Soft-templating and hydrothermal synthesis of NiCo2O4 nanomaterials on Ni foam for high-performance supercapacitors

Nickel cobalt oxide (NiCo2O4) was successfully grown on the nickel foam by a mild hydrothermal method combined with a simple annealing treatment, utilizing SDS, PVP, CTAB, and PVA as template agents. The effect of different template agents on the morphology and electrochemical performance of NiCo2O4 electrode for supercapacitor was further investigated in detail. The physicochemical properties of the NiCo2O4 materials were examined via the X-ray diffraction and the scanning electron microscopy. It could be seen from the XRD patterns that there were no other clear clutter peaks, which indicated that the purity of the material was relatively high. As shown by the SEM diagram, the prepared NiCo2O4 showed different morphology structures via the addition of the template agent, whichexhibited high capacitance and cycling stability. Specially, the NiCo2O4 electrode with the usage of 0.75g SDS, PVP, CTAB, PVA, and none template agents showed high capacitance of 1357, 1469, 1290.6, 1297.4, and 863.8Fg(-1) at 1Ag(-1). In addition, asymmetric supercapacitors (ASC) were assembled with the brilliant binary oxides as the positive electrode, activated carbon as negative electrode, and 6mol/L KOH solution as electrolyte. The ASC device demonstrated a high energy density of 64.76Whkg(-1) at a power density of 774.8Wkg(-1). Remarkably, it still displayed desirable cycle retention of 84.39% over 5000cycle numbers at a current density of 10Ag(-1), and the excellent electrochemical performance suggested its potential application in electrode material for supercapacitor.