Given the low formation energies and thus high concentrations of cation antisites, lithium and oxygen vacancies, we further investigate the association of point defects, including three stoichiometric (antisite-pairs), and eight non-stoichiometric (vacancy-related) complexes. Since the formation energy on the oxygen vacancy in 24e sites (O 1 ) is always lower and O 1 has higher multiplicity than O 2 (in the 8c sites), we only conduct detailed analysis on the association of V Li with V O,1 . Figure shows defect complex association energies ∆H calculated following Equation over 20 chemical potential limits at their self-consistent Fermi levels. ∆H for a given complex can vary with chemical potentials, even for stoichiometric complexes, due to the indirect effect on the charge-balanced Fermi level. A negative ∆H indicates an exothermic enthalpy change upon defect association. The majority of complexes have negative ∆H, and they feature point defects coulombically attracted to each other. The few complexes that feature defects of the same charge (i.e. both p-type defects) are coulombically opposed to each other, and hence have positive ∆H (e.g. Li Ni -V Li ). Using ∆H alone to evaluate complex formation, however, neglects a key factor -the temperature dependent entropic cost of defect association. The actual formation of a defect complex and its concentration are influenced by a range of factors, including temperature, concentrations of the constituent defects and ∆H. We considered the entropic effects in this study by approximating the entropic term using Equation , where lower defect concentrations and higher temperatures correspond to larger entropic costs for association into defect complexes. Correspondingly, Figure shows how ∆G increases with temperature, suggesting complex formation is sensitive to kinetic behaviour during synthesis and quenching. ∆G are generally more negative in the n-type condition than p-type, suggesting that there is a stronger driving force towards complex association even at high temperature in O-poor conditions. Figure shows the approximated temperature-dependent entropic cost (calculated using Equation ) for defect complexes with negative ∆G. A high degree of association is achieved when the complex association energy magnitude |∆H| is greater than ∆E crit , showing that one cannot use ∆H alone to evaluate complex formation. For example, under the intrinsically p-type environment (Figure ), the Mn Li -Li Mn association energy |∆H| = 0.4 eV is only sufficient to achieve a high degree of association at 500 K but not at 900 K. Increased entropic cost of complex formation is observed for defects with lower concentration (see Figure ).