First-principles prediction of vacancy order-disorder and intercalation battery voltages in LixCoO2

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 LixCoO2 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 LixCoO2/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.