bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication and Performance of Ceramic Anode-Supported Solid Oxide Fuel Cells
Authors: Yang Zhibin , Pang Zhaohua , Zhu Tenglong , Zheng Ziwei , Han Minfang
Published: October 2013

Solid oxide fuel cell (SOFC) has been considered as one of the promising power generation technologies for its high efficiency and fuel flexibility. Therein, anode supported SOFC with thin Gd0.1Ce0.9O2-δ (GDC) electrolytes have been shown to exhibit high performance in low temperature. Sr2Fe1.5Mo0.5O6-δ (SFM) ceramic anode materials have been studied due to its high carbon deposition resistance. Therefore, fabrication and performance of SFM-GDC(50:50 mass%) anode supported button cell with GDC electrolyte were researched in this work. The single cell performance was characterized with Ba0.9Co0.7Fe0.2Nb0.1O3-δ cathode. The maximum power density reached 188 mW cm-2 at 700 oC, without use of any metal catalyst to enhance the electro-catalytic. The big ohmic resistance resulting from low electronic conductivity of SFM-GDC supporter limits power output of the cell. The future work will be focused upon the ratio of SFM and GDC anode supports.
Intelligent Analysis for Evaluating Physical Degradation Using Acoustic Emission
Authors: Fukui Ken-ichi , Sato Kazuhisa , Hashida Toshiyuki , Mizusaki Junichiro , Numao Masayuki
Published: October 2013

We previously developed a technique by which to measure the mechanical damage of SOFC using the acoustic emission (AE) method. In the present paper, we applied an adapted Self-Organizing Map (SOM), which is an artificial neural network model, to produce a cluster map reflecting the similarity of AE events. The obtained map visualized the change in occurrence patterns of similar AE events, revealing six phases of damage progress. Moreover, we inferred mechanical interactions among components of SOFC from a series of AE events by our proposed data mining method called co-occurring cluster mining. Our methods provide a common foundation for a comprehensive damage evaluation system and a damage monitoring system.
Surface Segregation and Chromium Deposition and Poisoning on La0.6Sr0.4Co0.2Fe0.8O3-
δ Cathodes of Solid Oxide Fuel Cells
Authors: Zhao Ling , Drennan John , Kong Chun , Amarasinghe Sudath , Jiang San Ping
Published: October 2013

La0.6Sr0.4Co0.2Fe0.8O3-
δ, (LSCF) perovskite oxide is one of the most common cathode materials used in solid oxide fuel cells (IT-SOFCs), but vulnerable to the chromium deposition and poisoning in the presence of gaseous chromium species from metallic interconnect. In this work, the fundamental relationship between the surface segregation and Cr deposition and poisoning of LSCF cathodes is studied on dense LSCF bar samples. The detailed SEM and FIB-EDS analysis results clearly indicate the segregation of strontium and cobalt, forming individual SrO and CoOx particles on the LSCF surface after annealing at 800 °C for 96 h. The results indicate that Cr deposition occurs preferentially on the segregated SrO particles on the LSCF surface.
Application of Low Temperature Ceramic Coating Process for SOFC Electrolyte and Electrode Fabrication
Authors: Choi Jong-Jin , Choi Joon-Hwan , Park Dong-Soo
Published: October 2013

Aerosol deposition, ceramic coating process by powder spray at room-temperature under low vacuum, is a promising process for preparation of SOFC cells and stacks’ component to minimize a detrimental reaction during cell production. Moreover, the process has flexibility of microstructure modification from gas-tight dense structure to porous structure with nano-scaled composites on various substrates including Ni-based cermet or even metal-support. In this study, we developed dense electrolyte coating of LSGM electrolyte on Ni-GDC, Ni, and Crofer22APU support, respectively, at room temperature, and achieved maximum power density of 1.31, 0.79, and 0.28 W/cm2 at 750oC, respectively. Nano-structured porous LSCF cathode were also prepared at room-temperature and polarization resistance of 0.11 Ω·cm2 was achieved.
Design and Fabrication of Electrolyte-Supported Tubular SOFC Combined with Supercritical Water Oxidation on Biomass Gas
Authors: Kim Hwan , Parfitt Andrew , Park Sung Tae , Chung Yong Sik , Chung Jong Shik , Sammes Nigel Mark
Published: October 2013

Solid oxide fuel cells (SOFCs) are relatively simple and environmental friendly devices for the production of electricity from hydrocarbons. The use of a high pressure supercritical water (SCW) reactor containing a SOFC has the potential for using a multitude of logistical liquid fuels that would otherwise not be possible in a regular SOFC system. A SOFC-SCW system was designed to allow the anode to be exposed to the pressure and chemical milieu of the supercritical water oxidation reactor. The effects of the amount of water/fuel and oxygen fed into the reactor under SCW conditions at 400°C were studied. The effects on electrochemical performance as well as preliminary results on a number of feed stocks, for example pectin, are also described.
Unconventional Approaches for the Production of Large Area SOFC
Authors: Sanson Alessandra , Mercadelli Elisa , Gondolini Angela , Pinasco Paola
Published: October 2013

Whereas significant advances have been reported in the performances of solid oxide fuel cells, some work has still to be done to reduce the costs connected to the overall processing of these systems. Tape casting and screen-printing are the most common techniques used for the fabrication of large area SOFCs. The production of the bilayer anode-electrolyte entirely by tape casting, or by tape casting coupled with screen-printing, are two of the most economical and reliable shaping alternatives. The work presents two unconventional approaches to these techniques applied to the production of anode-supported half-cell (NiOGDC/GDC), namely the use of water-based screen printing inks and an innovative lamination process done at room temperature and low pressure. These variations of the common multilayer production scheme, potentially allow overcoming two of the drawbacks connected with them: the use of organics for the production of screen printing inks and high temperature or glues for the lamination of tapes. Both approaches allowed producing crack-free large area half cells with dense GDC electrolyte.
Novel Co-Sintering Techniques for Fabricating Intermediate Temperature, Metal Supported Solid Oxide Fuel Cells (IT-m-SOFCs)
Authors: Rahul S H , Rupa Pantula K. P. , Panda Nirmal , Balasubramanian Krishnamurty , Kumar R. V. , Krishnan Venkatesan Venkata
Published: October 2013

