Recent advances in structural and interfacial chemistry of Prussian blue analogues for sodium-ion batteries

Prussian blue analogues (PBAs) have emerged as leading cathode materials for sodium-ion batteries owing to their open framework structure, low cost, and scalable synthesis. While early studies primarily focused on compositional and morphological optimization, recent advances have revealed that structural chemistry and interfacial reactions critically govern electrochemical performance, degradation behavior, and long-term stability. This mini review will highlight recent progress in understanding crystal water, structural evolution, surface degradation mechanisms, and emerging stabilization strategies. Particular attention will be given to the interplay between bulk structural characteristics and interfacial chemistry, which collectively determines the practical performance of PBA cathodes. By integrating these recent developments, we aim to provide a timely perspective on key challenges and future directions for the practical deployment of PBA cathodes in sodium-ion batteries.