Thermal and Electrolytic Properties of Quaternary Ammonium Salts Based on Fluorine-Free Chelatoborate Anions and Their Application to EDLCs

摘要

The use of bis(oxalato)borate ion makes it possible to increase the solubility of the tetramethylammonium salt in propylene carbonate (PC). We have investigated the thermal and electrolytic properties of tetrarnethylammonium bis(oxalato)borate (TMA-BOB), tetraethylammonium bis(oxalato)borate (TEABOB), and tetraethylammonium bis[salicylato(2-)]borate and their application to electric double-layer capacitors (EDLCs). The anion sizes of the fluorine-free chelatoborates are larger than that of tetrafluoroborate, and the ionic conductivities and wettability of the PC solutions become lower. Nevertheless, the gravimetric capacitances of model cells using the TMABOB and the TEABOB are comparable to that obtained for tetraethylammonium tetrafluoroborate (TEABFA