Fluorinated Inorganic Solid Electrolytes for Rechargeable Batteries

All solid‐state batteries are becoming increasingly prevalent in recent energy storage research due to their enhanced safety, higher energy density, wider operating temperature ranges, in addition to a longer cycle life compared to standard Li‐ion batteries. Nevertheless, numerous properties require enhancement for this novel technology to reach its full potential, especially the solid electrolyte (SE) field. For example, further research is required in the following areas: ionic conductivity, mechanical properties, and interface stability with the electrolyte and the lithium metal (Li) anode. One proposed approach to enhancing SE properties is fluorination. The incorporation of fluorine can result in enhanced electrochemical stability, attributed to the formation of a lithium fluoride (LiF) interface between the electrolyte and the Li anode. Additionally, fluorine doping can increase ionic conductivity due to its high electronegativity, facilitating the mobility of lithium ions. This review examines the impact of fluorine incorporation on SE properties, focusing on ionic conductivity and electrochemical stability. Furthermore, the limitations of fluorination in electrolytes, particularly with the LiF formation, will be discussed.