期刊
ADVANCED ENERGY MATERIALS
卷 12, 期 20, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/aenm.202200813
关键词
dual gradient; high voltage; LiCoO; (2) cathodes; lithium-ion batteries; stable surface structure
类别
资金
- National Natural Science Foundation of China [52172175]
- Shenzhen Science and Technology Research Grant [JCYJ20200109140416788, JCYJ20210324130812033]
- Chemistry and Chemical Engineering Guangdong Laboratory [1922018]
- National Key R&D Program of China [2020YFB0704500]
- Major Science and Technology Infrastructure Project of Material Genome Big-science Facilities Platform - Municipal Development and Reform Commission of Shenzhen
In this study, a new strategy called cation and anion dual gradients at the surface of LiCoO2 (DG-LCO) was proposed to minimize the highly oxidized species and improve the cycling stability and rate capability of LCO as cathode material for lithium-ion batteries.
LiCoO2 (LCO) is the most successful cathode material for commercial lithium-ion batteries. Cycling LCO to high potentials up to 4.5 V or even 4.6 V can significantly elevate the capacity but cause structural degradation due to the serious surface side reaction between the highly oxidized Co4+ and O- species with organic electrolytes. To tackle this concern, a new strategy, constructing cation and anion dual gradients at the surface of LCO (DG-LCO), is proposed. Specifically, the electrochemically inactive cation and anion are selected to substitute Co3+ and O2- at the surface in a gradated manner, thus minimizing the highly oxidized Co4+ and O- species at high potentials and suppressing the induced surface side reactions. Unexpectedly, this dual gradient design leads to a spinel-like surface structure coherently with bulk layered structure, which facilitates Li+ diffusion kinetics. Thus, DG-LCO achieves high capacity and excellent cycling stability at 4.6 V (approximate to 216 mA h g(-1) at 0.1 C, a capacity retention of 88.6% after 100 cycles in 1.8 A h pouch full cell at 1 C), as well as improved rate capability (approximate to 140 mA h g(-1) at 5 C). These studies provide useful guidelines for future design of cathode materials with long lifespan and high rate capability.
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