Dual-Reinforced Solvent Enabling High-Voltage and Wide-Temperature Electrolyte for Lithium Metal Batteries

Lithium metal batteries (LMBs) have attracted extensive attention, owing to their high energy density. However, commercial carboxylate ester-based electrolytes exhibit inadequate oxidation stability and poor compatibility with lithium metal anodes, which restrict the performance of LMBs under high-voltage and wide-temperature conditions. In this work, a dual-reinforced Li⁺ solvation structure is proposed, consisting of 2-ethoxyethyl acetate and sulfolane with lithium hexafluorophosphate and lithium nitrate. The weak solvation capability and low freezing point of 2-ethoxyethyl acetate contribute to a substantial reduction in the Li⁺ desolvation energy. Meanwhile, the lithium nitrate is employed to construct a high durable inorganic-rich solid-electrolyte interphase (SEI) with low impedance. As a result, LMBs comprising a high voltage LiCoO₂ cathode and the optimized electrolyte achieve an excellent capacity retention of 93.3% after 50 cycles at 0.1 C, 4.5 V, and 50 °C. In addition, the electrochemical performance at low-temperature is significantly improved, demonstrating 62.5% capacity retention after 90 cycles at 0.1 C, 4.5 V, and -60 °C. This work presents an approach for the development of electrolytes for high-voltage and wide-temperature LMBs.