High‐Entropy Prussian Blue Analogues Enable Lattice Respiration for Ultrastable Aqueous Aluminum‐Ion Batteries

Abstract Aqueous aluminum ion batteries (AAIBs) hold significant potential for grid‐scale energy storage owing to their intrinsic safety, high theoretical capacity, and abundance of aluminum. However, the strong electrostatic interactions and delayed charge compensation between high‐charge‐density aluminum ions and the fixed lattice in conventional cathodes impede the development of high‐performance AAIBs. To address this issue, this work introduces, for the first time, high‐entropy Prussian blue analogs (HEPBAs) as cathodes in AAIBs with unique lattice tolerance and efficient multipath electron transfer. Benefiting from the intrinsic long‐range disorder and robust lattice strain field, HEPBAs enable the manifestation of the lattice respiration effect and minimize lattice volume changes, thereby achieving one of the best long‐term stabilities (91.2% capacity retention after 10 000 cycles at 5.0 A g −1 ) in AAIBs. Additionally, the interaction between the diverse metal atoms generates a broadened d ‐band and reduced degeneracy compared with conventional Prussian blue and its analogs (PBAs), which enhances the electron transfer efficiency with one of the best rate performance (79.2 mAh g −1 at 5.0 A g −1 ) in AAIBs. Furthermore, exceptional element selectivity in HEPBAs with unique cocktail effect can facile tune electrochemical behavior. Overall, the newly developed HEPBAs with a high‐entropy effect exhibit promising solutions for advancing AAIBs and multivalent‐ion batteries.