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-BF₄/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.