Structural Evolution and Redox Chemistry of Prussian Blue Analogues in Rechargeable Batteries

Prussian blue analogues (PBAs) are one of the most promising classes of cathode materials for next-generation rechargeable batteries due to their tunable crystal structures, multiple redox-active sites, cost-effective synthesis, and ability to accommodate various mobile ions (A = Li, Na, K, etc.). This review provides a comprehensive overview of the fundamental structure-property-performance relationships of PBAs, with particular emphasis on structural evolution and redox chemistry during electrochemical cycling. We detail the redox sequence, lattice volume changes, and phase transition pathways in representative systems of A x P[R(CN)6] where P = Fe, Co, Mn, or Ni and R = Fe, Mn, or Cr. The discussion further addresses the impact of crystal defects (e.g., crystal water and vacancies) and spin-state transitions on the electrochemical performance of PBAs, offering mechanistic insights into their advantages and limitations. Finally, we outline future research directions and application prospects for PBAs, presenting this work as a roadmap for the rational design of high-performance PBA-based electrode materials.