Correlation of lithium ion distribution and X-ray absorption near-edge structure in O3- and O2-lithium cobalt oxides from first-principle calculation

Abstract

First-principle calculation was employed to simulate X-ray absorption near-edge structure (XANES) spectroscopy of two typical types of lithium cobalt oxides to clarify the electronic and local structural changes during lithium-ion de-intercalation. The simulated Co K-edge XANES spectra agreed well with the observed spectra. The differences in the shape of the XANES spectra with structural symmetry and/or lithium contents in lithium cobalt oxides were analyzed based on the partial density of state (PDOS) of the excited energy level. First-principle calculation simulations revealed that the cobalt PDOS overlapped with nearby lithium PDOS via oxygen PDOS, and the overlap difference among various Li_1−xCoO₂ could be detected using both the experimental and theoretical Co K-edge XANES spectra.