New Good Ionic Conductor: Ba-Deficient Ba3Y4O9 with Zr Substitution

10.26434/chemrxiv.13385228 ◽

2020 ◽

Author(s):

Katsuhiro Ueno ◽

Naoyuki Hatada ◽

Tetsuya Uda

Keyword(s):

Solid Oxide Fuel Cells ◽

Ionic Conduction ◽

Ionic Conductor ◽

Electronic Conduction ◽

Ionic Conductors ◽

Conducting Phase ◽

Conducting Oxides ◽

Total Electrical Conductivity ◽

Ion Conducting ◽

New Good

To lower operating temperatures of solid oxide fuel cells (SOFCs), the development of ion-conducting oxides with high conductivity and durability is desired. In this work, we investigated Zr-substituted “Ba3Y4O9” as an ionic conductor at intermediate temperatures and found that the Zr substitution for Y dramatically improves the phase stability in humidified atmospheres at 300-800 °C. The total electrical conductivity of 20 mol% Zr-substituted Ba3Y4O9 is about 1 mS/cm at 700 °C in dry H2 and O2 atmospheres and the contribution of electronic conduction (both hole and electron) is relatively small compared with Y-doped BaZrO3 (BZY) and Gd-doped CeO2 (GDC) which are typical intermediate-temperature ionic conductors. Besides, in the Zr-substituted “Ba3Y4O9” samples, we observed that BaO-rich amorphous phase coexists with the main phase whose composition is estimated to be Ba:(Y+Zr) ~ 2:3. Therefore, the main conducting phase might be Ba-deficient Ba3Y4O9. The mechanism of the ionic conduction and the improvement of chemical stability has not been revealed yet due to the lack of crystallographic information about the Ba-deficient phase. While we are now working on further investigation, we promptly report the characteristic of the new compound.

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Direct-Hydrocarbon Proton-Conducting Solid Oxide Fuel Cells

Sustainability ◽

10.3390/su13094736 ◽

2021 ◽

Vol 13 (9) ◽

pp. 4736

Author(s):

Fan Liu ◽

Chuancheng Duan

Keyword(s):

Fuel Cells ◽

Solid Oxide Fuel Cells ◽

Solid Oxide ◽

Sulfur Poisoning ◽

Oxide Fuel ◽

Power Sources ◽

Proton Conducting ◽

Conducting Oxides ◽

Operating Temperatures ◽

Ion Conducting

Solid oxide fuel cells (SOFCs) are promising and rugged solid-state power sources that can directly and electrochemically convert the chemical energy into electric power. Direct-hydrocarbon SOFCs eliminate the external reformers; thus, the system is significantly simplified and the capital cost is reduced. SOFCs comprise the cathode, electrolyte, and anode, of which the anode is of paramount importance as its catalytic activity and chemical stability are key to direct-hydrocarbon SOFCs. The conventional SOFC anode is composed of a Ni-based metallic phase that conducts electrons, and an oxygen-ion conducting oxide, such as yttria-stabilized zirconia (YSZ), which exhibits an ionic conductivity of 10−3–10−2 S cm−1 at 700 °C. Although YSZ-based SOFCs are being commercialized, YSZ-Ni anodes are still suffering from carbon deposition (coking) and sulfur poisoning, ensuing performance degradation. Furthermore, the high operating temperatures (>700 °C) also pose challenges to the system compatibility, leading to poor long-term durability. To reduce operating temperatures of SOFCs, intermediate-temperature proton-conducting SOFCs (P-SOFCs) are being developed as alternatives, which give rise to superior power densities, coking and sulfur tolerance, and durability. Due to these advances, there are growing efforts to implement proton-conducting oxides to improve durability of direct-hydrocarbon SOFCs. However, so far, there is no review article that focuses on direct-hydrocarbon P-SOFCs. This concise review aims to first introduce the fundamentals of direct-hydrocarbon P-SOFCs and unique surface properties of proton-conducting oxides, then summarize the most up-to-date achievements as well as current challenges of P-SOFCs. Finally, strategies to overcome those challenges are suggested to advance the development of direct-hydrocarbon SOFCs.

