Structural characterization of layered LiNi0.85−xMnxCo0.15O2 with x = 0, 0.1, 0.2 and 0.4 oxide electrodes for Li batteries

We report the synthesis of LiNi0.85−xCo0.15MnxO2 positive electrode materials from Ni0.85−xCo0.15Mnx(OH)2 and Li2CO3. XRD and XPS are used to study the effect of Mn-doping on the microstructures and oxidation states of the LiNi0.85−xCo0.15MnxO2 materials. The analysis shows that Mn-doping promotes the formation of a single phase. With increasing substitution of Mn ions for Ni ions, the lattice parameter a decreases, while the lattice parameters c and c/a increase. XPS revealed that the oxidation states of Ni, Co and Mn in LiNi0.85−xCo0.15MnxO2 compounds (where x = 0.1, 0.2 and 0.4) were +2/+3, +3 and +4. The substitution of Mn ions for Ni ions induces a decrease in the average oxidation state of Ni. Because the substitution of Mn for Ni ions is complex, the extent of the changes between the lattice parameter and LM–O differ. The occupation of Ni in Li sites is affected by the ordering of Mn4+ with Ni2+ and Mn4+ with Li+.