Preparation And Characterization Of Manganese Dioxide Electrode Material For Supercapacitor

Due to the superior theoretical capacitance?1370F/g?,lower price and environment friendly,MnO₂ has always been regarded as one of the best materials for supercapacitor electrode.MnO₂ has several crystallographic phases,such as ?,?,?,?,? etc.As well known,the performance of the electrode materials has large relationship with MnO₂ crystalline states.Generally,the performance of these phases has this law: ? ? ? > ? > ? > ?.Here,analytical grade glucose and KMnO₄ were used,and then carbon nanospheres and tremella-like ultrathin MnO₂ have been synthesized.SEM,TEM and XPS were used for their characterization.Cyclic voltammetry,galvanostatic charge-discharge and electrochemical impedance spectroscopy were performed for their electrochemical performance,The main findings are as follows:.?1?Uniform and monodispersed colloidal carbon spheres were prepared through solvothermal method using glucose as the source of carbon resource.Then,SiO₂ was used as the template to synthesis of hollow carbon spheres.?2?Through one-pot reaction between colloidal carbon spheres and KMnO₄,C@MnO₂ composites have been synthesized.The influence of reaction time on the structure and property of the material was discussed.By changing the reaction time,the thickness of the MnO₂ coating layer and the pore structures of manganese oxide/carbon sphere composites?C@MnO₂?were successfully tuned.Based on the electrochemical characterization,it was found that the optimal aging time was 6 h for a proper pore structure as well as MnO₂ thickness and the highest specific capacitance of 170 F/g?at a current density of 0.1 A/g?is obtained.?3?Tremella-like ?-MnO₂ has been synthesized through solvothermal method using KMnO₄ as the source of Mn.The influence of different quality of the raw material on the microstructure and electrochemical property of MnO₂ was discussed.and then test the electrochemical of the MnO₂.It was found when the quality of raw material was 0.2g,the reaction temperature was 180?,the production had the best electrochemical property.