The significance of the stable Rhombohedral structure in Li-rich cathodes for lithium-ion batteries
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- 作者：Yufang Chen ; Chunman Zheng ; Zhongxue Chen ; Kai Xie
- 关键词：Lithium ; rich compounds ; Aluminum doping ; Structural transformation ; Voltage decay ; Capacity fade
- 刊名：Ionics
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：23
- 期：2
- 页码：367-375
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Electrochemistry; Renewable and Green Energy; Optical and Electronic Materials; Condensed Matter Physics; Energy Storage;
- 出版者：Springer Berlin Heidelberg
- ISSN：1862-0760
- 卷排序：23
文摘
The lithium-rich layered oxides offer higher capacity, but suffer from severe capacity fade and voltage decay. Aluminum doping can improve the stability of the structure, but the fundamental mechanism has not been fully revealed. In this work, cathode materials with different Al-doping contents are investigated. To characterize the structural evolutions upon cycling, ex situ XRD and ex situ TEM are performed. It is demonstrated that the voltage decay is attributed to the decrease of Rhombohedral phase, while capacity fade is possibly associated with the increase of surface impedance. Therefore, continuous voltage decay and capacity fade are observed for undoped Li-rich cathode. In comparison, the Al-doped cathodes have stable LiNi1/3Co1/3Mn1/3O2 and surface impedance, leading to superior capacity retention and a stable output voltage.