bluuebunny/crossref_metadata_2025_split huggingface dataset:
Boundaries of High-Temperature Co-Electrolysis Towards Direct CO2-Electrolysis
Authors: Wolf Stephanie Elisabeth , Dittrich Lucy , Nohl Markus , Foit Severin , Vinke Izaak , De Haart L. G. J. , Eichel Rudiger-A 
Published: July 2021

High-temperature co-electrolysis of CO2 and H2O at elevated temperatures between 700 °C and 900 °C valorises CO2 to produce a mixture of carbon monoxide (CO) and hydrogen (H2), called syngas. Co-electrolysis has the great advantage over conventional processes, that the desired syngas ratios of downstream processes can be realized by varying process parameters such as temperature and feed gas composition accordingly in a one step process. Co-electrolysis can also play a vital role in counteracting power fluctuations of renewable energy sources by storing temporarily unused electricity through conversion to other energy resources like chemicals or heat for later use.
The underlying processes in co-electrolysis for CO production are direct electrochemical CO2 reduction and reverse water gas shift equilibrium (RWGS). Their specific significance has not been clarified in detail yet and was controversially discussed in literature up to this day [1,2].
The impact of the equilibrium partial pressure of H2O on the physical processes in the transition boundary of co-electrolysis towards direct CO2-electrolysis was investigated by AC and DC measurements for various gas compositions. The analysis led to identifying the role of the underlying electrochemical processes during co-electrolysis, in particular the electrochemical CO2 reduction compared to the conversion of CO2 in the reverse water-gas shift reaction and the electrochemical H2O reduction. The area specific resistance (ASR) was, amongst others, taken as an indicator to determine, which of the reduction reactions (H2O or CO2 reduction) is dominant depending on the gas composition. The experiments were conducted using commercially available cathode-supported full cells (Elcogen) made of Ni-8YSZ/8YSZ/CGO/LSC.
Results as seen in Figure 1 show that the ASR for an equilibrium concentration of 5 % H2O is considerably larger than for higher H2O contents. Above 15 % H2O, the ASR shows no dependency on the gas composition and is comparable to pure H2O-electrolysis [3]. These observations underline the hypothesis that CO2-electrolysis becomes pre-dominant compared to H2O-electrolysis for low H2O content during co-electrolysis. With increasing H2O content, CO2-electrolysis becomes less significant and carbon dioxide is converted in the reverse water gas shift equilibrium. The origin of the discrepancy in literature was found to be the different operating H2O concentrations. A threshold has been established for the perception of CO2-electrolysis during co-electrolysis experiments.
figure caption: Arrhenius plot of ASROCV for different steam concentrations at 6 l·h-1.
[1] C. Stoots, J. O'Brien, J. Hartvigsen, Int. J. Hydrogen Energy 2009, 34, 4208.
[2] S. D. Ebbesen, R. Knibbe, M. Mogensen, J. Electrochem. Soc. 2012, 159, F482-F489.
[3] L. Dittrich, M. Nohl, E. E. Jaekel, S. Foit, L.G.J. (Bert) de Haart, R.-A. Eichel J. Electrochem.
Soc. 2019, 166, F971-F975.

Figure 1
Influence of Active Layer Thickness of Reversible Solid Oxide Cells on the Electrochemical Performance of Water Electrolysis
Authors: Kukk Freddy , Pylypko Sergii , Lust Enn , Nurk Gunnar 
Published: July 2021

As energy storage becomes increasingly more important in contemporary and future energy solutions, the ability of a solid oxide cell (SOC) to work reversibly as an electrolyzer/fuel cell gives this technology great potential for use in large energy storage projects1,2. In theory, it is possible to use the state-of-the-art solid oxide cells in electrolysis operation to produce fuel (i.e. split water into oxygen and hydrogen) or generate electricity and heat using the so-called fuel cell regime. In addition, it is possible to produce syngas (H2 + CO)1,2 by co-electrolyzing water and CO2.
While the performance and stability of the solid oxide fuel cell (SOFC) are in focus of most research regarding this technology, the technological possibilities of reversible solid oxide cells (RSOC) are far less studied. Although both technologies mostly share their device composition and main architecture, using the SOC in electrolysis mode creates new degradation mechanisms and technological problems3,4.
In this work the authors focus on the electrolysis performance of the RSOC. The authors analyzed the influence of active layer thickness on SOC performance in electrolysis mode by using a commercial solid oxide cell (Ni-3YSZ|Ni-8YSZ|8YSZ|GDC|LSC). The study has been performed to establish the optimal active layer thickness and therefore to maximize the SOC performance in electrolysis mode.
Electrochemical characterization of SOC button cells has been conducted using electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic methods at several operating conditions including different temperatures and different water vapor contents in the gas stream. The gas compositions have been exchanged to simulate working conditions at different locations in the RSOC stack during electrolysis work. The results of the electrochemical studies have been analyzed using equivalent circuit fitting method of Nyquist plots. Complex analysis of different porous architectures and chemical compositions at different operating conditions gave more information on how the structure of the SOC determines the electrochemical performance of the water electrolysis process.

