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.
Choi et al. (Fri,) studied this question.