High/low temperature operation of electric double layer capacitor utilizing acidic cellulose–chitin hybrid gel electrolyte

Abstract

An acidic cellulose–chitin hybrid gel electrolyte consisting of cellulose, chitin, 1-butyl-3-methylimidazolium, 1-allyl-3-methylimidazolium bromide, and an aqueous H 2SO 4 solution is investigated for electric double layer capacitors (EDLCs) with activated carbon fiber cloth electrodes. The acidic cellulose–chitin hybrid gel electrolyte shows a high ionic conductivity comparable to that for an aqueous 2 mol dm −3 H 2SO 4 solution at 0–80 °C. This system's temperature dependence in EDLC performance is investigated by galvanostatic charge–discharge measurement. An EDLC cell with the acidic hybrid gel electrolyte has higher capacitance than that with the aqueous H 2SO 4 solution in the range of operation temperatures (−10 to 60 °C). Moreover, the capacitance retention of the EDLC cell with the acidic hybrid gel electrolyte is better than that of a cell with the H 2SO 4 solution at 60 °C over 10,000 cycles. This suggests that the proposed acidic gel electrolyte has excellent stability in the presence of a strong acid, even at a high temperature of 60 °C.