Polyacrylonitrile and 1-Ethyl-3-Methylimidazolium Thiocyanate Based Gel Polymer Electrolyte for Solid-State Supercapacitors with Graphene Electrodes

Abstract

A novel ionic liquid gel polymer electrolyte based on low viscosity ionic liquid 1-ethyl-3-methylimidazolium thiocyanate (EMImSCN) entrapped in polyacrylonitrile (PAN) has been prepared for its application as an electrolyte in supercapacitors. The gel polymer electrolyte shows high ionic conductivity of ~ 1 x 10-3 S cm-1 at room temperature. The solid-state supercapacitors have been fabricated with graphene electrodes and gel polymer electrolyte films. The performance characteristics have been studied by ac impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge techniques. The maximum overall cell capacitance value is observed to be 144 mF cm-2 which is equivalent to a single graphene electrode specific capacitance of 137 F g-1. The solid-state supercapacitor cell shows specific energy of ~4.7 W h kg-1 and specific power of ~4.1 kW kg-1. The gel polymer electrolyte based supercapacitor cell shows excellent cyclic performances for more than 2000 cycles.