Stable Crystalline Forms of Na Polysulfides: Experiment versus Ab Initio Computational Prediction

For the design of light‐metal–sulfur batteries and for the understanding of their performance, knowledge on the stable crystalline polysulfides is very important. We confronted experimental and ab initio crystal structure prediction studies on the stability of Na polysulfides. The selected evolution...

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Bibliographic Details
Published in:Chemistry : a European journal 2016-03, Vol.22 (10), p.3355-3360
Main Authors: Mali, Gregor, Patel, Manu U. M., Mazaj, Matjaž, Dominko, Robert
Format: Article
Language:English
Subjects:
ab initio calculations
Algorithms
Chains
Chemistry
Computer applications
Constants
Coupling
Crystal structure
crystal-structure predictions
Design
Evolutionary algorithms
Light effects
Magnetic resonance spectroscopy
Mathematical analysis
Metals
NMR
NMR spectroscopy
Nuclear magnetic resonance
Polysulfides
Sodium
Sodium sulfur batteries
solid-state NMR spectroscopy
Spectroscopic analysis
Spectrum analysis
Structural stability
Sulfur
thermodynamics
Unit cell
X-ray diffraction
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Summary:For the design of light‐metal–sulfur batteries and for the understanding of their performance, knowledge on the stable crystalline polysulfides is very important. We confronted experimental and ab initio crystal structure prediction studies on the stability of Na polysulfides. The selected evolutionary‐based structure‐prediction algorithm was able to quickly and correctly predict the thermodynamically stable crystalline forms of Na polysulfides with small unit cells. For Na polysulfides with large unit cells, the algorithm correctly proposed short unbranched polysulfide chains to be energetically favorite structural motifs, but could not find proper three‐dimensional structures in the limited number of generations. Experimentally, the polysulfides were studied by X‐ray diffraction and 23Na solid‐state NMR spectroscopy. Complemented by calculations of the isotropic chemical shifts and quadrupolar coupling constants, NMR spectroscopy proved to be an excellent tool for the examination of Na polysulfides, because it allowed easy distinction and quantification of components in the samples. Solids in Na–S batteries? Two tools for studying Na–S batteries are explored: ab initio crystal structure prediction for finding the potentially stable crystalline forms of sodium polysulfides and 23Na NMR spectroscopy for inspecting the composition of the batteries.
ISSN:0947-6539
1521-3765
DOI:10.1002/chem.201504242