Effects of manganese and cobalt on the electrochemical and thermal properties of layered Li[Ni0.52Co0.16+xMn0.32−x]O2 cathode materials

We investigate the effects of the Co and Mn ratio on the structure, morphology, electrochemical properties, and thermal stability of Li[Ni0.52Co0.16+xMn0.32−x]O2 cathode materials. Li[Ni0.52Co0.16+xMn0.32−x]O2 (x = 0, 0.08, 0.16) cathode materials are prepared via high temperature calcination of LiOH and coprecipitated [Ni0.52Co0.16+xMn0.32−x](OH)2 hydroxides. From an X-ray diffraction investigation, the prepared materials have a well ordered O3 type α-NaFeO2 layer structure (R3¯m). As the Co content (x) is increased, the initial discharge capacity increase slightly but it is accompanied by severe capacity fading during extensive cycling. Meanwhile, a small increase of Mn enhances the electrochemical stability at high temperature (55 °C) as well as the thermal stability. Electrochemical impedance spectroscopy reveals that manganese substitution is effective to reduce the resistance during cycling due to stabilization of the host structure.