Diffusion of Zirconium (IV) Ions from Coated Thick Zirconium Oxide Shell to the Bulk Structure of Ni‐Rich NMC811 Cathode Leading to High‐Performance 18650 Cylindrical Li‐Ion Batteries

Herein, Ni‐rich LiNi0.8Mn0.1Co0.1O2 or NMC811 cathode material, which is expected to be widely used soon, is coated by crystalline ZrO2 nanoparticles using green and scalable mechanofusion technique with an annealing process. A controllable synergistic effect of ZrO2 coating, as a spherical core–shell morphology with low surface energy, which is ideal for the process of electrode fabrication, and Zr4+ doping is carefully investigated. For the first time, the mechanofusion with the post‐annealing at 800 °C used in this work can finely tune the shell thickness and doping gradient by the diffusion of Zr4+ from the coated ZrO2 shell to the bulk structure of NMC811. The optimized material, namely NMC@Zr‐800 used as the cathode of 18650 cylindrical Li‐ion batteries (LIBs), can provide excellent capacity retention over 1000 cycles at a severe 100% state‐of‐charge (SOC) at 1.0 C. Postmortem analysis shows that the material is stable with less crack formation and transition metal (TM) dissolution than the pristine NMC811 material owing to a synergistic effect of the surface protection by ZrO2 coating and Zr4+ doping. The results demonstrate the practical and scalable approach that will be beneficial for technological advancement in the high‐energy 18650 cylindrical LIBs.