Electrospinning Synthesis Of Tin-and Antimony-based Anode Materials And Their Electrochemical Performance

Rechargeable Lithium-ion batteries（LIBs）have been widely used in portable electronic devices,hybrid electric vehicles and battery electric vehicle.However,the current traditional graphitized carbon anode materials could not satisfy the demands for the new-generation Li-ion batteries with high energy density and high power because of low theoretical capacity(372 mAh g^-1)and poor rate performance.Sn or Sb-based materials have been studied intensively as the promising next-generation anode materials,because they have a relatively high lithium storage capacity.Nevertheless,these materials have large volume changes during discharge–charge processes,leading to cracks and pulverization of electrodes and thus the poor cycle life.In this dissertation,the composites of tin,or antimony alloys encapsulated in carbon nanofibers as anode materials for lithium ion batteries were prepared by high energy ball milling,electrospinning and heat treatment.The electrochemical performance of tin and antimony based materials have been improved by optimizing the particle size,alloying and carbon coating.SnSe powder as the active material,PAN as carbon source,SnSe@CNFs composites with 1D nanostructures were synthesized using a single nozzle electrospinning method and heat treatment method.The lithium storage capacity of SnSe@CNFs decays slowly,the electrode still delivered a discharge capacity of 730 mAh g^-1 for the 100 th cycle.In the rate performance test,the SnSe@CNFs delivered a specific capacity of 590 mAh g^-1 at current density of 1800 m A g^-1.Moreover,the recoverable capacity is 95% when the current density turns back to 100 mA g^-1.The electrode shows a good rate capability.The pure SnSe without CNFs encapsulation shows a poor cycle life（only to maintain the 30 cycles）.Se doped SnS_0.9Se_0.1 powders were prepared by cold pressing,sealing tube calcination,ball milling and so on.Se doped SnS@CNFs composites（PVP as carbon source）were synthesized using a single nozzle electrospinning method and heat treatment method.The lithium storage capacity of SnS_0.9Se_0.1@CNFs reached 700 mAh g^-1 for the 100 th cycle,the recoverable capacity is 94% when the current density turns back to 200 mA g^-1.By contrast,the samples of SnS@CNFs reached 530 mAh g^-1 and 89%,respectively.Sb₂Se₃ powders were prepared from ball milling.The Sb₂Se₃@CNFs composites（PVP as carbon source）were synthesized using a single nozzle electrospinning method and followed heat treatment method.The lithium storage capacity of Sb₂Se₃@CNFs decays slowly,the electrode still delivered a discharge capacity of 616 mAh g^-1 for the 200 th cycle.In the rate performance test,the Sb₂Se₃@CNFs delivered a specific capacity of 457 mAh g^-1 at current density of 3600 mA g^-1.Moreover,the recoverable capacity is 91% when the current density turns back to 200 mA g^-1.The capacities for various current densities are similar,indicating an excellent rate performance.