Oxidation-Resistant Cyclic Ether-Based Electrolyte for Sustainable 4.5 V Lithium-Ion Batteries with Robust Low-Temperature Reliability

The development of lithium-ion batteries (LIBs) that integrate high-voltage stability with ultra-low-temperature operational capability remains a critical bottleneck for industrializing next-generation energy storage technologies. Conventional electrolytes cannot simultaneously ensure interfacial stability at high-voltage and efficient ion transport at ultra-low-temperatures due to inherent limitations in their molecular structures. In this study, tetrahydropyran (THP) is employed as the main solvent, capitalizing on its low viscosity and weak solvation ability to optimize low-temperature ion transport kinetics. Meanwhile, fluoroethylene carbonate (FEC) and LiTFSI are introduced as functional additives, which undergo selective redox reactions on the surfaces of the cathode and anode. This enables the directional construction of compositionally uniform and structurally dense CEI and SEI, thereby synergistically suppressing interfacial degradation of high-voltage cathodes and solvent co-intercalation into graphite anodes. Based on this strategy, the formulated THP−FEC (5%) electrolyte allows an NCM811||Gr full-cell to retain 80% of its capacity after 300 cycles at 4.5 V while also delivering 90 mAh·g−1 at −50 °C. Furthermore, a 1 Ah pouch cell using this electrolyte maintains 0.96 Ah after 170 cycles at 25 °C and provides 0.6 Ah when transferred to −20 °C after cycling. This work presents a universal strategy for designing high-voltage and ultra-low-temperature LIB electrolytes through precise component modulation.