Preparation And Electrochemical Performance Of Mo-based Sulfide Anode Materials For Lithium/sodium Ion Batteries

Lithium ion batteries(LIBs)have been extensively applied in human life for electric vehicles and portable electronics owing to their environmental friendliness,high specific capacity and long cycling life.Since sodium element is abundant,widely distributed and low cost,sodium ion batteries(SIBs)are considered as promising alternative for LIBs.Therefore,great efforts should be amied at exploring appropriate anode materials for both LIBs and SIBs.Layered transition-metal dichalcogenides have been widely studied as anode materials because of unique physical properties and high theoretical capacity.However,the application of MoS2 anodes suffer from several problems such as low electrical conductivity and poor stabillity.Herein,with the help of nanostructure desigining,combining with conductive carbonaceous materials and phase transformation,we reported molybdenum disulfide(MoS2)and molybdenum diselenide(MoSe2)based material to explore and improve their electrochemical performance.as anode materials.The main contents and results of research are as follows:(1)The carbon coated MoS2 microspheres(MoS2/C)have been synthesized by solvothermal and post carbonization method using MoO3 nanorods and thioacetamide powder as the Mo and S sources.Self-assembled MoS2 nanosheets are intimately combined with a carbon layer to form MoS2/C composite microspheres.The core-shell microsphere heterostructure enhances electrical conductivity and good structural stability.The MoS2/C electrode delivers an initial discharge capacity of 1205 mAh g-1 and still maintains 902 mAh g-1 after 200 cycles at a current density of 100 mA g-1 and higher than 99%coulomb efficiency.(2)We design hollow 1T MoS2 arrays on carbon cloth(1T-MoS2/CC)via a facile solvothermal method.MoO3 arrays on carbon cloth obtained by a seed-assisted hydrothermal method not only serve as a Mo source,but also play an important role as the hollow structure template.This hollow and array structure has more surface area,improve electron transport and ion diffusion and absorb the volume change to enhance the structure stability.The obtained electrode displays excellent sodium ion storge performance(a high specific capacity of 576 mAh g-1 after 200 cycles at 200 mA g-1 and enhanced rate performance of 276 mAh g-1 at 2 A g-1).(3)N-C layer modified MoSe2 composite(MoSe2/N-C)has been constructed via hydrothermal plus thermal polymerization.The MoSe2 microspheres are composed of interconnected thin nanoflakes and uniformly wrapped by self-polymerizing N-C layer.The MoSe2/N-C electrode exhibits an initial dischage capacity of 904 mAh g-1 and a high specific capacity of 698 mAh g-1 after 100 cycles at 100 mA g-1.In addition,the lithium ion storage mechanism of MoSe2 is investigated by ex-situ XRD technology.