Preparation Of Graphene/nickel Foam Composites For Supercapacitors And Study Of Their Energy Storage Propertie

In recent years,the design and manufacture of supercapacitor(SC)has been highly focused on energy storage equipment.Compared with traditional capacitors,SC mainly uses electrode materials with high specific surface area and special media to obtain high capacitance,and also has the advantages of high power density and extremely high cycle life.At present,graphene materials are widely used in SC design and manufacturing,mainly because graphene is a twodimensional cellular network with sp2 hybrid carbon,which has many remarkable properties,such as large specific surface area,huge electron mobility,high mechanical strength,high thermal conductivity,excellent chemical stability,etc.However,because stacking of graphene can limit these excellent properties of graphene,many people are working on developing 3D graphene materials,mainly 3D graphene materials because they can prevent the stacking of graphene sheets,in order to preserve the physical and chemical properties of graphene in two dimensions.(1)This paper mainly studies the preparation of three-dimensional graphene/nickel foam composite materials by electrophoretic deposition,and the construction of three-dimensional porous,high conductivity,large specific surface area,high recycling of the supercapacitor electrode.GO contains a large number of negative oxygen-containing functional groups(OH-,COOH-),showing a very good hydrophilicity.Go dispersion is configured as a suspension of electrophoretic deposition.Because GO contains a large number of oxygen-containing functional groups,GO sheets are electronegative GO/NF precursors can be obtained by directional migration of GO nanosheets to nickel foam substrate as anode by electrophoretic deposition,and then RGO/NF composites can be obtained by reducing GO/NF.In this paper,we discussed the influence of the concentration of the suspension,the deposition voltage and the deposition time on the electrophoretic deposition,and also discussed the feasibility of the preparation of graphene foam by removing the NF skeleton.(2)HRGO/NF is obtained by water plasticizing foaming reduction method(HPF).Water plasticizing foaming is mainly water plasticizing and foaming.Water plasticizing is to change GO sheet into a plasticizing state so that foaming agent is easier to penetrate.Foaming is the use of foaming agent to make OH-and COOH-on GO form bubbles to escape from the graphene layers and form a more porous structure to increase the specific surface area of the electrode.Meanwhile,due to the removal of oxygen-containing functional groups,the conductivity of the electrode is also greatly improved.Under the action of HPF,obvious expansion occurs between graphene layers.resulting in smaller pores,increasing the specific surface area of the electrode,providing a fast transmission channel for ion transport and ion diffusion,and increasing the capacitance value of the SC electric double layer.When the current density is 0.5 A /g,the specific capacitance value is 195 F/g.When the current density is increased to 8 A/g,the specific capacitance is 53% of the initial specific capacitance.When the scanning rate is 100 m V/s,the CV curve is still rectangular after 10000 scanning times,and the cycling rate can be maintained at 98%.(3)Using graphene or carbon nanotubes(CNT)alone as electrode materials for SC,the capacity performance is not ideal.In order to further enhance its value in the field of energy storage,RGO/CNT/NF composite material was developed by electrophoretic deposition.The surface of functionalized CNT contains a large number of oxygen-containing functional groups like GO,and both GO and CNT can be directionally transferred to nickel foam matrix by electrophoretic deposition.Because the conductivity of graphene in the single layer is very good,but the conductivity between layers is greatly reduced,CNT is interspersed between the graphene sheets after electrophoretic deposition,and plays a pivotal role in the transfer of electrons between the graphene layers,greatly improving the conductivity of the electrode.The RGO/CNT/NF electrode produces a capacitance of 431 m F/cm2 at a current density of 1m A/cm2.