saturation concentration), reflecting the strong proclivity to Mn Ni -Ni Mn cation disorder in LMNO. Complexes (e.g. Mn Li -Li Mn ) with much lower predicted concentration contribute much less to the disorder. Since defect complex concentrations are higher in condition T than condition A, a greater range of disorder is induced by complex formation under O-poor conditions. In addition, there is a variable temperature-dependent entropic cost with complex formation, with higher defect concentrations corresponding to lower entropic costs of complex association. For example, V O,1 -V Li concentration is strongly dependent on temperature, whereas it is not the case for Ni Li -V Li . High synthesis/anneal temperatures will yield high point defect concentrations (Equation ), which then increasingly favour complex formation as the material cools to room temperature, but with the ability to equilibrate by migrating and forming complexes also decreasing with temperature. Thus the final defect distribution in the material is predicted to be sensitively dependent on the thermal history (i.e. synthesis, annealing and cooling procedures), as witnessed experimentally. 114