Prussian Blue Analogues with Entropically Stabilized Coordination Environment for High-Energy and Long-Life Aqueous Potassium-Ion Batteries

Prussian blue analogues (PBAs) are highly promising cathode materials for aqueous potassium-ion batteries (APIBs), but yet their practical application is hindered by insufficient redox-active sites and structural instability. Herein, we report a high-entropy strategy to overcome these critical challenges by strategically incorporating multiple 3d transition metals into the PBA framework. We demonstrate that the high-entropy engineering can induce a synergistic cocktail effect that reduces Fe(CN)64– vacancy concentration and promotes charge disordering, and the entropically stabilized coordination environment facilitates heterogeneous bonding, suppresses redox center dissolution, and mitigates detrimental multiphase transitions. Consequently, the high-entropy PBA delivers a high discharge capacity of 142.4 mAh g–1 at 0.2C and exhibits an exceptional cycle life of 88.2% after 5000 cycles, representing the best-level cathode for APIBs. Furthermore, a high-entropy PBAs-based pouch-type full cell demonstrates a high energy density of 122.1 Wh kg–1 with a remarkable capacity retention of 84.3% at a high rate of 20 C, superior to state-of-the-art aqueous battery technology. Our work highlights the immense potential of high-entropy engineering for designing next-generation cathode materials for high-energy-density and ultralong-cycle-life APIBs.