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

(NH4)(Ni,Co)PO4 center dot 0.67H(2)O (NNCP) was successfully synthesized by a simple one-step low-temperature hydrothermal method, and modified by metal oxides CuO, MnO2 and Co3O4, 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/MnO2 and NNCP/Co3O4 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/MnO2 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 MnO2. The specific capacitances of NNCP/MnO2 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.