Preparation Of Anode Material Of Molybdenum Disulfide Complex And Its Application To High-performance Sodium Ion Battery

Sodium-ion batteries（SIBs）have the significant advantages of low cost and high capacity,which show great application potential in large-scale energy storage systems.The development of electrode materials for high performance sodium ion batteries is one of the keys to the development of sodium ion batteries.Two-dimensional layered transition metal sulfides have the advantages of controllable morphology,capacitive interlayer spacing,and high theoretical potential,which are expected to be the ideal cathode material for sodium ion battery.However,the transition metal sulfides suffer from inherent defects such as low electronic conductivity,high bulk expansion rate,and easy pulverization,which severely hinder their further development.To address the above issues,three transition metal sulfide composite nanomaterials have been fabricated to significantly improve the performance of sodium ion batteries.The main contents are as follows:1.Preparation of a composite MoS₂@C hollow cell for storage of sodium.MoO₃templates were first prepared by hydrothermal methods,and then carbon and sulfur sources were introduced to grow MoS₂@C sheets on the surface of the MoO₃nanowire templates.Finally,the MoO₃template was removed in the alkaline solution after annealing gave the MoS₂@C composite.When used as the anode of a sodium-ion battery,the initial discharge specific capacity is 1003.5 m Ah g^-1at 100 m A g^-1,and the coulomb efficiency reaches 66.2%.After 100 cycles,a specific capacity of 401.2 m Ah g^-1could still be achieved.The formation of MoS₂@C heterojunction interfaces can accelerate the mobility of ions.The carbon material composition enhances the conductivity of the material and accelerates electrochemical reactions.The hollow nanorod structure increases the contact area between the material and the electrolyte and reduces the reaction energy barrier.2.Preparation of the expanded interlayer 1T-MoS₂@WS₂@CC composite material for sodium storage performance.1T phase MoS₂@WS₂@CC nanosheets were grown in situ on an activated carbon cloth（CC）by a two-step hydrothermal method.Making composite materials with conductive CC as the substrate can increase the conductivity of the material,effectively prevent the agglomeration of the material in the growth process,increase the specific capacity.In addition,the wrapping of the 1T phase MoS₂nanosheets on the surface of the 1T phase WS₂nanosheets provides the material with a richer heterojunction active site,enhancing the electrochemical performance.The large layer spacing favors the reversible disembedding of the ions and enhances the kinetic rate.At100 m A g^-1after 100 cycles,the specific discharge capacity can reach 529.4 m Ah g^-1.At a high current density of 1 A g^-1,the specific capacity reached 259.2 mAhg^-1after 60cycles.3.Preparation of MoS₂/Re S₂hollow nanospheric heterojunctions for sodium storage performance.Si O₂templates were prepared by precipitation at room temperature and MoS₂/Re S₂nanosheets were grown on the template surface by hydrothermal reaction.Finally,the MoS₂/Re S₂hollow nanospheric composite was obtained by sacrificing template.The synergistic effect of the high specific volume energy density and the heterostructure of MoS₂/Re S₂composites favors the improvement of electrochemical properties.The hollow structure is beneficial for increasing the contact area between the material and the electrolyte,reducing the energy barrier and facilitating fast transport of ions.At 100 m Ah g^-1,the specific discharge capacity reached 315.9 m Ah g^-1after 150cycles,with 73.9%of the capacity retained.At 1 A g^-1,the specific discharge capacity is still 98.3 m Ah g^-1after 1000 cycles,indicating excellent sodium storage performance of the material.