Electrochemical Deposition Of Graphene/manganese Dioxide Composite Material And Study Of The Electrochemical Properties

Graphene/MnO2 composite electrode was prepared by electrochemical deposition.The graphite oxide was synthesized using the improved Hummers method by stripped in tubular resistance furnace with Graphite.The structure of graphene and graphene/MnO2 composites was characterized by infrared spectroscopy(FT-IR),X ray diffraction technique(XRD),thermogravimetric analysis and differential scanning calorimetry(TGA-DSC).Scanning electron microscope(SEM)was used to observe the morphology of graphene and graphene/MnO2 composites,The capacitance performance of graphene/MnO2 composites was studied in 1M sodium sulfate solution,by electrochemical impedance spectra(EIS),galvanostatic charge-discharge(CP)and cyclic voltammetry(CV)test.FT-IR,TGA-DSC and XRD test results show that composite contains manganese dioxide and graphene.SEM shows the acicular structure of surface growth.And Low-expansion observe MnO2 surface topography appeared crack,the composite is composed of graphene and manganese dioxide.Graphene/MnO2 composite electrode showed.good stability.When single electrode was 1.2 mg and anodic deposition conditions potential was 1 V,the current density was 1 A/g,the specific capacitance of graphene/MnO2 composite electrode is 553.5 F/g in 1 M Na2SO4.After 2000 times of charging and discharging,at the current density of 2 A/g,the initial specific capacitance is 510 F/g,final 468.8 F/g,the capacitance remains 91.9%.An graphene/MnO2-graphene/MnO2 symmetric capacitor was assembled,After 1000 times of charging and discharging,at the current density of 1 A/g,the initial specific capacitance of 47.2 F/g,the last capacitance is 40 F/g remains 84.7%.The energy density and power density is 4.2 Wh/kg and 804.2 W/kg,separately.After 1000 times of charging and discharging,the initial specific capacitance of 38.8 F/g,at the same condition the capacitance of graphene-graphene/MnO2 asymmetric is 37.5 F/g remains 96.6%.The energy density and power density is 3.2 Wh/kg and 800 W/kg,separately.The results show that two kinds of capacitor has little difference,but the stability of graphene-graphene/MnO2 is better.