Synergistic Molecular and Polymer Network Design Enables Stable LiPF6-Based Gel Polymer Electrolytes for Lithium Metal Batteries.

High-voltage lithium metal batteries suffer from severe interfacial degradation and electrolyte decomposition, limiting cycling stability and practical application. In conventional LiPF6-based electrolytes containing fluoroethylene carbonate (FEC), LiPF6 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 PF5-FEC degradation pathway via strong PF6 - 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 PF6 -, suppressing Lewis‑acidic PF5 formation. The synergistic interplay between solvation regulation, PF5 suppression, and fluorinated-network confinement steers interphase evolution toward dense LiF-rich layers on both electrodes, enabling Li||LiCoO2 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 PF5-induced degradation and stabilize interphase evolution, enabling safer high-energy lithium metal batteries.