Dramatic Improvements in Electric Double-Layer Capacitors by Using Polysaccharides

Abstract

A nonaqueous solid-state electrolyte based on an alginate (Alg) with a conventional supporting electrolyte was prepared for use in electric double layer capacitors (EDLCs). According to the charge/discharge measurements, despite the use of a solid-state electrolyte, the model EDLC cells containing the Alg-based electrolyte possessed a higher discharge capacitance than the corresponding solution-based electrolyte, which implies that the high affinity of Alg for activated carbon electrodes decreases the electrode/electrolyte interfacial resistance. Because of its good affinity for carbon materials, we also applied Alg as a binder to an activated carbon-based composite electrode. The test cells with the composite electrodes containing Alg demonstrated a remarkably powerful EDLC performance using both a conventional organic-solution-based electrolyte and a highly viscous ionic liquid electrolyte.