Electrochemical properties of hydrothermally obtained LiCo{sub 1{minus}x}Fe{sub x}O{sub 2} as a positive electrode material for rechargeable lithium batteries
- and others
Changes in the crystal structure and transition metal valancy in LiFe{sub x}Co{sub 1{minus}x}O{sub 2}(0 {le} x {le} 0.25) positive electrodes during the charge-discharge of Li/LiFe{sub x}Co{sub 1{minus}x}O{sub 2} cells were examined using ex situ X-ray diffraction measurements, Fe and Co K-X-ray adsorption near edge spectroscopy (XANES) and {sup 57}Fe Mossbauer spectroscopy. An iron-doped host material with rhombohedral symmetry was obtained up to 25% Fe per formula unit in LiCoO{sub 2} by hydrothermal reaction below 300 C from a mixture of Co{sup 3+}-Fe{sup 3+} coprecipitate (iron-doped CoOOH) and LiOH. No symmetry changes were observed during electrochemical charge-discharge tests up to the tenth cycle. The structures of Li-extracted and reinserted samples were determined by a model similar to LiCoO{sub 2} prepared at low temperature in which Li ions are located at the interstitial 6c and octahedral 3a sites. {sup 57}Fe Mossbauer and Fe and Co K-XANES spectra at 293 K indicated the presence of tetravalent Fe ions upon oxidation up to 4.3 V.
- Research Organization:
- Osaka National Research Inst. (JP)
- OSTI ID:
- 20030652
- Journal Information:
- Journal of the Electrochemical Society, Vol. 147, Issue 3; Other Information: PBD: Mar 2000; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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