First-Principles Prediction of Vacancy Order-Disorder and Intercalation Battery Voltages inLixCoO2

Abstract

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 ${\mathrm{Li}}_x{\mathrm{CoO}}_2$ 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 ${\mathrm{Li}}_x{\mathrm{CoO}}_2/\mathrm{Li}$ 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.