使用成膜添加剂ES的锂离子电池的性能

Performance of Li-ion battery using film-forming additive ES

通过量子化学计算、循环伏安、电化学阻抗及充放电测试,考察电解液成膜添加剂亚硫酸乙烯酯(ES)对锂离子电池性能的影响。ES的最低空轨道(LUMO)能量较低,还原电位为1.8 V(vs.Li/Li+),将优先于电解液在负极表面发生反应,形成较致密稳定的固体电解质相界面(SEI)膜。SEI膜可降低不可逆容量,提高电池的循环性能;Li+在SEI膜与活性物质界面的电荷转移阻力较小,可提高电池在低温下的放电容量。SEI膜的阻抗较大,会降低首次充放电容量。

Ethylene sulfite（ES） as a film-forming additive for Li-ion battery was investigated by quantum chemical calculation, cyclic vohammetry, electrochemical impedance spectroscopy and discharge-charge tests. The lowest unoccupied molecular orbital（LUMO） energy of ES was lower,the reduction potential was 1.8 V （vs. Li/Li^＋） ,the reaction would occur on the surface of anode before electrolyte and form a stable solid electrolyte interface（SEI）film. SEI film could reduce irreversible capacity and improve cycle performance of battery. The charge transfer resistance of Li ＋ between SEI film and active material interface was lower, which could increase discharge capacity of battery at low temperature. The impedance of SEI film was higher,would lead to lower initial charge-discharge capacity.