Synergistic Additives Enabling Stable Cycling of Ether Electrolyte in 4.4 V Ni-Rich/Li Metal Batteries

Ether-based electrolytes have high ionic conductivity and good stability toward the lithium metal anode relative to carbonate-based electrolytes, but they typically exhibit poor oxidation stability (<4 V vs Li + /Li). Most approaches aimed at enhancing the oxidative stability of ether-based electrolytes, such as “salt-in-solvent” and “weakly solvating” strategies, often sacrifice their inherent advantage of high ionic conductivity. Herein, this article proposes a cost-effective synergistic additive strategy by co-adding LiNO 3 and vinylene carbonate (VC) to achieve an optimized ether-based electrolyte (OEE) that simultaneously offers high Li-ion (Li + ) conductivity (11.52 mS cm −1 at 20 °C) and high-voltage stability (4.4 V). LiNO 3 and VC can enter the inner solvation shell of the electrolyte, preferentially participating in the film-forming progress at the electrode surface, leading to the formation of a unique organic–inorganic bilayer interfacial protective layer. This layer could effectively suppress electrolyte side reactions and enhance electrode stability. As a result, the 4.4 V Li-LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NCM811) full cells assembled with the OEE exhibit stable cycling performance at both room temperature and low temperature. This work provides a new approach to the design of ether-based electrolytes for high-voltage lithium metal batteries.