Molecular Engineering of Fluorinated Hybrid Gel Polymer Electrolytes Enables Ultra‐Wide‐Temperature Operation of High‐Voltage Lithium Metal Batteries

The development of wide-temperature gel polymer electrolytes (GPEs) represents a promising strategy for enhancing the extreme environment tolerance of lithium-metal batteries (LMBs), which requires simultaneously optimizing Li+ transport kinetics at low temperatures and maintaining the thermal and mechanical stability. This work addresses the intrinsic limitations of conventional GPEs by employing a molecular engineering strategy that achieves molecular-scale hybridization of organic and inorganic units. Specifically, a fluorinated hybrid gel polymer electrolyte (FHPE) is fabricated through the in situ crosslinking polymerization of trifluoroethyl acrylate (TFEA) and acryloxypropyl polyhedral oligomeric silsesquioxane (Acry-POSS) within 2,2-difluoroethyl acetate (DFEA). The FHPE displays high Li$^+$ conductivity (3.54 × 10$^{−4}$ S cm$^{−1}$ at −30°C), broad electrochemical stability window (>4.7 V), and remarkable mechanical strength (58.7 MPa). Moreover, the FHPE promotes the formation of LiF-rich interphases on the LiCoO$_2$ cathode and lithium metal anode, thereby effectively mitigating dendrite growth and interfacial side reactions. ... mehrConsequently, FHPE-based Li/Li coin cells stably cycle for 1500 h at 0.3 mA cm$^{−2}$ and −30°C, while Li/LiCoO$_2$ coin cells exhibit 86.7% capacity retention after 200 cycles at −30°C and 77.9% after 400 cycles at 60°C. Furthermore, Li/FHPE/LiCoO$_2$ pouch cells exhibit stable operation during nail penetration tests, thereby confirming their exceptional safety.