Synthesis of Iron-Based Prussian Blue Analogues with Ultralong Cycle Performance in a Novel T-Shaped Collision Microreactor.

Iron based Prussian blue analogues (Fe-PBA) hold significant promise cathode materials for sodium ion batteries due to their low cost and desirable electrochemical properties. However, their practical application is often hindered by the presence of vacancy defects and issues of oxidation that arise during the material preparation process. To overcome these challenges, this study introduces an innovative T-shaped collision microreactor aimed at promoting a uniform concentration field, narrowing the gap between material mixing rate and reaction rate, and providing an oxygen-free environment for the synthesis of Fe-PBA. Employing this microreactor, Fe-PBAs were synthesized with a meticulous approach that led to a material possessing a well-defined morphology and a stoichiometry of Na _1.54 Fe[Fe(CN) ₆ ] _0.93 . The material exhibited a notable reduction in vacancy defects and minimized oxidation levels. Upon electrochemical evaluation, the Fe-PBA crafted within the microreactor demonstrated an impressive specific capacity of 94.1 mAh/g at a current density of 0.5 C and showcased a long-term cyclability with 72.6% capacity retention over 2000 cycles. Comparative analysis revealed that the structural and electrochemical properties of Fe-PBA prepared in the microreactor outperformed those of samples prepared using traditional reactors. This work provides a new approach for the continuous and stable fabrication of high-performance battery cathode materials.