A Novel Molten Oxide Fuel Cell Concept

Белоусов, В. В.; Fedorov, S. V.

doi:10.1002/fuce.201600031

Cited by 19 publications

(37 citation statements)

References 15 publications

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“…The structure and transport properties of the (supercooled) liquid phase also control crystal growth and are required for its optimization . Moreover, molten oxides are important materials in their own right as high-temperature hermetic seals and oxide ion conducting electrolytes for fuel cells and gas separation membranes, including those based on molten TeO 2 . , Although the structure of molten TeO 2 is less well studied than that of the glass, a recent Raman spectroscopic investigation has been interpreted in terms of a declining TeO coordination number with increasing temperature, along with a concomitant increase in the number of TeO doubly bonded terminal oxygen groups. Ab-initio molecular dynamics (MD) simulations support this interpretation to some extent, although the liquid states studied were highly pressurized due to the use of a fixed density, something that likely suppresses the coordination decrease.…”

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confidence: 99%

Short-Range Disorder in TeO₂ Melt and Glass

Alderman

Benmore

Feller

et al. 2019

J. Phys. Chem. Lett.

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High-resolution X-ray pair distribution functions for molten and glassy TeO2 reveal coordination numbers n TeO ≈ 4. However, distinct from the known α-, β-, and γ-TeO2 polymorphs, there is considerable short-range disorder such that no clear cutoff distance between bonded and nonbonded interactions exists. We suggest that this is similar to disorder in δ-TeO2 and arises from a broad distribution of asymmetric Te–O–Te bridges, something that we observe becomes increasingly asymmetric with increasing liquid temperature. Such behavior is qualitatively consistent with existing interpretations of Raman scattering spectra, and equivalent to temperature-induced coordination number reduction, for sufficiently large cutoff radii. Therefore, TeO2 contains a distribution of local environments that are, furthermore, temperature dependent, making it distinct from the canonical single-oxide glass formers. Our results are in good agreement with high-level ab initio cluster calculations.

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confidence: 99%

Short-Range Disorder in TeO₂ Melt and Glass

Alderman

Benmore

Feller

et al. 2019

J. Phys. Chem. Lett.

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“…To investigate how exactly Li-ions and oxide-ions migrate in Li 2 W 2 O 7 , the bond-valence-based method was applied in this work. This method has been well documented in the literature about how it is used for analyzing ion transport pathways statistically from crystal structure data , and has been extensively employed for the investigation of conduction pathways in various oxide-, ,− sodium-, and lithium-ion conductors. ,− For calculations using the bond-valence method, the ion to be tested was placed sequentially at all points of a three-dimensional grid covering a unit cell. Positions with a low bond-valence mismatch (( V i – ∑ S ij ), where V i corresponds to the formal oxidation state of ion i and S ij is the bond valence for the pair of ions i and j ), which is correlated to a low energy site and connecting equilibrium sites, form an infinite network for a potential migrating pathway …”

Section: Resultsmentioning

confidence: 99%

“…In addition to solid crystalline materials, molten binary oxides, such as Bi 2 O 3 , V 2 O 5 , and TeO 2 , have also been found with high oxide-ion conductivity. Very recently, we have reported a ternary oxide Na 2 W 2 O 7 with a high oxide-ion conductivity above its melting point .…”

Section: Introductionmentioning

confidence: 99%

“…6−8 Those with oxygen interstitials have been found in apatite-structured materials, 9−13 melilitestructured materials, 14−18 and, more recently, reported Ba 7 Nb 4 MoO 20 -based hexagonal perovskite-related oxides. 19 In addition to solid crystalline materials, molten binary oxides, such as Bi 2 O 3 , 20 V 2 O 5 , 21 and TeO 2 , 22 have also been found with high oxide-ion conductivity. Very recently, we have reported a ternary oxide Na 2 W 2 O 7 with a high oxide-ion conductivity above its melting point.…”

Section: ■ Introductionmentioning

confidence: 99%

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Electrical Properties, Defect Structures, and Ionic Conducting Mechanisms in Alkali Tungstate Li₂W₂O₇

et al. 2021

Inorg. Chem.