References:

Giulio Vialetto, Marco Noro, Paolo Colbertaldo, Masoud Rokni, International Journal of Hydrogen Energy, 44, 9608-9620 (2019)

M. B. Mogensen, M. Chen, H.L. Frandsen, C. Graves, J.B. Hansen, K.V. Hansen, A. Hauch, T. Jacobsen, S.H. Jensen, T.L. Skafte and X. Sun, Clean Energy, 3, 175–201 (2019)

P. Mocoteguy and A. Brisse, International Journal of Hydrogen Energy, 38 (36), 15887-15902 (2013)

Y. Tao, S. D. Ebbesen, M. B. Mogensen, Journal of Power Sources, 328, 452-162 (2016)
Tuning Transport Mechanisms in Fuel-Assisted Solid Oxide Electrolyzers for Enhanced Performance and Product Selectivity
Authors: Nielsen Anders S , Pharoah Jon G 
Published: July 2021

The demand for renewable energy storage systems and CO2-utilization technologies has become apparent in recent decades due to concerns related to the continuous emission of anthropogenic greenhouse gases. A promising technology that can help alleviate some of these concerns are solid oxide electrolyzers, since they have the ability to convert CO2 and steam into valuable chemicals and fuels from the electricity generated by renewable sources, including wind and solar energy. Furthermore, these devices can operate in fuel-assisted mode, wherein a reactant, such as methane, hydrogen, and/or carbon monoxide, is delivered to the anode in order to reduce its operating potential. This simple modification has been shown to decrease the operating potential by nearly one order of magnitude [1-3], and, in some instances, has enabled the cell to generate power and synthesis gas simultaneously [4-6]. Fuel-assisted solid oxide electrolyzers have therefore emerged as a compelling option for renewable energy storage and large-scale chemical production, and have begun to draw significant attention from researchers and designers. But despite previous efforts, an understanding of how to attain a desired product composition and efficiency remains unclear. The objective of the presented work, then, is to perform a scaling analysis of the transport phenomena pertinent to fuel-assisted cells, in order to develop a set of dimensionless ratios that characterize the interplay between chemical and electrochemical reactions, and advective and diffusive transport. These dimensionless ratios provide crucial information on how to control the contribution of chemical and electrochemical reactions, as well as strategies to mitigate concentration and temperature gradients within the electrodes and flow channels. This approach is intended to provide an enhanced understanding of how to increase the product selectivity and performance of fuel-assisted solid oxide electrolyzers, which will hopefully lead to enhanced electrode and cell designs.
[1] A. Q. Pham, P. H. Wallman and R. S. Glass, US Patent 6,051,125 (2000).
[2] F. Chen and Y. Wang, US Patent 9,574,274 (2017).
[3] Y. Wang, T. Liu, S. Fang, G. Xiao, H. Wang and F. Chen, J. Power Sources, 277, 261 (2015).
[4] H. Xu, B. Chen and M. Ni, J. Electrochem. Soc., 163, F3029 (2016).
[5] Y. Patcharavorachot, S. Thongdee, D. Saebea, S. Authayanun and A. Arpornwichanop, Energy Convers. Manage., 120, 274 (2016).
[6] H. Xu, B. Chen, J. Irvine and M. Ni, Int. J. Hydrogen Energy, 41, 21839 (2016).
Spatial Current and Temperature Variations in a Microtubular Solid Oxide Electrolysis Cell In-Situ Analyzed with Electrode-Segmentation Method
Authors: Xuefeng Wang , Nakajima Hironori , Ito Kohei 
Published: July 2021

The spatial distribution of current and temperature plays important role in the electrochemical performance of Solid Oxide Electrolysis Cells (SOECs). Many numerical predictions of current and temperature distribution have been reported, whereas experimental investigations were rare. In this research, we are applying a electrode-segmentation [1] method to investigate the spatial current and temperature variation in a cathode-supported microtubular SOEC. The electrode-segmentation method shows a remarkable current variation among the segments. The current densities of the midstream and downstream segments are smaller than the upstream segment with an increased cell voltage, implying that the cell suffers from water starvation. Besides, the temperature at each segment increases with the voltage increase. The largest current in the upstream segment is observed, which agrees with the largest temperature rise there. The largest temperature gradient happens between the upstream and midstream segments.
References

