Accession Number : ADA294726

Title :   Lithium-7 NMR Studies Of Li(1-x)CoO2 Battery Cathodes.

Descriptive Note : Interim technical rept.,

Corporate Author : HUNTER COLL NEW YORK DEPT OF PHYSICS AND ASTRONOMY

Personal Author(s) : Ouyang, B. ; Cao, X. ; Lin, H. W. ; Slane, S. ; Kostov, S.

PDF Url : ADA294726

Report Date : 26 MAY 1995

Pagination or Media Count : 12

Abstract : Lithium-deficient cathode materials Li(1-x)CoO2, where x = 0.1, 0.4 and 0.6 were prepared electrochemically from the stoichiometric parent compound (x = 0.0). The materials were observed to be air-stable, and x-ray diffraction characterization yielded good agreement with the in situ studies of Dahn and co-workers, regarding changes in lattice parameters. In addition to both static and magic angle spinning (MAS) 7Li NMR, measurements, the samples were investigated by EPR and cobalt K-edge NEXAFS. The removal of Li is accompanied by compensating electrons from the Co d-orbitals, as evidenced by both shifts in the NEXAFS peak and the observation of EPR signals due to spins localized on the Co ions. These spins, in turn, result in dramatic 7Li chemical shifts (89 ppm for x = 0.6) and line broadening. Whereas MAS analysis of Li0.9CoO2 indicates two magnetically inequivalent Li sites, the spectra become too broad to resolve different sites for higher values of x. Finally NMR linewidth and spin- lattice relaxation measurements as a function of temperature suggest a modest increase in Li+ ion mobility for Li-deficient samples as compared to the parent compound. jg

Descriptors :   *NUCLEAR MAGNETIC RESONANCE, *CATHODES, *LITHIUM BATTERIES, *COBALT, ANGLES, IONS, STABILITY, MOBILITY, AIR, COMPOSITE MATERIALS, X RAY DIFFRACTION, ELECTROCHEMISTRY, ELECTRONS, OXIDES, LATTICE DYNAMICS, COMPENSATION, STATICS, STOICHIOMETRY, X RAY ABSORPTION ANALYSIS, ELECTRON PARAMAGNETIC RESONANCE.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Electrochemical Energy Storage
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE