Skeletal editing of electrolyte molecule by oxygen-distal fluorination for 500 Wh kg–1, cycling stable Li metal battery

Enhancing cycling reversibility in high-energy-density lithium metal batteries (LMBs) necessitate precise management of electrolyte-derived electrochemical reactions at electrodes and interphases, yet the recently developed and most commonly used localized high-concentration electrolytes (LHCEs) technology suffers from limited tunability on these reactions due to the non-solvation-participating nature of oxygen-proximal fluorinated diluents. Here we address this issue by designing and synthesizing a new oxygen-distal fluorinated diluent. Unlike traditional oxygen-proximal fluorinated analogs, the molecule skeleton was strategically edited to position fluorine atoms distal to oxygen centers that attenuates electron-withdrawing effects at these Li+-coordination sites, enabling: enhanced diluent/anion participation and reduced volatile solvents in solvation shells. This work establishes oxygen-distal fluorination as a new electrolyte molecular skeleton editing principle for stable energy-dense LMBs.

提升高能量密度锂金属电池（LMBs）的循环可逆性，需要精准调控电极与界面处由电解液引发的电化学反应。然而，当前主流且应用最广泛的局部高浓度电解液（LHCEs）技术，由于其邻氧氟化稀释剂不参与溶剂化过程，难以对上述反应实现有效调控。为此，本工作设计并合成了一种新型远氧氟化稀释剂。与传统邻氧氟化类似物不同，本研究通过策略性修饰分子骨架，将氟原子排布于远离氧中心的位置，削弱了锂阳离子（Li+）配位位点处的吸电子效应，从而实现：提升稀释剂与阴离子的参与占比，同时减少溶剂化鞘层内的挥发性溶剂组分。本工作确立了远氧氟化策略作为一种新型电解液分子骨架修饰原则，可用于构建稳定的高能量密度锂金属电池。