Preparation Of Modified Polyaniline/Graphene Oxide Supercapacitor Materials And Study On Their Capacitance Properties

Polyaniline(PANI) and graphene oxide(GO) have both been the supercapacitorelectrode materials of extensive research in recent years. In this paper, severalmethods of preparing PANI were first investigated and one best method wasadopted, then the properties of the modified polyaniline prepared by aniline andp-phenylenediamine were also explored. Furthermore, surpercapacitor material ofgraphene oxide prepared by the improved hummers’ method from the graphite wasstudied. In addition, graphene oxide/modified polyaniline supercapacitor compsitewas synthesized via situ emulsion polymerization, and the structure andcapacitance performances of the supercapacitor materials were studied throughcyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance,fourier transform infrared spectroscop and thermal gravimetric analysis.The results are as follows:(1)In the three methods of preparing polyaniline, the method of emulsionpolymerization(EMP) possessed a high yield of86.7%, a little lower than theyield(93.3%) of water-polymerization(WAP) but more higher than the yield(68.9%)of electrochemical polymerization(ELP). In charge-discharge tests of1M sulfuricacid at a constant current density of1A/g,the PANI synthesized via situ emulsionpolymerization exhibited the specific capacitance of388F/g, higher than thecapacitance of PANI-WAP(281F/g) and PANI-ELP(366F/g). By the furthercharacterization of electrochemical impedance, the PANI-EMP showed the lowestcharge transfer resistance (0.75). Through a comprehensive evaluation,PANI-EMP exhibited a higher specific capacitance and the emulsionpolymerization method could be considered as the best method of the three.(2)The specific capacitance of the modified polyaniline(poly(AN-p-PDA))material synthsised by anline and p-phenylenediamine via situ emulsionpolymerization could be improved along with the increase of p-phenylenediamineand aniline within a certain percentage. With the molar ratio of aniline andp-phenylenediamine of8:2, the maximum specific capacitance of thepoly(AN-p-PDA) material could reach550F/g (1A/g), which has been greatly improved and was162F/g higher than the pure polyaniline. However, as the contentof the p-phenylenediamine was further increased, the specific capacitance of thepoly(AN-p-PDA) displayed a gradual downward trend until the poly(p-PDA)(303F/g) was acquired. The poly(p-PDA) had a charge transfer resistance of2.07,much higher than the poly(AN-p-PDA) synthesized with the molar ratio ofp-phenylenediamine and aniline of2:8. Further analysis of the FT-IR and the TGshowed that the copolymerization of p-phenylenediamine and aniline couldincrease the pseudocapacitance of the poly(AN-p-PDA) material through increasingthe content of quinone rings and keeping on the similar conductive structurewhich could pass the charge as the pure PANI.(3)A composite supercapacitor material was successfully synthesized from theaniline, p-phenylenediamine and the graphene oxide of bettle cycle performance viasitu emulsion polymerization. The composite capacitance was between thecapacitance of poly(AN-p-PDA) and the double layers capacitance of the grapheneoxide. When the composite material had a low ratio of graphene oxide, itscapacitance was much closer to the poly(AN-p-PDA), but the cycle performancecould be significantly augmented.