Active cation-integration high-entropy Prussian blue analogues cathodes for efficient Zn storage

Mn-based Prussian blue analogues(Mn-PBAs),featuring a three-dimensional(3D)metal-organic framework and multiple redox couples,have gained wide interests in Zn-ion batteries(ZIBs).However,owing to the Jahn-Teller distortion and disproportionation reaction of Mn^(3+),these materials suffer from poor electrochemical performances and inferior structural stability.Herein,we prepare a typical high-entropy Prussian blue analogue(HE-PBA)with increased configuration entropy through integrating five transition metal elements of Mn,Co,Ni,Fe and Cu into the nitrogen-coordinated-M-lattice sites.Consequently,the HE-PBA presents enhanced uptake of Zn^(2+)with 80 mAh·g^(−1)compared to those medium-entropy PBAs,low-entropy PBAs and conventional PBAs,which can be assigned to“cocktail”effect of multiple transition metal active redox couples.Furthermore,a phase transition process from monoclinic phase to rhombohedral phase occurs in HE-PBA cathode,resulting in a stable structure of MN6(M=Mn,Co,Fe,Ni,Cu)and ZnN4 co-linked to FeC6 through the cyanide ligands.Additionally,the advantages of entropy-driven stability are also confirmed by the calculated reduction energy and the density of states between HE-PBA and KMn[Fe(CN)6](KMnHCF).This work not only presents a high-performance HE-PBA cathode in ZIBs,but also introduces a novel concept of high entropy benefiting for designing advanced materials.