Metal supported SOFCs (m-SOFCs) offer the advantages of inexpensive metal components as compared to the more expensive rare earth materials, since the entire ceramic support layer is replaced by ferritic steels, e.g., SS430L, AISI 441. However, with sintering conditions for ceramic and metalliclayers being different, it is difficult to sinter all the layers at one temperature to make a fuel cell. In this work, a triple layered structure comprising porous metal support (SS 430L), NiO + GDC (anode functional layer) and GDC (electrolyte) was co-sintered at 950°C, with superimposed high pressure (up to 180 bar, so far), with a soak time of 30 minutes at this temperature and pressure, to achieve densification and interlayer bonding. An additional step of using plasma to provide high heat flux to the electrolyte surface over a very short time provides a good surface finish by enhancing sintering. Both these methods have been applied for the first time for the combined sintering of multiple layers. Preliminary runs have been successful and the samples have been analyzed using SEM. Data from SEM show the onset of sintering at temperatures as low as 960ºC, at high pressures of up to 180 bar. Plasma ‘glazing’ experiments also demonstrate a temperature gradient of over 700°C across the fuel cell element, and clearly observed densification of NiO-GDC achieved over a 2 minute period of time.
Electrical Characterization of YSZ Thin Films Using a Calibrated Platinum Micro-Electrode
Authors: Georges Samuel , Bailly Nicolas , Djurado Elisabeth
Published: October 2013

A bulk platinum microelectrode calibration method, aiming at providing reliable measurements of the electrical properties of thin solid electrolyte films, is described. The method consists in the determination of the electrically active surface of an electrode of microscopic dimensions based on the confident measurement of the conductivity of a well know reference sample. The method is demonstrated to be efficient, reliable and reproducible in the case of yttria-stabilized zirconia films prepared by different techniques for films thicknesses ranging from 1.5 µm to 10 µm.
Improved Electrolyte Performance in Plasma Sprayed SOFCs by Electrode Modification
Authors: Marr Michael , Metcalfe Craig , Fan Eric Sheung-Chi , Kesler Olivera
Published: October 2013

Electrolytes were deposited by atmospheric suspension plasma spraying (SPS) in metal-supported SOFCs having both anode- and cathode-down configurations. The electrodes on the metal supports were intentionally made thin (< 30 μm) and smooth (average roughness < 2.5 μm) to reduce the formation of segmentation cracks and concentrated porosity in the electrolytes. In the anode-down cells, the electrolytes had minimal concentrated porosity and no segmentation cracks were observed. Open circuit voltages (OCVs) were above 1.05 V at 750 °C in cells with 21 μm thick electrolytes. The electrolytes in cathode-down cells had higher leak rates than those in the anode-down cells, and segmentation cracks were observed in some cathode-down cell electrolytes. The cathode-down cells having the most gas-tight electrolytes were electrochemically tested. OCVs were initially above 1.04 V, though performance declined significantly within 2-4 hours. In contrast, the OCVs of the anode-down cells were approximately constant after 12 hours of testing.
A Tri-Layer Proton-Conducting Electrolyte for Chemically Stable Operation in Solid Oxide Fuel Cells
Authors: Bi Lei , Traversa Enrico
Published: October 2013

Two BaZr0.7Pr0.1Y0.2O3-δ
(BZPY) layers were used to sandwich a BaCe0.8Y0.2O3-δ
(BCY) layer to produce a tri-layer electrolyte consisting of BZPY/BCY/BZPY. The BZPY layers significantly improved the chemical stability of the BCY electrolyte layer, which was not stable when tested alone, suggesting that the BZPY layer effectively protected the BCY layer from CO2 reaction, which is the major problem of BCY-based materials. A fuel cell with this sandwiched electrolyte supported on a Ni-based composite anode showed a reasonable cell performance, reaching 185 mW cm-2 at 700 oC, in spite of the relatively large electrolyte thickness (about 65 µm).
Fabrication of Low Ni-Containing SOFC Anode Using Mixed Ionic and Electronic Conductors
Authors: Kikuchi Ryuji , Minami Tatsushi , Takagaki Atsushi , Sugawara Takashi , Oyama Shigeo Ted
Published: October 2013

Typical anodes of solid oxide fuel cell consist of a cermet of electronic conductor such as Ni and oxygen ion conductor such as yttria-stabilized zirconia, and have porous structure to enlarge reaction sites. It has been recognized that volume expansion of the Ni species during redox cycle can damage the anode structure and that sintering of the Ni species results in degradation of power generation characteristics. One possible approach for lessening these undesirable effects is to reduce the amount of Ni in the anode, whereas reduced Ni amount in turn decreases the anodic reaction sites. In this study, Ni-SDC (samaria-doped ceria) cermet was prepared by changing SDC particle size and Ni content, and I-V and AC impedance measurement were conducted to evaluate the electrochemical processes that influence the performance of the anode by introducing ΔZ'spectra. It was found that large SDC particles were effective in reducing ohmic overpotential even with low Ni content, and that the conductivity change in the anode with Ni content can be explained by percolation theory.
Ni-Zr0.75Ce0.25O2-δ Composite as Steam Methane Reformable SOFC Anode
Authors: Biswas Snehashis , Das Sharma Abhijit , Buragohain Amlan , Stayanarayana Chilukuri V. , Basu Rajendra Nath
Published: October 2013

