Boron Crosslinking Enables Anion-Lean Solvation and Stable Interfaces for Dendrite-Free Lithium Metal Batteries.

Abstract

Achieving high-performance and safe lithium metal batteries (LMBs) requires electrolytes that simultaneously optimize solvation chemistry, interfacial stability, ionic conductivity, and mechanical robustness. Conventional gel polymer electrolytes (GPEs) often suffer from low lithium-ion transference numbers and sluggish interfacial kinetics because mobile anions and strong Li+ solvation induce concentration polarization and dendritic Li growth. Herein, we design a sp2-hybridized boron-crosslinked gel polymer electrolyte (GPE_TMAB) that integrates anion-lean solvation and interfacial engineering within a single platform. GPE_TMAB is constructed from a boron-containing multi-arm crosslinker (TMAB), methyl ether acrylate, and isobornyl acrylate, together with a binary ethyl methyl carbonate/fluoroethylene carbonate solvent system that balances strong coordination and facile desolvation, thereby establishing soft, Li+-dominant solvation environments. Molecular dynamics simulations reveal that the boron-mediated TFSI- trapping weakens Li+ solvation and enhanced Li+ diffusion. Accordingly, Lewis-acidic boron centers enable Li+ single-ion conduction and promote formation of a mechanically robust, inorganic-rich SEI. GPE_TMAB achieves high ionic conductivity, intrinsic non-flammability, dendrite-free Li plating/stripping for over 1200 h, and durable LFP∥Li full-cell cycling with 86% capacity retention after 800 cycles, with improved transport kinetics and stable interfacial chemistry. This work establishes a boron-enabled solvation and interfacial design strategy for high-voltage, dendrite-free, and safe all-solid-state LMBs.

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