Thermoresponsive ether-based electrolyte for wide temperature operating lithium metal batteries

Safe electrolytes operable over a wide temperature range are essential for lithium metal batteries, offering high redox interfacial stability, fast ion transport kinetics, and inherent safety. However, conventional electrolytes rarely achieve these characteristics simultaneously, typically sacrificing one to improve another. In this work, an ether-based thermoresponsive electrolyte is developed, in which the Li+ solvation structure varies with temperature and facilitates the formation of a polycrystalline electrode/electrolyte interface, enabling the desired properties under conventional salt concentrations. The solvation sheath is reconfigured by 1,3,5-trioxane, which promotes anion dissociation and enhances charge-transfer kinetics. Additionally, 1,3,5-trioxane triggers a cationic ring-opening polymerization of tetrahydrofuran at 60 °C, yielding oxidation-resistant ether-based polymers that improve high-temperature stability and safety. As a result, Li||LiNi0.8Co0.1Mn0.1O2 cells utilizing this electrolyte operate reliably across a broad temperature window (−60 to 60 °C). Furthermore, a practical 1.5 Ah Li|| Ni0.8Co0.1Mn0.1O2 pouch cell delivers a capacity retention of 74.7% after 60 cycles at −40 °C and 0.05 C (20 h charge/discharge), with a specific energy of 317.1 Wh kg−1(including packaging foil).