3D-Mixer-Assisted High-Entropy Doping of LiNiO₂ for Co-Free Ni-Rich Cathodes in Lithium-Ion Batteries

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 LiNiO₂ 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_1.05Ni(MnAlFeMgCr)_0.10O₂ 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.