bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of the Influences of Fuel Utilization on Efficiency and Anode Safety at Different Fuel Flow Rates for Industrial-Size Solid Oxide Fuel Cell
Authors: Wang Yige , Lyu Zewei , Li Hangyue , Han Minfang
Published: September 2023

Solid oxide fuel cell (SOFC) is regarded as a promising energy conversion technology that can directly produce electricity from chemical fuels without combustion. Commercialization of SOFC systems has already started with residential and industrial applications, and demonstrations for a broader range of uses have been carried out. However, the widespread commercialization of SOFC systems requires further improvements both in efficiency and durability. The efficiency of a single cell is affected by fuel utilization and voltage. In addition, high fuel utilization may cause an increase in concentration polarization or lead to local Ni oxidation of cell anode. Therefore, it is imperative to study the influence of fuel utilization on the cell's performance, efficiency, and anode safety. In this work, I-V curves at different fuel flow rates were tested. The fuel utilization and voltage corresponding to the peak power density at different flow rates were determined. Based on the gas conversion and diffusion resistance models, the area specific resistance behavior and the fuel utilization corresponding to the beginning of the concentration polarization zone were investigated. Besides, the effects of fuel utilization and cell voltage on local Ni oxidation were also studied. The results indicated that at a low fuel flow rate of 0.1-0.3 L/min, the fuel utilization corresponding to the peak power density condition (which is also the condition of maximum efficiency) was about 90%. Although a significant increase in concentration polarization occurred under such high fuel utilization, no Ni oxidation occurred due to the high voltage. However, at a high fuel flow rate of 0.8-1.0 L/min, the fuel utilization corresponding to the peak power density condition was about 70%. The low voltage led to local Ni oxidation before entering the concentration polarization zone. This finding provides an idea for choosing fuel utilization at different fuel flow rates to realize high efficiency and anode safety.
Commercialization of Ceres SteelCell® Technology for Power Generation and Electrolysis
Authors: Leah Robert , Bone Adam , Hjalmarsson Per , Selcuk Ahmet , Lankin Mike , Rahman Mahfujur , Felix Florence , De Vero Jeffrey , Macauley Chandra , Charbonneau Cecile , Rios Laura , Mukerjee Subhasish , Hargrove Caroline , Selby Mark
Published: September 2023

Ceres’ unique metal supported SOC technology is increasingly establishing itself as the global standard for SOC, combining robustness, efficiency and low manufacturing cost. The technology is rapidly moving from demonstration to true volume production, with Robert Bosch GmbH in Germany and Doosan Fuel Cell in South Korea both having licenses to manufacture Ceres SteelCell® cells and stacks at the hundreds of MW per year scale with factories under construction. Ceres currently have manufacturing plants making MW of stacks per year. Ceres SteelCell® technology has a wide range of applications in the power generation sector, with applications ranging from small scale <10kWe combined heat and power (CHP) systems to systems in the 100s of kW to MW range. An increasing area of interest for the application of SteelCell® technology is in the difficult-to-decarbonize marine sector, where the ability to operate efficiently on a range of fuels with much lower carbon emissions than the heavy diesel normally used for shipping. These include liquefied natural gas (LNG), methanol and liquid ammonia, as well as hydrogen. This is also driving development of higher-power systems in the MW range.

An exciting new development is the application of Ceres SteelCell® technology to steam electrolysis. The inherent advantages of Ceres SteelCell® in terms of mechanical robustness, REDOX stability, low production cost and low-cost balance of plant are also applicable to electrolysis applications. In addition, there are potential thermodynamic advantages for integration of high temperature electrolysis with other industrial processes to utilize waste heat stemming from the lower temperature of operation of Ceres SteelCell® technology relative to competing SOC technologies as lower-grade heat is required. To demonstrate the capability of Ceres SteelCell® for electrolysis Ceres is developing a 1MWe-class steam electrolyzer demonstrator using a modular architecture of multiple smaller electrolysis cell modules (ECMs) which can operate standalone. Testing and validation of ECMs is currently ongoing prior to full system integration. These ECMs are built into a standard 40ft shipping container to form the complete system.

Ceres has recently signed an agreement with Shell to operate one of these 1MW-class systems at Shell’s R&D center in Bangalore, India running for 3 years from 2023. In addition to gaining valuable experience in plant operation the hydrogen generated will be used for industrial processes on the site.
Protonic Ceramic Electrochemical Cells with Dry Reforming of Methane for Electricity Generation, Chemicals Manufacturing, and Greenhouse Gas Mitigation
Authors: Liu Fan , Duan Chuancheng
Published: September 2023

The massive exploration and utilization of fossil fuels for power generation and chemicals manufacturing have contributed to worldwide economic growth. However, these activities lead to significant greenhouse gas (GHG) emissions, which primarily include CO2 and CH4. The technologies, which intensify power generation with chemicals production from CO2 and CH4, will reduce the carbon footprint and address associated challenges. Dry reforming of methane (DRM, CH4 + CO2→ 2CO + 2H2) in electrochemical devices, which converts both CO2 and CH4 to a mixture of CO and H2 (i.e., syngas), and electricity, could be leveraged to achieve simultaneous power generation, chemicals manufacturing, and GHG mitigation. In this talk, we will present our novel protonic ceramic electrochemical cells (PCECs) for achieving this objective. The current PCECs with internal DRM suffer from poor performance, high operating temperature, and short durable operation, which is mainly ascribed to the lack of highly active and coking tolerant DRM catalysts that could be chemically and physically compatible with PCECs. This talk with present an oxide-supported in-situ exsolved Ni-Ru catalyst, which has been carefully designed and computationally validated as a highly active and coking-tolerant DRM catalyst. This DRM catalyst significantly enhances the catalytic activity and coking tolerance, which consequently lowers the operating temperatures of PCECs, with excellent fuel cell performance durability demonstrated. An exceptional peak power density of 0.94, 0.65, and 0.30 W cm-2 has been attained at 650 °C, 600 °C, and 550 °C, respectively, setting a record of PCECs for DRM.
Protonic Ceramic Fuel Cells with Stoichiometric Electrolytes
Authors: Choi Mingi
Published: September 2023

