Hierarchical CoP@NiMn-P Nanocomposites Grown on Carbon Cloth for High-Performance Supercapacitor Electrodes

Transition metal phosphides (TMPs) are potential candidates for supercapacitors. To improve their performance by adjusting their morphology and composition, hierarchical CoP@NiMn-P nanocomposites were successfully prepared by the hydrothermal method, electrodeposition, and low-temperature phosphorization. NiMn-P nanosheets were coated on CoP nanowires to form a hierarchical structure. Electrochemical analysis results indicated that the specific capacitance reached 2162.2 F g-1 at 1 A g-1 with a high capacitance retention ratio of 83.3% after 5000 cycles at a current density of 10 A g-1. This excellent electrochemical performance was attributed to the large specific surface area and enhanced conductivity. Furthermore, an asymmetric supercapacitor, CoP@NiMn-P//AC, was prepared using CoP@NiMn-P as the positive electrode and AC as the negative electrode. A large voltage window of 1.6 V and high energy density of 21.1 Wh kg-1 at 804.3 W kg-1 with a good capacity retention rate were achieved. The results confirm that CoP@NiMn-P has good potential for application in high-performance energy storage devices and provide a reference for the design of phosphide with morphology/composition optimization.