The feasibility of Ni supported Zr0.75Ce0.25O2-δ (ZCO) composites as steam methane reformable anode has been studied. ZCO powder was prepared by combustion synthesis technique using L-alanine as fuel. Phase pure material with average particle size below 1 µm was obtained upon calcination at 700oC for 6 h. Thermal expansion behaviour and electrical characterization of bulk samples of such Ni-ZCO composite anodes (Ni content between 20 and 40 vol%) have been carried out. Steam methane reforming (SMR) activity of the samples was also evaluated. The composite anodes were found to be quite promising in terms of matching thermal expansion coefficient, electrical conductivity and SMR activity. Anode supported single cells having configuration Ni-ZCO/YSZ/LSM have been fabricated and tested using methane as fuel.
Carbon-Resistant Micro Tubular SOFCs Fabricated by Co-Spinning Process Based on a Phase-Inversion Method
Authors: Meng Xiuxia , Gong Xun , Yang Naitao , Tan Xiaoyao , Yin Yimei , Ma Zi-Feng
Published: October 2013

The dual layer ceramic hollow fibers, such as YSZ/Ni-YSZ or Ni-YSZ/porous YSZ for the micro tubular solid oxide fuel cells were prepared by a co-spinning-sintering process. The cells from YSZ/Ni-YSZ dual layer hollow fiber show a high output power density using hydrogen as the fuel, but a short life time using methane as fuel due to carbon deposition. An improved Ni-YSZ/porous YSZ dual-layer hollow fiber is co-spun for carbon-resistant dual-composition anode. The micro tubular SOFC is fabricated by dip-coating a dense YSZ electrolyte membrane on the top Ni-YSZ layer, and impregnating Cu-CeO2, a carbon-resistant catalyst, into porous YSZ support. The fabricated micro tubular SOFCs with Ni-YSZ/Cu-CeO2-YSZ double anode show both a high power output and a good stability using the dry methane fuel. No carbon deposition is observed on the dual-layer anode.
Raman Spectroscopy Study of SOFC Electrode Surfaces
Authors: Li Xiaxi , Lee Jung-Pil , Blinn Kevin Scott , Park Soojin , Liu Meilin
Published: October 2013

Raman spectroscopy has been applied to probe and map surface species and incipient phases on the surfaces of electrodes in fuel cells, batteries, and supercapacitors under different conditions. In this presentation, we report our recent progress in the development of surface enhanced Raman spectroscopy (SERS) for enhancement of sensitivity to surface species and incipient phases on materials used in solid oxide fuel cells (SOFC). In particular, we demonstrated that SiO2 shell isolated Ag nanoparticles have excellent thermal robustness and chemical stability for SERS study of electrode materials at high temperatures, providing information vital to understanding the mechanisms of materials performance and degradation, thus offering critical insights for rational design of new materials with higher functionalities and performance.
Simulation of Solid Oxide Fuel Cell Anode Microstructure Evolution Using Phase Field Method
Authors: Jiao Zhenjun , Shikazono Naoki
Published: October 2013

A phase field method is used to simulate the microstructural evolution of nickel-yttria stabilized zirconia composite anode of solid oxide fuel cell based on three-dimensional microstructures reconstructed by focused ion beam-scanning-electron-microscopy technique. By implementing efficient semi-implicit Fourier spectral method in the phase field simulation with different periodic boundary conditions, the computation efficiency is improved in orders of magnitude. In order to quantitatively study the correlation between the anode microstructure evolution and the resulting electrochemical performance degradation, the evolution of three-phase boundary and nickel specific surface area are calculated. Degradation experiments have been conducted to evaluate the simulation results. By choosing an appropriate value for mobility in the simulation, predicted and experimental results showed good agreement.
Transmission Electron Microscopy Observation of Nickel-Yttria Stabilized Zirconia Catalyst for Solid Oxide Fuel Cells in Methane Atmosphere
Authors: Tokunaga Tomoharu , Tasugi Hiroki , Iwamoto Natsuki , Yamaguchi Toshiaki , Sumi Hirofumi , Fujishiro Yoshinobu , Sasaki Katsuhiro , Yamamoto Takahisa
Published: October 2013

Carbon growth site on the surface of a solid oxide fuel cell (SOFC) comprising yttria stabilized zirconia (YSZ) and Ni was observed using transmission electron microscopy (TEM). TEM observations of the YSZ and Ni powder mixture, which was heated in a methane atmosphere, confirmed that graphite was grown on the Ni surface only, and not deposited on the YSZ surface or the interface between YSZ and Ni. Additionally, the grown graphite was confirmed to have a curled structure and to terminate growth at the Ni-YSZ interface. These phenomena were likely caused by differences in the carbon wettability against Ni or YSZ, as well as oxygen diffusion from YSZ to Ni.
Preliminary Studies about Carbon Deposition Behavior of Ni-Metal/YSZ Bimetallic Cermet Anode of SOFC
Authors: Chung Yong Sik , Kim Hwan , Yoon Heechul , Chung Jong Shik , Sammes Nigel Mark
Published: October 2013

Nickel/Yttrium-stabilized zirconia (Ni/YSZ) composite is the standard anode material with high stability and catalytic activity in both oxidation of H2 and reforming hydrocarbons. However, carbon is deposited on the surface of Ni catalyst in hydrocarbon atmosphere which is called coking. It leads to decrease in percolation, power density, and eventually crack. In this paper, 5 mol% of titanium Oxide (TiO2) and manganese oxide (MnO) are added to NiO/YSZ powder. Prepared mixed anode powder is applied on Ni/YSZ support button cell as functional anode. Hydrogen oxidation catalytic activities of sample anodes were measured by IV curve, and polarization resistances were measured by impedance spectroscopy analysis at 800 ˚C in dry H2 atmosphere. Ni/YSZ, 5 mol% MnO Ni/YSZ and 5mol% TiO2 Ni/YSZ cells showed power density of 628mW/cm2, 458mW/cm2 and 382mW/cm2 at 0.6V respectively. Cells survived in dry CH4 atmosphere for 16, 27 and 32 minutes without performance drop.
Effect of Steam-to-Carbon Ratio on Degradation of Ni-YSZ Anode Supported Cells
Authors: Madi Hossein , Diethelm Stefan , Van herle Jan , Petigny Nathalie
Published: October 2013

