Computer Simulation of the Phase Stabilities of Lithiated TiO2 Polymorphs

Abstract

The structure and phase stability of a series of lithiated titania polymorphs were determined using energy minimizations of the periodic bulk crystal structures and both density functional theory (DFT) and a potential shell model. The DFT calculations were performed spin unrestricted following the linear combination of atomic orbital approach with the B3LYP exchange-correlation potential. For the potential shell model, a new set of force field parameters was derived, independently of the DFT calculations, to describe the lithium−lattice interactions. The eight polymorphs considered in this study are the rutile, anatase, brookite, TiO2−B, ramsdellite, hollandite, spinel, and hexagonal structures. The lithium to titanium ratio, x, of each lithiated titania polymorph was varied from 0.0 to 1.0 with 0.25 increments. The potential model predictions were found to be in good agreement with the structure and energetics of the lithiated titania polymorphs determined from DFT calculations, at all lithium contents. ...