Diversified Fabrication Of Graphene/Porous Carbon Film And Their Application Research In Supercapacitors

Recent years,fabrication of graphene and porous amorphous carbon materials and their application in energy storage devices have attracted great attention in the scientific researching.As a new type of two-dimensional(2D)nanostructured carbon material,graphene has strong mechanical strength,higher carrier mobility and electrical conductivity.Porous amorphous carbon materials have high specific surface area,physical and chemical stability and relatively low fabrication cost.So,graphene and porous amorphous carbon materials are the ideal electrode material for the application in supercapacitors.In this paper,graphene,porous carbon film with different structures are fabricated by ambient pressure chemical vapor deposition(APCVD)which is widely used for the fabrication of carbon materials recently.The electrochemical analysis shows that the carbon films have good electrochemical performance in the application of supercapacitors.Meanwhile,the electrochemical performance of supercapacitors can be further improved by depositing metallic oxide MnO2.Detailed research contents are the following:Firstly,thickness controllable multilayer graphene(MGF),porous carbon film(PCF)and hybrid carbon film(HCF)composed of MGF and PCF were fabricated by APCVD with nickel foil as substrate,methane as the carbon source and ferric chloride solution as corrosive liquid under different experiment method.The results showed that the MGF could be rapidly exfoliated under natural environment;the pore size of PCF was on the range of tens of nanometers.The fabrication of the MGF,PCF and HCF was relatively simple and the experimental process was easily controlled.Meanwhile,the prepared HCF could be moved to any required substrates.The HCF could be directly applied to the of the supercapacitor electrode material,and the maximum area specific capacitance reached 0.89 mF/cm2.At the same time,the supercapacitor based on the HCF has high rate and high power density.Secondly,2D PCF/Ni double layer composite material was fabricated by APCVD with nickel foil as substrate,methane as the carbon source and ferric chloride solution as corrosive liquid.APCVD method was used to fabricating MGF on the surface of nickel foil,and then the MGF was rapidly exfoliated leaving the nickel.PCF/Ni double layer composite material could be acquired by partly etching the nickel using the ferric chloride solution.The thickness of the PCF could be controlled by the etching time.The PCF/Ni could be directly used in flexible supercapacitor.Maximum area specific capacitance of the supercapacitor reached 0.64 mF/cm2.Meanwhile,the supercapacitor based on PCF/Ni has good flexibility,long cycle life,good stability and relative high energy density.Thirdly,3D foam-like carbon materials(3D FCM)with different structures were fabricated by APCVD under different growth temperature with nickel foam(NF)as substrate,methane as the carbon source and ferric chloride solution as corrosive liquid.By controlling the growth temperature during APCVD process,the structures of the 3D FCM were:1)3D porous carbon,2)3D hybrid carbon materials composed of porous carbon film and multilayer graphene film,3)free-standing 3D hollow graphene.Especially,the free-standing 3D FCM,in which porous carbon film adhered to the inner surface of hollow graphene,was found to be promising alternatives for the electrode materials of energy storage devices because of their interconnected hierarchical porous structures and high electrical conductivity,which provide a more favorable path for charge penetration and transportation.Therefore,it was an ideal electrode material for supercapacitors.The supercapacitor based on the 3D FCM exhibited good capacitance and rate performance.Maximum area specific capacitance of the supercapacitor reached 0.72mF/cm2.Finally,3D multilyer graphene film/nickel foam(3D MGF/NF)structure was fabricated by APCVD with nickel foam as substrate,methane as the carbon source.Then 3D manganese dioxide/MGF/NF(3D MnO2/MGF/NF)structure was fabricated by an improved chemical bath deposition under neutral condition.In the 3D MnO2/MGF/NF strcture,MGF serves as a buffer layer to improve the conductivity of MnO2 and enhance the interface contact between MnO2 and NF.The 3D MnO2/MGF/NF structure can give full play to their respective advantages of each component and has high electrical conductive,large surface area,and close interface contact.The flexible supercapacitor based on 3D MnO2/MGF/NF hybrid structure exhibits good electrochemical performance.Maximum area specific capacitance of the supercapacitor reached 714 mF/cm2.Meanwhile,the supercapacitor had high cycle life and exhibits minimal change in capacitance under dynamic bending.