Electronic Properties and Lattice Dynamics of LixCoO2 and NaxCoO2 (x = 0, 0.5, 1) Studied by Hybrid Density Functional Theory

Abstract

A systematic hybrid density functional theory study on the electronic and vibrational properties of MxCoO2 compounds with M = Li, Na and (Formula presented.) is reported. The used DFT-PBE0 method describes the structural parameters of the studied compounds well in comparison to experimental data. All studied magnetic species are treated as ferromagnets and the Co(IV) atoms possess a magnetic moment of 1.2 μB. At 0 K, (Formula presented.) favors a monoclinic structure very close to trigonal symmetry and behaves as a Mott insulator. The electronic bandgap increases as x increases from 0 to 1. The simulated infrared and Raman spectra together with full phonon dispersion relations show that the intercalation of Li and Na ions affects the lattice dynamics of CoO2 in a different way.