Non-aqueous electrolyte solvents play a pivotal role in improving the cycling performance of high-voltage Li-rich Mn-based layered cathode materials. In this study, a fluoroether (1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, TFEPE) was added to 1.2 mol·L−1 LiPF6 EC/EMC/DEC at different concentrations to synthesize a series of electrolytes for enhancing the cycling performance of high-voltage Li1.18Mn0.50Ni0.26Co0.06O2 (LMNC). Effects of TFEPE on the electrochemical performance of LMNC at 0.1C and 1.0C rates were investigated. Scanning electron microscopy was used to observe the surface morphology of LMNC before and after cycling. X-ray photoelectron spectroscopy was conducted to analyze the surface compositions and chemical states, and transmission electron microscopy was performed to directly examine the changes in the structure of LMNC before and after cycling. Results suggested that TFEPE was preferentially oxidized and produced inorganic compounds (MeF and Li2CO3) on the surface of LMNC, which effectively inhibited the side reactions between LMNC and the electrolyte. MeF and Li2CO3 delayed the propagation of the phase transitions of LMNC primary particles from the surface to the bulk, thereby improving the cycling performance of LMNC.

中文翻译：

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1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚与高电压富锂锰基层状正极材料的界面稳定性

非水电解质溶剂在提高高电压富锂锰基层状正极材料的循环性能方面发挥着关键作用。本研究将氟醚（1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚，TFEPE）添加到不同浓度的1.2 mol·L-1 LiPF6 EC/EMC/DEC中合成一系列用于提高高压 Li1.18Mn0.50Ni0.26Co0.06O2 (LMNC) 循环性能的电解质。研究了 TFEPE 在 0.1C 和 1.0C 速率下对 LMNC 电化学性能的影响。使用扫描电子显微镜观察循环前后LMNC的表面形貌。进行X射线光电子能谱分析表面成分和化学状态，并通过透射电子显微镜直接检查循环前后LMNC结构的变化。结果表明，TFEPE优先氧化并在LMNC表面生成无机化合物（MeF和Li2CO3），有效抑制了LMNC与电解液的副反应。MeF 和 Li2CO3 延迟了 LMNC 初级粒子从表面到体相的相变传播，从而提高了 LMNC 的循环性能。