Temperature Dependence of Electric Double-Layer Capacitor Operation Utilizing Acidic Cellulose-Chitin Hybrid Gel Electrolytes

An acidic cellulose-chitin hybrid gel electrolyte consisting of cellulose, chitin, 1-butyl-3-methylimidazo lium, 1-ally1-3-methylimidazo hum bromide, and an aqueous H2SO4 solution is investigated for electric double layer capacitors (EDLCs). This gel electrolyte shows a high ionic conductivity comparable to that observed in an aqueous 2 mol dm(-3) H2SO4 solution in 0-80 degrees C. An EDLC cell with the acidic hybrid gel electrolyte has higher capacitance than that with an aqueous H2SO4 solution in the operation temperature (-10-60 degrees C). Moreover, the capacitance retention of the EDLC cell with the acidic hybrid gel electrolyte is better than a cell with a H2SO4 solution at 60 degrees C over 10,000 cycles. This suggests that the present acidic gel electrolyte has excellent stability in the presence of a strong acid even at a high temperature of 60 degrees C.