Energies

Research

22 pages, 5973 KiB

Open AccessArticle

Developing an Automated Tool for Quantitative Analysis of the Deconvoluted Electrochemical Impedance Response of a Solid Oxide Fuel Cell

by Mohammad Alboghobeish, Andrea Monforti Ferrario, Davide Pumiglia, Massimiliano Della Pietra, Stephen J. McPhail, Sergii Pylypko and Domenico Borello

Energies 2022, 15(10), 3702; https://doi.org/10.3390/en15103702 - 18 May 2022

Cited by 3 | Viewed by 2024

Abstract

Despite being commercially available, solid oxide fuel cell (SOFC) technology requires further study to understand its physicochemical processes for diagnostics, prognostics, and quality assurance purposes. Electrochemical impedance spectroscopy (EIS), a widely used characterization technique for SOFCs, is often accompanied by the distribution of [...] Read more.

Despite being commercially available, solid oxide fuel cell (SOFC) technology requires further study to understand its physicochemical processes for diagnostics, prognostics, and quality assurance purposes. Electrochemical impedance spectroscopy (EIS), a widely used characterization technique for SOFCs, is often accompanied by the distribution of relaxation times (DRT) as a method for deconvoluting the contribution of each physicochemical process from the aggregated impedance response spectra. While EIS yields valuable information for the operation of SOFCs, the quantitative analysis of the DRT and its shifts remains cumbersome. To address this issue, and to create a replicable benchmark for the assessment of DRT results, a custom tool was developed in MATLAB to numerically analyze the DRT spectra, identify the DRT peaks, and assess their deviation in terms of peak frequency and DRT amplitude from nominal operating conditions. The preliminary validation of the tool was carried out by applying the tool to an extensive experimental campaign on 23 SOFC button-sized samples from three production batches in which EIS measurements were performed in parametric operating conditions. It was concluded that the results of the automated analysis via the developed tool were in accordance with the qualitative analysis of previous studies. It is capable of providing adequate additional quantitative results in terms of DRT shifts for further analysis and provides the basis for better interoperability of DRT analyses between laboratories. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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16 pages, 4144 KiB

Open AccessArticle

Investigation of a Metallic Interconnect Extracted from an SOFC Stack after 40,000 h of Operation

by Paolo Piccardo, Roberto Spotorno and Christian Geipel

Energies 2022, 15(10), 3548; https://doi.org/10.3390/en15103548 - 12 May 2022

Cited by 9 | Viewed by 2443

Abstract

An in-depth investigation was performed on a metallic interconnect extracted from an SOFC stack operated for 40,000 h. The characterization was performed on the surface and the cross-section, paying attention to the evolution of the materials due to the interaction with the dual [...] Read more.

An in-depth investigation was performed on a metallic interconnect extracted from an SOFC stack operated for 40,000 h. The characterization was performed on the surface and the cross-section, paying attention to the evolution of the materials due to the interaction with the dual atmosphere of the stack under operating parameters. The interaction between materials (i.e., metal substrate, coatings and atmospheres) and stack components (i.e., current collectors and MIC) generated several modifications that affected the surface and, in some cases, the bulk of the interconnect. The careful metallographic preparation allowed for the performance of an intensive microscopical characterization of the cross-sections all along the interconnect profile, from the inlet to the outlet of the fuel stream. The formation of thermal grown oxides on both sides and their evolution were studied and described. The interconnect, after 40,000 h, was still suitable for operation, but the few bulk changes due to the diffusion of Ni and the TGO that formed at the fuel side suggest the introduction of fuel side coatings to increase the life expectations of the whole stack. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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21 pages, 16231 KiB

Open AccessArticle

Accelerated Stress Tests for Solid Oxide Cells via Artificial Aging of the Fuel Electrode

by Daria Vladikova, Blagoy Burdin, Asrar Sheikh, Paolo Piccardo, Milena Krapchanska, Dario Montinaro and Roberto Spotorno

Energies 2022, 15(9), 3287; https://doi.org/10.3390/en15093287 - 30 Apr 2022

Cited by 1 | Viewed by 2502

Abstract

Solid Oxide Cells (SOCs) are under intensive development due to their great potential to meet the 2030 targets for decarbonization. One of their advantages is that they can work in reversible mode. However, in respect to durability, there are still some technical challenges. [...] Read more.

