Effect of heat treatment on the electrochemical properties of Mn oxide-based powder prepared using a wet chemical process

Manganese oxide-based powder was synthesized through a wet chemical process using manganese(II) chloride tetrahydrate. The powder was heat-treated for five hours at temperatures ranging from 200°C to 800°C. Based on the scanning electron microscopy (SEM) analysis, as the heat treatment temperature increased, the surface roughness increased. In addition, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses confirmed that, as the heat treatment temperature increased, the oxidized state of manganese changed from Mn₃O₄ to Mn₅O₈ and then to Mn₂O₃. Electrodes were fabricated using the individual manganese oxide-based powders and analyzed via half-cell cyclic voltammetry (CV) on the basis of 5 mVs^-1. The sample heat-treated at 200°C showed the highest performance with a specific capacitance value of 207.4 Fg^-1 and was identified as having the best electrode characteristics, as determined by charge-discharge tests and electrochemical impedance spectroscopy (EIS) analysis.