Scalable Preparation and Electrochemical Sodium-Storage Performance of Fe-Based Prussian Blue Cathode Material

Fe-based Prussian blue material (FePB) was synthesized by coprecipitation method at room temperature using sodium citrate as chelating agent. A high yield of 500 g per preparation can be obtained by using a 20 L reactor and a Na4Fe(CN)(6) precursor with a concentration up to 0.5 mol.L-1. The results of electrochemical measurements indicate that the obtained FePB showed a high capacity, excellent rate capability and long cycle life. At 0.1C, the first discharge capacity of FePB reached 117 mAh.g(-1). At a current density as high as 10C, the FePB can still yield a discharge capacity of 92 mAh.g(-1). After 500 cycles at 1C, a specific capacity of 87 mAh.g(-1) still maintained with a retention of 89%. Pouch-type Na-ion full battery was fabricated using commercial hard carbon as anode and FePB as cathode, which exhibited a capacity retention of 75% after 400 cycles at 50 mA. The excellent electrochemical performance of the FePB is attributed to its high sodium content, low defect, border-rich microstructure and the unique open framework structure of the Prussian blue analogues.