The nano-MnO2 as active electrode material for supercapacitor was synt hesized by solid-state reaction between KMnO4 and manganese acetate at room temp erature. The products annealed at 100 ℃ and 200 ℃ were characterized by XRD an d TEM. The results showed the sample annealed at 100 ℃ was poorly crystallized phase with an average grain size of <20 nm. Electrochemical performances of mang anese oxide electrode were investigated by cyclic voltammetry and constant curre nt 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, th e nano-MnO2 annealed at 100 ℃ can provide a specific capacitance of 158.5 F·g- 1 and 151.2 F·g-1, respectively.
