Synthesis And Electrochemical Prorerties Of Antimony-based Nanocomposites

Metal antimony has attracted people’s extensive attention and research in the field of energy storage,because of its high theoretical specific capacity,abundant reserves,and low price and so on.However,since Li₃Sb is formed during the charge and discharge process and caused large volume expansion（175%）,which may lead to electrode powdering and irreversible attenuation of capacity.Current research shows that the design of a antimony-based nanocomposite structure is an effective method to alleviate this problem.The use of molybdenum disulfide and carbon as the cladding layer can greatly alleviate the large volume expansion of the antimony in the lithium ion insertion process,and it is an effective method to improve the rate performance of the metal antimony.Through the introduction of other metals can form intermetallic compounds with antimony,can improved the utilization of antimony can and provided a soft buffer frame and conductive network,which is also an effective method of modification.In this paper,three antimony-based nanocomposites were synthesized by simple hydrothermal,cladding and sintering processes.They were Sb@MoS₂@C,Sb@Sb₂S₃@MoS₂@C nanocomposites and Sb@CoSb₂@C nanospheres.The main contents of this paper are as follows:（1）Sb@MoS₂@C nanocomposite was synthesized by using antimony sulfide nanorods as antimony source and molybdenum disulfide and carbon as cladding layers.By XRD and XPS analysis,the composition of the sample and the composition of each element were further confirmed.The morphology was analyzed by SEM and TEM.The composite was observed to be semicircular.Sb@MoS₂@C composites were assembled into electrodes and tested.At a high current density of 5 A g^-1,the discharge specific capacity is 437 mAh g^-1,indicating that the Sb@MoS₂@C nanocomposites have excellent high rate performance,and also have a high first cycle coulombic efficiency and excellent stability by long cycle tests.（2）Sb@Sb₂S₃@MoS₂@C nanocomposites were synthesized by using antimony sulfide nanorods as antimony source,phosphomolybdic acid and pyrrole as molybdenum source and carbon source,respectively,and by setting a reasonable sintering temperature and time.By XRD and XPS analysis,the composition of the sample and the chemical composition of each element were further confirmed.The morphology of the composite was observed by SEM and TEM,can see the composite had a rod-like structure.The inside was antimony and antimony sulfide,and the outer was a sheet of molybdenum disulfide and carbon.The Sb@Sb₂S₃@MoS₂@C composites were assembled into electrodes and tested.At a high current density of 5 A g^-1,the discharge specific capacity was 481 mAh g^-1,indicating that the Sb@Sb₂S₃@MoS₂@C nanocomposites have excellent high rate performance,and also have a high first cycle coulombic efficiency and excellent cycling performance.（3）The Sb@C nanospheres structure were obtained after high-temperature carbonization of Sb₂S₃@PDA.And used antimony chloride as the antimony source,dopamine was the carbon source.However,the Sb@C nanospheres have poor rate performance.The introduction of an appropriate amount of cobalt can forms an intermetallic compound CoSb₂ with antimony,resulting in Sb@CoSb₂@C nanospheres structure.Through XRD analysis,it was determined that the sample contains part of CoSb₂.After SEM analysis,it was observed that the diameter of Sb@CoSb₂@C nanospheres were between 100-150 nm,but there was a phenomenon of agglomeration.The Sb@CoSb₂@C nanospheres material was assembled into electrodes and tested.At a high current density of 5 A g^-1,the discharge specific capacity is 476 mAh g^-1,which indicates that the Sb@CoSb₂@C nanocomposites have excellent high rate performance,and also have a high first cycle coulombic efficiency and excellent cycling performance.