Tuning the Electrolyte and Interphasial Chemistry for All‐Climate Sodium‐ion Batteries

Abstract Sodium‐ion batteries (SIBs) present a promising avenue for next‐generation grid‐scale energy storage. However, realizing all‐climate SIBs operating across a wide temperature range remains a challenge due to the poor electrolyte conductivity and instable electrode interphases at extreme temperatures. Here, we propose a comprehensively balanced electrolyte by pairing carbonates with a low‐freezing‐point and low‐polarity ethyl propionate solvent which enhances ion diffusion and Na + ‐desolvation kinetics at sub‐zero temperatures. Furthermore, the electrolyte leverages a combinatorial borate‐ and nitrile‐based additive strategy to facilitate uniform and inorganic‐rich electrode interphases, ensuring excellent rate performance and cycle stability over a wide temperature range from −45 °C to 60 °C. Notably, the Na||sodium vanadyl phosphate cell delivers a remarkable capacity of 105 mAh g −1 with a high rate of 2 C at −25 °C. In addition, the cells exhibit excellent cycling stability over a wide temperature range, maintaining a high capacity retention of 84.7 % over 3,000 cycles at 60 °C and of 95.1 % at −25 °C over 500 cycles. The full cell also exhibits impressive cycling performance over a wide temperature range. This study highlights the critical role of electrolyte and interphase engineering for enabling SIBs that function optimally under diverse and extreme climatic environments.