The convex hull shown in Figure was constructed by calculating all the unique configurations of delithiated structures over all the Li content in a 2 × 2 × 1 supercell with four formula units of To verify the existence of the layered LiNi 2 O 3 structure, we performed AIRSS search on this mixvalent composition. This structure, which exists in the P3 " m1 space group, was encountered by AIRSS. Figure shows it is at a local energy minimum. Interestingly, the lowest energy structure with the LiNi 2 O 3 composition is not the P3 " m1 LiNi 2 O 3 , and the energy difference between the P3 " m1 LiNi 2 O 3 and the lowest energy Immm LiNi 2 O 3 structure is 27.63 meV atom -1 .