Research On Preparation And Electrochemical Properties Of Functionalized Graphene/Polyaniline Composites

Recently, supercapacitors with integrated properties from traditional capacitors andbatteries emerge as a new candidate device for energy storage, due to their high energydensity, high power rating, long cycling life and low price. As the core of supercapacitor,there are many electrode materials employed, which include carbon material, conductingpolymer and metal oxide. These materials are unique in advantages, so as the defects.Therefore, it is highly necessary to incorporate these individuals together for the detectionfor high-performance supercapacitor electrodes.Firstly, graphene oxide （GO） was functionalized with octadecylamine （ODA） and p-phenylenediamine （PPD）, respectively, then reduced by hydrazine hydrate, producingODA functionalized graphene （ODA-G） and PPD functionalized graphene （PPD-G）. Thesedimentation experiments show that both ODA-G and PPD-G could be dispersed well inchloroform and absolute ethyl alcohol for a long time without further aggregation,underlying the solution mixing for PANI-graphene composites.Secondly, conducting polyaniline （PANI） was synthesized by the traditional chemicaloxidation method, for which the oxidizer ammonium persulfate （APS）, aniline monomers（An）, and protonation solution hydrochloric acid were employed. The experimental resultsshow a highest electrical conductivity could be obtained up to0.0223S/cm, when thereaction was conducted at0⁵℃, with a concentration of hydrochloric acid of1.5mol/Land a APS to An mol ratio of1:1, and the resulting specific capacitance doped withdifferent conductive reagents reached274F/g in the maximum value.Finally, ODA-G/PANI and PPD-G/PANI composites were prepared using solution-mixing method. The electrochemical measurements conducted in1mol/L H₂SO₄withcurrent density0.6A/g show that the specific capacitance of the two composites couldreach641and378F/g, respectively, higher than that of pure PANI. In comparison, thespecific capacitance of ODA-G/PANI system is higher than that of PPD-G/PANI system. Also, PANI loaded with2wt%ODA-G bears an optimal value of641F/g, and its200-cyclic stability remains96%, higher than76%for pure PANI. These indicate that ODA-Gdoped as a conductive agent as well as reinforcing frame benefits the elevation of thespecific capacitance of composites and its stability, prolonging the service life ofcomposite electrodes of this kind.