Internal steam reforming (IR) of methane was investigated on Ni-YSZ anode supported cells, looking in particular at the effect of the steam to carbon (S/C) ratio on the degradation rate. The cells were fed with different H2O/CH4 mixtures during 100 hours sequences, alternating with sequences of dry H2 feeding. V-I characterization was performed before and after each sequence, and EIS measurements were performed regularly. A marked degradation was observed during the IR sequences while it was negligible under dry H2 feed. The observed degradation, attributed to carbon deposition on the anode active sites, was partially reversible for S/C >1.5, whereas it became irreversible at lower S/C.
Calculation of a Standard Reformed Biogas Composition and Testing on SOFC Anode Powders
Authors: Gamble Stephen , Neagu Dragos , Irvine John T. S.
Published: October 2013

A standard reformed biogas composition, based on a 63% CH4 37% CO2 input biogas, was defined by calculation. It is designed to resemble the composition of biogas that would enter a real SOFC stack, assuming 80% fuel utilization, and 25% recirculation of the anode off-gas. It is thermodynamically impervious to coking above 720°C. This gas composition was then used to test the catalytic reforming performance of nickel powder and La0.8Ce0.1Ni0.4Ti0.6O3-δ at 900°C in the standard reformed biogas. No coking was seen on the powder samples by visual inspection after this test. The La0.8Ce0.1Ni0.4Ti0.6O3-δ is designed to exsolve Ni nanoparticles when reduced. SEM pictures of the post-test sample show some small particles that may be exsolved nanoparticles, but further investigation is needed to confirm this. Ni powder was the better reforming catalyst, but sintered extensively in the 3 h test. The La0.8Ce0.1Ni0.4Ti0.6O3-δ also showed reforming capability, and much better microstructural stability in the standard reformed biogas.
XRD and Raman Spectroscopy Study of Mn Solubility in Cerium Oxide
Authors: Zhao Liang , Hyodo Junji , Ishihara Tatsumi , Sasaki Kazunari , Bishop Sean R.
Published: October 2013

The solubility of Mn in CeO2 was investigated for 3-50 mol% Mn. Powders were synthesized by the Pechini method in air. Raman spectroscopy and lattice parameter analysis revealed that the solubility limit of Mn in CeO2 is less than 3 mol% for the present preparation conditions. The low solubility limit was rationalized in terms of the much smaller ionic radius of Mn versus Ce. As a consequence, an approach to increase the Mn radii size through annealing in reducing conditions (humidified H2 at 1100 °C) was attempted. In this case, the MnO phase was observed by XRD, thereby indicating difficulty in obtaining Mn doped CeO2 under reducing conditions, as well.
Novel In-Situ Sintering Spinel Composite Cathodes for Metal Supported SOFCs
Authors: Dietzen Egle , Trofimenko Nikolai , Kusnezoff Mihails , Sauchuk Viktar , Belda Chriffe Omar , Michaelis Alexander
Published: October 2013

Metal-supported cells (MSC) for SOFC have attracted growing attention over the last decade, especially for portable and mobile applications. To avoid oxidation of the metal support, sintering steps are typically executed in inert or reducing atmosphere. Standard cathode materials, which are normally used for electrolyte-supported (ESC) or anode-supported (ASC) cells, decompose in such atmospheres. Therefore cathodes should be applied to metal-supported cells only after all the non-oxidizing-atmosphere processing steps are finished. Recently, we have developed new in-situ sintered composite cathodes with sintering temperature < 950 °C. Good adhesion as well as low and long-term stable polarization resistance of new electrodes has been obtained.
Influence of Donor Doping on Cathode Performance: (La,Sr)(Ti,Fe)O3-δ Case Study
Authors: Perry Nicola H. , Pergolesi Daniele , Sasaki Kazunari , Bishop Sean R. , Tuller Harry L.
Published: October 2013

Donor doping of the p-type solid oxide fuel cell cathode, Sr(Ti,Fe)O3-δ, with La was pursued to examine the role of minority charge carriers (electrons) on the oxygen exchange rate. Model dense thin film cathodes of (La,Sr)(Ti,Fe)O3-δ were fabricated by pulsed laser deposition. Optical transmission spectroscopy measurements demonstrated that the addition of the donor La resulted in a change in valence state of Fe from 4+ to 3+, suggesting a rise in Fermi level. The activation energy of the cathode’s area specific resistance, studied by impedance spectroscopy, was found to be lower with La addition; however, the magnitude of the area specific resistance was not lowered.
Electrochemical and Redox Studies of Sm0.5Sr0.5Co1-X
Nb
x
(x = 0, 0.1) as Cathode Materials in Intermediate Temperature-Solid Oxide Fuel Cells
Authors: Yoo Seonyoung , Jun Areum , Shin Jeeyoung , Kim Guntae
Published: October 2013

