高等学校化学学报

高等学校化学学报

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基于氟化硅氧烷溶剂的锂金属电池电解液设计及电化学性能

梁毅, 黄德权, 殷广达, 闻港, 覃维献, 姚远, 韦韬   

  1. 桂林航天工业学院

  • 收稿日期:2025-01-20 修回日期:2025-04-29 网络首发:2025-05-07 发布日期:2025-05-07
  • 通讯作者: 黄德权 E-mail:hdq2535@163.com
  • 基金资助:
    广西高校中青年教师科研基础能力提升项目（批准号：2024KY0808，2022KY0796）资助

Electrolytes Design and Electrochemical Performance for Lithium Metal Batteries Based on Fluorosiloxane Solvents

LIANG Yi, HUANG Dequan, YIN Guangda, WEN Gang, QIN Weixian, YAO Yuan, WEI Tao   

  1. Guilin University of Aerospace Technology
  • Received:2025-01-20 Revised:2025-04-29 Online First:2025-05-07 Published:2025-05-07
  • Contact: HUANG Dequan E-mail:hdq2535@163.com
  • Supported by:
    Supported by the Project on Enhancement of Basic Research Ability of Young and Middle-aged Teachers in Guangxi Universities and Colleges, China(Nos. 2024KY0808, 2022KY0796)

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摘要： 针对锂金属电池存在锂枝晶生长、不稳定的电极/电解液界面及在乙二醇二甲醚（DME）电解液中氧化稳定性差的问题.本文以三甲氧基（3,3,3-三氟丙基）硅烷（TFS）作为电解液溶剂，结合双氟磺酰亚胺锂（LiFSI）锂盐设计了一种新型的氟化硅氧烷电解液.采用密度泛函理论（DFT）计算和分子动力学模拟（MD）分析了电解液的锂溶剂化结构，通过充放电测试、循环性能测试、倍率性能测试对比分析了电池在氟化硅氧烷电解液和DME电解液中的电化学性能，并通过扫描电子显微镜（SEM）和X射线光电子能谱分析仪（XPS）对锂沉积形貌和电极界面成分进行分析.结果表明，TFS中的Si-O键比DME电解液中的C-O键具有更高的键能，这可以增强电解液的氧化稳定性并能够匹配高电压正极材料.TFS溶剂与Li+之间呈现相对较弱的结合能力，这种独特的锂溶剂化结构有利于诱导FSI-阴离子在锂金属负极表面优先分解并形成富含LiF的SEI膜，有效抑制锂枝晶生长并稳定电极界面，并提高锂金属电池的循环寿命.在TFS电解液中，Li||Cu电池在1.0 mA/cm2的电流密度下可以稳定循环300圈，Li||LFP全电池在2.0 C经过400次循环其放电比容量没有出现明显的容量衰减，Li||NCM811全电池在1.0 C经过300次循环后放电比容量保持率仍然达到了83%，显示出优异的循环稳定性.

关键词: 锂金属电池, 氟化硅氧烷溶剂, 电化学性能, 循环稳定性

Abstract: Addressing the issues of lithium dendrite growth, unstable electrode/electrolyte interface, and poor oxidation stability in ethylene glycol dimethyl ether (DME) electrolyte in lithium metal batteries. This work uses trimethoxy (3,3,3-trifluoropropyl) silane (TFS) as the electrolyte solvent and combines with lithium difluorosulfonylimide (LiFSI) salt to design a novel fluorinated siloxane electrolyte. The lithium solvation structure of the electrolyte were analyzed by using density functional theory (DFT) calculations and molecular dynamics simulations (MD). The electrochemical performance of the cells in fluorinated siloxane electrolyte and DME electrolyte were compared and analyzed through charge discharge tests, cycle performance tests, and rate performance tests. The lithium deposition morphology and electrode interface composition were analyzed by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). As a results, the Si-O bond in TFS has a higher bond energy than the C-O bond in DME electrolyte, which can enhance the oxidation stability of the electrolyte and match high-voltage cathode materials. In addition, TFS solvent exhibits relatively weak binding ability with Li+, this unique lithium solvation structure is conducive to inducing FSI- anions to preferentially decompose on the surface of lithium metal anode and form rich-LiF SEI films, effectively inhibiting lithium dendrite growth, stabilizing the electrode interface, and improving the cycle life of lithium metal batteries. In TFS electrolyte, the Li||Cu cell can be stably cycled for 300 cycles at a current density of 1.0 mA/cm2, The Li||LFP full cell showed no significant capacity degradation after 400 cycles at 2.0 C, and the Li||NCM811 full cell maintained a discharge specific capacity retention rate of 83% after 300 cycles at a 1.0 C, demonstrating excellent cycling stability.

Key words: Lithium metal battery, Fluorosiloxane solvent, Electrochemical performance, Cycling stability

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