bluuebunny/crossref_metadata_2025 huggingface dataset:
Ni-Mo Porous Alloy Fabricated as Supporting Component for Metal-Supported Solid Oxide Fuel Cell and Cell Performance
Authors: Yang Sheng-Fu , Chuang Shie Zong Yang , Hwang Chang-Sing , Tsai Chun-Huang , Chang Chun-Liang , Huang Te-Jung , Lee Ruey-Yi
Published: February 2020

In this study, continuous manufacturing processes including spray drying, compression molding and sintering are developed and constructed to produce molybdenum (Mo)-containing nickel (Ni)-based porous alloy as a supporting component for metal-supported solid oxide fuel cell (SOFC). The porous interconnected networks of Ni-Mo alloy are made of introducing pyrolyzable filler during fabrication processes. The particle size distribution analysis results showed d50 of starting material (E.g., Ni, Mo, pyrolyzable filler and binder) after spray drying is 40.7 um. A compression load of 35 ton is applied to form a specimen with size of 60×60×1.2 mm and then sintered at 1200°C to obtain porous alloy. The anode (Ce0.55La0.45O2-δ -Ni, LDC-Ni), electrolyte (La0.8Sr0.2Ga0.8Mg0.2O3-δ, LSGM) and cathode (Sm0.5Sr0.5CoO3-
δ, SSC) is coated by using an atmospheric plasma spraying (APS) technique. The active electrode area of the cell is 16cm2 and the open circuit voltage (OCV) is higher than 1.0 V under cell performance testing from 600 to 750 °C, indicating that a fully dense layer of LSGM electrolyte is successfully fabricated via APS coating process. The measured maximum output power densities (@0.6V) of this cell have reached 1196, 1012, 716 and 415 mW/cm2 at 750, 700, 650 and 600 °C respectively, by employing H2 as fuel and air as oxidant.
Development of Toho Gas SOFC Cell Stack
Authors: Masuda Soichiro , Ogura Yusuke , Shimano Jun
Published: February 2020

Toho Gas has developed a planar type of scandia stabilized zirconia (ScSZ) electrolyte supported cell, and has been researching the improvement for the performance of cell stack.

We focused on the seal materials in order to improve the performance of Toho’s ScSZ electrolyte supported cell stack in this study. The existing seal material, powder type, is mixed with the organic solvent, and printed on the cell stack assembly. However, the seal quality varies in some degree in each samples, and the yield rate of printing process is not high enough. Furthermore, we have to design the cell stack with consideration for the seal contraction, because the seal materials crystallize and contract at the high temperature.

In this study, in order to improve the seal performance, we evaluate the seal performance of two types of seal, and the contraction thickness in some conditions.
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
Effect of LSCF Microstructure on GDC Interlayer Stability and Cation Diffusion in Porous and Dense LSCF/GDC/YSZ Triplets
Authors: De Vero Jeffrey , Bagarinao Katherine Develos- , Cho Do-Hyung , Kishimoto Haruo , Yamaji Katsuhiko , Yokokawa Harumi , Horita Teruhisa
Published: February 2020

