A first principles investigation of lithium intercalation in TiO2-B

The intercalation of lithium into the polymorph of titania, TiO2-B, has been examined using first principles methods, based on the Generalized Gradient Approximation within density functional theory. Three symmetry unique sites have been identified for the preferential location of lithium within the structure at low concentration, as well as the diffusion pathways between these sites. Lithium is found to bind most favourably at a site close to the titania octahedral layer, while the lowest activation energy for diffusion of 27 kJ mol(-1) is found for diffusion along the open channel parallel to the b axis of the material. The need to activate lithium towards diffusion through the population of higher energy binding sites within the channel, along with the larger barrier for lithium to migrate through the sidewalls of nanotubular TiO2-B, provides an explanation for many of the observed experimental electrochemical properties of this potential battery material.