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Structural Origin of the Superionic Na Conduction in Na2B10H10 Closo-borates and Enhanced Conductivity by Na Deficiency for High Performance Solid Electrolytes

Authors Lu, Ziheng HKUST affiliated (currently or previously)
Ciucci, Francesco View this author's profile
Issue Date 2016
Source Journal of Materials Chemistry A , v. 4, 2016, p. 17740-17748
Summary Recently reported superionic Na closo-borates have drawn considerable attention due to their potential as solid-state electrolytes for Na ion batteries. However, a fundamental understanding of the ion transport mechanism in these materials is still missing. We studied Na conduction in Na2B10H10, a model material, using first-principles calculations. We found that the superior Na diffusivity is closely linked to the behavior of the large B10H10 2- anionic groups. The reorientations and disorder of these groups facilitate the Na+ hopping to the octahedral (Oh) sites, which link the tetrahedral (Td) sites to form a connected diffusion network. We also found that, in spite of the frequent Na hopping events, the diffusional paths are often blocked, thereby hindering Na transport. Such a mechanism suggests that the Na conductivity can be improved by introducing extrinsic vacancies. By simulating Na-deficient systems, we found that at high temperatures, even a minimal amount of additional Na vacancies significantly increases the ionic diffusivity. © The Royal Society of Chemistry 2016.
ISSN 2050-7488
Language English
Format Article
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