Preparation Of Graphene/Polyaniline Composites And Their Electrochemical Performance

As a novel,environmental-friendly energy storage device,supercapacitors exhibits outstanding electrochemical performance,which is strongly dependent on the employed electrode materials.In order to overcome both the drawbacks and combine the virtues of graphene and PANI,graphene/polyaniline composites have been extensively exploited recently.Owing to the synergistic effect of carbonaceous nanomaterials and conducting polymer,this kind of composites are expected to possess exceptional electrochemical performance.However,to find a much simpler and straightforward way for fabricating graphene/polyaniline composits with excellent electrochemical performance is currently yet a significant issue.In the thesis,physically integrated and covalently bonded graphene/polyaniline composites were synthesized by two different simple and environmental-friendly ways,respectively.Electrodes based on the composites combining the double layer capacitor mechanism of GO and the pseudocapacitance mechanism of PANI showed excellent capacitor performance,due to the synergistic effects of two different materials.The experimental conditions,matching ratio of components were systematically investigated and optimized,followed by their influence on the composites structure and electrochemical properties which were examined by cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and galvanostatic charging/discharging(GCD).The results achieved are as follows:1.Physically integrated graphene/polyaniline composite(mw-GO/PANI)was synthesized with the introduction of microwave irradiation.The microstructure and electrochemical properties of the samples as electrode materials were studied,respectively.GO exhibited double-layer capacitor property with a low specific capacitance,while PANI as a pseudocapcitance material,showed poor proformance with 200 F/g at 0.5 A/g and 36% capacitance retention after 1000 cycles.The mw-GO/PANI composite synthesized in a microwave-assisted process exhibited uniform morphology and excellent electrochemical performance with 411 F/g at 0.5 A/g and capacitance retention of 73 % after 1000 cycles,much superior to the electrochemical performance of GO/PANI(322 F/g at 0.5 A/g)without introduction of microwave.Furthermore,effects of matching ratio of GO and ANI on the morphology and electrochemical property were studied in detail.The results revealed that mw-GO/PANI showed uniform surface and great electrochemical performance with 411 F/g at 0.5 A/g when the ratio of GO to ANI was 1:10.2.Covalently bonded graphene/polyaniline composites(frGO/PANI)were synthesized via the in-situ polymerization of ANI on EDA functionalized GO.The morphologies and electrochemical performance of PANI,GO/PANI and frGO/PANI were comparatively investigated.It is concluded that the covalently bonded frGO/PANI compoite presented outstanding electrochemical properties with 489 F/g at 0.5 A/g and capacitance retention of 85 % after 1000 cycles which were attributed to the fast electronic transfer rate among components of composite.Effects of the introduction of EDA on the morphology,structure and electrochemical properties of frGO/PANI were systematically investigated.It was found that frGO/PANI composite displayed the most superior morphology and electrochemical performance with the EDA amount of 60 ?L,owing to the amino groups produced in the functionalization process.