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

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. Ethyl propionate solvent with low‐polarity and low‐freezing‐point enhances ion diffusion and Na+‐desolvation kinetics at sub‐zero temperatures. In addition, the combinatorial borate‐ and nitrile‐based additive strategy 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.