Study On Preparation And Properties Of Novel Carbon And Maganese Oxide Nanocomposite

Over the past few years,supercapacitors have attracted a great deal of attention due to their advantages such as high power density,environmental friendliness and long service life,and shown a bright,promising prospect in areas like new electronic and renewable energy system,which were thought to be one of the most promissing elctrochemical energy storage devices.The composite of carbon-based materials and conducting polymer and transition matel oxides have been the research hotspot for several years because of their abundance,low cost,environmental friendliness and good electrochemical performance.Among them,graphene and manganese oxide composite material was mostly studied by researchers worldwide.However,the surface area of graphene material enlarges plentifully,but it can be hardly used because the graphene inclines to agglomerate during the process of reduction,which makes the materials lost the excellent properties of graphene.In this dissertation,we take certain measures to synthesize graphene oxide and nanotubes,so that we can increase the available surface areas.In the subsequent process,the carbon-based material is compounded with manganese oxide and tests for its electrochemical properties in a simple method.The nano manganese oxide was deposited on the surface of graphene oxide in isopropanol-water binary system.The characterization methods of SEM and XRD and Raman spectra and XPS were carried out to analyze the physical characteristics of the samples under feeding rate and cooling rate.Comparing with CV and galvanostatic charge/discharge curve and of materials by different feeding rate and cooling rate in the reaction process,it was found out that the feeding rate of graphene oxide and manganese oxide was equal to 1:9,the performance reached optimal.Compared with reflux cooling,the water quench showed excellent performance.S pecific capacitances calculated by galvanostatic charge/discharge curve were 312.87 F/g and cycle performance reached 85.12% for quickly cooling solution with ice water(about 5 ?)and 253.12 F/g and 88.16% for reflux cooling(starting temperature at 80 ?)to room temperature.On the basis of the graphene oxide-manganese oxide composite,the carbon nanotubes with different charges were introduced and combined with graphene oxide,the effects of the carbon nanotubes with different charges and graphene oxide were analyzed subsequently.By the same means of physical properties analysis and performance analysis,we could find that the negatively charged carbon nanotube was slightly better than the positively charged carbon nanotbues.When the proportion of carbon nanotubes and grahene/manganese oxide was 1:1:6,the properties of the material were optimized.Specific capacitances calculated by galvanostatic charge/discharge curve were 306.82 F/g and cycle performance reached 76.87%.In addition,by keeping the ratio of the graphene oxide-mangnaese oxides unchanged,the influence of different carbon ratios was analyzed.It was found that the properties of the carbon nanotubes were not improved when the content of carbon nanotubes relatively increased,which might be the agglomeration of carbon nanotubes in the subsequent process.