Extending the molecule chain of ether solvent enables high-voltage lithium metal batteries over a wide-temperature-range

The resurgence of lithium metal batteries (LMBs) has opened new avenues for the advancement of high-energy density secondary batteries. However, the electrochemical performance of LMBs at extreme temperatures remains suboptimal. As a critical component, electrolytes significantly influence the wide-temperature performance of LMBs. Designing an electrolyte system with superior characteristics represents a straightforward and effective approach to expanding the operational temperature range of LMBs. Here, based on a molecular structure design perspective, ethylene glycol dibutyl ether (EG) was selected as the solvent from a series of linear ethers to develop a novel localized high-concentration electrolyte (EG-LHCE). As a result, the substantial steric effect induced by butyl groups in EG molecules facilitates the formation of an anion-rich solvation structure. Furthermore, the diluent not only further promotes the rapid de-solvation of Li+ through dipole-dipole interactions with EG, but also co-decomposed with anions to establish an inorganic-rich electrode/electrolyte interface (EEI). Consequently, 4.4 V-class Li||NCM811 cells utilizing EG-LHCE exhibit remarkable stability from-30 to 60 degrees C. Even under the harsh conditions of ultrahigh loading cathode (21.5 mg/cm2) and limited lithium reservoir (N/P = 2), stable operation is maintained (93 %, 150 cycles). This work provides valuable insight into designing electrolytes for wide-temperature LMBs.