bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidation Process of Ni Cathode in CO2 Electrolysis in SOEC: X-Ray and DFT Study
Authors: Watanabe Hirotatsu , Higashidani Syo , Tawa Aoba , Ban Ikken , Ogura Teppei 
Published: September 2023

Solid oxide electrolysis cells (SOECs) can convert H2O and CO2 to syngas(H2/CO) at high temperature, promising a way in the power-to-gas process. A Ni electrode such as nickel/yttria-stabilized zirconia (Ni/YSZ) and nickel/scandia-stabilized zirconia (Ni/ScSZ) have widely used as a cathode for SOECs. Meanwhile, the cathode faced severe oxidizing condition due to a high steam and CO2 content. H2, a reduction agent, can inhibit the cathode oxidation; however, an additional H2 decreases a total energy efficiency. Oxidation tolerance is an important parameter for the material candidate as the cathode. A combination study of X-ray and DFT study is a promising way to understand oxidation mechanisms of Ni cathode, which provides an useful hint in the cathode design with oxidation tolerance.
In this study, oxidation process of Ni cathode in CO2 electrolysis was studied using X-ray and density functional theory (DFT). Ni cathodes (Ni/YSZ, Ni/ScSZ) were used in H2/CO2 environment under the electrolysis mode. After CO2 electrolysis, Ni cathode surface was analyzed using SEM/EDS and X-ray diffraction (XRD). Influence of H2/CO2 ratio and operating condition on cathode oxidization was studied in the electrolysis mode. All calculations here are performed employing the plane wave density functional theory (DFT) method implemented in the Vienna Ab-Initio Simulation Package (VASP).
XRD results showed that the cathode oxidation was progressed at H2/CO2 ratio of 0, whereas the cathode oxidation was inhibited when the H2/CO2 ratio was higher than 0.75 at 800 oC. In addition, it was suggested that the electrolysis mode, in which oxygen was moved from the cathode to the anode, had a role in inhibiting the cathode oxidation. In the DFT calculation, an activation energy of CO2 decomposition at the triple phase boundary (CO2→CO+O,vacancy) was much lower than that at the Ni surface (CO2→CO+O,Ni), indicating that CO2 electrolysis was more preferable than Ni oxidation. It was shown that the electrolysis mode can enhance the oxidation tolerance of Ni cathode. Moreover, Ni/YSZ and Ni/ScSZ cathode were also studied in terms of CO2 electrolysis and oxidation. The activation energy of CO2 decomposition of Ni/ScSZ was lower than that of Ni/YSZ mainly because O can easily enter the vacancy in the ScSZ. It was shown that the oxidation can be controlled from the electrolyte structure in the electrolysis mode.
Electrochemical Performance of Direct Ammonia Solid Oxide Fuel Cell
Authors: Lee Sanghwa , KIM Jooeon , Kim Kyungsun , Hwang Haejin 
Published: September 2023

Recently, as regulations on greenhouse gas emissions have been strengthened in various industries such as automobiles and ships, many studies on alternative energy are being conducted. Hydrogen is a good energy carrier and an environmentally benign fuel because the reaction product is only water or water vapor when it is burned or is used for fuel cells. However, hydrogen suffer from its low specific volume, so the storage issue is still remained unsolved.
Ammonia (NH3) has a higher energy density (12.7 MJ/L) than liquid hydrogen (8.5 MJ/L). Liquid hydrogen has to be stored at cryogenic conditions of –253°C, whereas ammonia can be stored at a much less energy-intensive –33°C. In addition, ammonia is much less flammable than hydrogen although it is hazardous to handle.
In this study, anode-supported SOFCs consisting of LSCF-GDC cathode, YSZ electrolyte, and Ni/YSZ cermet anode was fabricated and their electrochemical performances (Impedance spectra, J-V curve and cell voltage degradation with operation time) were investigated at 600, 650, and 700°C under ammonia and hydrogen. Regardless of the operating temperature, the power densities of ammonia-fueled SOFCs were almost similar to those of hydrogen-fueled SOFCs. This suggested that the ammonia cracking reaction effectively occurred in the Ni-YSZ anode support. However, the cell voltage at 0.2 A/cm2 was slightly decreased as a function of operating time, which means that the nickel was degraded under ammonia atmosphere. The change of an anode’s microstructure before and after the degradation test will be discussed. In addition, Ni-YSZ catalysts for ammonia cracking were fabricated and their catalytic activity was measured in terms of operating temperature and space velocity using in-line gas chromatography. The phase evolution and microstructure of catalysts were characterized by XRD, SEM and TEM.
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: September 2023

