The morphology of the single crystal fraction of particles is typical of literature reports, and extended faceting is visible on the 3D views of particles #1, #2 and #3 (Fig. ). Faceted surfaces are also observable for particles #4 and #6 despite presenting inner morphological defects and pores. Globally, the particles display irregular shapes, which do not reflect the hexagonal unit cell of the NMC structure. In addition to flat facets, many of the crystals have rounded edges, or even concavity. In order to illustrate this, a detailed study of the morphology of the isolated particles is presented in Figure . By looking at the 3D rendering of a large population of NMC particles, it is possible to appreciate the diversity of the shape distribution (Fig. ). Therefore, several mathematical criteria have been considered to precisely quantify their geometry: the ellipticity, the sphericity and the roundness (summarized in Fig. ). First, the 3D ellipticity represents the elongation along its three spatial axes of the ellipsoid that fits the particle :