Role of transition metals in a charge transfer mechanism and oxygen removal in LiNiMnCoO: experimental and first-principles analysis

Oxygen removal from high capacity Li-rich layered oxide Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 O 2 affects the charge transfer process during cycling. During de-lithiation, oxygen removal takes place with the reduction in oxygen binding energy. Co substitution affects oxygen removal by shifting the O-p orbital closer to the Fermi energy. A convex hull plot is used to analyse single-phase and two-phase reactions during de-lithiation in Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 O 2 and Li 2 MnO 3 . Experimentally, the single-phase and two-phase reactions are identified based on the characteristics of the charge curve. In the charge transfer process more than 80% of lithium charge is transferred to oxygen in both the compounds. Effective charge and cyclic voltammetry reveal the redox centers in the compounds which help to understand the role of oxygen and transition metals in de-lithiation. A detailed explanation of oxygen removal and the charge transfer mechanism of Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 O 2 and Li 2 MnO 3 is provided in the current experimental and density functional theory based study. First principles calculations based on density functional theory were performed to understand the charge transfer mechanism and oxygen binding energy in Li 1.17 Ni 0.17 Mn 0.5 Co 0.17 O 2 .