电解质离子尺寸对超级电容器电化学性能的影响

Influence of size of electrolyte ion on the electrochemical performance of supercapacitor

为了研究电解质离子尺寸对超级电容器电解液电化学性能的影响,自制了阳离子不同的2种电解质N,N-二甲基吡咯烷四氟硼酸盐(P_(11)-BF_4)和N-乙基-N-甲基吡咯烷四氟硼酸盐(P_(12)-BF_4),并分别配制成以碳酸丙烯酯(PC)为溶剂、浓度为1 mol/L的电解液;通过循环伏安、恒流充放电、交流阻抗谱研究了电解质离子尺寸对活性炭基超级电容器电化学性能的影响。结果表明:电解质离子尺寸和阳离子对称性共同影响着超级电容器的放电比电容,电解质离子尺寸越小,电解液的耐电压特性越好,超级电容器的工作电压越高;电解质离子尺寸的大小和阳离子的对称性共同影响着超级电容器的电化学性能。

In order to study the influence of the size of electrolyte ions on the electrochemical performance of supercapacitor electrolyte,two kinds of electrolytes,N,N-dimethylpyrrolidinium tetrafluoroborate(P11-BF4),N-ethyl-N-methylpyrrolidinium tetrafluoroborate(P12-BF4),are synthesized.The electrolyte salts were arranged into propylene carbonate(PC)with the concentration of 1 mol/L.The influence of the size of electrolyte ion on the electrochemical performance of activated carbon based supercapacitors were investigated by cyclic voltammetry,constant current charge-discharge and AC impedance spectroscopy.The results show that both the electrolyte ion size and cation symmetry affect the discharge specific capacitance of the supercapacitors.The smaller the electrolyte ion size is,the better the voltage withstanding characteristic of the electrolyte is,and the higher the working voltage of the supercapacitor is.The size of the electrolyte ion and the symmetry of the cation affect the electrochemical performance of the supercapacitors.