Recent progress of manganese-based Prussian blue analogue cathode materials for sodium-ion batteries

Prussian blue and its analogues are widely used in the area of energy storage and conversion due to their low cost, simple synthesis, and notable electrochemical performance. Among various types of Prussian blue and its analogues, manganese-based Prussian blue analogues are preferred owing to their exceptional electrochemical performances. In this regard, they have attracted interest as cathode materials for sodium-ion batteries. In this review, the major synthesis techniques for NaxMn[Fe(CN)6]y (MnHCF), including coprecipitation, electrodeposition, ball milling, and hydrothermal methods, are systematically summarized after a short description of the crystal structure and reaction mechanism of MnHCF. Moreover, the main issues of MnHCF and related optimization strategies are presented. Additionally, a specialized part of this review is provided for NaxMnII[MnII(CN)6] (MnHCM), which is an emerging and rarely reported material with high specific capacity (209 mAh g-1). Finally, challenges faced by manganese-based Prussian blue analogues and their potential development are discussed.