Preparation And Electrochemical Performance Of RGO@carbon Ultrafine Fibers For Supercapacitor

Ultrafine fibers prepared via electrospinning have been widely used due to its simple,efficient and extensive source of raw materials,etc.Therefore,ordered array RGO@carbon nanofibers are prepared via the polymer electrospinning methods and thermal treatment pocess in this paper.The study includes four directions:First,study on the preparation and surface modification of graphite oxide(GO).GO was prepared by the improved Hummer method,and GO with small size was obtained by ultrasonic disruption.The influence factors and mechanism of high intensity ultrasound on the size and the thickness of the GO sheet were investigated at varied times(30min,60min and 90min).The GO was characterized by Scanning Electron Microscopy(SEM),X-ray Diffraction(XRD)and infrared spectroscopy(FIRT)and laser particle size analysis(LPZA)and so on.The results showed that GO can be further cutted into ultra small size GO particles with diameter of less than 1 ?m along the GO surface defect area under strong ultrasonic cavitation.Investigation of surface modification of GO.The surface modification of GO was carried out by using siloxane coupling agent(KH550)and surface active agent(sixteen alkyl methyl bromide,polyethylene glycol and sodium oleate).The influencing factors and mechanism of the solubility in N,N'-2-methyl formamide(DMF)were studied via solution stability,FTIR and so on.GO modified by sodium oleate showed a good results due to the good adsorbtion and coating effection of long alkyl chain of sodium oleate.The hydrophobic lipophilic surface of GO increased in DMF,and the solubility and stability of modified GO in DMF was improved,so a stable concentration of GO in DMF solution 0.5wt%can be obtained.Secondly,preparation and characterization of GO@polyacrylonitrile(PAN)electrospun fibers.The effects of GO with varied particle size(1?m,2?m,5?m)on the PAN electrospun fibers were investigated by using the modified GO with ultra small particle size as the additive.The morphology and structure of electrospun fibers were characterized by scanning electron microscopy(SEM),fiber diameter distribution and optical microscope.The results showed that GO with 1 ?m in diameter and 0.05wt%PAN,0.10wt%GO in DMF can be used to obtain GO@PAN composite electrospun fibers with fiber diameter distribution of 1 00nm?500nm.Preparation and electrochemical properties of RGO@Carbon ultrafine carbon fibers.The GO@PAN composite electrospun fibers were treated by high temperature carbonization and thermal reduction to obtain RGO@Carbon ultrafine carbon fibers.The morphology and electrochemical properties of RGO@Carbon ultrafine fibers were characterized by scanning electron microscopy(SEM),pore structure analysis and XRD.The results showed RGO@Carbon ultrafine fiber has high specific surface area(870 m2/g)and free standing flexible structure.Finally,Supercapacitor prepared base on RGO@Carbon ultrafine fiber as electrode material.The electrochemical performance was characterized by alternative current(AC)impedance analysis,Cyclic Voltammetry analysis and galvanostatic charge discharge analysis.The results show that the RGO@Carbon ultrafine fiber possess high specific capacitance(123.5F·g-1),high power performance(15 kW·kg-1)and long cycle life.