The thermodynamic transition levels for the dominant intrinsic defects (a) and dopant species (b-f) calculated using the HSE06 functional at chemical potentials representative of the sintering temperature in air at 1200 • C are given in Figure . Based on the study by Squires et al. and an initial screening using PBEsol (transition levels given in SI Figure ), it can be seen that the formation energies of the Li Frenkel defect V ′ Li and Li • i , equation 8, are > 1 eV lower than all other intrinsic defects at the Fermi level (E F ), with the exception of V •• O and O ′′ i at very O poor or rich conditions respectively. As both Li and O defects dominate the defect chemistry in LLZO these were calculated using HSE06 in order to determine the effects of extrinsic doping. Our initial screening and calculations performed by Squires et al. [76] show a very small difference in formation energy (< 0.05 eV) between tetrahedrally and octahedrally coordinated V ′ Li . In spite of these results, our calculations using HSE06 result in notably larger differences in the formation energies of these defects. V ′ Li (32g) and V ′ Li (8a) possess very similar formation energies of ∼ 0.47 and ∼ 0.55 eV, respectively. However, the formation energy of V ′ Li (16f) is ∼ 0.76 eV, which is 0.29 eV higher than the formation energy of V ′ Li (32g) thus we expect a strong ordering of the V ′ Li defects at the sintering temperature. It can be proposed that this will result in larger migration barriers to and from the 16f sites than between the 8a and 32g sites. If one were to assume an increase in the migration barrier of ∼ 0.2 eV, (similar to