Among various types of solid oxide electrochemical cells, protonic ceramic fuel cells (PCFCs) have been expected to reduce the operating temperature below 600 °C with their significantly high ionic conductivity and activation energy. For example, recently developed proton conductor (BaZr0.4Ce0.4Y0.1Yb0.1O3-δ, BZCYYb) ideally has ~12-fold higher ionic conductivity (2.810-2 S/cm at 600 °C) and low activation energy (Ea < 0.4 eV) than those of conventional oxide ion conductor (Y0.08Zr0.92O2-δ; 2.810-3 S/cm at 600 °C and Ea ~0.87 eV). However, the low chemical and physical stabilities of proton conducting oxides during fabrication processes, primarily due to the high mobility and volatility of Barium (Ba), induce the substantially lower electrochemical performance than their predictions, limiting their utilization and application. Here, we present the chemically and physically stable BZCYYb electrolyte with the desired stoichiometry and the average grain size of ~10 µm by controlling the chemical potential of the A-site cation, Ba, near the BZCYYb electrolyte surface during the sintering process. A stoichiometric BZCYYb-based PCFC in an anode-supported configuration exhibits 1.90/cm2 and 1.01 W/cm2 with an extremely low ohmic resistance of ~0.060 ohm·cm2 at 650 °C and ~0.082 ohm·cm2 at 550 °C, respectively. Our results may open the possibility of finding a technical breakthrough for various next-generation electrochemical systems having desirable material properties without the requirement for complicated and expensive fabrication processes.
Electrochemical Activity and Stability of Pure Gadolinium Doped Ceria as Fuel Electrode in Solid Oxide Electrolysis Cells
Authors: Uecker Jan , Unachukwu Ifeanyichukwu Daniel , Vibhu Vaibhav , Vinke Izaak , Eichel Rudiger-A , de Haart L.G.J. (Bert)
Published: September 2023

The state-of-the-art fuel electrode materials for solid oxide electrolysis cells (SOECs) are Ni-cermets due to their high electro-catalytic activity, high electrical conductivity and the low price. However, one major concern that must be solved for a widespread commercialisation is their poor degradation behaviour during electrolysis operation caused by for example Ni migration, depletion and agglomeration in the fuel electrode. One strategy to improve the durability of SOECs is the usage of alternative fuel electrode materials. For instance, completely Ni-free fuel electrodes may solve the problems of morphological degradation during operation and further could enhance redox cycling stability. Within possible candidates, gadolinium doped ceria (GDC) is an interesting material due to good stability towards carbon deposition and the possibility to host electro catalysis in electrolysis reactions [1, 2]. Furthermore, GDC (Ce0.8Gd0.2O2-δ) shows electronic conducting (700 °C, 0.028 S·cm-1) and ionic conducting (700 °C, 0.47 S·cm-1) properties at low partial pressures of oxygen and high temperatures [3]. Hence, in this work we have prepared electrolyte supported single cells with GDC (Ce0.8Gd0.2O2-
δ) as single phase fuel electrode for their use as SOEC. The single cells (GDC//8YSZ//GDC//LSCF) were characterized by electrochemical impedance spectroscopy (EIS) and current-voltage characteristics in steam electrolysis, co-electrolysis and CO2 electrolysis conditions exhibiting 70 % of the performance compared to similar produced Ni-GDC fuel electrode single cells at 900 °C [4]. Furthermore, the results include process analysis by EIS, long term stability experiments for steam electrolysis and CO2 electrolysis conditions of at least 1000 hours and post characterization of the degraded cells by EIS, SEM and EDX analysis.

[1] Nakmura et al. Journal of the Electrochemical Society
155 (2008) B563.

[2] Chueh et al. Nature Materials
11 (2012) 155-161.

[3] Maricle et al. Solid State Ionics
52 (1992) 173-182.

[4] Unachukwu et al. Journal of Power Sources
556 (2023) 232436.

Figure 1
Addressing the Timing Imbalance between Renewable Energy Generation and Use: Reversible Solid Oxide Cells Based on Rare-Earth Nickelate Oxygen Electrodes
Authors: Akter Ayesha , Mulligan Jillian Rix , Lee John-In , Basu Soumendra , Pal Uday , Gopalan Srikanth
Published: September 2023

Incorporating more renewable energy into our economy will require us to address the timing imbalance between renewable energy generation and its use. Reversible solid oxide cells which have the ability to be dynamically load cycled between electrolysis mode when renewable energy availability is plentiful, and fuel cell mode when stored energy needs to be used, offer a potential solution. In this work, we have fabricated solid oxide cells featuring a neodymium nickelate based oxygen electrode, nickel – yttria stabilized zirconia (YSZ) fuel electrodes, and YSZ solid electrolyte. The cells have been electrochemically characterized in electrolysis and fuel cells mode, as well as in dynamic load cycling mode for a period of five hundred hours. The cells were characterized by both DC polarization and AC impedance spectroscopy methods. Distribution of relaxation times (DRT) analysis of the impedance data reveal significant details about the mechanisms underlying degradation in electrolysis and dynamic cycling modes, and are strongly linked to microstructural changes in the fuel electrode. Further, the dynamic cycling experiments clearly reveal that operating the cells in the dynamic cycling mode mitigates against degradation that occurs when the cells are operated in electrolysis mode. These results strongly suggest that storage systems featuring stacks of such reversible solid oxide cells may offer a path forward to solving the timing imbalance of renewable energy generation and use.
A Simple Preparation of Electrolyte Powder for Stoichiometric Electrolyte in Protonic Ceramic Cells
Authors: Kim Junseok , Nahm Sahn , Lee Jong-Ho , Ji Ho-il
Published: September 2023

