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

Sodium manganese hexacyanoferrate, also called Prussian white (PW), has attracted much attention as a promising cathode material for Na-ion batteries due to its high-voltage platform and inexpensive elemental composition. However, their parasitic vacancies and water molecules often deteriorate the electrochemical performance. Proper regulation of such defects in scale-up preparation is still a challenge. In this work, PW was prepared via aqueous precipitation assisted by manganese oxalate in a 10 L reactor. High-quality Na_2.32Mn[Fe(CN)₆]_0.95□_0.05·1.97 H₂O was obtained and exhibited a specific capacity of 148 mAh g^-1. The phase transition from monoclinic to rhombohedral during long-term cycling for such an ultra-Na-rich cathode has been first reported. In addition, the vacuum drying temperature was further discussed, and 150 °C is more suitable for achieving the balance between dehydration and electrical properties.