Polar-Polymer-Enabled Solvent Anchoring Effect Retunes Anion-Dominated Solvation Sheath in Gel Electrolyte

The application of nonflammable gel polymer electrolytes (GPEs) with triethyl phosphate (TEP) solvents is severely impeded by the incompatibility of free TEP molecules on electrode–electrolyte interfaces. Here, to overcome this obstacle, we synthesize an in situ designed GPE (FGPE) by incorporating fluorinated polar−polymer poly-2,2,2-trifluoroethyl methacrylate (PTFMA) into a lithium difluoro(oxalato)borate (LiDFOB)–TEP-based liquid electrolyte. An innovative TEP solvent anchoring effect via dipole–dipole intermolecular chemistry of PTFMA polymer skeleton to TEP solvents is proposed, which breaks the solvation dominance of TEP solvents and facilitates reconstruction of a DFOB–-dominated Li+ solvation sheath, thereby fostering anion-derived interfacial protective layers. Detailed interfacial resistance evolution revealed accelerated interfacial Li+ transport kinetics. Therefore, the Li|FGPE|Li cell achieves a remarkably prolonged cycle life of over 5000 h at 0.1 mA cm–2 and the Li|FGPE|LCO cell demonstrates 90.4% capacity retention after 600 cycles. This work of manipulating the solvent anchoring effect presents different insights into enhancing the interfacial compatibility of GPEs.