The long-term stability of GDC interlayer as a reaction barrier between La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode and polycrystalline yttria-stabilized zirconia YSZ substrate is essential in improving the performance of the LSCF cathode at the required operating temperature. However, the formation of resistive phases, especially SrZrO3 at the interfaces that affects the performance of LSCF cathode is still difficult to mitigate even with the use of GDC interlayer. For this purpose, we systematically evaluated the long-term stability of GDC interlayer by performing cation diffusion experiments using porous and dense LSCF layers. The dense LSCF/GDC/poly-YSZ has homogeneous interfaces, enabling simpler analysis of interface stability and cation diffusion. In both heterostructures, a ~1.0 µm–thick, dense GDC interlayer was utilized which was prepared by PLD with subsequent annealing at 1300°C for 5h. The LSCF/GDC/YSZ heterostructures were then annealed in air at temperatures ranging from 800°C to 1000°C starting from 168 hours to 731 hours. We find that in porous LSCF, the GDC interlayer characterized by significant formation of pores while severe microcraking occurred in dense LSCF after prolonged annealing. We also observed shrinkage of GDC interlayer at elevated temperature in porous samples compared to dense. At high sintering temperature, the Sr and Zr diffusivity along the grain boundaries of GDC interlayer is the dominant diffusion pathway in porous LSCF/GDC/YSZ leading to the formation of SrZrO3, while for dense LSCF/GDC/YSZ, the cracks or crack–walls in the GDC interlayer are fast diffusion paths for cation diffusion. We also observed that the lateral growth of SrZrO3 at the GDC/YSZ interface is influenced by the microstructure of GDC interlayer and sintering temperature. Our results show that the interfacial microstructure of LSCF/GDC plays an important role in understanding the formation of SrZrO3 in LSCF/GDC/YSZ triplets as well as the effectiveness of GDC interlayer as a reaction barrier.
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.
Nickel Doped Lanthanum Chromite Perovskite: A Novel Regenerable Anode Material for Solid Oxide Fuel Cells
Authors: Sun Yi-Fei , Wang Meng-Ni , Luo Jing-Li
Published: February 2020

A series of nickel doped lanthanum strontium chromite (La0.7Sr0.3Cr1-xNixO3-y, x=0.05-0.3) perovskite anodes for SOFCs was fabricated by glycine combustion method. The structural properties and electrochemical performances of the anode materials were investigated. It was found that the materials with various nickel dopant content showed an orthorhombic perovskite phase. However the formation of parasitic phase of NiO could also be detected for the material with nickel content >20%. Thermogravimetric analysis (TGA) measurement performed in 5% H2-N2 showed that the mobility of oxygen in the materials increased with the increase of Ni content. For La0.7Sr0.3Cr0.8Ni0.2 (LSCNi) sample, Scan Electron Microscope (SEM) images detected the in-situ growth of nano Ni particles with the average diameter of 20 nm anchoring on surface of the material after the exposure in reducing atmosphere. The material with exsolution of Ni nano particle displayed improved power density output and reduced the activation polarization resistance compared to pure La0.7Sr0.3CrO3-y (LSC).

Figure 1
Visualization of SOFC Anode by Dual Imaging Method Using Infrared and Visible Light Cameras
Authors: Tachikawa Yuya , Kawabata Tsutomu , Shiratori Yusuke , Sasaki Kazunari
Published: February 2020

Thermography imaging can be applied for the surface of a SOFC electrode to evaluate the distribution of an electrochemical reaction during which either heat generation or absorption will take place. For getting a correct temperature distribution, change in emissivity of the object caused by chemical reactions or material coverage must be precisely evaluated. In-situ observation method using both infrared and visible light cameras, hereafter called dual imaging method, enables us to obtain a precise temperature distribution, because the influence of emissivity change can be eliminated by a visible light imaging technique. In this study, the dual imaging method was applied for an anode material which was exposed to a fuel flow prone to coke formation, and the information on the temperature distribution was successfully separated from the reflection of the coke deposited on the surface of anode to have a true temperature distribution.
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
Local Evolution of Three-Dimensional Microstructure Morphology of Planar Anode-Supported SOFC
Authors: Brus Grzegorz Adam , Iwai Hiroshi , Otani Yuki , Sciazko Anna , Saito Motohiro , Yoshida Hideo , Szmyd Janusz S.
Published: February 2020

