Patent ID: 7897281

Claim:
An electric double layer capacitor having an electrolyte and an electrode containing an electrode layer bound onto a current collector; wherein the electrode layer comprises a carbonaceous material and a binder polymer which comprises: 50 to 98% by mole of monomer units (a) derived from a compound represented by the following formula: CH 2 ═CR 1 —COOR 2 (1) wherein R 1 represents a hydrogen atom or an alkyl group, and R 2 represents an alkyl group having 2 to 18 carbon atoms or a cycloalkyl group having 3 to 18 carbon atoms, 1 to 30% by mole of monomer units (b) derived from acrylonitrile, and 0.1 to 10% by mole of monomer units (c) derived from a multifunctional ethylenically unsaturated carboxylic acid ester; and has a glass transition temperature from −80 to 0° C., wherein the electrolyte includes tetraethylammonium tetrafluoroborate, triethylmonomethylammonium tetrafluoroborate, or tetraethylammonium hexafluorophosphate.