Chemical obtaining of LiMO2 and LiM2O4 (M=Co, Mn) oxides, for cathodic applications in Li-ion batteries

Abstract

This paper describes the synthesis and characterization of two spinel and olivine-type multicomponent oxides based on LiMO₂ and LiM₂O₄ systems (M=Co and Mn), which represent the current state of the art in the development of cathodes for Li-ion batteries. A simple combustion synthesis process was employed to obtain the nanometric oxides in powder form (crystal sizes around 5-8nm), with a number of improved surface characteristics. The characterization by X-Ray Diffraction (XRD), Scanning and Transmission Electron Microscopy (SEM, TEM) and X-Ray Fluorescence (XRF), allowed to evaluate the morphology and the stoichiometric compositions of solids, obtaining a concordant pure crystalline phase of LiCoO₂ and LiMn₂O₄ oxides identified in a rhombohedral and cubic phase with punctual group R-3m (1 6 6) and Fm-3m (2 2 5) respectively. The electrical characterization of materials developed by impedance spectroscopy solid state, allowed to determine a p-type semiconducting behaviour with conductivity values of 6.2×10^-3 and 2.7×10^-7 S for LiCoO₂ and LiMn₂O₄ systems, consistent with the state of the art for such materials.