Synergy of doping and coating induced heterogeneous structure and concentration gradient in Ni-rich cathode for enhanced electrochemical performance

• Published in: Journal of power sources Vol. 423; pp. 144 - 151
• Main Authors: Li, Yong-Chun, Xiang, Wei, Xiao, Yao, Wu, Zhen-Guo, Xu, Chun-Liu, Xu, Wei, Xu, Ya-Di, Wu, Chen, Yang, Zu-Guang, Guo, Xiao-Dong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31-05-2019
• Subjects: Coating; Doping; Gradient concentration; Heterogeneous structure; Ni-rich cathode; Ni-rich cathode; Coating; Heterogeneous structure; Gradient concentration; Doping
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2019.03.073

Structural instability and inferior storage property are bottlenecks of the Ni-rich cathodes. Herein, a coating and doping co-modified Ni-rich cathode, in which La and Al is homogeneously doped in the inner and an epitaxial layer is distributed in the outer surface region of secondary particle, is constructed. The outer surface layer tightly integrates a La2O3 coating layer, an epitaxial grown LaAl doped atomic structure and a Ni concentration gradient into the bulk phase. The La and Al act as a pillar ion enlarging c axis spacing and a positively charged center, enhancing Li+ transportation and suppressing the phase transition. The outer surface region with La-enriched layer and decreased Ni concentration suppresses the side reactions between organic electrolyte and oxidizing Ni4+ and improves the storage stability in air. During cycling, the modified material exhibits enhanced rate capability and cycling stability with capacity retention of 80.0% after 480 cycles at 10C in the cell potential range of 2.7–4.3 V.
[Display omitted]
•Ni-rich cathode is modified with synergy of coating and doping by La and Al.•Lower lattice expansion and higher Li+ transportation due to La doping.•The coating layer suppresses erosion of electrolyte and improve storage stability.