Fluorinated Gel Polymer Electrolytes for Lithium Metal Batteries: From Passive Protection to Adaptive Interfacial...

Lithium metal batteries (LMBs) are promising candidates for next-generation high-energy-density energy storage. However, their practical application is hindered by dendritic lithium growth and unstable electrode-electrolyte interfaces. Fluorinated gel polymer electrolytes (FGPEs) have emerged as attractive electrolyte systems because they combine enhanced safety with liquid-like interfacial contact. Through fluorine-mediated regulation of Li⁺ solvation and interfacial chemistry, FGPEs can improve the stability of lithium metal anodes. This review discusses the transition of FGPEs from passive interfacial protection to dynamic interfacial regulation. A unified framework for designing adaptive interfaces is proposed, emphasizing their ability to respond to electrochemical, mechanical, and ion-transport variations during battery operation. Recent advances in weak intermolecular interactions, molecular interfacial engineering, and functional fillers are summarized with a focus on their roles in regulating solvation structures, interphase chemistry, and Li⁺ transport. Furthermore, emerging insights from operando characterization, multiscale simulations, and multiphysics modeling are discussed to elucidate the dynamic evolution of the solid electrolyte interphase (SEI) and lithium deposition behavior. By linking molecular interactions with interfacial evolution and electrochemical performance, this review provides design principles for developing advanced FGPEs toward practical high-energy-density LMBs.