Inhibiting Mn Dissolution of Mn-Based Prussian Blue Analogue Through Cross-Linking Network for Sustainable Sodium-Ion Battery

Mn-based Prussian blue analogue (MnPBA) with high reaction potential and high reversible capacity is regarded as one of the most promising cathode materials for sodium ion batteries (SIBs). However, the catastrophic Mn dissolution leads to the collapse of the MnPBA structure and the rapid capacity decay. In this study, the Mn dissolution is effectively inhibited through a strong cross-linking network between sodium alginate (SA) macromolecules and the Mn ions on the surface of MnPBA. The formed strong coordination bonding [Mn(SA)_n] firmly anchors Mn ions to avoid electrolyte attack, resulting in a nearly sixfold reduction in Mn dissolution. Moreover, this [Mn(SA)_n] cross-linking network can accelerate the charge transfer, thereby improving the electrochemical reaction kinetics of sodium ions. Owing to this unique coordination model, the enhanced Mn-SA electrodes exhibit a high discharge capacity (143.7 mAh g⁻¹) and dramatic improvement in stability (over 1000 cycles). This study opens up a promising avenue for improving the structural stability of a wide range of Mn-based cathode materials in practical battery systems.