Figure 3

(Top). EDP of metastable mixed-valence-phase Li_2/3FePO₄. Green marks indicate the positions of the superstructure reflections. [−110]_Pnma (left) and [001]_Pnma (right) EDPs show a clear threefold superstructure in the ab plane of the original Pnma lattice. Reproduced with permission.³⁵ (Bottom) Annular bright-field (ABF) micrographs showing that the Li-ions occupy every other row in the partially delithiated LiFePO₄: (a) pristine material with the atomic structure of LiFePO₄; (b) fully charged state with the atomic structure of FePO₄, shown for comparison; and (c) half-charged state showing the Li staging. Note that Li sites are marked by yellow circles, whereas the delithiated sites are marked by orange circles. Reproduced with permission.³⁶