Regulated Co-Solvation in Gel Polymer Electrolyte Enables Rapid and Selective Li+ Ion Transport for High-Rate Lithium Metal Batteries.

Abstract

The development of gel polymer electrolytes (GPEs) suitable for high-rate lithium metal batteries (LMBs) is urgently needed but remains inherently challenging. This difficulty originates from the competition between the polymer network and the liquid electrolyte for lithium ion (Li+) coordination. Polymer-dominated coordination traps Li+ and slows transport, while solvent-dominated solvation permits uncontrolled anion migration and causes concentration polarization. Here, we resolve this challenge by establishing a matched polymer-electrolyte co-solvation state, which enables rapid and selective Li+ transport via a cooperative mechanism. We implement this concept through a dual-regulated weak-coordination gel polymer electrolyte (DWGPE), which comprises a fluorinated polymer backbone that attenuates Li+ binding, an amide-functionalized crosslinker that immobilizes anions via hydrogen bonding, and a weakly solvating adiponitrile-based liquid phase. Molecular dynamics simulations reveal a cooperative transport mechanism that integrates polymer-assisted hopping and solvent-mediated vehicular diffusion, while suppressing anion mobility. Consequently, Li||DWGPE||LFP coin cells sustain 10 000 cycles at 6 C with 65% capacity retention, corresponding to an ultralow capacity decay of 0.003% per cycle. Our DWGPE also operates stably with high-voltage NCM811 cathodes and in ampere-hour-level pouch cells. This work establishes polymer-electrolyte co-solvation as a design framework for high-performance GPEs toward fast-charging LMBs.