Rare-Earth Doping Induced Pinning Effect with Enhanced Chemo-Mechanical Stability in Ni-Rich Cathodes for Lithium-Ion Batteries

The nickel-rich layered ternary cathode material (NCM) has been extensively studied due to its high specific capacity and low cost. Nevertheless, with the increase of Ni content, the unstable structure of NCM material has gradually become prominent. Residual alkali on the surface and Li⁺/Ni²⁺ mixing before cycling, phase change, transition metal ions dissolution, microcracking, and other issues during the cycle, are the primary causes for the fast capacity fading of Ni-rich materials. In this study, Sc³⁺ is doped into the LiNi_0.8Co_0.1Mn_0.1O₂ material, which has been demonstrated to impede the Li⁺/Ni²⁺ mixing, while simultaneously increasing the layer spacing. This results in the stabilization of the material structure and an enhancement of both the cycling stability and the rate performance. Notably, single-particle force testing and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging further demonstrate reduced stress accumulation and mitigated chemo-mechanical failure. This study underscores the efficacy of a minor addition of multifunctional rare-earth doping in enhancing the chemo-mechanical stability of Ni-rich cathodes, offering a straightforward and comprehensive solution to optimize the design and performance of energy storage cathodes.