Preparation And Properties Of Molybdenum Disulfide Based Cathode Materials For Lithium Sulfur Battery

Lithium sulfur battery has high theoretical specific energy?2600Wh/kg?,which is 3-5 times of the current commercial lithium-ion battery,and it is more practical than lithium air battery.However,there are still some problems such as poor conductivity and shuttle effect,which hinder its commercialization.MoS₂ is a typical layeredtransition metal compound,containing metal sulfur bond,which can be combined with polysulfide through electrostatic or chemical bond.MoS₂ can fix polysulfide group to prevent its dissolution,so as to inhibit shuttle effect.Therefore,the combination of MoS₂ and carbon materials as cathode materials of lithium sulfur battery can not only improve the conductivity,but also play the role of controlling polysulfide.In this paper,graphene like two-dimensional layered MoS₂ and three-dimensional honeycomb MoS₂ nanomaterials were applied to the cathode materials of lithium sulfur battery.The pomegranate like sulfur/carbon black/MoS₂ composite and honeycomb like sulfur/carbon black/MoS₂ composite were successfully prepared by ball milling,traditional hydrothermal method and tubular furnace method,respectively.The microstructure and crystal structure of the samples were characterized by SEM and XRD.The electrochemical properties of the materials were studied by charge discharge test and cyclic voltammetry test.The effects of different components and morphology on the electrochemical properties were discussed.?1?Carbon black particles with uniform size about 50nm were dispersed in sulfur by ball milling and hydrothermal methods,forming composite material with sulfur acts as the matrix and carbon black acts as the conductive framework,and obtaining the best preparation technology of sulfur/carbon black composite with good dispersion.?2?Sulfur/carbon black composite materials with different proportion were prepared by changing the proportion of carbon black?the mass ratio of carbon black is 0%,20%and 40%respectively?.The electrochemical performance were studied to obtain the best proportion of sulfur/carbon black composite materials as the positive active materials of lithium sulfur battery.?3?The thin layer MoS₂ nanomaterials were prepared by intercalation blasting,and the sulfur/carbon black composite materials were compounded with the thin layer MoS₂to prepare the pomegranate like sulfur/carbon black/MoS₂ composite materials by hydrothermal method.The pomegranate like structure takes carbon black as the conductive framework,and the MoS₂sheet forms a barrier to polysulfide shuttle,which can effectively improve the electrochemical performance of the materials when applied to the cathode materials of lithium sulfur battery.?4?The honeycomb MoS₂ porous material was prepared by hydrothermal method,and the honeycomb sulfur/carbon black/MoS₂composite was prepared by tube furnace sintering.As the active material of lithium sulfur battery,MoS₂ can not only combine with polysulfide through electrostatic action or chemical bond,but also fix polysulfide group by its own honeycomb like porous structure to inhibit the shuttle effect.