Nanostructured MnO2 Doped with Ni Prepared by Sonochemical Method as Active Material for Electrochemical Capacitor

In many transition metal oxides, the charge storage mechanism is primarily based on pseudocapacitance. Due to their low cost, low toxicity and environmentally friendly character, MnO2 materials are very promising candidates as electrode material in electrochemical capacitors [1]. Most of the efforts aimed at the synthesis of so-called amorphous materials (a-MnO2) due to their large surface area and high capacitance, while crystallized MnO2 material have been less extensively studied. In this work, we have employed a sonochemical method to synthesis γ-MnO2 with addition of Ni to improve the electrochemical properties of MnO2. The MnO2 samples were doped with Ni by sonochemical method from an aqueous solution of potassium bromate and manganese sulfate and addition of Nickel sulfate solution at different ratios of Ni to Mn and different reaction stages. The electrochemical properties of samples were examined using cyclic voltammetry, chronopotentiometry and impedance spectroscopy in 0.5 M aqueous K2SO4 solution at pH=3.