Preparation,Modification And Electrochemical Energy Storage Performance Of PVP-based Electrospun Carbon Nanofibers

In recent years,supercapacitors have attracted wide attention in various neighborhoods due to their high power density,good cycle stability and environmental protection.Electrode material is the key to the energy storage property of supercapacitors.How to prepare high energy density and power density electrodes has become a major problem.Electrospun carbon nanofibers have high aspect ratio and three-dimensional network structure between nanofibers,which make them an ideal self-supporting flexible electrode material.At the same time,electrospun carbon nanofibers are also an ideal substrate material which can be easily compounded with other pseudocapacitive materials to prepare high performance electrodes.In this paper,a series of studies are carried out as follows:(1)Controllable and efficient nitridation of PVP-based electrospun carbon nanofibers was achieved by pyrolysis of g-C3N4.Carbon nanofibers with high nitrogen content were successfully prepared,and the nitrogen content was 8.96%.Nitrogen-doped carbon fibers exhibit good electrochemical properties in the three-level test system.The specific capacitance of NC-800 is 264 F/g when the current density is 1A/g.In the process of electrochemical energy storage,nitrogen doping increases the pseudocapacitance and energy density of carbon nanofibers,and the lone pair electrons of nitrogen combine with hydrogen ions in water to form hydrogen bonds.The wettability of the electrode was improved and the contact resistance of the system was reduced.Nitrogen content in carbon nanofibers was effectively regulated by controlling nitriding temperature.(2)Porous carbon nanofibers were prepared by blending tetraethyl orthosilicate with the precursor solution of PVP-based carbon nanofibers after carbonization and acid treatment,which greatly increased the specific surface area of carbon nanofibers.The specific surface area of pure carbon fibers(CNFs)was 150.8767 m~2/g,while that of porous carbon fibers(PCNFs-2)was 353.6557 m~2/g.At the same time,porous carbon nanofibers exhibit good electrochemical properties.When the current density is 1A/g,the specific capacitance is 153F/g.The multi-stage pore structure reduces the resistance and has a good ratio.The macroporous structure provides channels for ion transport in electrodes.Microporous structures are directly involved in charge storage.The multi-stage structure coordinates with each other and improves the electrochemical performance of carbon fibers.On this basis,nitrogen-doped porous carbon fibers were prepared by further nitriding treatment.Nitrogen-doped carbon fibers improved the energy density of carbon materials,but its ratio was relatively low.Pore structure just made up for this shortcoming.