【摘要】 利用量子化学计算、循环伏安、电化学阻抗及充放电测试等方法,考察了电解液成膜添加剂碳酸乙烯亚乙酯(VEC)对锂离子电池性能的影响。量子化学计算结果表明:VEC具有较低的分子最低空轨道(LUMO)能量值。循环伏安及交流阻抗测试表明:碳酸乙烯亚乙酯的还原电位为1.2 V(vs.Li/Li+),优先于电解液在负极表面发生电化学反应形成电解质相界面(SEI)膜。该膜较稳定,可提高电池的循环性能,并抑制电池气胀。SEI膜阻抗较大,不利于电极的嵌脱锂反应,导致首次充放电容量及效率较低。更多还原

【Abstract】 Vinyl ethylene carbonate(VEC) as a film-forming additive for Li-ion battery was investigated by quantum chemical calculation,cyclic voltammetry,electrochemical impedance spectroscopy and discharge-charge tests.The result of quantum chemical calculation showed that the VEC had lower lowest unoccupied molecular orbital(LUMO) energy value.The electrochemical reduction potential of VEC was about 1.2 V(vs.Li/Li+),much higher than that of solvents of electrolyte,this reaction produced solid electrolyte interface(SEI) film on the anode.Because of the stable SEI film,VEC was capable of improving the cycle performance,preventing the gas generation of battery.The impedance of SEI formed in VEC-electrolyte was higher than that of blank sample,which was not suitable for intercalation-deintercalation reactions and led to lower initial charge-discharge capacity and efficiency.更多还原