Among various eco-friendly energy conversion technologies, solid oxide cells (SOCs) exhibit superior energy conversion efficiency and performance owing to the kinetic and thermodynamic advantages. Recently, protonic ceramic cells (PCCs) have begun to attract attention with expectation that the operating temperature of SOCs can be lowered around 500oC, thereby achieving better durability with maintaining higher conversion efficiency. However, the promising proton conducting electrolytes in PCCs are mostly Ba-containing perovskites exhibiting highly refractory property, thus substantially have challenges associated with barium volatilization during high-temperature sintering process. At the same time, Ni-containing transient phases generated at the electrode and supplied to the electrolyte during sintering of electrode/electrolyte bilayer not only facilitate the sintering of electrolyte, but also induce the compositional change owing to the residue thereof. Such off-stoichiometry indeed degrades the electrical properties, and thus most of all reported performance of PCCs could not fully reflect the intrinsic property of electrolytes.

Here, we describe a simple but effective strategy to realize the highly conductive electrolyte in PCCs via suppression of barium volatilization as well as minimization of supplied amount of transient phases; a low-temperature calcination process. The electrolyte powder calcined at the relatively lower temperature, which is high enough to react all the precursors without residue, but low enough to suppress the Ba volatilization. The PCCs fabricated using this low-temperature calcined electrolyte powder shows the reduced ohmic resistance, and in turn, enhanced electrochemical performance. While the research on PCCs, up to now, have mainly been focused on processing technique or new materials for the better performance, the result of this study implies that the status of initial electrolyte powder can significantly influence the overall cell characteristics.
Ni / GDC Fuel Electrode for Low Temperature SOFC and its Aging Behavior under Accelerated Stress
Authors: Liu Yanting , Juckel Martin , Menzler Norbert H. , Weber Andre
Published: September 2023

For the increase of the number of the potential applications of SOCs as well as a lower system cost, realization of operating at lower temperatures (< 650 °C) is a key point. However, the overall cell performance would decrease dramatically with reduction in temperature because of reducing ionic conductivity in electrolyte and increased polarization resistance from both electrodes. In case of realizing high performance yet also good mechanical stability, wet infiltration is shown to be one effective method [1].

In this contribution, the concept of infiltration is presented with a GDC infiltrated Ni-Skeleton fuel electrode. With this approach, a polarization resistance of below 0.2 Ω cm² at 600 °C is realized. To study the durability of such electrode, the concept of accelerated testing is applied. Symmetrical cells are tested to avoid an additional impact of the air electrode [2]. The cells are operated at temperatures up to 900 °C and a high steam content of 50 % for up to 1000 h. Electrochemical impedance spectroscopy (EIS) is employed to record the temporal development of the electrode performance. By means of the distribution of relaxation times (DRT), the temporal evolution of the loss processes is identified. As an example, impedance and DRT at 600 °C before and after aging at 900 °C for 650 h is presented in Figure 1(c). Microstructural analysis of electrode in different aging status is carried out with optical- and electron microscopy. The initially nanoscaled microstructure of the infiltrated GDC, as presented in Figure 1(a), is agglomerated (Figure 1(b)) during aging at elevated temperatures, which is in agreement with the observed increase in polarization resistance.

Keywords

Solid Oxide Fuel Cell; low temperature; porous electrodes; accelerated life time test; aging phenomenon; GDC; SEM

[1] Z. Liu.et al., J. Power
Sources, 237, p. 243 (2013)

[2] C. Endler-Schuck.et al., J. Power Sources, 196 (17), p. 7257 (2011).

[3] S. Dierickx.et al., Electrochim
ica
Acta, 355, p. 136764 (2020).

[4] A. Weber, tm - Technisches Messen, 88 (1), p. 1 (2021).

[5] C. Grosselindemann.et al., ECS Trans., 103 (1), p. 1375 (2021).

Figure 1
Additive Manufacturing of Single-Layer Protonic Ceramic Fuel Cells
Authors: Asghar Muhammad Imran , Lund Peter D.
Published: September 2023

Protonic ceramic fuel cells (PCFCs) or proton conducting solid oxide fuel cells (p-SOFCs) have been emerging as a potential low-temperature (400-600oC) fuel cell technology. Generally, the proton conducting ceramic electrolyte materials have a lower activation energy (< 50 eV) and lower electronic conductivity than the conventional oxygen-ion conducting ceramic materials, which are beneficial for improving the fuel cell efficiency and the power output. The additive manufacturing has the potential to transform the manufacturing of PCFCs since it can fabricate both the dense and porous structures with good mechanical and electrochemical properties. In this work, we fabricated single-layer PCFCs through a hybrid of extrusion-based 3D printing utilizing BaZr0.3Ce0.5Y0.15O3-δ and BaZr0.4Ce0.4Y0.1Yb0.1O3-δ as electrolytes, their composite with NiO as anode, and their composite with BaCo0.4Fe0.4Zr0.1Y0.1O3-δ and Ba0.5Sr0.5Co0.8Fe0.2O3-δ as cathode. The rheological properties of the printable pastes were investigated in detail with the dynamic light scattering, viscometer, tensiometry, differential scanning calorimetry and thermal gravimetric analysis. Furthermore, the cells are characterized with current-voltage measurements and electrochemical impedance spectroscopy. In addition, other spectroscopic and microscopic measurements (HR-TEM-EELS, SEM-EDX, XPS) were conducted to better understand the mechanisms in the cells. A systematic study was conducted to optimize the sintering temperature for optimal fuel cell performance. Finally, the degradation mechanisms in the cells were investigated in order to improve their stability.