Solid Oxide Cells (SOCs) are under intensive development due to their great potential to meet the 2030 targets for decarbonization. One of their advantages is that they can work in reversible mode. However, in respect to durability, there are still some technical challenges. Although the quick development of experimental and modeling approaches gives insight into degradation mechanisms, an obligatory step that cannot be avoided is the performance of long-term tests. Taking into account the target for a commercial lifetime is 80,000 h, experiments lasting years are not acceptable for market needs. This work aims to develop accelerated stress tests (ASTs) for SOCs by the artificial aging of the fuel electrode via redox cycling, which follows the degradation processes of calendar aging (Ni coarsening and migration). However, it can cause irreversible damage by the formation of cracks at the interface anode/electrolyte. The advantages of the developed procedure are that it offers a mild level of oxidation, which can be governed and regulated by the direct impedance monitoring of the Ni network resistance changes during oxidation/reduction on a bare anode sample. Once the redox cycling conditions are fixed and the anode/electrolyte sample is checked for cracks, the procedure is introduced for the AST in full-cell configuration. The developed methodology is evaluated by a comparative analysis of current voltage and impedance measurements of pristine, artificially aged, and calendar-aged button cells, combined with microstructural characterization of their anodes. It can be applied in both fuel cell and electrolyzer mode. The results obtained in this study from the electrochemical tests show that the artificially aged experimental cell corresponds to at least 3500 h of nominal operation. The number of hours is much bigger in respect to the microstructural aging of the anode. Taking into consideration that the duration of the performed 20 redox cycles is about 50 to 60 working hours, the acceleration factor in respect to experimental timing is estimated to be higher than 60, without any damaging of the sample. This result shows that the selected approach is very promising for a large decrease in testing times for SOCs. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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16 pages, 4587 KiB

Open AccessEditor’s ChoiceArticle

Hybrid Solid Oxide Fuel Cell/Gas Turbine Model Development for Electric Aviation

by Joshua A. Wilson, Yudong Wang, John Carroll, Jonathan Raush, Gene Arkenberg, Emir Dogdibegovic, Scott Swartz, David Daggett, Subhash Singhal and Xiao-Dong Zhou

Energies 2022, 15(8), 2885; https://doi.org/10.3390/en15082885 - 14 Apr 2022

Cited by 14 | Viewed by 3291

Abstract

A thermodynamic model was developed and validated to analyze a high-performance solid oxide fuel cell and gas turbine (SOFC-GT) hybrid power system for electric aviation. This study used a process simulation software package (ProMax) to study the role of SOFC design and operation [...] Read more.

A thermodynamic model was developed and validated to analyze a high-performance solid oxide fuel cell and gas turbine (SOFC-GT) hybrid power system for electric aviation. This study used a process simulation software package (ProMax) to study the role of SOFC design and operation on the feasibility and performance of the hybrid system. Standard modules, including compressor, turbine, heat exchanger, reforming reactor, and combustor were used from the ProMax tool suite while a custom module was created to simulate the SOFC stack. The model used an SOFC test data set as an input. Additional SOFC stack performance effects, such as pressure, temperature, and utilization of air and fuel, were added from open source data. System performance predictors were SOFC specific power, fuel-to-electricity conversion efficiency, and hybrid system efficiency. Using these input data and predictors, a static thermodynamic performance model was created that can be modified for different system configurations and operating conditions. Prior to creating the final aircraft performance model, initial demonstration models were developed to validate output results. We used the NASA SOFC model as a benchmark, which was created with their Numerical Propulsion System Simulator (NPSS) software framework. Our output results matched within 1% of both the NASA model and open source SOFC performance data. With confidence gained in the accuracy of this model, a 1-MW SOFC-GT hybrid power system was constructed for an aircraft propulsion concept. Overall hybrid system efficiencies of > 75% FTE were observed during standard 36,000 feet cruise flight conditions. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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19 pages, 6351 KiB

Open AccessArticle

Test and Modelling of Solid Oxide Fuel Cell Durability: A Focus on Interconnect Role on Global Degradation

by Roberto Spotorno, Fiammetta Rita Bianchi, Daniele Paravidino, Barbara Bosio and Paolo Piccardo

Energies 2022, 15(8), 2762; https://doi.org/10.3390/en15082762 - 9 Apr 2022

Cited by 4 | Viewed by 2543

Abstract

High-temperature fuel cells are a promising technology due to their high energy efficiency and low environmental impacts compared to conventional engines. Nevertheless, they have a limited lifetime which reduces the use to a few application fields. Among them, Solid Oxide Fuel Cells (SOFCs) [...] Read more.

