Preparation And Electrochemical Performance Of Novel Supercapacitor Electrode Materials

As a class of noval electrical energy storage devices,supercapacitors have attracted considerable attention due to its high energy and power density,long cycling performance and no pollution during its use.The electrode materials is the key to influence the energy storage performance of supercapacitors.How to improve the electrochemical performance of electrode materials,prepare new high performance electrode materials and simply preparation process as well as reduce the cost of production have become the focus of research.So this paper has involved the following research based on the above background:First,in this paper,we took the self-made carbon nano fibers as precursor material,and it was immersed in the DMF solution of PAN followed by pretreatment process to prepare carbon nanofibers with surface modification.The structure and morphology of the as-prepared material were characterized by XRD,Raman,FTIR and SEM.Surface modification of carbon nano fibers with PAN/DMF concentration of 10 wt%,calcination temperature of 290? and calcination time of 1 hour can achieve a specific capacitance of 127.9 F·g-1 at 0.5 A·g-1,and 17.1%higher than the carbon nanofibers precursors.Besides,this active material can provide 98.5%of its initial capacitance after 5000charge-discharge cycles at 1 A·g-1.Second,the CuS/C composite was synthesized by "one pot" hydrothermal process with Cu?NO₃?₂·3H₂O as copper source,thiourea as sulfur source,D-sodium gluconate as complexing agent and deionized water as solvent.The chemical composition and microstructure of the as-prepared material were characterized by XRD,Raman,FTIR,SEM and EDS.The CuS microspheres with dimeter of 1?2?m were a large majority of the final product,which distributed with a large number of petaloid folds with average width of 50nm on their surface.There were also a small amount of carbon microspheres with smooth surface?about 6 wt%?.The CuS/C composite that obtained with hydrothermal conditions of 150?and 24 h exhibited perfect supercapacities.Typically,its specific capacitance was 719.6 F·g-1?1 A·g-1?,decreasing only 20%of the maximumcapacitance after 1000 cycles.Next,the nickel foam was used as matrix material,and its pores were filled by lots of carbon submicrospheres through hydrothermal method.Thus they can greatly improve the specific area of substrate material.In the next hydrothermal process,Ni₃S₂ nanoparticles were grown on carbon microspheres by using NiCl₂·6H₂O as nickel source,thiourea as sulfur source.And eventually we got the nickel foam@carbon micro sphere s@ni ckel sulfide?NF@CMSs@Ni₃S₂?composite.The material composition and surface morphology of as-prepared composite werestudied by XRD,Raman,SEM,EDS and TEM.The area capacitance of the composite electrode was 7.10 F·cm-2 at 0.008 A·cm-2,54%capacitance retention can be realized when the current density increased to 0.056 A cm-2,and only 19%capacitance attenuation even after 2500 cycles.Finally,the nickel foam was filled by copper powders through ultrasonic process followed by immersion reaction to get nickel foam based CuS?NF@CuS?composite.The interconnected CuS nanosheets with hexagonal system structure were filled in the nickel foam,and their thickness was about 0.2 ?m.The NF@CuS composite showed a high area capacitance?11.4 F·cm-2 at current density of 0.090 A·cm-2?and excellent cycle stability?85.0%capacitance retention after 3000 cycles?.