Higher-energy-density batteries require higher capacity in the electrode, which motivates the increase of Ni in the NCM system. Nevertheless, fundamental effects of Ni element in the three-component layered system have not been 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 LiNi_0.5+xCo_0.2Mn_0.3-xO₂ (x = 0, 0.1, and 0.2) layered materials were 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 inter-slab thickness related to actual Li ion pathway. The inter-slab 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 de-intercalated states. Also, a higher Ni content material shows better structural properties such as larger inter-slab 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. More details will be discussed in the meeting.