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 H₂O, 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||LiCoO₂ 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 H₂O 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.