bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of Misfit-Layered Cathode Materials for Improving Electrocatalyic Activity in Reversible Protonic Ceramic Cells
Authors: Park KwangHo , Park Gwang-Min , Park Jun-Young
Published: May 2023

In reversible protonic ceramic cells (RPCCs), due to their fast oxygen reaction kinetics, perovskite-structured cathode materials have been in the spotlight up to this point. However, such materials have some drawbacks such as low phase stability in humid atmospheres, high thermal expansion coefficient, and relatively low proton conductivity despite high electrocatalytic activities when used as steam-air electrodes. Hence, we suggest that novel misfit-layered structure Ca3Co4O9+δ (CCO)-based materials be used to overcome these technical issues with superior performance in RPCCs. Although CCO is a cobaltite-material, CCO has a similar thermal expansion coefficient as BZCYYb electrolyte’s (10‒12×10-6 K-1). Moreover, the plate-like morphology of the CCO-based materials are favorable for the introduction or emission of steam. Further, with alkali metal doping in Ca-site, CCO generates extra charge carrier species with the modified Co oxidation state, which results in high proton uptake and diffusion mechanism. Altogether, 5 mol% potassium-doped CCO-cells show great potential as a cathode material.
Fabrication and Characterization of Freeze-Cast Tubular Solid Oxide Cells
Authors: Du Yanhai , Woodson Theo , Panthi Dhruba
Published: May 2023

Increasing triple phase boundaries (TPBs) and reducing gas diffusion limitation in electrodes of solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) have always been a goal for highly desirable electrochemical performance. Freeze-casting (also called ice-templating) is a promising method to produce hierarchically arranged porous ceramics with aligned and directional pores that could assist to reach such a goal. After reviewing the previous work on ceramic freeze-casting, we focused on optimizing the processes to better engineer tubular supports for SOFC as well as SOEC applications. Although the optimized process does not have too many constraints on the types of ceramic materials (except particle size and surface area), we selected the commonly used 8 mol.% yttria stabilized zirconia (8YSZ)/NiO composite material set as a starting point. Cast slurry formulations, cast temperatures, slurry feeding methods and freeze-drying conditions were studied. Microstructures of the tubular parts prepared at various conditions were examined. Finally, as an example for SOFC application, the fuel cell performance is reported.
Validation of and Simulations using a High-Temperature Electrolysis Model
Authors: Nohl Markus , Vinke Izaak C. , Eichel Rudiger-A , de Haart L.G.J. (Bert)
Published: May 2023

A continuum mechanistic, real-scale model with the most important reactions of high-temperature electrolysis is proposed. IV-characteristics and impedance spectra serve as comparison to experimental data for steam, CO2 and co-electrolysis. The exchange current-density i0 can be determined to the same order of magnitude as observed in experiments for steam electrolysis. The IV-characteristics for CO2 electrolysis are well described by an i0 one order of magnitude lower as compared to steam electrolysis. Parameter variations identify contributing variables determining the shapes of characteristics. Limitations in prediction are revealed for low current densities up to 0.5 A∙cm-2. EIS calculations demonstrate the dominant behavior of charge transfer or oxygen ion incorporation into the lattice as function of i0 or temperature. The model forms a solid basis for various future investigations like a more detailed reaction system with possible intermediates or degradation and poisoning effects.
An Analysis of Capacitive Contributions of the Cell Impedance during High-Temperature CO2 and Co-Electrolysis
Authors: Dittrich Lucy , Vinke Izaak C. , Eichel Rudiger-A , de Haart L.G.J. (Bert)
Published: May 2023

The electrolysis of steam (H2O) and/or carbon dioxide (CO2) is a sustainable way to produce hydrogen (H2) and/or carbon monoxide (CO). In research and development the processes occurring at the electrodes in the electrolysis cells are usually analyzed by electrochemical impedance spectroscopy (EIS). The spectra are evaluated by equivalent circuit models (ECMs) consisting of resistances, capacitances and/or inductances. For the further assignment of the processes, the spectra are measured at varied operating conditions. However, in many cases only the dependencies of the resistances resulting from the ECM are discussed in detail. In this publication, we examined the capacitive contributions to the impedance of the electrolysis of H2O and CO2 and their dependencies on operating conditions. In comparison, the capacitances of CO2 and co-electrolysis only differ in the low frequency range, which could describe an adsorption process additional to the reported gas diffusion impedance.
Bilayer Cell Model and System Design of Highly Efficient Protonic Ceramic Fuel Cells
Authors: Otomo Junichiro , Yamate Shun , Ortiz-Corrales Julián Andrés
Published: May 2023

A highly efficient power generation system was designed by minimizing leakage current in protonic ceramic fuel cells (PCFCs) using bilayer electrolytes. The best electrolyte designs are achieved by optimizing the cell efficiency based on the transport properties of electrolyte materials assuming hydrogen as fuel. In parallel, the effect of the electrodes on the overall cell performance was also considered. Additionally, a PCFC system was modeled using the designed cells. Two PCFC systems were investigated. One based on hydrogen as a fuel, and another based on methane as fuel. It was found that a bilayer electrolyte consisting of BaZr0.8Y0.2O3−δ (BZY) with a thin layer of lanthanum tungstate (La28-xW4+xO54+3x/2v2-3x/2) is the most effective at reducing leakage current at 600°C. For this cell, a system efficiency of 69% (LHV, DC) and 65% (LHV, AC) were obtained under the cell voltage of 0.93 V, with a leakage current ratio of less than 1%, and fuel utilization of 95% when using hydrogen as fuel. On the other hand, when methane was used as fuel, the efficiency increased up to 78% (LHV, DC) and 74% (LHV, AC).
Exploring Solid Oxide Electrolysis Cell Design for an Optimal Flow Distribution and Thermal Management
Authors: Jimenez-Martín Gonzalo , Judez Xabier , Aguado Mónica , Garbayo Iñigo
Published: May 2023