The perovskite-oxides, such as (La,Sr)CoO3 and (Ba,Sr)CoO3, have received much attention in recent years as cathode materials for intermediate temperature-solid oxide fuel cells (IT-SOFCs). In this study, we have investigated the structural, electrical, electrochemical, and redox properties of Sm0.5Sr0.5Co1-x
Nb
x
O3-

d
(SSCNbx) cathodes under conditions relevant to IT-SOFC operation. The SSCNbx (x = 0, 0.1) oxides show gradually decreasing electrical conductivity with increasing Nb doping at the same temperature. The maximum power density of SSCNbx (x =0.1) is lower than that of SSC; however, SSCNbx (x = 0.1) is more stable than SSC considering the thermodynamic behavior, as determined through redox isotherms. These results suggest that a Nb doped SSC perovskite is suitable, considering its high power density and reasonable redox stability, as an IT-SOFC cathodematerial.
Lanthanide Nickelates Ln2NiO4+
δ
(Ln = La, Pr or Nd): Promising Cathode Materials For Metal Supported Cells
Authors: Grenier Jean-Claude , Flura Aurélien , Dru Sophie , Nicollet C. , Vibhu Vaibhav , Fourcade Sébastien , Rougier Aline , Bassat Jean-Marc , Brevet Aude , Mougin Julie
Published: October 2013

The cell manufacturing of Metal Supported Cells (MSC) for IT-SOFC application (typically 600 °C) requires to operate under non oxidizing conditions at high temperature (typically > 950 °C). The most sensitive layer appears to be the cathode one, usually a mixed ionic and electronic oxide. The behavior (TGA, XRD analyses, TECs) of the lanthanide nickelates Ln2NiO4+δ (Ln = La, Pr or Nd) is reported when sintered at high temperature, under low pO2, down to 10-4 atm. Electrochemical Impedance Spectroscopy measurements on Ln2NiO4+δ//GDC//YSZ half cells sintered either in air or under argon at various temperatures show polarization resistance values that meet the target requirements (< 0.20 W.cm² at 600 °C), especially for La2NiO4+
δ and Pr2NiO4+
δ. These results are discussed in terms of structural and microstructural features.
Evaluation of the Cathode Performance and the Distribution of Deposited Cr Species in the LSCF6428 Cathode by Cr Poisoning
Authors: Cho Do-Hyung , Kishimoto Haruo , Yamaji Katsuhiko , Brito Manuel E. , Bagarinao Katherine Develos- , Nishi Mina , Shimonosono Taro , Wang Fangfang , Yokokawa Harumi , Horita Teruhisa
Published: October 2013

The Cr poisoning behavior of LSCF6428 cathode was investigated under Cr-containing vapor conditions at 1073 K using LSCF6428/GDC/Pt cells. When exposed to the Cr-containing vapor, the polarization resistance (low frequency contribution) evaluated from the fitting results of AC impedance measurements of the samples was significantly increased. The sample operated under polarization condition for a longer time (380 h) had higher Cr concentration and lower Sr concentration inside the LSCF cathode, but its resistance was lower compared to the sample operated for a shorter time (75 h) under OCV condition. Microstructural and compositional analysis of the samples operated under polarization condition revealed a significant change in microstructure related to Sr transport. The detailed concentration of Cr and Sr inside the porous LSCF cathode was quantitatively measured by secondary ion mass spectrometer (SIMS), from which the distributions of Cr and Sr inside the porous LSCF cathode after Cr poisoning were derived.
Electrochemical Performance and Reaction Mechanism of LaNi0.6Fe0.4O3-δ
– Ce0.9Gd0.1O1.95 Composite Electrode for Solid Oxide Fuel Cell
Authors: Budiman Riyan Achmad , Hashimoto Shin-ichi , Yashiro Keiji , Amezawa Koji , Kawada Tatsuya
Published: October 2013

Composite cathodes consisting of multiphase materials have been attracted attention for the application at the intermediate temperature range of SOFC. The strategy has been applied to combine the electronically conductive electrode with ionically conducting oxide resulting high electrochemical performance at intermediate temperature. This idea is also applied into LaNi0.6Fe0.4O3-δ
as alternative cathode SOFC which combined with Ce0.9Gd0.1O1.95 to improve the electrochemical performance. In this study, the appropriate volume ratio and sintering temperature of the composite are affecting the electrochemical performance will be shown, and the detailed electrochemical reaction mechanism also will be discussed as aid for the further research.
The Effects of Minor Components in LSCF Cathode on Oxygen Reduction Reaction
Authors: Oishi Junya , Otomo Junichiro , Oshima Yoshito , Koyama Michihisa
Published: October 2013

Minor components in a porous electrode of solid oxide fuel cells (SOFCs) can affect the electrode performance. In this study, we focus on minor components derived from raw materials and production processes. Standard polycrystalline dense cathode samples of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) were prepared using high purity raw materials by Pechini method. To evaluate the effects of the minor components on LSCF performance, minor components such as Ba, Ca, Al and Si were added to the LSCF samples. Chemical diffusion coefficient (D
chem) and surface exchange coefficient (k
tr) were obtained as cathode performance factors by the conductivity relaxation measurement. The results showed that Al and Si have mostly negative effects for oxygen reduction reaction on LSCF while Ba and Ca were inert or showed positive effects for the cathode performance. We also discussed the mechanism of positive effect of Ca (D
chem,STD ≤ D
chem,Ca and k
tr,STD ≤ k
tr,Ca ) using XPS measurement.
Direct Evaluation of Oxygen Chemical Potential Distribution in an SOFC Cathode by In Situ X-Ray Absorption Spectroscopy
Authors: Fujimaki Yoshinobu , Watanabe Hidetaka , Terada Yasuko , Nakamura Takashi , Yashiro Keiji , Hashimoto Shin-ichi , Kawada Tatsuya , Amezawa Koji
Published: October 2013

Oxygen chemical potential distribution in a porous La0.6Sr0.4CoO3-δ
(LSC64) electrode on a Ce0.9Gd0.1CoO1.95-

