The nano-MnO2 as active electrode material for supercapacitor was synthesized by solid-state reaction between KMnO4 and manganese acetate at room temperature. The products annealed at 100℃ and 200℃ were characterized by XRD and TEM. The results showed the sample annealed at 100℃ was poorly crystallized phase with an average grain size of <20 nm. Electrochemical performances of manganese oxide electrode were investigated by cyclic vohammetry and constant current charge/discharge. The manganese oxide electrode annealed at 100℃ in 1 mol.L-1 Na2SO4 aqueous electrolyte exhibited excellent capacitive behavior between -0.2 and +0.8 V (vs SCE). By 5 mA and 10 mA constant current charge/discharge, the nano-MnO2 annealed at 100℃ can provide a specific capacitance of 158.5 F.g-1 and 151.2 F.g-1, respectively.
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