In this research a planar anode-supported cell was tested over the period of 3700 hours. The investigated cell was tested as a part of six cells stack with standard power output 100 [W]. The aging test was conducted at 800oC and under constant current 19.4 A to provide 90 W of initial power output. After the operation subsequent post-test analysis of the selected cell microstructure has been conducted using combination of Focused Ion Beam and Scanning Electron Microscopy (FIB-SEM). Obtained data was reconstructed into 3D images, based on which the microstructure parameters were obtained. The microstructure parameters were quantified at three different location in the selected cell; inlet (downstream), middle and outlet (upstream). The obtained results indicate strong non-homogeneous microstructure morphology change after long-term operation.
Process Analysis for Achieving Highly Enhanced Total Efficiency on Multi-Stage Fuel Supplied SOFC System
Authors: Tachikawa Yuya , Matsuzaki Yoshio , Hatae Toru , Taniguchi Shunsuke , Sasaki Kazunari
Published: February 2020

Solid oxide fuel cells have a promising potential to realize a highly efficient energy conversion from chemical energy into electrical power. The system modification should be necessary for practical SOFC system to enhance its performance. We investigated a multi-stage fuel supply SOFC system which has additional fuel supply inlets between each SOFC stack. The anode offgas from the first stack is supplied to the next stack as reformed fuel gas being mixed with additional fresh fuel. In this study, the effect of the additional fuel flow ratio was evaluated to improve the electricity and heat output. In a two-stage SOFC stack case, by increasing the additional fuel supply ratio to the 2nd stack, total electrical output was almost the same, while it increased in the 2nd stack and it decreased in the 1st stack in which the system maintained thermally self-sustained operation. On the other hand, total heat output increased because the amount of vaporized water supplied to the system was decreased. Considering the results of this analysis, the multi-stage fuel supplied SOFC system can achieve higher energy conversion efficiency.
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
Effects of Copper Oxide Addition on the Electrochemical Properties of Samarium Doped Ceria Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells
Authors: Toor Sannan Yousaf , Croiset Eric
Published: February 2020

Low temperature sintering of samarium doped ceria (Sm0.2Ce0.8O1.9, SDC) can be required for metal-supported solid oxide fuel cells. Sintering aids (mostly transition metal oxides) can be used to substantially reduce the sintering temperature which also has an effect on the overall electrochemical process. 0-10 mol% of copper oxide and lithium oxide are added to the ceria solid solution through glycine nitrate combustion process and sintered at different temperatures ranging between 1000 and 1450°C. Hebb-Wagner polarization method and Electrochemical Impedance Spectroscopy (EIS) are used to separately characterize ionic conductivity, electronic conductivity and transference numbers. The results show that the 5% CuO/SDC sintered at 1100°C leads to similar total conductivity as pure SDC sintered at 1450°C, but the electronic conductivity decreases, which is expected to contribute to reducing the mixed ionic/electronic nature of the electrolyte.
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.
Solid Oxide Fuel Cell, Stack and System Development Status at Forschungszentrum Jülich
Authors: Blum Ludger , Batfalsky Peter , Fang Qingping , de Haart L.G.J. , Malzbender Jürgen , Margaritis Nikolaos , Menzler Norbert H. , Peters Roland
Published: February 2020

Based on more than 20 years SOFC scientific development, JÜLICH is still continuously improving its technology. Utilizing the proprietary cell manufacturing technology of warm pressing of the anode substrate cells of the dimension 20x20 cm² have been manufactured and tested in various stack sizes with power outputs of up to 5 kW, of which four were operated in a 20 kW system. It was demonstrated in a 1 kW stack that cells of this size can also be successfully operated using tape casted substrates. In parallel to the cell development the stack design was improved aiming at enhanced thermo-mechanical robustness. Thereby a stack in the kW range could be cycled successfully 100 times between 200 and 700°C. To be able to integrate also cells from other manufacturers the design was shifted to a picture frame layout, incorporating currently four 10x10 cm² cells in one layer, a larger number of cells is still optional. First successfully operated stacks showed a comparable performance to short stacks with one 10x10 cm² cell.

The 20 kW system set into operation in 2012 was operated for about 7000 h in total proofing thereby the suitability of the module and system concept developed in JÜLICH.

