Breaking Aggregation State to Achieve Low‐Temperature Fast Charging of Lithium Metal Batteries

Insufficient ionic conductivity and elevated desolvation energy barrier of electrolytes limit the lithium metal batteries (LMBs) low‐temperature applications. Weakly solvating electrolytes (WSEs), with limited lithium salt dissociation capability, are prone to desolvate and drive anion‐rich aggregates (AGGs). However, significant AGGs result in increased viscosity and low ionic mobility, contributing to battery failure at low temperatures (≤ −20 oC). Here, we propose and achieve a transformation of solvation structures from AGGs to contact ion pairs (CIPs) through modulating the overall solvation capability, thereby achieving the balance between weak Li+ ‐ solvent interactions and desired ion migration kinetics. Remarkly, CIPs‐dominated electrolyte shows a ten‐fold increase in ionic conductivity compared to conventional WSEs. The Li||LiFePO4 (LFP) battery achieves more than 1400 cycles with 86.9% capacity retention at 5 C. The practical 1.2 Ah LFP pouch cell delivered 69% of the capacity at 25 oC when cycled at −40 oC. This strategy for solvation structure transformation in WSEs provides a novel approach for the development of electrolytes for low‐temperature batteries.