Iron-based Prussian blue analogs are promising low-cost and easily prepared cathode materials for sodium-ion batteries. This paper reports a controllable precipitation method to synthesize high-performance Prussian blue for sodium-ion storage. Characterization reveals a rhombohedral structure exhibiting high initial Coulombic efficiency, excellent rate performance, and cycling properties. Synchrotron in situ powder X-ray diffraction shows highly reversible structural transformations between rhombohedral, cubic, and tetragonal structures upon sodium-ion (de)intercalations. Large-scale synthesis yields a material showing stable cycling performance in a pouch full cell over 1000 cycles, suggesting potential for real-world applications in sodium-ion batteries.
