bluuebunny/crossref_metadata_2025 huggingface dataset:
The Status of Metal-Supported SOFC Development and Industrialization at Plansee
Authors: Franco Thomas , Haydn Markus , Weber André , Schafbauer Wolfgang , Blum Ludger , Packbier Ute , Roehrens Daniel , Menzler Norbert H. , Rechberger Juergen , Venskutonis Andreas , Sigl Lorenz S. , Buchkremer Hans Peter
Published: October 2013

Benefiting from a strong cooperation with Forschungszentrum Jülich, Karlsruhe Institute of Technology (KIT), and AVL List GmbH respectively, Plansee has been focusing on the development and industrialization of metal-supported SOFC and components for mobile applications. In the scope of some challenging development projects a novel MSC configuration and a first pilot fabrication route could be demonstrated successfully. Currently, the work is ongoing towards a continuous and reliable manufacturing of standard cells as well as the demonstration of system-relevant stack tests. This paper gives an overview about the latest results in cell and stack development as well as about the manufacturing route for cost-effective metal-supported cells.
R&D and Commercialization of Metal-Supported SOFC Personal Power Products at Point Source Power
Authors: Tucker Michael C , Carreon Bernard , Charyasatit Jeffrey , Langston Kenny , Taylor Cindy , Manjarrez Jose , Burton Nicholas , 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 biomass, and heated to 650-850°C operation temperature during cooking, producing a few watts of electricity. Metal-supported cell and stack technology are developed that enable operation in the uncontrolled cookstove environment. Particular challenges overcome include: rapid thermal cycling during cooking-fire light-off; maintaining optimum operating temperature; and, degradation of the cell by contaminants in the cookstove.
Microstructural Change of Ni–YSZ Anode under Thermal Cycles with Redox Treatments
Authors: Kubota Masaru , Muroyama Hiroki , Matsui Toshiaki , Eguchi Koichi
Published: October 2013

Nickel–yttria-stabilized zirconia (Ni–YSZ) is widely used as an anode material for solid oxide fuel cells (SOFCs). However, it is concerned that the performance of Ni–YSZ anode is deteriorated by redox treatments accompanied with the microstructural change. In this study, we investigated the correlation between the performance deterioration and the microstructural change of Ni–YSZ anode subjected to thermal cycles with redox treatments (thermal–redox cycles: repetition of oxidation in cooling and reduction in heating processes). The microstructural change of anode was quantified by focused ion beam–scanning electron microscopy (FIB–SEM). The decrease in the active triple phase boundary (TPB) length caused by sintering of Ni particles was correlated with the performance deterioration. We also found that the reduction onset temperature at 500 ºC in the heat-up process promoted the agglomeration of Ni particles as compared with that at 900 ºC.
Performance Evaluation Technology for Long Term Durability and Reliability of SOFCs
Authors: Mugikura Yoshihiro , Yasumoto Kenji , Morita Hiroshi , Yoshikawa Masahiro , Yamamoto Tohru
Published: October 2013

Long term durability and reliability tests of four different types of SOFCs, which have been developed by MHI, TOTO, Kyocera, and Tokyo Gas Co., Ltd. were carried out under the NEDO project. In this study, we report a dominant performance factor for four different types of SOFCs. The performance factors such as internal resistance and polarizations of anode and cathode were determined by the electrode performance model. Using the improved Segment-in-series type stack, long-term durability test for 15,000 hours with chromium vapor containing in air was carried out. By having applied the ceria based middle layer between the cathode and the electrolyte, it was shown clearly that the degradation rate was very small and was below 0.25%/1,000hr which is the target of degradation rate. Long-term durability test by 20,000 hours was carried out for 2008 model of Flattened tubular type stack. The degradation rate of this stack was 0.29%/1,000hr which is almost cleared the target of degradation rate.
Durability of SOFC Against Thermal and Redox Cycling
Authors: Hanasaki Masahiro , Uryu Chie , Taniguchi Shunsuke , Shiratori Yusuke , Sasaki Kazunari
Published: October 2013

