Abstract: In an electric double-layer capacitor, a solution of a quaternary ammonium borofluoride compound in propylene carbonate is used as an electrolyte. The electrode includes alkali-activated carbon made using meso-phase pitch as a starting material, and a conductive filler having a rest potential smaller than that of the alkali-activated carbon in the electrolyte. The amount Fc of conductive filler incorporated in the electrode is set in a range of 10% by weight≦Fc≦40% by weight. Such electric double-layer capacitor has a large electrostatic capacity and excellent durability.

Abstract: A method for preparing the electrolytic solution of an electric double-layer capacitor is provided, which undergoes cyclical charging and discharging within a predetermined operating range of voltage. The capacitor includes the electrolytic solution, electrodes and a casing for housing the electrolytic solution and electrodes. The method includes the step of preparing an ion concentration of the electrolytic solution so that the electrolytic solution turns to a nonconductor at a first predetermined voltage, which is so set as to be equal to or greater than the upper limit of the predetermined operating range of voltage and less than or equal to the maximum allowable voltage of the capacitor.

Abstract: An alkali-activated carbon for an electric double layer capacitor electrode is provided in which the alkali-activated carbon has a first pore group having a pore diameter D in the range of D≦2 nm, a second pore group having a pore diameter D in the range of 2 nm<D≦10 nm, and a third pore group having a pore diameter D in the range of 10 nm<D≦300 nm. When the pore volume of the first pore group is Pv1, the pore volume of the second pore group is Pv2, the pore volume of the third pore group is Pv3, and the sum total Pv0 of the pore volumes is Pv0=Pv1+Pv2+Pv3, the pore volumes being obtained by a nitrogen gas adsorption method, the proportion A of the pore volume Pv1 of the first pore group relative to the sum total Pv0 of the pore volumes is A≧60%, and the proportion B of the pore volume Pv2 of the second pore group relative to the sum total Pv0 of the pore volumes is B≧8%.

Abstract: Activated carbon for an electrode of an electric double-layer capacitor is produced by subjecting a carbon material sequentially to a carbonizing treatment and an alkali activating treatment, and by using a carbon material. The carbon material used is a condensed polycyclic aromatic compound (CPAC) which has a condensed ring (CR) and at least one aliphatic hydrocarbon radical (R) bonded to said condensed ring (CR). The condensed ring (CR) includes at least one alicyclic hydrocarbon structure moiety (ALC). In an analysis chart resulting from a 13C-NMR spectroscopy of the condensed polycyclic aromatic compound, a signal intensity ratio IL/IR is equal to or larger than 0.2, and a signal intensity ratio IC/IR is equal to or larger than 0.14, wherein IR represents a signal intensity of an aromatic peak; IL represents a signal intensity of an aliphatic hydrocarbon peak; and IC represents a signal intensity of an alicyclic hydrocarbon peak.

Abstract: A cylindrical electric double-layer capacitor includes a cylindrical sealed vessel housing an electrode roll and an electrolyte solution. The electrode roll is formed of a rolled superposed assembly having band-shaped positive and negative poles and two band-shaped separators sandwiching one of the band-shaped positive and negative poles. Each of the band-shaped positive and negative poles includes a band-shaped collector and a pair of polarizing electrodes formed in a laminated manner on opposite surfaces of the band-shaped collector. In a state in which the electrode roll has been accommodated in the sealed vessel along with the electrolyte solution, an outer diameter D1 of the electrode roll and an inner diameter D2 of the sealed vessel are brought into a relationship of D1=D2 by at least one of swelling of the polarizing electrodes caused by the electrolyte solution and expansion of the polarizing electrodes caused by an electrical charge.

Abstract: A method for preparing the electrolytic solution of an electric double-layer capacitor is provided, which undergoes cyclical charging and discharging within a predetermined operating range of voltage. The capacitor includes the electrolytic solution, electrodes and a casing for housing the electrolytic solution and electrodes. The method includes the step of preparing an ion concentration of the electrolytic solution so that the electrolytic solution turns to a nonconductor at a first predetermined voltage, which is so set as to be equal to or greater than the upper limit of the predetermined operating range of voltage and less than or equal to the maximum allowable voltage of the capacitor.

Abstract: Activated carbon for an electrode of an electric double-layer capacitor is produced by subjecting a carbon material sequentially to a carbonizing treatment and an alkali activating treatment, and by using a carbon material. The carbon material used is a condensed polycyclic aromatic compound (CPAC) which has a condensed ring (CR) and at least one aliphatic hydrocarbon radical (R) bonded to said condensed ring (CR). The condensed ring (CR) includes at least one alicyclic hydrocarbon structure moiety (ALC). In an analysis chart resulting from a 13C-NMR spectroscopy of the condensed polycyclic aromatic compound, a signal intensity ratio IL/IR is equal to or larger than 0.2, and a signal intensity ratio IC/IR is equal to or larger than 0.14, wherein IR represents a signal intensity of an aromatic peak; IL represents a signal intensity of an aliphatic hydrocarbon peak; and IC represents a signal intensity of an alicyclic hydrocarbon peak.