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Synthesis of Functional Ceramic Materials for Application in 2 kW Stationary SOFC Stacks

Materials Science Forum ◽

10.4028/www.scientific.net/msf.730-732.147 ◽

2012 ◽

Vol 730-732 ◽

pp. 147-152

Author(s):

Antonio E. Martinelli ◽

Daniel A. Macedo ◽

Moisés R. Cesário ◽

Beatriz Cela ◽

Juliana P. Nicodemo ◽

...

Keyword(s):

Solid Oxide Fuel Cells ◽

Ceramic Materials ◽

Composite Cathode ◽

Ionic Conductors ◽

Oxygen Ion ◽

One Step ◽

Ion Conducting ◽

Power Densities ◽

Sofc Stacks ◽

Functional Ceramic

This paper presents an overview of recent advances in the synthesis and preparation of solid oxide fuel cells (SOFCs) functional ceramic materials, focusing on low-/intermediary-temperature SOFCs. Novel synthesis processes for oxygen ion-conducting and mixed electronic and ionic conductors, fundamental to reduce the operating temperature of SOFCs were studied. Ni-Ce0.9Gd0.1O1.95 (Ni-CGO) anodes were successfully synthesized by the so called “one step synthesis”. La0.5Sr0.5Co0.8Fe0.2O3 (LSCF), Ce0.8Sm0.2O1.9 (SDC) and their mixture were produced as a cobaltite-based composite cathode by mixing powders synthesized by microwave-assisted combustion and the modified polymeric precursor method, respectively. Preliminary electrochemical activity tests with the synthesized electrodes were performed in electrolyte-supported SOFCs using commercially available 200 µm thick yttria stabilized zirconia (8YSZ) as electrolyte. The maximum power density of 52 mW/cm2 was reached at 850 °C. This result can be further improved replacing thick YSZ electrolytes by doped-ceria thin films, aiming at operation temperatures of 500–800 °C and power densities as high as 800 mW/cm2. The assembling of anode-supported cells with the configuration Ni-CGO/CGO (10 µm thickness)/LSCF-SDC are for applications in 2 kW stacks are currently under way.

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Ionic Conductors: Effect of Temperature on Conductivity and Mechanical Properties and Their Interrelations

Crystals ◽

10.3390/cryst11081008 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1008

Author(s):

Masaru Aniya ◽

Haruhito Sadakuni ◽

Eita Hirano

Keyword(s):

Mechanical Properties ◽

Ionic Conduction ◽

Effect Of Temperature ◽

Large Temperature ◽

Grüneisen Parameter ◽

Ionic Conductors ◽

Gruneisen Parameter ◽

Crystalline Materials ◽

Intimate Relation ◽

Ion Conducting

The ionic transport and the mechanical properties in solids are intimately related. However, few studies have been done to elucidate the background of that relation. With the objective to fill this gap and gain further understanding on the fundamental properties of ion conducting materials, we are studying systematically the mechanical properties of different materials. In the present study, after showing briefly our previous results obtained in crystalline materials, results regarding the relation between ionic conduction and mechanical properties in superionic glasses is presented. All these results indicate the intimate relation between the mechanical and ionic conduction. The results also indicate that the Grüneisen parameter and the Anderson–Grüneisen parameter of ionic conductors exhibit large temperature dependence and increase with temperature.

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Recent Progress in Semiconductor-Ionic Conductor Nanomaterial as a Membrane for Low-Temperature Solid Oxide Fuel Cells

Nanomaterials ◽

10.3390/nano11092290 ◽

2021 ◽

Vol 11 (9) ◽

pp. 2290

Author(s):

Yuzheng Lu ◽

Youquan Mi ◽

Junjiao Li ◽

Fenghua Qi ◽

Senlin Yan ◽

...

