Nanostructural Tailoring And Electrochemical Performance Of Co₃O₄/Graphene Composite Electrode Materials

In order to satisfy the current social urgent requirement,scientific research has been focused on electrochemical energy storage devices during the past decades.In this paper,we produced Co3O4-based material as supercapacitive electrode by using graphene as the supporting substratum for higher energy density and power density.As the shape of electrode materials is connection with its electrochemical properties,Co3O4/graphene composites with different structures were successfully manufactured,and their electrochemical properties were studied.The research is as follows:(1)Co3O4 nanosheets and graphene oxide were assembled into layer-by-layer structure via the principle of different charges attracting each other with poly dimethyl diallyl ammonium chloride(PDDA)as the surfactant.The self-supported structure expends the effective surface area with more active points,at the same time,porous structure is advantageous for ion exchanging between electrode and electrolyte.This Co3O4/graphene composite showed high specific capacitance of 623.84 F/g,508.08 F/g and 508.08 F/g at scan rates of 5 mV/s,10 mV/s and 20 mV/s,respectively.which not only presents a superior specific capacity value,but also a good frequency of retention.(2)ZIF-67 was coated by graphene oxide nanosheets through an in situ growth method with the particle size controlled at approximately 103 nm.After been calcined at high temperature,this Co3O4/graphene composite achieves large specific surface area with increasing interface between Co3O4 and graphene oxide,resulting in widened path for charge transfer and improved electron transfer rate.This composite material has much higher energy density and power density than lots of such kind of materials.