Synergistic Molecular and Polymer Network Design Enables Stable LiPF 6 ‐Based Gel Polymer Electrolytes for Lithium Metal Batteries

ABSTRACT High‐voltage lithium metal batteries suffer from severe interfacial degradation and electrolyte decomposition, limiting cycling stability and practical application. In conventional LiPF 6 ‐based electrolytes containing fluoroethylene carbonate (FEC), LiPF 6 decomposition generates Lewis‐acid species that trigger FEC defluorination and HF formation, causing progressive interphase degradation. Here we report a multifunctional gel polymer electrolyte (MGPE) that integrates solvation regulation with polymer‐network confinement and interrupts the PF 5 –FEC degradation pathway via strong PF 6 − binding. The fluorinated aromatic additive 1,1,2,2‐tetrafluoroethoxybenzene modulates the Li + solvation structure and promotes preferential formation of a stable cathode‐electrolyte interphase, enhancing oxidative stability up to 5.0 V. Meanwhile, in situ polymerization of 3,5‐bis(trifluoromethyl)styrene constructs a fluorinated aromatic network with strong affinity toward PF 6 − , suppressing Lewis‑acidic PF 5 formation. The synergistic interplay between solvation regulation, PF 5 suppression, and fluorinated‐network confinement steers interphase evolution toward dense LiF‐rich layers on both electrodes, enabling Li||LiCoO 2 cells to retain 82.6% capacity after 400 cycles at 4.5 V and 90.3% after 200 cycles at a cathode loading of ∼11 mg cm −2 . Furthermore, 1.3 Ah pouch cells (N/P = 1.1) show 80.7% capacity retention after 30 cycles under practical conditions. This work provides an electrolyte‐engineering strategy to suppress PF 5 ‐induced degradation and stabilize interphase evolution, enabling safer high‐energy lithium metal batteries.