Electrical property enhancement of poly (vinyl alcohol-co-ethylene)–based gel polymer electrolyte incorporated with triglyme for electric double-layer capacitors (EDLCs)

Liquid electrolytes (LEs) have been widely exploited in commercial electric double-layer capacitors (EDLCs). However, LEs pose problems of leakage, flammability, and volatility. In this work, gel polymer electrolytes (GPEs) have been prepared using poly (vinyl alcohol-co-ethylene) (PVA-co-PE), dimethyl sulfoxide (DMSO), sodium iodide (NaI), and triethylene glycol dimethyl ether (triglyme). After addition of triglyme, the ionic conductivity of GPEs increased about 19.84% larger than the GPEs without the presence of triglyme. This is contributed to the existence of abundant oxygen-containing functional groups provided by triglyme that formed crown ether around Na + ions. Thus, the number of unpaired ions increased in the GPEs. The prepared GPEs have been used to fabricate EDLCs. AC/G10/AC containing triglyme achieved the maximum specific capacitance of 25.95 F/g at 3 mV/s and 13.85 F/g at 0.03 A/g. In addition, AC/G10/AC retained capacitance of ~ 98% after 5000 cycles.