Effect of polymerisation current density of electrodes on the performance of polypyrrole based redox-capacitor

Abstract

Use of redox-capacitors is one of the effective and economic solutions to the demand for power sources. Redoxcapacitors replace the role of batteries and conventional capacitors by hundred times of the power density and energy density. Research activities are being continued to fabricate more comprehensive supercapacitors. Among those, fabrication of the symmetric polymer capacitor is dominant because of its simplicity. In this study, the effect of polymerisation current density on the performance of a symmetric polymer redoxcapacitor is reported. Conducting polymer, polypyrrole (PPy) was used as the electrodes, while a gel polymer electrolyte (GPE) based on polyvinylidenefluoride (PVDF) was used as the electrolyte. Fabrication of the redox-capacitors was carried out in the configuration of PPy : GPE : PPy. They were characterised using cyclic voltammetry tests, continuous galvanostatic charge-discharge tests and electrochemical impedance spectroscopy. An average specific capacitance value of 12 Fg-1 could be obtained by cyclic voltammetry measurements. It was about 7 Fg-1 as per the galvanostatic charge-discharge test. The specific capacity remains rather stable upon continuous cycling. An increase was noticed in specific capacity with the increase in polymerisation current density. From the impedance spectroscopy measurements, it was observed that with increasing polymerisation current density, the capacitive nature of the redox-capacitors can be improved.