First-principles prediction of vacancy order-disorder and intercalation battery voltages in Li_xCoO₂

We present a first-principles technique for predicting the ordered vacancy ground states, intercalation voltage profiles, and voltage-temperature phase diagrams of Li intercalation battery electrodes. Application to the Li_xCoO₂ system yields correctly the observed ordered vacancy phases. We further predict the existence of additional ordered phases, their thermodynamic stability ranges, and their intercalation voltages in Li_xCoO₂/Li battery cells. Our calculations provide insight into the remarkable electronic stability of this system with respect to Li removal: A rehybridization of the Co-O orbitals acts to restore charge to the Co site (“self-regulating response”), thereby minimizing the effect of the perturbation.