One-step fabrication of protonic ceramic fuel cells using a convenient tape calendering method

The present paper reports the preparation of multilayer protonic ceramic fuel cells (PCFCs) using a single sintering step. The success of this fabrication approach is due to two main factors: the rational choice of chemically and mechanically compatible components, as well as the selection of a convenient preparation (tape calendering) method. The PCFCs prepared in this manner consisted of a 30 μm BaCe0.5Zr0.3Dy0.2O3-δ (BCZD) electrolyte layer, a 500 μm Ni-BCZD supporting electrode layer and a 20 μm functional Pr1.9Ba0.1NiO4+δ (PBN)-BCZD cathode layer. These layers were jointly co-fired at 1350 °C for 5 h to reach excellent gas-tightness of the electrolyte and porous structures for the supported and functional electrodes. The adequate fuel cell performance of this PCFC design (400 mW cm-2 at 600 °C) demonstrates that the tape calendering method compares well with such conventional laboratory PCFC preparation techniques such as co-pressing and tape-casting. © 2020 by the authors.Russian Foundation for Basic Research, RFBR: 18-38-20063This work was supported by the Russian Foundation for Basic Research, grant number 18-38-20063. The authors thank G. Vdovin for his assistance in experiments. The SEM characterisation was carried out at the Shared Access Centre "Composition of Compounds" of the Institute of High-Temperature Electrochemistry [51]

Towards high-performance tubular-type protonic ceramic electrolysis cells with all-Ni-based functional electrodes

Protonic ceramic electrolysis cells (PCECs), which permit high-temperature electrolysis of water, exhibit various advantages over conventional solid oxide electrolysis cells (SOECs), including cost-effectiveness and the potential to operate at low-/intermediate-temperature ranges with high performance and efficiency. Although many efforts have been made in recent years to improve the electrochemical characteristics of PCECs, certain challenges involved in scaling them up remain unresolved. In the present work, we present a twin approach of combining the tape-calendering method with all-Ni-based functional electrodes with the aim of fabricating a tubular-designed PCEC having an enlarged electrode area (4.6 cm2). This cell, based on a 25 µm-thick BaCe0.5Zr0.3Dy0.2O3–δ proton-conducting electrolyte, a nickel-based cermet and a Pr1.95Ba0.05NiO4+δ oxygen electrode, demonstrates a high hydrogen production rate (19 mL min–1 at 600 °C), which surpasses the majority of results reported for traditional button- or planar-type PCECs. These findings increase the scope for scaling up solid oxide electrochemical cells and maintaining their operability at reducing temperatures. © 2019 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of SciencesRussian Foundation for Basic Research, RFBR: 18-38-20063Council on grants of the President of the Russian FederationThis work was supported by the Russian Foundation for Basic Research (grant no. 18-38-20063 ). Dr. D. Medvedev is grateful to the Council of the President of the Russian Federation (scholarship no. СП−161.2018.1) for supporting the studies devoted to new MIEC materials. Other sections are performed within the framework of the budgetary plans of the Institute of High Temperature Electrochemistry

A reversible protonic ceramic cell with symmetrically designed Pr2NiO4+δ-based electrodes: Fabrication and electrochemical features

Reversible protonic ceramic cells (rPCCs) combine two different operation regimes, fuel cell and electrolysis cell modes, which allow reversible chemical-to-electrical energy conversion at reduced temperatures with high efficiency and performance. Here we present novel technological and materials science approaches, enabling a rPCC with symmetrical functional electrodes to be prepared using a single sintering step. The response of the cell fabricated on the basis of P-N- BCZD|BCZD|PBN-BCZD (where BCZD = BaCe0.5Zr0.3Dy0.2O3-δ, PBN = Pr1.9Ba0.1NiO4+δ, P = Pr2O3, N = Ni) is studied at different temperatures and water vapor partial pressures (pH2O) by means of volt-ampere measurements, electrochemical impedance spectroscopy and distribution of relaxation times analyses. The obtained results demonstrate that symmetrical electrodes exhibit classical mixed-ionic/electronic conducting behavior with no hydration capability at 750 °C; therefore, increasing the pH2O values in both reducing and oxidizing atmospheres leads to some deterioration of their electrochemical activity. At the same time, the electrolytic properties of the BCZD membrane are improved, positively affecting the rPCC's efficiency. The electrolysis cell mode of the rPCC is found to be more appropriate than the fuel cell mode under highly humidified atmospheres, since its improved performance is determined by the ohmic resistance, which decreases with pH2O increasing. © 2018 by the authors.Российский Фонд Фундаментальных Исследований (РФФИ): 18-38-20063Funding: The majority of this work was carried out under the budgetary plans of Institute of High Temperature Electrochemistry. The design of new electrode materials and their characterization was also funded by the Russian Foundation for Basic Research, grant number 18-38-20063. Dr. Dmitry Medvedev is also grateful to the Council of the President of the Russian Federation (scholarship СП-161.2018.1) for supporting the studies devoted to search of new Co-free electrode materials

