Preparation Of Porous Carbon Nanofibers By Electrospinning For Improvement Lithium(Sodium) Storage

With the rapid development of society,people's demand for green energy is increasing.In order to reduce the excessive consumption of fossil fuels and promote the rapid growth of electric vehicles and electronic equipment,people are vigorously promoting the development of high-energy rechargeable batteries.Lithium-ion batteries have been widely used due to their good cycle performance,high energy density,and environmental protection.Sodium-ion batteries have received more and more attention due to their potential cost advantages and abundant natural resources.Traditional graphite anode materials can't meet the current demand.SnSb alloy is considered to be a promising anode material due to its relatively high theoretical capacity.Moreover,both Sn and Sb have the ability to store lithium-ion and sodium-ion during charge and discharge process,which helps to increase the overall capacity.In this paper,porous carbon nanofibers coated SnSb alloy nanoparticles were prepared by electrospinning technology,and their electrochemical properties were studied.The main research contents are as follows:1.SnSb@N-PCNFs were synthesized by electrospinning and subsequent heat treatment.Using lithium azide as punching agent and nitrogen source,SnSb@N-PCNFs with uniform pore size distribution were obtained.The average diameter of fibers was about 200 nm,and the diameter of SnSb alloy particles was 12-20 nm.Porous nanofiber can effectively alleviate the problems of volume expansion and particle pulverization during charging and discharging,and greatly improve the cycle stability and rate performance of the lithium-ion battery.At a current density of 100 mA g-1,the capacity was maintained at 892 mA h g-1 over 100 cycles.At a high current density of 2000 mA g-1,the capacity remained at 487 mA h g-1 after 1000 cycles.2.The SnSb@N-PCNFs was further modified by coaxial electrospinning.rGO/C was coated on the surface of SnSb@N-PCNFs,and rGO@SnSb@N-PCNFs was synthesized and applied to the anode electrode of Sodium-ion batteries.A series of electrochemical performance tests showed that rGO@SnSb@N-PCNFs electrode material had good reversibility and capacity retention.It is indicated that the introduction of rGO provides an effective electron conduction path for SnSb active materials,which greatly improves the cycle stability and rate performance of SnSb-based active materials as anode materials for Sodium-ion batteries.At a high current density of 2000 mA g-1,after 1000 cycles,the reversible capacity of the rGO@SnSb@N-PCNFs electrode material can still be maintained at 300 mA h g-1,and the coulomb efficiency is close to 100%.