Doping Strategy in Developing Ni-Rich Cathodes for High-Performance Lithium-Ion Batteries

Doping is indispensable for ensuring the long-term cycling stability of the Ni-rich layered cathodes. However, using a single type of dopant limits the development of a stable, high-energy cathode material in a single shot. In this study, a dual doping strategy using Al³⁺ and Nb⁵⁺ ions was adopted to improve the cycling stability of Li[Ni_0.92Co_0.04Mn_0.04]O₂ (NCM92) cathode; Al³⁺ doping fortifies the crystal structure, while Nb⁵⁺ doping optimized the morphology of the primary particles. The dual doping strategy not only combines the benefits of both dopants simultaneously but also demonstrates excellent performance enhancement through synergistic effects. The Li[Ni_0.905Co_0.04Mn_0.04Al_0.005Nb_0.01]O₂ (AlNb-NCM92) cathode, which was developed through the dual doping of Al and Nb, exhibited remarkable stability, retaining 88.3% of its initial capacity even after 1000 cycles. This result suggests that the doping strategy needs to comprehensively consider both the crystal structure and the microstructure to maximize the long-term cycling stability of high-energy Ni-rich cathode materials.