Dr. Asghar thanks Academy of Finland (Grant No. 13322738, 13329016, 13352669) for the financial support.

Figure 1
Accelerated Stress Testing of Standard Solid Oxide Electrolysis Cells
Authors: Kane Nicholas , Hartvigsen Jeremy , Casteel Micah , Priest Cameron , Gomez Joshua , Wang Lucun , White Casey , Boardman Richard , Ding Dong
Published: September 2023

The production of clean and sustainable hydrogen via the commercialization of solid oxide electrochemical cells (SOECs) is currently limited by high cell degradation rates leading to increased costs. In order to achieve the U.S. DOE’s goal of producing hydrogen at $1 kg-1 by 2030, a thorough understanding of the critical degradation mechanisms and their relationship to the SOEC operating conditions is required. To elucidate these mechanisms, accelerated stress testing of standardized Ni-YSZ|YSZ|GDC|LSCF electrolysis cells is being investigated by a National Laboratory Consortium. Initial work focused on the development and standardization of testing procedures including the glass seals, current collectors, and system configurations, leading to improved yield, uniformity, and process control. With a stable baseline, parametric testing of the cell operating conditions, including the temperature, supply voltage/current, and steam concentration, as well as the cycling of these conditions was performed to intentionally initiate and accelerate proven and less understood microstructural evolution mechanisms and modes of mechanical failures. Both ex-situ sample characterization and in-operando experiments are used to understand the evolution of potential degradation mechanisms, including elemental migration and secondary phase formation, void formation, interfacial segregation, and phase decomposition. By understanding the parameters and kinetics of the degradation processes, the Consortium expects to be able to project lifetime performance and cumulative degradation. Ultimately, this work will improve the fabrication and operation of SOECs and enable the production of low-cost hydrogen via water electrolysis.
BaCo0.4Fe0.4Zr0.1Y0.1O3-Σ Cathode Performance for Proton Conducting Solid Oxide Fuel Cells with BaZr0.8-XCexY0.1Yb0.1O3-Δ Electrolytes
Authors: Li Wenhao , Sozal Md Shariful Islam , Drozd Vadym , Durygin Andriy , Cheng Zhe
Published: September 2023

BaCo0.4Fe0.4Zr0.1Y0.1O3-σ (BCFZY) is a proton, oxygen-ion, and electron-hole triple conducting cathode material for solid oxide fuel cells. Its electrode reaction mechanism including the rate-limiting step in air with moisture are not well understood. Therefore, we fabricated three types of symmetric cells with the same BCFZY cathode over three related proton conducting electrolytes: BaZr0.8-xCexY0.1Yb0.1O3-δ (x = 0.1, 0.4, and 0.7; Fig.1 are SEM images showing the surface of three different electrolytes). The cathode shows different electrochemical behaviors for the three electrochemical cells including the response to the introduction of moisture. The differences are hypothesized to relate to mutual diffusion at the cathode/electrolyte interface, which are tested by various techniques such as XRD Rietveld refinement of BCFZY cathode in mixtures with different electrolytes after firing, thermogravimetric analysis (TGA) for oxygen vacancy concentration and hydration behavior, electrical conductivity relaxation (ECR) for conductivity changes between dry and moist atmosphere, and energy-dispersive X-ray spectroscopy (EDS) line scanning for element concentration distribution at the cathode/electrolyte interface.

Fig1. SEM images of electrolytes (a) BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (Ce-rich), (b) BaZr0.4Ce0.4Y0.1Yb0.1O3-δ (ZrCe-bal) and (c) BaZr0.7Ce0.1Y0.1Yb0.1O3-δ (Zr-rich)

Figure 1
Examination of Morphological and Chemical Properties of Ni-BZY Anodes and their Influence upon Methane Reactivity and Electrochemical Performance of Protonic-Ceramic Fuel Cells
Authors: Hadi Abdul-Sommed , Morrow Fiona , Kirtley John David
Published: September 2023

Protonic ceramic fuel cells (PCFCs) have recently emerged as potential alternatives to traditional solid oxide fuel cells due in part to their enhanced tolerance to performance losses caused by coking and sulfur poisoning. These advantages can be attributed to the unique cermet anode materials used in these devices. Ni-BZY (yttrium-doped barium zirconate) in particular has been widely investigated due to BZY’s superior protonic conductivity and stability in hydrocarbon reforming environments containing carbon dioxide and steam. In addition, Ni and BZY have been observed to form unique nano/microstructures thought to synergistically improve catalytic reforming. However, recent work suggest that at high temperatures (≥ 700 ˚C), the Ni-BZY anode suffers rapid deactivation when operated with steam reformed methane (SRM), but unfortunately the underlying reasons remain unclear. The objective of the present work is to elucidate how anode deactivation under SRM may be influenced by molecular surface structures (i.e. coke), as well as phase and morphological changes within the Ni-BZY anode. The PCFCs used in this work consist of a ~20 μm Ni-BZY anode sintered onto a ~600 μm BZY support complete with a composite cathode of lanthanum strontium cobaltite ferrite and ceria- and yttria-doped barium zirconate (LSCF/BCZY). The long-term electrochemical performance of these cells at OCV and under load is compared at 600 -700 °C while operating with SRM (1CH4:1H2O), neat methane, and humidified hydrogen. Further insights into the underlying morphological and chemical changes are provided by pre- and post-mortem analysis of the anode via Raman spectroscopy, X-ray diffraction, and SEM analysis.
NH3-Fed Patterned Electrode Solid Oxide Fuel Cell: Experimental Performance Characterization and Elementary Reaction Modeling
Authors: Liu Zerui , Shi Jixin , Wang Yuqing , Shi Yixiang , Cai Ningsheng
Published: September 2023

