Metal oxide modified (NH4)(Ni,Co)PO4·0.67H2O composite as high-performance electrode materials for supercapacitors

(NH 4 )(Ni,Co)PO 4 ·0.67H 2 O (NNCP) was successfully synthesized by a simple one-step low-temperature hydrothermal method , and modified by metal oxides CuO , MnO 2 and Co 3 O 4 , so that the composites with different length scales and different energy storage mechanisms could be synergistically integrated. The electrochemical behaviors of NNCP, NNCP/CuO, NNCP/MnO 2 and NNCP/Co 3 O 4 as supercapacitor electrode materials in 3 mol·L −1 KOH electrolyte were studied by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS), and the morphology and structure of the synthesized materials were studied by SEM, XRD and Raman spectrum . Compared with other samples, the optimized NNCP/MnO 2 composites have higher specific capacitance and remarkable rate capability due to the micron flower-like rich interface structure , which provides a more active sites for electrochemical reaction , a shorter transport path for electrolyte ions, and the synergistic effect of NNCP and MnO 2 . The specific capacitances of NNCP/MnO 2 at current densities of 1, 4, 7 and 10 A g −1 are 3626, 3336, 3140 and 3104 F g −1 , respectively. These excellent properties confirm that the composite material has broad application prospects in the field of supercapacitor materials .