双电荷电解质添加剂的低温电化学性能

Low temperature electrochemical properties of double charged electrolyte additives

为了进一步提高超级电容器在低温下的能量密度,制备了双电荷电解质N,N-1,4-二乙基三乙烯基二胺四氟硼酸盐(DEDABCO-BF_(4))。以四乙基铵四氟硼酸盐(TEA-BF_(4))作为电解质,以DEDABCO-BF_(4)为电解质添加剂,二者按照摩尔比9∶1混合,再以碳酸丙烯酯(PC)为溶剂、以乙腈(AN)为共溶剂制备了一系列不同溶剂配比的二元电解液PAXY(X、Y为PC与AN的质量比),通过循环伏安、恒流充放电、交流阻抗等探究了双电荷电解质在低温下的电化学性能。结果表明:PA11电解液组装的超级电容器可在-40℃下实现良好的倍率性能,在2.7 V、5000 mA/g条件下,容量保持率为65%。此外,PA11电解液还进一步将电容器工作电压扩大到3.5 V,获得了110 F/g的比电容、47.87 W·h/kg的最大能量密度和5850 W/kg的最大功率密度。

In order to further increase the energy density of supercapacitors under low temperature,double charged electrolyte N,N-1,4-diethyltrivinyldiamine tetrafluoroborate(DEDABCO-BF_(4))was prepared.Tetraethylammonium tetrafluoroborate(TEA-BF_(4))was used as electrolyte and DEDABCO-BF_(4)was used as electrolyte additive,which were mixed in a molar ratio of 9∶1.Then,a series of binary electrolyte PAXY(X,Y were the mass ratio of PC to AN)with different solvent ratio were prepared with propylene carbonate(PC)as solvent and acetonitrile(AN)as cosolvent.The electrochemical performance of the double charged electrolyte at low temperature has been explored through tests such as cyclic voltammetry,constant current charge and discharge,and AC impedance.The results show that the supercapacitor assembled with PA11 electrolyte can achieve good rate performance at-40℃,and the capacitance retention rate is 65%under the conditions of 2.7 V and 5000 mA/g.In addition,PA11 electrolyte further expands the working voltage of the capacitor to 3.5 V,obtaining a specific capacitance of 110 F/g,a maximum energy density of 47.87 W·h/kg and a maximum power density of 5850 W/kg.