Influence of calcination temperature on physical and electrochemical properties of MnO2 nanoparticles synthesized by co-precipitation method

Manganese dioxide nanoparticles were successfully synthesized by co-precipitation method using manganese acetate and potassium permanganate as the starting materials and calcined at 200-500 degrees C for 4 h in ambient air. Structural, morphological and electrochemical properties of all samples were investigated by X-ray diffraction technique (XRD), scanning electron microscope (SEM) and cyclic voltammetry technique (CV), respectively. The symmetric electrochemical cells were fabricated on 304-stainless steel as the electrode by doctor blade technique using polyvinylpyrrolidone (PVP)-KI as the gel electrolyte. The XRD results reveal that tetragonal structure of MnO2 could be synthesized by co-precipitation process with calcinations temperature at 400 degrees C for 4 hr. SEM images indicate that the size of MnO2 quasi-spherical powders are in nanoscale and transform into short rod under calcination temperature at 500 degrees C. The electrochemical properties results indicate that the electrochemical cell of MnO2 calcined at 300 degrees C with PVP-KI as the gel electrolyte shows a highest specific capacitance about 90.87 F/g at a scan rate of 100 mV/s.