High-temperature fuel cells are a promising technology due to their high energy efficiency and low environmental impacts compared to conventional engines. Nevertheless, they have a limited lifetime which reduces the use to a few application fields. Among them, Solid Oxide Fuel Cells (SOFCs) have had a recent development at the industrial level in two possible configurations: anode- and electrolyte-supported design. Considering the impossibility to experimentally distinguish the effects of every degradation mechanism on global cell performance, each layer should be tested singularly through ex situ tests and then assembled into a virgin cell to evaluate its role on the whole system by in situ tests. However, this procedure results as quite complex, and some further microstructural changes could occur during cell sintering. In order to overcome these constraints, the proposed approach paired ex situ experimental observations on a single element with modelling results on global SOFC. As a case study, CoMnO/Crofer22 APU and CuMnO/AISI 441 interconnect samples were tested, measuring their resistance variation for some hundreds of hours, followed by a detailed post-mortem microstructural analysis. Based on a previously validated local model, SIMFC (SIMulation of Fuel Cells), the durability of commercial anode- and electrolyte-supported cells was simulated, adding specific degradation functions only for the interconnects in order to highlight their influence on SOFC performance. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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20 pages, 5293 KiB

Open AccessArticle

Deeper Understanding of Ternary Eutectic Carbonates/Ceria-Based Oxide Composite Electrolyte through Thermal Cycling

by André Grishin, Manel Ben Osman, Haïtam Meskine, Valérie Albin, Virginie Lair, Michel Cassir and Armelle Ringuedé

Energies 2022, 15(7), 2688; https://doi.org/10.3390/en15072688 - 6 Apr 2022

Cited by 4 | Viewed by 2427

Abstract

Due to a high conductivity of about 0.1 S·cm⁻¹, Li-Na-K carbonate eutectic and Sm-doped ceria composite material is a good electrolyte candidate for hybrid fuel cells operating between 500 °C and 600 °C. The present paper aims at a deeper understanding [...] Read more.

Due to a high conductivity of about 0.1 S·cm⁻¹, Li-Na-K carbonate eutectic and Sm-doped ceria composite material is a good electrolyte candidate for hybrid fuel cells operating between 500 °C and 600 °C. The present paper aims at a deeper understanding of the species and mechanisms involved in the ionic transport through impedance spectroscopy and thermal analyses, in oxidizing and reducing atmospheres, wet and dry, and during two heating/cooling cycles. Complementary structural analyses of post-mortem phases allowed us to evidence the irreversible partial transformation of molten carbonates into hydrogenated species, when water and/or hydrogen are added in the surrounding atmospheres. Furthermore, this modification was avoided by adding CO₂ in anodic and/or cathodic compartments. Finally, a mechanistic model of such composite electrical behavior is suggested, according to the surrounding atmospheres used. It leads to the conclusions that cells based on this kind of electrolyte would preferably operate in molten carbonate fuel cell conditions, than in solid oxide fuel cell conditions, and confirms the name of “Hybrid Fuel Cells” instead of Intermediate Temperature (or even Low Temperature) Solid Oxide Fuel Cells. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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17 pages, 4290 KiB

Open AccessArticle

Impact of Preparation Method and Y₂O₃ Content on the Properties of the YSZ Electrolyte

by Michal Carda, Nela Adamová, Daniel Budáč, Veronika Rečková, Martin Paidar and Karel Bouzek

Energies 2022, 15(7), 2565; https://doi.org/10.3390/en15072565 - 1 Apr 2022

Cited by 6 | Viewed by 2783

Abstract

This study is an effort to cover and interconnect multiple aspects of the fabrication of the yttria-stabilized zirconia (YSZ) from powder preparation to a solid electrolyte suitable for utilization in solid oxide cells. Thus, a series of YSZ electrolytes was prepared, differing in [...] Read more.

