A novel quaternary ammonium salt based on spiro-(1,10)-bipyrolidinium tetrafluoroborate
(SBP-BF4) has been synthesized and dissolved in propylene carbonate (PC) with
1.5 mol/L (M) concentration for electric double-layer capacitors (EDLCs). The
physic-chemical properties and electrochemical performance of SBP-BF4/PC
electrolyte are investigated. Compared with the standard electrolyte1.5 MTEMABF4
inPC, the novel SBP-BF4/PC electrolyte exhibited much better
electrochemical performance due to its smaller cation size, lower viscosity and
higher conductivity. The specific discharge capacitance
of activated carbon electrode based EDLCs using SBP-BF4/PC electrolyte is120 F/g, the energy density and power density
can reach 31 kW/kg and 6938 W/kg, respectively, when the working voltage is 2.7
V and current density is 50 mA/g. The withstand voltage of activated carbon
based EDLCs with SBP-BF4/PC electrolyte can reach to 3.2 V, where the stable
discharge capacitance and energy density are121 F/g and 43 Wh/kg, respectively.
