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, polyvinyl alcohol (PVA)–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.