Synthesis,Modification And Electrochemical Properties Of Mo And Ni Sulfide Nanostructures

As important components of metal sulfides,molybdenum sulfide and nickel sulfide as electrode materials not only have high theoretical capacity and voltage platform,but also have wide sources and low cost.They are powerful candidates for the next generation of lithium-ion battery anode materials.However,these two metal sulfide electrode materials have problems such as low ion/electron conductivity and volume expansion and pulverization.In this paper,it was ameliorated by reducing particle size,controling morphology and carbon modification.In this paper,an electrode material composed of irregular MoS2 nanoparticles was synthesized by simple wet chemical method.The effects of heat treatment temperature and reactant mass ratio to the morphology and electrochemical properties of the experimental products were investigated.Under the optimal experimental conditions,the optimized MoS2 not only has a larger interlayer spacing(0.92 nm)than bulk MoS2,but also has similar structure of the 3D network.The material of this structure not only can alleviate the volume expansion problem of the electrode material,but also can increase the contact area between the anode material and the electrolyte,and greatly improve the electrochemical performance of the battery.At a current density of 0.1 A g-1,the reversible cycle capacity of the material gradually increases and remains stable.The reversible capacity is increased from the initial 927 mAh g-1 to 1031 mAh g-1 after 100 cycles,and the rate performance is also excellent.When MoS2 was modified with porous carbon,MoS2 with an interlayer distance of 8.8 nm successfully grew on the porous carbon.This carbon-modified electrode material has stable electrochemical cycling performance.After 80 cycles of constant current charging and discharging at a current density of 0.1 A g-1,the capacity retention rate of the battery is as high as 90%or more,and the rate performance is also excellent.In this paper,two different morphologies of nickel sulfide,micron-sized hollow spherical Ni3S2 and lamellar NiS were prepared by adjusting the type of reducing agent by the same wet chemical method,and their electrochemical cycle performance was poor.In order to improve their electrochemical performance,the graphene oxide was selected and successfully compounded to the nickel sulfide.After modification,the nano-sized Ni3S2 with a size distribution of about 20-40 nm is uniformly grown on the graphene.The nano-scale nickel sulfide greatly increases the reactive sites,and the elastic graphene increases the conductivity while also buffering the volume expansion caused by the nickel sulfide material during the deintercalation of lithium.Therefore,the carbon modified product has better excellent electrochemical properties than the micron-sized hollow spherical NiS and lamellar Ni3S2.At the current density of 0.1 A g-1,the reversible capacity of the first circle is 542 mAh g-1,and the reversible capacity is still as high as 509 mAh g-1 after 100 cycles.