The Synthesis Of FeS₂/carbon Composite Electrode And Its Electrochemical Properties Application On Sodium-ion Batteries

As a new battery system,Sodium-ion batteries?NIBs?have attracted more and more attention because of its rich resources and high safety.At present,the performance of NIBs can not meet the application requirements due to the lack of theme materials for storing sodium ions.Recently,FeS₂ has been considered a potential NIBs cathode material due to its abundant resources,low cost,environmental friendly nature,and high theoretical capacity,which become a hot research topic.However,the huge volume changes of FeS₂ during charge/discharge processes and poor conductivity have hindered its practical application.In order to address these problems,we designed and synthesized FeS₂/carbon nanocomposite cathode materials,which demonstrate an excellent performance in NIBs.The research work includes the following aspects:Firstly,Fe₃O₄@C precursor was prepared by hydrothermal method,and then FeS₂@C composite was obtained by sulfidation at high temperature.The FeS₂ nanoparticles are coated with a thin layer of amorphous carbon,which not only improves the conductivity but also efficiently alleviates the stress induced by the volume change during charge/discharge processes,which greatly improved the electrochemical performance of NIBs.As a result,it delivered initial discharge capacity about 410 mA h/g at 50 mA/g and retained 294 mA h/g after 110 cycles;even tested at a high current density about 2000 mA/g,the discharge capacity was still about 165 mA h/g,which exhibited excellent performance among the same systems.Then,FeS₂ anchoring on ordered mesoporous carbon was synthesized through a solution precipitation method.FeS₂ nanoparticles are deposited on the rough surface of CMK-3 and CMK-3 retains an ordered porous structure.The rough surface of CMK-3 can help to storage more nanoparticles and the ordered porous structure also provide additional sodium ion transport channels.This material showed an excellent sodium storage properties.The designed FeS₂/CMK-3 electrode is able to deliver a high discharge capacity of 229 mA h/g even after 500 cycles at a current density of 1000 mA/g.It retains a high specific capacity of 172 mA h/g even at 4000 mA/g.It showed that FeS₂/CMK-3 composite is a promising cathode material for NIBs.In this paper,different carbon/FeS₂ composites were developed as cathode materials for NIBs.Their structures and components were characterized using X-ray powder diffraction?XRD?,field emission scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and thermogravimetric analysis?TGA?.And the electrochemical performance measurements proved their high sodium storage behavior.The results showed that the introduction of carbon is an efficiently approach to enhance the performance of FeS₂ cathodes in NIBs as a result of high conductivity and good mechanical property,which could provide the basis for the development of high performance of Sodium-ion batteries.