Effects of Cation Ordering in Concentration-Gradient NCM811 Structures from First-Principles Calculations

The Ni-Co-Mn ternary cathode material LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) for lithium-ion batteries has garnered significant interest because of its outstanding comprehensive performance. The increase in Ni content in the material causes a considerable reduction in battery capacity and leads to cation disorder during charge/discharge. Herein, the models of NCM811 with concentration-gradient structures are constructed through the design of the concentration gradient and the adjustment of the arrangement of the cations in the transition-metal layer. Using density functional theory and first-principles calculations, the parameters of LiNiO₂ and cation-ordered concentration-gradient NCM811 structures are discussed, and we have found the concentration-gradient design can effectively improve the electrochemical and mechanical properties of NCM811. In particular, NCM811 with randomly arranged Mn cations in the transition-metal layer exhibits good electric conductivity and ductility. The design of the concentration gradient is a promising approach for the development of high-performance layered cathode materials for lithium-ion batteries.