Effect of microstructure on performance and working mechanism of MnO2-PEDOT supercapacitors based on nonaqueous electrolytes

Abstract

In this work we demonstrate the impact of synthesis conditions on the properties of stable nanostructured MnO₂ and their application as electrode material in supercapacitors. Samples synthesized by hydrothermal method were characterized by XRD, XPS, SEM, BET surface area and the correlation with the electrochemical performance of constructed prototype supercapacitors was discussed. The morphological study of the as-synthesized MnO₂ samples shown the morphology consisting of nanorods for pH value of 2.5 and cauliflower shape for pH of 3 and 6.5. The XRD study revealed that at low pH a α-MnO₂ is formed whereas an increase of pH during synthesis leads to birnessite phase formation. The electrochemical studies, for 5 % KNO₃ dissolved in dimethyl sulfoxide (DMSO) used as an electrolyte, shown that the birnessite MnO₂ structure exhibits much better electrochemical behavior of constructed supercapacitors comparing to α-MnO2. The observed electrochemical behavior can be explained by the microstructure differences of prepared materials.