Ammonia-fueled solid oxide fuel cells (SOFCs) have attracted the focus of researchers due to the feature of no carbon emission. Understanding the reaction mechanism is vital for the design and optimization of NH3-fed SOFCs. However, the catalytic decomposition reactions involved in porous electrodes led to the difficulty to distinguish the anode reaction mechanism. In the present study, we utilized a patterned anode to get a designed triple phase boundary (TPB) and avoid the effects of porous electrodes. In the performance test, we found that the current density of the NH3-fed SOFC was approximately 20% of that of the H2-fed SOFC under a similar working position at 750℃. The difference may mainly resulted from the limit of catalytic decomposition of NH3 caused by the narrow reactive area in the patterned electrode. A one-dimensional elementary reaction model was further developed to validate this hypothesis and to provide additional evidence for the reaction mechanisms of the NH3-fed SOFC.
Three-Dimensional Microstructural Analysis for the Characterization of Failure Mechanisms of a Novel SOEC
Authors: Wehner Luzie , Lenser Christian , Dzieciol Krzysztof , Wessel Egbert , Malzbender Jürgen , Schwaiger Ruth
Published: September 2023

A novel Ni-GDC-cermet-supported intermediate temperature electrolysis cell that has been developed as promising candidate for hydrogen production with GDC as electrolyte, YSZ as electron-blocking layer and an additional GDC diffusion-blocking layer is characterized.

Although this three-layer GDC-YSZ-GDC electrolyte enables improved performance compared to state-of-the-art YSZ electrolyte-based cells especially at lower operation temperatures, at temperatures below 750 °C and high electrolysis currents a voltage drop and subsequently crack formation in the three-layer electrolyte was observed in initial studies.

Thus, in order to investigate the cause of this catastrophic cell failure a three-dimensional microstructural analysis of the cathode functional layer and electrolyte was conducted. Different methods were used to obtain detailed information on the microstructure and changes thereof. The methods used were FIB-SEM, X-ray computed tomography and laser confocal microscopy. By combining the results obtained from the different methods, a detailed understanding of the electrolyte/electrode microstructure was achieved. The analysis of a representative volume element via non-destructive X-ray computed tomography and FIB-SEM enabled the reconstruction of the microstructure and segmentation into a three-dimensional material distribution. Three-dimensional microstructures of cells before and after single-cell testing were analysed and compared. Additionally, laser confocal microscopy was used for a direct assessment of cracks and other defects. An overview of the advantages of the different characterization methods and findings will be given.
Development of Multiple Ceramic Coatings on Porous Tubular Metal Support
Authors: Sahu Sulata Kumari , Panthi Dhruba , Du Yanhai
Published: September 2023

Micro-tubular metal supported Solid Oxide Fuel Cell (MS-SOFC) has many advantages over traditional ceramic supported SOFC, such as greater mechanical robustness, better thermal and redox cycling along with low cost of starting material. Among the multiple MS-SOFC fabrication methods, the one involving sequential dip-coating followed by co-sintering has the potential to reduce the fabrication cost further, making it attractive from a commercial production standpoint. However, the co-sintering route is challenging because it requires constrained sintering conditions, high temperatures, and inert atmosphere. Other challenges with the co-sintering route are delamination and cracking of layers, warping of cell, diffusion of Fe and Cr away from metal support, diffusion of Ni from anode, coarsening of Ni in the anode, and lack of complete densification of YSZ electrolyte even at temperatures as high as 1350 °C.

In this work, we developed a new ceramic multilayer design on a porous tubular 3D-printed metal support. Scandia Stabilized Zirconia (SSZ) and, Ni and SSZ (Ni-SSZ cermet) were used as electrolyte and anode, respectively. Stainless steel 17-4 PH was identified as the metal support material due to its matching coefficient of thermal expansion with SOFC ceramic materials, low cost and corrosion resistance nature. The dip coating steps and the co-sintering process were optimized so that they could be adopted for a cost-effective fabrication of MS-SOFC. The binder-burnout step was optimized to prevent cracking of the multilayers during the co-sintering process. To avoid delamination and to impede the inter-diffusion of elements, a coating of an intermediate layer made of 17-4 PH stainless steel+Ni+YSZ was introduced between the metal support and the succeeding layers. Preliminary results suggest that the intermediate layer has a potential to prevent delamination and inter-diffusion. Introduction of the debinding step and optimized sintering profiles resulted in the formation of the uniform and dense electrolyte coating. However, certain cell warping was observed after electrolyte sintering, suggesting further improvement is still needed in the support design and ceramic processing.
Characterization of Sr2Fe1,5Mo0,5O6-δ Based Solid Oxide Electrolysis Cells
Authors: Salvan Laur Kristjan , Lust Enn , Nurk Gunnar , Möller Priit
Published: September 2023

Hydrogen electrodes of solid oxide electrolysis cells (SOEC) are typically made of Ni-YSZ cermet. Despite having excellent catalytic activity Ni-based electrodes suffer from poor redox stability and Ni volatility [1]. Sr2Fe1,5Mo0,5O6-δ (SFM) mixed ionic- and electric conducting (MIEC) double perovskite has been proposed as promising hydrogen electrode material for solid oxide electrolysis cells (SOEC) because of its excellent catalytic properties and good conductivity. In this study SOEC single cells were prepared using SFM hydrogen electrode and (La0,6Sr0,4)0,99Co0,96Ti0,04O3-δ (LSCT) as well as (La0.6Sr0.4)0.95Co0.2Fe0.8O3-δ (LSCF) air electrodes [2, 3].

