Effect of anionic size of PMMA Based Polymer Gel Electrolytes for Redox Capacitor

Different types of polypyrrole based electrochemical redox supercapacitors have been fabricated using the polymeric gel electrolytes comprising of polymethyl methacrylate (PMMA)propylene carbonate (PC)-ethylene carbonate (EC)-sodium salts of different anions [I , (ClO4) , (SCN) ] with a view to using them as electrolytes in redox supercapacitors to see the effect of anionic size in the performance of electrochemical capacitor cells. These gel electrolytes exhibit high ionic conductivity of the order of nearly 10 -3 S/cm at room temperature with good mechanical/dynamical stability suitable for the fabrication of capacitor cells. Comparative studies of all the above supercapacitor cells have been characterized using complex impedance spectroscopy, linear sweep cyclic voltammetry and constant current charge discharge tests. The capacitance values of the cells have been observed to be in the range of 31-75 mF cm -2 which is equivalent to single electrode specific capacitance of 207-501 F/gm. It corresponds to the energy density of 03-30 Wh/kg and power density of 0204 kW/kg. Working voltage was kept at 1 V. Further it was observed that the capacitance of the capacitor cells is highly dependent on the anionic size of the salts used in the synthesis of gel electrolytes and it was in the order of NaI based gel > NaSCN > NaClO4,showing smaller anion of the salts with higher capacitance values