Optimization of Ni2+/Ni3+ ratio in layered Li(Ni,Mn,Co)O2 cathodes for better electrochemistry

A study of the LiNi1−x−yCoxMnyO2 (x = y = 0.1; 0.2; 0.33) cathode materials prepared from mixed hydroxides and LiOH using the method of mechanical activation has been performed. All as prepared materials were indexed in the R-3m space group. The cell volume and the degree of structural disordering decrease with reducing of Ni content. According to XPS study, the main electronic state of d-ions in the surface layer of particles corresponds to Ni2+, Co3+ and Mn4+.However, the Ni2p3/2 and Co2p3/2 binding energy increases versus Ni content, indicating the increased Me O bond covalency. The highest specific discharge capacity was observed for LiNi0.6Co0.2Mn0.2O2—170 mAh g−1. The position of redox peaks on the differential capacity curves depends on the composition of the sample: it shifts towards lower voltage with increased Ni content.