Green hydrogen is widely considered as a reliable solution to provide flexibility to a renewable energy-based system, decarbonize hard-to-abate-sectors and achieve a net zero emissions scenario. In this sense, Solid Oxide Electrolyzers (SOE) are meant to play an important role for the production of green hydrogen. In order to fulfill high performance and durability requirements, SOE stack design needs to be carefully contemplated. For that purpose, the design of the interconnect plates is evaluated in this work. Simulations conclude that interconnector plate manifold is the most influential cell feature in terms of flow distribution and therefore, a simple modification in the number of inlets and outlets can improve flow distribution, conducting to normalized mass flows near to the unit and low pressure drop. Finally, by adjusting interconnect plate internal design, flow distribution is further improved and thermal gradients are reduced below the desirable limit of 10 K·cm-1.
Oxygen Non-Stoichiometry and Point Defect Equilibria in (La1/6Pr1/6Nd1/6Gd1/6Ba1/6Sr1/6)MnO3-
δ
Authors: Bishop Sean R , Zhang Dawei , Liu Cijie , Li Wei , Salinas Perla A , Smith Andrew I , Coker Eric N , De Santiago Héctor A , Liu Xingbo , McDaniel Anthony H , Luo Jian
Published: May 2023

In this work, the A-site of the common SOFC cathode La0.8Sr0.2MnO3-δ (LSM) is modified with additional lanthanide and alkali elements, resulting in the composition (La1/6Pr1/6Nd1/6Gd1/6Ba1/6Sr1/6)MnO3-
δ. We show that the amount of oxygen released during reduction measured by thermo-gravimetric analysis is significantly greater for this “high entropy” perovskite oxide (HEPO) in comparison with La2/3Sr1/3MnO3-δ, the latter having the same amount of total acceptor dopant and with a similar average A-site radius. The origins of enhanced reduction will be discussed.
Investigation on Reaction Mechanism in an SOFC Composite Cathode by Using Patterned Thin Film Electrodes
Authors: Diao Zhuo , Imaizumi Takaaki , Mizuno Keita , Kimura Yuta , Nakamura Takashi , Yashiro Keiji , Iguchi Fumitada , Kawada Tatsuya , Amezawa Koji
Published: May 2023

The reaction mechanism in an SOFC composite cathode was investigated by using patterned thin film model electrodes. In this work, we proposed new types of model electrodes, which could reproduce SOFCs cathodic reactions in a composite electrode of a mixed conducting electrode and an electrolyte. Then the model electrode was fabricated by choosing La0.6Sr0.4CoO3-δ
(LSC) and Ce0.9Gd0.1O1.95 (GDC) as the electrode and the electrolyte, respectively. From the DC polarization measurements of the model electrode, it was found that making a composite of LSC and GDC can improve the cathodic performance especially at lower temperatures, possibly due to higher oxide ion conduction in GDC than LSC.
Current Leakage and Faradaic Efficiency Simulation of Proton-Conducting Solid Oxide Electrolysis Cells
Authors: Jin Xinfang , Shoukry Yasser
Published: May 2023

In this study, we simulated BZY electrolyte-supported proton-conducting solid oxide cell by coupling surface defect chemistry reaction with charged species transport. We validated the model parameters by concentration as a function of temperature, conductivity under dry and wet oxygen as a function of oxygen partial pressure and temperature. The results indicate that the high electron-hole mobility (diffusivity) is mainly responsible for the high leaking current under high temperatures. The Faradaic efficiency stays low or even negative under low operating voltage or high temperature and plateaus as the cell voltage increases. The model developed in this study is a useful tool to understand the leaking current in BZY electrolyte and provide design strategies to avoid/mitigate such significant inefficiency for water electrolysis operation.
Short Term Silver Electrode Microstructure Changes Under Epoxidation Conditions for Solid Oxide Electrolysis Cells
Authors: Jenkins Cody , Tian Jiashen , Milcarek Ryan J
Published: May 2023

Ethylene epoxidation is an important reaction to form ethylene oxide (EO), which is a precursor to many other critical chemicals. This study links short-term EO production to the effects on the microstructure of Ag/yttria-stabilized zirconia cells with and without an electrochemically promoted catalyst (EPOC). Nano scale features called striations were observed using a Scanning Electron Microscope (SEM) on the silver under all reaction conditions tested. While appearing in both cases, the striations for the EPOC case are finer in size (~150 to 250 nm) compared to the no current case (~400 to 500 nm). These features did not appear when epoxidation conditions were not present. Striation formation was further linked to the epoxidation reaction through electrochemical impedance spectroscopy (EIS) and gas chromatography (GC). Ethylene conversion to EO declines over the course of hours as striations form, indicating that striations have a negative influence on the reaction. Striation formation further effected the electrochemical performance of the cells, resulting in the low frequency depressions observed in EIS to shrink in both cases after 10 hours of epoxidation.
Optimizing the Copper Content in GdBa0.5Sr0.5Co2-XCuxO5+δ Double Perovskites as the High Performance Oxygen Electrodes for Reversible Solid Oxide Cells
Authors: Li Keyun , Świerczek Konrad , Winiarz Piotr , Brzoza-Kos Agnieszka , Stępień Anna , Zhang Yang , Zheng Kun , Cichy Kacper , Niemczyk Anna , Naumovich Yevgeniy
Published: May 2023

