High-Elastic Flame-Retardant Polyacrylate-Based Gel Polymer Electrolyte by Dual-Phase Fluorination for Highly Stable Lithium-Metal Batteries

Lithium-metal batteries (LMBs) are emerging as promising energy storage devices due to their exceptional energy densities. However, uncontrolled lithium dendrite growth and the flammability of liquid electrolytes heavily hinder their widespread applications. To circumvent such issues, we develop a dual-phase fluorinated gel polymer electrolyte (TF-GPE), composed of a fluorinated framework polymerized by 2,2,2-trifluoroethyl acrylate and a fluorinated solvent with fluoroethylene carbonate. The resulting TF-GPE exhibits an impressive tensile elasticity and volumetric accommodations of repeated lithium deposition and stripping up to 4000 h. Additionally, TF-GPE demonstrates excellent flame retardancy by forming a dense fluorine-containing carbon layer. By analyzing the surface of cycled lithium metal, we reveal the formation of elastic solid electrolyte interphase structures with outer organic and inner LiF-rich inorganic layers, enabling stable cycling of 500 cycles with 80.5% capacity retention for solid-state LMBs at 1 C. Our work presents a promising approach to enhancing the stability of LMBs.