The electric double layer (EDL) plays a pivotal role in the interfacial reactions that occur within lithium batteries. However, theoretical models beyond the empirical Guy-Chapman-Stern (GCS) model to understand reaction mechanisms and tuning principles are lacking. Herein, we introduce a quantitative parameter of region d within the EDL, which successfully elucidates the correlation between the EDL functional domain and the oxidation resistance of electrolytes. The reduced spatial scale of d results in a rapid decay of interface potential to the bulk level, effectively suppressing the continuous decomposition of the electrolyte. By precisely modulating the functional area represented by d, the designed 1.5 M LiFSI in a (3,3,3-Trifluoropropyl) trimethoxysilane (TFTMS) electrolyte exhibits remarkably high oxidation stability of >5.5 V and enables simultaneous stabilization of Li metal, graphite, and high-voltage layered cathodes. The EDL model incorporated with quantitative functional area d offers a promising path to guide the advancement of high-energy Li batteries.

双电层（EDL）在锂电池内发生的界面反应中起着关键作用。然而，除了经验盖伊-查普曼-斯特恩 (GCS) 模型之外，还缺乏用于理解反应机制和调节原理的理论模型。在这里，我们引入了 EDL 内d区的定量参数，成功地阐明了 EDL 功能域与电解质抗氧化性之间的相关性。d空间尺度的减小导致界面电位快速衰减至体水平，有效抑制电解质的连续分解。通过精确调节d代表的功能区域，在 (3,3,3-三氟丙基) 三甲氧基硅烷 (TFTMS) 电解质中设计的 1.5 M LiFSI 表现出 >5.5 V 的极高氧化稳定性，并能够同时稳定锂金属、石墨、和高压层状阴极。结合定量功能区d 的EDL 模型为指导高能锂电池的发展提供了一条有希望的道路。