activation reaction, and the specific surface area of the obtained activator (activated carbon) is small. Therefore, as a means for strongly contacting them, a method of mechanically mixing such as a ball mill or a Henschel mixer, a method of melting an alkali activator and mixing, and the like are known (Patent Document 2). However, in either method, in order to proceed with the activation reaction more efficiently, it is necessary to use more activator than the theoretical amount, which is a factor of cost increase.

<p><patcit num="1"><text>Japanese Unexamined Patent Publication No. 2006-059923</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2002-134369</text></patcit></p>

<p> In response to the above problems, the present inventors improve the contact efficiency between the carbon material and the activator by improving the wettability of the carbon material with the alkaline activator, and make the reaction between the raw material carbon material and the activator efficient. Various studies were conducted based on the idea that it can be advanced in a targeted manner. As a result, an oxidized product obtained by oxidizing a carbon powder obtained by adjusting the particle size of a carbon material to an average particle size in the range of 0.5 μm to 15 μm so that the oxygen content is 3% by mass or more is obtained. The wettability with the alkaline activator can be greatly improved, and by using such an oxidation-treated product, the contact efficiency with the alkaline activator is improved, and the portion left unactivated by the conventional method is also activated. Therefore, it has been found that activated carbon having a remarkably large specific surface area can be obtained, and the present invention has been completed. That is, according to the present invention, when activated carbon having the same specific surface area as before is produced, not only can it be activated with a small amount of activator, but also the activation reaction proceeds uniformly, which is superior to the conventional case. Activated carbon is obtained.</p>

<p> That is, in the present invention, the carbon powder obtained by adjusting the particle size of the carbon material as it is or by calcining it to an average particle size in the range of 0.5 μm to 15 μm is oxidized so that the oxygen content is 3% by mass or more. The present invention relates to a method for producing activated carbon for an electric double layer capacitor electrode, which comprises activating the obtained oxidation-treated product with an alkali activator.</p><p> The present invention also relates to the above-described method for producing activated carbon, which is characterized in that the carbon material is graphitizable. The present invention also relates to the above-described method for producing activated carbon, wherein the firing treatment temperature is in the range of 500 ° C to 900 ° C. Further, the present invention is characterized in that the mixing ratio of the oxidized product and the alkali activator is in the range of the oxidized product: alkali activator = 1: 1 to 1: 4 (mass ratio). Regarding the manufacturing method of.</p><p> The present invention also relates to activated carbon for electric double layer capacitor electrodes obtained by the production method described above. Furthermore, the present invention relates to an electric double layer capacitor using the above-mentioned activated carbon as an electrode.</p>

<p> According to the present invention, the reaction between the carbon material and the alkali activator can proceed extremely efficiently, and as a result, the amount of the alkali activator used can be reduced as compared with the conventional case, and the manufacturing cost can be significantly reduced. Further, according to the method of the present invention, activated carbon having excellent uniformity can be obtained, and by using it as an electrode of an electric double layer capacitor, activated carbon having a large capacitance per unit volume can be provided.</p>

<figref num="1">The configuration of the laminate cell used for evaluating the carbon electrode material is shown.</figref><figref num="2">The method of measuring the initial characteristics (capacitance, internal resistance) of a capacitor is shown.</figref>

Hereinafter, the present invention will be described in detail. As the carbon material used as a starting material in the present invention, a graphitizable carbon material is preferably used. Examples of the graphitizable carbon material include petroleum coke and coal coke, and examples thereof include mesophase pitch and infusible and carbonized mesophase pitch fibers spun from the mesophase pitch. Of these, petroleum coke is preferred.

Petroleum coke is a product mainly composed of solid carbon obtained by pyrolyzing (coking) the heavy distillate of petroleum at a high temperature of about 500 ° C. Call. There are two types of petroleum coke, one is by the delayed caulking method and the other is by the fluid caulking method, and the former is currently the majority. In the present invention, it is preferable to use raw petroleum coke (raw coke) which is in a state of being taken out from the coke with this petroleum coke. Raw coke produced by the delayed coking method usually has a volatile content of 6 to 13% by mass, and raw coke produced by the fluid coking method usually has a volatile content of 4 to 7% by mass. In the present invention, raw coke by any method may be used, but raw coke produced by the delayed coking method, which is easily available and has stable quality, is particularly preferable.

