Localized Solvent-Anchored Carboxylate Ester Electrolyte Enables Wide Temperature and Fast Charging Sodium Metal Batteries.

Abstract

Sodium-metal batteries (SMBs) have attracted considerable interest due to their abundant raw material supply and high energy density. Nevertheless, realizing fast charging and long-term cycling stability over a wide temperature range remains a considerable challenge. In this work, we propose a novel strategy that integrates molecular anchoring with weak solvation by modulating the dipole-dipole interactions between methyl propionate (MP) and fluoroethylene carbonate (FEC). This approach effectively stabilizes the free solvent ratio, suppresses the irregular dendrite formation under low-temperature and fast-charging conditions, and minimizes HF generation at elevated temperatures, thereby enhancing electrolyte chemical stability and Na⁺ desolvation kinetics. These synergistic enhancements enable rapid Na⁺ transport and facilitate the formation of a robust interface layer across a broad temperature range. Consequently, Na₃V₂(PO₄)₃||Na cells demonstrate stable operation from -40°C to 70°C and sustain over 10 000 cycles at 80°C, outperforming previous reports on wide-temperature fast-charging systems. Notably, the cells achieve a capacity retention of 98.58% after 1200 cycles at -20°C and 85.93% after 1500 cycles at 60°C. Moreover, pouch cells configured with this electrolyte exhibit superior all-weather adaptability and fast-charging capability. This work offers valuable insights for developing high-performance SMBs operable under broad- temperature conditions.