Lithium diffusion mechanisms in layered intercalation compounds

We investigate the mechanisms of lithium diffusion in layered intercalation compounds from first-principles. We focus on LixCoO2 and find that lithium diffusion in this compound occurs predominantly with a divacancy mechanism . First-principles calculations predict that the activation barrier is very sensitive to the lithium concentration due to the strongly varying c-latti ce parameter of the host and the change in effective valence of the cobalt ions. This translates into a diffusion coefficient that varies by several o rders of magnitude with state of charge. (C) 2001 Elsevier Science B.V. All rights reserved.