X-ray diffraction and X-ray photoelectron spectroscopy analysis of Cr-doped spinel LiMn2O4 for lithium ion batteries

Cr-doped LiMn2O4 spinels were synthesized by a solid-state reaction. X-ray photoelectron spectroscopy (XPS) investigation shows the structural and valence changes of the Cr-doped LixMn2−yCrzO4 spinels with increasing Cr content. A conversion of Cr3+ to Cr6+ is found in the heavy-doped samples at 0.20<z<0.99. The further increase of z value results in the appearance of a second phase. The effects of Cr-doping on the structures and oxidation states are discussed.