Durability of cells and stacks against thermal cycling and redox cycling is essential for practical SOFCs, in which the system experiences various kinds of cycling conditions, including the shutoff of fuel supply. In this study, we have investigated the influence of thermal cycling conditions, such as hot-standby, cold-standby, and shut-down, on the cell performance degradation.
Experimental Investigation of the Effect of Operating Pressure on the Performance of SOFC and SOEC
Authors: Momma Akihiko , Takano Kiyonami , Tanaka Yohei , Kato Tohru , Yamamoto Atsushi
Published: October 2013

The effect of operating pressure on the performance of SOFC and SOEC was investigated electrochemically under pressurized and depressurized conditions (0.01-1.0 MPa) using practical size single cells. It was found that the diameter of low frequency semi-circle appears in impedance spectra was not so much affected by operating pressure with electrolyte supported cell as was expected theoretically for gas conversion impedance. On the other hand, the diameter significantly depends on the operating pressure with anode supported cell especially when the operating pressure becomes low, indicating the contribution of diffusion to the semi-circle. Numerical simulation in which diffusion processes in electrodes were considered was proposed to explain the observed behavior.
Performance of Electrolyte Supported Solid Oxide Fuel Cells with STN Anodes
Authors: Veltzé Sune , Sudireddy Bhaskar Reddy , Jørgensen Peter Stanley , Zhang Wei , Kuhn Luise Theil , Holtappels Peter , Ramos Tânia
Published: October 2013

In order to replace the state of the art Ni-cermet as SOFC anode, electrolyte supported cells comprising CGO/Ni infiltrated Nb-doped SrTiO3 anodes, and LSM/YSZ cathodes have been developed and tested as single 5 x 5 cm2 cells. The initial performance reached 0.4 W/cm2 at 850 °C. Further tests under high fuel utilization and redox cycling have been performed to identify the performance limiting parameters in this new type of full ceramic SOFCs. Measured performances and stability have been further tentatively linked to modifications of the nano-sized infiltrates within the anode.
Fabrication and Characterization of Intermediate Temperature Solid Oxide Fuel Cells by Pulsed Laser Deposition
Authors: Zhao Liang , Sasaki Kazunari , Bishop Sean R.
Published: October 2013

Decreasing the operating temperature in solid oxide fuel cells (SOFCs) will aid in increasing their portability and durability. However, the electrolyte and electrode resistances increase significantly at lower temperatures. Pulsed Laser deposition (PLD) is a promising method to prepare thin films, thus reducing the ohmic resistance of the electrolyte and electrode, with microstructural and morphological control depending on deposition conditions, keys to maximizing electrode electrochemical performance. In this research, SOFC cells consisting of anode/electrolyte/cathode thin film layers grown by PLD on electrically conductive porous supports were fabricated. The microstructure control of cathode and anode functional layers in different deposition conditions are discussed.
Enhancing the Protonic Conductivity of Tin Pyrophosphates by Increasing Phosphate Content
Authors: Kreller Cortney R. , Wilson Mahlon S. , Mukundan Rangachary , Brosha Eric L. , Garzon Fernando H
Published: October 2013

Indium-doped tin pyrophosphate materials were synthesized with varying metal to phosphate ratios to assess the influence of the excess amorphous polyphosphate phase on conductivity. Total conductivity at 250¢ªC was found to increase with increasing P:M ratio, with a maximum conductivity of 10-1.8 Scm-1 in dry N2 and 10-0.8 Scm-1 in humidified N2. These results combined with supporting spectroscopy, suggest that a grain-boundary polyphosphate phase is required to achieve high conductivity at low-intermediate temperatures. The conductivity of the excess phosphorous content materials was stable in both dry and humidified environments at 250¢ªC. The use of this material as a promising fuel cell electrolyte was demonstrated with a maximum power density of 11 mWcm-2 obtained for the highest P:M ratio material at 300¢ªC without humidification. This value is an order of magnitude lower than what has been reported previously in the literature. However the conductivity of the electrolyte in the operating fuel cell was 0.075 Scm-1 and the poor performance is attributable to cathodic overpotentials.
Stress Conditions Transition by Thermal Annealing in Barium Zirconate Based Proton Conducting Thin Films Fabricated Using PLD Method
Authors: Fukushige T. , Iguchi Fumitada , Shimizu Makoto , Yugami Hiroo
Published: October 2013

