Study On Construction Of One-Dimensional Nanocomposite Materials By Electrospinning And Their Electrochemical Performance

With the development of human civilization,many problems have to be solved,such as environmental pollution and energy crisis.Faced with the above problems,advanced energy technologies need to be developed to achieve green energy.In the field of energy conversion and energy storage systems,there is a general consensus that one-dimensional nanomaterials(including nanowires,nanorods,nanotubes,etc.)show high specific surface area,large porosity and great long diameter,being considered as one kind of the most ideal materials.Since its first discovery in 1934,electrospinning technique has aroused widespread concern and in-depth study.At present,electrospinning is used as one of the most effective methods for preparing nanofibers with mass continuous processing.Compared with other methods of preparing one-dimensional nanomaterials,this method has the advantages of simple operation equipment,low spinning cost,wide variety of spunbond fibers and controllable fiber morphology.The one-dimensional nanomaterials prepared by this method have large specific surface area,high porosity and large aspect ratio.By adding functional components to combine the advantages of one-dimensional nanomaterials and functional components,the preparation of one-dimensional nano hybrid materials has broad application prospects in many fields.In this thesis,one-dimensional nanomaterials were prepared by electrospinning technique.They were prepared by the addition of inorganic components.After pretreatment,pre-oxidation,high temperature carbonation,and medium temperature phosphating,functionalized onedimensional nanocomposite materials have been successfully achieved to explore their applications in the fields of electrochemical catalytic hydrogen evolution catalysts and lithium ion battery anode materials.This thesis is divided into two parts.First,one-dimensional nanohybrid material of Co@ polyvinylpyrrolidone(PVP)was prepared by electrospinning.Then,Co3O4 and sodium hypophosphite(NaHPO2)were mixed at a ratio of 1:8,and heated at 550 °C for 2 h to obtain one-dimensional hollow nanohybrid material.The medium temperature phosphating process was protected under Ar at 300 °C,2 h.Thus,one-dimensional CoP nanotubes are successfully prepared.To achieve the current density of 10 mA cm-2,only the overpotential of-152 mV is needed,which indicates that the catalytic efficiency is high and the energy conversion effect is good.The catalytic activity after 10 h was almost unchanged,indicating that the catalytic stability of the material was good.Second,polymethylmethacrylate(PMMA)and PVP were mixed and prepared by electrospinning to successfully obtain one-dimensional nanocomposite fibers.The nanosized silicon(Si)particles were mixed with PMMA and polyvinylpyrrolidone(PVP).The electrospinning process is unique in that the aluminum foil is replaced with water and then polymerized with pyrrole in an aqueous solution at 0-2 °C.The material was dried and calcined at 850 °C for 2 h under inert gas to successfully prepare one-dimensional Si/C nanocomposite with porous structure.It is assembled into a half-cell to test the electrochemical performance.When the current is finally rechanged from 2 A g-1 to the original 0.1 A g-1 after 100 cycles of charge/discharge cycles,its capacity is still 910 mA h g-1,keeping a 100% retention of the initial capacity.Moreover,when the battery undergoes 200 cycles at a current density of 1 A g-1,it still keeps a high capacity of 515 mA h g-1,which accounts for 74% of the intinial capacity(697 mA h g-1),indicating that the Si@NC has excellent cycling performance as lithium ion battery anode materials.