Preparation And Energy Storage Performance Of Graphene/Conductive Polymer Composites

This paper has investigated the preparation method and energy storage performance of reduced graphene oxide（rGO）/polyaniline（PANI）composite gel,functionalized reduced graphene oxide（FrGO）/polyaniline nanofibers（PANI NFs）flexible composite film and carbon cloth（CC）/rGO/PANI flexible composite electrode.The materials were characterized by Raman Spectroscopy,Fourier Transform Infrared Spectroscopy,Scanning Electron Microscopy and electrochemical workstation to investigate their microstructure,composition,morphology and further their energy-storage mechanism and applications in supercapacitors.1.The well-dispersed GO solution was prepared by the modified Hummers method. The rGO gel was prepared by hydrothermal method from GO solution,and then the PANI was in-situ polymerized on the rGO porous three-dimensional framework.The optimal control of the loading mass of PANI and the microstructure of the composite was achieved by optimizing preparation process. When the concentration of the aniline monomer was 8 mol L^-1,the density of the rGO/PANI gel reached 1.2 g cm³.While the obtained material exhibits a good mass specific capacitance of 784.3 F g^-1 and a good volume specific capacitance of 941.2 F cm^-3 at a current density of 1 A g^-1 with a good structure ability.2.Functionalized（F）rGO/PANI NFs were prepared by suction filtration of a mixture of GO and in-situ polymerized PANI nanofibers（NFs）followed by hydrothermal treatment and sulfur functionalization of rGO.When the mass ratio of aniline monomer to GO is 5:1,the FrGO/PANI NFs composite films exhibited a high specific capacitance of 692.0 F g^-1 at 1 A g^-1 and an excellent capacitance retention of 53.5%at 40 A g^-1.The assembled all-solid-state supercapacitor using the as-prepared composite films as electrodes exhibits a high capacitance of 324.4 F g^-1 and an energy density 16.3 Wh kg^-1 at 1 A g^-1 and a power density of 300 W kg^-11 with a potential window of 1.2 V.These properties are attributed to the synergistic effect of high specific surface area of the porous graphene substrate, the double layer capacitance of rGO,the pseudocapacitance of in-situ polymerized PANI nanofibers and the redox reaction of sulfur functional groups.3.rGO/PANI composite active material loading were uniformly deposited on a substrate of flexible carbon cloth（CC）by CV cycling method in mixed solution of GO and aniline.For comparation,CC/PANI and Carbon Paper （CP）/rGO/PANI samples were prepared.Electrochemical test results show that the CC/rGO/PANI composite flexible electrode exhibits a high area specific capacitance of 5224 mF cm^-2 and an excellent capacitance retention of 95.2%at current density of 5 mA cm^-22 and 20 mA cm^-2 respectively,which is due to its high area specific active material loading of 9.2 mg cm^-2 and the fast ion diffusion channels provided by the rGO nanosheet.Therefore,The excellent energy storage performance of the prepared rGO/PANI composite gel,FrGO/PANI NFs flexible composite film and CC/rGO/PANI flexible composite electrode have shown application potential for supercapacitors.