About the Thermodynamics of LixCoO2 in the Metal-Insulator Two-Phase Region Derived from DFT Calculations
Up to now this transition has never been modeled by ab initio calculations due to the lack of feasible straight-forward methods for strongly correlated materials to account for the interactions of the open-shell d-electrons as they exist in LixCoO2. In this work the ambition is to capture the 2-phase region by running a number of calculation series on various compositions within the 2-phase-region by using the GGA+U approach. The space of magnetic configurations is sampled and results are analyzed with respect to metallic and semiconducting properties. Convex hulls are drawn through the acquired data points in a total energy versus Lithium-concentration plot for the metallic and semiconducting states. The common tangent of both convex hulls will pinpoint the borders of the two-phase region.
The successful DFT-modeling of the metal-insulator transition is of particular interest since effects of dopants on this region could be studied. Especially the effect on the potential and the compositional range of the region would be leading aspects to look at since a higher potential and a broader two-phase region are beneficial for the cathode’s overall performance.