Doping with copper is studied in a series of double perovskite-type GdBa0.5Sr0.5Co2-xCuxO5+δ, candidate oxygen electrode materials for reversible Solid Oxide Cells. Obtained by a sol-gel method, the material with x = 1.15, having the highest amount of the introduced Cu (lowest Co content) is selected, and systematically evaluated regarding physicochemical characteristics, as well as chemical stability with La0.8Sr0.2Ga0.8Mg0.2O3-δ and Ce0.9Gd0.1O2-δ solid electrolytes. Promising electrochemical performance is obtained if this compound is used to manufacture oxygen electrodes, with the recorded low polarization resistance of 0.144 Ω cm2 at 700 °C, and 0.020 Ω cm2 at 850 °C. Also, the anode-supported laboratory cell is found to deliver over 725 mW cm-2 power density at 850 °C, and shows good performance in the electrolyzer mode.
Recovery and Delay of Impurity-Induced Poisoning of Oxygen Exchange Kinetics in Mixed Conducting Oxides Via Controlled Surface Acidity
Authors: Seo Han Gil , Tuller Harry L.
Published: May 2023

The oxygen exchange kinetics in mixed conducting oxide surfaces are critical to a variety of energy-related technologies, including solid oxide fuel/electrolyzer cells (SOFCs/SOECs), permeation membranes, batteries, and sensors. Such devices, however, commonly suffer from performance degradation from impurity-poisoning during long-term operation. In our previous findings, it was found that while acidic additives can depress the surface exchange kinetics, basic additives can enhance these kinetics. Inspired by these findings, we demonstrated the ability to regenerate acidic (Cr and Si)-poisoned surfaces by compensating with basic additive infiltrants (Li and Ca). Electrical conductivity relaxation measurements on porous mixed conducting oxide specimens were used to examine the impact of infiltrants on the oxygen exchange rate coefficient (kchem
) and revealed that the recovery of poisoned surface kinetics can be attributed to the compensation of depleted surface electrons by basic additives.
The Impact of Sintering Conditions on the Inner Microstructure of Composites: LSM:YSZ Electrode Case Study
Authors: Carda Michal , Budac Daniel , Paidar Martin , Bouzek Karel
Published: May 2023

The sintering of composite materials can pose a significant challenge if the composite constituents display substantially different melting points and if an intricate inner microstructure is required to be formed by the process. One of such materials represents a LSM:YSZ composite, utilized as an oxygen electrode in the solid oxide cells, where a compromise between particle interconnection and mass transport is essential. Thus, a well-understood development of microstructure during the sintering process is crucial to address these contradictory requirements. LSM:YSZ samples in a form of self-supporting bars and thin layers deposited onto YSZ support were investigated to demonstrate the impact of sintering temperature and the mixture composition on the resulting inner microstructure. Results obtained by means of SEM analysis allow to understand the connection between properties of powder materials precursors and the microstructure of densified bodies with respect to the sintering parameters.
A Comparative Study of the Performance and Electrode Processes of Solid Oxide H2O Electrolysis and CO2 Electrolysis
Authors: Liang Jingjing , Han Minfang , Ni Meng
Published: May 2023

Solid oxide CO2 electrolysis was less studied compared with H2O electrolysis and the relevant reaction mechanism and electrode processes were poorly understood. This paper investigated the performance and electrode processes differences between CO2 electrolysis and H2O electrolysis. The shape of j-V curves, electrochemical impedance spectroscopy data and calculated distribution relaxation time results were analyzed. It was found that the performance of CO2 electrolysis degraded the most compared with that in SOFC mode and for H2O electrolysis after a 65 h’ operation. Meanwhile, j-V curve of CO2 electrolysis changed a lot and finally showed a convex total resistance pattern with applied current. It was also found that the characteristic frequency of charge transfer reaction and diffusion process for CO2 electrolysis was much lower than that of H2O electrolysis. A thermal activated peak at 10-100 Hz which was not noted for H2O electrolysis was considered to be CO2 adsorption and dissociation process in fuel electrode. Besides, diffusion process for H2O-H2 and CO2-CO mixture also differed. Finally, it was indicated that the different performance degradation may be due to different suppressed degree of charge transfer reaction in fuel electrode for H2O electrolysis and CO2 electrolysis and additional suppressed adsorption or dissociation process of CO2 for CO2 electrolysis.
Redox Tolerant Solid Oxide Electrolysis Cathode for CO2 and Steam
Authors: Hafen Tyler , Rane Taylor , Larsen Dennis , Pike Jenna , Hartvigsen Joseph , Elwell Jessica , Coyle Christopher , Marina Olga A , Elangovan S
Published: May 2023

The OxEon team led the development of solid oxide electrolysis cell(SOEC) stacks to convert atmospheric CO2 to pure O2 for the Mars Perseverance Rover mission. The cathode material set was not redox tolerant, therefore a recycle loop was implemented to include reducing CO gas in the stack feed. Since then, OxEon has investigated a combination of materials and engineering solutions to improve redox tolerance of the cathode materials so that 100% dryCO2 (or steam without H2) could be fed directly into a stack without harm. The developed set of cathode materials exhibit remarkable robustness through extreme redox cycling and thermal cycling, as well as higher coking tolerance from preliminary testing. This enables simpler operation (no recycle) and prevents damage from unintended system changes, providing a new solution to operational challenges in SOEC systems. Steam redox tolerance was independently verified from collaboration with Pacific Northwest National Laboratory (PNNL).
Electrochemical Performance and Durability of a Solid Oxide Cell with Nanoparticles-Modified Electrodes for CO2 Electrolysis
Authors: Yu Miao , Tong Xiaofeng , Brodersen Karen , Chen Ming
Published: May 2023

