Solvation‐Regulated Fluorinated Gel Polymer Electrolyte for Fast Li ⁺ Transport and Interphase Stabilization in Lithium Metal Batteries

ABSTRACT

The development of gel polymer electrolytes (GPEs) with high ionic conductivity and stable electrode/electrolyte interface is crucial for realizing high‐energy‐density lithium metal batteries. In this work, a composite GPE is designed by incorporating 2,2,2‐trifluoroethyl methacrylate (TFEMA) and amino‐functionalized silica (KH550‐SiO ₂ ) to synergistically optimize Li ⁺ transport kinetics and interfacial stability. Through hydrogen‐bonding interactions, the ─NH ₂ groups on KH550‐SiO ₂ regulate the Li ⁺ solvation environment, shifting ion association from ion aggregates (AGGs) toward solvent‐separated ion pairs (SSIPs) and contact ion pairs (CIPs) and restricting TFSI ⁻ mobility, thereby creating a weaker and more dynamic solvation structure with a high Li ⁺ transference number of 0.76 and an ionic conductivity of 1.03 mS cm ⁻¹ . Concurrently, the preferential reductive decomposition of TFEMA and the interfacial reaction of KH550‐SiO ₂ collaboratively induce the formation of a stable solid electrolyte interphase (SEI) rich in LiF and Li ₃ N. Benefiting from these advantages, the Li||LiFePO ₄ full cell achieves a high capacity retention of 85% after 2000 cycles at a high rate of 5 C. This study provides an effective strategy for simultaneously enhancing the bulk Li ⁺ transport and interfacial properties of GPEs through molecular structure design.