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

Prussian blue analogues (PBAs) represent as a class of materials with an open framework structure and have been intensively explored as the potential active materials for alkaline-ion batteries. Here, we present the synthesis of Prussian blue nanoplates designed for use as high performance cathode materials in potassium-ion batteries. Prussian blue nanoplates were synthesized through a facile solution precipitation route using a highly concentrated potassium citrate solution. The potassium-rich environment during the synthesis facilitated horizontal growth of the crystals, yielding potassium-rich Prussian blue nanoplates. The resultant Prussian blue nanoplates exhibited a significantly larger particle size of 600 nm and a reduced specific surface area of 6.8 m2 g-1, compared to conventionally synthesized Prussian blue hexahedrons. Half-cell tests demonstrated that the Prussian blue nanoplates 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 high cycling stability of the material, maintaining 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 Prussian blue nanoplates and highlights their potential as high-performance cathode materials for potassium-ion batteries. Synopsis Prussian blue analogues formed with plates-like nanoparticles were produced via simple precipitation in high concentrated potassium citrate solution and utilized as cathode materials for high capacitive potassium ion batteries with high nominal voltage. image