Solid oxide electrolysis cell (SOEC) is one of the most effective technologies for converting carbon dioxide to carbon monoxide using renewable energy sources. This work investigated the electrochemical performance and long-term durability of a Ni/yttria-stabilized zirconia (YSZ)-supported planar-type SOEC cell (CGO@Ni/YSZ|YSZ|CGO|LSC/CGPO@CGO) infiltrated with nano-catalysts for CO2 electrolysis. The Ni/YSZ fuel electrode was infiltrated with Ce0.8Gd0.2O2−δ (CGO) solution, and the porous CGO scaffold was co-infiltrated with La0.6Sr0.4CoO3-δ (LSC) and Gd, Pr co-doped CeO2 (CGPO) nano-sized electrocatalysts. The cells were operated at 800 °C and -1 A/cm2 for 1548 h with a mixture of 24 L/h CO2/CO (83/17) supplied to the fuel electrode and pure O2 to the oxygen electrode. Electrochemical impedance spectroscopy (EIS) and distribution of relaxation time (DRT) analysis were conducted. During the entire durability testing period, the cell voltage increased from 1246 mV to 1400 mV with a degradation rate of 99.1 mV/kh (7.95%/kh). Following the recovery after an unexpected power outage, the cell demonstrated an activation process over ⁓110 h, with a voltage decrease from 1337 mV to 1263.9 mV. Furthermore, the cell showed a much lower degradation of ohmic resistance R
s (7.14 mΩ cm2/kh) compared to that of polarization resistance R
p (129.05 mΩ cm2/kh). DRT reveals that the degradation originates from both electrodes. The present study reveals that it is crucial to carefully select the appropriate electrocatalyst candidate considering the specific operating conditions.
Analysis of the Long-Term Operation of an Electrolyte-supported Solid Oxide Cell Under Co-electrolysis Regime
Authors: Lopez de Moragas Albert , Tsai Chen-Yu , Hauch Anne , Chen Ming
Published: May 2023

The solid oxide cell technology allows to produce synthesis gas (CO+H2), a precursor for e-fuels and other chemicals. This work reports on the long-term performance of an electrolyte supported cell (Ni-CGO/3YSZ/LSCF-CGO), operated at industrially relevant co-electrolysis conditions (32.5 % H2, 35 % H2O, 8.1 % CO, 24.4 % CO2, -0.5 A/cm2, 815 °C). The cell had a Ni-CGO fuel electrode (~30 μm thick), a 3YSZ electrolyte (~90 μm) and an LSCF-CGO oxygen electrode (~35 μm thick) plus a thin CGO barrier layer in-between. The cell was operated for 2300 h at constant galvanostatic conditions, with an overall degradation of 80 mΩcm2/kh. At the start of the test, the ohmic resistance contributes to almost 90 % of the ASR (area-specific resistance), but the increase in Rp (polarization resistance) is what contributes the most to the increase in total cell ASR during the long-term operation. This increase in ASR is not constant over the entire test time. On the contrary, it is considerably higher during the first 300 hours (180 mΩcm2/kh) and then it levels off and stabilizes to 32 mΩcm2/kh during the remaining approx. 2 kh of the long-term operation. The measured electrochemical impedance spectra showed a decrease in the performance of the Ni-CGO fuel electrode. A possible explanation for the observed fuel electrode degradation was found via SEM-EDS, where a considerable quantity of silicon-containing compounds was found in the active area of the Ni-CGO fuel electrode.
Engineered Nanofunctional Thin Films as Interfacial Layers to Enhance Performance and Durability of SOFCs
Authors: Machado Marina , Baiutti Federico , Bernadet Lucile , Morata Alex , Nuñez Marc , Ouweltjes Jan Pieter , Fonseca Fabio Coral , Torrell Marc , Tarancón Albert
Published: May 2023

A strategy to improve the performance and durability of solid oxide fuel cells (SOFCs) is to increase the cathodic activity and decrease the interfacial resistance between the cathode and electrolyte. Pulsed laser deposition (PLD) has been shown to be a promising method to engineer functional interlayers to enhance the cell's performance. In the present study, a bilayer consisting of Sm0.2Ce0.8O2−δ (SDC) barrier layer (BL) and a nanocomposite consisting of SDC-La0.8Sr0.2MnO3−δ (SDC-LSM) employed as a cathode functional layer were deposited by PLD in an anode supported SOFC. The fuel cell showed a maximum power density of 0.30 W∙cm−2 at 750 °C. Most importantly, a durability test carried out for 700 h at 750 °C showed a remarkably stable performance of the fuel cell.
Shape-Controlled Ni Supported GDC Catalyst and its Application in Direct Ethanol Solid Oxide Fuel Cells
Authors: Machado Marina , Rodrigues Lays Nunes , Vilela Vanessa Bezerra , Ferlauto Andre Santarosa , Moraes Tamara , Fonseca Fabio Coral
Published: May 2023

Matching catalytic activity with the high temperature heat treatments required to process solid oxide fuel cells (SOFCs) can be a challenge. Shape control is an interesting strategy to stabilize the surface of nanoparticles during heat treatments. In this study, nickel-based catalysts supported on shape-controlled (nanorods and nanocubes) gadolinium-doped cerium oxide (GDC) were evaluated for direct ethanol SOFCs. The morphology of the support had a significant effect on the catalytic activity. It was shown that the Ni catalyst supported on the GDC nanorods maintained high catalytic activity after heat treatments for catalytic layer sintering. Such catalyst was applied as a catalytic layer on a SOFC operating directly on anhydrous ethanol at 700 °C. The fuel cell operated for more than 100 h under 0.6 V displaying consistent performance with no indication of degradation from carbon deposition.
Development of Protonic Ceramic Fuel Cell Using BaZr0.2Yb0.8O3-δ as the Electrolyte
Authors: Kuroha Tomohiro , Yamauchi Kosuke , Mikami Yuichi , Okuyama Yuji
Published: May 2023

