Effect of Ni-doping on electrochemical capacitance of MnO₂ electrode materials

Abstract

Mn/Ni composite oxides as active electrode materials for supercapacitors were prepared by solid-state reaction through the reduction of KMnO₄ with manganese acetate and nickel acetate at low temperature. The products were characterized by X-ray diffractometry(XRD) and transmission electron microscopy(TEM). The electrochemical characterizations were performed by cyclic voltammetry (CV) and constant current charge-discharge in a three-electrode system. The effects of different potential windows, scan rates, and cycle numbers on the capacitance behavior of Mn_0.8Ni_0.2O_x composite oxide were also investigated. The results show that the composite oxides are of nano-size and amorphous structure. With increasing the molar ratio of Ni, the specific capacitance goes through a maximum at molar fraction of Ni of 20%. The specific capacitance of Mn_0.8Ni_0.2O_x composite oxide is 194.5 F/g at constant current discharge of 5 mA.

Keywords

MnO₂ / supercapacitor / capacitance / Ni doping / composite oxide

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