Lithium intercalation reactions with transition metal oxides
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University of Cape Town
An investigation of several lithium transition metal oxide systems has been undertaken with the aim of synthesising an optimised LiM0₂ compound (M = Mn, Co or Co/Ni mixtures) for application as a cathode in rechargeab1e lithium batteries. Attention has been focused on systems which show promise for application as cathodes in rocking-chair cells which do not contain metallic lithium anodes. A novel lithium cobalt oxide, LT-LiCoO₂ (LT for low temperature), has been synthesised at 400°C. This compound has near-cubic symmetry and can be indexed to either a trigonal unit cell (space group R3m) with a=2.830(1)Å and c=l3.875(8) Å, or to a face-centred cubic unit cell (space group Fd3m) with a=8.002(1)A. The near-cubic symmetry is maintained on delithiation. Neutron and X-ray powder diffraction refinement of the LT-LiCoO₂ sample has shown it to be best described as a layered structure (R3m symmetry) with approximately 6% of the cobalt cations in the predominantly lithium layer and vice versa. An acid-leached sample LT-Liₒ₄.4CoO₂ was, however, shown to have a defect spinel structure.
Gummow, R. 1993. Lithium intercalation reactions with transition metal oxides. University of Cape Town.