Capacity fading of high specific capacity spinel Li x Mn 2-y Ti y O 4 as cathode material for Li-ion batteries

A facile sol–gel method is presented and used to optimize Li x Mn 2-y Ti y O 4 spinel-type materials for Li-ion battery cathodes while maintaining nanostructured features and minimizing the formation of TiO 2 impurities. LiMn 1.8 Ti 0.2 O 4 exhibited the best initial specific capacity of 215 mA h g −1 at 30.8 mA g −1 in a window potential of 4.6 – 2.0 V vs. Li|Li + . The addition of Ti improved the specific capacity thanks to possibility of using both Mn 4+ |Mn 3+ and Mn 3+ |Mn 2+ transitions. However, capacity fading issues persist. The effect of Ti incorporation and degradation processes during cycling were studied by cyclic voltammetry, charge/discharge cycling and EIS, the latter was analyzed by seldom used distribution of relaxations times (DRT) and compared to the results obtained by fitting to equivalent electrical circuits. Cathode materials were characterized by XPS, Raman and BET surface area and at different cycling stages by XRD, Synchrotron XRD and SEM. The results showed undesired structure modifications for the transition Mn 3+ |Mn 2+ and the formation of irreversible tetragonal phase that increased charge transfer resistances. Graphic abstract