Structure And Electrochemical Properties Of Molybdenum Vanadium Sulfide Carbon Composites

Lithium ion batteries have been widely used in portable electronic devices and electric vehicles.However,the demand for fast charging and durability of electronic devices and the improvement of battery endurance of electric vehicles have raised higher requirements for the electrode material performance of lithium ion batteries.In recent years,transition metal sulfide has attracted much attention due to its high capacity and special physical and chemical properties,especially the electrode materials of molybdenum sulfide or vanadium sulfide.In this paper,molybdenum-vanadium sulfide with special morphology and its composites(loaded on gelatin-based carbon)were prepared by different solvent-thermal methods from organic complexes containing molybdenum and vanadium respectively,and their electrochemical properties as anode materials for lithium ion batteries were studied.The details are as follows:(1)Using organic complexes containing molybdenum and vanadium respectively as raw materials,assisted by soft template,the molybdenum-vanadium sulfide was synthesized by two-step solvent-thermal method(precursor preparation and sulfurization).The effects of different proportion of precursor,sulfurization temperature,sulfurization time and dosage of sulfurization agent(thioacetamide)on lithium storage performance of molybdenum-vanadium sulfide were investigated.Among them,the sample whose precursor with a ratio of 1:1 of raw materials reacted with thioacetamide at 200? for 9 h,showed the optimal specific capacity and multiplier performance as anode material for lithium ion battery(the discharge capacity of the first cycle reached 1432.40 mAh g-1 at the current density of 0.1 A g-1).(2)Organic complexes containing molybdenum and vanadium respectively were used as raw materials to directly react with thioacetamide to synthesize molybdenum vanadium sulfide in one-step hydrothermal method.At the same reaction temperature,the sample synthesized by 12 h was used as the negative electrode of the lithium ion battery.At the current density of 0.1 A g-1,its discharge capacity of the first cycle could reach 1519.80 mAh g-1,and the coulomb efficiency was 73.25%,but the capacity attenuation was serious.(3)With biomass gelatin as raw material and nickel nitrate hexahydrate as salt template,the gelatine-based carbon was prepared by freeze-drying and carbonization,and the molybdenum-vanadium sulfide was loaded on this gelatine-based carbon material to improve the problem of rapid capacity attenuation and cycle stability.