Aydin, T. Koshiyama, H. Nakajima, T. Kitahara, Journal of Power Sources, 279, 218-223 (2015).
Enhancing the Catalytic Activity of Lanthanum-Ceria Fluorite for Methane Conversion in SOFC
Authors: Vilela Vanessa Bezerra , Thyssen Vivian Vazquez , Rodrigues Lays Nunes , Fonseca Fabio Coral 
Published: July 2021

A2B2O7 compounds have unique properties, such as good thermal stability, oxygen mobility, ionic conductivity, etc. Such compounds with tailored compositions exhibit good catalytic properties in a variety of high-temperature reactions, such as reform and oxidative coupling of methane (OCM). An effective catalyst for OCM must have electrophilic oxygen mobility and alkalinity on its surface. A typical A2B2O7 compound that contains a trivalent rare earth metal at site A, such as La, can provide the necessary surface alkalinity for a good OCM catalyst. Previous studies show that La2Ce2O7 (LCO) catalysts perform well in OCM due to the selective mobile oxygen sites, suitable alkaline sites, and high thermal stability. Doping LCO with Ca increases the alkalinity, which can considerably increase selectivity for ethylene in the OCM reaction. We have studied calcium-doped lanthanum ceria materials as a catalytic layer in solid oxide fuel cells reactors for methane conversion to ethylene. We have explored the combustion synthesis to obtain homogeneous La2-xCaxCe2O7 powders with x = 0, 0.25, and 0.50 (LCO, LCa25, and LCa50, respectively). X-ray diffraction (XRD) showed that the calcium addition in LCO formed a single-phase solid solution. The crystalline structure of the synthesized materials is the disordered fluorite-type, as indicated by both XRD and Raman analysis. Raman spectroscopy data evidenced the presence of surface oxygen vacancies on all materials, which may benefit the OCM reaction. SEM images of as-prepared powders obtained evidenced a similar microstructure composed of porous sponge-like agglomerated particles with irregular shape, expected from the combustion synthesis (Fig. 1). Ca-doping changed the sintering behavior by reducing the onset of shrinkage during the sintering process. Impedance spectroscopy data showed increased ionic conductivity with increasing Ca-doping. Such an increase is more evident at high measuring temperature (800 oC) and indicates enhanced oxygen mobility that are expected to contribute to OCM reaction.
Figure 1: Scanning electron microscope micrographs of La2-xCaxCe2O7 (x = 0, 0.25, and 0.50) as-prepared powders obtained by combustion method.

Figure 1
Dry Surface Treatment Technology for the Design of the Anode Side of the Metal Support Solid Oxide Fuel Cell (MS-SOFC)
Authors: Ye Xiaolei , Luo Huan , Bertrand Pierre , Billard Alain , Briois Pascal 
Published: July 2021

As an electrochemical energy conversion device, solid oxide fuel cell (SOFC) has many advantages in energy conversion efficiency, fuel flexibility and environmental benefits. A typical high temperature SOFC possesses the advantages of high power density and high-grade waste heat production. However, high-temperature SOFC faces challenges in cost and long-term durability. Once the operating temperature of SOFC is effectively reduced, the fuel cell configuration anode supported can be changed to metal-supported SOFC (MS-SOFC). Alternative MS-SOFC designs have the advantages of low-cost material, robustness and convenient manufacturing.
In the present work, the metal supported half-cell with ITM / protective layer / Ni-YSZ / YSZ / GDC configurations were elaborated. Three protective layers of Co, Ce/Co and GDC were compared in terms of preventing Cr diffusion. Reactive magnetron sputtering (RMS) was used to deposit the electrolyte and the barrier layer because it can easily achieve a dense adherent and thin film. Atmospheric plasma spraying (APS) was used to deposit the cermet Ni-YSZ anode layer to facilitate the formation of porous structures. The morphology, microstructure and chemical composition of MS-SOFC were characterized by SEM, XRD and EDX, respectively. Finally, its electrical characteristics were measurements by four probe electrical and electrochemical impedance spectroscopy measurements.
Evaluation of Three-Dimensional Placement of Built-in Catalytic Partial Oxidation Catalyst in an Anode-Supported Honeycomb SOFC
Authors: Higa Tasuku , Nakajima Hironori 
Published: July 2021

