Practical and Versatile Sodium‐Ion Batteries Realized With Nitrile‐Based Electrolytes

Abstract Sodium‐ion batteries (SIBs) hold tremendous potential in next‐generation energy storage. However, no SIB has yet achieved simultaneous support for high voltage, rapid charging, and all‐climate adaptability due to electrolyte limitations. This study successfully constructs versatile SIBs using an optimized acetonitrile (AN)‐based electrolyte, which offers excellent high‐voltage tolerance, high ionic conductivity, anion‐enriched solvation structure, and a wide liquidus temperature range. The engineered solid electrolyte interphase (SEI) exhibits low resistance and exceptional stability, effectively supporting fast charging, temperature‐adaptive operation, and long‐term cycling stability. Consequently, this tailored electrolyte, combined with a robust SEI, enables hard carbon (HC) anodes to achieve a high reversible capacity of 223 mAh g −1 at a fast rate of 5 C. When paired with a high‐voltage NaNi 1/3 Fe 1/3 Mn 1/3 O 2 (NFM) cathode, the HC||NFM full cells operate stably at a high cut‐off voltage of 4.15 V, sustaining over 1400 cycles at 5 C. Furthermore, a practical 3 Ah pouch cell demonstrates excellent stability, retaining 90.7% of its capacity after 1000 cycles, and shows all‐climate adaptability, maintaining 56.4% of its room‐temperature capacity at −60 °C and 97.3% retention after 350 cycles at 50 °C. This work provides valuable insights for developing advanced electrolytes for versatile and practical SIBs.