Performance of electrolyte composed of spiro-type quaternary ammonium salt and electric double-layer capacitor using it

Abstract

An electrolyte composed of a tetra-alkyl ammonium cation having a spiro structure (spiro-(1,1')-bipyrrolidinium: SBP) showed excellent performance in terms of electric conductivity, viscosity, and solubility in various solvents, especially propylenecarbonate (PC). The electric double-layer capacitor (EDLC) using spiro-(1,1')-bipyrrolidinium tetrafluoroborate in PC (SBP-BF 4/PC) has a performance better than that using tetraethylammonium tetrafluoroborate in PC (TEA-BF4/PC) and triethylmetylammonium tetrafluoroborate in PC (TEMA-BF4/PC), especially at low temperatures and high discharging rates.