Synthesis Of MoS₂ And Si/C Composites And Their Lithium-ion Storage Properties

Due to the high operating voltage, high energy densities, high power densities and low memory effect, Lithium-ion batteries were widely used in variety kinds of portable devices. With the flourish development of new energy vehicles technologies in recent years, the conventional carbon-based anode materials couldn’t satisfy the increasingly requirements of the booming power battery markets. It means that the development of novel Lithium-ion anode materials have a great significance.Compared with carbon-based anode materials, new anode materials based on alloy or translation mechanism have much higher specific capacity. But these kinds of materials are usually present a dramatically cycling performance decrease, which can be attributed to the large volume effect of the materials during the lithiation/delithiation process. This paper researched four different anode materials（mainly based on MoS₂ and Si/C composites） and their corresponding electrochemistry properties.The specific research contents and innovations of this dissertation are as follows:（1） The flower-like MoS₂/RGO composites were synthesized by a simple hydrothermal process, then Fe（C5H5）2 was used as a raw material to load iron-oxide on the MoS₂/RGO substrates by solvothermal and microwave method, respectively.By compared the structure and electrochemistry performance of the samples, It is found that the N-MoS₂/RGO-CNTs-Fe Ox composites synthesized by microwave process showed apparently superiority, It had a reversible capacity of 935 m Ah/g after200 cycles at the current density of 0.2 A/g, and over 480 m Ah/g even surveyed at a high current density of 2.0 A/g. The results indicated the unique morphology ofN-MoS₂/RGO-CNTs-Fe Ox can improve the electron conductivity and structure stability.（2） The spindle-shaped Fe OOH nanorods were synthesized by facile low-temprature hydrothermal strategy using Fe Cl3·6 H2 O as the precursor. Then the core-shell Fe₃O₄@C@MoS₂ composites were synthesized by a continuous hydrothermal process and high temperature treatment. The optimized Fe₃O₄@C@MoS₂ composites showed a reversible capacity of 813 m Ah/g after 200 cycles at 0.2 A/g,and it could maintained a capacity of 432 m Ah/g at a high current density of 2.0 A/g. It was proved that the composite shell, which was comprised by MoS₂ and amorphous carbon, provided a protective effect to the Fe₃O₄ anode materials during the charge/discharge process.（3） The Si/G-Si C-Fe₃Si-CNTs composites were synthesized through a microwave process, where Si/G composites, which were prepared by using Graphene oxide and nano-silicon, were used as raw materials. The characterization and electrochemistry properties results proved the uniform CNTs network not only improved the electrical conductivity, but also provided some advantages to the structure stability of composites.（4） The homogeneous silicon nanoparticles loaded Graphite flake were produced by a mechanical ball milling method. Then some different additional carbon sources were introduced into the binary composite. Both the carbon sources and subsequent calcination temperature were optimized. It was found that the Si/G-PAN-800 composites showed the best lithium-ion storage capacities, which was presented a reversible capacity of 670 m Ah/g after 100 cycles at 0.2 A/g. even surveyed at a high current density of 2.0 A/g, the lithium-ion storage capacities could also be over 215 m Ah/g. The improved electrochemistry properties were mainly caused by the better electrical conductivity and structure stability of the material, which should be attributed to the PAN carbonization.