The heavy fraction of the above petroleum is not particularly limited, but heavy oil obtained as residual oil when petroleum is distilled under reduced pressure, heavy oil obtained when petroleum is cracked by fluidized contact, and petroleum are used. Examples thereof include heavy oil obtained by hydrodesulfurization and a mixture thereof.

In the present invention, (1) the carbon material is adjusted in particle size and then oxidized, and then mixed with an alkali activator to carry out an activation reaction, or (2) the carbon material is calcined and then the particle size is adjusted. After adjustment, oxidation treatment is performed, and then the mixture is mixed with an alkaline activator to carry out an activation reaction.

When the carbon material is fired, it is preferably carried out in an inert gas in a temperature range of 500 to 900 ° C, more preferably 500 to 800 ° C. At that time, there is no particular limitation on the rate of temperature rise, but if it is too slow, the treatment process will take time, and conversely, if the temperature rises too rapidly, the volatile matter will explode and the crystal structure will be destroyed. Therefore, it is usually desirable to set the temperature rise rate to about 30 to 600 ° C / hour, more preferably about 60 to 300 ° C / hour. After reaching the target firing temperature, it is preferable to maintain the temperature for a certain period of time. This holding time is, for example, about 10 minutes to 2 hours.

In the present invention, it is necessary to adjust the particle size before oxidizing the carbon material. The particle size is adjusted so that the average particle size is within the range of 0.5 to 15 μm, preferably 1 to 12 μm, and more preferably 1 to 8 μm. If the particle size of the carbon material is less than 0.5 μm, it is not preferable because the particle size is increased due to fusion of the particles, and if the particle size exceeds 15 μm, it is larger than the particle size of the target activated carbon, which is not preferable. .. The method for adjusting the particle size of the carbon material is not particularly limited, and usually, a method of pulverizing by a pulverizing means such as a jet mill can be mentioned.

Next, the particle size-adjusted carbon material is oxidized. The wettability between the carbon material and the alkali activator can be improved by the oxidation treatment. The oxidation treatment needs to be carried out so that the oxygen content in the carbon material after the treatment is 3% by mass or more, preferably 4% by mass or more. If the oxygen content in the carbon material after the treatment is less than 3% by mass, the wettability with the alkali activator is not sufficiently improved and the activating effect is not exhibited, which is not preferable. Further, it is not preferable that the oxygen content in the carbon material is too large, and the upper limit of the oxygen content in the carbon material is preferably 20% by mass or less, more preferably 15% by mass or less. If it exceeds 20% by mass, the decrease in carbon yield becomes large, but the effect of improving wettability is not so large. The oxidation treatment is usually carried out by heating the carbon material in the presence of an oxidizing gas or immersing the carbon material in an aqueous acid solution.

When the carbon material is heated in the presence of an oxidizing gas, examples of the oxidizing gas include air, oxygen, ozone, nitrogen monoxide, water vapor, chlorine, etc. However, air and oxygen are preferably used, and air is used. Especially preferably used. The oxidation conditions by the oxidizing gas during the oxidation treatment differ depending on the oxidizing power of the oxidizing gas and can be appropriately determined depending on the degree of oxidation after the oxidation treatment, but the oxygen content after the oxidation treatment should satisfy the above range. It is necessary to do it. Specifically, the oxidation treatment temperature when air is used as the oxidizing gas is preferably 220 to 500 ° C, more preferably 250 to 450 ° C. If the oxidation treatment temperature is less than 220 ° C, the oxidation reaction becomes insufficient, and if it exceeds 500 ° C, the oxidation reaction proceeds too much, which is not preferable. The oxidation treatment time is not particularly limited, but it is preferably held for about 10 minutes to 2 hours after reaching the target temperature.

