Novel synthesis process and characterization of Li-Mn-O spinels for rechargeable lithium batteries

A new process has been developed for the synthesis of well-crystallized Li-Mn-O spinels with a homogeneous composition Li[Li_xMn_2-x]O₄ (0.0≤x≤0.333) using the stoichiometry mixtures of lithium acetate and manganese nitrate as starting materials. The crystal structure of these compounds was studied with Rietveld refinements of the X-ray diffraction profiles. The lattice parameter of the spinels shows a strong dependence on the composition and manganese oxidation state. SEM micrographs indicate that the crystallites appear as single crystals. The size of the crystallites are in the range of 0.1-2 μm, depending on the synthesis conditions. Samples with x≤0.125 show good electrode performance for the cell Li/Li_1+xMn_2-xO₄ in the 4 V region, whereas Li₄Mn₅O₁₂ (x = 0.333) spinels show good cyclability with a rechargeable capacity of over 100 mAh/g in the 3 V region.