Vacancy Ordering in O3 -Type Layered Metal Oxide Sodium-Ion Battery Cathodes

To improve battery technology, cathodes based on intercalated Na${}^{+}$ rather than Li${}^{+}$ are closely studied, as sodium is much cheaper, and sodium-ion batteries can be fully drained yet still remain viable. Unfortunately, during cycling Na cathode materials present reversible vacancy-ordering phase transformations that can reduce performance. The authors use high-throughput calculations to study the nature of these transformations in all known Na${}_{x}$$M$O${}_{2}$ layered compounds, and their findings may also apply to systems with other alkali ions.