Our work on monofluoroether electrolyte design and its unique solvent-based interfacial chemistry has been accepted by JACS Au! Congrats to Digen and Lijiang!

Electrolytes are critical for the reversibility of various electrochemical energy storage systems. Recent development of electrolytes for high-voltage Li-metal batteries has been counting on the salt anion chemistry for building stable interphases. Herein, we investigate the effect of solvent structure on the interfacial reactivity and discover profound solvent chemistry of designed monofluoro-ether in anion-enriched solvation structures, which enables enhanced stabilizations of both high-voltage cathode and Li metal anode. Systematic comparison of different molecular derivatives provides atomic-scale understanding of the unique solvent structure-dependent reactivity. The interaction between Li⁺ and the monofluoro (-CH₂F) group significantly influences the electrolyte solvation structure and promotes the monofluoro-ether based interfacial reactions over the anion chemistry. With in-depth analyses of the compositions, charge transfer and ion transport at interfaces, we demonstrated the essential role of the monofluoro-ether solvent chemistry in tailoring highly protective and conductive interphases (with enriched LiF at full depths) on both electrodes, as opposed to the anion-derived ones in typical concentrated electrolytes. As a result, the solvent-dominant electrolyte chemistry enables high Li Coulombic efficiency (~99.4%) and stable Li anode cycling under high rate (10 mA cm^-2), together with greatly improved cycling stability of 4.7 V-class nickel-rich cathodes. This work illustrates the underlying mechanism of competitive solvent and anion interfacial reaction schemes in Li-metal batteries and offers fundamental insights into the rational design of electrolytes for future high-energy batteries.