Preparation and characterization of nanostructured NiO/MnO2 composite electrode for electrochemical supercapacitors

Nanostructured nickel-manganese oxides composite was prepared by the sol-gel and the chemistry deposition combination new route. The surface morphology and structure of the composite were characterized by scanning electron microscope and X-ray diffraction. The as-synthesized NiO/MnO2 samples exhibit higher surface area of 130-190 m2 g-1. Cyclic voltammetry and galvanostatic charge/discharge measurements were applied to investigate the electrochemical performance of the composite electrodes with different ratios of NiO/MnO2. When the mass ratio of MnO2 and NiO in composite material is 80:20, the specific capacitance value of NiO/MnO2 calculated from the cyclic voltammetry curves is 453 F g-1, for pure NiO and MnO2 are 209, 330 F g-1 in 6 mol L-1 KOH electrolyte and at scan rate of 10 mV s-1, respectively. The specific capacitance of NiO/MnO2 electrode is much larger than that of each pristine component. Moreover, the composite electrodes showed high power density and stable electrochemical properties