期刊
ADVANCED SCIENCE
卷 7, 期 22, 页码 -出版社
WILEY
DOI: 10.1002/advs.202002358
关键词
Cu3Ge; Ge heterostructures; cycling stability; Germanium; sodium-ion batteries; structural integrity
资金
- Natural Science Foundation of Guangdong Province [2018A030313739]
- Xijiang RD Team
- Guangdong Innovative and Entrepreneurial Team Program [2016ZT06C517]
- University of Waterloo
- Natural Science and Engineering Research Council of Canada
- Guangdong Provincial Grant [2017A050506009]
Germanium (Ge)-based materials have been considered as potential anode materials for sodium-ion batteries owing to their high theoretical specific capacity. However, the poor conductivity and Na(+)diffusivity of Ge-based materials result in retardant ion/electron transportation and insufficient sodium storage efficiency, leading to sluggish reaction kinetics. To intrinsically maximize the sodium storage capability of Ge, the nitrogen doped carbon-coated Cu3Ge/Ge heterostructure material (Cu3Ge/Ge@N-C) is developed for enhanced sodium storage. The pod-like structure of Cu3Ge/Ge@N-C exposes numerous active surface to shorten ion transportation pathway while the uniform encapsulation of carbon shell improves the electron transportation, leading to enhanced reaction kinetics. Theoretical calculation reveals that Cu3Ge/Ge heterostructure can offer decent electron conduction and lower the Na(+)diffusion barrier, which further promotes Ge alloying reaction and improves its sodium storage capability close to its theoretical value. In addition, the uniform encapsulation of nitrogen-doped carbon on Cu3Ge/Ge heterostructure material efficiently alleviates its volume expansion and prevents its decomposition, further ensuring its structural integrity upon cycling. Attributed to these unique superiorities, the as-prepared Cu3Ge/Ge@N-C electrode demonstrates admirable discharge capacity, outstanding rate capability and prolonged cycle lifespan (178 mAh g(-1)at 4.0 A g(-1)after 4000 cycles).
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