The generic formula of PBAs for SIBs could be represented as Na 2−xM 1−y□y These advantages make PBAs quite likely to be mass produced and widely used as low-cost cathodes material for SIBs in the future 11. Compared with other cathodes, the high-temperature calcination is not required during synthesis of PBAs, which effectively lower the manufacturing costs 8. Different cathode materials for SIBs include layered oxides 4, 5, polyanionic compounds 6, 7, and Prussian blue analogs (PBAs) 8, 9, among them, PBAs have attracted tremendous attentions because their open framework structure could easily accommodate Na + and enable its fast transportation 10. Owing to the low-cost and natural abundance of sodium, sodium-ion batteries (SIBs) are considered as an alternative to lithium-ion batteries, which is expected to be utilized for gird-scale energy storage in the future 1, 2, 3. We believe that this work could pave the way for the real application of Prussian blue materials in sodium-ion batteries. Moreover, the Prussian blue material from a large-scale synthesis process shows stable cycling performance in a pouch full cell over 1000 times. The phase transitions in the as-obtained material are investigated by synchrotron in situ powder X-ray diffraction, which shows highly reversible structural transformations between rhombohedral, cubic, and tetragonal structures upon sodium-ion (de)intercalations. Characterization of the nucleation and evolution processes of the highly crystalline Prussian blue microcubes reveals a rhombohedral structure that exhibits high initial Coulombic efficiency, excellent rate performance, and cycling properties.

Here we report a controllable precipitation method to synthesize high-performance Prussian blue for sodium-ion storage. Their materials quality and electrochemical performance are heavily reliant on the precipitation process. Iron-based Prussian blue analogs are promising low-cost and easily prepared cathode materials for sodium-ion batteries.

Naclo4 xps peak sodium ion