Abstract:

Mn₃O₄ nanoparticles were prepared in alkaline solution and their electrochemical characteristics were investigated. The obtained Mn₃O₄ nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), cyclicvoltammetry (CV), galvanostatic charge/discharge (GC/D), and electrochemical impedance spectroscopy (EIS). The Mn₃O₄ nanoparticles can be prepared directly in NaOH and NH₃ solution. MnCO₃ is only obtained in Na₂CO₃ solution, and can be transformed to Mn₃O₄ nanoparticles in the presence of NaOH. The crystalline sizes of the Mn₃O₄ nanoparticles prepared in NaOH, NH₃ and Na₂CO₃ solution are 29.5 nm, 20.2 nm and 36.3 nm, respectively. The Mn₃O₄ nanoparticles could be conditioned and inverted to birnessite-type MnO₂. A specific capacitance of 239 F/g is obtained for the conditioned Mn₃O₄ nanoparticles prepared in NH₃ solution at a current rate of 0.25 A/g. Therefore, the Mn₃O₄ nanoparticles obtained in NH₃ solution can be a promising electrode materials for supercapacitors.

Key words: supercapacitor, manganous manganic oxide, chemical precipitation, electrochemical properties