Preparation and electrochemical investigation of LiMn_(2-x)Me_xO_4 (Me: Ni, Fe, and x = 0.5, 1) cathode materials for secondary lithium batteries

摘要

The spinels LiMn_(1.5)Me_(0.5)O_4 and LiMnMeO_4 (Me: Ni, Fe) were prepared using either a sol-gel process in the case of nickel doping, or a solid-state reaction in the case of iron doping. X-ray diffraction analysis revealed differences in the patterns when the content of the dopant in the spinel increases. The pattern of LiMn_(1.5)Ni_(0.5)O_4 was indexed as a pure cubic spinel together with that of LiMn_(1.5)Fe_(0.5)O_4, whereas LiMnNiO_4 was found to be indexed mainly as a hexagonal layered phase since it was difficult to distinguish between these two structures because the diffraction peaks were broad. On the other hand, the pattern corresponding to LiMnFeO_4 was indexed as an inverse spinel.