Synthesis And Investigation Of Iron Disulfide@ Carbon Fibers As Cathode For Lithium Sulfur Batteries By Electrospinning

Lithium-sulfur batteries have attracted great attention during the past few decades,as the energy density of lithium-sulfur batteries is several times higher than that of traditional lithium-ion batteries.Besides,lithium-sulfur batteries are low-cost and environmentally friendly.However,the commercial application of lithium-sulfur batteries is hindered by the dissolution and the shuttle phenomenon of polysulfides,the poor conductivity of sulfur.To overcome these drawbacks,scientists have proposed various methods,such as optimizing the electrolytes,synthesizing composite electrode of sulfur/carbon,sulfur/polymer,sulfur/metal organic framework（MOF）,and constructing novel structure of batteries.In addition,there are other ways to improve the performance of lithium-sulfur batteries,such as using appropriate charge and discharge conditions,heteroatom doping atoms into sulfur molecules,and adopting different kinds of electrolytes and binders.In this paper,the composite of transition metal sulfides and polymers as cathode materials for lithium sulfur batteries was studied.FeS₂@carbon fibers composites with pore structure were prepared by electrospinning.This electrode materials are composed of three-dimensional interconnected porous carbon fibers,which are beneficial to the diffusion of electrons and ions.FeS₂ nanoparticles are distributed in the inner wall of carbon fibers,which can prevent the dissolution of polysulfides during the electrochemical reactions.The effects of different proportions of FeS₂ on the morphology,structure and electrochemical properties of the composites were studied.The structure,morphology and electrochemical properties were characterized by XRD,SEM,TEM,XPS and Raman,CV and EIS.The experimental results show that FeS₂@carbon fiber nanocomposites have been successfully prepared.The surface of the fibers is smooth and FeS₂ particles can be firmly loaded on the inner wall of carbon fibers.The electrochemical tests show that the electrochemical performance is the best when the ratio of FeS₂ is 30%.When the current density at 20 mA g^-1,the first discharge capacity of 752 mAh g^-1 is obtained,and the capacity is maintained at 448 m Ah g^-1 after 100 cycles,which shows excellent rate performance.