High‐Entropy Prussian Blue Analogues as Cathodes for High‐Performance Aqueous Al‐Ion Batteries

ABSTRACT Prussian blue analogues (PBAs) are promising cathodes for aqueous aluminum‐ion batteries (AAIBs) due to their 3D open frameworks, which potentially facilitate fast Al ³⁺ transportation. However, their practical applications are severely hindered by poor electronic conductivity, suboptimal Al ³⁺ diffusion kinetics, and structural degradation. This study proposes a high‐entropy Prussian blue analogue (HE‐HCF) cathode through synergistic incorporation of multiple transition metals (Mn, Fe, Ni, Cu, and Zn) to enhance aqueous Al ³⁺ storage. This approach alters the local coordination environment, inducing the reduction of [Fe(CN) ₆ ] groups and thus enhancing their reactivity. Moreover, density functional theory (DFT) calculations reveal improved electronic conductivity and decreased Al ³⁺ diffusion barrier. When coupled with a polyvinylidene fluoride‐coated Zn‐Al alloy (Zn‐Al(P)) anode, the assembled HE‐HCF//Zn‐Al(P) full cell delivers a high capacity of 110 mAh g ⁻¹ at 0.1 A g ⁻¹ and a high energy density of 163.8 Wh kg ⁻¹ . Additionally, the full cell achieves a long lifespan of 1600 cycles at 1.0 A g ⁻¹ , which is attributed to the low fluctuation of lattice parameters brought from strengthened metal‐cyanide bonds within HE‐HCF. This work provides new insights into the design of multivalent ion batteries employing high‐entropy engineering.