Patent ID: 7911767

Claim:
An electric double-layer capacitor comprising: an electrode portion composed of an anode and a cathode; a separator for providing electrical isolation between the anode and cathode; and an electrolyte solution which is filled in a space between the anode and cathode so as to form electric double-layers on surfaces of the anode and cathode when a predetermined voltage is applied, and in which a mixed solute of butylmethylpyrrolidinium of 0.25M to 1.5M and tetraethylammonium tetrafluoroborate of 1M to 0.25M is mixed in a solvent so as to have a concentration of 1.25 to 2.0 mol/L, wherein the solvent is propylene caronate (PC) or a mixture of the propylene carbonate (PC) and ethylene carbonate (EC).