3D‐Mixer‐Assisted High‐Entropy Doping of LiNiO ₂ for Co‐Free Ni‐Rich Cathodes in Lithium‐Ion Batteries

ABSTRACT The development of Co‐free, Ni‐rich cathodes is critical to overcoming cost and sustainability challenges in lithium‐ion batteries. Here, we propose a high‐entropy doping strategy for LiNiO ₂ by uniformly incorporating Mn, Al, Fe, Mg, and Cr into the transition‐metal layer through a scalable 3D mixing process. Each dopant plays a complementary role in stabilizing the layered structure and enhancing electrochemical performance. The resulting Li _1.05 Ni(MnAlFeMgCr) _0.10 O ₂ suppresses Li/Ni cation mixing, strengthens TM─O bonding, mitigates polarization and diffusion bottlenecks, and reduces electrode swelling (from 23% in pristine LNO to 16%). The high‐entropy‐doped cathode delivered a capacity retention of 79% after 100 charge–discharge cycles at 0.3 C, markedly surpassing that of pristine LNO (51%). These results demonstrate that high‐entropy doping effectively improves structural robustness and long‐term durability, offering a practical pathway to economically viable and sustainable next‐generation Co‐free Ni‐rich layered cathodes.