One-Dimensional Electrospun Fibers Containing Metal Organic Framework And Their Application In Li-ion Batteries

In this paper,electrospinning technology is used to assemble metal-organic frameworks?MOF?nanoparticles and prepare electrospinning nanofibers with uniform and controllable size and a large number of MOF particles.After a series of post-treatment,one-dimensional semiconductor nanocomposites coated with sulfide nanosheets or embedded with transition metal/metal carbides were obtained.The samples were used as anode materials for lithium ion batteries.The effects of the structure and composition of the materials on the electrochemical properties of Li-ion battery were investigated.MOF-based carbon nanocomposites with high lithium electrical properties were prepared.The main contents of this paper are as follows:1.MoS₂/N doped porous carbon nanofibers with high Li-ion battery properties were prepared.Firstly,by using electrospinning technology to assemble nanostructured units,ZIF-8 nanoparticles were tightly assembled in PAN electrospun fibers through direct spinning of polyacrylonitrile?PAN?and zeolite-structured MOF?ZIF-8?.This structure is conducive to improving the pore volume and specific surface area of the materials.Then,N-doped porous carbon nanofibers?PCNFs?were obtained by high temperature annealing in nitrogen atmosphere.Finally,MoS₂ nanosheets were coated on PCNF surface?PCNF@MoS₂?by hydrothermal method using ammonium molybdate and thiourea as precursors of MoS₂.The prepared composite material has the following advantages:firstly,the composite of carbon material and MoS₂ effectively solves the shortcomings of poor conductivity and low stability of semiconductor material MoS₂;secondly,carbon fibers as templates can make MoS₂ nanosheets vertically assembled on the surface of the fiber while directionally growing and assembling into a one-dimensional structure,which solves the dispersion problem of MoS₂ well;Porous structure is conducive to solving the problem of volume expansion during lithization,and high specific surface area is conducive to full contact between electrolyte and active material,thus improving the cycle stability and lithium storage performance of battery.The results show that the specific capacity of PCNF@MoS₂ after 450 cycles at 1.0 A g^-1is 1116 mA h g^-1,which proves the high cycle stability and high capacity of PCNF@MoS₂.2.The performance of lithium-ion batteries doped with transition metal carbides and porous carbon fibers is also studied in this paper.Nitrogen-doped carbon fibers containing Fe₃C nanoparticles?N-Fe₃C-CNFs?were prepared by electrospinning and calcination of MIL-88 nanoparticles.The material was characterized by a series of microstructures and components.The material was used as negative electrode material for lithium ion batteries to study the electrochemical performance of lithium ion batteries,including cycle,rate,cyclic voltammetry?CV?and electrochemical impedance spectroscopy?EIS?performance.The results show that the material maintains a reversible specific capacity of 756.6 mA h g^-1 after 200 cycles at 1 A g^-1 current density.