δ
(GDC) electrolyte under polarization was evaluated by using in situ X-ray absorption spectroscopy (XAS) at P(O2) = 10-2 bar and 873 K. The application of synchrotron X-ray focused into the submicrometer size enabled us to experimentally clarify the oxygen potential distribution in the vicinity of electrode/electrolyte interface with the position resolution of micrometer. Electrochemical impedance spectroscopy (EIS) measurements, followed by the analysis assuming the transmission line model (TLM) as an equivalent circuit, were performed with the same electrochemical cell for the XAS measurements. Based on the results by in-situ micro XAS and EIS measurements, the effective reaction area in the porous LSC64 electrode was discussed.
Optimization of Water-Based Cathode Inks for Solid Oxide Fuel Cells
Authors: Howe Katie Sarah , Song Zhi H. , Kueh Tze H. , Steinberger-Wilckens Robert , Dhir Aman
Published: October 2013

A new cathode ink for a solid oxide fuel cell has recently been developed (UK Patent Publication Number GB2490869). It was found to give a power density of 0.33 W/cm2 at 0.7 V at 750°C running on hydrogen. Further optimisation work has been undertaken, focusing on the dispersant: Poly(N-VinylPyrrolidone) - PVP. The effects of chain length and weight percentage of PVP have been investigated, and Poly (ethylene glycol) – PEG - was tested for comparison. PEG was found to give good performance at lower weight percentages, but had a negative impact on ink rheology at higher concentrations. Optimisation of the ink formulation increased the power at 0.7 V to 0.46 W/cm2 under identical test conditions.
Evaluation of Power Generation Performance, Durability, Adhesive Strength and Firing Temperature of SOFC Cells
Authors: Ogura Yusuke , Shimano Jun , Hisada Kohji
Published: October 2013

One of the reasons for the degradation of solid oxide fuel cells (SOFC) is the released adhesion between the cathode and the interlayer on the electrolyte. The adhesion strength and the power generation performance of cells are dependent on the firing temperature of the cathode in fabrication. In this study, in order to find the adequate firing temperature for the cathode, we fabricated cells by firing the cathode at several temperatures, and evaluated the power generation performance, the adhesive strength, and the durability performance. These examination results suggest that the cells fired at 1050°C and 1100°C are adequate for our cathode.
Improvement of Oxidation Resistance of Crofer 22APU With Modified Surface for Solid Oxide Fuel Cell Interconnects
Authors: Demeneva Nataliya , Bredikhin Sergey
Published: October 2013

One challenge for advancing solid oxide fuel cell (SOFC) technology is to develop interconnect materials with adequate conductivity and stability in oxidizing atmosphere for efficient long-term use. The objective of the present work is development of a two-step process which leads to the formation of internal barrier layer for Cr diffusion to the surface of current collector. ”Current collector with modified surface layer-LSM cathode” junctions were tested at 850ºC in air and current density 0,5A/cm2. Exposure time was up to 21000 hour. It was found that an irregularly shaped layer of thickness 2–5 mm was formed at a depth of 6–8 mm from the surface of current collector with modified near surface layer. Investigation of the composition showed that this irregularly shaped layer consists of a Cr2O3 phase and the thickness of such Cr2O3 islands increases as a function of operational time. The observed formation of such an internally oxidized Cr layer suppresses the formation of the insulating Cr2O3 phase on the current collector surface and improve electrical conductivity.
Electrodeposition Method for SOFC Interconnector Coating
Authors: Inoue Shuichi , Nonaka Hidemasa , Saito Tadashi , Yoda Masakazu , Takuwa Yuya
Published: October 2013

We developed the high durability coating for SOFC metal interconnectors. The method is anion type electrodeposition coating, and the material of coating is spinel type oxide. Generally, electrodeposition coating is used to form the resin based coating, but we successfully increase the amount of ceramics in the film and enable this method for coating of SOFC metal interconnectors. This coating method enables the uniform coating thickness regardless of the structure of metal interconnectors. We demonstrated the high durability data of interconnector tests in terms of the degradation rate of ASR and Cr poisoning. This coating method is available for any ceramics and quite economical.
Long Term Performance of Stacks with Chromium-Based Interconnects (CFY)
Authors: Brandner Marco , Bienert Christian , Megel Stefan , Kusnezoff Mihails , Trofimenko Nikolai , Sauchuk Viktar , Venskutonis Andreas , Kraussler Wolfgang , Michaelis Alexander , Sigl Lorenz S.
Published: October 2013

Chromium-based interconnects (CFY) in combination with electrolyte supported cells are perfectly matching the requirements of different SOFC applications. Furthermore, this type of stacks and the related manufacturing of cells and interconnects is already proven in very high volumes today. Plansee SE and Fraunhofer IKTS, together with partners in the SOFC20 project and lead customers, have developed the advanced MK351 stack-platform, which is now available for interested new customers. A suitable, well-adjusted combination of materials, especially regarding the cathode protection and contacting, has been developed. Sample test results have been verified in long term stack testing for more than 8,000 h. The stack has proven very low power degradation of less than 0.7 %/ 1,000 h.
Precoated AISI441 for SOFC Interconnectors Studied by TEM Methods
Authors: Lundberg Mats W , Karlsson Lisa S , Berger Robert , Folkeson Nicklas , Westlinder Jörgen , Holmberg Håkan
Published: October 2013

Precoated AISI441 (EN 1.4509) for SOFC interconnectors were investigated using energy-filtered transmission electron microscopy (EFTEM) and electron energy-loss spectroscopy (EELS) looking at the diffusion processes in the initial stage of the oxidation. The PVD coating contained Ce and Co/Mn-alloy in two layers with at total thickness of 800nm. The samples were exposed up to 168 hours at 800°C then characterized by TEM. In parallel cyclic oxidation and chromium volatilization studies have been performed. The studies have revealed that the Ce retard the outward migration of Cr though the scale and that the discrete Ce layer transforms to isolated nanoparticles during initial oxidation.
Development of Protective Coatings for SOFC Metallic Components
Authors: Kidner Neil J , Arkenberg Gene , Ibanez Sergio , Smith Kari , Akanda Sajedur R. , Seabaugh Matthew M. , Walter Mark E
Published: October 2013

