Dihydrogen-bonding interactions in ether-based electrolytes to enable high-voltage lithium metal batteries.

Abstract

High-voltage lithium metal batteries require electrolytes that simultaneously combine oxidative stability with Li metal compatibility, posing a major challenge for conventional ether-based systems, which are typically limited to voltages below 4.0 V. Although conventional electrolyte engineering has been widely employed to enhance oxidative stability, they often compromise ionic conductivity or require complex synthetic routes. Herein, we propose a strategy based on dihydrogen-bonding interactions by introducing 0.05 M LiBH₄ into conventional ether-based electrolytes to construct a dihydrogen-bonded electrolyte. The hydridic H^- in BH₄^- interacts with the active H^δ⁺ atoms of 1,2-dimethoxyethane to form dihydrogen bonds, thereby weakening the Li⁺-solvent interaction, accelerating Li⁺ de-solvation, and promoting uniform Li deposition. Simultaneously, these dihydrogen-bonding interactions shield the active H^δ⁺ sites of the solvent within the positive electrode interface, thereby significantly suppressing the oxidative decomposition of 1,2-dimethoxyethane. As a result, the oxidative stability of the electrolyte is extended to 5.54 V without compromising ionic conductivity (>16 mS cm^-1/30 °C). Lithium metal full cells using this electrolyte exhibit stable cycling at 4.5 V. This study provides a promising pathway for the design of high-voltage ether-based electrolytes.