bluuebunny/crossref_metadata_2025_split huggingface dataset:
Integrated Air Preheater and Anode Off-Gas Oxidizer
Authors: De Vos Yves , Janssens Jean-Paul 
Published: February 2020

The performance of a cathode air preheater with internal off-gas oxidation is presented. This component is a plate heat exchanger, handling both injection and oxidation of depleted anode gas in the hot cathode flow. The gas mixture oxidizes in the heat exchanger, and the reaction heat is used to preheat cathode air.
An initial integration effort using two separate components is reported. The system consists of a close-coupled injector and a downstream plate heat exchanger, which was catalytically coated. The performance was constrained by reaction kinetics: measurements showed that the off-gas and cathode mixture typically ignited within 5 – 10 ms at mixture temperatures above 750°C.
CFD on this system shows that part of the mixture takes more than 15 ms before reaching the inlet port of the heat exchanger, leading to early ignition. Both CFD and SEM analysis showed that the walls of the heat exchanger overheat to 1000 – 1100 °C. The SEM analysis reveal the effect of this overheating on scale growth and evaporation of Cr VI in the heat exchanger, and its subsequent condensation on the cool, catalytically coated walls.
The integrated HEX and oxidizer consists of an internal injector, which delivers the anode gas to each cathode flow path between pairs of heat exchanging plates. The injection occurs adjacent to a catalytically coated zone in the heat exchanger. The CFD effort covers the combined effects of injection, mixing, generation of reaction heat and heat exchange. The results show that the injection and subsequent mixing is uniform. The mixture reaches the cooled sections of the heat exchanger within 3 ms, and thus below the auto ignition time. These calculations are in line with experimental performance data on the integrated component.

Figure 1
A Parametric Study of SOFC Performances with Multi-Stage Electrochemical Oxidation for Enhancement of Electric Efficiency
Authors: Matsuzaki Yoshio , Tachikawa Yuya , Hatae Toru , Matsumoto Hiroshige , Taniguchi Shunsuke , Sasaki Kazunari 
Published: February 2020

The solid-state ceramic construction of SOFCs enables high fuel to electricity conversion efficiencies as high as 50 to 60 percent LHV with high temperature operation, allows more flexibility in fuel choice. Preceding studies have been reported on multi-stage electrochemical oxidation with SOFCs for further improvement of the electric efficiencies. However there are many parameters for the multi-stage oxidation, and effects of the parameters on the efficiency remains to be identified.
In this study, we have conducted a parametric study of SOFC performances with multi-stage electrochemical oxidation by using a symbolic analysis method developed for the parametric analysis to investigate the possibility of enhancement of the electric efficiencies. In the case of two-stage oxidation, the parameters having important impacts on the efficiency are found to be ratio of active electrode area of a first stack to a second stack, and net fuel utilization which should be decided by the ratio and the fuel utilization limit of the each stack.
This research is supported by The Japan Science and Technology Agency (JST) through its COI Program.
Protective Coatings for Metallic Components in Solid Oxide Fuel Cell Systems
Authors: Kidner Neil J , Ibanez Sergio , Arkenberg Gene , Seabaugh Matthew M , Swartz Scott L 
Published: February 2020

To make solid-oxide fuel cell (SOFC) systems more manufacturable and reduce system costs, SOFC developers, wherever possible, have substituted lower cost stainless steel into the stack design, including replacing ceramic interconnects within the stack and high-cost nickel-based superalloys in balance-of-plant components. However, for successful implementation of these steels, protective coatings are necessary to protect the air-facing metal surfaces from high temperature oxidation and to minimize chromium volatilization from the metal, because chromium volatiles poison the cathode and degrade cell performance.
NexTech Materials has developed a cost-effective coating technology to improve the high temperature performance of stainless steel components. Coatings include an electrically conductive, manganese cobaltite (MCO) coating tailored for the cathode active-area of metallic interconnects and a complementary diffusion-based aluminide coating for the non-active, seal-area of interconnects and also readily amenable to balance of plant components.
In this paper, the suitability of this coating technology for SOFC applications will be demonstrated. Microstructural analysis in combination with long-term electrical area-specific resistance (ASR), oxidation and chromium volatility testing will illustrate the stability and functionality of the coatings under application specific conditions. Stack-level testing will demonstrate the successful scale-up of the technology.
Electrochemical and Catalytic Behavior of Ni-Based Cermet Anode for Ammonia-Fueled SOFCs
Authors: Molouk Ahmed Fathi Salem , Yang Jun , Okanishi Takeou , Muroyama Hiroki , Matsui Toshiaki , Eguchi Koichi 
Published: February 2020

