Preparation And Properties Of Bimetal Oxides/RGO Composites

With the vigorous development of the electric vehicle industry,people’s demand for renewable energy and clean energy is increasing,and the requirements for batteries are becoming higher and higher,prompting the research of new energy storage materials.Electrochemical capacitors have several times more energy storage effect than traditional batteries,and are more durable,with fast charging and discharging speed,low loss,and no need for repair and maintenance.Metal oxide electrode materials have higher power and energy density,and the performance of bimetal oxides is more stable than that of single metals.However,the internal resistance of metal oxides is greater than that of carbon materials.Graphene has a large number of oxygen-containing functional groups,good hydrophilicity,and can be modified,hybridized,and functionalized on the surface.Combining both graphene and metal oxides,graphene’s excellent cycle stability and high capacity performance of metal oxides can effectively avoid the problem of graphene’s easy agglomeration on the one hand,and can improve the electrolyte and The contact area of the electrode material,so that the overall performance of the composite material can be greatly improved.In this paper,graphene materials were prepared by an improved method.Through the study of the combination of zinc manganese oxide,nickel cobalt oxide,nickel manganese oxide and graphene,different preparation methods and different ratios of bimetal oxide electrode materials were discussed The impact of energy storage,and the impact of graphene-based structure on energy storage materials.The main contents are as follows Graphene was prepared by improved hummers method.Graphene oxide was synthesized by changing the composition of the oxidant in the low temperature stage,and reduced to make a graphene solution.The Raman spectroscopy was performed on the two samples.The Raman spectroscopy showed that the improved graphene material had a higher degree of graphitization than the traditional method,and had better layered resolution.（1）Composite materials of zinc manganese oxide and graphene were prepared by solvothermal method and hydrothermal method.Under the scanning electron microscope: the composite material prepared by solvothermal method exhibits nanospheres attached to the surface of graphene;the composite material prepared by hydrothermal method is obviously nanosphere,and Zn Mn₂O₄ is deposited on the surface of graphene.The addition of graphene promotes the dispersion rate of Zn Mn₂O₄,so that the spherical microparticles of Zn Mn₂O₄ are refined into nanoparticles.The three-electrode system was tested in 1mol/L Na OH electrolyte,and the mass specific capacitance of the solvothermal method was 69F/g,59 F / at the scanning rate of 10 m V/s,20 m V/s,50 m V/s,100 m V/s.g,41F/g,26F/g.The mass specific capacitance in hydrothermal method is 92F/g,75F/g,52F/g,34F/g.When the current density is 2A/g,5A/g,10A/g,the specific capacitance of solvothermal method is 763F/g,95F/g,89F/g,and the specific capacitance under hydrothermal method is 127F/g,79F/g,64F/g.（2）Ni Co₂O₄/RGO was prepared by solvothermal method and co-precipitation method.It was found by scanning electron microscope that Ni Co₂O₄/RGO prepared by solvothermal method can obviously observe the uniform growth of Ni Co₂O₄ in the shape of pompon on the surface of RGO,and Form a needle-like arrangement.Ni Co₂O₄ in the Ni Co₂O₄/RGO composite prepared by solvothermal method showed needle shape,and the sheet-shaped graphene layer could be clearly observed.There is a clear gap between the needle and the needle,which is conducive to the diffusion of ions in the gap.For composite materials prepared by precipitation method,when urea is used as a precipitant,high-density one-dimensional Ni Co₂O₄ nanowires grow uniformly on the surface of RGO and form a highly oriented nanowire array.The diameter of the nanowires is about 40 nm and the length is about It is several microns long.The three-electrode system was tested in a 1mol / L Na OH electrolyte,and the scan rate was 10 m V/s,20 m V/s,50 m V/s,100 m V/s,and the mass specific capacitance of Ni Co₂O₄/RGO composite under solvothermal method was 935F/g,837F/g,694F/g,510F/g.The mass specific capacitance of Ni Co₂O₄/RGO composite under the co-precipitation method is 1063F/g,942F/g,825F/g,599F/g.In the case of current density of 2A/g,5A/g,10A/g,the specific capacitance of Ni Co₂O₄/RGO composite under solvothermal method is 854F/g,830F/g,735F/g,and Ni Co₂O₄/RGO under coprecipitation method The specific capacitance of the composite is 913F/g,861F/g,794F/g.（3）A composite metal oxide / graphene composite with a nickel-manganese ratio of 1:1 and 3:1 was prepared by a co-precipitation method.Under the scanning electron microscope: the composite with a ratio of 1:1 to nickel-manganese showed a large number of spinel-shaped crystals of various sizes.In composites with a nickel-manganese ratio of 3:1,the spinel crystals are reduced due to the increase in nickel content.Instead,a unique porous layered structure is generated.It is judged that the excessive addition of nickel makes the unit cell smaller and affects the passage of ions.At the same time,a lattice defect,that is,a hole structure is generated.The three-electrode system was tested in a 1 mol/L Na OH electrolyte.At a scan rate of 10 m V/s,20 m V/s,50 m V/s,100 m V/s,the nickel-manganese ratio 1:1 composite electrode has a mass specific capacitance of 446F/g,255F/g,131F/g,73F/g.The mass specific capacitances of the nickel-manganese 3:1 composite electrode are 217F/g,124F/g,59F/g,34F/g.When the current density is 2A/g,5A/g,10A/g,the specific capacitance of the Ni-Mn ratio 1:1 composite electrode is 1784F/g,1687F/g,830F/g,and the specific capacitance of the Ni Mn₂O₄/RGO composite.It was 2917F/g,1926F/g,738F/g.