Anionic Solvation Transition at Low Temperatures for Reversible Anodes in Lithium–Oxygen Batteries

Li-O₂ batteries provide a novel technology for electric energy storage due to their high energy density. However, the strong solvent coordination with Li⁺ at low temperatures impacts their performance and triggers irreversible interfacial reactions on the Li anode. Herein, cyclopentyl methyl ether (CME) is incorporated in a dimethoxyethane (DME)-based electrolyte to realize an anionic solvation transition at low temperatures in Li-O₂ batteries. CME featuring a single O coordination site substitutes highly solvating DME in the first solvation sheath, and it induces more anion coordination to Li⁺ across the room- and low-temperature ranges. The low residence time of CME (66 ps at 25 °C, 382 ps at -40 °C.) in the solvation structures leads to the fast exchange of coordinated CME molecules with Li⁺ in comparison with DME and facilitates Li⁺ desolvation at low temperatures. The simultaneously generated inorganic-rich solid electrolyte interphase promotes Li⁺ transport to improve Li deposition and suppress Li dendrite formation. These enable the Li-O₂ battery to present a good cycling stability of 110 cycles with a fixed capacity of 1000 mA h g^-1 at -40 °C. This work paves the way for designing novel electrolytes in low-temperature batteries.