Embracing cation disorder enables the use of novel cathode chemistries that do not need to maintain a layered ordering on cycling . The performance of any intercalation cathode is limited by the ability of lithium to reversibly intercalate into the host framework which is dependent on atomistic diffusion processes. Figure illustrates a cubic close-packed oxygen lattice. In both the layered and disordered systems lithium diffusion occurs from an octahedral hole in the O 2-framework via an octahedral face, into an interstitial tetrahedron. The diffusing ion then occupies a new octahedral site via another shared octahedraltetrahedral face (an "oct-tet-oct" hop) . The energy barrier for lithium hopping is then strongly influenced by the stability of lithium in the tetrahedral hole . The stability of lithium in this tetrahedral transition state depends on factors such as the identity of the facesharing cations: too many face-sharing transition metals destabilises the lithium in the tetrahedral transition state increasing the energy barrier for lithium diffusion . In disordered rock salt cathodes a percolating network of lithium sites connected by tetrahedral holes with no face-sharing transition metals (referred to as "0-TM" sites) is generally found to be necessary for effective long-range diffusion . The pathway for single-ion lithium hopping and a range of potential transition state local environments in disordered rock salts are shown as a 2D schematic in Figure .