This study is an effort to cover and interconnect multiple aspects of the fabrication of the yttria-stabilized zirconia (YSZ) from powder preparation to a solid electrolyte suitable for utilization in solid oxide cells. Thus, a series of YSZ electrolytes was prepared, differing in the content of the Y₂O₃ dopant and in the method of preparation. Combustion synthesis along with the thermal decomposition of precursors was used for YSZ powder synthesis with a dopant content of 8 to 18 mol.%. Post-synthesis treatment of the powder was necessary for achieving satisfactory quality of the subsequent sintering step. The morphology analyses of the YSZ powders and sintered electrolytes produced proved that small particles with a uniform size distribution are essential for obtaining a dense electrolyte. Furthermore, the conductivity of YSZ electrolytes with different Y₂O₃ contents was examined in the temperature range of 400 to 800 °C. The lowest conductivity was found for the sample with the highest Y₂O₃ content. The obtained results enable the preparation methods, YSZ powder morphology, and composition to be connected to the mechanical and electrochemical properties of the YSZ electrolyte. Thus, this study links every step of YSZ electrolyte fabrication, which has not been sufficiently clearly described until now. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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12 pages, 4795 KiB

Open AccessArticle

Metal Supported Electrolysis Cells

by Anke Hagen, Riccardo Caldogno, Federico Capotondo and Xiufu Sun

Energies 2022, 15(6), 2045; https://doi.org/10.3390/en15062045 - 10 Mar 2022

Cited by 17 | Viewed by 4298

Abstract

Solid oxide electrolyser (SOE) technology can become a key player in energy systems, with increasing shares of electricity from fluctuating sources such as wind and solar, contributing to power grid balance and energy storage as well as providing green fuels for transportation. Most [...] Read more.

Solid oxide electrolyser (SOE) technology can become a key player in energy systems, with increasing shares of electricity from fluctuating sources such as wind and solar, contributing to power grid balance and energy storage as well as providing green fuels for transportation. Most mature SOE configurations are electrolyte supported or fuel electrode supported. Metal supported SOE cell configurations are an interesting concept for decreasing costs and increasing robustness. The present study compares fuel electrode supported and metal supported cells in terms of performance and durability under SOE conditions. Special emphasis was on medium temperature operating conditions of 650 °C. Metal supported cells, fabricated using ceramic processing methods, showed a better performance compared to state-of-the-art (SoA) cells with Ni/YSZ fuel electrode supported configuration, fabricated by tape casting and screen printing, under steam electrolysis conditions at 700 and 650 °C. The area specific cell resistance (ASR) was lower by ca. 20% for the metal supported cell in 50% H₂O in H₂ vs. air at 650 °C. Furthermore, the metal supported cells showed a stable performance—even a slight activation—during long-term steam electrolysis tests over 500 h at 650 °C and −0.25 and −0.5 A/cm², while the SoA reference cell degraded with 13%/1000 h under the same conditions. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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25 pages, 3092 KiB

Open AccessArticle

Parametric Thermo-Economic Analysis of a Power-to-Gas Energy System with Renewable Input, High Temperature Co-Electrolysis and Methanation

by Maria Alessandra Ancona, Vincenzo Antonucci, Lisa Branchini, Francesco Catena, Andrea De Pascale, Alessandra Di Blasi, Marco Ferraro, Cristina Italiano, Francesco Melino and Antonio Vita

Energies 2022, 15(5), 1791; https://doi.org/10.3390/en15051791 - 28 Feb 2022

Cited by 2 | Viewed by 1976

Abstract

A complete thermo-economic analysis on a cutting-edge Power-to-Gas system that comprises innovative technologies (a Solid Oxide Electrolyte Cell co-electrolyzer and an experimental methanator) and coupled with a renewable generator is provided in this study. The conducted economic analysis (which has never been applied [...] Read more.

