The host material is thermodynamically stable and there are 20 intersection points bounding the stability region in the chemical potential space. Each intersection point corresponds to a facet in the phase diagram where the corresponding phases are in equilibria with the host (see Table ). O-rich (µ O = 0 eV) oxidizing conditions are usually Mn-and Ni-poor, and favour p-type (acceptor) defect formation. O-poor, Mn-and Ni-rich reducing conditions favour n-type behaviour, which can occur under higher temperature and/or reduced oxygen partial pressure and/or under the presence of oxygen-reducing agents (e.g. LiH). The quaternary phase space of LMNO yields a 4D stability region, thus to allow visualisation on a 2D plot, we show in Figure the stability region where µ Li and µ Mn were set to the average values over all atomic chemical potentials intersection points. LMNO is stable across a small µ Ni range, a moderate µ Li range and a larger µ Mn range. The size of the stability field reflects the ease of synthesizing the target product experimentally and determines the range of variation in defect formation energy over all possible growth conditions. Thus, there is a greater sensitivity of defect concentrations to Mn-related than Ni-related growth environments. The ease of nickel oxide impurity phase formation upon synthesizing LMNO is reflected by the the small µ Ni window. 12,61 . In addition, the potential formation of peroxide species from oxygen interstitials was tested by placing O i at distances ∼ 1.4 Å from O host and relaxing the defect geometry from this structure. We also considered a range defect complexes including the antisite-pair defects (Li Mn -Mn Li , Li Ni -Ni Li and Mn Ni -Ni Mn ), vacancy-pair (Schottky) defects (e.g. V O -V Li , Mn Ni -V Li ) and a lithium