Fig. 1: Structural and chemical characterization of the pristine valence gradient NMC811 material (VG-NMC811).
From: Hierarchical nickel valence gradient stabilizes high-nickel content layered cathode materials
a Rietveld refinement of pristine VG-NMC811. b X-ray fluorescence quantitative mapping of Ni, Mn, and Co showing uniform transition metal distribution across the whole secondary particle. c High-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) images of a cross-sectional slice of VG-NMC811 secondary particle prepared by focused ion beam (FIB). d STEM-energy-dispersive X-ray spectroscopy (EDs) quantitative mapping of Ni. e The electron energy loss spectra (EELS) of Ni L2,3-edge across the surface and the center. f The Ni2+ and Ni3+ concentrations along the line profile extracted from spectra in (e). g The EELS spectra of Mn L-edge and Co L-edge integrated in the four squared regions in (c).