A complete thermo-economic analysis on a cutting-edge Power-to-Gas system that comprises innovative technologies (a Solid Oxide Electrolyte Cell co-electrolyzer and an experimental methanator) and coupled with a renewable generator is provided in this study. The conducted economic analysis (which has never been applied to this typology of system) is aimed at the estimation of the synthetic natural gas cost of a product through a cash flow analysis. Various plant configurations—with different operating temperatures and pressure levels of the key components (electrolyzer: 600–850 °C; 1–8 bar)—are compared to identify possible thermal synergies. Parametric investigations are performed, to assess both the effect of the thermodynamic arrangements and of the economic boundary conditions. Results show that the combination of a system at ambient pressure and with a thermal synergy between the co-electrolyzer and the high-temperature methanator presents the best economic performance (up to 8% lower synthetic natural gas value). The production cost of the synthetic natural gas obtained by the Power-to-Gas solutions in study (up to 80% lower than the natural gas price) could become competitive in the natural gas market, if some techno-economic driving factors (proper size ratio of the storage system and the renewable generation, electrolytic cell cost developments and introduction of a carbon tax) are considered. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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17 pages, 9296 KiB

Open AccessArticle

Influence of the Contamination of Fuel with Fly Ash Originating from Biomass Gasification on the Performance of the Anode-Supported SOFC

by Marek Skrzypkiewicz, Michal Wierzbicki, Stanislaw Jagielski, Yevgeniy Naumovich, Konrad Motylinski, Jakub Kupecki, Agnieszka Zurawska and Magdalena Kosiorek

Energies 2022, 15(4), 1469; https://doi.org/10.3390/en15041469 - 17 Feb 2022

Cited by 1 | Viewed by 2040

Abstract

The integration of solid oxide fuel cells (SOFCs) with biomass gasification reactors raises the possibility of solid particle contamination of the gaseous fuel entering the cell. Technical specifications from SOFC manufacturers, among other sources, claim that SOFCs do not tolerate the presence of [...] Read more.

The integration of solid oxide fuel cells (SOFCs) with biomass gasification reactors raises the possibility of solid particle contamination of the gaseous fuel entering the cell. Technical specifications from SOFC manufacturers, among other sources, claim that SOFCs do not tolerate the presence of solid particles in fuel. However, there is very limited literature on the experimental investigation of feeding SOFCs with particulate matter aerosols. In this study, a standard 5 × 5 cm anode-supported SOFC was fueled by two types of aerosols, namely, (1) inert powder of grain sizes and concentration equivalent to gasifier fly ash and (2) a real downdraft gasifier fly ash, both suspended in a gaseous fuel mixture. For reference, cells were also investigated with a dust-free fuel gas of the same composition. A straightforward negative influence of the inert powder aerosol could not be confirmed in experiments with a duration of 6 days. That said, the introduction of carbonaceous fly ash aerosol caused slow but irreversible damage to the SOFC. The degradation mechanisms were studied, and the presence of carbon-containing particles was found to clog the pores of the SOFC anode. The maximum measured power density of the SOFC equaled 855 mW/cm² (850 °C, reference fuel). Feeding inert aerosol fuel caused no rapid changes in power density. A moderate drop in performance was observed throughout the experiment. The contamination of fuel with fly ash resulted in an initial performance gain and a ca. 25% performance drop longer term (43 h of contamination). Post-mortem analysis revealed contamination on the walls of the gas channels, with some visible alumina or fly ash spots in the anode area. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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24 pages, 7423 KiB

Open AccessArticle

Protective Coatings for Ferritic Stainless Steel Interconnect Materials in High Temperature Solid Oxide Electrolyser Atmospheres

by Jyrki Mikkola, Karine Couturier, Belma Talic, Stefano Frangini, Nathalie Giacometti, Nathalie Pelissier, Bhaskar Reddy Sudireddy and Olivier Thomann

Energies 2022, 15(3), 1168; https://doi.org/10.3390/en15031168 - 5 Feb 2022

Cited by 11 | Viewed by 3276

Abstract

Stainless steel interconnect materials used in solid oxide fuel cells and electrolysers need to be coated to improve oxidation resistance and to mitigate Cr-vaporization. This work aimed to explore the optimal steel/coating combinations suitable for use in reversible solid oxide stacks and evaluated [...] Read more.

