Concentration-Gradient Nb-Doping in a Single-Crystal LiNi0.83Co0.12Mn0.05O2 Cathode for High-Rate and Long-Cycle Lithium-Ion Batteries

• Published in: ACS applied materials & interfaces 2023-04, Vol.15 (15), p.18828-18835
• Main Authors: Wu, Hai, Zhou, Xing, Yang, Chao, Xu, Dawei, Zhu, Yu-Hui, Zhou, Tengfei, Xin, Sen, You, Ya
• Format: Article
• Language: English
• Subjects: Energy, Environmental, and Catalysis Applications
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.2c23076

Single-crystalline nickel-rich layered oxides are promising cathode materials for building high-energy lithium-ion batteries because of alleviated particle cracking and irreversible phase transitions upon cycling, compared with their polycrystalline counterparts. Under a high state of charge, parasitic reactions tend to occur at the cathode–electrolyte interface, which could result in sluggish Li-ion diffusion kinetics and quickly faded electrochemical performance of cathodes. In this work, a concentration-gradient niobium-doping strategy was applied to modify the single-crystal LiNi0.83Co0.12Mn0.05O2 cathode, with Nb concentration decreasing linearly from the surface to the core of the particle. As a result, the Nb-rich surface functions as an electrochemically active protective layer against electrolyte corrosion and transition metal dissolution, while the Nb-deficient core contributes to a higher capacity. The linear concentration gradient also minimizes structural transition from the surface to the core and helps to maintain structural integrity during repeated Li (de)­intercalation. In addition, Nb-doping also assists to alleviate Li+/Ni2+ mixing and increases the interlayer distance to enable faster Li-ion diffusion kinetics. By taking these advantages, the Nb-doped cathode materials (containing 1.0 atom% Nb) demonstrate a high reversible capacity, a high capacity retention, and improved rate capabilities. This work provides a general and facile approach to improve the storage performance of layered-oxide cathode materials by rationally tuning the bulk structure and interface with the electrolyte.