Studied cells were prepared using 19 mm 10Sc1CeSZ electrolyte substrates. Screen printed 6 μm thick Ce0.9Gd0.1O1.95 (GDC) layer was applied to both sides of the cell to prevent formation of insulating SrZrO3 layer. GDC layer was sintered to the electrolyte at 1300°C for 5h. SFM or 50%SFM/50%GDC electrode layer with 0,52cm2 surface area was screen printed to the GDC layer and was sintered at 1200°C and at 1150°C to optimize electrode composition and thermal treatment program of electrode. Afterwards LSCT or LSCF oxygen electrodes were screen printed to the other side of the cell and sintered at 1100°C for 2 h. Finally, cells were characterized using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and time-of flight secondary ion mass spectrometry (TOF-SIMS).

Impedance spectroscopy analysis showed that cells with 50%SFM/50%GDC hydrogen electrode sintered at 1150°C and LSCT oxygen electrode had highest current densities, reaching 1,59 A/cm2 at 1,5V and 850°C with 67,5% water in hydrogen electrode compartment. However, stability of the cells needs to be further investigated. With TOF-SIMS analysis it became apparent that Sr is moving through GDC intermediate layer and poorly conducting phases are formed in the GDC/10Sc1CeSZ boundary.

[1] C. Singhal, K. Kendall (Eds.), High-Temperature Solid Oxide Fuel Cells: Fundamentals, Design and Applications, Elsevier, Oxford, 2003.

[2]Bernadet, C. Moncasi, M. Torell, A. Tarancon, High-performing electrolyte-supported symmetrical solid oxide electrolysis cells operating under steamelectrolysis and co-electrolysis modes, Int. J. Hydrogen Energy 45 (2020)14208–14217

[3]Sanna, W. Zhang, P. Costamagna, P. HoltappelsSynthesis and electrochemical characterization of electrospun nanofiber cathodes for intermediate- temperature solid oxide fuel cells Int. J. Hydrog. Energy (2020), pp. 1-14
Improvement of Mechanical Strength and Long-Term Durability on Anode Support for Solid Oxide Fuel Cells by Adding Nanomaterials
Authors: Kwon Beom-Su , Song Rak-Hyun , Joh Dong Woo , Kim Tae-Hun , Hussain Amjad , Lee Seung-Bok , Lim Tak-Hyoung , Hong Jong Eun
Published: September 2023

Ni-8YSZ is widely used as an anode support for Solid Oxide Fuel Cells (SOFC). However, because of its low mechanical strength and high price, it is essential to develop an improved anode support material for commercialization. It has been reported that 3YSZ, which is used for bioceramics (implants) or refractory materials (for metallurgical metals), has more than twice as high mechanical strength as 8YSZ. In addition, since it is about 20 % cheaper than 8YSZ, it is under study as an anode support material. However, it has the disadvantage of significantly degrading the mechanical strength in the high-temperature humidified hydrogen atmosphere, which is the operating condition of the SOFC. In this study, we tried to improve this by adding nano-ZrO2 and nano-WO3. According to the Hall-Petch equation, it has been reported that the addition of nanoparticles has the effect of reducing the grain size and thus improving the mechanical strength. ZrO2 is the same material as the anode support and will not affect the material properties. According to the report, when WO3 is reduced that it will exhibit high mechanical strength in the form of a Ni-W alloy. For uniform dispersion, NiO and 3YSZ powders were ball-milled for 100 hours, and nano-ZrO2 and nano-WO3 were also added, respectively. At that same time, a binder and a pore former were added to secure the same porosity as the SOFC anode support. The mixed slurry was dried for 24 hours in the oven, then sieved, and pelletized. The powders were sintered at 1400 oC for 5 hours. Sintered samples were reduced at 750 oC in a hydrogen atmosphere for 8 hours. The reduced samples were heat treated in a reducing atmosphere (at 900 oC in a humidified hydrogen) for 500 and 1000 hours, respectively, which is an accelerated atmosphere. The three-point bending method was used to evaluate the mechanical strength and SEM microstructure analysis was conducted to analyze the cause of the improvement. As a result, the mechanical strength and long-term durability of the Ni-3YSZ anode support were greatly improved in the case of the sample with nano-ZrO2 added.
Monitoring Internal Oxygen Partial Pressure in YSZ Electrolyte Under Electrolysis Cell Mode Using 4-Electrode System
Authors: Kim Han Hwi , Lim Hyung-Tae
Published: September 2023

When solid oxide cells are operated in electrolysis mode, high oxygen pressures can be developed in electrolyte near the oxygen electrode/ electrolyte interface, leading to oxygen electrode delamination. Monitoring oxygen partial pressure in the electrolyte is necessary for the prevention of catastrophic failure in solid oxide electrolysis cells (SOECs). In this study, we applied four-electrode system to fuel electrode-supported SOECs. Four–electrode consists of air electrode, fuel electrode, Pt probe embedded in electrolyte and Pt reference electrode on the electrolyte edge. We measured internal electric potential near the oxygen electrode with respect to the reference electrode using embedded Pt probe. Based on this experimental setup, internal partial pressure of oxygen at the Pt probe location was determined. As tracing changes in internal oxygen partial pressure with varying overvoltage or current density, we investigated the relationship between operating conditions and the tendency of chemo-mechanical failure in solid oxide electrolysis cells.
Electrochemical Hydrogen Sulfide Decomposition Using Proton Conducting Ceramic for Pure Hydrogen Production
Authors: KIM Taehong , Lee Sanghun , Bae Minseok , Kim Junhyuk , Bae Joongmyeon , Katikaneni Sai P. , Lee Kunho
Published: September 2023

