A Fluoride‐Rich Solid‐Like Electrolyte Stabilizing Lithium Metal Batteries

Abstract To address the problems associated with Li metal anodes, a fluoride‐rich solid‐like electrolyte (SLE) that combines the benefits of solid‐state and liquid electrolytes is presented. Its unique triflate‐group‐enhanced frame channels facilitate the formation of a functional inorganic‐rich solid electrolyte interphase (SEI), which not only improves the reversibility and interfacial charge transfer of Li anodes but also ensures uniform and compact Li deposition. Furthermore, these triflate groups contribute to the decoupling of Li⁺ and provide hopping sites for rapid Li⁺ transport, enabling a high room‐temperature ionic conductivity of 1.1 mS cm⁻¹ and a low activation energy of 0.17 eV, making it comparable to conventional liquid electrolytes. Consequently, Li symmetric cells using such SLE achieve extremely stable plating/stripping cycling over 3500 h at 0.5 mA cm⁻² and support a high critical current up to 2 mA cm⁻². The assembled Li||LiFePO₄ solid‐like batteries exhibit exceptional cyclability for over 1 year and a half, even outperforming liquid cells. Additionally, high‐voltage cylindrical cells and high‐capacity pouch cells are demonstrated, corroborating much simpler processibility in battery assembly compared to all‐solid‐state batteries.