Fe-substituted Mn-based Prussian white as cathode for high-performance potassium-ion battery

Prussian white (PW) has a stable three-dimensional frame structure and large ion migration channels, which has been widely studied as the cathode materials for potassium-ion batteries (PIB) in recent years. The multi-composition in PWs has a great impact on the electrochemical performance as cathode materials. In this work, we investigated the relationship between Fe substitution content and electrochemical properties. The sample of PW with 10%Fe substitution shows the overall optimum electrochemical performance, which delivers a high reversible capacity of 124.3 mAh g−1 and capacity retention of 70.0% after 200 cycles at 100 mA g−1, as well as 77.5 mAh g−1 at a large current density of 500 mA g−1. Actually, partial Fe substitution could effectively stabilize the lattice structure and improve electrochemical properties. This work provides a practical strategy to synthesize PWs with stable crystal structure and preferable performance, which could serve as a reference for the electrochemical improvement of electrode materials.Graphical Abstract