When a carbon material is immersed in an aqueous acid solution for oxidation treatment, the acid used for the acid treatment includes nitric acid, sulfuric acid, acetic acid and the like, and other oxidizing agents include hydrogen peroxide solution and the like. Can be mentioned. The acid treatment conditions differ depending on the oxidizing power of the acid used. For example, when nitric acid is used, the oxidation treatment temperature is usually 0 to 100 ° C, preferably 0 to 100 ° C. in a 10 to 70% aqueous solution, preferably 20 to 60% aqueous solution. Is treated at 20-80 ° C for 1-120 minutes, preferably 10-60 minutes.

Next, the oxidized carbon material is treated by a mixing step of mixing with an alkali activator and an activation step of performing an activation reaction. Of course, the method of mixing the carbon material and the alkali activator can be applied to the method of mechanically mixing the carbon material and the alkali activator, such as a conventional ball mill or a Henschel mixer, or the method of mixing the alkali activator in a molten state. In the present invention, by improving the wettability of the carbon material, it is possible to mix the alkaline activator aqueous solution and the carbon material in a wet manner, and by adopting this mixing method, activation is performed with a smaller amount of the alkali activator. It becomes possible. That is, the present invention is characterized in that the desired activated carbon can be obtained even if the amount of the alkali activator used is smaller than usual. That is, the mixing ratio of the carbon material and the activator is preferably in the range of 1: 1 to 1: 4 and more preferably in the range of 1: 1 to 1: 3 in the mass ratio (carbon material: activator) of both. The range of 1: 1.2 to 1: 2.5 is more preferred.

Examples of the alkaline activator used in the activation reaction include KOH, NaOH, RbOH, and CsOH. Of these, KOH is preferable from the viewpoint of activating effect. The reaction conditions of the activation treatment are not particularly limited as long as this reaction can be sufficiently advanced, and the reaction conditions can be the same as those of the known activation treatment performed in the production of ordinary activated carbon. For example, the alkali activator is mixed with the carbon material after the oxidation treatment and heated under high temperature conditions of preferably 400 ° C. or higher, more preferably 600 ° C. or higher, still more preferably 700 ° C. or higher. It can be carried out. The upper limit of this heating temperature is not particularly limited as long as the activation reaction proceeds without hindrance, but is preferably 900 ° C. or lower.

The activator obtained by the activation reaction is then washed. As a method for cleaning the activator, a method in which the activator is washed with a cleaning liquid and solid-liquid separated is preferably adopted. For example, a method of immersing the activator in a cleaning liquid, stirring and heating as necessary, mixing with the cleaning liquid, and then removing the cleaning liquid can be mentioned. As the cleaning liquid, it is preferable to use water and an acid aqueous solution, and for example, cleaning with water, cleaning with an acid aqueous solution, washing with water, and the like can be appropriately combined and used. As the acid aqueous solution, preferred examples include hydrohalic acid such as hydrochloric acid, hydroiodic acid and hydrobromic acid, and inorganic acids such as sulfuric acid and carbonic acid. The concentration of the acid aqueous solution can be, for example, 0.01 to 3N. Cleaning with these cleaning solutions can be repeated a plurality of times as needed.

The amount of alkali metal remaining in the washed product is not particularly limited as long as it is lower than the level that may adversely affect the electric double layer capacitor (preferably 1000 mass ppm or less), but it is usually not limited. For example, it is desirable to wash the washing wastewater so that the pH is about 7 to 8, and to remove alkali metals as much as possible. After washing, the desired activated carbon can be obtained through a drying step that is usually performed.

The activated carbon obtained by the present invention usually has an average particle size of 0.5 to 12 μm and a specific surface area of 1500 to 3000 m.²/ G, the pore volume of activated carbon after activation treatment with a pore diameter of 0.1 to 50 nm by the nitrogen gas adsorption method is 0.5 to 3 ml / g, and the pore volume by the mercury intrusion method is 0.05 to 300 μm. It is 0.4 to 5 ml / g, and the amount of residual alkali metal is 200 mass ppm or less. By using the activated carbon of the present invention having the above characteristics as an electrode of an electric double layer capacitor, it is possible to provide an electric double layer capacitor having a large capacitance per unit volume.