Hydrogen sulfide (H2S) is a substance that occurs during the process of processing sulfur, which is abundant in fossil fuels such as oil and natural gas, into high-quality fuel. Due to its high toxicity, it is classified as harmful industrial waste and removal in the process of discharging is essential. Until now, refiners have used the Claus process and the Wet Sulfuric Acid (WSA) process, which reacts hydrogen sulfide with oxygen to release it in the form of water or sulfuric acid. These processes require a huge amount of heat energy and only aim to remove hydrogen sulfide, so they emit hydrogen atoms contained in hydrogen sulfide in the form of water and sulfuric acid. Because hydrogen is an eco-friendly energy source that has recently been in the spotlight, hydrogen sulfide can be a valuable resource if hydrogen can be extracted from hydrogen sulfide. In this study, an electrochemical process that decomposes hydrogen sulfide and obtains hydrogen from hydrogen sulfide, replacing the conventional hydrogen sulfide removal process was proposed. To achieve this goal, thermodynamics of this reaction was analyzed and a solid oxide electrochemical cell based on proton conducting ceramic was fabricated for operating at high temperature and using perovskite structured electrodes. Experiments were then conducted to decompose hydrogen sulfide using fabricated cells and found that about 40 ppm, 100 sccm of hydrogen sulfide was decomposed at 600 oC by applying 0.5 V, 0.57 mA/cm2. Through this, the feasibility of the process was confirmed, and the durability test and regeneration process of the anode electrode were proceeded to solve degradation caused by sulfur deposits. In this study, a process has been proposed to effectively produce hydrogen of high value as an energy source, as well as to remove industrial waste hydrogen sulfide. It is expected that waste disposal and energy source production can be simultaneously produced in a clean and efficient way if cell performance improvement, removal of sulfur poison, and large systemization are applied to oil refiners' processes.
Electrochemical Performance and Mechanical Stress Evaluation of Metal-Supported Solid Oxide Fuel Cells Fabricated By Plasma Spray Method
Authors: Nishikawa Takeshi , Yashiro Keiji , Komaya Takumi , Kawada Tatsuya
Published: September 2023

At present, the most common type of SOFC is anode-supported SOFC (AS-SOFC), in which the cell is mechanically supported by the thick fuel electrode layer. Recently, Metal-supported SOFCs (MS-SOFCs) have attracted attention because of their potential for low cost and high mechanical robustness. However, the fabrication process of MS-SOFCs has not been established. The mechanical behavior of the cells under high temperature operation has not been clarified. In this study, we fabricated prototype MS-SOFCs using the plasma spray method. The cell was tested by electrochemical measurements, residual stress measurements, and SEM/EDX to clarify the mechanical behavior of MS-SOFCs under high temperature operation.

The layers of anode (NiO-YSZ), electrolyte (LSGM9182), and cathode (LSCF6428) were formed on a metal substrate (SUS430) by atmospheric pressure plasma spraying (APS) to fabricate a single cell of MS-SOFC.

Open circuit voltage, AC impedance, and I-V measurements were performed at 600°C, 650°C, and 700°C. The residual stress of LSGM9182 electrolyte was evaluated by cosα method [1] under the cell operation condition using specially designed chamber.

The MS-SOFC with thicker electrode layers showed the much lower OCV than that of theoretical. In addition, the electrolyte had vertical cracks between cathode and anode after the 2nd thermal cycle. However the MS-SOFC with thinner electrode layers showed the higher OCV, which was nearly theoretical value, and much better I-V characteristics than the cell with thicker electrodes. Electrochemical impedance measurement revealed the plasma sprayed electrodes showed acceptable performance even though its microstructure was not optimized. The residual stress of LSGM electrolyte in the cell did not change so much during the cell operation. This might be caused by existence of small cracks in the electrolyte layer.

This research was financially supported by NEDO.

[1] K.Tanaka, Journal of the Society of Materials Science,japan,vol.66,No.7 (2017) 479-487
Computational Investigation of the Potential SOFC Air Electrode YSr2Cu2FeO8-Δ
Authors: Gómez Toledo Marianela , Lopez Paz Sara , Garcia Martin Susana , Arroyo-de Dompablo Elena
Published: September 2023

YBaCuO-type oxides of the YSr2Cu2MO8-δ (M = Co, Fe) systems were previously studied as air electrodes for SOFCs1 and more recently have attracted great attention due to the electrocatalitic properties reported on YSr2Cu2FeO8-δ
2 and La1.5Ba1.5Cu3O7±
δ.3
The compound YSr2Cu2FeO7.56 is a p-type semiconductor, mixed valence Fe3+/Fe4+ and Cu2+/Cu3+ oxide, which exhibits an interesting electrochemical behavior associated to catalytic activity in the oxygen reduction reaction (ORR), being a potential air-electrode for solid oxide fuel cells (SOFCs)
2. In this contribution we present a computational study of the YSr2Cu2FeO8-δ (0< δ <1) system. We have firstly evaluated the performance of the generalized gradient approximation (GGA), the strongly constrained and appropriately normed (SCAN), and their Hubbard U corrections, GGA+U and SCAN+U, to reproduce the crystal and electronic crystal structures of YSr2Cu2FeO8-δ with δ = 0, 0.5 and 1. . The results validate the SCAN functional for the reliable investigation of these compounds. Further, the position of the oxygen electronic 2p band center is discussed as descriptor for the catalytic activity of these oxides.