Abstract: A cylindrical electric double-layer capacitor includes a cylindrical sealed vessel housing an electrode roll and an electrolyte solution. The electrode roll is formed of a rolled superposed assembly comprising band-shaped positive and negative poles and two band-shaped separators sandwiching one of the band-shaped positive and negative poles. Each of the band-shaped positive and negative poles includes a band-shaped collector and a pair of polarizing electrodes formed in a laminated manner on opposite surfaces of the band-shaped collector. In a state in which the electrode roll has been accommodated in the sealed vessel along with the electrolyte solution, an outer diameter D1 of the electrode roll and an inner diameter D2 of the sealed vessel are brought into a relationship of D1=D2 by at least one of swelling of the polarizing electrodes caused by the electrolyte solution and expansion of the polarizing electrodes caused by an electrical charge.

Abstract: A carbonized product 10 used for production of activated carbon for an electrode of an electric double-layer capacitor, includes a plurality of crystallites 12 each having a graphite structure in an amorphous carbon matrix 11. The interlayer distance d002 of the crystallites 12 is set a value equal to or larger than 0.347 nm. Thus, by using this carbonized product, it is possible to produce activated carbon having a high electrostatic capacity density (F/cc) for an electrode of an electric double-layer capacitor.

Abstract: There is disclosed an electric double-layer capacitor that is adapted for use in an electric vehicle, for example, and uses aluminum collector electrodes. A native oxide film is formed on each aluminum electrode. Hard granular carbon is made to penetrate through the oxide film into each aluminum electrode. The aluminum electrodes are connected with positive and negative polarizing electrodes, respectively, via the granular carbon, thus lowering the contact resistance.

Abstract: A cylindrical electric double-layer capacitor 1 includes an electrode roll made by spirally rolling a superposed assembly formed of a band-shaped positive pole and a band-shaped negative pole superposed on each other with a first separator interposed therebetween and a second separator superposed on one of the band-shaped positive and negative poles so that the second separator is located on an outermost side, and a vessel in which the electrode roll is accommodated. A cylindrical electrode is mounted on the electrode roll to come into contact with an outer peripheral surface of the electrode roll. The polarity of the cylindrical electrode is set to be opposite from that of a portion of one of the band-shaped positive and negative poles which is located on an outermost periphery of the electrode roll.

Abstract: A cylindrical electric double-layer capacitor 1 includes an electrode roll made by spirally rolling a superposed assembly formed of a band-shaped positive pole and a band-shaped negative pole superposed on each other with a first separator interposed therebetween and a second separator superposed on one of the band-shaped positive and negative poles so that the second separator is located on an outermost side, and a vessel in which the electrode roll is accommodated. A cylindrical electrode is mounted on the electrode roll to come into contact with an outer peripheral surface of the electrode roll. The polarity of the cylindrical electrode is set to be opposite from that of a portion of one of the band-shaped positive and negative poles which is located on an outermost periphery of the electrode roll.

Abstract: A cylindrical electric double-layer capacitor includes an electrode winding which is formed by superposing band-shaped positive and negative electrodes one on another with a first separator interposed therebetween, superposing a second separator onto one of the band-shaped positive and negative electrodes to provide a superposed material, and by spirally winding the superposed material such that the second separator is located on an outermost side, and a container having the electrode winding accommodated therein. A cylindrical electrode is provided on an inner peripheral surface of the container opposed to an outer peripheral surface of the electrode winding. The polarity of the cylindrical electrode is set at a polarity opposite from the polarity of that portion of the band-shaped negative electrode, which is located on an outermost periphery of the electrode winding.

Abstract: An electrochemical capacitor is provided having double-layer electrode elements interposed with a separator. The electrode elements being made of activated carbon and impregnated with a nonaqueous electrolytic liquid yields a capacitor with low internal resistance, greater capacitance and higher energy density. Methods for producing the activated carbon electrodes and the capacitor assembly are also described.

Abstract: An activated carbon for an electrode of an electric double-layer capacitor includes a plurality of crystallites having a graphite structure in an amorphous carbon, in which the interlaminar distance d002 of the plurality of crystallites is in a range of 0.388≦d002≦0.420 nm.

Abstract: An activated carbon for electric double layer capacitor whose rate of FS (filling swing) in an &agr;s-plot by the nitrogen adsorption method is at most 27 cm3/g STP. An activated carbon electrode formed with the activated carbon. An electric double layer capacitor equipped with the activated carbon electrodes as polarizable electrodes and having excellent durability.

Abstract: An activated carbon for an electrode of an electric double-layer capacitor includes an activated carbon fiber produced by using a graphitizing carbon, and an activated carbon powder obtained by pulverizing the activated carbon fiber, thereby increasing the density of the electrode.

Abstract: Activated carbon for electric double-layer capacitor has a high electrostatic capacity density. An area rate of edge faces in a surface (including inner surfaces of fine bores) of the activated carbon for an electric double-layer capacitor is equal to or higher than 20%.

Abstract: An electrochemical capacitor has a pair of positive and negative electrode elements each having a solid electrode disposed on a surface of a current collector. The positive and negative electrode elements are disposed in confronting relation to each other with a separator interposed therebetween. The positive and negative electrode elements, together with an electrolytic solution, are housed in the casing. The solid electrode of the negative electrode element is made of a lithium vanadium oxide and an electrically conductive filler, and the solid electrode of the positive electrode element is made of activated carbon.

Abstract: Activated carbon for use in an electric double layer capacitor is in the form of particles produced by crushing activated carbon or fibers of activated carbon. The particles have a surface covered at least partly with a laminated structure layer of graphite formed along the surface.