Preparation and Electrochemical Performance of Chitosan-based Gel Polymer Electrolyte Containing Ionic Liquid for Non-aqueous Electric Double Layer Capacitor

Abstract

A novel gel polymer electrolyte based on chitosan with 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) is prepared with a new procedure and applied to electric double layer capacitors (EDLCs). The chitosan-based gel polymer electrolyte causes less liquid leakage than the previous one. In this electrolyte system, EMImBF4 plays the roles of both a solvent for dissolving chitosan and a charge carrier ion for EDLC application. The present chitosan solution for gel polymer electrolytes shows acidity, and its acidity is raised by increasing the amount of EMImBF4 and the preparation temperature. The electrochemical stability of the electrolyte is decreased as the acidity of its chitosan solution increases. At 25°C, an EDLC cell with the electrolyte containing 70 wt.% EMImBF4 showed good charge-discharge performance and lower electrode/electrolyte interfacial resistance than those of a liquid-phase EMImBF4 system.