As special highlights, the long-term tests with short stacks have now reached under continuous operation at 700 °C and 0.5 Acm-² times of 63,000 h (degradation 0.7%/kh, 0.3%/kh in the last 25,000h) and 33,500 h (degradation 0.3%/kh), respectively.
Suppression of Carbon Deposition on Ni Films by Redox Treatment of Ceria Substrates
Authors: Wang Fangfang , Kishimoto Haruo , Bagarinao Katherine Develos- , Yamaji Katsuhiko , Horita Teruhisa , Yokokawa Harumi
Published: February 2020

For solid oxide fuel cells (SOFCs), ceria is very attractive material used as electrolyte or Ni-cermet. It possesses the fast oxygen transport due to its high concentration of oxygen vacancy under reducing atmosphere. In addition, it was reported that this oxygen vacancy defects can be rapidly formed and eliminated even at room temperature giving it a high oxygen storage capacity. However, it was not expected that the redox ceria can recovery completely after re-oxidized. Since it was reported that ceria can suppress the carbon deposition on Ni surface using Ni-cermet or Ni film supported on ceria, therefore, we want to clear whether or not this redox behavior play an positive role to suppress the carbon deposition on Ni film. In this work, we prepared Ni film with micrometer size on an as sintered Gd doped ceria (GDC) and GDC with redox treatment. We can reproduce the suppression of carbon deposition on Ni film using GDC with redox treatment as the substrate. However, this behavior disappears when as sintered GDC is used as the substrate. It seems that the GDC substrate after a single redox processing helps to suppress the carbon deposition on Ni film. Here, it is considered that large amount of oxygen vacancy and high concentration of electron in GDC after redox treatment play an important role to suppress the carbon deposition on Ni film for Ni/GDC.
Theoretical Analysis of Cation Diffusion Pathway in SOFC Interlayer
Authors: Lin Ching-Tang , Ishimoto Takayoshi , Koyama Michihisa
Published: February 2020

Cation diffusions in solid oxide fuel cell (SOFC) interface can cause some degradations. For instance, the effect that gadolinium-doped ceria (GDC) interlayer on the cathode prevent degradation of the SOFC cathode, and its degradation during current load cycling was investigated (1). Additionally, when  (LSCF) is used as cathode, Sr diffuses from the cathode to electrolyte through GDC interlayer and then insulating materials precipitates on the electrolyte. It is necessary to raise the temperature immediately or use large-scale experimental devices such as neutron diffraction device or accelerator (2) to trace cation diffusion pathway. By using molecular dynamics simulation (MD), diffusion pathway of oxygen ion is elucidated. However, in the time scale of MD simulation the structural and chemical transformations involving the breaking and formation of bonds are rare events (3). It is caused by the difference of jump probabilities. Thus, to accelerate the diffusion of cation, metadynamics method which adds history-dependent bias potential constructed by summing Gaussian-shaped is used (4). In this work, LSCF cathode, GDC interlayer and yttria stabilized zirconia (YSZ) electrolyte are modeled to simulate to trace cation diffusion pathway in SOFC interface.

References

M. Z. Khan, R. H. Song, S. B. Lee, J. W. Lee, T. H. Lim, S. J. Park, Int. J. Hydrogen Energy, 39,20799 (2014)

K. Fuzii, Y. Esaki, K. Omoto, M. Yashima, A. Hoshikawa, T. Ishigaki, J. R. Hester, Chem. Mater., 26, 2488(2014)

J. Kiss, T. Gruhn, G. Roma, C. Felser, J. Phys. Chem. C, 117, 25933 (2013)

U. Aschauer, P. Bowen, S. C. Parker, Acta Materialia, 57, 4765 (2009)
LSGM-based Cells for IT-SOFC Applications
Authors: Mercadelli Elisa , Sanson Alessandra , Gondolini Angela , Pinasco Paola , Basoli Francesco , Di Bartolomeo Elisabetta
Published: February 2020

