Preparation And Analysis Of Reduced Oxidized Porous Graphene Material And Its Application In Supercapacitors

As the problem of environmental pollution is increasingly attracting people's attention,vigorously promoting the use of clean and renewable energy has become an important direction of today's social development.At the same time,energy storage has become a key issue for whether clean energy can be widely used,and how to improve energy storage capacity has become a problem facing scientists.As a new kind of energy storage device,supercapacitors and lithium-ion batteries are very important in the area of energy storage.As we all know,lithium batteries have a high energy density and a strong energy storage capacity,but power output is restricted by their own shortages,and they cannot output stored electrical energy at high power,which hinders their development and wide application.The characteristic that the super capacitor can be quickly charged and discharged has created its advantage of high power density and made up for the shortcomings of the lithium battery.However,the energy density of supercapacitors is still smaller than that of lithium batteries.Further improving the energy storage capacity of supercapacitors is the direction that researchers need to work hard.This experiment aims to synthesize reduced-oxidized porous graphene,by adding template agents(MgO,ZnO),to avoid the stacking of graphene sheets and change the structure of graphene sheets to achieve this goal.The addition of different templating agents is to study the different effects of different templating agents on changing the structure of graphene and the different performances in electrochemical tests.The specific work content of this paper is as follows:(1)On the basis of referring to the Hummer's method,by adding a template agent to the synthesis process,the graphene sheet morphology was changed,and a reduced-oxidation porous graphene material with a zigzag surface was successfully prepared to avoid graphite The problem of easy stacking of ene in the synthesis process.Through SEM observation,it can be clearly seen that the graphene prepared after adding the template has a fluffy surface with a similar pore structure.It can also be seen in the pore size distribution diagram that the reduced-oxidized porous graphene(M-rGO)prepared by adding MgO as a template agent and the reduced-oxidized porous graphene(Z-rGO)prepared by adding ZnO as a template agent did not add any template Compared with the reduced graphene oxide(N-rGO)prepared,the pore content is significantly higher in the 7-100nm pore size range,which proves that the addition of the template agent increases the porosity of the mesopores and macropores of the material.Various other characterizations also prove that the process of the template agent will reduce the degree of graphitization of the material and the wettability of the material surface,but to a lesser extent.(2)In 6 M KOH,under the three-electrode(working electrode,counter electrode,reference electrode)system,verify the effect of the addition of template agent on the capacitance performance of the synthesized graphene material.After calculation,when the current density of N-rGO synthesized without adding the template agent is 1 A·g-1,its specific capacitance is 173 F·g-1,while the current density of M-rGO and Z-rGO synthesized with the template agent is at 1 A·g-1,their specific capacitance are 266.8 F·g-1 and 250 F·g-1,respectively.It shows that the specific capacitance value of the material has been improved after adding the template agent.(3)Explore the different sizes of the added template agent,resulting in differences in the morphology and electrochemical performance of the synthesized reduced-oxidation porous graphene material.Since the added template agent MgO is larger in particle size than the template agent ZnO,the synthesized M-rGO is also higher in mesopore and macropore porosity than Z-rGO.In electrochemical test,the specific capacitance of M-rGO at high current density of 10 A·g-1 is 202 F·g-1;when the current density becomes low(0.1 A·g-1),the specific capacitance reaches at 293.2 F·g-1.When Z-rGO is 10 A·g-1,the capacitance is 164 F·g-1,and when 0.1 A-g-1,the specific capacitance becomes 305 F·g-1.It means that adding a larger size template can increase the specific capacitance of the material at a higher current density;adding a smaller size template can increase the specific capacitance at a lower current density.This is a new reference design for future materials.