Scale-up Preparation of Na-Enriched Prussian White\nCathode Assisted by Manganese Oxalate for Sodium-Ion Batteries

Sodium\nmanganese hexacyanoferrate, also called Prussian white (PW),\nhas attracted much attention as a promising cathode material for Na-ion\nbatteries due to its high-voltage platform and inexpensive elemental\ncomposition. However, their parasitic vacancies and water molecules\noften deteriorate the electrochemical performance. Proper regulation\nof such defects in scale-up preparation is still a challenge. In this\nwork, PW was prepared via aqueous precipitation assisted by manganese\noxalate in a 10 L reactor. High-quality Na<sub>2.32</sub>Mn[Fe(CN)<sub>6</sub>]<sub>0.95</sub>□<sub>0.05</sub>·1.97 H<sub>2</sub>O was obtained and exhibited a specific capacity of 148 mAh g<sup>–1</sup>. The phase transition from monoclinic to rhombohedral\nduring long-term cycling for such an ultra-Na-rich cathode has been\nfirst reported. In addition, the vacuum drying temperature was further\ndiscussed, and 150 °C is more suitable for achieving the balance\nbetween dehydration and electrical properties.