Next, the electric double layer capacitor of the present invention will be described. The electric double layer capacitor of the present invention is characterized by including an electrode containing activated carbon prepared as described above. The electrode may be, for example, an electrode formed by adding activated carbon and a binder, more preferably a conductive agent, and further integrated with a current collector. As the binder used here, known ones can be used, for example, fluoride such as polyolefins such as polyethylene and polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, fluoroolefin / vinyl ether copolymer crosslinked polymers and the like. Examples thereof include copolymers, celluloses such as carboxymethyl cellulose, vinyl-based polymers such as polyvinylpyrrolidone and polyvinyl alcohol, and polyacrylic acid. The content of the binder in the electrode is not particularly limited, but is appropriately selected within the range of about 0.1 to 30% by mass with respect to the total amount of activated carbon and the binder.

As the conductive agent, powders such as carbon black, powdered graphite, titanium oxide, and ruthenium oxide are used. The blending amount of the conductive agent in the electrode is appropriately selected according to the blending purpose, but is usually 1 to 50% by mass, preferably 2 to 30% by mass, based on the total amount of activated carbon, binder and conductive agent. It is appropriately selected within the range of degree. As a method for mixing the activated carbon, the binder, and the conductive agent, a known method is appropriately applied. For example, a solvent having a property of dissolving the binder is added to the above components to form a slurry. A method of uniformly coating on an electric body or a method of kneading the above components without adding a solvent and then pressure molding at room temperature or heating is adopted. Further, as the current collector, a known material and shape can be used, and for example, a metal such as aluminum, titanium, tantalum and nickel, or an alloy such as stainless steel can be used.

The unit cell of the electric double layer capacitor of the present invention generally uses a pair of the above electrodes as a positive electrode and a negative electrode, faces each other via a separator (polypropylene fiber non-woven fabric, glass fiber non-woven fabric, synthetic cellulose paper, etc.), and is immersed in an electrolytic solution. Formed by As the electrolytic solution, a known aqueous electrolytic solution or organic electrolytic solution can be used, but it is more preferable to use an organic electrolytic solution. As such an organic electrolytic solution, those used as a solvent for an electrolytic solution for electrochemistry can be used. For example, propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyrolactone, sulforane, sulfolan derivative, 3 -Methyl sulfolane, 1,2-dimethoxyethane, acetonitrile, glutaronitrile, valeronitrile, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, dimethoxyethane, methylformate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate and the like can be mentioned. .. In addition, you may mix and use these electrolytic solutions.

The supporting electrolyte in the organic electrolytic solution is not particularly limited, but various salts, acids, alkalis and the like usually used in the field of electrochemistry or the field of batteries can be used, for example, alkali metal salts. Inorganic ion salts such as alkaline earth metal salts, quaternary ammonium salts, cyclic quaternary ammonium salts, quaternary phosphonium salts, etc. can be mentioned (C).₂H₅)₄NBF₄, (C₂H₅)₃(CH₃) NBF₄, (C₂H₅)₄PBF₄, (C₂H₅)₃(CH₃) PBF₄Etc. are preferred. The concentration of these salts in the electrolytic solution is usually appropriately selected within the range of about 0.1 to 5 mol / l, preferably about 0.5 to 3 mol / l. The more specific configuration of the electric double layer capacitor is not particularly limited, but for example, it is housed in a metal case via a separator between a pair of thin sheet-shaped or disk-shaped electrodes (positive electrode and negative electrode) having a thickness of 10 to 500 μm. Examples include a coin type, a winding type in which a pair of electrodes are wound via a separator, and a laminated type in which a large number of electrode groups are stacked via a separator.