Barium zirconate based proton conducting thin films were fabricated using PLD method with ArF Excimer laser under high and low oxygen partial pressures on silicon wafers, and stress conditions and its transition by thermal annealing were measured by XRD side inclination method. Stress conditions were changed by thermal annealing, and two stress transition modes were observed. Stress condition in the films deposited at high oxygen partial pressure was compressive and the value was changed to tensile by thermal annealing. Considering the difference of thermal expansion coefficient, stress condition due to thermal stress was tensile. Therefore, this transition was defined as stress relaxation. By contrast, the films deposited at low oxygen partial pressure showed tensile stress condition, and transited to compressive stress condition, i.e. stress increment. These two modes were probably due to the transition of intrinsic stress caused by surface energy, which was sensitive to the deposition atmospheres.
Yttrium Doped Barium Cerate and Zirconate Heterostructures: Deposition and Electrochemical Characterization
Authors: Di Bartolomeo Elisabetta , D'Epifanio Alessandra , Yang Nan , Tebano Antonello , Balestrino Giuseppe , Licoccia Silvia
Published: October 2013

Epitaxial heterostructures consisting of an yttrium doped barium cerate (BCY) layer sandwiched between two yttrium doped barium zirconate (BZY) thin layers have been deposited on insulating (001) MgO substrates by pulsed laser deposition. The first BZY layer was aimed at improving the lattice match with the MgO substrate, the second at protecting the BCY layer. Ionic conductivity has been studied in the 300 – 600 °C temperature range as a function of the BCY thickness. Due to the absence of blocking grain boundaries, heterostructures showed a conductivity larger than that of BCY pellets sintered under optimized conditions.
Alkaline-Earth Doped Effect on Oxygen Vacancy Migration in Monoclinic Lanthanum Germanate: First-Principles Calculation
Authors: Linh Tran Phan Thuy , Sakaue Mamoru , Alaydrus Musa , Wungu Triati Dewi Kencana , Aspera Susan Meñez , Kasai Hideaki , Ishihara Tatsumi
Published: October 2013

First-principles calculations were performed to evaluate the effects of alkaline-earth (M = Ba, Sr, Ca) doped monoclinic La2GeO5 on oxygen ion conduction. Electronic densities of states of the doped systems La1.75M0.25GeO4.75 showed insulating majority and semiconducting minority spin states while both the perfect La2GeO5 and oxygen-deficient La2GeO4.75 systems are electronically insulating. Oxygen vacancy formation energies decreased significantly in doped systems. We determined the activation barrier by performing climbing image nudged elastic band calculations. The similarity in ionic radii causes the lowest activation barrier in Ca-doped case, which is in agreement with an experiment. Consequently, Ca is the most favorable dopant to La site in La2GeO5.
Effect of Bi3+ Doping on the Property and Performance of the (La0.9Sr0.1)0.98Ga0.8Mg0.2O3-δ Electrolyte
Authors: Zhou Qiang , Meng Xie , Zhan Zhongliang
Published: October 2013

Co-doped samples of (La0.9Sr0.1-xBix)0.98Ga0.8Mg0.2O3
-
δ(LSBGM, x=0.00, 0.02, 0.05, 0.08 and 0.1) were synthesized using glycine-nitrate process (GNP) and properties were characterized to explore their use as a solid electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). The effects of Bi3+ doping on phase formation, sinterability and electrical conductivity were investigated and showed that doping Bi3+ to LSGM can significantly reduce the LaGaO3 phase formation and sintering temperature meanwhile remain relatively high ionic conductivity, indicating that Bi3+-doped LSGM is a potential candidate as a solid electrolyte for IT-SOFCs.
Zirconia Ceramics Effect of Fe2O3 Addition on Conductivity of YSZ Ceramics
Authors: Barbashov Vladimir , Belousov Nikolay , Nesova Elizaveta , Jebel Anton
Published: October 2013