Solid Oxide Fuel Cells have still many technical problems related to its high operating temperature (800–1000 °C). The most recent studies deal with reducing the operation temperature increasing at the same time the durability of the device. The use of La0.8Sr0.2Ga0.8Mg0.2O3-δ(LSGM) perovskite as electrolyte, could be a very promising solution for IT-SOFC operating at 600°C. In this work, LSGM bilayers constituted by a thicker porous layer (namely the anode scaffold) and a dense electrolyte were produce by co-firing using two different techniques: i) die-pressing + spin coating, ii) tape casting + lamination. In both cases the nature and amount of pore former needed to obtained an anode scaffold with a porous network suitable for the Ni impregnation process were deeply investigated.

In the die-pressing + spin coating method, supporting anodes were prepared pressing LSGM commercial powder with a proper amount of binder and a tailored mixture of pore forming agents. Onto the pre-sintered anode support, an electrolyte layer was deposited by spin coating. In the tape casting + lamination route, the starting ceramic suspensions with and without pore formers were carefully optimized to produce the anodic and electrolytic green tape respectively, while the lamination parameters, in terms of temperature, time and pressure, were adjusted to obtain defect-free bilayers. The sintering conditions were also optimized in order to achieve the best compromise in terms of density of the electrolyte and porosity of the anode scaffold.

Structural and morphological characterizations of the produced bilayers as well as the electrochemical performances of the cells in the temperature range 600-750°C will be reported. The potentialities and disadvantages of the two processing approaches will be thoroughly discussed.
Methane Synthesis Characteristics of H2O/CO2 Co-Electrolysis in Tubular Solid Oxide Electrolysis Cells
Authors: Luo Yu , Li Wenying , Shi Yixiang , Ye Xiaofeng , Wang Shaorong , Cai Ningsheng
Published: February 2020

Producing methane by H2O/CO2 co-electrolysis through solid oxide electrolysis cell (SOEC) is a promising method to store unstable renewable power and reduce CO2 emission simultaneously. Theoretically, methanation reaction is possible to happen in standard condition when temperature is lower than 600oC. Tubular solid oxide electrolysis cell (TSOEC) has great potential for large-scale application due to easily sealing and high strength. Moreover, gradient distribution of temperature in flow direction is beneficial to CH4 production. In this paper, CH4 synthesis characteristics in TSOEC is studied in the temperature range of 500-650oC by combining experiment and simulation. Experiment demonstrates the addition of H2 increases the outlet molar fraction of CH4 from 0 to 2.85% at 600oC, and from 0.01% to 8.77% at 550oC. In addition, it’s found that electricity significantly promotes CH4 production, especially when H2 is added. The applied voltage of 1.5V just increases CH4 production ratio by <0.04% in the absence of H2. But when 20% H2 is fed in cathode, CH4 production ratio is improved by 3-4%. Finally, the optimal operating condition, thermal distribution and reaction active zones are simulated by a well validated thermal model. The thermal distribution can be changed by outer boundary condition. CH4production can be further improved by increasing the temperature of upstream zone and reducing that of downstream zone.

Fig.1 
Methane synthesis schematic in TSOEC

Figure 1
Characterisation and Electrochemical Properties of Ce0.8Sr0.2Fe0.9Ir0.04Co0.06 (CSFIC) Cathode Material for Application in Low Temperature SOFC
Authors: Njoku Chima , Omondi B O , Ndungu Patrick
Published: February 2020

Abstract

In this study, the cathode Ce0.8Sr0.2Fe0.9Ir0.04Co0.06perovskite material was prepared by sol-gel technique and then tested for its characteristic application in solid oxide fuel cell. The textural properties were tested using X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy. The morphology was examined using scanning electron microscopy and high resolution transmission electron microscopy. The electrochemical properties were measured using Kittec Squadro muffle furnace from Fiaxell SOFC technologies connected to a Nuvant TM potentiostat and galvanostat. These properties were tested for its potential application in low temperature solid oxide fuel cells within 300 -500 °C. It exhibited a current density of 801.90 mA/cm2, a power density of 471.59 mW/cm2 and an area specific resistance (ASR) of 0.349 Ω/cm2.
Preparation and Characterization of LSC Cathode Current Collecting-Flow Channel Layer for SOFC
Authors: Hao Wu
Published: February 2020

