Low-LUMO Solvation Structure Enabled by Propylene Carbonate for Stable Lithium Metal Batteries at Low-Temperature

Propylene carbonate (PC) is a promising ethylene carbonate (EC) replacement for low-temperature electrolytes due to its low melting point (-48.8°C). However, its tendency to form an unstable, organic-rich solid electrolyte interphase (SEI) on Li anodes severely limits practical application. Multicomponent electrolyte show potential in constructing stable interfaces; however, the contribution of specific solvation structures in multicomponent electrolyte to the interface formation process remains unclear. Herein, a multicomponent electrolyte is designed by introducing LiBF₄/ LiDFOB/ LiNO₃ into methyl acetate (MA)/ PC/ fluoroethylene carbonate (FEC) mixed solvent. The PC with a low donor number (15.1) exhibits weak interactions with Li⁺, which not only facilitates rapid Li⁺ desolvation but also allows more anions into the solvation shell to form anion-rich solvation structures. More importantly, the lowest unoccupied molecular orbital (LUMO) energy is significantly lower when PC replaces EC in the solvation structure, which facilitates the formation of an inorganic-rich SEI. The inorganic-rich SEI possesses high mechanical strength, thereby suppressing Li dendrite growth. Consequently, the cell delivers an initial specific capacity of 145.7 mAh g^-1 with 97.5% capacity retention after 180 cycles at -20°C. This work provides a strategy for advanced electrolyte design to realize practical low-temperature LMBs.