Solid oxide technology allows to produce synthesis gas (CO+H2), a relevant mixture and precursor for e-fuels and other products in the chemical industry. This work reports on the long-term performance of an electrolyte supported cell (Ni-CGO/3YSZ/LSCF-CGO), operating at industrially relevant co-electrolysis conditions (32.5 % H2/35 H2O/8.1 CO/24.4 CO2, -0.5 A/cm2, 816 °C). The applied cell had a Ni-CGO fuel electrode (~30 μm thick), a 3YSZ electrolyte (~90 μm) and an LSCF-CGO oxygen electrode (~35 μm thick) including a thin CGO protective layer.
The cell was operated successfully for 2300 h at constant galvanostatic test conditions, with an overall degradation of 80 mΩ cm2/kh, which is a higher degradation rate than the reported for similar cells at comparable conditions. 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 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 falls and stabilizes during the last app. 2 kh of the long-term operation of the cell to 32 mΩcm2/kh. The increase in ohmic resistance is in percentage small but steady at 7 %/kh, while the increase in polarization resistance follows the same trend as the ASR.
Electrochemical impedance spectroscopy (EIS) showed a decrease of 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 species was found in the active area of the Ni-CGO fuel electrode.
Evaluation of Electrolytic Characteristics with a Single Cell Developed as SOFC
Authors: Imabayashi Takumi , Asano Koichi , Mugikura Yoshihiro 
Published: September 2023

In recent years, it is concerned that a power supply and demand balance of power grid become unstable because of large introduction of variable renewable energy such as solar photovoltaic power generation. The reversible solid oxide cell (rSOC) can operate both SOFC and SOEC modes reversibly. Therefore, the rSOC can be used as a flexibility device for the power supply and demand adjustment by operating reversibly in response to power grid balance.
Furthermore, CO2 electrolysis and co-electrolysis, which can generate synthesis gases such as H2 and CO, which are raw gases for methane or liquid fuels, from CO2 and H2O by adding an electric power, are promising carbon recycling technologies.
In this study, the electrolytic characteristics were evaluated with a single cell developed as SOFC. It was confirmed in CO2 electrolysis test that CO2 can be directly electrolyzed to CO with about 100% current efficiency. In addition, the electrolysis voltages were clarified under various gas conditions in co-electrolysis and the cell performance factors were analyzed by our original method. In this method, the cell performance factors can be described by the internal resistance loss (IR loss, measured value), the fuel electrode overvoltage, the oxygen electrode overvoltage, and the Nernst loss (calculate value). As a result of this analysis in co-electrolysis mode before and after all tests, it was shown that the increase in IR loss was the main factor of the decrease in cell performance.
Interface Resistance Analysis in Solid Oxide Fuel Cells
Authors: Yoo Hyun Sik , Megra Yonas , Suk Ji Won , Lee Wonyoung 
Published: September 2023

