INvestigations of the Local Structure in lithium Nickel CObalt Oxide Cathode Mathrials

摘要

We have studied the modifications of structural and physical properties which occur during delithiation of lithium-nickel-cobalt oxide cathode materials. Long-range and short-range orders have been ivestigated using XRD, Raman and FTIR spectroscopies. Different samples Li_xNi_0.7Co_0.3O_2 were prepared by electrochemical lithium deintercalation from LiNI_0.7Co_0.3O_2. Electrochemical extraction of lithium was carried out using Li/LiCLO_4 in PC/LINI_0.7CO_o.3O_2 cells in the potentiometric method with potential step of 10mV.During the first charge of the Li//LI_xNi_0.7Co_0.3O_2 cell, the change inthe cathode structure was followed by x-ray powder diffraction nad vibrational spectroscoplies at room temperature. A good correlation is found between XRD data and the local environment of the host lattice. Detailled analysis of vibrational spectra shows that the octahedral oxygen environment of LI~+ ions remains stable in the investigated domain of concentration.