Sulfidic sodium ion conductors are currently investigated for the possible use in all-solid-state sodium ion batteries. The design of high-performing electrolytes in terms of temperature-dependent ionic transport is based upon the fundamental understanding of structure–transport relationships within the given structural phase boundaries inherent to the investigated materials class. In this work, the Na+ superionic structural family of Na11Sn2PS12 is explored by using the systematic antimony substitution with phosphorus in Na11+x Sn2+x (Sb1–y P y )1–x S12. A combination of Rietveld refinements against X-ray synchrotron diffraction data with electrochemical impedance spectroscopy is used to monitor the changes in the anionic framework, the Na+ substructure, and the ionic transport. A new simplified descriptor for the average Na+ diffusion pathways, the average Na+ polyhedral volume, is introduced, which is used to correlate the contraction of the overall lattice and the found activation barriers in the system. This study exemplifies how substitution affects diffusion pathways in ionic conductors and widens the knowledge about the related structural motifs and their influence on the ionic transport in this novel class of ionic conductors.

Exploration of sulfidic sodium solid electrolytes and their design contributes to advances in solid state sodium batteries. Such design is guided by a better understanding of fast sodium transport, for instance in the herein studied Na 11 Sn 2 PS 12 -type materials. By using Rietveld refinements against synchrotron X-ray diffraction and electrochemical impedance spectroscopy, the influence of aliovalent substitution onto the structure and transport in Na 11+x Sn 2 P 1−x M x S 12 with M = Ge and Sn is investigated. Whereas Sn induces stronger structural changes than Ge, the found influence on the sodium sublattice and the ionic transport properties are comparable. Overall, a reduced in-grain activation energy of Na + transport can be found with the reducing Na + vacancy concentration. This work explores previously unreported phases in the Na 11 Sn 2 PS 12 structure type that, based on their determined properties reveal Na + vacancy concentrations to be an important factor guiding further understanding within Na 11 Sn 2 PS 12 -type materials. File list (2) download file view on ChemRxiv manuscript.pdf (1.80 MiB) download file view on ChemRxiv Supporting Information.pdf (2.83 MiB)

Understanding the correlation between ionic motion and crystal structure is crucial for improving solid electrolyte conductivities. Several substitutions in the Li10GeP2S12 structure have been shown favorable impact on the ionic...

<p>Exploration of sulfidic sodium solid electrolytes and their design contributes to advances in solid state sodium batteries. Such design is guided by a better understanding of fast sodium transport, for instance in the herein studied Na₁₁Sn₂PS₁₂-type materials. By using Rietveld refinements against synchrotron X-ray diffraction and electrochemical impedance spectroscopy, the influence of aliovalent substitution onto the structure and transport in Na_11+<i>x</i>Sn₂P_1−<i>x</i><i>M_x</i>S₁₂ with <i>M</i> = Ge and Sn is investigated. Whereas Sn induces stronger structural changes than Ge, the found influence on the sodium sublattice and the ionic transport properties are comparable. Overall, a reduced in-grain activation energy of Na⁺ transport can be found with the reducing Na⁺ vacancy concentration. This work explores previously unreported phases in the Na₁₁Sn₂PS₁₂ structure type that, based on their determined properties reveal Na⁺ vacancy concentrations to be an important factor guiding further understanding within Na₁₁Sn₂PS₁₂-type materials.</p>

<p>Sulfidic sodium ion conductors are currently investigated for the possible use in all-solid-state sodium ion batteries. The design of high performing electrolytes in terms of temperature-dependent ionic transport is based upon the fundamental understanding of structure – transport relationships within the given structural phase boundaries inherent to the investigated materials class. In this work, the Na⁺ superionic structural family of Na₁₁Sn₂PS₁₂ is explored by using the systematic antimony substitution with phosphorous in Na_11+<i>x</i>Sn_2+<i>x</i>(Sb_1-<i>y</i>P<i>_y</i>)_1-<i>x</i>S₁₂. A combination of Rietveld refinements against X-ray synchrotron diffraction data with electrochemical impedance spectroscopy is used to monitor the changes in the anionic framework, the Na⁺ substructure and the ionic transport. A new simplified descriptor for the average Na⁺ diffusion pathways, the average Na⁺ polyhedral volume is introduced, which is used to correlate the contraction of the overall lattice and the found activation barriers in the system. This study exemplifies how substitution affects diffusion pathways in ionic conductors and widens the knowledge about the related structural motifs and their influence on the ionic transport in this novel class of ionic conductors.</p>