Synthesis And Characterization Of The Phosphate-based Lithium-ion Cathode Nanomaterial

LiFeP04,LiMnPO4and LiCoPO4is a new cathode material for lithium-ion battery. It has lots of advantages, such as plentiful resources, low cost, environmental friendliness, high specific capacity, stability of discharge voltage, good thermal stability, long cycle life and high safety.This thesis mainly studied the different synthesis methods and synthesis conditions on the positive effect on structure and electrochemical properties of the material.1.LiFePO4cathode material was synthesized by solvothermal method, determined the best preparation conditions of LiFePO4battery anode materials, and the optimum preparation conditions of solvent hot method synthesis performance of LiFePO4battery anode materials were studied. By means of XRD and IR analysis under different preparation conditions on the synthesis of LiFePO4cathode material of characterization, the electrochemical performance of LiFePO4/C has carried on the thorough analysis. The results showed that LiFePO4cathode material offers pure phase, good crystallinity, small size and uniform features when stoichiometric ratio of FeSO4·7H2O,H3PO4and LiOHH2O is1:1:1.1.the reaction temperature is200℃, reaction time,10h, when the pH=10of LiFePO4cathode material phase pure, good crystalline particle size small and uniform; After carbon coating process of LiFePO4/C shows good electrochemical performance, under the0.2C ratio, discharge specific capacity of139.2mAh/g, circulation after20times still have125.3mAh/g specific capacity, the capacity retention rate of93.3%, showing a better cycle life.2. LiMnPO4synthesis by hydrothermal method the cathode material, and through the analysis of means such as XRD, IR, SEM and BET structure and morphology of the samples for the analysis and characterization of the system. Analysis shows that the product belongs to the orthogonal crystal system, olivine structure, space group for Pmnb. LiMnPO4nano powder morphology, all for the smooth surface of the polyhedral prism shape crystal, and crystal has the understanding. All affect the hydrothermal temperature and time on synthesis, when the time for10h, hot water temperature is160℃, the resulting LiMnPO4phase pure, good crystalline particle size small and uniform.3. LiCOPO4synthesis by hydrothermal method the cathode material, on the basis of Co(OH)2precursor, at low pH, temperature and time conditions to generate the six-party and intermediate product of trigonal system with increasing reaction pH, temperature, time, under the suitable reaction conditions, the intermediate gradually dissolve, fine is smaller, the formation of acicular crystal, the resulting less pure crystalline good orthogonal prism LiCoPO4crystals.