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 degrees 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.