Graphitic nanofibers, which include tubular fullerenes (commonly called 'buckytubes'), nanotubes and fibrils, which are fucntionalized by chemical substitution, are used as electrodes in electrochemical capacitors. The graphitic nanofiber based electrode increases the performance of the electrochemical capacitors.

Graphitic nanofibers in electrochemical capacitors

A method of making an electrode structure, the electrode structure and a double layer capacitor including the electrode structure, the method comprising the steps of: forming a plurality of electrodes, each having a current collector plate, a primary coating formed on each side of the collector plate, the primary coating including conducting carbon powder and a binder, and a secondary coating formed on each primary coating, the secondary coating including activated carbon powder, a solvent and a binder; positioning a respective separator between each electrodes while stacking the electrodes such that the respective separator is juxtaposed against respective secondary coatings of adjacent electrodes that electrically insulates the adjacent electrodes, whereby forming an electrode stack; and rolling the electrode stack into a cylindrical electrode structure.

Electrochemical double layer capacitor having carbon powder electrodes

Activated carbon adapted for electric double layer capacitors is provided, which capacitors can give a large power density per unit volume and which capacitors, even when charge-and-discharge cycle is repeated under a large current or a constant voltage is continuously applied for a long time, undergo less decrease in output density. That is, the present invention relates to the activated carbon manufactured by carbonization of coconut shell, which has a BET specific surface area of 2000 m2/g to 2500 m2/g, an average pore diameter of 1.95 nm (19.5 Å) to 2.20 nm (22 Å) and a pore volume of pores having a pore diameter calculated according to a Cranston-Inkley method of 5.0 nm (50 Å) to 30.0 nm (300 Å), of 0.05 cm3/g to 0.15 cm3/g.

Activated carbon for use in electric double layer capacitors

The present application is directed to mesoporous carbon materials comprising bi-functional catalysts. The mesoporous carbon materials find utility in any number of electrical devices, for example, in lithium-air batteries. Methods for making the disclosed carbon materials, and devices comprising the same, are also disclosed.

Mesoporous carbon materials comprising bifunctional catalysts

An electrode material suitable for high capacitance and large-current discharge and used for electric double layer capacitors and cells is characterized in that a very sharp pore size distribution is displayed in a mesopore region, and the volume of pores having pore sizes of X ± α nm (3.0≤X∫10, α = 1.0: the distribution range of pore size) accounts for more than 15 % of the total volume of mesopores having pore sizes ranging from 2.0 to 50 nm. The electrode material is produced by adding at least one kind of a transition metal and its compound to a carbonaceous material or a carbon precursor and heating the mixture to 600 °C or more.

Electrode material and method for producing the same

An activated carbon has a specific surface area of pores with a pore diameter of not less than 20 Å in the pore distribution determined from the nitrogen adsorption isotherm of not less than 1,000 m2 /g, and the ratio of the specific surface area of the pores with a pore diameter of not less than 20 Å to the specific surface area of the whole pores of not less than 0.45.

Activated carbon, process for the preparation thereof and electric double layer-type capacitor electrode

PROBLEM TO BE SOLVED: To provide activated charcoal which has a high output density per unit volume that has small drop, even when charging and discharging are repeated under a large current or a constant voltage is continuously impressed upon the carbon for a long time and is suitable for electric double-layer capacitors. SOLUTION: This activated charcoal is obtained by carbonizing coconut husks and has a BET specific surface area of 2,000-2,500 m2/g and a mean pore diameter of 1.95-2.20 nm (19.5-22.0 Å). In addition, the pore volumes of the pores, having diameters of 50-300 Åcalculated by the Cranston-Inclay method are 0.05-0.15 cm3/g.

Activated charcoal for electric double-layer capacitor

PURPOSE: To increase the specific surface of mesopore region necessary to a large-capacity capacitor, to decrease the specific surface of a micropore region and to efficiently utilize the specific surface by specifying the pore distribution obtained from a nitrogen adsorption isotherm. CONSTITUTION: At least one kind of carbonaceous material among coal, coconut shell, sawdust, resin, etc., is carbonized at >=300 deg.C to obtain a granular, granulated or powdery carbonaceous material. The carbonaceous material is activated with steam at >=900 deg.C to obtain the material with the specific surface of >=20Å pore diameter controlled to >=1000m /g and its ratio to the total specific surface to >=0.30. The activated material is further activated at 400-1000 deg.C with an alkali metal hydroxide such as KOH and NaOH and an alkaline-earth metal hydroxide as the activator to obtain the activated carbon. When the activated carbon is formed into a capacitor, etc., a binder such as polytetraethylene resin is added by one to several % and mixed, and the mixture is press-formed. When an electrode is formed, a conductive material such as conductive carbon black is added to decrease the resistance of the electrode.

Activated carbon, its production and electrode for electric-double-layer capacitor

PROBLEM TO BE SOLVED: To provide an electric double-layer capacitor exhibiting good low- temperature properties and a carbon material used for its electrodes. SOLUTION: An electric double layer capacitor is formed by using a nonaqueous electrolytic solution and polarized electrodes, containing mainly a carbon material for the two poles. In this case, the carbon material is formed by treating a carbon raw material in alkaline. The inter-face distance d002 measured by X-ray diffraction is 0.365 nm or less, and the ratio of surface area to BET measured by nitrogen adsorption method is 0.5 m /g-290 m /g.

Yoshitaka Takeda

Papers

Activated carbon for use in electric double layer capacitors

Activated carbon, process for the preparation thereof and electric double layer-type capacitor electrode

Activated charcoal for electric double-layer capacitor

Activated carbon, its production and electrode for electric-double-layer capacitor

Electric double-layer capacitor and carbon material used for the capacitor