| Lithium ion batteries have high energy density,long life and environmental friendliness,which have been widely used in mobile electronic devices,electric vehicles and new energy applications.The electrode material of lithium ion battery has an important influence on its performance.Although the graphite anode material of commercial lithium ion batteries has stable cycle performance,its low theoretical specific capacity limits the development of high-performance lithium ion batteries Therefore,developing an anode material with high electrochemical lithium storage capacity,long cycle stability and high rate performance is of great significance for high-performance lithium ion batteriesThe metal sulfide with layered structure becomes a potential anode electrode material due to its high specific capacity.However,the poor electrical conductivity of metal sulfides and rapid decay of capacity steming from volume changes during lithium intercalation/delithiation limits their practical application.The combination of layered metal sulfide and conductive carbon materials(such as graphene,carbon nanotubes)not only improve reversible specific capacity,but also significantly enhance cycle stability and high rate characteristics.Graphene with excellent electronic conductivity,large specific surface area,and good flexibility has been extensively studied.However,many studies have focused on the combination of single layered metal sulfides and carbon materials.There are relatively few studies on the combination of two or more layered metal sulfides with carbon materials.Compared with a single metal sulfide,two or more metal sulfides have more redox couples and various heterostructures,indicating better electrochemical lithium storage performance.The main work synthesized MoS2-Bi2S3/graphene(MoS2-Bi2S3/rGO)and MoS2-Sb2S3/graphene(MoS2-Sb2S3/rGO)composites by hydrothermal method,as well characterized and studied their morphology,microstructure and electrochemical lithium storage performanceThe MoS2-Bi2S3/rGO composites were synthesized by hydrothermal method using sodium molybdate,lanthanum nitrate,L-cysteine and graphene oxide(GO)as raw materials.We characterized the structure and morphology of the samples by XRD,SEM,TEM and XPS,and also investigated their lithium storage properties.Especially,when the Mo and Bi molar ratio is 4,MoS2-Bi2S3/rGO-2 composite exhibits a honeycomb-like structure,and the interlaced MoS2 nanosheets and Bi2S3 particles are evenly distributed on the curled graphene sheets.Many breaks and few layer MoS2 nanosheets in the HRTEM image exposed a large number of active sites.MoS2-Bi2S3/rGO-2 composite exhibits excellent lithium storage capacity.At a current density of 100 mA g-1,the reversible specific capacity is as high as 1140 mA h g-1,and the coulombic efficiency is 78.4%.In addition,the reversible specific capacity reached 886 mA h g-1 at a high current density of 1000 mA g-1,and maintained 811 mA h g-1 after 1000 cycles,indicating its excellent cycle and rate characteristics.The enhancement of electrochemical performance is due to the small Bi2S3 particles and the few layer MoS2 nanosheets dispersed on the graphene surface,which improves the ability to accommodate lithium ions and improves the electrochemical reversible capacity and high rate characteristics of lithium storage.At the same time,maintain the stability of the composites microstructure,enhancing the charge and discharge cycle performance.The MoS2-Sb2S3/rGO composite was synthesized by one-step hydrothermal method using NaMoO4,SbCl3,L-cysteine and GO.The hybrid shows Sb2S3 rods uniformity disperse on the surface or layer of graphene.Sb2S3 rods are wraped up in a MoS2 layer with a thickness of about 45 nm formed by the curled MoS2 nanosheets.The MoS2-Sb2S3/rGO composite electrode has good electrochemical lithium storage performance,its reversible specific capacity is up to 1081 mA h g-1 at 100 mA g-1 current density,and remains at 1084 mA h g-1 after 100 cycles.In addition,the reversible capacity reaches 765 mA h g-1 at a high current density of 1000 mA g-1,and when the current density returns to 100 mA g-1,the specific capacity reaches the initial value again.This hybrid has broad application prospects in anode materials of a new generation of high-performance lithium ion battery. |
PDF Full Text Request