Compatibility of Graphite with 1,3-(1,1,2,2-Tetrafluoroethoxy)propane and Fluoroethylene Carbonate as Cosolvents for Nonaqueous Electrolyte in Lithium-Ion Batteries

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• 作者：Guochun Yan ; Xinhai Li ; Zhixing Wang ; Huajun Guo ; Jiexi Wang
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：April 3, 2014
• 年：2014
• 卷：118
• 期：13
• 页码：6586-6593
• 全文大小：503K
• 年卷期：v.118,no.13(April 3, 2014)
• ISSN：1932-7455

文摘

The compatibility of graphite with 1,3-(1,1,2,2-tetrafluoroethoxy)propane (HFE) and fluoroethylene carbonate (FEC) as cosolvents is investigated with Li/graphite cells. Having lower surface tension, HFE can act as a 鈥渟urfactant鈥?to reduce the surface tension of the electrolyte, while FEC increases it. Charge鈥揹ischarge tests validate that the Li/graphite cells show a superior cycling performance and rate ability in 1 M (M = mol L^鈥?) LiPF₆-ethylene carbonate (EC)/ethyl methyl carbonate (EMC)/HFE (mixing ratio: 1/1/1 in weight). Cyclic voltammetry, electrochemical impedance spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy results reveal the mechanism that HFE is reduced with EC together in an EC-based electrolyte, forming a compact surface film at the graphite surface with lower interface resistance compared with FEC. In addition, we proposed that HFE will produce fluoroalkyl lithium compounds (LiOCF₂CF₂CF₂CF₂OLi) through radical termination reaction in the reduction process.