Solid-state redox reactions of LiCoO[sub 2] (R[bar 3]m) for 4 volt secondary lithium cells
- Osaka City Univ. (Japan)
LiCoO[sub 2] (R[bar 3]m; a = 2.82 [angstrom], c = 14.1 [angstrom] in hexagonal setting) was prepared and examined in nonaqueous lithium cells using 1M LiClO[sub 4] propylene carbonate solution at 30 C. The oxidation of LiCoO[sub 2] and the reduction of Li[sub 1[minus]x]CoO[sub 2] proceeded reversibly in the voltage region above 3.9 V. X-ray diffraction (XRD) examinations indicated the reaction proceeded in a topotactic manner, i.e., two-phase reactions (0 < x < 1/4 and 3/4 < x < 1 in Li[sub 1[minus]x]CoO[sub 2]) and a single-phase reaction (1/4 < x < 3/4). A monoclinic phase was observed in 3/4 < x < 1 in addition to that at about x = 0.45. Detailed open-circuit voltage measurements were carried out. The open-circuit voltage are invariable at 3.92 V for 0 < x < 1/4 and at 4.50 V for 3/4 < x < 1. The two straight lines are connected smoothly by a composition-dependent curve for 1/4 < x < 3/4, which was consistent with the XRD observations. The differences and similarities between the solid-state redox reactions of LiCoO[sub 2] and LiNiO[sub 2] were discussed by comparing the structural and electrochemical data. Possible lithium ordering at x = 1/4 and 3/4 for this type of material is described in terms of a [2 x 2] superlattice in a triangular lattice of sites.
- OSTI ID:
- 6667060
- Journal Information:
- Journal of the Electrochemical Society; (United States), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 141:11; ISSN JESOAN; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
250903* -- Energy Storage-- Batteries-- Materials
Components
& Auxiliaries
ALKALI METAL COMPOUNDS
CATHODES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
CHLORATES
CHLORINE COMPOUNDS
COBALT COMPOUNDS
COBALT OXIDES
DATA
ELECTRIC BATTERIES
ELECTROCHEMICAL CELLS
ELECTROCHEMISTRY
ELECTRODES
EXPERIMENTAL DATA
FABRICATION
HALOGEN COMPOUNDS
INFORMATION
LITHIUM COMPOUNDS
LITHIUM OXIDES
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
REDOX REACTIONS
TRANSITION ELEMENT COMPOUNDS