Performance of Electric Double-Layer Capacitor with Acidic Cellulose–Chitin Hybrid Gel Electrolyte

An acidic cellulose–chitin hybrid gel electrolyte is prepared from cellulose, chitin, binary ionic liquids, and an aqueous solution for an electric double-layer capacitor (EDLC). The obtained acidic hybrid gel shows a high ionic conductivity of at a room temperature of , which is comparable to of an aqueous electrolyte. The acidic cellulose–chitin hybrid gel electrolyte is applied to an EDLC cell with activated carbon fiber cloths as polarizable electrodes, and its electrochemical performance is investigated by galvanostatic cycling, cyclic voltammetry, and a self-discharge test. The EDLC cell with the acidic cellulose–chitin hybrid gel electrolyte exhibits a higher capacitance and a better cycle life than cells with the reference aqueous electrolyte. The self-discharge measurement suggests that leakage current and potential decay are suppressed by the application of the acidic cellulose–chitin hybrid gel electrolyte. These results indicate that the acidic cellulose–chitin hybrid gel electrolyte has a practical applicability to an advanced EDLC with excellent stability and working performance.