New Insight into Ni‐Rich Layered Structure for Next‐Generation Li Rechargeable Batteries

An increase in the amount of nickel in LiMO2 (M = Ni, Co, Mn) layered system is actively pursued in lithium-ion batteries to achieve higher capacity. Nevertheless, fundamental effects of Ni element in the three-component layered system are not systematically studied. Therefore, to unravel the role of Ni as a major contributor to the structural and electrochemical properties of Ni-rich materials, Co-fixed LiNi0.5+xCo0.2Mn0.3-xO2 (x = 0, 0.1, and 0.2) layered materials are investigated. The results, on the basis of synchrotron-based characterization techniques, present a decreasing trend of Ni2+ content in Li layer with increasing total Ni contents. Moreover, it is discovered that the c(hex.)-lattice parameter of layered system is not in close connection with the interslab thickness related to actual Li ion pathway. The interslab thickness increases with increasing Ni concentration even though the c(hex.)-lattice parameter decreases. Furthermore, the lithium ion pathway is preserved in spite of the fact that the c-axis is collapsed at highly deintercalated states. Also, a higher Ni content material shows better structural properties such as larger interslab thickness, lower cation disorder, and smoother phase transition, resulting in better electrochemical properties including higher Li diffusivity and lower overpotential when comparing materials with lower Ni content.