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Discovery of new high-conductivity solid-state ionic conductors has been a longlasting interest in the field of solid-state ionics for their important applications in solid-state electrochemical devices. Here, we report the mixed oxide-ion and Li-ion conductions, together with their conducting mechanisms in the Li 2 W 2 O 7 material with triclinic symmetry. The process for the ionic identity is supported by several electrochemical measurements including electrochemical impedance spectroscopy, DC polarization, oxygen concentration cell, and theoretical analysis of neutron diffraction data and bond-valence-based energy landscape calculations. We show from electrochemical measurements strong evidences of the predominating oxide-ion conducting and minor Li-ion chemistry in Li 2 W 2 O 7 at high temperatures, while the bond-valence-based energy landscape analysis reveals possible multidimensional ionic migration pathways for both oxide-ions and Li-ions. Thus, the presented results provide fundamental insights into new mixed ionic conduction mechanisms in low-symmetry materials and have implications for discoveries of new ionic conductors in years to come.

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“…[16][17][18][19][20] These membrane materials showed high oxygen selectivity and permeability. The ease of the MOM materials fabrication, combined with competitive oxygen permeability and superior oxygen selectivity, demonstrates a promising application.…”

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Oxygen Ion Transport in Molten Oxide Membranes for Air Separation and Energy Conversion

Климашин

Белоусов

2017

J. Electrochem. Soc.

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Molten oxide membranes (MOMs) are a new class of ion transport inorganic membranes which demonstrate superior oxygen selectivity and permeability and could be used in electrochemical devices such as molten oxide fuel cells (MOFCs) and oxygen separators for energy conversion and air separation, respectively [Acc. Chem. Res., 50, 273 (2017)]. However, oxygen ion transport mechanisms in MOM materials are not clear enough. Understanding the oxygen ion transport mechanisms in molten oxides is important for the discovery of new MOM materials with enhanced performances that can enable the operation of the electrochemical devices more efficiently. Here we suggest an approach that adapts a dynamic polymer chain model, developed for specific molten oxides, to a wide range of melts. This generic model can evaluate the oxygen permeation fluxes through different MOM materials that are comparable to experimental data. The study of ion transport membrane (ITM) materials and processes is a rapidly expanding research interest field. This is due to the fact that the ITM-based technology modules have the potential to improve the efficiency and environmental performances of energy generation systems.1,2 ITM can separate high purity oxygen from air at elevated temperatures and have the potential to reduce the cost of oxygen production in comparison with the conventional cryogenic process.3 The mixed-conducting perovskite-type compounds, 4,5 ceramic composites, 6-9 and cermets 10-13 are used as ITM materials. The practicalities for incorporating ceramic membrane materials into industrial processes are discussed in comprehensive reviews. 1,2Recently, the molten oxide membrane (MOM) materials have been developed. 14,15 This MOM materials consist of solid grains and intergranular liquid channels. The intergranular liquid channels provide the membrane material high ionic conductivity, gas tightness, and ductility. This last property allows us to deal successfully with the problem of thermal incompatibility (difference in coefficient of thermal expansion, CTE).There 14,15 Transport properties (electrical conductivity, oxygen ion transport number, and oxygen and nitrogen permeation fluxes) of these MOM materials have been measured. [16][17][18][19][20] These membrane materials showed high oxygen selectivity and permeability. The ease of the MOM materials fabrication, combined with competitive oxygen permeability and superior oxygen selectivity, demonstrates a promising application.Understanding the oxygen ion transport mechanisms in molten oxides is important for the discovery of new MOM materials that can enable the oxygen separation and energy conversion more efficiently. Recently, a dynamic polymer chain model for oxygen ion transport in molten V 2 O 5 has been developed. [21][22][23] In this paper, we suggest an approach that adapts the dynamic polymer chain model to a wide range of melts. This generic model can predict the gas permeation fluxes through molten oxide 14,15 and carbonate [24][25][26][27][28][29] membrane materials that a...

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A Novel Molten Oxide Fuel Cell Concept

Cited by 19 publications

References 15 publications

Short-Range Disorder in TeO₂ Melt and Glass

Short-Range Disorder in TeO₂ Melt and Glass

Electrical Properties, Defect Structures, and Ionic Conducting Mechanisms in Alkali Tungstate Li₂W₂O₇

Oxygen Ion Transport in Molten Oxide Membranes for Air Separation and Energy Conversion

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A Novel Molten Oxide Fuel Cell Concept

Cited by 19 publications

References 15 publications

Short-Range Disorder in TeO2 Melt and Glass

Short-Range Disorder in TeO2 Melt and Glass

Electrical Properties, Defect Structures, and Ionic Conducting Mechanisms in Alkali Tungstate Li2W2O7

Oxygen Ion Transport in Molten Oxide Membranes for Air Separation and Energy Conversion

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Product

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Short-Range Disorder in TeO₂ Melt and Glass

Short-Range Disorder in TeO₂ Melt and Glass

Electrical Properties, Defect Structures, and Ionic Conducting Mechanisms in Alkali Tungstate Li₂W₂O₇