Improving the activity of the cathode is important for the practical use of Protonic Ceramic Fuel Cells (PCFCs). We developed BaZr0.375Yb0.125Co0.500O3-δ as a new cathode material for the PCFCs using BaZr0.8Yb0.2O3-δ as the electrolyte. Anode supported cells using these materials were fabricated and the electrochemical performances were investigated. The maximum power density was 0.60 W/cm2 at 600°C. The voltage degradation rate over 1000 hours in the durability test under the constant current mode was 7.3%/kh. After 1000 hours of durability test, diffused Ni and Co were unevenly distributed in the electrolyte of the cell. Therefore, prevention of diffusion of electrode-derived elements such as Ni and Co is considered to be one solution to improve durability.
Evaluation of Electrolytic Characteristics with a Single Cell Developed as SOFC
Authors: Imabayashi Takumi , Asano Koichi , Mugikura Yoshihiro
Published: May 2023

The reversible solid oxide cell (rSOC) can operate both SOFC and SOEC modes reversibly. It is necessary for developing the rSOC to clear the reversible operation problems by evaluating cell performance of SOFC and SOEC modes. Based on our original performance evaluation method of SOFC which was previously developed, a new performance evaluation method of SOEC which can be adapted under various temperature conditions has been developed in this report. The cell, which was developed as SOFC, performance before and after the CO2 direct electrolysis test (CO2+2e-→CO+O2-) was compared by using the performance evaluation methods of SOEC and SOFC. As a result, the IR loss and the cathode overvoltage increased after the CO2 direct electrolysis test in both SOEC and SOFC modes.
Durability Study of Anode-Supported SOFC with Large-Area Fabricated By 4-Layer Sequential Co-Lamination and GDC Co-Firing Process
Authors: Hussain Amjad , Song Rak-Hyun , KIM Taehun , Mehdi Ali Muqaddas , Shin Ji-weon , Kwon Beom-Su , Ali Muhammad Measam , Joh Dong Woo , Khan Muhammad Zubair , Hong Jong-Eun , Lee Seungbok , Lim Tak-Hyoung
Published: May 2023

Electrolyte-Cathode interfaces are life-threatening regions of solid oxide fuel cells where degradation phenomena occur due to chemical interdiffusion. The Buffer layer is inserted between the electrolyte-cathode to limit the cation exchange across the interface. However, state of the art buffer layer coated by screen printing does not fully prevent cation migration which results in the formation of insulating phases such as La2ZrO7 and SrZrO3. Herein, a reliable four-layered (NiO-YSZ, NiO-CeScSZ, CeScSZ, and GDC) thin film-based anode-supported SOFCs with a large-area (12 cm × 12 cm) were fabricated by sequential co-lamination, in which all cell components perform a distinct role to enhance the interfacial connectivity and packing density of electrolytes. This enhanced connectivity with a highly dense electrolyte (5-6 µm) and buffer layer (2-3 µm) was accomplished on the porous anode support without any structural defects. The single cell (144 cm2) showed a power output of 38 W at a total current of 50 A (700 °C). The Post-tested cell had exceptional micro-structural characteristics and excellent interfacial adhesion and retained its structural integrity during steady and unsteady state operation. Also, the formation of insulating phases and decomposition of the cathode were completely prevented, resulting in a remarkable improvement in durability. The cell with a four-layered structure exhibits an extreme low degradation rate of 0.2% kh-1 under 25 A current and 21 dynamic load cycling conditions, which satisfies the strict benchmark of durability for technology commercialization.
The Reduction Step and Mechanism Analysis of the NiO-8YSZ Anode Affected by the Hydrogen Concentration
Authors: Wang Xiaoyu , Zhang Haiming , Song Wenwan , Han Minfang
Published: May 2023

Hydrogen of different concentrations humidified by the water vapour were used to reduce the NiO-8YSZ anodes of the solid oxide fuel cells (SOFCs) at 700℃ and 720℃. The experimental results suggested that four periods of the open circuit voltage, namely rapid increase period, temporary stasis period, slow increase period and final stable period exist successively during the reduction, the characteristics of which were closely related to the hydrogen concentration of the reduction. After the reduction, the polarization resistance on open circuit and on load showed different correlation with the hydrogen concentration of the reduction. The variation trend of the initial performances of the SOFCs corresponded highly to the polarization resistance on load. The shrinking core model of the reduction of the NiO suggested that the further reduction of the unreacted NiO core would most likely cause the activation of the SOFC.
A Comprehensive Investigation on the Direct-Ammonia Thin-Film Solid Oxide Fuel Cells (TF-SOFCs) and the Effect of Porosity-Control of the Anode Support Layer
Authors: Oh Seongkook , Lee Jong-Ho , Yoon Kyung Joong , Ji Ho-il , Son Ji-Won , Yang Sungeun
Published: May 2023

Ammonia is highly regarded as a hydrogen storage and transportation medium due to its various advantages. Solid oxide fuel cells (SOFCs) can achieve high synergy by using ammonia directly as fuel without the ammonia decomposition reactor and filtration devices. We confirmed the distribution of hydrogen produced by the decomposition of ammonia through 2D multi-physics numerical modeling and predicted the decomposition rate and maximum current density according to the tortuosity. Based on the results, we adjusted the pore volume of the anode-support layer using PMMA to reduce tortuosity and facilitate hydrogen supply and produced anode support layer-anode functional layer substrate. We then manufactured a Thin-film SOFC and tested using hydrogen and ammonia fuel, and achieved high performance of 1897 and 1357 mW/cm2 at 650 °C.
Improvement of the SOFC System by Anode Recirculation
Authors: Liu Yaodong , Han Minfang , Sun Kaihua , Li Qingxun
Published: May 2023

