Conducting Polymer with Metal Oxide for Electrochemical Capacitor: Poly(3,4-ethylenedioxythiophene) RuO[sub x] Electrode

Abstract

Electrodes made by depositing ruthenium oxide on conducting poly(3,4-ethylenedioxythiophene) (PEDT) were studied for their electrochemical and impedance properties. In acidic electrolytes the PEDT­RuOxPEDT­RuOx composite electrodes exhibited large capacitance due to contributions from the double-layer capacitance and the faradaic capacitance. Optimization of the thickness of the conducting polymer film and the amount of ruthenium deposition was found necessary to realize large specific capacitance. The specific capacitance based on the combined mass of PEDT­RuOxPEDT­RuOx was 420 F/g, and the specific capacitance based on the mass of RuO2RuO2 was 930 F/g. The energy storage density of a capacitance cell constructed with a pair of PEDT­RuOxPEDT­RuOx electrodes reached 27.5 Wh/kg when the cell was charged to 1.0 V. The impedance analysis of the composite electrode revealed that both the double-layer capacitance and the pseudocapacitance originating from both PEDT and RuOxRuOx contribute to large specific capacitance. © 2001 The Electrochemical Society. All rights reserved.