Conductivity and capacitance properties of a supercapacitor based on Nafion electrolyte in a nonaqueous system

The fabrication and evaluation of solid-state supercapacitors based on a Nafion electrolyte in aqueous and nonaqueous systems are described. The Nafion membrane in a nonaqueous system is impregnated with 30% of phosphoric acid in ethylene glycol and characterized in a supercapacitor configuration by cyclic voltammetry and ac impedance spectroscopy. A high proton conductivity of 2.2 x 10(-2) S cm(-1) for the Nafion-based supercapacitor in the nonaqueous system was measured at room temperature and is about half that of the aqueous system. A capacitance of 90 F/g and an energy density of 7 Wh/kg for the nonaqueous supercapacitor was obtained. A stable capacitance performance was demonstrated for 2500 cycles in a potential range from 0 to 1.5 V. (C) 2004 The Electrochemical Society.