Nickel-Containing Perovskites, PrNi0.4Fe0.6O3–δ and PrNi0.4Co0.6O3–δ, as Potential Electrodes for Protonic Ceramic Electrochemical Cells

Protonic ceramic fuel cells (PCFCs) offer a convenient means of converting chemical energy into electricity with high performance and efficiency at low-and intermediate-temperature ranges. However, in order to ensure good life-time stability of PCFCs, it is necessary to ensure rational chemical design in functional materials. Within the present work, we propose new Ni-based perovskite phases of PrNi0.4M0.6O3–δ (where M = Co, Fe) for potential utilization in protonic ceramic electrochemical cells. Along with their successful synthesis, functional properties of the PrNi0.4M0.6O3–δ materials, such as chemical compatibility with a number of oxygen-ionic and proton-conducting electrolytes, thermal expansion behavior, electrical conductivity, and electrochemical behavior, were comprehensively studied. According to the obtained data, the Co-containing nickelate exhibits excellent conductivity and polarization behavior; on the other hand, it demonstrates a high reactivity with all studied electrolytes along with elevated thermal expansion coefficients. Conversely, while the iron-based nickelate had superior chemical and thermal compatibility, its transport characteristics were 2–5 times worse. Although, PrNi0.4Co0.6O3–δ and PrNi0.4Fe0.6O3–δ represent some disadvantages, this work provides a promising pathway for further improvement of Ni-based perovskite electrodes. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.The characterization of powder and ceramic materials was carried out at the Shared Access Centre “Composition of Compounds” of Institute of High-Temperature Electrochem-istry (Ekaterinburg, Russia). We would like to give a special thanks to Natalia Popova and Thomas Beavitt for the performed proofreading [73]

Densification, morphological and transport properties of functional La1–xBaxYbO3– δ ceramic materials

The effective operation of protonic ceramic electrochemical cells requires the design of electrolytes having not only high ionic conductivity, but also excellent stability with respect to carbonisation. In the present work, the La-based oxides (La1–xBaxYbO3–δ, 0.03 ≤ x ≤ 0.10) are proposed as a possible alternative to the convenient Ba(Ce,Zr)O3-based electrolytes due to their high chemical stability. It was discovered that Ba-doping results in a deterioration of sintering behaviour; as a result, the relative density decreases and open porosity appears (for x = 0.10). A thorough analysis of transport properties by means of AC and DC measurement techniques enables a selection of the La0.97Ba0.03YbO3–δ sample, which demonstrates the highest conductivity compared with those samples where x = 0.5 and 0.10. Due to its excellent densification behaviour, stability and ionic conductivity, La0.97Ba0.03YbO3–δ can be considered as a promising proton-conducting electrolyte in the La-based family. © 2019 Elsevier Lt

Correction: CO 2 -promoted hydrogen production in a protonic ceramic electrolysis cell (Journal of Materials Chemistry A (2018) 6 (16341-16346) DOI: 10.1039/C8TA05820B)

The authors regret an error in the Fig. 2(d) caption. The text "U=1.3 V" in the published version should instead read "U=1.6 V". The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers. © 2018 The Royal Society of Chemistry

