Controllable Preparation And Application Of Carbon-coated Fe/iron-based Composite Materials

With the development of science and technology, a single material has been unable to meet with the demand of increasingly developing high-technology. Since the concept of nanoparticle was proposed, researchers all over the world start to explore the nanocomposite.. Transition metal oxides and elements have attracted the widespread attention, due to their special properties. Among them, the magnetic nanoparticles(Fe3O4 and Fe etc.) exhibit wide application in many areas. When the particle size reaches nanoscale, these nanoparticles not only exhibit the special chemical, physical and mechanical properties, but also have some special electrical, magnetic, optical properties. Meanwhile, there are many shortcomings, such as instability and easily agglomerate, which limit the application of the magnetic nanoparticles. Therefore, scholars begin the research and practice on magnetic nanoparticles. Carbon materials including amorphous carbon, carbon nanotubes and graphene are widely used to coat magnetic nanoparticles In addition, Ferrous oxide(Fe O), as one of transition metal oxides, has a promising prospect in marine antifouling, fuel cell. The surface modification and surface coating modification to ferrous oxide became one of the research hot spots, which can improve the chemical stability and carefully avoid the disproportionate reaction.This thesis focused on the controllable preparation of Fe@C, Fe3O4@C, Fe O@C and Fe@Fe3C@C by a simple thermal reduction process. The experimental methods have the following advantages: low cost, less pollution, and high yield. Furthermore, we explore the application of the products in terms of lithium ion batteries.Firstly, Fe@C nanoparticles were synthesized through a thermal reduction process, using cheap and available ferric oxide as a source of iron, homemade liquid acrylonitrile oligomer(LANO) as carbon source and reducing agent. In the process of the reaction, the ratio of m(Fe2O3) in raw material was 40 wt%, 50 wt% and 60 wt%, the reaction temperature was 800?-4h. The effect of technical parameters on composition, structure, morphology and magnetism were explored, by changing the reaction temperature and soaking time. The samples of 60%-800?-8h exhibit a high saturation magnetization(~185 emu/g) successfully. The products were characterized by XRD, SEM, TEM, VSM.Secondly, LANO and ferric oxide were used to synthesize Fe3O4@C nanoparticles,and the experimental equipment and the raw materials were almost as the above section, the ratio of m(Fe2O3) in raw material was m(Fe2O3)wt% = 90wt%, the reaction temperature was 600?-8h. In lithium ion battery filed, Fe3O4@C showes great electrochemical properties in the charge/discharge processes. Through the research,(Fe O@C) was prepared at the ratio m(Fe2O3) in raw material m(Fe2O3)wt% = 90wt%, the reaction temperature is 800?-2h, 800?-8h, 900?-8h.Finally, Fe@Fe3C@C was synthesized by using LANO and ferric oxide, the ratio of m(Fe2O3) in raw material was 5%, 10%, 30%, 40%, the reaction temperature was 1300?-4h, respectively. Raman spectra of the samples 5%-1300?-4h present the significant characteristic of 2D peak of graphene at 2694cm-1. Through the application of the lithium ion battery andoe, Fe@Fe3C@C nanoparticles present high reversible capacity and stable cycle performance, then we discussed the influence of the electrochemical properties by the change of the reaction condition.