Electrochemical Behavior of Tetraethylammonium Bis(oxalato)borate in Electric Double-Layer Capacitor Investigated by Using Transmission-Line Model

抄録

Tetraethylammonium bis(oxalato)borate (TEABOB), which is free from halogens, has the potential for use in electric double-layer capacitors (EDLCs). We have used a transmission-line network of finite length as the equivalent circuit of the average pore of an activated carbon electrode and derived the theoretical equation for a constant-current (CC) charge. We evaluated the performance of EDLCs by comparing the theoretical and the experimental charge curves. A 2025-type coin cell using TEABOB showed double-layer capacitance comparable to that obtained for tetraethylammonium tetrafluoroborate (TEABF₄). A very small distance between activated carbon electrodes in the EDLC may compensate for low ionic mobility of TEABOB in the bulk of the solution. The degree of ionic dissociation of TEABOB in the pores of the activated carbon electrode may not be appreciably lower than predicted from the bulk properties of the solution.