Solid Oxide Fuel Cells (SOFCs) provides an efficient and clean pathway to generate electricity. In this study, two system configurations with anode off-gas recirculation are introduced, and corresponding process models are developed using MATLAB. The study examines the effects of two key parameters, namely system methane utilization and recirculation ratio, on system characteristics, based on the typical performance of a 30-cell stack. Suitable operating parameter ranges are selected for both system configurations, and their respective characteristics are compared. The results demonstrate that D#1 system configuration improves system fuel utilization from 76.6% to 83.0% without altering the operating conditions of the stack. D#2 system configuration achieves a fuel utilization of 88.6%. The results indicate the potential for further enhancing the electrical efficiency while maintaining the output power and operation stability. This study provides valuable insights for the design and parameter selection of practical systems in future research.
Investigation of Surface Oxide Layer Structure to Improve Durability of Stainless Steels Under Humidified Hydrogen
Authors: Taniguchi Shunsuke , Inoue Yuko , Uryu Chie , Pham Hung Cuong , Chou Jyh-Tyng , Sasaki Kazunari
Published: May 2023

Durability of low cost stainless steels, selected from the materials widely used in other applications, was investigated under humidified hydrogen of SOFC anode condition. JIS SUS430J1L exhibited higher resistance for water oxidation. The feature came mainly from the thin Cr-rich oxide layer covering the alloy uniformly with little defects or segregations. Under humidified H2 at 700oC, Mn migrated outward and the morphology changed. Durability of the alloy seems to depend on the inner side of the surface oxide layer. Although the Cr-rich oxide layer blocked outward diffusion of metal ions, the layer could not block inward diffusion of oxygen ion completely. Improvement of the durability is possible by controlling the thickness of the surface oxide layer by the pre-heat-treatment.
Layout and Experimental Results of an 10/40 Kw rSOC Demonstration System
Authors: Peters Roland , Kruse Nicolas , Tiedemann Wilfried , Hoven Ingo , Deja Robert , Schäfer Dominik , Kunz Felix , Eichel Rudiger-A
Published: May 2023

Forschungszentrum Jülich has been operating an rSOC system in the 10/40 kWAC power class since 2021. This system uses four 20-layer sub-stacks in the mark H20 stack design. During the test campaign, a power range from 1.7 to 13 kWAC could be shown in fuel cell mode. The highest efficiency in fuel cell mode of 63.3 % was achieved at a power output of 10.4 kWAC, related to the lower heating value (LHV) of hydrogen. With a power input of -49.6 kWAC, the highest efficiency of 71.1% (LHV) was achieved in electrolysis mode. At this point, 11.7 Nm³ h-1 of hydrogen were produced. The following manuscript shows the layout and the experimental results of the rSOC demonstration system.
Investigation of the Electrode-Electrolyte Interfaces in Solid Oxide Cells
Authors: Lenser Christian , Schwiers Alexander , Ramler Denise , Menzler Norbert H.
Published: May 2023

The interface between electrodes and electrolyte in a solid oxide cell (SOC) are critical locations for cell performance. These interfaces originate from the chemical interaction of two different materials during processing. Different mechanisms can degrade cell performance on the air and fuel side, which necessitates different approaches to mitigate these effects. Here, materials interaction during processing is discussed for selected materials on the air side of an SOC. A new approach to obtain barrier layers of doped ceria with submicron thickness is introduced, and it is confirmed that only the interdiffusion layer between ceria and zirconia is necessary to prevent the formation of SrZrO3. Furthermore, the effect of the microstructure of a GDC layer on the sintering of a perovskite air electrode in this layer is investigated. It is demonstrated that the morphology of the GDC layer has an impact on the quality of the interface between air electrode and barrier layer.
Experimental Demonstration of the Electric Efficiency with BZYb based Protonic Ceramic Fuel Cell
Authors: Yamauchi Kosuke , Mikami Yuichi , Kuroha Tomohiro
Published: May 2023

Protonic Ceramic Fuel Cell (PCFC) is expected to be the next-generation fuel cell due to its higher energy conversion efficiency. We evaluated the electric efficiency using a Φ60mm anode supported BZYb cell and a newly designed jig. The Φ60mm BZYb cell performed almost as well as the Φ20mm cell, and the maximum power reached 7 W at 12.9 A at 600ºC. In addition, we obtained the cell performance of 0.3 A cm–2 current density under various Uf (fuel utilization) condition. We demonstrated that a BZYb based PCFC could be operated at a high Uf condition (i.e., Uf = 90%), and the maximum electric efficiency was 55% (DC).
High Entropy Perovskite Electrolytes for Reversible Protonic Ceramic Electrochemical Cells
Authors: Oh Seeun , Kim Dongyeon , Lee Kang Taek
Published: May 2023

