Preparation And Electrochemical Properties Research Of Hybrid Supercapacitors

Among transition metal oxides, Mn O₂ is one of the most promising electrode material for supercapacitors thanks to its high theoretical capacity,environmental compatibility, safety, abundant resources and cost effectiveness.And graphene owing to its large specific surface area, small resistivity, high electron mobility, and excellent electrochemical stability, has received much attention as a broad range of application in supercapacitors. In this experiment,the positive active materials are prepared through a hydrothermal process, and reduced graphene oxide?RGO? as cathode active material, assemble to obtain the hybrid supercapacitors with good performance.The positive active materials are successfully fabricated using hydrothermal method. According to the orthogonal table to determine the best reaction conditions: concentration of reactants is 0.05 mol/L, hydrothermal time is 10 h,hydrothermal temperature is 150 ?, p H is 7 and ratio of reactants is 1: 1. Under this condition, the specific capacitance of Mn O₂ is 66 F·g-1, after doping ferrum or nickel, the specific capacitance of 4 mol%Fe-Mn O₂ is 119 F·g-1, and the specific capacitance of 2 mol%Ni-Mn O₂ up to 111 F·g-1, continue to composite RGO, the specific capacitance of 4 mol%Fe-Mn O₂/2 wt%RGO is 144 F·g-1, and the specific capacitance of 2 mol%Ni-Mn O₂/2 wt%RGO increased by 23%,indicating that doping ferrum, nickel or composite RGO can greatly enhances the electrochemical performance of Mn O₂.GO is prepared by Hummers method, and then using hydrothermal method reduction 24 h to obtain RGO at 180 ?. Morphology, structure of the samples are evaluated by X-ray diffraction?XRD?, Transmission electron microscopy?TEM? and Fourier transform infrared spectrometer?FT-IR?, by electrochemical workstation measured the specific capacitance of RGO is 110 F·g-1.According to the conservation of charge can matching the quality of positiveactive materials and cathode active material. 4 mol%Fe-Mn O₂/2 wt% RGO,2 mol%Ni-Mn O₂/2 wt%RGO as positive active materials and RGO as cathode active material can obtain the hybrid supercapacitors, by electrochemical workstation can measure the specific capacitance of 4 mol%Fe-Mn O₂/2 wt%RGO//RGO is 51.2 F·g-1, and the specific capacitance of 2 mol%Ni-Mn O₂/2 wt%RGO//RGO is 45.6 F·g-1.