A gel polymer electrolyte based on PVdF and ZnCl2 for an electrochemical double layer capacitor

This paper is based on fabrication and characterization of a gel polymer electrolyte and evaluation its potential candidacy for electrochemical double layer capacitors. Gel polymer electrolyte samples consist of polyvinylidenefluoride (PVdF), zinc chloride (ZnCl2), ethylene carbonate (EC) and propylene carbonate (PC) Salt and polymer concentrations were varied to obtain the best conductivity. The maximum room temperature conductivity of 8.6 × 10-4 Scm-1 was obtained with the composition, 6.875PVdF:1 ZnCl2: 12.5 EC : 12.5 PC (by weight). DC polarization test results proved that gel polymer electrolyte is predominantly an ionic conductor. The electrochemical double layer capacitor was assembled having two identical graphite electrodes with the gel polymer electrolyte. Cyclic voltammetry measurements were taken in different potential windows and at various scan rates using three electrode setups. The results proved the dependency of the potential window as well as the scan rate on the performance of the capacitor. Continuous charge discharge cycling for 50 cycles showed that the device is rather stable in spite of the decrement of specific capacity that occurred at the beginning. The initial specific capacity was about 8.68 Fg-1. The present study showcases the value of Sri Lankan natural graphite in energy applications.