Highly Crystalline Multivariate Prussian Blue Analogs via Equilibrium Chelation Strategy for Stable and Fast Charging Sodium‐Ion Batteries

Abstract Prussian blue analogs (PBAs) have been widely recognized as superior cathode materials for sodium‐ion batteries (SIBs) owing to numerous merits. However, originating from the rapid crystal growth, PBAs still suffer from considerable vacancy defects and interstitial water, making the preparation of long‐cycle‐life PBAs the greatest challenge for its practical application. Herein, a novel equilibrium chelation strategy is first proposed to synthesize a high crystallinity (94.7%) PBAs, which is realized by modulating the chelating potency of strong chelating agents via “acid effect” to achieve a moderate chelating effect, forcefully breaking through the bottleneck of poor cyclic stability for PBAs cathodes. Impressively, the as‐prepared highly crystalline PBAs represent an unprecedented level of electrochemical performance including ultra‐long lifespan (10000 cycles with 86.32% capacity maintenance at 6 A g −1 ), excellent rate capability (82.0 mAh g −1 at 6 A g −1 ). Meanwhile, by pairing with commercial hard carbon, the as‐prepared PBAs‐based SIBs exhibit high energy density (350 Wh kg −1 ) and excellent capacity retention (82.4% after 1500 cycles), highlighting its promising potential for large‐scale energy storage applications.