LiODFB基电解液对锂离子电池性能的影响
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摘要
通过循环伏安(CV)、扫描电子显微镜(SEM)、电化学阻抗谱(EIS)和恒电流充放电测试方法研究了二氟草酸硼酸锂(LiODFB)基电解液对Li/石墨半电池和镍锰酸锂(LiNi_(0.5)Mn_(1.5)O_4)/石墨全电池性能的影响。结果表明,在首次循环过程中,Li ODFB约在1.5 V在石墨电极表面还原,形成初始固体电解质相界面膜(SEI),阻止电解液与石墨电极的直接接触,电解液在石墨电极表面的还原得以减少,从而在石墨电极表面形成了致密低阻抗的SEI膜,提高了Li/石墨半电池和LiNi_(0.5)Mn_(1.5)O_4/石墨全电池的循环性能。
The performance of Li/graphite half-cell and Li Ni0.5 Mn1.5 O4/graphite full-cell in a lithium difluoro(oxalato)borate(LiODFB)-trifluoropropylene carbonate(TFPC)-dimethyl carbonate(DMC) electrolyte was investigated by cyclicvoltammetry(CV), scanning electron microscope(SEM), electrochemical impedance spectroscopy(EIS) andgalvanostatic charge-discharge cycling technique. The results show that Li ODFB is reduced on the graphiteelectrode at around 1.5 V in the first cycle, the preliminary SEI film is formed, and then the direct contact betweenelectrolyte and graphite electrode. Thus the reduction of electrolyte on the surface of graphite electrode is reduced;then a compact and low resistance SEI film is formed on the graphite electrode, and the cycling performance ofLi/graphite half-cell and Li Ni0.5 Mn1.5 O4/graphite full-cell are improved.
The performance of Li/graphite half-cell and Li Ni0.5 Mn1.5 O4/graphite full-cell in a lithium difluoro(oxalato)borate(LiODFB)-trifluoropropylene carbonate(TFPC)-dimethyl carbonate(DMC) electrolyte was investigated by cyclicvoltammetry(CV), scanning electron microscope(SEM), electrochemical impedance spectroscopy(EIS) andgalvanostatic charge-discharge cycling technique. The results show that Li ODFB is reduced on the graphiteelectrode at around 1.5 V in the first cycle, the preliminary SEI film is formed, and then the direct contact betweenelectrolyte and graphite electrode. Thus the reduction of electrolyte on the surface of graphite electrode is reduced;then a compact and low resistance SEI film is formed on the graphite electrode, and the cycling performance ofLi/graphite half-cell and Li Ni0.5 Mn1.5 O4/graphite full-cell are improved.
引文
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[3] ZHANG Z C, HU L B, WU H M, et al. Fluorinated electrolytes for5 V lithium-ion battery chemistry[J]. Energy&Environmental Sci-ence, 2013, 6(6):1806-1810.
[4] ZHANG S S. An unique lithium salt for the improved electrolyteof Li-ion battery[J]. Electrochemistry Communication, 2006, 8(9):1423-1428.
[5] ZHANG S S. Electrochemical study of the formation of a solidelectrolyte interface on graphite in a LiBC2O4F2-based electrolyte[J]. Journal of Power Sources, 2007, 163(2):713-718.
[6] FU M H, HUANG K L, LIU S Q, et al. Lithium difluoro(oxalato)borate/ethylene carbonate+propylene carbonate+ethyl(methyl)car-bonate electrolyte for LiMn2O4cathode[J]. Journal of PowerSources, 2010, 195(3):862-866.