Solvation‐Preserving Gelation of Localized High‐Concentration Electrolytes for Lithium Metal Batteries

Abstract

ABSTRACT Localized high‐concentration electrolytes (LHCEs) exhibit excellent interfacial compatibility with lithium metal anodes and high‐nickel cathodes, whereas the introduction of polymer networks during gelation may alter their intrinsic solvation structures. Here, we report a solvation‐preserving gel electrolyte formed via in situ polymerization of a fluorinated polymer network within a 1,2‐Dimethoxyethane (DME)‐based LHCE. Unlike conventional gel polymer electrolytes, the fluorinated polymer exhibits limited Li + coordination, thereby largely preserving the localized high‐concentration solvation environment during gelation. This design couples the preserved LHCE solvation chemistry with a fluorinated polymer framework, enabling synergistic regulation of electrode–electrolyte interfaces and enhanced electrochemical performance. Meanwhile, the fluorinated polymer network further improves safety by reducing electrolyte flammability. Lithium symmetric cells achieve stable cycling over 2000 h, while LiNi 0.9 Co 0.05 Mn 0.05 O 2 (NCM9)|Li full cells deliver 82.2% capacity retention after 300 cycles and operate stably up to 4.5 V. At the pouch‐cell level, a gravimetric energy density of 394.3 Wh kg −1 is achieved under lean‐electrolyte conditions, while no thermal runaway is observed up to 300°C. This work demonstrates that preserving solvation structure via rational polymer network design enables simultaneous improvements in interfacial stability, safety, and practical performance in quasi‐solid‐state lithium metal batteries.