Moderate Solvation Structure Reconstructs Inorganic-Rich Interphases Toward Low-Temperature for Safer Lithium(-Ion) Batteries

Conventional electrolytes severely limit lithium battery performance at low temperatures due to sluggish ion transport and high desolvation energy barriers. Weakly solvating electrolytes facilitate ion desolvation but suffer from limited salt dissociation, leading to the formation of extensive anion-rich aggregates (AGGs). These AGGs increase viscosity and reduce ion mobility, ultimately causing cell failure at low temperatures (≤ −20 °C). Here, we propose a moderate solvation design strategy by tuning weak lithium–solvent interactions to balance salt dissociation and ion mobility. By enhancing the Li + transference number and reducing the desolvation energy barrier, this strategy facilitates the formation of a thin, robust, and uniform cathode electrolyte interface and a LiF-rich solid electrolyte interphase. Together, these features suppress parasitic reactions at the cathode surface and inhibit lithium dendrite growth, ensuring stable electrode-electrolyte interfaces even under subzero conditions. Furthermore, the designed electrolyte demonstrates flame retardancy and high-voltage tolerance. As a result, the Li||LiNi 0.8 Mn 0.1 Co 0.1 O 2 full-cells demonstrate an impressive capacity retention of 95.7% at 4.5 V under −30 °C over 45 cycles (0.1 C). This design approach provides a promising pathway for the development of safe, high-voltage lithium(-Ion) batteries that can operate reliably in low-temperature conditions.