A sophisticated design of the interface structure between the cathode and the electrolyte is essential to improve the performance of solid oxide fuel cells (SOFCs). It is because the interface is the place where it directly affects both the ohmic resistance and the polarization resistance as interface contact and interface reaction, respectively. To improve interface properties, electrolyte surface treatment or inserting interface functional layer between the cathode and the electrolyte have been applied. They improved cell performance by effectively enhancing the interfacial characteristics such as interface bonding and interface reaction area. However, although both ohmic and polarization resistance greatly contributed to the improved cell performance, a detailed analysis related to ohmic resistance compared to polarization resistance is insufficient. Unlike polarization resistance which can quantify interface reaction related resistance using distribution of relaxation time (DRT) model, there is no proper methodology to quantify interface resistance in the case of ohmic resistance. The interface resistance has been analyzed to the extent that it belongs to the remaining resistance except for the electrolyte resistance from total ohmic resistance in consideration of the ionic conductivity and thickness of the electrolyte, which still not completely separate the interface resistance from the total ohmic resistance. Furthermore, in recent years, the electrolyte thickness has gradually decreased to less than 5 μm for high-performance and the electrolyte resistance has been significantly reduced, increasing proportion of interface resistance in total ohmic resistance. Therefore, we need to reduce the interface resistance for further cell improvement. Also, quantifying the interface resistance and having a deeper understanding of the correlation between interface resistance and interface structure should be supported.
Here, to realize the interface resistance from the ohmic resistance, we designed several types of interface structure using electrostatic spray deposition (ESD) which can precisely control the particle size and be used to fabricate a thin functional layer. Using the different interface properties and equivalent circuit models, we separate the interface resistance from the ohmic resistance quantitatively. Our results can suggest a simple and effective interface analysis method for achieving high performance SOFCs.

Figure 1
Solid Oxide Stack Development at Elcogen
Authors: Noponen Matti , Puranen Jouni , Alfano Antonio , Granö-Fabritius Hanna 
Published: September 2023

Elcogen is one of the leading European manufacturers of solid oxide cell (SOC) and stack technologies. Elcogen stacks are a unique combination of best-in-class performance and low-cost product structure. The stack products are designed for low temperature operation enabling major cost reductions on the system level. This article summarizes the recent activities and development trends of Elcogen.
Elcogen solid oxide technology can be used both in electrolysis and fuel cell mode. In electrolysis mode, steam is converted with electricity into green hydrogen. The electrolysis technology can also be used to produce syngases for e-fuel production by combining steam and carbon dioxide. Elcogen technology can be operated at high conversion efficiency level with a variety of fuels in the fuel cell mode.
Elcogen is currently focused on ramping up its unit cell and stack production with increased customer demand. The goal is to set-up of a manufacturing plant for stacks with annual capacity close to 200 MW in electrolysis mode.
Solid Oxide Fuel Cells for Aviation
Authors: Nehter Pedro , Geisler Helge , Ahilan Vignesh , Friedl Stephan , Rohr Oliver , Walter Aurelie , Metzner Christian , Zimmermann Kristian 
Published: September 2023

Airbus has revealed ZEROe, three concepts for the world’s first zero-emission commercial aircraft which could be brought to market by 2035. The ZEROe concept aircrafts, which support Airbus’ commitment to lead the decarbonisation of the aviation industry, all rely on hydrogen as a primary power source, which would be deployed via a hybrid-hydrogen configuration featuring modified gas-turbine engines complemented by fuel cells for electrical power. Although the Proton Exchange Membrane (PEM) technology is one of the most matured fuel cell types, Airbus Central Research and Technology (CRT) is also investigating novel SOFC concepts for potential hybrid-hydrogen configurations.
The Solid Oxide Fuel Cell (SOFC) offers major benefits, namely electrical efficiency and fuel versatility, for hybrid-electric aircraft propulsion. Although the SOFC’s area specific power density has drastically increased within the last decade, more needs to be done to make the technology accessible for aviation applications. The combined development of novel SOFC concepts and corresponding manufacturing processes are regarded as key objectives for the SOFC activities at Airbus Central Research and Technology. Airbus is designing, manufacturing and testing SOFC concepts with the aim to achieve highest gravimetric power densities.
Novel manufacturing technologies for metallic and ceramic materials have the potential to enable lighter functional layers for SOFCs with increased intrinsic mechanical stability and surface area. Different cell concepts with an optimized current collection are currently under development at Airbus. The micro-tubular and monolithic SOFC are seen as the most promising concepts, whereas around 2 kW/kg on a cell level has recently been achieved in a performance test at Airbus.
Multi-Flanges for Intensive Cell Development and Lct Forlarge Cell and Stack Evaluation
Authors: Ihringer Raphael , Girardon Jean , Coquoz Pierre 
Published: September 2023