Effect of 2 mol. % Fe2O3 addition on conductivity of yttria stabilized zirconia ceramics (YSZ, 6-12 mol.% Y2O3) was established. For Fe doped material, it was shown that conductivity demonstrates maximum at 10 mol. % Y2O3, and its value increases by 1.4 times. It was shown using X-ray phase analysis that the material was predominantly in the cubic phase within the concentration range. Discussion of results was performed in terms of the model that assumes the control effect of hydrostatic pressure on oxygen ions diffusion.
Performance of LST-GDC Composite Anodes for Solid Oxide Fuel Cells
Authors: Fan Liquan , Wang Yuwei , Huo Hua , Xiong Yueping
Published: October 2013

La0.2Sr0.8TiO3 (LST) nanoparticles were fabricated by electrospinning. This material can be used as an alternative to the conventional nickel cermet anodes to solve the carbon deposition problem encountered in hydrocarbon fed solid oxide fuel cells (SOFCs). The phase pure LST material with perovskite structure has been obtained when the calcination temperature exceeds 800°C. The as-made LST nanoparticles were then sintered on ScSZ electrolyte at 1000°C to form nanoparticle-based LST anodes. In order to improve the electrochemical performance of the LST anode, Gd0.2Ce0.8O1.9 (GDC) precursor solution was infiltrated into the scaffolds formed by LST nanoparticles with different LST : GDC mass ratios. An optimal polarization resistance of 1.03 Ω cm2 has been achieved with the LST : GDC mass ratio of 1:0.50 when tested at 800 °C in 97% H2+3% H2O atmosphere. The result demonstrates the promising application of LST-GDC as SOFC anode material.
SOFC Anode Fabricated by Magnetically Aligning of Ni Particles
Authors: Nagato Keisuke , Shikazono Naoki , Weber André , Klotz Dino , Nakao Masayuki , Ivers-Tiffée Ellen
Published: October 2013

Ni particles are aligned by magnetic field during the drying process after screen-printing Ni/8YSZ (yttria-stabilized zirconia) paste. By applying a magnetic field, Ni particles are magnetically polarized, attracted to each other, and align along the magnetic field. It is proposed, that not only tortuosity of Ni but also that of YSZ and of pores is decreased. Symmetrical half cells are fabricated with 15-μm-thick anodes and 200-μm-thick YSZ electrolytes. A current collector made of porous Ni with a thickness of approximately 5 μm was printed on top of each anode. The microstructural changes in the anodes are analyzed by scanning electron microscopy. Impedance measurements are performed at 700°C in H2/H2O atmospheres containing 10% and 60% H2O. The initial polarization resistance was decreased after applying a magnetic field of 100 mT by up to 25%. However, with higher magnetic field, the polarization resistance increases, which might be explained by a pronounced increase of the surface roughness with 30 μm peak-to-valley, causing current constriction.
Understanding the Relationship between Ink Rheology and Film Properties for Screen-Printed Nickel/Scandia-Stabilized-Zirconia Anodes
Authors: Somalu Mahendra Rao , Muchtar Andanastuti , Baboli Mostafa Ghasemi , Yufit Vladimir , Shapiro Ian P. , Xiao Ping , Brandon Nigel P.
Published: October 2013

Optimization of SOFC electrode or electrolyte screen-printing ink processing conditions is critical to the reliable manufacture of high quality films with optimum properties. Hence, in this study, the relationship between the ink rheology and the screen-printed film properties were investigated using nickel/scandia-stabilized-zirconia (NiO/ScSZ) anode inks having various binder (0-5 wt%) and solid contents (20-35 vol%). Ink rheological tests showed increased particle network strength in the inks with increasing binder and solids content. The electronic conductivity and electrochemical performance of anode films also increased as a function of binder and solids content. These can be related to increased particle network strength within the inks, as confirmed from the rheological studies. In conclusion, from the perspective of ink rheology, screen-printability and performance, inks having 26 vol% solid with 3 wt% binder or 28-30 vol% solid with 2 wt% binder were determined as the most suitable for the manufacturing of high quality SOFC anode films with a thickness of around 10 μm.
Spin-Coated La0.8Sr0.2Ga0.8Mg0.2O3-δ Electrolyte on Infiltrated Anodes for Direct Methane Fuel Cells
Authors: Salehi Zahra , Luisetto Igor , Basoli Francesco , D'Epifanio Alessandra , Licoccia Silvia , Tuti Simonetta , Di Bartolomeo Elisabetta
Published: October 2013