Solid oxide fuel cells (SOFCs) are one of the promising power generation devices due to their high energy conversion efficiency and low emissions. Hydrogen fuel can be used as an environmentally clean energy carrier for SOFCs. However, the storage and transportation are major obstacles for the large-scale application because of the low volumetric density and boiling point. Thus, high fuel flexibility of SOFCs has attracted much attention for a simplified power generation system.
Recently, ammonia was considered as a promising fuel for SOFCs because of following reasons; high energy density, ease in liquefaction (–33.4ºC at atmospheric pressure or 8.46 atm at 20ºC), no greenhouse gas emission, narrower flammable range than hydrogen. Much effort has been devoted to enhance the performance of direct ammonia fuelled SOFCs employing oxide-ion [1, 2] or proton [3, 4] conducting electrolytes. Meng et al. [2] fabricated a 10-μm thick SDC electrolyte with 50wt% Ni–SDC as an anode and BSCF as a cathode. A peak power density of 1190 mW/cm2 was achieved at 700 °C, which was the highest performance reported in literatures for the direct NH3-SOFC using oxygen ion conducting electrolyte.
In this report, the mechanism of electro-oxidation of ammonia over Ni-based cermet anode was studied. Especially, we focused on the correlation between the catalytic activity of anode for ammonia decomposition and cell performance. This systematic investigation has revealed that ammonia is catalytically decomposed to H2 and N2, and then H2 produced is electrochemically oxidized over anode. Furthermore, the operating temperature and hydrogen concentration had a great impact on ammonia decomposition as well as cell performance. These results provided the strategy for the development of anode materials for direct ammonia-fueled SOFCs.
[1] Qianli Ma, Jianjun Ma, Sa Zhou, Ruiqiang Yan, Jianfeng Gao, Guangyao Meng, Journal of Power
Sources 164 (2007) 86–89.
[2] Guangyao Meng, Cairong Jiang, Jianjun Ma, Qianli Ma, Xingqin Liu, Journal of Power Sources

173(2007) 189–193.
[3] N. Maffeia, L. Pelletierb, J.P. Charlandb, A. McFarlanb, Journal of Power Sources 140 (2005)
264–267.
[4] N. Maffei, L. Pelletier, J.P. Charland , A. McFarlan, Journal of Power Sources 162(2006) 165–167.
Performance Optimization of Cermet SOFC Anodes: An Evaluation of Nanostructured NiO
Authors: Burmistrov Ilya , Agarkov Dmitrii , Tartakovskii Ilya , Kharton Vladislav , Bredikhin Sergey 
Published: February 2020

Anode cermets of metallic Ni and stabilized zirconia are among the most common SOFC materials. The electrochemical performance of the composite anodes is essentially governed by the triple phase boundary formed by electronic conductor, solid electrolyte and gaseous phase. One important approach to optimize the anode morphology relates to decreasing particle size of the initial powders. On the other hand, a drastic reduction of the component particle size may lead to dramatic changes in the material properties. The tendencies to agglomeration, a presence of modified surface layers and fast rates of microstructural alterations under SOFC operating conditions are all expected to considerably affect the electrode preparation procedure and anode behavior.
The present work is centered on the analysis of key relationships between the morphology of initial NiO powders used to form Ni-containing cermets and overall quality of the composite SOFC anodes. The commercial Nickel (II) oxide nanopowder (99.8% purity, Sigma-Aldrich) was employed as a model starting material for these studies.
A large series of NiO powders were prepared by annealing of initial NiO at different temperatures (RT-1100 oC). Scanning and transmission microscopy, X-ray diffraction, thermogravimetry, X-ray photoelectron and Raman spectroscopic analyses were employed for morphological, chemical and structural characterization. Then the powders were mixed with highly dispersed solid electrolyte of 10 mol.% Sc2O3 and 1% mol.% CeO2 stabilized zirconia (10Sc1CeSZ) and an organic solvent to obtain screen-printable pastes, used to deposit anode layers onto 10 mol.% Sc2O3 and 1% mol.% Y2O3 stabilized ZrO2 membranes for further microstructural and electrochemical studies. The results showed, in particular, that starting NiO nanopowder (Fig. 1) possesses a core-shell structure, with the crystalline core covered by amorphous shell rich of excessive oxygen and adsorbed water. These surface layers, having critical impact on the integrity and performance of resultant anodes, can be eliminated by thermal pre-treatment.
Fig. 1. TEM image of starting NiO powder.

