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

Li-O 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-O 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-O battery to present a good cycling stability of 110 cycles with a fixed capacity of 1000 mA h g at -40 °C. This work paves the way for designing novel electrolytes in low-temperature batteries.