The adoption of oxidation resistant, high-temperature alloys as alternatives to traditional ceramic interconnect materials for intermediate-temperature solid oxide fuel cells is critical to satisfy the aggressive cost targets necessary for their successful development. The effect of processing conditions on the microstructure and electrical performance of manganese cobaltite oxide coatings for the protection of ferritic stainless steel interconnects has been investigated. Using the standard aerosol spray deposition (ASD) based process which includes a reduction firing operation a highly dense MCO coating is formed that acts as an effective barrier to high temperature oxidation and chromium volatilization. Excellent long-term electrical and microstructural stability of the MCO coating has been demonstrated under application specific conditions. Omitting the reduction firing step is shown to significantly degrade the coating microstructure which is unable to densify sufficiently to form an effective protective oxide coating.
Effect of Ceramic Filler Particles on the Sealing Capability of a SrO-Based Glass Seal
Authors: Je Hae-June , Yoon Kyung Joong , Son Ji-Won , Lee Jong-Ho , Kim Byung-Kook , Lee Hae-Weon
Published: October 2013

The nano-sized YSZ and nano-sized Al2O3 powders were added to a SrO-Al2O3-B2O3-SiO2 glass system to control the effective viscosity and glass retention. Added filler particles evidently improved glass retention. YSZ/glass composites hardly devitrified after heat treating at 800 oC for 100 hours but Al2O3/glass composites easily devitrified. The devitrified phase, SrAl2Si2O8, decreased the CTE of Al2O3/glass composite to 5.6x10-6 /oC. Corrosion of Crofer22/APU was more severe due to contact with Al2O3/glass composite than with YSZ/glass composite. YSZ composite/glass showed the reliable sealing capability in long-term operation and repeated thermal cycles while the sealing of Al2O3/glass composite failed during thermal cycling. Such failure of Al2O3/glass composite was caused not only by the large thermal mismatch between Crofer22APU jig and sealing tape but also by intensifid corrosion of Crofer22APU.
Internal Multi-Physics Phenomena of SOFC with Direct Internal Reforming
Authors: Menon Vikram , Janardhanan Vinod M , Tischer Steffen , Deutschmann Olaf
Published: October 2013

This paper presents a detailed model to evaluate power density, species concentration, operating current/voltage, efficiency and temperature of a solid oxide fuel cell (SOFC) operating under direct internal reforming conditions. The computational framework, at the unit-cell level, encompasses a detailed 42-step reaction pathway for heterogeneous chemistry in the anode structure (Ni based catalysts), modified Butler-Volmer formalism to represent charge transfer chemistry, Dusty Gas Model for the porous media transport and a simple 1D solid-phase heat balance model. Simulations are performed for configurations ranging from simple 1D electrochemical cells to quasi-2D unit cells to complex 3D stacks, to elucidate the effectiveness of the tool for performance and design optimization.
Three-Dimensional Design Optimization of an Anode-Supported SOFC Using FEM
Authors: Andersson Martin , Yuan Jinliang , Sundén Bengt
Published: October 2013

Solid oxide fuel cells (SOFCs) are promising as energy producing devices, which at this stage of development will require extensive analysis and benefit from numerical modeling. A 3D model is developed based on the FEM for a single cell planar SOFC design optimization. Ion, electron, heat, gas-phase species and momentum transport equations are implemented and coupled to the kinetics of electrochemical reactions. High current density spots are identified, where the electron transport distance is short and the oxygen concentration is high. The relatively thin cathode results in a significant oxygen mole fraction gradient in the direction normal to the main flow direction. The electron transport especially within the cathode is found to be limiting for the electrochemical reactions at positions far from the channel walls (interconnect ribs). It is concluded that an increased pore size in the cathode support layer increases the current density more than an increased pore size in the anode support layer.
Three-Dimensional Performance Simulation of SOFC Anodes Using FIB-Tomography Reconstructions
Authors: Häffelin Andreas , Joos Jochen , Weber André , Ivers-Tiffée Ellen
Published: October 2013

In this contribution a three-dimensional (3D) finite element method (FEM) model that enables the performance simulation of solid oxide fuel cell (SOFC) Ni/YSZ cermet anodes is presented. The 3D FEM anode model enables the spatially resolved simulation of the electrochemical processes at the triple phase boundary (TPB) and the intrinsic coupling with the ionic, electronic and gaseous transport in the complex three-phase microstructure. Experimental data obtained from measurements with patterned model anodes are used for a detailed description of the electro-oxidation kinetics at the TPB. This numerical approach is combined with 3D reconstructions gained by focused ion beam (FIB) tomography used as the model geometry. Hence, all critical microstructure parameters are intrinsically considered in the 3D anode model. Simulations for a reconstructed anode functional layer were conducted for a temperature range between 450°C and 950°C. The simulated performance showed a good agreement with experimental data of technical Ni/YSZ cermet anodes.
Phosphine Induced Anode Performance Degradation in a Planer SOFC: A Numerical Study
Authors: Sezer Hayri , Pakalapati Suryanarayana Raju , Celik Ismail Bektas
Published: October 2013

