期刊
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
卷 56, 期 28, 页码 8178-8182出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/anie.201704324
关键词
ab initio calculations; electrochemistry; lithium bond; lithium-sulfur batteries; NMR spectroscopy
资金
- National Key Research and Development Program [2016YFA0202500, 2016YFA0200102]
- Natural Scientific Foundation of China [21676160, 21561130151]
- Tsinghua National Laboratory for Information Science and Technology
The lithium-sulfur (Li-S) battery is a promising high-energy-density storage system. The strong anchoring of intermediates is widely accepted to retard the shuttle of polysulfides in a working battery. However, the understanding of the intrinsic chemistry is still deficient. Inspired by the concept of hydrogen bond, herein we focus on the Li bond chemistry in Li-S batteries through sophisticated quantum chemical calculations, in combination with Li-7 nuclear magnetic resonance (NMR) spectroscopy. Identified as Li bond, the strong dipole-dipole interaction between Li polysulfides and Li-S cathode materials originates from the electron-rich donors (e.g., pyridinic nitrogen (pN)), and is enhanced by the inductive and conjugative effect of scaffold materials with pi-electrons (e.g., graphene). The chemical shift of Li polysulfides in Li-7 NMR spectroscopy, being both theoretically predicted and experimentally verified, is suggested to serve as a quantitative descriptor of Li bond strength. These theoretical insights were further proved by actual electrochemical tests. This work highlights the importance of Li bond chemistry in Li-S cell and provides a deep comprehension, which is helpful to the cathode materials rational design and practical applications of Li-S batteries.
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