Sulfur and carbon tolerance of BaCeO3-BaZrO3 proton-conducting materials

In the present work, BaCe0.8-xZrxY0.2O3-delta-based ceramic samples (BCZYx) are prepared and their chemical stability in corrosive atmospheres containing high concentrations of H2O, CO2 and H2S is investigated. Based on both the fresh (not exposed) and the treated (exposed to corrosive atmospheres) samples, the estimation of the tolerance degree is obtained by determining the: i) phase structures, ii) unit cell parameters, iii) surface microstructures, and iv) electrical conductivities. Fresh ceramics is found to be single-phased in the whole range of x. It is also found that all the treated materials exhibit good chemical stability in the water vapor atmosphere, whereas the samples with 0 <= x <= 0.2 and 0 <= x <= 0.3 are not single-phased in pure CO2 and 10% H2S/Ar, respectively. The analysis of crystal structure and transport characteristics of the treated BCZY0.3 samples is shown a weak deviation of unit cell parameters and no degradation in electrical conductivity. For fresh BCZY0.3 the transport nature in various atmospheres is evaluated. At 600 degrees C the BCZY0.3 exhibits conductivity of 2.7, 4.0, 1.7 and 3.7 mS cm(-1) in air, wet air, hydrogen and wet hydrogen atmospheres, respectively. Based on the obtained results, BCZY0.3 can be considered as a perspective proton-conducting material having reasonable transport and tolerance properties. (C) 2014 Elsevier B.V. All rights reserved

Textured BaCe(0.5)Zr(0.3)Ln(0.2)O(3-delta) (Ln = Yb, Y, Gd, Sm, Nd and La) ceramics obtained by the aid of solid-state reactive sintering method

Dense BaCe(0.5)Zr(0.3)Ln(0.2)O(3-delta) (Ln = Yb, Y, Gd, Sm, Nd and La) proton-conducting ceramic materials are successfully prepared by solid-state reactive sintering method. The XRD analysis shows that the surface of ceramics is characterized by a pronounced texturing, whereas the volume of the same samples (obtained by grinding of ceramics) reveals the typical patterns. The degree of surface texture for BaCe(0.5)Zr(0.3)Ln(0.2)O(3-delta) (Ln = Yb, Y, Gd, Sm and Nd) samples is ranged between 24% and 39%, whereas for the BaCe0.5Zr0.3La0.2O3-delta ceramic it reaches 99%. The possible reason of particular texture of ceramics is proposed. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Characterization of proton-conducting electrolyte based on La0.9Sr0.1YO3-δ and its application in a hydrogen amperometric sensor

In the present study, a Sr-doped LaYO3 proton-conducting material is successfully synthesized by the citrate-nitrate combustion method and its phase features, microstructure, thermal behavior and transport properties are investigated by the aid of X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), dilatometry and four-probe dc electrical measurements. The set of the data obtained (single-phase structure, nonporous ceramic, low thermal expansion such as 10.5 × 10-6 K-1 and predominant ionic transport in oxidizing and reducing atmospheres even at 900 °C), allows one to propose this material as an electrolyte component for hydrogen amperometric sensors. To this purpose, a sensor, containing two electrochemical cells based on oxygen anionic YSZ and protonic La0.9Sr0.1YO3 - δ electrolytes, is constructed and its electrochemical properties are investigated under different conditions, including different H2 + N2 gas mixtures and temperatures. The possibility of direct measurement of hydrogen content in nitrogen on the base of the limiting current value is shown. It is found that the developed sensor exhibits good operation reproducibility, clear response and precision for the detection of trace hydrogen content (0.1-3.3 vol.%) in process gases at 500-600 °C. © 2015 Elsevier B.V. All rights reserved

The effect of y by Yb substitution in BaCe0.5Zr0.3Y0.2O3-Δ on the target properties of proton-conducting electrolytes

The BaCe0.5Zr0.3Y0.2-xYbxO3-δ ceramic materials are prepared and characterized in the present work. The impact of the partial Y3+/Yb3+ substitution on i) crystal structure, ii) microstructure (relative density, grain size), iii) thermal properties (linear expansion, thermal expansion coefficient) and iv) electrical properties (nature and value of conductivity) is identified. The BaCe0.5Zr0.3Y0.1Yb0.1O3-δ possesses high density, high conductivity, but relative low thermal expansion coefficient