Vacancy Remediation in Prussian Blue Analogs for High‐Performance Sodium and Potassium Ion Batteries

Abstract Sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) have enormous potential for large‐scale energy storage due to their cost‐effectiveness, safety, and environmental compatibility. Developing high‐capacity and highly reliable cathode materials is key to advancing the commercialization of SIBs and PIBs. Low‐cost Prussian blue analogs (PBAs), with their open 3D framework and ease of synthesis, are preferred cathode materials for energy storage applications. However, the unique growth mechanism of PBAs introduces numerous Fe(CN)₆ vacancies, which compromise structural integrity and result in capacity decay due to structural collapse during long‐term electrochemical cycling. Additionally, cracking can cause the dissolution of transition metal (TM) ions, undesirable interfacial reactions, and gas generation, which shorten the battery's lifespan and raise safety concerns. In this review, the mechanisms of growth and vacancy formation in PBAs is first clarified, providing a comprehensive overview of current strategies for vacancy remediation based on both bottom‐up and top‐down approaches. It is then elucidate how optimized vacancy remediation mechanisms can enhance lattice and interfacial stability, suppress TM dissolution and mitigate gas generation. Finally, it is discussed future research directions and provide perspectives on the further development of high‐performance cathode materials for SIBs and PIBs.