Honeycomb solid oxide fuel cells (SOFCs) can achieve high power density with improved thermo-mechanical durability at high temperatures [1]. In this study, a compact SOFC with catalytic partial oxidation reforming catalyst embedded in the flow channels of a porous honeycomb anode support has been fabricated and evaluated. I-V measurements and gas chromatography for the outlet gas were carried out while methane/air mixture gas was fed as fuel. I-V measurements were performed to compare the performance of the two configurations: one with fuel supplied from the central channel and discharged from the surrounding four channels, and the other with fuel supplied from the four channels and discharged from the central channel. As a result, the effect of concentration overpotential was smaller in the latter case. The gas chromatograph detected hydrogen in the reformed gas for both cases.
Acknowledgments
Thanks are offered to Professor Kohei Ito of Kyushu University for valuable discussions.
References

H. Nakajima, S. Murakami, S. Ikeda, and T. Kitahara, Heat Mass Transfer, 54, 2545 (2018).
Electrical Conductivity of La0.9Sr0.1Ga0.8Mg0.2O3-D/La1.55Sr0.45Ga3O7+D Composite Electrolyte
Authors: Fujimoto Talita Gishitomi , Steil Marlu Cesar , Muccillo Eliana Navarro dos Santos 
Published: July 2021

Doped lanthanum gallate constitutes a family of solid electrolytes with high ionic conductivity, wide electrolytic domain and good chemical stability. The combination of their properties turns some compounds of this family, promising candidates for application in solid oxide fuel cells operating at intermediate temperatures. In this work, La0.9Sr0.1Ga0.8Mg0.2O3-δ - x La1.55Sr0.45Ga3O7+δ, with x = 0, 1 and 5 wt.% were investigated aiming to obtain a composite solid electrolyte with optimized properties compared to the parent material. Composite electrolytes were prepared by solid state reaction method and evaluated for densification, phase content and microstructure. Electrical conductivity measurements were carried out as a function of temperature and oxygen partial pressure.
Increase on densification and microstructural homogeneity were obtained with increasing fraction of the melillite phase. The electrical conductivity determined by impedance spectroscopy revealed a decrease of the grain resistivity for increasing amounts of La1.55Sr0.45Ga3O7+δ.
Influence of Sr2+ Concentration and A-Site Deficiency on Surface Stability of (La1
-
ySry)xCr0.5Mn0.45 Ni0.05O3
-δ
Authors: Kivi Indrek , Korjus Ove , Moeller Prit , Aruväli Jaan , Nurk Gunnar 
Published: July 2021

(La1–
xSrx)yCr0.5Mn0.45Ni0.05O3–

δ
(LSCMN) 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]. The material is catalytically active for oxidation of hydrogen and hydrocarbons [2]. A significant amount of attention has been paid to clarify the dependence between crystallographic and electrical properties of LSCM-based materials [1, 3]. Some papers also deal with stability issues if the material is used as an anode in a solid oxide fuel cell [3, 4]. So far, there is a lack of information about the dependence between A-site stoichiometry and stability of chemical composition- and electrochemical performance of LSCMN surface.
In this work, La/Sr ratio and deficiency of A-site, i.e. A-site stoichiometry of (La1–
xSrx)yCr0.5Mn0.45 Ni0.05O3–δ
were varied and chemical composition of LSCMN surface and electrochemical performance was monitored. The electrochemical measurements of symmetric cells (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 (segregation of some LSCMN components onto the surface and decomposition of perovskite phase) have a key role in the electrochemical performance of the electrode [3].
The electrode materials were analysed using XRD, TOF SIMS and electrochemical methods. XRD results for studied electrode powders showed significant dependence on the lattice parameters on the A-site composition. Materials were treated in two different gas environments – in synthetic air and in H2 environment, both at 1123 K for one hundred hours. TOF SIMS analysis demonstrated the dependence of the surface stoichiometry on the A-site stoichiometry of bulk electrode as well as on gas environment during heat treatment. 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 La/Sr ratio on the series- and polarization resistance of the electrode. The electrochemical activity and surface compositions were correlated and reasons of relative stoichiometric changes of the surface compared with bulk were discussed.

Yue and J.T.S. Irvine, Solid State Ionics, 225, 131 (2012).

Bidrawn, G. Kim, G. Corre, J.T.S. Irvine, J.M. Vohs, R.J. Gorte, Electrochem. Solid-State Lett. 11, B167 (2008).

