Lithium metal batteries represent a promising technology for next-generation energy storage, but they still suffer from poor cycle life due to lithium dendrite formation and cathode cracking. Fluorinated solvents can improve battery longevity by improving LiF content in the solid–electrolyte interphase; however, the high cost and environmental concerns of fluorinated solvents limit battery viability. Here we designed a series of fluorine-free solvents through the methylation of 1,2-dimethoxyethane, which promotes inorganic LiF-rich interphase formation through anion reduction and achieves high oxidation stability. The anion-derived LiF interphases suppress lithium dendrite growth on the lithium anode and minimize cathode cracking under high-voltage operation. The Li⁺-solvent structure is investigated through in situ techniques and simulations to draw correlations between the interphase compositions and electrochemical performances. The methylation strategy provides an alternative pathway for electrolyte engineering towards high-voltage electrolytes while reducing dependence on expensive fluorinated solvents.

锂金属电池代表了一种有前景的下一代储能技术，但由于锂枝晶的形成和阴极开裂，它们的循环寿命仍然很差。氟化溶剂可以通过提高固体电解质界面中的LiF含量来延长电池寿命；然而，氟化溶剂的高成本和环境问题限制了电池的可行性。在这里，我们通过1,2-二甲氧基乙烷的甲基化设计了一系列无氟溶剂，通过阴离子还原促进无机富LiF界面形成，并实现高氧化稳定性。阴离子衍生的 LiF 中间相可抑制锂阳极上的锂枝晶生长，并最大限度地减少高电压运行下的阴极裂纹。通过原位技术和模拟研究Li ⁺溶剂结构，以得出界面组成和电化学性能之间的相关性。甲基化策略为电解质工程向高压电解质提供了一条替代途径，同时减少了对昂贵氟化溶剂的依赖。