Nanostructured Mn–Cu binary oxides for supercapacitor

•Nanostructured Mn-Cu-O oxides (MCO) were obtained at the temperature of 550 ˚C.•MCO with 10% mol Cu content possess the maximum specific capacitance of 422 F g-1.•The MCO electrodes show high power density. Nanostructured Mn–Cu binary oxides (MCO) were prepared by thermal decomposition of the precursor obtained by ball milling of Mn and Cu salts. Tailoring the material characteristics and thus the electrochemical performance of the oxide is attempted by component changing (Cu content from 0mol% to 50mol%). The crystal structure and surface morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Cyclic voltammetry, impedance and galvanostatic charge–discharge measurements were employed to investigate the electrochemical performance of the composite electrodes. When the molar ratio of Mn and Cu in composite material is 90:10, the specific capacitance of MCO calculated from the cyclic voltammetry curves is 422Fg−1, however, that of pure Mn2O3 is 92Fg−1 in 6M KOH electrolyte and at scan rate of 5mVs−1, respectively. The specific capacitance of MCO electrode is much larger than that of pure Mn2O3. Moreover, the composite electrodes show high power density.