Synthesis And Electrochemical Performances Of LiFePO₄ For Lithium-Ion Battery Cathode Material

Olivine LiFePO₄ is a new kind of cathode material for lithium-ion battery. It has a relatively large theoretical capacity of 170mAh/g. This material is cheap and environmentally friendly, thermally stable in the fully charged state. LiFePO₄ has a low electronic conductivity, and its cycle ability at large charging/discharging current should be improved. This thesis focuses on olivine LiFePO₄ synthesis by modified solid state reaction and electrochemical performances, the main aspects follow:1) Study on the electrochemical performances of LiFePO₄ by reducing sucrose solid state reactionThe effect of the amount of sucrose, synthesis temperature and Particle size of produce are discussed. The results show that The products with the amount of sucrose at 12% , sintered at 650 and Particle size at 2-3microns possessed excellent electrochemical performance. The crystalline structure, granularity and morphology of particles of the sample are investigated by X-ray diffraction (XRD), particle diameter measure system, scanning electron microscope (SEM) and transmission electron microscope (TEM).2) Study on the electrochemical performances of LiFePO₄ by different additives solid state reactionThe electrochemical performances of LiFePO₄ by dextrose , lactose , solubility amylum and nylon-66 solid state reaction are discussed. The results show that the electrochemical performances of LiFePO₄ samples prepared by nylon-66, lactose and dextrose have better capacities and cycle performances. They show capacities of about 150mAh/g at a current density of 0.3 mA/cm2.3) Study on the electrochemical performances of LiFePO₄ by different materials of iron solid state reactionThe electrochemical performances of LiFePO₄ by Fe₃O₄ Fe(OH)₃ and FePO4 solid state reaction are discussed. The results show that the electrochemical performances of LiFePO₄ prepared by FePO4 have a better capacity and cycle performance. The capacity has 147.7mAh/g at a current density of 0.3 mA/cm2.4) Study on the electrochemical performances of LiFePO₄ dopedLiFePO₄ doped with A1₂O₃n CuO Dy₂O₃ was synthesized by solid state reaction. 'The result indicates that the Al doped take from electrochemical performances of...