Synthesis And Lithium-ion Battery Performance Of FeS/Fe₂O₃/CNT Composite Films

Transition metal sulfide has become one of the research hotspots owing to its high capacity.However,cycling performance of the transition metal sulfide needs to be improved because of the poor conductivity,large volume effect and the instability of SEI film.In this paper,the electrode material structure is designed from the perspective of improving metal sulfide conductivity and cycle stability.On the one hand,increasing the porosity will improve the volume expansion during charging and discharging.On the other hand,combining carbon nanotubes with transition metal oxides of good conductivity and high specific capacity could improve the conductivity of the electrode material and obtain composite film as an electrode materialis for lithium ion batteries?LIBs?.In this paper,a simple hot solvent method is used to obtain the prescursor of ferrous sulfide,and heating at a predetermined temperature causes the Fe S to be partially oxidized,obtaining core-shell micro flowers.In order to obtain ideal anode materials for LIBs,this paper adopts two different methods to obtain flexible Fe S/Fe₂O₃/CNT composite films,the main research contents and results are as follow:One approach to produce Fe S@Fe₂O₃/CNT composite films is oxidation followed by compounding.The steps are as follows:first,the core-shell structure of the Fe S@Fe₂O₃ composite is obtained by hydrothermal method and calcination,then by an immersing and rolling method,the Fe S@Fe₂O₃ composite of different concentration and highly conductive CNTs are compounded to obtain flexible Fe S@Fe₂O₃/CNT composite.On the one hand,the composite electrode can alleviate the damage to the material structure caused by the volume changed of particles,On the other hand,it can greatly improve the conductivity and electrochemical stablity of the material.In addition,the composite film can be directly used as electrode material without any binder and additive in the process of battery preparation,showing high specefic capacity.When the composite material is used as anode material of LIBs,when the loading in the right concentration,it shows good lithium storage performance with the reversible capacity up to 960 m Ah/g after 100 cycles at the current density 0.2 A/g and stable cycling performance with the discharge capacity up to 440 m Ah/g after 600 cycles at the current density 2 A/g.Additionally,the Fe S/Fe₂O₃/CNT composite films were synthesized by compounding followed by oxidation.The steps are as follows:Fe S precursor obtained by hydrothermal method,and compounded with CNT by an immersing and rolling method to obtain Fe S/CNT composite films,then calcined at predefined temperature.the high-loading Fe S/Fe₂O₃/CNT composite films were obtained.During this period,the Fe S precursor is partially oxidized to form a core-shell Fe S@Fe₂O₃ composite.It is worth noting that more defects and amorphous carbon will be burned by annealing,at the same time,the spherical Fe particles?impurity catalyst?in the CNTs are oxidized to generate Fe₂O₃ nanoparticles,which greatly improves the lithium performance of the material.When evaluated as anode materials for LIBs,the Fe S/Fe₂O₃/CNT composite film exihibits a discharge capacity of 1720 m Ah/g after100 cycles at 0.2 A/g,and the specific capacity of the composite obtained is obviously increased.