The only case where the simple "lithium-only" defect model gives approximate agreement with the full model, with respect to the change in concentrations of charge-carrying lithium defect species, is for supervalent doping under Li-poor synthesis conditions (fig. ). In this case, the lowest formation energy negatively-charged defect species in the undoped system is the lithium vacancy, which therefore shows the strongest enhancement in concentration under supervalent doping. Under Li-poor conditions, the dominant negatively-charged defect species in the undoped system is the oxygen-chlorine O Cl antisite, which is now preferentially enhanced by supervalent doping. This suppresses the increase in lithium vacancy concentration relative to that predicted by the simple "lithium-only" model.