Minimizing Solvent-Coordination in Ether Electrolytes for Lithium Metal Batteries under Extreme Operating Conditions

Ether-based electrolytes are considered to be one of the most promising systems for high-performing lithium metal batteries (LMBs). However, the poor oxidation stability (<4.5 V) of ether solvents seriously limit their practical applications. Herein, high-voltage LMBs with LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode operated under extreme conditions by minimizing solvent-coordination in ether electrolytes with fluoroethers, nitrile ethers, and highly fluorinated additives, are demonstrated. It is revealed that ethylene glycol bis(propionitrile) ether (DENE) inhibits the lone-pair electrons loss on ether oxygen through strongly electron-withdrawing cyano groups to increase the electrochemical window to ≥5 V. Heptafluorobutyric anhydride (HFAA) triggers the formation of solid electrolyte interphase rich-in LiF-species, ensuring uniform deposition/stripping and high reversibility of Li⁺. Especially, DENE and HFAA synergistically minimizes the coordination number of ethylene glycol dimethyl ether (DME) and hexafluorophosphate (PF₆ ^-), thereby promoting the desolvation process of Li⁺ and inhibiting the interfacial side reactions. Therefore, the NCM811 cathodes using modified electrolytes exhibit excellent electrochemical performance at ultrahigh voltage (4.7 V), ultrahigh rate (20 C), and ultrawide temperature range (-30 to 120 °C), and achieve stable operation in a high-capacity Li metal pouch cell of 30 Ah and a high-energy density Li metal pouch cell of 502.7 Wh kg^-1, respectively.