Preparation And Supercapacitive Performances Of Layer By Layer Assembled Graphene/Polyaniline Composite Electrode

Owing to the high specific capacitance of Polyaniline(PANI),it is most likely to become a high performance supercapacitor electrode material.However,the volume expansion and contraction caused decline of specific capacitance during the process of charging-discharging.A poor rate capability of PANI electrode was caused by its low conductivity.The structure of PANI electrode would destroyed by high temperature.Therefore,in this paper,Graphene / Polyaniline multilayer films were prepared to improve the problems of PANI electrode through alternate deposition of RGO and PANI,which was based on high conductivity,excellent mechanical properties and heat resistance of RGO.Then,the multilayer films were prepared by mechanical attrition to study the electrochemical supercapacitive performance.The results were showed as following:Graphene(RGO)was synthesized from flake graphite by oxidation-reduction method.The influences of the weight ratio of KMnO4/RGO and reaction time on the structure of GO were investigated by fourier transform infrared(FTIR)spectroscopy,X-ray diffraction(XRD),scanning electron microscopy(SEM),respectively.The optimum conditions of the prepared RGO with some carboxy groups could be confirmed,the mass ratio of KMnO4 to graphite was 3 to 1 and the reaction time was 2h,the pH value adjusted by ammonia of GO was 8,GO was reduced by hydrazine hydrate.Based on the research above,RGO/PANI multilayer films were prepared through alternate deposition of negatively charged RGO and positively charged PANI doped with hydrochloric acid.The influences of assembly solution concentration,assembly time and the pH value of assembly solutionon on the structure of RGO/PANI multilayer films were investigated by Zate,scanning electron microscopy(SEM),respectively.The optimum conditions of the parparation of(RGO/PANI)n multilayer films with excellent conduction and thermal stability could be confirmed,the solution concentration were 1mg/mL,assembly time was 9min,the pH value of RGO was 4,the pH value of PANI was 8.The results demonstrated that the thermal stability and electrical conductivity of PANI electrode were improved by RGO,the electrical conductivity of(RGO/PANI)20 multilayer films were the best,the electrical conduction was 23 S/cm,the weight loss was about 32%,when the temperature was 800? under the protection of argon atmosphere.Furthermore,RGO/PANI composite electrons were prepared by mechanical polishing method.The influences of film layer,scan rate,current density on supercapacitor performance of RGO/PANI composite electron materials were investigated by cyclic voltammetrys(CV),electrochemical impedance spectroscopy(EIS)and galvanostatic charge-discharge tests,respectively.Electrochemical measurements confirmed that the(RGO/PANI)20 composite electrodes exhibited small internal resistance and enhanced capacitance performance.In charge-discharge process,the specific capacitance of(RGO/PANI)20 composite electrode materials' retention is 82%,When the current density increased from 1A·g-1 to 8A·g-1,which showed excellent rate performance.(RGO/PANI)20 composite electrode materials exhibited excellent cyclical stability after 800 cycles at a current density of 1A·g-1.