Backbone‐Mediated Coordination‐Environment Reshaping in Gel Polymer Electrolytes for High‐Voltage Lithium Metal Batteries

Conventional linear polyether electrolytes feature abundant ether‐oxygen sites that dominate the primary Li + solvation shell, limiting anion participation and undermining ion transport and high‐voltage stability. A backbone‐mediated coordination‐environment reshaping strategy is proposed by incorporating diglycidyl 1,2‐cyclohexanedicarboxylate (DCD) into the copolymerization of 1,3‐dioxolane (DOL), yielding an in situ crosslinked gel polymer electrolyte, P(DCD‐DOL). The weakly coordinating ester carbonyl groups and the spatially restricted ether‐oxygen sites in the crosslinked network jointly weaken backbone–Li + coordination and promote anion/solvent participation in the Li + solvation shell. Multiscale characterizations and theoretical simulations confirm that P(DCD‐DOL) effectively optimizes the Li + solvation structure, leading to a high Li + transference number of 0.64, an oxidative stability window of 5.20 V, and inorganic‐rich electrode–electrolyte interphases. Consequently, Li||NCM811 cells with P(DCD‐DOL) retain 84.21% capacity after 500 cycles at 4.3 V, and 80.62% after 200 cycles at 4.5 V. Moreover, a 0.9 Ah pouch cell achieves an energy density of 305 Wh kg −1 and retains 82.33% capacity over 180 cycles. This work highlights polymer backbone engineering as an effective route to regulate Li + coordination and interfacial chemistry in high‐voltage lithium metal batteries.