The Nanostructure Regulation And Supercapacitor Property Of Graphene/Polyaniline Composites

Supercapacitors act as supplementary power sources with the properties of high power density,long cycle life,rapid charge/discharging rates,environmental friendliness and convenience having aroused intense attention.Polyaniline(PANI)is the most common used polymer-based electrode material for supercapacitor with high capacitance thanks to its multiple redox states.However,the poor stability during the fast charge/dischage process and relatively weak flexibility,limit its further application in high performance supercapacitors.In our experiment,Combining PANI with grapheme(RGO)which has great mechanical strength and high conductivity is an effective way to resolve the drawbacks and reserve its advantages.As the microstructure greatly influence the property of the materials itself,so we tried to control the microstructure of RGO/PANI hybrid in order to improve its supercapacitor property.In the first experiment,Phytic acid was here found to be a gelator and proton dopant for PANI.Graphene/polyaniline composites were first synthesized by in-situ oxidative polymerization of aniline in the presence of phytic acid.These two components in the composite can complement each other,meaning keeping the stability of Graphene and high capacity of PANI.The specific capacitance of graphene/PANI composites increased with increasing the graphene content,and a maximum specific capacitance of 855 F/g for PANI composite electrode containing 10 wt%of graphene(PAG10)was achieved,higher than those of pure PANI and GO/PANI electrodes at a constant current of 1 A/g.After 1000 charging-discharging cycles at a current density of 5.0 A/g,PAG 10 electrodes retain 82%(701 F/g).However,pure PANI only retained 38%.In our another experiment,we used ferric chloride(FeCl3)as both dopant and oxidant without protonic acid to synthesize PANI via interfacial polymerization of aniline.The resulting PANI was nanofiber cluster who had only 20-30nm diameter,which was thinner and had higher crystallinity than those nanofibers oxidized by APS.While adding RGO into PANI,PANI nanofibers homogeneously distributed both between the RGO sheets and on the surface forming fiber and sheets 3D structure instead of being cluster.This structure can shorten the ion diffusion paths and increase active sites for the deposition of PANI provided by large surface areas of RGO sheets and the synergistic effect between RGO and PANI.When the PANI composite electrode contained 50 wt%of grapheme(PAG50),its specific capacitance could reach 952 F/g at a constant current of 1 A/g,which was higher both pure PANI and RGO.PAG50 also had long cycle life and electrochemical stability.When the current density changed from 1 A/g to 10 A/g,the capacity of PAG50 still retained 68%.