Interlayer mixing in lithium nickel manganese cobalt oxide cathode materials for rechargeable lithium batteries
Composition of LiNi1/3Mn1/3Co1/3O2 and its analogous Li[(Ni0.5Mn0.5)1-xCox]O2 were prepared by conventional solid state method to evaluate the effect of reducing cobalt contents to the layered rock salt-type cathode materials. Structural analysis using Rietveld refinement of conventional XRD data...
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| Format: | Thesis |
| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44121/1/p.1-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/44121/2/full%20text.pdf |
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| Summary: | Composition of LiNi1/3Mn1/3Co1/3O2 and its analogous Li[(Ni0.5Mn0.5)1-xCox]O2 were
prepared by conventional solid state method to evaluate the effect of reducing cobalt
contents to the layered rock salt-type cathode materials. Structural analysis using
Rietveld refinement of conventional XRD data revealed that the amount of cobalt
contents is highly correlated to their structural stability. Solid solution limit for phasepure
samples that were prepared is about x > 0.2 for Li[(Ni0.5Mn0.5)1-xCox]O2. The
amount of interlayer mixing increased for samples contain 20% or less cobalt contents.
The results showed that the minimum amount of interlayer mixing that could be
achieved is about 3.8% for the composition of LiNi0.4Mn0.4Co0.2O2 that was prepared at
950 oC in oxygen compared to LiNi1/3Mn1/3Co1/3O2 which is about 2%. However, the
amount of interlayer mixing varies as a function of temperatures and conditions.
Systematic investigation have been done to optimize refinement parameters and to
validate structural model based on LiCoO2 as a standard. On the other hand, the initial
charge and discharge capacities during battery cycling for LiNi0.4Mn0.4Co0.2O2 is
relatively high which recorded ~323 mAh g-1 and ~229 mAh g-1 respectively. But it has
high irreversible capacity loss after a few cycles that are probably due to structural
instability during charge and discharge. |
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