Polypyrrole and poly(3-methyl thiophene)-based solid state redox supercapacitors using ion conducting polymer electrolyte

Polypyrrole (pPy) and poly(3-methyl thiophene) (pMeT)-based Type I and Type II solid state redox supercapacitors have been constructed using polymeric electrolytes, polvvinyl alcohol (P%,A)-H3PO4 blend and polyethylene oxide (PEO)-NaClO4 complex plasticised with polyethylene glycol (PEG) and gel electrolyte, polymethyl methacrylate (PMMA)-ethylene carbonate (EC)-propylene carbonate (PC)-NaClO4. The performance characteristics of the capacitor cells have been evaluated using galvanostatic charge-discharge method. The polypyrrole-based symmetrical Type I capacitor cells show almost symmetrical charge-discharge characteristics with the discharge capacitance of 8.0-15.0 mF cm(-2). The same order of specific capacitance has been observed for pMeT-based Type I capacitors but their working voltage range is limited between 0.5 and 1.0 V The asymmetrical Type II capacitor cells show the polarity-dependent behaviour in which the working voltage limit and capacitance values depend upon the polarity of the applied charging current. (C) 2002 Elsevier Science B.V All rights reserved.