The stoichiometric complexes have identical density of the available microstates (N states = 4.40 ×10 22 cm -3 ), the differences in the calculated complex concentrations therefore arise from the concentrations of their constituent point defects. For instance, under condition T (Figure ), [Mn Li -Li Mn ] is lower than [Ni Li -Li Ni ] at the majority of temperature range despite that they have similar ∆E crit and that ∆H for Mn Li -Li Mn is highly negative (see Figure ). Although complex formation is more favourable at lower temperature, this requires isolated point defects to "find" each other. Point defects with high mobility -such as lithium vacancies and interstitials-and/or those that with high concentration are likely to achieve this criterion. Mn Ni -Ni Mn has the highest concentration for maximum (>99%) complex formation (i.e.