An Ultrafast and Stable Li‐Metal Battery Cycled at −40 °C

Abstract Li‐metal battery (LMB) suffers from the unexpected Li dendrite growth and unstable solid‐electrolyte interphase (SEI), especially in extreme conditions, such as high rates low temperatures (LT). Herein, a high‐rate stable LT LMB is realized by regulating electrolyte chemistry. A weak + ‐solvating solvent 2‐methyltetrahydrofuran used to mitigate kinetic barrier for de‐solvation. Moreover, co‐solvent tetrahydrofuran with donor number incorporated improve solubility of salts, achieving an improved ionic conductivity while maintaining ‐solvation effect. Furthermore, abundant FSI ‐ anions contact‐ion pairs are presented, facilitating formation LiF‐enriched SEI. Consequently, Li||Li can be operated at 10 mA cm ‐2 small polarization 154 mV −40 °C. Meanwhile, outstanding cumulative cycling capacity 4000 mAh 8.0 achieved, reaching record level alkali metal symmetric batteries. Also, rechargeable full batteries achieved This work demonstrates superiority chemistry synergistic regulation both ion transfer kinetics SEI toward ultrafast LMBs LT.