Alkali-Metal Modification of Li(Ni0.33Mn0.33Co0.33)O2*

Layered lithium transition metal oxides are widely used as cathodes in lithium-ion batteries and are continuously being developed to provide more energy. Here, the synthesis and structure of Li(Ni0.33Mn0.33Co0.33)O2, ‘Li0.9K0.1(Ni0.33Mn0.33Co0.33)O2’, and ‘Li0.9Cs0.1(Ni0.33Mn0.33Co0.33)O2’ are characterised in detail and compared with similar studies in the literature. Structural models are evaluated based on the statistical quality of fitting via the Rietveld method with X-ray diffraction data and the use of a range of starting structural models. Critically, this work highlights that the larger alkali atoms do not dope on to the Li sites but rather are likely to be distributed on the surface of the particles which is also evidenced with electron microscopy. This work showcases that care must be taken by researchers when using such doping regimes and the concentration of the dopants.