Fig. 1.

(A) An expanded view of a Li-Me-O triangular phase diagram. Many cation ordered/disordered rocksalt phases (2) are located on a tie-line (solid blue line) between MeO and LiO. Li₃Nb⁵⁺O₄ is found on the tie-line and lithium content is highly enriched compared with those of LiMe³⁺O₂ and Li₂Me⁴⁺O₃. (B) Electrode performance of Li₃NbO₄ and a schematic illustration of the crystal structure of Li₃NbO₄. (Inset) A photograph of Li₃NbO₄ powder, which is an electrically insulating material.