No abstract

A novel gel polymer electrolyte based on chitosan with 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4) 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, EMImBF 4 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 EMImBF 4 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.% EMImBF 4 showed good charge-discharge performance and lower electrode/electrolyte interfacial resistance than those of a liquid-phase EMImBF 4 system.