Triple Synergy Unleashed: Bimetallic‐Carbon Nanotube Enabled Near‐Zero‐Strain Prussian Blue Cathodes for High‐Performance Sodium‐Ion Batteries

Abstract Prussian blue analogs (PBAs) are promising sodium‐ion battery (SIBs) cathodes but face practical limitations, including low crystallinity, lattice strain accumulation, and sluggish ion/electron transport. These challenges are overcome through an in situ bimetallic (FeNi)‐encapsulated N‐doped carbon nanotube (FeNi@NCT) precursor strategy to synthesize FeNiPBA/NCT. This approach achieves synergistic “crystallinity‐strain‐transport” optimization: 1) Controlled Fe 2+ /Ni 2+ leaching from precursors promotes high crystallinity; 2) Ni doping weakens framework–Na + interactions and mitigates lattice strain during solid‐solution cycling; 3) An interconnected N‐doped carbon nanotube (NCT) network enhances charge transfer kinetics. Consequently, FeNiPBA/NCT delivers superior rate performance and remarkable cycling stability (83.5% capacity retention after 2000 cycles at 1.0 A g −1 ), demonstrating a scalable paradigm for high‐performance SIB cathodes.