Synthesis And Performance Of Novel LiMPO₄（M=Fe, Mn） And SnO₂Nanomatericals

Nanomaterial is special material which has many excellent properties. It hasbroad application prospect in medical and biological engineering, industrial catalysis,new energy material and defence-related science and technology.This thesis combining with the domestic and foreign relevant research work, andaccording to the experimental results, the application for functional nanomaterials inlithium ion battery cathode materials and the semiconductor photocatalyst, has beendiscussed preliminary, and the future development direction of nanomaterials isprospected. In this thesis, we have finished the following two works:（1） New energymaterials--LiFePO₄cathode material for lithium ion batteries. The LiFePO₄materialmorphology and size can be controlled by adjusting the condition of reaction, whichcan greatly enhance the electrochemical properties.（2） Green technology—SnO₂semiconductor photocatalyst. Moreover, adjusting the pH value of precursor solutionis an efficient way to control the morphology of nanoparticles. The whole thesis fallsinto four chapters:Chapter1: we reviewed the research progress of functional nanomaterials. Theworking principle of lithium-ion batteries and semiconductor photocatalyst wasdescribed in detail in this chapter. Furthermore, the effective ways to improveelectrode materials and photocatalysts also discussed.Chapter2: Spindle-like carbon coated LiFePO₄（LiFePO₄/C） composites have beensuccessfully synthesized via a novel one-pot supercritical methanol method. Theproducts were characterized by XRD、TEM、HRTEM、XPS and TGA. The particlesize, morphology and electrochemical reactivity changed with the concentration oflithium and carbon source. A possible morphology evolution process was alsoproposed. The glucose not only facilitates the formation of single crystalline LiFePO₄,but also gives an amorphous carbon layer on the surface LiFePO₄spindles.Furthermore, at current rate of0.2C between2.0and4.5V, the cell exhibits goodelectrochemical properties, the first discharge capacity of135mAh·g1. Chapter3: A novel water-oil-water three-phase hydrothermal method was used toprepare SnO₂nanocrystal．XRD，TEM，HRTEM，DRS were used to characterize thecatalysts．The results indicated that the size of the SnO₂nanoparticles could becontrolled by adjusting the NaCl concentration. When the concentration of NaCl is1.13mol/L，SnO₂grain size is about6nm．Furthermore, adjusting the pH value ofprecursor solution is an efficient way to control the morphology of nanoparticleswhen other synthetic parameters are fixed. When the solution is alkaline, SnO₂nanorods were obtained. The formation process of SnO₂nanocrystal was investigatedin simple in this chapter. Moreover，the SnO₂nanocrystal showed high photocatalyticdegradation activity for rhodamine B when exposed to xenon light irradiation, RhBdegradation within10min to colorless.Chapter4: In view of the above problems, we summarized the main results of thisthesis research, and provide the development direction of functional nanomaterials.