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

Abstract

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 LiPxOyFz- 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.