Figure 1
Oxidation-Induced Degradation of SOFC Ni Anodes at High Fuel Utilizations
Authors: Kawasaki Tatsuya , Sugimoto Junki , Tachikawa Yuya , Shiratori Yusuke , Taniguchi Shunsuke , Sasaki Kazunari 
Published: February 2020

In the downstream of SOFC systems, higher oxygen partial pressure may cause oxidation-induced Ni anode degradation, associated with the formation of NiO and/or Ni(OH)2. Under experimental conditions for Ni anodes exposing to high oxygen partial pressures, conduction pathways could be destroyed resulting in cell performance degradation. This study is therefore focusing on the changes in microstructure and cell performance at high fuel utilizations. The objective of this study is to derive guidelines for high fuel utilization operation towards higher power generation efficiency.
The cells used consist of Ni-based anode with scandia-stabilized zirconia (ScSZ), ScSZ electrolyte, and lanthanum-strontium-manganite(LSM)-ScSZ cathode. The electrochemical properties of the cells were measured at 800oC by feeding humidified fuel, H2 (20cc/min)-H2O (80cc/min), to the anode, and air (150cc/min) to the cathode. The condition for Ni oxidation was estimated by thermochemical equilibrium calculation software, HSC Chemistry. Performance stability was examined at a constant cell voltage for a constant partial oxygen pressure at the anode for 100h. I-V characteristics before and after the 100h test were measured and focused-ion-beam-scanning electron microscopy (FIB-SEM), and SEM-energy dispersive X-ray spectroscopy (SEM-EDX) analysis were conducted for microstructural characterizations.
Anode voltage threshold was derived from the oxygen partial pressure at the boundary where both Ni and NiO coexist in the phase stability diagram. The threshold voltage was 0.701 V at 800oC. The performance stability was examined for 100h at the constant cell voltage of 0.6 V, showing stable performance as shown in Image1. The resistances did not change before and after the test, and no microstructural change of the anode was observed. The performance stability was also examined at the constant cell voltage of 0.5 V in order to set the experimental condition near the threshold. As shown in Image 2, anode voltage started to vibrate during the test. The anode-side ohmic resistance increased during the vibration, suggesting Ni oxidation. But the electrochemical measurements revealed no change in anode resistances, indicating that the oxidation of Ni is limited to their surfaces. While slight agglomeration of Ni particles was observed, the number of isolated Ni particles was still small judging from FIB-SEM reconstruction images, maintaining their conduction pathways.

Figure 1
Highly Efficient and Redox Stable Layered Perovskite Ceramic Anode for Hydrocarbon Solid Oxide Fuel Cell
Authors: Sengodan Sivaprakash , Choi Sihyuk , Jun Areum , Ju Young-Wan , Shin Jeeyoung , Kim Guntae 
Published: February 2020

Perovskite oxides with variable oxygen non-stoichiometry play a prominent role in many fields, including fuel cells, catalysis and gas storage. One interesting class of materials for solid oxide fuel cells (SOFCs) are cation ordered layered perovskite oxides due to their mixed ionic and electronic conductivity and fast oxygen kinetics. Even though progress has been made in cathode materials to lower the cathodic polarization, still it is also important for fuel cell technology to achieve efficient anode that meets the requirements for long term stability with enhanced tolerance to carbon buildup (coking) and sulfur contamination (poisoning) from hydrocarbon fuels. Here, we report identification of cation ordered layered perovskite oxide, PrBaMn2O5+δ
redox-stable anode, with superior electrochemical performance in both hydrogen and hydrocarbons. Cation ordered PrBaMn2O5+δ
are fabricated by the in-situ annealing of disordered Pr0.5Ba0.5MnO3-δ
in reducing atmosphere directly from the fuel cell support. Our anode material shows high electrical conductivity of 8.16 S cm-1 in 5% H2 at 800 oC and demonstrates a peak power density ~1.3 Wcm-2 at 850 oC using propane as fuel.
Methodology for Analysis of Solid Oxide Cells via Raman Spectroscopy
Authors: Manerova Jevgenija , Call Ann V , Sinclair Derek C , Elder Rachael H 
Published: February 2020

