Heterogeneous Doping via Methyl‐Encapsulated Fumed Silica Enabling Weak Solvated and Self‐Purified Electrolyte in Long‐Term High‐Voltage Lithium Batteries

Abstract Crafting a sustainable non‐aqueous electrolyte is paramount in the pursuit of high‐voltage lithium batteries that exhibit exceptional performance. Traditional carbonate‐based electrolytes encounter hurdles in maintaining electrochemical stability due to unstable interphases, as well as continuous degradation of the electrolyte itself. Herein, based on heterogeneous doping, a colloidal electrolyte with multiple functions via simple integrating methyl‐encapsulated fumed silica (MFS) into a conventional carbonate‐based electrolyte effectively addresses the aforementioned challenges. The produced colloidal electrolyte endowed with unexpected self‐purification capabilities effectively eliminates HF and H 2 O, consequently enhancing stability of the electrolyte, interphase, and electrode. Furthermore, MFS induces a weakly solvated Li + structure that is heterogeneously doped into the original solvation matrix and contributes to the formation of tailored and stable electrode/electrolyte interphases for both anode and cathode. Using such electrolyte, Li||LiCoO 2 batteries demonstrate capacity retentions of 83.6% and 95.4% within 3000 and 1000 cycles at charging voltages of 4.4 and 4.5 V, respectively. Remarkably, with addition of 2000 ppm H 2 O in this electrolyte, cells can be cycled stably over 400 cycles with a capacity retention of 88.6%. This simple and effective electrolyte engineering strategy has the sustainability to significantly advance the development of highly stable high‐voltage lithium batteries.