Unveiling the role of mixing in [Fe(CN)6]4− defects and Na content for preparing NaxMn[Fe(CN)6]y · nH2O via microreactor

Taking advantage of strong mixing performance in oscillating feedback microreactor (OFM), the manganese hexacyanoferrates (NaxMn[Fe(CN)6]y · nH2O, MnHCFs) with low defects and high sodium content were controllably prepared. First, fluid mixing performance in OFM was investigated via dye‐tracer and Villermaux‐Dushman experiments, and the fluid mixing mechanism in OFM was investigated through CFD simulations. Then, MnHCFs were prepared using OFM at different flow rates, and the role of mixing in [Fe(CN)6]4− vacancies and sodium content during co‐precipitation synthesis of MnHCFs was discussed. The results indicate that an increase in flow rates can increase fluid chaos strength, enhancing the mass transfer process to match the extremely fast reaction rate of MnHCFs, thus preparing MnHCFs with high sodium content and low defects. Relevant electrochemical tests indicate that the MnHCF prepared at the largest throughput (180 mL/min) has the highest initial specific capacity (132 mAh/g at 15 mA/g), minimum electrochemical impedance, and fastest sodium ion transport rate.