Solid oxide cells (SOCs) are highly efficient electrochemical energy conversion devices capable of operating in both fuel cell and electrolysis modes. The operating temperatures of SOCs (500 – 800 oC, for IT-SOCs) create opportunities for direct utilisation of a wide variety of reactants, including low-grade fuels such as biogas, however, in-situ characterisation of evolving electrode morphologies and compositions is challenging. Conventional in-situ characterisation techniques, including impedance spectroscopy, can provide valuable information about electrochemical processes, but are unable to resolve specific chemical and physical changes during cell operation which can adversely affect SOC performance. Raman spectroscopy is a valuable analytical tool for in-operando monitoring of SOCs. Molecular species adsorbed on the surface can be identified, thus providing direct insight into reaction intermediates, material phase transformations and the presence of contaminants and poisons, such as carbon, chromium, sulfur and silica. Raman spectroscopy is a versatile technique that can be used for temperature sensing, semi-quantitative estimation of infiltrated material and many other applications. The design of optically accessible experimental setup will be presented alongside methodology for obtaining and interpreting in-situ Raman spectroscopic measurements. Raman spectroscopic evidence of carbon deposition during CO2 electrolysis will be discussed.
Impedance Studies of the Reduction Process in NiO-YSZ SOFC Anodes
Authors: Vladikova Daria , Stoynov Zdravko , Wuillemin Zacharie , Montinaro Dario , Piccardo Paolo , Genov Ivaylo , Rolland Mélanie 
Published: February 2020

The optimization of Ni-YSZ anodes is an important step in obtaining electrically efficient anode supported SOFCs. Despite the continuous studies concerning optimization of the anode reduction conditions, degradation phenomena, oxidation-reduction cycling behaviour and microstructural changes, the anode reduction continues to be an active field for deeper insight [1,2], since as a final stage of the cell preparation, it offers an opportunity for optimization in respect to mechanical stability, electronic conductivity, catalytic activity and gas permeation. This is additionally complicated due to the counter-flow of the fuel and exhaust water vapour.
This study combines two approaches – impedance spectroscopy and gas permeability studies that ensure experimental information about the main processes occurring during anode reduction: (i) formation of a new microstructure influencing the diffusive mass transfer and (ii) development of an electrically conductive network. The gas permeability studies [3] are carried out on anode pellets at room temperature before and after reduction performed at different conditions (temperature, reduction atmosphere). The observed changes are discussed and compared with SEM microstructural analysis. The impedance measurements are carried out directly during the reduction of button cells, segmented cells and NiO-YSZ anode pellets and thus the reduction process is studied during its evolution. The influence of the reduction conditions, including the duration of the process, is discussed in respect to the formation of an optimal Ni network with good electrical connectivity and catalytic activity.
The presented figure shows two impedance diagrams measured on a segment from segmented fuel cell in different stages of the reduction process .

Acknowledgement:The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) Fuel Cells and Hydrogen Joint Undertaking (FCH-JU-2013-1) under grant agreement No 621207.
References

S.-W. Baek, J. Bae, Internat. J. Hydrogen energy 36 (2011) 689

B. Liu, Y. Zhang, B. Tu, Y. Dong, M. Cheng, J. Power Sources 165 (2007) 14

E. Mladenova, D. Vladikova, Z. Stoynov, A. Chesnaud, A. Thorel, M. Krapchanska, Bulg. Chem. Communic. 3 (2013) 366

Figure 1
La, Y and Nb Doped SrTiO3 Anodes for Electrolyte Supported SOFC
Authors: Tiwari Pankaj Kr , Basu Suddhasatwa 
Published: February 2020

Bi-doped materials, La, Y and Nb, present at both A and B sites of SrTiO3 have been synthesized and tested as anode material for SOFC. The cell performance of bi-doped anode material e.g., LYST and LNST found to be higher than single-doped anode e.g., LST and NST. 20 wt % Ni-YSZ addition to LYST and LNST increased the cell performance from 23 mW/cm2 to 77 mW/cm2 and 25 mW/cm2 to 38 mW/cm2, respectively. LYST-Ni-YSZ anode gave the maximum power density 70 mW/cm2, which is stable for 60 h of operation as shown in fig.1. Physical characterizations e.g., SEM, XRD and TEM of anode materials were investigated to correlate performance of different anodes.

References

[1] M.C.Verbraeken, B.Iwanschitz, A.Mai, J.T.S.Irvine, J. of the Electrochemical Soc. 2012;
159(11):F757.
[2] P.Puengjinda, H.Muroyama, T.Matsui, K.Eguchi, J. of Power Source 2012;204; 67.
[3] T.Ikebe, H.Muroyama, T.Matsui, K.Eguchi, J. of the Electrochemical Soc. 2010;157(6):B970.

