Co/Mn distribution and electrochemical intercalation of Li into Li[Mn2−yCoy]O4 spinels, 0<y≤1

Single-phase oxides with Li[Mn2−yCoy]O4 (0≤y≤1) stoichiometry and cubic spinel structure have been prepared by using the lactate precursor method. The oxides were alternatively quenched or slow cooled from 750°C. X-ray diffraction and EPR spectroscopy show that Co and Mn are disordered over 16d spinel sites for samples obtained by air quenching. Local environment of Mn4+ was assessed by comparison of the observed EPR spectra for Li[Mn2−yCoy]O4 compositions with the EPR signal from Mn4+ in LiMnCoO4 and the EPR spectrum of LiMn2O4. Thus, a local Co/Mn ordering is found for spinels obtained by slow-cooling. The use of these materials as the cathodic active compound in lithium cells reveals a higher capacity but lower capacity retention in the 3–4 V regions for metal-quenched samples as compared with slow-cooled products.