Fabrication Of Functional Carbon/ Molybdenum Disulfide Composites And Study On The Properties Of Lithium Ion Battery

Lithium ion battery(LIBs)is playing increasing important roles in energy field,which has become an integral part of contemporary life.It has been great attention due to their advantages of high operating voltage,long cycle life and excellent safety,etc.Nowadays,the limited specific capacity of graphite cannot meet the requirements of LIBs.Therefore,a critical challenge for further boosting their performance is to design and synthesize novel electrode materials with excellent electrochemical propertiesMolybdenum disulfide(Mo S2),a typical transition metal dichalcogenide with unique sandwich structure,has shown potential applications in many fields.Compared with graphite materials,molybdenum disulfide delivers a higher Li-ion storage specific capacity(670 m Ah g-1).However,as semiconductor material,because of low conductivity and the enormous volume expansion during charge-discharge processes,unmodified Mo S2 materials exhibits poor performance in LIBs.In this paper,we demonstrate a novel nanostructure of carbon materials,which have excellent mechanical strength and good electrical conductivity etc.By combines the advantage of high theoretical capacity of transition metal sulfides,not only alleviating they stack and volume expansion in the process of charging/discharging,but also improving their electrochemical performance of materials,shows the value of its application.The main contents are as follows: 1.Through the hard template method,we have prepared the nitrogen/sulfur-doped porous carbon nanosheets,the prepared porous carbon nanosheets have high specific surface area and rich pore structure,and the high content of nitrogen atom and sulfur atom(4.96% and 3.01%)As the anode material in LIBs under the current density of 0.1 A g-1,the reversible capacity of the porous carbon nanosheets is obout 925 m Ah g-1,showing excellent cyclic stability and good rate performance.When the cycling of the electrode was continued to 250 cycles,a capacity of the material remained in the 920 m Ah g-1.On this basis,the composite of porous carbon nanosheets and Mo S2(NSCN@Mo S2)composite was prepared by hydrothermal method,and the reversible capacity of NSCN@Mo S2 composite was 818 m Ah g-1 at the current density of 0.1 A g-1,as well as excellent cyclic stability performance in lithium storage.2.Through the use of metal nitrate supplemented carbonization process,by using polyethylene pyrrolidone as a carbon source,three-dimensional porous graphite carbon material is prepared.Subsequently,three-dimensional porous graphite carbon@Mo S2 composite is synthesized by hydrothermal method.The composite exhibits excellent electrochemical performance,the reversible capacity is maintained at 1088 m Ah g-1 under the current density of 0.1 A g-1,which indicates that the three-dimensional structure framework effectively buffers volume expansion and suppresses the collapse phenomenon of Mo S2,the three-dimensional porous graphite carbon@Mo S2 composite shows excellent cyclic stability and good rate performance.3.Through the use of carbonized cotton cloth as a flexible material,the carbon cloth/graphite carbon@Mo S2 composite material was prepared by combined with the high-temperature carbonation and hydrothermal method.The porous graphite carbon sheets are vertically grown on the surface of the carbon cloth,which can effectively support Mo S2 nanosheets and form a three-dimensional porous network structure.As a anode materials in LIBs,the as-prepared electrode exhibits a high reversible capacity of 1091 m Ah g-1 high initial Coulombic efficiency(68.6%)at 0.1 A g-1,good rate capability,and long cycling stability in LIBs.