La0.6Sr0.4CoO3 (LSC) powder synthesis by Sol-gel process, together with the appropriate proportion of dispersants, binders, plasticizers, solvents and sintering aids, after thoroughly mixed, tape casting,and laminated to obtain the desired thickness. Then flow channel layer according to the design of the plain mesoderm laser cutting, the cathode current collector can be obtained LSC actually used - flow channel layer, as shown in Fig 1.

Figure 1
Electrochemical Characterization of Ag-Y0.5Bi1.5O3 Composite Cathode on 8YSZ-Ce0.78Gd0.2Sr0.02O2-δ Electrolyte Using AC Impedance Spectroscopy
Authors: Hua Ching-Han , Chou Chen-Chia
Published: February 2020

The electrochemical performance of Ag-Y0.5Bi1.5O3 (YSB) cathodes on Ce0.78Gd0.2Sr0.02O2-δ (GDCS) electrolyte with an epitaxial Y0.16Zr0.84O1.92 (8YSZ) thin film outer layer was estimated using electrochemical impedance spectroscopy (EIS). A series of bismuth oxides with different silver contents were prepared and measured by an impedance spectroscopy on symmetrical cells in the temperature range from 500 °C to 650 °C. The microstructural analyses of porous composite cathodes and bi-layer electrolyte with fluorite structures were investigated by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that silver in the cathode reduces the surface resistance which improves the efficiency of current collection from the cathode. Besides, the bi-layer electrolytes have lower activation energy than GDCS electrolytes. Without topping Pt or silver metallic working electrode, the 50-70 vol% of Ag powder mixed with a submicron size YSB powder exhibited much lower overpotential and higher exchange current density than Lanthanum Strontium Cobalt Ferrite perovskite cathodes below 650 °C.
Role of Hole Doping on the Oxygen Vacancy Formation and Migration in LaCoO3
Authors: Salawu Omotayo akande , Gan Liyong , Schwingenschlogl Udo
Published: February 2020

The LaCoO3 class of materials is of interest for cathodes of solid oxide fuel cells. Spin-polarized

density functional theory is applied to cubic La0.75 (Mg/Ca/Ba)0.25 CoO3 . The effect of this cation

doping on the electronic and magnetic properties as well as oxygen vacancy formation energy is

studied. Oxygen vacancies with proximity to the dopant are energetically favourable in most cases.

We discuss the effect of distortions of the CoO6 octahedron on the electronic structure and the

formation energy of oxygen vacancies. The order of formation oxygen is found to be Mg > Ca >

Ba. Cation doping incorporates holes to the Co-O network which enhances the oxygen vacancy and migration.
Performance and Stability of La2NiO4+X As Air Electrode of Solid Oxide Electrolysis Cell
Authors: Kim Sun Jae , Choi Gyeong Man
Published: February 2020

Solid oxide electrolysis cell (SOEC) is regarded as one of the most promising hydrogen generation devices. However, electrolysis operated at high temperature has some problems; component inter-diffusion and difficulty in the selection of sealant etc.. SOEC (IT-SOEC) at intermediate temperature (550~650oC) may reduce problems, however, most of the overpotential occurs in air electrode. In this study, we have tested La2NiO4+δ (LNO) as an air electrode and compared the performance with that of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) which shows degradation due to Sr segregation. LNO has advantages due to its good thermal-expansion coefficient (TEC) match with electrolyte and little cation segregation. Electrochemical performance of SOEC at 650oC under electrolysis current shows that LNO is a promising as an air electrode.