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Title page for etd-0910110-161057


URN etd-0910110-161057 Statistics This thesis had been viewed 2084 times. Download 12 times.
Author Je-Jang Shiu
Author's Email Address No Public.
Department Materials Engineering
Year 2009 Semester 2
Degree Master Type of Document Master's Thesis
Language Chinese&English Page Count 136
Title Preparation and characterization of LiFePO4 cathode materials with impurities of Fe2P and Li3PO4
Keyword
  • Li3PO4
  • Fe2P
  • LiFePO4
  • LiFePO4
  • Fe2P
  • Li3PO4
  • Abstract In this study, a solution method was used to prepare stoichiometric olivine structured LiFePO4 at various heat treatment temperatures and LiFe1-xPO4 (0≤ x ≤ 0.09) cathode materials. The crystalline structures, compositions, carbon contents, and morphology of the synthesized samples were investigated with XRD, ICP-OES, PSA, EA, and SEM. The electrochemical properties of synthesized samples were analyzed by capacity retention and cyclic voltammetric studies. From the results of XRD, Fe2P was found in samples heat-treated at temperatures higher than 800oC. However, it does not improve the cycling performance and rate capability in comparison with the sample prepared at 775oC which shows the best cycling performance among the prepared samples. Whereas the samples prepared at temperatures higher than 850oC show significant capacity fading that might be attributed to the existence of Li3PO4 impurity and particle size growth. From the diffusivity of Li+ ions in the prepared samples determined from the results of cyclic voltammetric study with various potential scan rates, the existence of Fe2P can increase the diffusion coefficient of lithium ion. Among the prepared LiFe1-xPO4 (0 ≤ x ≤ 0.09) samples, powders prepared with 0.03 ≤ x ≤ 0.05 show better cycling performance than others.
    Advisor Committee
  • She-huang Wu - advisor
  • Chia-Chin Chang - co-chair
  • Hong-Ming Lin - co-chair
  • Wen-Chang Chen - co-chair
  • Files indicate in-campus access only
    Date of Defense 2010-07-12 Date of Submission 2010-09-12


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