Two new test benches have been developed at Fiaxell. One is the multi-Flanges allowing to test 4
cells in one run. All the functionalities of the Open flanges, such as integrated steamer, real or ideal
condition testing, ceramic housing on air side, gas processing are kept apart short stacking.
The second test rig is the LCT for Large Cell Tester. It has been designed for cell dimension
starting from 90 X 90 mm and ending with the size of 130 mm X 170 mm. Again all the Open
Flanges functionalities are kept. The LCT is no delivered for short stack of maximum 3 cells. In the
second part of 2022, heat exchanger made with proper material will be ready for market. It will
allows to test up to 30 cells.

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Investigation of the Electrode-Electrolyte Interfaces in Solid Oxide Cells
Authors: Lenser Christian , Schwiers Alexander , Ramler Denise , Menzler Norbert H. 
Published: September 2023

The interfaces between electrodes and electrolyte are critical locations in a solid oxide cell (SOC). These interfaces originate from the chemical interaction of two different materials during processing, and are therefore very sensitive to the chemical nature of the materials, as well as the thermal history of the cell. On the air side, perovskite air electrodes tend to form insulating zirconates when sintered on stabilized zirconia, the most common electrolyte material. On the fuel side, using an ionic conductor with a different chemical composition as zirconia can lead to pronounced interdiffusion and the formation of new phases.
Interlayers of doped ceria are frequently used in order to suppress these undesired chemical reactions between electrodes and stabilized zirconia electrolytes. Prior investigations have focused extensively on the chemical composition of the interface and its consequences for cell performance. The focus of this contribution is the microstructure of the interface, as well as the microstructural development during processing.
On the fuel side, the interdiffusion of ceria and zirconia is known to lead to an intermixed phase with decreased conductivity. However, the reduced cell performance of anode-supported cells with Ni-GDC electrodes cannot be explained by an increase in the electrolyte resistance alone. We show that the formation of porosity due to a difference in the diffusion coefficients of ceria and zirconia leads to an increase in the fuel electrode polarization, and investigate possible countermeasures. It is shown that specifically the presence of NiO leads to the formation of porosity at the interface.
On the air side, we investigate the role of a dense interdiffusion layer between ceria and zirconia on the air electrode polarization. We confirm that only a dense interdiffusion layer is necessary by using Pr-doped ceria as a barrier layer, which delaminates after sintering and leaves behind a submicron barrier layer. Finally, we investigate the hypothesis that the densification of the barrier layer during air electrode sintering is essential for electrode adhesion and performance.
On Electrochemically Driven Phase Change and Accelerated Test Protocols in Solid Oxide Cells
Authors: Zhou Xiao-Dong , Wang Yudong , Dogdibegovic Emir 
Published: September 2023

