Electrochemical Characterization of Activated Carbon‐Fiber Cloth Polarizable Electrodes for Electric Double‐Layer Capacitors

Electrochemical characterization has been carried out for two types of phenolic resin‐based activated carbon‐fiber cloths (ACFC)—ACFC(a) and (b)—as polarizable electrodes. The specific surface areas of ACFC(a) and ACFC(b) were 1630 and 1060 m 2 g −1 , respectively. The differential capacitance of ACFC(a) in organic electrolyte, which was determined by cyclic voltammetry, was 113 F g −1 at 0.1 V vs. SCE. The capacitive current of ACFC(a) was almost constant in the range between −1.5 and 1.5V vs. SCE at 25° and −25°C, while that of ACFC(b) decreased under cathodic polarization, especially at −25°C. In accordance with the result of cyclic voltammetry, the temperature dependence of capacitance in the electric double‐layer capacitors with ACFC(a) and an organic electrolyte was small, and that of the capacitors with ACFC(b) was large. It was found that the temperature dependence of the capacitors with ACFC and an organic electrolyte was mainly influenced by the pore size distribution of ACFC electrodes.