Table 1. Summary of results.

Technique	Conclusion
HAADF STEM imaging	Spinel structure on the surface based on [010], [121] and [111] zone axes, some antisite defects in the spinel.
Core-loss EELS	O-edge signature and L3/L2 ratios indicate lower oxidation states of Mn and Co.
Li K edge/low-loss EELS	Li is present, but in lower concentration compared with the bulk. Li K edge indicates a spinel structure in the surface and layered in the bulk.
XEDS	Co and Ni segregation on the surface, Mn and O depletion.

EELS, electron energy loss spectroscopy; HAADF, high-angle annular dark field; STEM, scanning transmission electron microscopy; XEDS, X-ray energy-dispersive spectroscopy.