A mathematical model which was validated using button cells is used to predict the phosphine induced performance degradation in relatively large planar cells operating on hydrogen fuel. The empirical model parameters are calibrated using button cell experiments as guide. These parameters are then used to perform simulations to predict fuel contaminant performance degradation of planar cells. The results from the three dimensional model show that the contaminant coverage of Nickel and fuel distribution inside the anode is highly non-uniform. These non-uniform distributions are caused by the geometrical alignment of gas channels and current collectors, as well as the variation of gas concentration along the flow direction. The non uniform deactivation of anode gave raise to altering of current distribution inside the planar cell such that the cell can still produce current even when some regions of the anode are partially inactive. This is in stark contrast with what is observed in button cells where all the distributions are essentially one-dimensional. It is thus observed that the life time for planar cells could be much longer than that for similar button cells.
Atomistic Investigation of the Second Phase Precipitation in (Sr,La)TiO3 Interconnect Material
Authors: Nakamura Kaoru , Mori Masashi , Ohnuma Toshiharu
Published: October 2013

We investigated the second phase precipitation in (Sr,La)TiO3 interconnect materials in SOFC by utilizing first-principles calculation. Our calculation showed that homologous phase La2Ti2O7 is more stable than monoclinic pyrochlore phase by 0.59 eV/f.u. From the consideration of the precipitation mechanism and phase stability, Ruddlesden-popper phase and homologous phase are thought to precipitate within perovskite lattice under SOFC operation. Calculated band gaps of Ruddlesden-popper phase, pyrochlore phase and homologous phase were larger than that of pristine SrTiO3. These intrinsic electronic state of precipitates should affect the electrical conductivity of (Sr,La)TiO3 ceramics. Defect formation energy showed that La element and cation vacancy tend to segregate at grain boundaries, and work as sources of the precipitation.
Enhancing SOFC-Stack Performance by Model-Based Adaptation of Cathode Gas Transport Conditions
Authors: Geisler Helge , Kornely Michael , Weber André , Ivers-Tiffée Ellen
Published: October 2013

High performance anode–supported cells (ASC), contacted in a planar stack by metallic interconnectors (MIC), undergo a significant power density reduction. Performance limiting factors originating from the MIC-design were identified by detailed experimental data analysis and via a straightforward FEM simulation. Conclusively, gas diffusion polarisation contributes close to the sum of all ohmic losses to the overall polarization, both controlling stack performance. Based on this knowledge, a multiphysic-FEM-model was developed, considering coupled ohmic, gas diffusion and nonlinear polarization losses in the electrodes and ohmic losses in the electrolyte. Consequential ASC-performance depends over a broad range of operating conditions on i) an optimal MIC-design and ii) a well-chosen cathode thickness increases the overall power output.
Operation of Metal-Supported SOFC with Charcoal Fuel
Authors: Tucker Michael C , Taylor Cindy , LaBarbera Mark , Jacobson Craig P
Published: October 2013

Point Source Power develops consumer products incorporating metal-supported SOFC technology licensed from Lawrence Berkeley National Laboratory. The first product is the VOTOTM, designed to operate in wood- or charcoal-burning cookstoves prevalent throughout the developing world. The VOTOTM is fueled by charcoal, and heated to 650-850°C operation temperature during cooking, producing a few watts of electricity. Particular challenges when using charcoal fuel include: thermochemistry in the anode chamber, identification of electrochemically-active species, mineral content of wood chars, and thermal activation of the desired reactions. Power density in excess of 100 mW/cm2 is achieved at 800°C. Performance below 700°C is severely limited.
Performance Improvement of Ni-YSZ-Based Solid Oxide Fuel Cell with the Anode Functional Layer Synthesized by Co-Precipitation Method
Authors: Lee Jin Goo , Park Myung-Geun , Ryu Kwang Hyun , Song Rak Hyun , Park Seok Joo , Min Sung Hwan , Hyun Sang-Hoon , Kim Chang Soo , Shin Dong Ryul , Shul Yong Gun
Published: October 2013

The nanopowder for the Ni-YSZ anode functional layer (AFL) was prepared by ammonium carbonate co-precipitation method. The electrolyte thickness of the Ni-YSZ-based cell with the anode functional layer was about 16 μm. The anode functional layer coated 2times by dip-coating method was 18 μm in thickness. Compared to the Ni-YSZ cell without AFL, the cell performance was greatly increased in the cell with AFL, showing above 0.6 Wcm-2 at 800 °C. This result exceeds 0.35 W cm-2 of the cell without AFL at the same temperature by approximately two times. Thus, the anode functional layer synthesized by co-precipitation method can be a promise for the performance improvement of YSZ-based solid oxide fuel cells in intermediate temperature range.
Study of Ceria-Nickel Composites for Anode Catalytic Layer for Direct Ethanol SOFC
Authors: Fonseca Fabio C. , Tabuti Francisco N. , Noronha Fabio B. , Augusto Bruno L. , Matos Lisiane V.
Published: October 2013

A hydrothermal route was used to synthesize gadolinia-doped ceria with highly dispersed Ni particles. The microstructural and electrical properties of the cermet revealed that Ni attained percolation at relatively low volume fraction. The cermet was used as a catalytic layer deposited onto the standard Ni-based anode and allowed for the stable operation under ethanol. No evidence of carbon deposits was identified after 50 hours of continuous operation under dry ethanol. Such a result was attributed to both the catalytic properties of the ceria layer and the operation mechanism of gradual internal reforming.
Biogas Upgrading: By Steam Electrolysis or Co-Electrolysis of Biogas and Steam
Authors: Hansen John Bøgild , Fock Felicia , Lindboe Hans Henrik
Published: October 2013

Biogas can be upgraded by means of SOEC technology. Steam added to biogas and the CO2 content can be co-electrolyzed generating a CO rich synthesis gas. Alternatively hydrogen from steam electrolysis can be added to the biogas. In both cases thesynthesis gas is methanated. Waste heat from the methanator is used as feed for the SOEC. The paper will compare the energy and exergy efficiency as well as the economics of the two routes in future energy scenarios with a large power fraction from wind.