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

Abstract Developing wide-temperature range and safety electrolytes for lithium metal batteries (LMBs) is expected to possess high redox interfacial stability, rapid kinetics and intrinsic safety. However, traditional electrolytes are rarely able to satisfy all of these characteristics simultaneously, often exhibiting preference for one over the other. Herein, we present a novel ether-based thermoresponsive electrolyte, that are designed by temperature-dependent Li+ solvation structure and forming polycrystalline electrode/electrolyte interface, can achieve the above characteristics at conventional salt concentration. The solvation sheath in the novel electrolyte is reconstructed by 1,3,5-trioxane (TO), accelerating the dissociation and charge transfer kinetics of anions. TO also induces cationic-ring-opening polymerization of tetrahydrofuran solvent molecules at 60 oC to produce oxidation-resistant ether-based polymers, which enhances the high-temperature performance and safety of LMBs. Consequently, the Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) cells using this thermoresponsive electrolyte operate well over a wide temperature range (from −60 to 60 oC). Besides, the Li||NCM811 pouch cell (1.5 Ah) achieve a high capacity-retention of 74.7% after 60 cycles at −40 °C, accompanied by an impressive energy density of 317.1 Wh kg−1.