Dual‐Anion Solvation Chemistry for High‐Temperature Sodium‐Ion Full Batteries

Abstract Sodium‐ion batteries with exceptional high‐temperature tolerance are regarded as highly promising energy storage technology for extreme high‐temperature climates. However, the dissolution of the electrode‐electrolyte interface (EEI) at high operating temperatures severely compromises its stability, leading to rapid degradation of sodium storage performance. Herein, a dual‐anion solvation chemistry is constructed by combining the FSI − and ClO 4 − anion to boost the high‐temperature performance of SIBs. The unique anion‐reinforced solvation structure fosters the formation of thin, insoluble inorganic‐rich EEI. The successive decomposition and transition metal dissolution at extreme temperatures are effectively inhibited by the robust EEI. Therefore, the pouch cell composed of Prussian blue cathode and hard carbon anode with high mass loading delivers high Coulombic efficiency and excellent cycle stability at elevated temperatures, with high‐capacity retention of 83.7% after 500 cycles. This study provides valuable guidance for the application of dual‐salt electrolytes in high‐temperature sodium‐ion full batteries.