Understanding the role of Co in the Ni-rich cathode materials for Li-ion batteries

Layered Ni-rich compounds are considered to be the most promising cathode materials for Li-ion batteries due to high energy density. However, the high cost constrains their wider commercial application. In order to reduce the cost of Ni-rich cathodes, substituting Co with other abundant and cheap metals is considered to be an effective strategy. To develop reasonable substitution strategies, the role of Co in the Ni-rich cathode materials is studied based on first-principles calculations in present work. It is found that Co is beneficial to improve the cycle performance and electronic conductivity of Ni-rich cathode materials and to suppress Li/Ni disorder. However, Co will promote the release of oxygen in the Ni-rich cathode. These findings provide a theoretical basis for developing substitution strategies of Co and promote the design of low-cost Ni-rich cathode materials.Graphical abstract