The aim of this talk is to address three fundamental questions in solid oxide fuel cells and solid oxide electrolysis cells:
(1) Whether or not the oxygen reduction reaction is indeed the limiting step in solid oxide cells and how to quantify it definitely?
(2) What is the origin for the so-called “electrochemically driven phase transformation and how to translate the understanding to achieve a high-performance and highly stable electrode?
(3) How to develop reliable accelerated test protocols and what’s the physical process that was accelerated?
Quantifying electrode polarization in fuel cells and electrolyzers is of significant importance. It, however, remains difficult because of the substantial overlap of polarizations from both negative and positives electrodes either in a dc or an ac measurement. This challenge leads to a compelling gap in our scientific understanding of electrode phenomena and designing high-performance and durable electrochemical devices. In this talk, we will describe a reproducible method to quantify the polarization of an individual electrode of a solid oxide cell. This method is generic and can be applied readily to other electrochemical cells.
We will then address the greater phase transformation of an oxygen electrode during operation when compared to thermally annealed powders. Theoretical analysis suggests that the presence of a reduced oxygen partial pressure at the interface between the oxygen electrode and the electrolyte is the origin for the phase change in an oxygen electrode. Guided by the theory, an addition of the electronic conduction in the interface layer leads to the significant suppression of phase change, while improving cell performance and performance stability.
Reliable accelerated test protocols are needed for solid oxide fuel cell research to facilitate rapid learning on key durability issues, identify potential modes of failure expeditiously, and eventually predict the calendar lifetime of an electrochemical cell. In this work, solid oxide fuel cells operated at a constant current density were compared to cells undergoing accelerated measurements, which are composed of intermittent current injection to the cell. A general accelerated test profile was developed by cycling a solid oxide fuel cell from open circuit to a predetermined operating current density that is the same as the current density during a steady-state operation, to accelerate the local redox environment. Up to 1,320,000 cycles were generated in this work. The cell degradation was accelerated by nearly 10×, suggesting the feasibility of using this protocol for acceleration test to predict life performance of solid oxide fuel cells.
Finally, we will present a theoretical model that underlies those three questions and can be used to address stability and durability issues in solid oxide fuel cells and solid oxide electrolysis cells.
Durability and Interfacial Elemental Diffusion about BZYb based Protonic Ceramic Fuel Cell
Authors: Mikami Yuichi , Yamauchi Kosuke , Kuroha Tomohiro , Shimada Hiroyuki , Mizutani Yasunobu , Matsuda Ryuma , Mori Masashi , Okuyama Yuji 
Published: September 2023

Protonic ceramic fuel cells (PCFCs) are expected to be a highly efficient next-generation fuel cell because the fuel is not diluted by the generated water vapor during power generation. In the past research, we have found that Yb-doped BaZrO3 (BZYb) is promising in terms of the durability against CO2, proton conductivity, and less reactivity with NiO used for the fuel electrode. We are currently developing improvement of power generation efficiency and durability of PCFCs using BZYb electrolyte.
In terms of the durability of PCFCs, there is concern about degradation due to diffusion of transition metals such as Co and Ni used in the air and fuel electrodes. In this study, we evaluated the durability of PCFCs using BZYb electrolyte focusing on the diffusion of transition metals derived from electrodes. We also examined the effect of a buffer layer on the air electrode side.
In this study, fuel electrode supported cells with BaZr0.8Yb0.2O3-δ(BZYb20) electrolyte and NiO-BZYb20 fuel electrode was used. The fuel electrode half cells were fabricated by integrally firing process of the laminated green sheets of the electrolyte and fuel electrode to densify the electrolyte. For air electrode, BaZr0.375Yb0.125Co0.50O3-δ was screen printed on the fuel electrode half cell and fired at 900°C. For the cell with buffer layer between the air electrode and the electrolyte, BaCe0.7Zr0.1Y0.1Yb0.1O3-
δ was spin-coated on the half-cell and then fired at 1300°C. The air electrode was then prepared in the same way. Durability tests were conducted at constant-current mode at 600°C, and the elemental diffusion state of the cells before/after the test was observed by cross-sectional EPMA.
During 1000h power generation, the increase of ohmic resistance and polarization resistance was observed, and the increase in resistance was found to be smaller in cells with buffer layer. The results of cross-sectional EPMA analysis after the power generation test showed differences in the segregation state of Co and Ni in the electrolyte, with a tendency for segregation to be suppressed in the presence of a buffer layer.
Acknowledgement: This work is partially based on results obtained from a project (JPNP20003), commissioned by the New Energy and Industrial Technology Development Organization (NEDO) of Japan.