An Ether‐Based Electrolyte Solvation Strategy for Long‐Term Stability and Ultra‐Low Temperature Li‐Metal Batteries

Abstract Unstable solid electrolyte interface (SEI) and dendrite growth hinder the development of rechargeable lithium‐metal batteries (LMBs) at low temperature (≤−20 °C). In this work, regulating the concentration of Li salt increases the proportion of anions in Li⁺ solvation structure, thereby forming a denser SEI on Li anode. The optimized solvation structure exhibits fast charge transfer kinetics and high‐voltage (dis)charge performance. As a result, Li||Cu cells with modified electrolyte work over 400 h and maintaining an average coulombic efficiency of 98.05%, the Li||LiNi_0.8Co_0.1Mn_0.1O₂ cells (N/P = 3) are capable of one hundred stable cycles with a capacity retention of 93.7% even at −40 °C. These findings confirm the effect of ion‐pairing and anion‐derived SEI on the long‐term cycling of LMBs, contributing a promising solution to the development of low‐temperature LMBs.