Both LiCoO2 and LiNi1/3Mn1/3Co1/3O2 layered cathode materials are investigated in our studies. P3 phase of CoO2, the end member of the LixCoO2, is found in both chemically and electrochemically delithiated materials. Delithiated LixCoO2 specimens decompose into fine Co3O4 and LiCoO2 particles starting at around 200 °C. This decomposing reaction is proved by in-situ X-ray diffraction and in-situ transmission electron microscopy investigations. The structures of pristine and cycled LiNi1/3Mn1/3Co1/3O2 are investigated by electron diffraction. Single and polycrystalline crystals are found in this material. The partial substitution of Co by Ni and Mn in LiNi1/3Mn1/3Co1/3O2 opens up the possibility of different cation configurations in the crystal lattice. Both 3Rm symmetry and superlattices are identified in this material. The number of particles with superlattices in pristine material (40%) is much bigger than cycled material at discharge state (10%).
| Identifer | oai:union.ndltd.org:uno.edu/oai:scholarworks.uno.edu:td-1612 |
| Date | 15 December 2007 |
| Creators | Yi, Tanghong |
| Publisher | ScholarWorks@UNO |
| Source Sets | University of New Orleans |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | University of New Orleans Theses and Dissertations |
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