Prussian Blue Nanoplates for Potassium Ion Battery Cathode with High Capacity and High Energy Density

Prussian blue analogues represent as a class of materials with an open framework structure and have been explored as the potential active materials for alkaline‐ion batteries. Here, we present the synthesis of Prussian blue nanoplates (PBN) designed for use as high performance cathode materials in potassium‐ion batteries (KIBs). PBNs were synthesized through a facile solution precipitation, yielding potassium‐rich PBNs with horizontal crystals growth. The PBNs characterized with a larger particle size of 600 nm and a reduced specific surface area of 6.8 m2 g‐1, compared to conventional prepare Prussian blue hexahedrons. Half‐cell tests demonstrated that the PBNs exhibited a high gravimetric capacity of 152.5 mAh g‐1 with a nominal voltage 3.952 V at a C‐rate of 0.1 C, yielding an energy density of 602.7 Wh kg‐1. Cycling tests demonstrated a capacity of 122.7 mAh g‐1 and a nominal voltage of 3.923 V after 200 cycles at 0.2 C. In a full‐cell configuration with graphite anodes, a gravimetric capacity changed from 134.1 mAh g‐1 to 108.9 mAh g‐1 after 100 cycles at 0.2 C, demonstrating a good cycling stability. This work provides a new insight into the electrochemical properties of PBNs and highlights their potential as high‐performing cathode materials for KIBs.