电解液添加剂硫酸亚乙酯对锂离子电池性能的影响

在1 mol/L LiPF₆/碳酸乙烯酯+碳酸二甲酯+碳酸甲乙酯（体积比1∶1∶1）电解液中，采用恒流充放电测试、循环伏安法（CV）、扫描电子显微镜（SEM）、能量散射光谱（EDS）、电化学阻抗谱（EIS）等测试技术，研究了添加剂硫酸亚乙酯（DTD）对锂离子电池性能及石墨化中间相碳微球（MCMB）电极/电解液界面性质的影响。 结果表明，在电解液中引入体积分数0.01%DTD后，MCMB/Li电池可逆放电容量从300 mA·h/g提高至350 mA·h/g，电池总阻抗降低，循环稳定性提高。CV测试发现，在首次还原过程中，DTD在电极电位1.4 V左右（vs Li/Li⁺）发生电化学还原，参与了MCMB电极表面固体电解质相界面膜（SEI膜）的形成过程。 同时，DTD对LiMn₂O₄电极性能无不良影响。

Effect of Ethylene Sulfate as Electrolyte Additive on Performance of Li-ion Batteries

Ethylene sulfate(DTD) was studied as an additive to 1 mol/L LiPF₆/ethylene carbonate(EC)+dimethyl carbonate(DMC)+methyl ethyl carbonate(EMC)(1∶1∶1 by volume) electrolyte for lithium ion batteries. The effects of DTD on lithium ion battery performance and on the mesocarbon microbead(MCMB) electrode/electrolyte interphase were investigated by galvanostatic charge-discharge measurements, cyclic voltammetry(CV), scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and electrochemical impedance spectroscopy(EIS). The results show that DTD with a volume ratio of 0.01% can increase the reversible discharge capacity(from 300 mA·h/g to 350 mA·h/g) and cycleability of MCMB/Li cell. SEM observation and EIS analysis suggest that DTD facilitates the morphology of solid electrolyte interface(SEI) formed on the surface of the MCMB electrode and reduces the total resistance of the cell. CV measurements reveal that DTD can be electrochemically reduced at potentials around 1.4 V(vs Li/Li⁺) during the first reduction engaged in the formation of SEI. At the same time, DTD has no adverse effect on the LiMn₂O₄ electrode.