Anion Coordination Regulation with LiNO3 Additive for High-Rate Low-Temperature Lithium Metal Batteries.

Abstract

Low-temperature environments significantly affect the performance of lithium metal batteries, primarily due to the freezing of commercial electrolytes that induced increased energy barriers for lithium-ion migration and desolvation, unstable solid electrolyte interphases (SEI), and lithium dendrite growth. In this work, an electrolyte was developed with lithium nitrate as an additive and lithium bis(trifluoromethanesulfonyl)imide and lithium hexafluorophosphate as the main lithium salts. Li+-NO3- coordination weakens Li+-solvent binding, enabling anion penetration into solvation shells. This multianion-dominated structure promotes Li+ diffusion/desolvation kinetics while enabling inorganic-rich SEI formation and homogeneous Li deposition. Consequently, Li||Li cells exhibit exceptional stability across -30 to 25 °C with over 2000 h cycle life. Li||NCM811 cells demonstrate outstanding rate capability at 25 °C, retaining 94.7% capacity at 2 C and 85.1% at 5 C over 1000 cycles. Notably, under cryogenic conditions at 0.2 C and -30 °C, the cell achieves 92.4% capacity retention after 400 cycles.