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

Abstract A study of the LiNi 1− x − y Co x Mn y O 2 ( 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- 3 m 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 Ni 2+ , Co 3+ and Mn 4+ . However, the Ni2p 3/2 and Co2p 3/2 binding energy increases versus Ni content, indicating the increased Me O bond covalency. The highest specific discharge capacity was observed for LiNi 0.6 Co 0.2 Mn 0.2 O 2 —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.