Exploring the Influence of Substitution on the Structure and Transport Properties in the Sodium Superionic Conductor Na11+xSn2+x(Sb1−yPy)1−xS12

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 Na11+xSn2+x(Sb1-yPy)1-xS12. 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.

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Exploring the Influence of Substitution on the Structure and Transport Properties in the Sodium Superionic Conductor Na11+xSn2+x(Sb1−yPy)1−xS12

10.26434/chemrxiv.12278237.v2 ◽

2020 ◽

Author(s):

Marvin Kraft ◽

Lara Gronych ◽

Theodosios Famprikis ◽

Saneyuki Ohno ◽

Wolfgang Zeier

Keyword(s):

Electrochemical Impedance ◽

Structural Phase ◽

Ionic Transport ◽

Sodium Ion ◽

Ionic Conductors ◽

Temperature Dependent ◽

Activation Barriers ◽

Rietveld Refinements ◽

High Performing ◽

The Given

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 Na11+xSn2+x(Sb1-yPy)1-xS12. 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.

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A Lattice Dynamical Approach for Finding the Lithium Superionic Conductor Li3ErI6

10.26434/chemrxiv.11627451 ◽

2020 ◽

Author(s):

Roman Schlem ◽

Tim Bernges ◽

Cheng Li ◽

Marvin Kraft ◽

Nicolo Minafra ◽

...

Keyword(s):

Lattice Dynamics ◽

Ionic Conductivities ◽

Ionic Transport ◽

Superionic Conductors ◽

Material System ◽

Ionic Conductors ◽

Anion Sublattice ◽

Temperature Dependent ◽

Solid State Batteries ◽

Debye Frequency

Driven by the increasing attention that the superionic conductors Li3MX6 (M = Y, Er, In, La; X = Cl, Br, I) have gained recently for the use of solid-state batteries, and the idea that a softer, more polarizable anion sublattice is beneficial for ionic transport, here we report Li3ErI6, the first experimentally-obtained iodine-based compound within this material system of ionic conductors. Using a combination of synchrotron and neutron diffraction, we elucidate the structure, the lithium positions and possible diffusion pathways of Li3ErI6. Temperature-dependent impedance spectroscopy shows low activation energies of 0.37 and 0.38 eV alongside promising ionic conductivities of 0.65 mS·cm-1 and 0.39 mS·cm-1directly after ball milling and the subsequently annealed Li3ErI6, respectively. Speed of sound measurements are used to determine the Debye frequency of the lattice as a descriptor of the lattice dynamics and overall lattice softness, and Li3ErI6 is compared to the known material Li3ErCl6. The softer, more polarizable framework from the iodide anion leads to improved ionic transport, showing that the idea of softer lattices holds up in this class of materials. This work provides Li3ErI6 as an interesting novel framework for optimization in the class of halide-based ionic conductors.

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A Lattice Dynamical Approach for Finding the Lithium Superionic Conductor Li3ErI6

10.26434/chemrxiv.11627451.v1 ◽

2020 ◽

Author(s):

Roman Schlem ◽

Tim Bernges ◽

Cheng Li ◽

Marvin Kraft ◽

Nicolo Minafra ◽

...

Keyword(s):

Lattice Dynamics ◽

Ionic Conductivities ◽

Ionic Transport ◽

Superionic Conductors ◽

Material System ◽

Ionic Conductors ◽

Anion Sublattice ◽

Temperature Dependent ◽

Solid State Batteries ◽

Debye Frequency

Driven by the increasing attention that the superionic conductors Li3MX6 (M = Y, Er, In, La; X = Cl, Br, I) have gained recently for the use of solid-state batteries, and the idea that a softer, more polarizable anion sublattice is beneficial for ionic transport, here we report Li3ErI6, the first experimentally-obtained iodine-based compound within this material system of ionic conductors. Using a combination of synchrotron and neutron diffraction, we elucidate the structure, the lithium positions and possible diffusion pathways of Li3ErI6. Temperature-dependent impedance spectroscopy shows low activation energies of 0.37 and 0.38 eV alongside promising ionic conductivities of 0.65 mS·cm-1 and 0.39 mS·cm-1directly after ball milling and the subsequently annealed Li3ErI6, respectively. Speed of sound measurements are used to determine the Debye frequency of the lattice as a descriptor of the lattice dynamics and overall lattice softness, and Li3ErI6 is compared to the known material Li3ErCl6. The softer, more polarizable framework from the iodide anion leads to improved ionic transport, showing that the idea of softer lattices holds up in this class of materials. This work provides Li3ErI6 as an interesting novel framework for optimization in the class of halide-based ionic conductors.