<p> Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. The various analysis methods are as follows. Oxygen mass%: Carbon mass%, hydrogen mass%, and nitrogen mass% of the sample were determined using an elemental analyzer (NCH-22F type manufactured by Sumika Analytical Center Co., Ltd.), and the rest was defined as oxygen mass%. Volatile content: Measured according to the method described in JIS M 8812 "Coals and cokes-Industrial analysis method". Specific surface area / pore volume: Calculated by the BET method from the adsorption isotherm obtained from nitrogen gas adsorption using an automatic specific surface area measuring device (BELSORP-miniII type manufactured by Nippon Bell Co., Ltd.). Particle size distribution measurement: Using a laser diffraction type particle size distribution measuring device (LA-950 type manufactured by HORIBA, Ltd.), a small amount of surfactant was added using water as a dispersion medium, and the measurement was performed after irradiation with ultrasonic waves. The 50% particle size (average particle size) was determined from the obtained volume-based particle size integral curve.</p><p>(Example 1) Raw petroleum coke with an average particle size of 2 mm or less was pulverized with a jet mill so that the average particle size was 8 μm. The pulverized product was heated in an air atmosphere at a heating rate of 200 ° C./hour and held at 250 ° C. for 1 hour for oxidation treatment. To 100 parts by mass of this oxidized product, 200 parts by mass of potassium hydroxide was added and mixed with a ball mill, and further treated in a nitrogen gas atmosphere at 750 ° C. for 1 hour to carry out an activation reaction. After the reaction, water washing and acid washing (using hydrochloric acid) were repeated to remove the metallic potassium remaining in the carbon material and dried to obtain an activator (activated carbon for an electric double layer capacitor electrode). The specific surface area of the obtained activator, that is, the activated carbon for electrodes (carbon material for electrodes) by the nitrogen gas adsorption method (BET method) is 2380 m.²/ g, pore volume is 1.129 cm³It was / g. Using the obtained carbon material for electrodes, carbon black and granular polytetrafluoroethylene (PTFE) were mixed and pressed to prepare a carbon electrode sheet having a thickness of about 150 μm to 200 μm. An electrode was cut out from this sheet to a predetermined size, and a laminate cell shown in FIG. 1 was produced to evaluate a carbon electrode material as a capacitor. The electrolyte is 1.5M triethylmethylammonium tetrafluoroborate (TEMA / BF).₄) Propylene carbonate (PC) solution was used. Next, the initial characteristics (capacitance, internal resistance) of the capacitor were measured using the laminated cell. The measurement method is shown in Fig. 2. For the capacitance, the total amount of energy stored in the capacitor was measured, and the capacitance was calculated from that value (energy conversion method). The internal resistance was calculated from the IR drop immediately after the start of discharge. Furthermore, as the rate characteristic of the capacitor, the constant current discharge value is 0.36mA / cm.²~ 72mA / cm²The capacitance when changed to was measured. The result of the rate characteristic is 0.36mA / cm²Based on the capacitance at the time of discharge, it was calculated as the retention rate of the capacitance at each constant current discharge. The results are shown in Tables 1 and 2. The activation conditions and results of Examples 2 to 6 and Comparative Examples 1 to 5 are summarized in Tables 1 and 2.</p><p>(Example 2) 140 parts by mass of potassium hydroxide was dissolved in water and mixed with 100 parts by mass of the oxidized product obtained under the same conditions except that the oxidation treatment temperature in Example 1 was 450 ° C. Activated carbon for electrodes was produced by the same operation as in Example 1 except that the mixture obtained by drying in 1 for 5 hours was subjected to an activation reaction. The specific surface area of the obtained activator (carbon material for electrodes) by the nitrogen gas adsorption method (BET method) is 1694 m.²/ g, pore volume is 0.790 cm³It was / g.