Entropy-Production Type Prussian Blue Analogues: A Family of Promising Hosts for High-Performance Multivalent-Ion...

The advancement of high-performance, safe, and cost-effective multivalent-ion batteries is pivotal for sustainable energy storage. Prussian blue analogs (PBAs), with their open framework and tunable redox-active sites, hold significant promise but face challenges in structural instability and sluggish ion diffusion. This review focuses on entropy production PBAs (EP-PBAs) for non-monovalent ion (Zn²⁺, Al³⁺, Mg²⁺, and Ca²⁺) battery systems. Incorporating multiple transition metals into PBAs leverages entropy production effects to stabilize crystal structures, enhance ion diffusion kinetics, and improve cycling stability. Synthesis methods such as coprecipitation, electrochemical deposition, and hydrothermal techniques are compared, with coprecipitation emerging as the most scalable approach. Entropy engineering mitigates lattice distortion, reduces defects, and suppresses phase transitions, enabling EP-PBAs to achieve high specific capacities and long-term stability. Challenges including interfacial instability and synthesis complexity are discussed, alongside future directions in material optimization, electrolyte compatibility, and scalable production. This work highlights the potential of entropy-stabilized PBAs as next-generation cathodes for multivalent-ion batteries, advancing sustainable energy storage technologies.