Chem. J. Chinese Universities ›› 2025, Vol. 46 ›› Issue (7): 20250024.doi: 10.7503/cjcu20250024

• Physical Chemistry • Previous Articles     Next Articles

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. College of Automotive Engineering,Guilin University of Aerospace Technology,Guilin 541004,China
  • Received:2025-01-20 Online:2025-07-10 Published:2025-05-07
  • Contact: HUANG Dequan, WEI Tao E-mail:hdq2535@163.com;weitao369369@126.com
  • Supported by:
    the Project on Enhancement of Basic Research Ability of Young and Middle-aged Teachers in Guangxi Universities and Colleges, China(2024KY0808)

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 density functional theory(DFT) 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 scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). As a result, 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+, and this unique lithium solvation structure is conductive to inducing preferentially decompose of FSI anions on the surface of lithium metal anode and forming LiF-rich solid electrolyte interphase(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 shows no significant capacity degradation after 400 cycles at a rate of 2.0C, and the Li 􀰙􀰙 CNCM811 full cell maintains a discharge specific capacity retention rate of 83% after 300 cycles at a rate of 1.0C, demonstrating excellent cycling stability.

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

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