Rapid and Recyclable Synthesis of Prussian Blue Analogs by Enrichment Crystallization Strategy for Wide-Temperature Sodium-Ion Cylindrical Cells.

Manganese hexacyanoferrate (MnHCF) exhibits a high operating voltage, making it a promising candidate as a cathode material for sodium-ion batteries (SIBs) with high energy density. However, the conventional slow co-precipitation method suffers from the drawback of being time-consuming, hindering its scalability for practical applications. Although rapid co-precipitation strategies can address the above issue and enhance production efficiency, they often lead to uncontrolled crystal growth, resulting in increased vacancy content and lattice water that degrade sodium-ion storage reversibility and electronic conductivity. Herein, a recyclable high-stoichiometric enrichment crystallization strategy is introduced to precisely regulate nucleation kinetics under rapid synthesis conditions. This approach effectively suppresses the formation of vacancies and the introduction of lattice water, while also enabling the efficient recycling of precursor solution to save cost. As a result, the synthesized low-defect MnHCF (MHCF-R) exhibits higher electronic conductivity and enhanced reversible capacity across a broad temperature window (-40°C to 55°C). Notably, 800 mAh-level 18650-type cylindrical cells assembled with MHCF-R electrodes deliver excellent cycling stability, retaining 81.23% of their initial capacity after 500 cycles. This work offers valuable insights into the fast construction of high-conductivity, high-capacity, and wide-temperature-tolerant Prussian blue analogs for SIBs.