J. E. H. Sansom, E. Kendrick, H. A. Rudge-Pickard, M. S. Islam, A. J. Wright and P. R. Slater, Journal of Materials Chemistry, 2005, 15, 2321-2327.

S. A. Lopez-Paz, R. Marin-Gamero, X. Martinez de Irujo-Labalde, J. Sanchez-Marcos, D. Perez-Coll, M. A. A. y. Franco and S. Garcia-Martin, Journal of Materials Chemistry A, 2021, 9, 8554-8560.

A. N. Keyun Li, K. Świerczek, A. Stępień, Y. Naumovich, J.Dąbrowa, M. Zajusz, K. Zheng, B. Dabrowski, Journal of Power Sources, 2022, 532, 231371.
Influence of A-site Deficiency and Ni/Co Ratio in B-site on Electrochemical Performance of (La0.25Sr0,25Ca0.45)yTi0.95Ni0.05-xCoxO3-
d
Anode
Authors: Kivi Indrek , Moeller Priit , Aruväli Jaan , Nurk Gunnar
Published: September 2023

La0.25Sr0.25Ca0.45TiO3
-d
(LSCT) is a perovskite (ABO3) type mixed ionic-electronic conductive (MIEC) oxide and has been proposed as an electrode material for high temperature fuel cell [1]. This material owing high conductivity, robustness in hydrocarbon fuels and significant amount of attention has been paid to improve the electrochemical activity [1, 2]. Doping of B-site with some d-metal cation (Ni, Co, Mn, V, Mo) has been demonstrated to improve the catalytic activity. One of the advantages of the MIEC conducting scaffold based electrodes is that the catalyst phase on the electrode surface can be kept to a minimum, usually less than 5 wt%, which minimizes any risks of physical damage during redox cycling [2].

In this work, Ni/Co ratio and deficiency of A-site, of (La0.25Sr0.25Ca0.45)xTi0.95Ni0.05-yCoyO3
-d
were varied. Electrical as well as electrochemical performance and chemical composition of LSCTNC surface was monitored. The electrochemical measurements of symmetric cells during 100 h tests show that small stochiometric changes in A-site significantly influence the activity and initial degradation rate of the electrode. The chemical and structural changes of the material surface have a key role on the electrochemical performance of the electrode [3].

The electrode materials were analysed using XRD, TOF SIMS and electrochemical methods. XRD and TOF SIMS results for studied electrode powders showed significant dependence of the lattice parameters and electrode surface composition on the perovskite elemental composition. The results from impedance spectroscopy (measured at temperatures from 973 to 1123 K in H2 environment, at OCV) demonstrate a significant influence of the A-site deficiency and B-site composition on the electrochemical properties of studied electrodes.

Robert Price, Mark Cassidy, Jan G. Grolig, Gino Longo, Ueli Weissen, Andreas Mai, John T. S. Irvine, Advanced Energy Materials, 11, 1 (2021).

Paul A. Connor, Xiangling Yue, Cristian D. Savaniu, Robert Price, Georgios Triantafyllou, Mark Cassidy, Gwilherm Kerherve, David J. Payne, Robert C. Maher, Lesley F. Cohen, Rumen I. Tomov, Bartek A. Glowacki, Ramachandran Vasant Kumar, John T. S. Irvine, Advanced Energy Materials, 8, 1 (2018).

Ove Korjus, Priit Möller, Kuno Kooser, Tanel Käämbre, Olga Volobujeva, Jaak Nerut, Sander Kotkas, Enn Lust, Gunnar Nurk, Journal of Power Sources, 494, 1 (2021).
Performance Prediction of Solid Oxide Fuel Cells Based on a Neutral Network Model
Authors: Fan Zhongcai , Zhang Ruiyu , Wang Yuqing , Wang Yabin
Published: September 2023

Predicting various parameters in a fast and accurate way plays an important role for the development of high-temperature sealed reactors such as the solid oxide fuel cells (SOFCs). However, the analysis of SOFC performance parameters mainly focuses on the development of multiphysics models, which is complicated and slow, causing inefficiency in the prediction of key parameters. In our study, a neural network prediction model of SOFCs was developed in combination with the deep learning method. The neural network model was trained by using the results from a multiphysics model validated by experiments. The trained SOFC neural network model was found to have good consistency with the simulation results of multiphysics model. The neural network model was further utilized in a system-level model to provide fast and accurate prediction of the system performance.

Keywords: SOFC, Multiphysics model, Neural network model, System simulation
Enhancing Low-Temperature SOFC Performance and Durability via Surface Modification
Authors: Wachsman Eric , Robinson Ian , Huang Yilin , Horlick Samuel Aaron , Hussain A. Mohammed , Pesaran Alireza
Published: September 2023

The development of active cathodes is one of the most critical challenges to lowering the operating temperature for solid oxide fuel cells (SOFCs). Here we demonstrated that by modifying the cathode surface chemistry at a relatively low temperature, the cathode activity and durability can be simultaneously enhanced. This low-temperature modification using multi-valent cations activates the highly defected surface and maintains the nanoscale electrocatalysts by bypassing the high-temperature sintering procedure for SOFC fabrication. The modified cathode at 600 °C shows an order of magnitude reduction in impedance to only 0.05 Ωcm2 with a peak power density of 1.1 W/cm2 and is stable over 2000 hours. The combination of in situ characterization, distribution of relaxation time analysis on impedance spectroscopy, and surface chemistry analysis reveals the importance of surface chemistry control on the gas-solid reaction activity and durability and provides the design principle for numerous future solid oxide cells.