LiBOB基电解液成膜性及其循环性能

通过循环伏安(CV)、电化学阻抗谱(EIS)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和傅立叶变换红外(FTIR)光谱研究了双乙二酸硼酸锂(LiBOB)基电解液在石墨表面的成膜性及其在常温(25 ℃)和高温(70 ℃)下对石墨循环性能的影响. 结果表明, LiBOB基电解液的成膜电位在1.7 V, 其中BOB-离子还原形成的草酸盐是固体电解质相界面(SEI)膜的有效成分之一. 电化学阻抗谱显示, 膜阻抗在循环过程中呈现减小趋势, 这有利于提高循环稳定性. 在常温和高温条件下, 石墨在该电解液体系中均表现出优于其在LiPF6基电解液体系中的循环性能.

Film Formation and Cycleability of LiBOB-Based Electrolyte

The formation of solid electrolyte interphase (SEI) filmon graphite in a lithiumbis(oxalato)borate (LiBOB)-based electrolyte was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). The effects of SEI filmon the cycleabilities of graphite were examined at roomtemperature (25 ℃) and at high temperature (70 ℃). Results showed that the SEI filmwas formed at around 1.7 V and BOB- ions were reduced to oxalate, which was one of the components of the SEI film. EIS showed that the impedance of the SEI film decreased during the charge/discharge cycle and this was favorable for cycle stability. Whether it was at room temperature or at high temperature, the graphite had better cycleability in the LiBOB-based electrolyte than in the LiPF6-based electrolyte.