The Preparation, Characteirzation And Capacitive Propetries Of Carbon-based Nanoifbers

Supercapacitor has high power density, long cyclelife and rapid charging/discharging capacity. Thecapacitance mainly depends on pore size, porosity and surface area which can be accessed by electrolyte.Electrospinning can be used to prepare porous carbon nanofiber or carbon composite nanofiberselectrode material, which has high surface area, good conductivity properties, cycle stability and hightemperature resistance and can be used directly as electrode material without adding any binders.PAN-based composite nanofiber was prepared by electrospinng, and then carbon based compositednanofiber was obtained after calcination at high temperature. XRD, SEM, TGA and N2adsorption anddesorption were used to characterize crystal structure, surface morphology, thermal stability and porestructure, respectively. The performance of an electrochemical capacitor can be characterized bygalvanostatic and cyclic voltammetry methods. The detailed contents are as follows:1. C/Cu was obtained from PAN/PVP/Cu(OAc)2nanofibers prepared by electrospinning aftercarbonization process. Box-Benhken design method and Response Surface Analysis were empolyed tooptimize the ratio of the components, which was76:14:10. The highest surface area and pore volume of926m2/g and0.318cm3/g were obtained when C/Cu composite nanofibers were further activated withCO2at800oC for30min. The electrochemical test showed that the capacitance of182F/g (5A/g inKOH,) was obtained which was increased by102%compared with carbon nanofibers.Power density(2530W/Kg) and energy density (12.5Wh/Kg) were about2300%and28%higher than that of carbonnanofibers in BMIMBF4/AC.2. C/Cu/CNTs was obtained from PAN/PVP/Cu(OAc)2nanofibers prepared by electrospinning aftercarbonization process. With the addition of0.5%CNTs, the specific surface area and pore volumereached the maximum of943m2/g and.439cm3/g, respectively. The specific capacitance and energydensity were207F/g and2.6Wh/Kg in KOH, respectively. While the specific capacitance and energydensity were160F/g and16.6Wh/Kg, respectively.3. C/Co and C/Co/CNTs composite nanofibers were prepared by electrospinning and subsequentcarbonization and activation process. The specific surface area and pore volume of771m2/g and0.347m3/g of C/Co/CNTs nanofiber increased by53%and35%, respectively, compared to C/Co nanofiber.The electrochemical test showed that the principle of the C/Co and C/Co/CNTs composite nanofiberelectrode material was electrochemical double-layer capacitor. The specific capacitance and energydensity of C/Co/CNTs electrode material could reach173F/g in KOH at5A/g and8.9Wh/Kg inBMIMBF4/AC, which increased by14%and324%, respectively, compared to C/Co composite electrode.4. C/Ni and C/Ni/CNTs composite nanofibers were prepared by electrospinning and subsequentcarbonization and activation process. The specific surface area and pore volume of705m2/g and0.332m3/g of C/Ni/CNTs nanofibers increased by61%and56%, respectively, compared to C/Ni carbonnanofibers. The electrochemical test showed that C/Ni/CNTs composite nanofiber electrode material showed faradaic effect in KOH. The specific capacitance and energy density of C/Ni/CNTs electrodematerial could reach186F/g in KOH at5A/g and18.2Wh/Kg in BMIMBF4/AC, which increased by37%and16times, respectively, compared to C/Ni composite electrode.