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

摘要

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)]O_4 (0.0 <=x <=0.333) using the stoichiometry mixtures of lithium acetate and manganese nitrate as starting materials. The crystal structure of these compounds wwas studied with Rietveld refinements of the X-ray diffraction profiles. The lattice parameter of the spinels shows a strong dependence of the comosition 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 mu m, depending on the synthesis conditions. Samples with x<=0.125 show good electrode performance for the cell Li/Li_(1+x)Mn_(2-x)O_4 in the 4V region, whereas Li_4Mn_5O_(12) (x chemical bounds 0.333) spinels show good cyclability with a fechargeable capacity of over 100mAh/g in the 3V region.