Application of ab initio methods to secondary lithium batteries

Ab initio methods have started to be widely used in materials science for the prediction of properties of metals, alloys and compounds. These methods basically require only the atomic numbers of the constituent species. Such methods not only provide us with predictions of some of the properties of the material (even before synthesizing it) but also help us in understanding the phenomena that control those properties. The use of ab initio methods in the field of electrochemistry is, however, quite recent and rare. In this study, we demonstrate how ab initio methods can be used to investigate the properties of secondary lithium batteries. Particular examples will be given in predicting average insertion voltages in spinel Li-Mn and Li-Co oxides and in layered LiMO2 (M = Ti, V, Mn, Fe, Co and Al) compounds. Additionally, the stability of these compounds to metal reduction and structural stability of LiCoO2 upon lithium removal is investigated. We find that the oxygen anion plays an active role in the electrochemical intercalation of lithium. The amount of electron transfer to oxygen occurring upon lithium intercalation correlates strongly with the cell voltages. The more electron transfer to oxygen occurs, the higher lithium intercalation potential is obtained