Lithium insertion and mobility in the TiO2-anatase/titanate structure: A periodic DFT study

The Li atom positions are calculated in LixTiO2 anatase, by means of periodic density functional theory calculations, followed by the predictions of the energy barriers for the mobility of Li atoms, done for the first time for a range of Li concentrations (x < 0.5). A fivefold-coordinated environment was confirmed for the Li atoms in the empty octahedral sites in titanate (orthorhombic) LixTiO2 structures. For the low Li concentration structures (anatase) a fourfold-coordination was found for the Li atoms. The energy barrier to move a Li atom from one octahedral site to a neighboring one is found to converge for x value higher than 0.5-0.6 eV. The barrier used to calculate the hopping rate was found to decrease with increasing Li concentration.