Preparation And Electrochemical Performance Of Graphene/Co₃O₄Composite

Composite materials for supercapacitor electrodes integrate the advantages ofvariety of materials, showing a high capacitance characteristics, powercharacteristics, energy characteristics and cycling performance. Therefore,preparation of composite electrode matrials which have cooperative effect becomethe focus today. In this paper, Graphene/Co3O4composite was prepared byelectrochemical method, and its electrochemical performance was studied.Graohite oxidation(GO) was synthesized from flake graphite by modifiedHummers’ method. GO was dispered and mixed with some Co(NO3)2, thendropped onto ITO and dried. Graphene/Co3O4composite was prepared bypotentiostatic method. The SEM、TEM、XPS and Raman were applied to study themorphology and structure of the composite. The electrochemical performance ofdifferent mass ratio composite was studied. The test showed that the morphologyof the composite carry on graphene’s skeleton, present the wrinkle of graphene,Co3O4particles uniformilty distribute on the surface of graphene. When the massratio of Co3O4was16.6%, The composite showed best electrochemicalperformance. The capacitance can reach357F/g in500mA/g and256F/g in3000mA/g,72%of the capacitance was kept. In1000mA/g, the capacitance ofcomposite reached333F/g, after1000cycle of charge and discharge, thecapacitance kept87%.An asymmertric supercapacitor has been constructed with Graphene/Co3O4composite, activated carbon as the negative eleoctrode and studied the influenceof activated carbon’s mass on the performance of supercapacitor. When the massof activated carbon was4.2mg, the supercapacitor got the best performance,reached57.75F/g and41F/g in300mA/g and2000mA/g, respectively. Testresults showed that the asymmertric supercapacitor had good heavy loaddischarge performance. Compared with AC-AC double layer supercapacitors,asymmertric supercapacitors based on Graphene/Co3O4composite and activatedcarbon have more excellent power density and energy density.