Reversible protonic ceramic electrochemical cells (R-PCECs) have become the cornerstone of low-temperature solid oxide electrochemical cells (SOCs) below 600 °C. Low activation energy and high energy conversion efficiency are primary significance of R-PCECs. However, electrolytes of high-performance R-PCECs still suffer from poor tolerance to complex operating conditions. To overcome their low stability and enhance proton conductivity, various cations have been doped into the Ba-based perovskite oxide electrolyte. Developing high entropy oxides by introducing multiple metal cations into A- or B- sites of the perovskite structure can be an effective solution for the structural stability. Due to the effect of the entropy-dominated stabilization in multi-doped perovskite oxides, the material can remain single phase under extreme temperatures and chemical environments. Promising high entropy stabilization concepts were adapted to electrolytes, and finally, durable proton-conducting perovskite oxide was designed. Here, we will present our recent progress on development of high entropy perovskite oxide electrolytes for R-PCECs.
Development of Long Duration Button Cell Test Stands and Testing Protocols
Authors: Hartvigsen Jeremy , Kane Nicholas , Casteel Micah , Gomez Joshua , Priest Cameron , Wang Lucun , White Casey , Boardman Richard , Ding Dong
Published: May 2023

Increasing the longevity of SOEC systems is a key impact for hydrogen production. Improving stack lifetime from 20,000 to 60,0000 hours results in a cost reduction of $.20 on the levelized cost of hydrogen. Long duration test stand development for button cells is a growing need to establish Accelerated Stress Testing, and long-duration testing benchmarks. Improving the reliability of test stands and long-term cell testing enables deeper investigations into long-term degradation behavior. Significant deviations between cell degradation mechanisms during the initial 500 hours of operation and the mechanisms after 500 hours exist. Establishing the mechanisms of long-duration degradation as opposed to initial break-in stability is necessary in order to achieve reliable systems that can operate for upwards of 80,000 hours.
High-Entropy Proton Conductive Electrolyte for Intermediate Temperature Operation
Authors: Lo Faro Massimiliano , Vecino-Mantilla Sebastian
Published: May 2023

Due to the high operating temperatures required by commercially available cells, solid oxide electrochemical devices are currently limited in their application to sectors ranging from production to storage of energy, from pollution abatement to pure oxygen distillation. In this study, it is presented a novel electrolyte that promises to dramatically reduce the operating temperature of solid oxide electrochemical devices. Our proposed electrolyte consists of four cations and non-critical raw materials with a stoichiometry that allows for maximum entropy in an ABO3-based oxide. Preliminary results presented in this proceeding indicate that the material outperforms commercial cerates and zirconates in terms of thermal and electrochemical properties, while there is still room for further improvements.
Defect Thermodynamic Modeling of Triple Conducting Perovskites (La,Ba)Fe1-xMxO3-δ for Proton-Conducting Solid-Oxide Cells
Authors: Lee Yueh-Lin , Duan Yuhua , Sorescu Dan C. , Saidi Wissam A. , Morgan Dane , Kalapos Thomas , Epting William K. , Hackett Gregory A. , Abernathy Harry W.
Published: May 2023

Both the experimental and first-principles modeling results revealed the dependence of defect energetics on oxygen non-stoichiometry and magnetic coupling of Fe in the Fe-based perovskite oxides. A generalized defect thermodynamic model of the proton-conducting (La,Ba)Fe1-xMxO3-δ perovskite oxide is developed to allow inclusion of nonlinear δ dependent terms in three key defect reaction energies, namely, the oxygen vacancy formation, hydration, and charge disproportionation reactions. A transition from a large polaron description at lower δ values to a small polaron expression at higher δ is also considered in our analysis. Based on the functional forms of defect energetics on δ as guided by first principles modeling and literature data, the Brouwer diagrams of BaFe0.9Y0.1O3-δ are assessed to provide information on electronic and ionic defect concentration (including the proton species) as a function of O2 and H2O pressure at different temperatures for solid-oxide cell applications.
Reversible Solid Oxide Cells: Selection of Fuel Electrode Materials for Improved Performance and Durability
Authors: Sasaki Kazunari , Natsukoshi Katsuya , Yamada Kei , Ikegawa Kazutaka , Yasutake Masahiro , Tachikawa Yuya , Lyth Stephen Matthew , Matsuda Junko , Yildiz Bilge , Tuller Harry L.
Published: May 2023

Different fuel electrodes for reversible solid oxide cells (r-SOC) are investigated with the aim of improving performance in both solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) modes, and durability in reversible operation mode. Electrodes based on gadolinium-doped ceria (GDC) as a mixed ionic electronic conductor, and lanthanum-doped strontium titanate (LST) as an electronic conductor are selected. The current-voltage characteristics of r-SOC single cells, and their cycling durability up to 1000 cycles are evaluated. LST-GDC co-impregnated with Ni and GDC prove to be highly durable in reversible operation, as a suitable fuel electrode material for r-SOCs.
Life Testing and Redox Cycling of Ni- and Ru-Doped Strontium Iron Titanate Exsolution Fuel Electrodes in Electrolyte-Supported Solid Oxide Cells
Authors: Zhang Yubo , Horlick Samuel A , Dogdibegovic Emir , Barnett Scott A
Published: May 2023

Oxide exsolution fuel electrodes for solid oxide cells (SOCs) have shown good initial electrochemical performance compared with conventional Ni-YSZ. Few studies have focused on investigating the long-term durability of these materials and no long-term reversible operation has ever been conducted on cells with these exsolution fuel electrodes. In this study, life tests on electrolyte-supported full and symmetric cells with Sr0.95Ti0.3Fe0.63Ni0.07O3-
d (STFN) and Sr0.95Ti0.3Fe0.63Ru0.07O3-
d (STFRu) fuel electrodes were conducted under different testing conditions. STFN fuel electrodes tested with 97% H2 +3% H2O showed worse initial stability than cells tested with 50% H2 +50% H2O; this is attributed to a more extensive perovskite-RP phase transformation, as suggested by in-situ X-ray diffraction (XRD) analyses. STFRu was also tested with 97% H2 +3% H2O and showed better stability than STFN.
Waste2Watts: Techno-Economic Feasibility of Biogas-Fed SOFC Power System Integrated with Biogas Cleaning Unit and Carbon Capture Technologies
Authors: Yu Hangyu , Wang Ligang , Van herle Jan , Pina Eduardo Antonio
Published: May 2023

