Synthesis, Modification And Electrochemical Properties Of Metal Sulfides For Lithium Ion Batteries

The development in new types of materials for high energy density batteries, which are low-cost and environmental friendly, has become a hotspot and focus. Metal sulfide, due to the advantages of high theoretical specific capacity, natural abundance, cheap and easy to obtain, becomes a promising electrode material for lithium ion battery. Here, three kinds of sulfide ((Bismuth Sulfide (B12S3), Copper Tin Sulfide (Cu2SnS3), copper Stibonium Sulfide (CuSbS2)) are studied. The preparation are Optimized and the morphology are controlled reasonably as well. Following that, modifying the structure with different carbon materials, like carbon nanotubes (CNTs) and graphene oxide (GO). Finally, the promising application of the metal sulfides or modified metal sulfides for lithium ion batteries have also been investigated. The main conclusions are as follows:1) Binary sulfide electrode material-Bi2S3:The dandelion-like B12S3microspheres are synthesized via a reflux synthetic route in which bismuth nitrate (Bi(NO3)3·5H2O) and thiourea are employed to supply Bi and S source. The CNTs@Bi2S3composites are obtained by modifying novel Bi2S3with CNTs and the CNTs are just twine or scatter among the microspheres. The result shows that the introduction of CNTs can increase the capacity and enhance the cyclability of pure Bi2S3with the initial discharging capacity of899.1mAh g-1and of247.9mAh g-1the maintained after50cycles, respectively. Furthermore, the spindle-like Bi2S3particles are successfully synthesized by a simple one-pot hydrothermal route while the Bi2Ss/RGO composites are prepared by utilizing GO as modified agent. The Bi2S3particles in Bi2S3/RGO composites are dispersed on the RGO nanosheets. Electrochemical tests show that Bi2S3/RGO composites exhibit an extraordinary capacity of1073.1mAh g-1with excellent cycling stability (50cycles,400.5mAh g-1) and high rate capability(1000mA g-1, about300mAh g-1) compared to pure Bi2S3particles prepared by a similar route in the absence of GO, suggesting a promising electrode material for lithium ion batteries. 2) Ternary sulfide electrode material-Cu2SnS3:the porous Cu2SnS3hollow microspheres (P-CTS-HMSs) are successfully synthesized via an Ethylene Diamine Tetraacetic Acid (EDTA-Na2) assisted hydrothermal route, which recommends Copper chloride (CuCl), tetrachlorostannane pentahydrate (SnCl4·5H2O) and L-cysteine as raw materials. The Cu2SnS3/RGO (CTS/RGO) composites are prepared by introducing GO as modified agent and the CTS microspheres are in situ anchored on RGO nanosheets. Finally, the results show that the CTS/RGO composites have an extraordinary performance with improved initial coulomb efficiency, higher initial discharge capacity (1514.6mAh g-1) and good cycle performance (100th,425.6mAh g-1) and rate ability (1000mA g-1,220mAh g-1) compared to pure Cu2SnS3(P-CTS-HMSs), exhibiting a good lithium storage performance.3) CuSbS2electrode meterial:CuSbS2have been obtained via a one-pot solvothermal method and a hot-injection method. The electrochemical properties of the novel ternary CuSbS2is investigated as active material in lithium ion battery. The initial discharge capacity of CuSbS2blocks prepared with solvothermal method is877.6mAh g-1, but the lithiation capacity is only224.9mAh g-1after15cycles. On the other side, the initial discharge capacity of cubic CuSbS2obtained from hot injection route is1090mAh g-1, and the capacity is only85.7mAhg-1after50cycles. Therefore, further improvement in cyclic stability is still needed. There are53pictures,10tables and91references.