期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 141, 期 49, 页码 19360-19372出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.9b09343
关键词
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资金
- Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub - U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences
- NSERC
- National Natural Science Foundation of China [21773081, 21533003]
- Talents Cultivation Program (Jilin University, China)
- Compute Canada
Single-ion conducting solid electrolytes are gaining tremendous attention as essential materials for solid-state batteries, but a comprehensive understanding of the factors that dictate high ion mobility remains elusive. Here, for the first time, we use a combination of the Maximum Entropy Method analysis of room-temperature neutron powder diffraction data, ab initio molecular dynamics, and joint-time correlation analysis to demonstrate that the dynamic response of the anion framework plays a significant role in the new class of fast ion conductors, Na(11)Sn(2)PnX(12) (Pn = P, Sb; X = S, Se). Facile [PX4](3-) anion rotation exists in superionic Na11Sn2PS12 and Na11Sn2PSe12, but greatly hindered [SbS4](3-) rotational dynamics are observed in their less conductive analogue, Na11Sn2SbS12. Along with introducing dynamic frustration in the energy landscape, the fluctuation caused by [PX4](3-) anion rotation is firmly proved to couple to and facilitate long-range cation mobility, by transiently widening the bottlenecks for Nation diffusion. The combined analysis described here resolves the role of the long-debated paddle-wheel mechanism, and is the first direct evidence that anion rotation significantly enhances cation migration in rotor phases. The joint-time correlation analysis developed in our work can be broadly applied to analyze coupled cation-anion interplay where traditional transition state theory does not apply. These findings deliver important insights into the fundamentals of ion transport in solid electrolytes. Invoking anion rotational dynamics provides a vital strategy to enhance cation conductivity and serves as an additional and universal design principle for fast ion conductors.
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