Solid oxide fuel cell (SOFC) systems show immense potential for efficient biogas utilization, which can significantly reduce carbon emissions by integrating with biogas cleaning units and carbon capture technologies. Despite the significant benefits, the high cost of the integrated system presents a challenge. Therefore, a techno-economic assessment is necessary to evaluate the feasibility of the integrated system and provide guidelines for cost reduction. The ideal capacity for an integrated biogas-fed SOFC power system ranges between 20 kW to 200 kW. Firstly, a comparison of different biogas types and stack technologies is conducted to evaluate the system performance. Secondly, a techno-economic investigation of the feasibility of different system designs is performed by comparing different carbon capture technologies with various biogas cleaning units. The study results can facilitate the optimization of the integrated system's design and operation and pave the way for large-scale implementation of SOFC technology in the energy industry.
Direct Ammonia SOFC-Gas Turbine Hybrid Systems Modeling for Heavy-Duty Transportation Sector
Authors: Ashar Akhil , Wehrle Lukas , Deutschmann Olaf , Braun Rob J
Published: May 2023

Solid oxide fuel cells (SOFCs) have the potential to run on ammonia without the need for any pre-reforming and therefore enable effective energy conversion of ammonia to power. In this work, an ammonia based SOFC-Gas turbine (GT) system concept is proposed and assessed for the mobility sector. The model integrates a three-dimensional multiscale SOFC stack simulation based on a validated Ni-GDC/GDC/SSC button cell model with balance-of-plant component modeling. This work discusses the thermodynamics of SOFC operation and system concepts to utilize ammonia in a hybrid system for a kW-scale transportation application. System indicators and performance metrics such as efficiency, electrochemical utilization and turbine inlet temperature are evaluated and optimized. The proposed hybrid system is computationally predicted to reach efficiencies of up to 60% for pressurized operation.
Local Structure and Mixed Proton-Hole Conduction in Y and Al-Doped BaZrO3
Authors: Oikawa Itaru , Kimura Koya , Ishii Akihiro , Takamura Hitoshi
Published: May 2023

Enhancing proton-hole mixed conduction is one of the promising methods to improve the cathode performance of proton-conducting fuel cells. In this study, Al-doping is conducted to enhance the hole conduction in Y-doped BaZrO3. The relationship between the defect structure around Al and the electrical conductivity is investigated. 27Al NMR results indicated the formation of more than one oxygen vacancy around Al and the clustering of the acceptors. The electrical conductivity shows dominant proton conduction below 600ºC while other charge carriers, such as oxygen vacancies and electron holes, dominate at 800ºC. The Al-doping affects the formation of the defects but shows negligible influence on the dominant charge carriers at lower temperatures.
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: May 2023

Ammonia-fueled solid oxide fuel cells (SOFCs) have attracted the focus of researchers due to no carbon emissions in utilization. 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 difficulty in distinguishing the anode reaction mechanism. In the present study, we utilized a patterned anode to obtain a designed triple phase boundary (TPB) and avoid the effects of porous electrodes. In the performance test, we found that the exchange current density of the NH3-fed SOFC was approximately 5% of that of the H2-fed SOFC under a similar working position at 700℃. The difference may mainly result 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.
The Coating Effect on Interconnect Materials After >10 Years of Furnace Exposures
Authors: Norrby Niklas , Li Shunyi , Stenström Mikael , Westlinder Jörgen
Published: May 2023

The present work has studied the effect of subjecting an AISI 441 ferritic stainless steel in a box furnace exposure in air at 800 °C for up to 10 years. During operation, the mass gain was repeatedly measured at selected time intervals. The results show that there are only small differences in spinel composition when a sample exposed for ~5 years is compared to a sample exposed for 10 years, with the main difference being a growth of the chromia scale from ~10 to ~14 µm. In addition, the chromium content is 12.3 wt-% after 5 years whereafter it is further reduced to 10.5 wt-% during the following exposure time. Despite a relatively low chromium content already after 5 years, there are no visible signs of material failure, e.g, neither spallation nor a a large increase in mass gain during the 10 years in the furnace.
Electrophoretically Deposited Protective Cu-Mn and Mn-Co Spinel Coatings for SOFC Interconnects
Authors: Basu Soumendra , Zhu Zhikuan , Mulligan J.R. , Pal Uday , Gopalan Srikanth , Abdul Jabbar Mohammed Hussain , Dale Nilesh , Fukuyama Yosuke , Miura Yohei , Miyoshi Yutaro
Published: May 2023

Stainless steel interconnects in solid oxide fuel cells can lead to chromium poisoning of the cathode, necessitating the use of protective coatings. Electrophoretic deposition is an efficient method to deposit coatings on substrates with complex microstructures. In this study, four spinel coatings; CuMn2O4, CuNi0.2Mn1.8O4, MnCo2O4, and MnFe0.34Co1.66O4, were deposited by direct-current electrophoretic deposition on flat SUS430 stainless steel substrates. The coatings were evaluated on multiple criteria, including microstructural stability, conductivity, Cr gettering ability, and the ability to act as a diffusion barrier at 700°C and 800°C. It was concluded that CuNi0.2Mn1.8O4 is an excellent candidate at temperatures at and below 700oC, while MnFe0.34Co1.66O4 coatings perform better at higher temperatures.