US Patent 7924548 Electric double layer capacitor

An electric double layer capacitor includes a positive electrode, a negative electrode which faces the positive electrode and is isolated therefrom, and an electrolyte solution. The positive electrode includes a first current collector of a metal foil and a first polarizable electrode layer on the first current collector, the first polarizable electrode layer containing a phosphorus compound. The negative electrode includes a second current collector of a metal foil and a second polarizable electrode layer on the second current collector. The electrolyte solution, with which the first and second polarizable electrode layers are impregnated, has fluorine-containing anions as an electrolyte solute.