A Universal Precipitation-Transformation Strategy Toward Low-Defect Prussian Blue Analogs for High-Performance...

Prussian blue analogs (PBAs) are considered promising cathode materials for sodium-ion batteries (SIBs) due to their low cost and open framework structure. However, their practical application is hindered by intrinsic [Fe(CN)₆]^4- vacancies and coordinated water, which degrade electrochemical performance, alongside challenges in scalable and cost-effective synthesis. Herein, we report a universal precipitation-transformation strategy that utilizes insoluble metal compounds as precursors to synthesize highly crystalline PBAs. This approach leverages the slow dissolution-precipitation equilibrium of low-solubility precursors to precisely control metal ion release, fundamentally retarding nucleation and crystal growth kinetics. The strategy demonstrates excellent versatility, enabling the synthesis of single-metal, binary-metal, multi-metal, and even high-entropy PBAs with monoclinic or cubic structures, and is readily scalable to 596-gram-level production. As a SIB cathode, the optimized Fe-based PBA (T-FeHCF) exhibits a high specific capacity of 150.5 mAh g^-1 at 0.1 C, excellent rate capability (73.6 mAh g^-1 at 20 C), and outstanding cycling stability with 93% capacity retention after 2000 cycles at 5 C. Full-cells assembled with hard carbon anodes further demonstrate practical viability, maintaining over 85% capacity retention after 400 cycles. This cost-effective and environmentally benign synthesis platform provides a viable pathway toward the commercialization of high-performance PBA cathodes for sustainable energy storage.