Synthesis And Sodium Storage Properties Of Bi₂S₃-MoS₂ Materials

In recent years,sodium-ion batteries?SIBs?have been extensively researched and developed,but the lack of suitable anode materials has gradually become an important bottleneck restricting their development.Therefore,it is of great importance to develop high-performance SIBs anode materials.Bismuth sulfide?Bi₂S₃?has the advantages of low cost and high capacity,but the capacity decay is fast and the cycle life is short.In order to solve these issues mentioned above,we fabricated heterostructured Bi₂S₃-MoS₂ materials to improve the sodium storage performance of Bi₂S₃ material by using bismuth molybdate?Bi₂MoO₆?as precursor.The sodium storage mechanisms of the obtained materials were also analyzed with the help of various characterizations and electrochemical tests.The major contents of this thesis are summarized as following:The Bi₂MoO₆ materials were successfully prepared by adjusting the molar ratio of bismuth nitrate and sodium molybdate via a one-step solvothermal method.The morphologies,crystal structures and chemical compositions of the Bi₂MoO₆materials were characterized by scanning electron microscopy?SEM?,X-ray diffraction?XRD?and X-ray photoelectron spectroscopy?XPS?,and the results showed that the obtained materials were composed of Bi,Mo and O elements,and had good bismuth molybdate structure,good crystallinity.The electrochemical performance test results showed that the Bi₂MoO₆ sample presents an initial specific capacity of 386.16 mAh·g^-1 at 0.05 A g-1,and has good electrochemical activity and stability.Heterostructured Bi₂S₃-MoS₂ materials were fabricated using Bi₂MoO₆ and sulfur powder as precursors followed by a heat treatment.The morphologies,crystal structures and chemical compositions of the Bi₂S₃-MoS₂ materials were characterized by SEM,XRD and XPS,and the results showed that the obtained materials were composed of Bi,Mo and S elements,and had binary heterostructure of bismuth sulfide and molybdenum disulfide,with good crystallinity.Compared with pure bismuth sulfide and molybdenum disulfide,the sodium storage performance of the Bi₂S₃-MoS₂ materials were improved significantly.The rate performance test results showed that the initial specific capacity of the Bi₂S₃-MoS₂ material is 403 mAh·g^-1.At the current density of 5 A·g^-1,the capacity retention rate can still reach 60%.The cyclic stability test results showed that the capacity retention rate of the Bi₂S₃-MoS₂ material is 93% after 600 cycles at the current density of 2 A·g^-1.