In-situ growth of Co-Ni hydroxide nanosheets on 3D carbon fiber network with enhanced capacitive performance

The Co-Ni LDH/carbon fiber was prepared through a simple hydrothermal method using the cotton as the carbon source, and investigated as electrode materials for use in supercapacitors. The morphology and structure of the resulting samples were analyzed by SEM, and XRD techniques, respectively, and characterization results proved Ni-Co hydroxide nanosheets were orderly grown on the carbon fiber surface with 3D network structure. In comparison to Co-Ni hydroxides grown on the nickel foam substrate, the Co-Ni LDH/carbon fiber electrode displayed the superior specific capacitance of 1600 F/g at 0.5 A/g and excellent cycling stability of 87.9% retention at 10 A/g after 2000 cycles in 2.0 M KOH electrolyte. AC impedance results illustrated that the electron transfer resistance of Co-Ni LDH/carbon fiber electrode was significantly lower than that of the Co-Ni LDH/Ni foam electrode, illustrating that the carbon fiber can effectively promote the dispersion of Co-Ni LDH, decrease the electron transfer resistance of the as-prepared electrode materials, and ultimately improve the energy storage properties of Co-Ni LDH/carbon fiber. Moreover, the highly ordered Co-Ni LDH nanosheets advanced the contact between KOH electrolyte and the active materials on the electrode, thereby developing the capacitive performance of Co-Ni LDH/carbon fiber. The above results obviously demonstrate 3D Co-Ni LDH/carbon fiber serves as an encouraging electrode material for the application of high-performance supercapacitor.