Stainless steel interconnect materials used in solid oxide fuel cells and electrolysers need to be coated to improve oxidation resistance and to mitigate Cr-vaporization. This work aimed to explore the optimal steel/coating combinations suitable for use in reversible solid oxide stacks and evaluated (Co,Mn)₃O₄ spinel, LaFeO₃ perovskite, Ce/Co and Y-based coatings, on AISI441 and Crofer 22 APU steels. The coatings were evaluated based on measurements of mass gain and oxide scale thickness after exposure at 700 and 800 °C to fuel side (90 vol.% H₂O/10 vol.% H₂) and air/oxygen side (pure O₂) atmospheres. In pure O₂, the most efficient coatings for limiting oxide scale formation and Cr evaporation, compared to the bare steel, were (Co,Mn)₃O₄ and CeCo on Crofer 22 APU. In 90 vol.% H₂O/10 vol.% H₂, the Y-based coating showed the largest improvement in oxidation resistance. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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10 pages, 2072 KiB

Open AccessArticle

Nondestructive Testing of the Integrity of Solid Oxide Fuel Cell Stack Elements by Ultrasound and Thermographic Techniques

by Udo Netzelmann, Andrea Mross, Thomas Waschkies, Dietmar Weber, Ewald Toma and Holger Neurohr

Energies 2022, 15(3), 831; https://doi.org/10.3390/en15030831 - 24 Jan 2022

Cited by 2 | Viewed by 2526

Abstract

Single planar fuel cell elements consisting of metallic interconnectors that are bonded and sealed by a thin glass solder layer form the core of a solid oxide fuel cell. For reliable operation, the bonding layer has to adhere well and must be without [...] Read more.

Single planar fuel cell elements consisting of metallic interconnectors that are bonded and sealed by a thin glass solder layer form the core of a solid oxide fuel cell. For reliable operation, the bonding layer has to adhere well and must be without voids or foreign material inclusions, which might cause gas leakage, electrical shorts or mechanical weakening and structural failure. Nondestructive testing (NDT) by the high-frequency ultrasound in immersion technique and by air-coupled ultrasound was optimized to find such defects. Another technique was flash light excited thermography for detection of voids. The NDT techniques used are complementary to each other, as they are based on different physical principles. Voids and small steel platelets of different sizes were prepared in the glass solder layer before the high-temperature bonding process and then monitored by the NDT techniques through the interconnector plates. Two selected NDT techniques were then validated in a probability of detection (POD) study. The study resulted in detection limits for the two main types of defects. As a step towards production testing, a demonstrator was built combining testing by air-coupled ultrasound and that by flash thermography. During the testing steps, the cell elements were handled by a collaborative robot. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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11 pages, 2639 KiB

Open AccessArticle

Preparation and Electrical Properties of Sr-Doped LaFeO₃ Thin-Film Conversion Coatings for Solid Oxide Cell Steel Interconnect Applications

by Stefano Frangini, Livia Della Seta and Claudia Paoletti

Energies 2022, 15(2), 632; https://doi.org/10.3390/en15020632 - 17 Jan 2022

Cited by 7 | Viewed by 1929

Abstract

A study was conducted to explore the effects of Sr doping on the electrical properties of perovskite LaFeO₃ thin-film protective conversion coatings grown onto a K41 ferritic stainless steel, a typical interconnect material for intermediate temperature solid oxide cell (SOC) applications. The [...] Read more.

A study was conducted to explore the effects of Sr doping on the electrical properties of perovskite LaFeO₃ thin-film protective conversion coatings grown onto a K41 ferritic stainless steel, a typical interconnect material for intermediate temperature solid oxide cell (SOC) applications. The Sr-doped coatings were prepared in La₂O₃- and SrO-containing molten carbonate baths with minor added amounts of nitrate salt for accelerated coating formation. For comparison purposes, undoped coatings were obtained using the same carbonate bath, with the only difference being that SrO was replaced by inert MgO. SEM/EDX and XRD analyses were used for coating characterization and confirmed the effective incorporation of Sr but not of Mg into the LaFeO₃ layer. Although both the Sr-doped and undoped coatings consisted of a LaFeO₃ layer grown above an inner Fe-Cr spinel, the coating thickness of the Sr-doped coating was distinctly higher, approximately 2 µm, which is twice that of the undoped coating. Electrical measurements in terms of Area-Specific Resistance (ASR) were conducted at 700 °C in air and showed that Sr-doping significantly improved the electrical conductivity of the coated K41 steel. Due to the Sr-doping, the ASR values of the coated steel dropped from 60 to 37 mΩ cm² after 300 h of exposure, in spite of the higher Sr-doped coating thickness. The study concludes that Sr-doped thin-film perovskite coatings appear to be a promising solution for improved SOCs steel interconnect stability at intermediate temperatures. Full article

(This article belongs to the Special Issue Solid Oxide Cells: Technology, Design and Applications)

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