2.3. Characterizations Crystallographic structures of bare NCM811 and Al2O3-coated NCM811 materials were examined by X-ray diffraction (XRD), using a Bruker D8 Advance automatic diffractometer (Bruker, Billerica, Coatings 2019, 9, 92 4 of 12 MA, USA) with Cu Kα radiation. Morphologies and ...