Key words: Bi-doped SrTiO3, SOFC, electrolyte supported

Figure 1
Cell Performance of Anode-Supported BaZr0.85Y0.15O3-δ/Carbonate Composite Electrolyte at Intermediate Temperature
Authors: Kim Ji-Tae , Park Ka-Young , Park Jun-Young 
Published: February 2020

Recently, proton-conducting based-protonic ceramic fuel cells (PCFCs) have received great attentions as sustainable power generators at the intermediate temperature, because of their higher ionic conductivity with lower activation energy as compared to the oxygen-ion-conducting electrolytes based solid oxide fuel cells (SOFCs). Among several perovskite-type proton conducting oxides, yttrium-doped BaZrO3 (BZY) have exhibited considerable bulk proton conductivity with a high chemical resistance against CO2 and H2O in the intermediate temperature range. However, the manufacturing of porous electrode-supported dense BZY electrolyte cells virtually needs awfully difficult processes by the current SOFC technology due to its poor sinterability. Furthermore, high sintering temperature results in decreasing the proton conductivity of BZY with the BaO sublimation and low-conducting Y2O3-like phase formation. In addition, the BZY materials are still required to improve proton conductivity under the PCFC operating condition.
To achieve these goals, we have designed two-phase composite electrolytes consisting of a BZY matrix phase and a binary eutectic carbonate (Li–0.5Na)2CO3 phase in previous works. The conductivity of the composite electrolytes is higher than that of the BZY under the PCFC operating condition. Moreover, dense BZY composite electrolytes are fabricated with a carbonate phase at a remarkably low sintering temperature of 670 °C. Hence, in this work, anode-supported BZY/carbonate electrolyte cells are fabricated by the co-pressing technique with the Ni-cermet anode and as lithiated NiO cathode to confirm this composite electrolyte concept and then co-sintered at 600°C for 1 h. For the physicochemical and electrochemical characterizations, the anode-supported composite PCFCs are investigated by various analysis tools such as XRD, SEM, electrochemical polarization, and impedance spectroscopy.
[1] K.D. Kreuer, Annu. Rev. Mater. Res. 33 (2003) 333–359.
[2] E. Fabbri, D. Pergolesi, E. Traversa, Chem. Soc. Rev. 39 (2010) 4355-4369.
[3] E. Fabbri, L. Bi, D. Pergolesi, E. Traversa, Adv. Mater. 18 (2012) 195-208.
[4] T. Schober, H.G. Bohn, Solid State Ionics 127 (2000) 351–360.
[5] K.-Y. Park, T.-H. Lee, J.-T. Kim, N. Lee, Y. Seo, S.-J Song, J.-Y. Park, J. Alloys Comp. 585 (2014) 103–110.

Keywords: Protonic ceramic fuel cell (PCFC), Composite electrolyte, Yttrium-doped barium zirconate (BZY), Carbonate, Performance.

* Corresponding authors: jyoung@sejong.ac.kr (J.-Y. Park).
Status of Solid Oxide Fuel Cell Development at Elcogen
Authors: Noponen Matti , Torri Pauli , Göös Jukka , Chade Daniel , Hallanoro Paul , Temmo Aleksander , Koit Andre , Ounpuu Enn 
Published: February 2020

Elcogen is a manufacturer of solid oxide fuel cell (SOFC) unit cells and stacks. The competitive advantage of Elcogen products is their performance characteristics at reduced temperatures. The unit cell structure is optimized for operating temperatures 600 – 700°C and is made of a material system from anode to cathode of NiO/YSZ – YSZ – GDC – LSC. Elcogen tailors the unit cells with different thicknesses and shapes according to the customer requirements. Elcogen stacks are optimized for stationary applications in which both the operation temperature and pressure drop can be reduced due to stack characteristics enabling cost savings because of reduced material costs both in stack and system level, and increased system efficiencies due to reduced air compression losses and enhanced Nernst potential.
The article describes the performance characteristics of Elcogen unit cells and stacks. As an example, the area specific resistance of the unit cells has been determined to be 0.17 Ω.cm2 at 700°C, U
fuel = U
air = 20%, and the degradation rate below 5 mΩ.cm2.kh-1 in 10,000 hours test. The average stack voltage is measured to be 0.97V at 30A, T
ave = 700°C, and V
air = 2.2 and V
H2 = 1.0 lN/min/cell. The pressure drop for the air and fuel at the same conditions is less than 5mbar. With the encoring technical results and customer feedback, Elcogen is constantly increasing its unit cell and stack production capacity.