Performance of an ionic liquid based gel polymer electrolyte and its application in a redox capacitor

In the modern technology based society, attraction towards the redox capacitors is increasing rapidly as one of the best energy storage devices. Capacitors fabricated by using the Ionic liquid (IL) based Gel polymer elec-trolytes (GPEs) have been attracted tremendously as eco-friendly energy sources based on their unique features such as satisfactory specific capacitance, good cycle ability, and good stability. The present study reports about a redox capacitor fabricated with the IL, 1-ethyl-3-methylimidazoliumbis(trifluoromethanesulfonyl) imide (1E3Mbis(TF)I) and sodium trifluoromethanesulfonate (CF3NaO3S-NaTF). Reported highest room tempera -ture conductivity was 7.7 x 10(-4) S cm(-1) with the composition of 1 Polyvinyl chloride (PVC):1 1E3MIbis (TF)I:2 NaTF. The conductivity mechanism of GPEs follows free volume theory. The redox capacitor with the configuration, polypyrrole (PPy):NaTF/1 PVC:1 1E3MIbis(TF)I:2 NaTF/PPy:NaTF showed a single elec-trode specific capacitance (CSC) of 31.5 F g(-1) based on Nyquist plot. Its relaxation time was 13.6 s and this confirms fairly fast charge storage process. Initial CSC of the redox capacitor was about 126.3 F g(-1) for the potential window from -1.2 V to 1.2 V. Initial single electrode discharge capacitance (Csd) observed by Galvanostatic charge discharge (GCD) test under a constant current of 240 mu A was 24.1 F g(-1). It was gradually decreased to 9.57 F g(-1) with cycling due to the formation of a passivation layer on the electrode and the degra-dation of electrolyte/electrode interface.