Equilibrium dopant concentrations, Table , and resulting V ′ Li concentrations, solid lines in Figure , have been calculated to better address the solubility of the different dopants as well as dopant concentrations from open system synthesis methods. These concentrations have been estimated from athermal defect formation energies at the dilute limit with the assumption of equilibrium, meaning that elements can freely be added to or removed from the system. Except for Y, typical dopant concentrations are >10 times higher than the equilibrium concentrations calculated herein. In for example solid state synthesis, only volatile elements such as Li can disappear from the system, and thus lower equilibrium concentrations than nominal concentrations imply that there is a driving force for the formation of secondary phases.