where g is the degeneracy of the defect and E f is the energy of defect formation. The formation energy itself is a function of the atomic chemical potentials µ i of the atoms involved in defect formation, and their electronic analog E F , the Fermi energy. In other words, the defect concentrations are a function of the thermodynamic regime under which defects form. In LiNiO 2 , the range of chemical potentials -that define the thermodynamic limits under which defect formation can occur before the system favors the formation of other phases -are narrow . This reflects the difficulties experienced in optimizing the synthesis of LiNiO 2 . We recalculate the chemical potential stability limits of LiNiO 2 , which are shown in fig. . This chemical potential region can generally be characterized as small-relative to, for example, LiCoO 2 -and lower metal chemical potential regions ("metal-poor") are coupled with high oxygen chemical potentials ("oxygen-rich"). Inclusion of the recently computationally predicted phase Li 2 Ni 2 O 3 marks a slight difference from the phase diagrams calculated previously under oxygen-poor metal-rich conditions, although in most respects it is qualitatively similar to previous studies .