Nanostructured Co doped Mn3O4 spinel structure ((Co, Mn)3O4) were prepared by co-precipitation under O3 oxidizing conditions and post-heat treatment. The product was composed of nanogranules with a diameter of 20-60 nm. The electrochemical performance of (Co, Mn)3O4 electrode was tested by cyclic voltammetry, impedance, and galvanostatic charge-discharge measurements. A maximum specific capacitance value of 2701.0 F g-1 at a current density of 5 A g-1 could be obtained within the potential range from 0.01 to 0.55 V versus Hg/HgO electrode in 6 mol L-1 KOH electrolyte. When at high current density of 30 A g-1, the capacitance is 1537.2 F g-1 or 56.9% of the specific capacitance at 5 A g-1, indicating its good rate capability. After 500 cycles at 20 A g-1, the specific capacitance remains 1324 F g-1 with a capacitance retention of 76.4%.
Keywords: Cobalt doping; Manganese oxide; Nanogranules; Ozone; Supercapacitor.