| abstract |
An electric double layer capacitor utilizing an electric double layer formed by the interface of an electrolyte solution and polarizable electrodes, wherein the electrolyte solution comprises a quaternary phosphonium salt of the formula I dissolved in an organic solvent:n wherein each of R₁, R₂, R₃ and R₄ is a hydrogen atom, an alkyl group having from l to l5 carbon atoms or an aryl group having from 6 to l5 carbon atoms, provided that not all of R₁ to R₄ are hydrogen atoms, and X is BF₄, PF₆, ClO₄, AsF₆, SbF₆, AlCl₄ or R f SO₃ wherein R f is a fluoroalkyl group having from l to 8 carbon atoms. |