RAMAN-STUDY OF LAYERED ROCK-SALT LICOO2 AND ITS ELECTROCHEMICAL LITHIUM DEINTERCALATION

Unpolarized and polarized Raman spectra (200-800 cm(-1)) of LiCoO2 wit h a layered rock-salt structure were measured, The Raman-active lattic e modes of LiCoO2 were assigned by polarized Raman measurements of a c -axis oriented thin film, The variation of the Raman spectra of Li1-xC oO2 powder prepared by electrochemical lithium deintercalation was inv estigated, and the spectral changes were well correlated with the stru ctural changes determined by x-ray diffraction except that peak splitt ing by the distortion in the monoclinic phase was not observed, The ob served line broadening of the second hexagonal phase and the monoclini c phase indicated that the lithium ions remaining in the lattice after deintercalation randomly occupy the available sites on the lithium pl anes in the lattice the layered rock-salt structure, (C) 1997 John Wil ey & Sons, Ltd.