Anionic Solvation Transition\nat Low Temperatures for\nReversible Anodes in Lithium–Oxygen Batteries

Li–O<sub>2</sub> batteries provide a novel technology\nfor\nelectric energy storage due to their high energy density. However,\nthe strong solvent coordination with Li<sup>+</sup> at low temperatures\nimpacts their performance and triggers irreversible interfacial reactions\non the Li anode. Herein, cyclopentyl methyl ether (CME) is incorporated\nin a dimethoxyethane (DME)-based electrolyte to realize an anionic\nsolvation transition at low temperatures in Li–O<sub>2</sub> batteries. CME featuring a single O coordination site substitutes\nhighly solvating DME in the first solvation sheath, and it induces\nmore anion coordination to Li<sup>+</sup> across the room- and low-temperature\nranges. The low residence time of CME (66 ps at 25 °C, 382 ps\nat −40 °C.) in the solvation structures leads to the fast\nexchange of coordinated CME molecules with Li<sup>+</sup> in comparison\nwith DME and facilitates Li<sup>+</sup> desolvation at low temperatures.\nThe simultaneously generated inorganic-rich solid electrolyte interphase\npromotes Li<sup>+</sup> transport to improve Li deposition and suppress\nLi dendrite formation. These enable the Li–O<sub>2</sub> battery\nto present a good cycling stability of 110 cycles with a fixed capacity\nof 1000 mA h g<sup>–1</sup> at −40 °C. This work\npaves the way for designing novel electrolytes in low-temperature\nbatteries.