Preparation And Electrochemical Performance Of Graphene/NiCo₂O₄ Composite Materials

Electric double layer capacitor and electrochemical pseudocapacitor have advantages and disadvantages because of their different chemisms.An effective way to obtain higher power density and energy density is to combine the characteristics of them and using different electrode materials as positive and negative.In this work,we prepared NiCo₂O₄ composite for supercapacitor electrode material by a co-precipitation way and its electrochemical properties were also studied.Graphene/NiCo₂O₄ composite was synthesized by a hydrothermal method.XRD,Raman,SEM,TEM were used to characterize the structure and morphology.The results indicated that cobalt and nickel existed in the form of NiCo₂O₄,and the morphologies varied from flower-like balls to urchin-like balls.Electrochemical tests showed that the sample prepared in the solvent in which the ratio of H₂O to ethanol was 1:1 reached 1808 F/g when the current density was 1 A/g.And the capacitance remained 80.0%after 1000 cycles at a current density of 10 A/g.NiCl₂·6H₂O,CoCl₂·6H₂O and grapheme oxide were used to synthesized RGO/NiCo₂O₄ composite by a co-precipitation method.The morphology of the composite maintained the layered structure of grapheme and the NiCo₂O₄ dispersed on the surface of grapheme sheets.Electrochemical tests showed that the specific capacitance of NiCo₂O₄ composite was 991.4 F/g at a current density of 1 A/g,and remained 91.3%at a current density of 10 A/g after 1000 cycles.