丁磺酸内酯对锂离子电池性能及负极界面的影响

Effect of Butyl Sultone on the Li-ion Battery Performance and Interface of Graphite Electrode

用循环伏安(CV)、电化学阻抗谱(EIS)、扫描电镜(SEM)、能谱分析(EDS)及理论计算等方法研究了添加剂丁磺酸内酯(BS)对锂离子电池负极界面性质的影响.研究表明,在初次循环过程中,BS具有较低的最低空轨道能量,优先于溶剂在石墨电极上还原分解,并形成固体电解质相界面膜(SEI膜).在含BS的电解液中形成的SEI膜的热稳定性高,在70℃下储存24h后,膜电阻和电荷迁移电阻大小基本保持不变,而在不含BS的电解液中形成的SEI膜的热稳定性较差,在70℃下储存24h后,膜电阻和电荷迁移电阻大小有明显的增加.从BS对锂离子电池电化学性能影响的研究表明,加入少量的BS能够显著提高锂离子电池的室温放电容量、低温及高温储存放电性能.

Effect of butyl sultone （BS） on the graphite interface of lithium ion battery in carbonate-based electrolytes is studied by cyclic voltammetry （CV）, electrochemical impedance spectroscopy （EIS）, scanning electron microscopy （SEM）, energy dispersive spectroscopy（EDS）, as well as the density functional theory（DFT） calculation. The results indicate that BS has lower LUMO energy than the solvents and is reduced prior to solvent compositions of the electrolyte on graphite electrode, forming a stable solid electrolyte interface（SEI） film during the first cycle. The SEI film resistance and the charge transfer resistance of graphite electrode in BS containing solution change little after storage at 70 ℃ for 24 h, while those in BS-free solution increase significantly. The influence of BS on the electrochemical performance was also discussed. It was found that the discharge capacities at room temperature, low temperature and after high temperature storage were significantly improved due to the presence of BS.