Korjus, J. Aruväli, P. Paiste, K.Kooser, S. Granroth, H. Mändar, M. Kodu, R. Härmas, M. Maide, M. Ainsar, E. Lust, G. Nurk, Fuel Cell, 20, 6, 741 (2020).

C. Lu, J. H. Zhu, Solid State Ionics, 178, 1467 (2007).
Microstructure and Performance Analysis of Low-Temperature Solid Oxide Fuel Cells Synthesized on Inert Al2O3 Substrates
Authors: Solovyev Andrey , Shipilova Anna , Smolyanskiy Egor , Rabotkin Sergey , Semenov Vyacheslav , Matveev Danila 
Published: July 2021

In order to lower the SOFCs operating temperatures new electrolyte materials should be used instead of yttria-stabilized zirconia (YSZ) and the thickness of electrolyte should be decreased to the low micrometer range. To prepare the thin electrolyte, physical vapour deposition methods, such as magnetron sputtering, leading to dense, pinhole-free thin films, are ideal. If, additionally, also the anode and cathode materials are kept thin, low-temperature cells are obtained, also called micro-SOFCs.
To demonstrate the possibility of creating such thin-film layers, model anodes and anode/electrolyte systems were prepared on porous anodic aluminum oxide (AAO) substrates. As electrolyte material, Ce0.8Gd0.2O1.9-x (GDC) was used. The composite consisted of NiO and GDC was used as anode. The main advantage of GDC electrolyte for solid oxide fuel cells is four to five times higher ionic conductivity compared to YSZ in the temperature range 500-800°C.
The microstructure of NiO-GDC thin-film anode after reduction in hydrogen at temperatures of 450 and 600°С was studied. It was found that at these temperatures there is also agglomeration of Ni particles and segregation on the film surface in the form of small particles as in [1] at 850°C. It is also shown that annealing of the deposited NiO-GDC anode layer at 1000°С allows stabilizing its structure and excluding subsequent agglomeration of Ni particles during operation in a hydrogen atmosphere. Figure 1 shows the microstructure of NiO anode/GDC electrolyte system deposited on AAO substrate.
Button cells with a diameter of 13 mm and with different thicknesses of the anode and electrolyte were fabricated. A La0.6Sr0.4CoO3 cathode (Kceracell Co., Korea) was screen printed on the electrolyte surface and sintered in situ during cell testing in temperature range of 500–600°C. First investigations showed promising results, namely high open-circuit voltage values (0.8 V) and a power density up to 100 mW/cm² at 550°C in pure hydrogen. However, the impedance analysis of the cells points out that further anode and cathode optimization would be beneficial for the overall cell performance.
[1] F.J. Garcia-Garcia et al., Int. J. Hydrog. Energy, 40(23), 7382 (2015)

Figure 1: The microstructure of anode/electrolyte system deposited on AAO substrate (scanning electron microscopy)

Figure 1
Gas Containment Systems for Stationary and Mobile Applications
Authors: Nunic Radisa 
Published: July 2021

While green hydrogen production should remain the main target toward Zero Emissions Society, it would be prudent to maximize the utilization of easily accessible energy carries available already today in abundance.
Compressed Natural Gas (CNG) represents a widely available energy carrier. Approximately 4.000 CNG/LNG car filling stations are available, thus enabling CNG to be used as fuel for
commercial and personal vehicles based on the SOFC technology. Employing SOFC up to 30% higher efficiency can be achieved in comparison with conventional combustion engines. The
SOFC based vehicles fueled by CNG can thus represent a perfect intermediate solution toward CO2 reduction and elimination of NOx emissions.

Decentral power and heat generation via SOFC in combination with CNG offers yet another pathway to reach CO2 targets set by the European Union. Conditions for continued, more rapid growth of SOFC technology are favorable as global demand seeks different clean emissions heat and power generation solutions.

Worthington as a center of excellence is focused on the design and production of high-pressure cylinders and onboard fueling systems for mobile applications, like vehicle integration, gas transport containers and stationary storage solutions. Ensuring easier fuel storage and transport, application and commercialization of SOFC based systems for mobile application can be accelerated.
Worthington Industries is a global value-added steel processing company with headquarters in Columbus, Ohio, USA and production sites in Austria, Poland, and Portugal dedicated to pressure cylinder solutions for sustainable mobility. In addition to an overview of our approach to advancement of SOFC utilization, we intend to cover, as well, the availability of gas street components, system integration, safety, maintenance and product lifetime of proposed onboard fueling systems.