</p><p>(Example 3) Activated carbon for electrodes was produced by the same operation as in Example 1 except that 160 parts by mass of potassium hydroxide was mixed with 100 parts by mass of the same oxidized product obtained in Example 1 by a ball mill. The specific surface area of the obtained activator (carbon material for electrodes) by the nitrogen gas adsorption method (BET method) is 1608 m.²/ g, pore volume is 0.757 cm³It was / g.</p><p>(Example 4) The same milled raw coke used in Example 1 was treated in 10% nitric acid at 60 ° C. for 1 hour. After allowing to cool, the processed product was filtered, washed until the furnace liquid became pH 4 or higher, and dried at 110 ° C. for 5 hours. Table 1 shows the physical characteristics of the processed material. This treated product was mixed with potassium hydroxide, activated, washed and dried in the same manner as in Example 1 to obtain activated carbon. Specific surface area is 2512m²/ g, pore volume is 1.202 cm³It was / g.</p><p>(Example 5) The same raw coke used in Example 1 was calcined in a nitrogen gas atmosphere at 550 ° C for 1 hour. The temperature rising rate at that time was 200 ° C / hour. This fired product was pulverized with a jet mill so that the average particle size was 7 μm, and the pulverized product was oxidized at 450 ° C. for 1 hour in the same manner as in Example 3. Table 1 shows the elemental analysis values of the treated product. Further, the treated product was mixed with potassium hydroxide in the same manner as in Example 1, activated at 700 ° C. for 1 hour, washed and dried to obtain activated carbon. Specific surface area is 2755m²/ g, pore volume is 1.323 cm³It was / g.</p><p>(Example 6) The same oxidized product used in Example 5 was mixed with sodium hydroxide in the same manner as in Example 1, activated at 750 ° C. for 1 hour, washed and dried to obtain activated carbon. Specific surface area is 1704m²/ g, pore volume is 0.926 cm³It was / g.</p><p>(Comparative example 1) The same raw material raw coke used in Example 1 was pulverized by a jet mill (average particle size 8 μm) and activated, washed and dried in the same manner as in Example 1 without oxidation treatment to obtain activated carbon. This specific surface area is 2013m²It was / g.</p><p>(Comparative example 2) The same raw material raw coke used in Example 1 was pulverized by a jet mill (average particle size 8 μm) and activated, washed and dried in the same manner as in Example 2 without oxidation treatment to obtain activated carbon. The specific surface area of the obtained activator (carbon material for electrodes) by the nitrogen gas adsorption method (BET method) is 768 m.²/ g, pore volume is 0.363 cm³It was / g.</p><p>(Comparative example 3) Oxidation treatment was performed in the same manner as in Example 3, and activated carbon for electrodes was prepared in the same manner as in Example 3 except that 70 parts by mass of potassium hydroxide was dissolved in water and mixed with 100 parts by mass of the oxidized product. Manufactured. The specific surface area of the obtained activator (carbon material for electrodes) by the nitrogen gas adsorption method (BET method) is 569 m.²/ g, pore volume 0.267 cm³It was / g.</p><p>(Comparative example 4) The same raw material raw coke used in Example 1 was crushed with a jet mill (average particle size 8 μm), heated at a heating rate of 200 ° C / hour in an air atmosphere, and held at 200 ° C for 1 hour. Was processed. This treated product was activated, washed and dried in the same manner as in Example 1 to obtain activated carbon. This specific surface area is 2062m²It was / g.</p><p>(Comparative example 5) The same pulverized product obtained by adjusting the particle size in Example 5 was heated in an air atmosphere at a heating rate of 200 ° C./hour and held at 200 ° C. for 1 hour for treatment. This treated product was activated, washed and dried in the same manner as in Example 5 to obtain activated carbon. This specific surface area is 1756m²It was / g.</p><p><tables num="1"><img file="JP2011136856A_D0001.tif" /></tables><tables num="2"><img file="JP2011136856A_D0002.tif" /></tables></p>

According to the method of the present invention, the reaction with the carbon material can proceed extremely efficiently with a smaller amount of the alkali activator than before, so that the cost is low, the uniformity is excellent, and the capacitance per unit volume is excellent. It is possible to obtain a large amount of activated carbon, and its industrial value is extremely large.