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On the Properties of an Ion Conductive System Incorporated in Hybrid Films

MRS Proceedings ◽

10.1557/proc-628-cc6.19 ◽

2000 ◽

Vol 628 ◽

Author(s):

G. González ◽

P. J. Retuert ◽

S. Fuentes

Keyword(s):

Electrochemical Impedance ◽

Ternary Phase Diagram ◽

Lithium Perchlorate ◽

Molar Ratio ◽

Ionic Conductors ◽

X Ray Diffraction ◽

Poly Ethylene Oxide ◽

Ion Conducting ◽

Poly Ethylene ◽

High Degree

ABSTRACTBlending the biopolymer chitosan (CHI) with poly (aminopropilsiloxane) oligomers (pAPS), and poly (ethylene oxide) (PEO) in the presence of lithium perchlorate lead to ion conducting products whose conductivity depends on the composition of the mixture. A ternary phase diagram for mixtures containing 0.2 M LiClO4 shows a zone in which the physical properties of the products - transparent, flexible, mechanically robust films - indicate a high degree of molecular compatibilization of the components. Comparison of these films with binary CHI-pAPS nanocomposites as well as the microscopic aspect, thermal behavior, and X-ray diffraction pattern of the product with the composition PEO/CHI/pAPS/LiClO4 1:0.5:0.6:0.2 molar ratio indicates that these films may be described as a layered nanocomposite. In this composite, lithium species coordinated by PEO and pAPS should be inserted into chitosan layers. Electrochemical impedance spectroscopy measurements indicate the films are pure ionic conductors with a maximal bulk conductivity of 1.7*10-5 Scm-1 at 40 °C and a sample-electrode interface capacitance of about 1.2*10-9 F.

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How Certain Are the Reported Ionic Conductivities of Thiophosphate-Based Solid Electrolytes? an Interlaboratory Study

10.26434/chemrxiv.11316497.v2 ◽

2020 ◽

Author(s):

Saneyuki Ohno ◽

Tim Bernges ◽

Johannes Buchheim ◽

Marc Duchardt ◽

Anna-Katharina Hatz ◽

...

Keyword(s):

Standard Deviation ◽

Ionic Conductivity ◽

Relative Standard Deviation ◽

Solid Electrolytes ◽

Ionic Conductivities ◽

Ionic Conductors ◽

Energy Storage Devices ◽

Activation Barriers ◽

Storage Devices ◽

Relative Standard

Owing to highly conductive solid ionic conductors, all-solid-state batteries attract significant attention as promising next-generation energy storage devices. A lot of research is invested in the search and optimization of solid electrolytes with higher ionic conductivity. However, a systematic study of an interlaboratory reproducibility of measured ionic conductivities and activation energies is missing, making the comparison of absolute values in literature challenging. In this study, we perform an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials. Identical samples are distributed to different research laboratories and the conductivities and activation barriers are measured by impedance spectroscopy. The results show large ranges of up to 4.5 mScm-1 in the measured total ionic conductivity (1.3 – 5.8 mScm-1 for the highest conducting sample, relative standard deviation 35 – 50% across all samples) and up to 128 meV for the activation barriers (198 – 326 meV, relative standard deviation 5 – 15%, across all samples), presenting the necessity of a more rigorous methodology including further collaborations within the community and multiplicate measurements.

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Defect-Mediated Conductivity Enhancements in Na3-xPn1-xWxS4 (Pn = P, Sb) using Aliovalent Substitutions

10.26434/chemrxiv.9943961.v2 ◽

2019 ◽

Author(s):

Till Fuchs ◽

Sean Culver ◽

Paul Till ◽

Wolfgang Zeier

Keyword(s):

