Excellent low temperature performance electrolyte of spiro-(1,1′)-bipyrrolidinium tetrafluoroborate by tunable mixtures solvents for electric double layer capacitor

This paper was addressed on studying the electrolyte for electrochemical double layer capacitors with relatively high ionic conductivity and high electrochemical stability for low temperature application. The data of systematical analysis of the electrochemical characteristics of EDLC have been presented using spiro-(1,1′)-bipyrrolidinium tetrafluoroborate (SBP-BF4) with 1.5 mol L−1 (M) in a variety of solvent compositions including propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), while the mixture solvents are PC+DMC (1:1 in volume) and PC+DMC+EC (1:1:1 in volume). The physical properties and electrochemical performance of SBP-BF4 in all solvent compositions are investigated. It is found that the binary solvent electrolyte systems exhibited better characteristics in electrochemical performance than single and ternary solvent system in low temperature. The capacitance of the binary solvent electrolyte systems could reach about 117.3 F g−1 at 20 °C and 92.3 F g−1 at −50 °C, which were higher than that of single and ternary solvent system. The energy density and power density of EDLCs based on binary solvents systems are can reach 29.6 Wh kg−1 and 12.5 kW kg−1, respectively.