Keyword(s):

Fuel Cells ◽

Low Temperature ◽

Solid Oxide Fuel Cells ◽

Recent Progress ◽

Operating Temperature ◽

Critical Role ◽

Ionic Conductor ◽

Solid Oxide ◽

Oxide Fuel ◽

Ionic Conductors

Reducing the operating temperature of Solid Oxide Fuel Cells (SOFCs) to 300–600 °C is a great challenge for the development of SOFC. Among the extensive research and development (R&D) efforts that have been done on lowering the operating temperature of SOFCs, nanomaterials have played a critical role in improving ion transportation in electrolytes and facilitating electrochemical catalyzation of the electrodes. This work reviews recent progress in lowering the temperature of SOFCs by using semiconductor-ionic conductor nanomaterial, which is typically a composition of semiconductor and ionic conductor, as a membrane. The historical development, as well as the working mechanism of semiconductor-ionic membrane fuel cell (SIMFC), is discussed. Besides, the development in the application of nanostructured pure ionic conductors, semiconductors, and nanocomposites of semiconductors and ionic conductors as the membrane is highlighted. The method of using nano-structured semiconductor-ionic conductors as a membrane has been proved to successfully exhibit a significant enhancement in the ionic conductivity and power density of SOFCs at low temperatures and provides a new way to develop low-temperature SOFCs.

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A transmission electron microscopic study of structural transitions in fast ionic conductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100125713 ◽

1987 ◽

Vol 45 ◽

pp. 156-157

Author(s):

R. B. Queenan ◽

P. K. Davies

Keyword(s):

Optical Properties ◽

Ionic Conduction ◽

Recent Observation ◽

Ionic Conductivities ◽

Sodium Aluminate ◽

Two Dimensions ◽

Ionic Conductors ◽

Electron Microscopic ◽

Transmission Electron ◽

Trivalent Cations

Na ß“-alumina (Na1.67Mg67Al10.33O17) is a non-stoichiometric sodium aluminate which exhibits fast ionic conduction of the Na+ ions in two dimensions. The Na+ ions can be exchanged with a variety of mono-, di-, and trivalent cations. The resulting exchanged materials also show high ionic conductivities.Considerable interest in the Na+-Nd3+-ß“-aluminas has been generated as a result of the recent observation of lasing in the pulsed and cw modes. A recent TEM investigation on a 100% exchanged Nd ß“-alumina sample found evidence for the intergrowth of two different structure types. Microdiffraction revealed an ordered phase coexisting with an apparently disordered phase, in which the cations are completely randomized in two dimensions. If an order-disorder transition is present then the cooling rates would be expected to affect the microstructures of these materials which may in turn affect the optical properties. The purpose of this work was to investigate the affect of thermal treatments upon the micro-structural and optical properties of these materials.

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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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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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Sodium, Silver and Lithium-Ion Conducting β″-Alumina + YSZ Composites, Ionic Conductivity and Stability

Crystals ◽

10.3390/cryst11030293 ◽

2021 ◽

Vol 11 (3) ◽

pp. 293

Author(s):

Liangzhu Zhu ◽

Anil V. Virkar

Keyword(s):

Ion Exchange ◽

Electrochemical Impedance ◽

Ionic Conductivities ◽

Lithium Ion ◽

Co2 Corrosion ◽

Ionic Conductors ◽

Ion Conductor ◽

Sensor Applications ◽

Potential Applications ◽

Ion Conducting

Na-β″-alumina (Na2O.~6Al2O3) is known to be an excellent sodium ion conductor in battery and sensor applications. In this study we report fabrication of Na- β″-alumina + YSZ dual phase composite to mitigate moisture and CO2 corrosion that otherwise can lead to degradation in pure Na-β″-alumina conductor. Subsequently, we heat-treated the samples in molten AgNO3 and LiNO3 to respectively form Ag-β″-alumina + YSZ and Li-β″-alumina + YSZ to investigate their potential applications in silver- and lithium-ion solid state batteries. Ion exchange fronts were captured via SEM and EDS techniques. Their ionic conductivities were measured using electrochemical impedance spectroscopy. Both ion exchange rates and ionic conductivities of these composite ionic conductors were firstly reported here and measured as a function of ion exchange time and temperature.

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