Atomistic understanding of capacity loss in LiNiO₂ for high-nickel Li–ion batteries: First-principles study

Combining the first-principles calculations and structural enumeration with recognition, the delithiation process of LiNiO₂ is investigated, where various supercell shapes are considered in order to obtain the formation energy of Li_xNiO₂. Meanwhile, the voltage profile is simulated and the ordered phases of lithium vacancies corresponding to concentrations of 1/4, 2/5, 3/7, 1/2, 2/3, 3/4, 5/6, and 6/7 are predicted. To understand the capacity decay in the experiment during the charge/discharge cycles, deoxygenation and Li/Ni antisite defects are calculated, revealing that the chains of oxygen vacancies will be energetically preferrable. It can be inferred that in the absence of oxygen atom in high delithiate state, the diffusion of Ni atoms is facilitated and the formation of Li/Ni antisite is induced.