Preparation And Supercapacitance Of Graphene-Based Composites

Energy shortage becomes more and more serious,as a key strategic technology to support the development of renewable energy,high efficient storage-energy technology has become a research hotspot.Supercapacitor as a new energy storage device has been attracted,and the electrode materials are the key technology to the preparation of supercapacitor.Therefore,research on graphene-based energy storage materials has a broad application prospect and practical significance.In this thesis,the preparation of graphene/polyaniline composites and their electrochemical properties are focused on.Oxidized graphene(GO)was prepared by the modified Hummers' method using flake graphite as raw materials.TPA-GO was prepared by modifying GO by 1 mg/ m L terephthalic acid(TPA)aqueous solution of ammonia.The microstructure and morphology of GO and TPA-GO were characterized by XRD,SEM and FT-IR.The oxygen-containing functional groups of TPA-GO were increased,which enhanced hydrophility.TPA-GO appeared obvious lamellar structure,which indicated that TPA promoted the exfoliation of the GO.Polyaniline(PANI)with good structure and good polymerization degree was successfully prepared by in-situ chemistry polymerization technology.The effects of different composite ratios of GO and PANI on the microstructure and morphology of GO/PANI composites were investigated.The microstructure,morphology and thermal stability were characterized by XRD,SEM,FT-IR and TG.The optimal combination ratio of GO and PANI was 1: 9,GO / PANI1:9 were composited more completely at this ratio.The TPA-GO/PANI1:9 composites were successfully prepared by in-situ chemical combination method at the ratio of 1: 9.The microstructure,morphology and thermal stability were characterized by XRD,SEM,FT-IR and TG.The interfacial distance of GO and the oxygen-containing functional groups increased after TPA modification,TPA-GO was composited with PANI more completely.And the microstructure of the composites was more regular and uniform,no obvious agglomeration was observed.The micro-morphology of GO/PANI composites was improved after TPA modification.The reduction effects of Hydrazine hydrate to GO/PANI1:9 and TPA-GO/PANI1:9were studied.The GO/PANI1:9 and TPA-GO/PANI1:9 were successfully reduced to r GO/PANI1:9 and TPA-r GO/PANI1:9 at 95 ? for 24 h by hydrazine hydrate reductant.The microstructure,micro-morphology and thermal stability of r GO/PANI1:9 and TPA-r GO/PANI1:9 were characterized by XRD,SEM,FT-IR and TG.The functional groups in the composites after reduction were decreased obviously,but still maintained the same regular morphology as that before reduction,indicating that hydrazine hydrate successfully reduced GO into r GO,while it did not destroy the micro-morphology of composites.GO/PANI1:9,TPA-GO/PANI1:9,r GO/PANI1:9 and TPA-r GO/PANI1:9 were fabricated into electrodes,respectively.The composite electrode,calomel electrode,and platinum electrode were acted as the working electrode,reference electrode and auxiliary electrode,respectively,and 1M H2SO4 solution were used as electrolyte.Cycle volt-ampere curve and ac impedance spectroscopy were tested by three electrode system.The specific capacitance of the four composite electrodes were 192.20 F·g-1,221.91F·g-1,329.03 F·g-1and 347.22 F·g-1at the scanning rate of 10 m V/s,respectively.The results indicated that both TPA modification and hydrazine hydrate were contributed to improve the specific capacitance of composites.