Electrolyte and Interphase Chemistry for 4.6-V Lithium Metal Batteries Operated below −30 °C

High-voltage lithium metal batteries based on high-nickel layered oxide cathodes are attractive due to their high energy density. However, they suffer from a severe decline in capacity at low temperatures, and the limited voltage range of low-temperature electrolytes fails to meet their application. To address this issue, we developed low-temperature carbonated electrolytes for lithium metal batteries with robust LiP_xO_yF_z- and LiF-rich Li⁺-conductive electrode–electrolyte interphases. The dual interphases with a LiPO₂F₂ additive could accelerate Li⁺ migration, reduce impedance, prevent electrolyte consumption, alleviate cathode degradation, and even mitigate the severe polarization of the Li anode at −50 °C. As a result, a 4.6-V Li||NCM811 cell with an optimized electrolyte sustained 160 cycles before reaching the 80% threshold and sustained a 92% capacity retention rate (139.9 mAh g⁻¹) at 20 mA g⁻¹/−30 °C after 50 cycles. Moreover, it could deliver 118 mAh g⁻¹ even at 20 mA g⁻¹/−50 °C.