Ionic Conductivity ◽

Vacancy Concentration ◽

Sodium Ion ◽

High Ionic Conductivity ◽

Ionic Conductors ◽

X Ray Diffraction ◽

X Ray ◽

Solid State Batteries ◽

Ion Conducting ◽

Very High

The sodium-ion conducting family of Na3PnS4, with Pn = P, Sb, have gained interest for the use in solid-state batteries due to their high ionic conductivity. However, significant improvements to the conductivity have been hampered by the lack of aliovalent dopants that can introduce vacancies into the structure. Inspired by the need for vacancy introduction into Na3PnS4, the solid solutions with WS42- introduction are explored. The influence of the substitution with WS42- for PS43- and SbS43-, respectively, is monitored using a combination of X-ray diffraction, Raman and impedance spectroscopy. With increasing vacancy concentration improvements resulting in a very high ionic conductivity of 13 ± 3 mS·cm-1 for Na2.9P0.9W0.1S4 and 41 ± 8 mS·cm-1 for Na2.9Sb0.9W0.1S4 can be observed. This work acts as a stepping-stone towards further engineering of ionic conductors using vacancy-injection via aliovalent substituents.

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Defect-Mediated Conductivity Enhancements in Na3-xPn1-xWxS4 (Pn = P, Sb) using Aliovalent Substitutions

10.26434/chemrxiv.9943961.v1 ◽

2019 ◽

Author(s):

Till Fuchs ◽

Sean Culver ◽

Paul Till ◽

Wolfgang Zeier

Keyword(s):

Ionic Conductivity ◽

Vacancy Concentration ◽

Sodium Ion ◽

High Ionic Conductivity ◽

Ionic Conductors ◽

X Ray Diffraction ◽

X Ray ◽

Solid State Batteries ◽

Ion Conducting ◽

Very High

The sodium-ion conducting family of Na3PnS4, with Pn = P, Sb, have gained interest for the use in solid-state batteries due to their high ionic conductivity. However, significant improvements to the conductivity have been hampered by the lack of aliovalent dopants that can introduce vacancies into the structure. Inspired by the need for vacancy introduction into Na3PnS4, the solid solutions with WS42- introduction are explored. The influence of the substitution with WS42- for PS43- and SbS43-, respectively, is monitored using a combination of X-ray diffraction, Raman and impedance spectroscopy. With increasing vacancy concentration improvements resulting in a very high ionic conductivity of 13 ± 3 mS·cm-1 for Na2.9P0.9W0.1S4 and 41 ± 8 mS·cm-1 for Na2.9Sb0.9W0.1S4 can be observed. This work acts as a stepping-stone towards further engineering of ionic conductors using vacancy-injection via aliovalent substituents.

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Anion ordering enables fast H− conduction at low temperatures

Science Advances ◽

10.1126/sciadv.abf7883 ◽

2021 ◽

Vol 7 (23) ◽

pp. eabf7883

Author(s):

Hiroki Ubukata ◽

Fumitaka Takeiri ◽

Kazuki Shitara ◽

Cédric Tassel ◽

Takashi Saito ◽

...

Keyword(s):

Ionic Conductivity ◽

Room Temperature ◽

Structural Transition ◽

Hexagonal Lattice ◽

Ionic Conductors ◽

Activation Barriers ◽

Energy Devices ◽

Energy Applications ◽

Chemical Disorder ◽

New Energy

The introduction of chemical disorder by substitutional chemistry into ionic conductors is the most commonly used strategy to stabilize high-symmetric phases while maintaining ionic conductivity at lower temperatures. In recent years, hydride materials have received much attention owing to their potential for new energy applications, but there remains room for development in ionic conductivity below 300°C. Here, we show that layered anion-ordered Ba2−δH3−2δX (X = Cl, Br, and I) exhibit a remarkable conductivity, reaching 1 mS cm−1 at 200°C, with low activation barriers allowing H− conduction even at room temperature. In contrast to structurally related BaH2 (i.e., Ba2H4), the layered anion order in Ba2−δH3−2δX, along with Schottky defects, likely suppresses a structural transition, rather than the traditional chemical disorder, while retaining a highly symmetric hexagonal lattice. This discovery could open a new direction in electrochemical use of hydrogen in synthetic processes and energy devices.

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Temperature-induced structural phase transitions in RERhSn (RE = Y, Gd-Tm, Lu)

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1515/zkri-2021-2008 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Simon Engelbert ◽

Rolf-Dieter Hoffmann ◽

Jutta Kösters ◽

Steffen Klenner ◽

Rainer Pöttgen

Keyword(s):

Rare Earth ◽

Phase Transitions ◽

Driving Force ◽

Room Temperature ◽

Structural Phase ◽

Structural Phase Transitions ◽

Line Broadening ◽

X Ray Diffraction ◽

Temperature Dependent ◽

X Ray

Abstract The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

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