Dense micrometric La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) films were deposited by spin-coating on porous LSGM scaffolds characterized by homogeneous pore structure. Porous anodes were infiltrated with aqueous nickel and nickel/copper nitrate solutions, dried and fired at 700 °C. Homogeneous metal coating with proper interconnection was observed by SEM, chemical stability confirmed by XRD, and electrical characterization of anodic substrates was performed. Catalytic activity of different anodes was evaluated ex-situ in a quartz micro-reactor fed with CH4:CO2 mixture at range 650 and 700 °C. To investigate the redox properties of the metallic phases, the anodic substrates were subjected to redox ageing cycles and characterized by H2-TPR.
A Solid Oxide Fuel Cell with Lanthanum and Calcium Co-Doped Strontium Titanate as Support
Authors: Lu Lanying , Verbraeken Maarten , Cassidy Mark , Irvine John T. S.
Published: October 2013

Alternative anodes are of great interest for robust solid oxide fuel cells (SOFCs). A-site deficient strontium titanate co-doped with lanthanum and calcium, La0.2Sr0.25Ca0.45TiO3 (LSCTA-), has been investigated as a potential anode for SOFCs. Flat multilayer ceramics have been produced by controlling the sintering behavior of LSCTA-, resulting in a 450 µm thick porous LSCTA- scaffold with a well adhered 40 µm dense YSZ electrolyte. Impregnation of CeO2 and Ni has resulted in power densities of 0.96 Wcm-2 at 800 oC, higher than 0.125 Wcm-2 without impregnation and 0.38 Wcm-2 for Ni alone, demonstrating encouraging performance. Work continues to improve understanding of catalyst-scaffold interactions and scaling up the concept.
Synthesis and Properties of Perovskite Anode for SOFC Applications
Authors: Fung Kuan-Zong , Tsai Shu-Yi , Liu Chi-Yang
Published: October 2013

The degradation of Ni anode due to the carbon deposition has been observed when the hydrocarbon fuels are used. The perovskite anodes, on the other hand, are chemically and electrochemically stable under SOFC operating conditions. They exhibit increased resistance to carbon deposition compared to Ni anode. Furthermore, they appeared to be active towards the preferential oxidation of H2S. However, undoped perovskites such as titanates and vanadates do not show good enough structural and/or electrical properties. In this study, various amount of Sr substitution is used to enhance the structural and electrical properties of LaVO3 perovskite based on the defect chemistry consideration.
Comparison of Performance of Ni-CeO2-YSZ and Ni-Nb2O5-YSZ Anodes for Solid Oxide Fuel Cell
Authors: Tiwari Pankaj Kr , Basu Suddhasatwa
Published: October 2013

In the present work NiO-CeO2-YSZ (30:10:60) and NiO-Nb2O5-YSZ (30:10:60) anodes materials prepared by solid state route have been investigated to check the degradation of Ni anode due to coarsening by introducing CeO2 and Nb2O5. Ni-CeO2-YSZ and Ni-Nb2O5-YSZ anodes materials were prepared by solid state reaction route and painted on the one side of dense die pressed YSZ pellet sintered at1450ºC. The other side of pellet was coated with LSM-YSZ cathode sintered at 1250ºC. The as prepared button cells with Ni-CeO2-YSZ and Ni-Nb2O5-YSZ anodes showed peak power density 96 mW/cm2 and 127 mW/cm2 respectively in H2 at 800 ºC. Physical characterizations e.g., SEM, XRD, EDX and TEM of above mentioned anode materials were carried out to evaluate the performance of anode materials.
Material Selection Impact on Cell Performances
Authors: Pétigny Nathalie , Pétigny Sylvain , Josseaux Frédéric , Pattarkine Gaurav , Narendar Y.
Published: October 2013

Performances of solid oxide fuel cell is described and established in the literature as a function of the cell design and microstructural properties along with material composition. However, industrial platform to produce the different powders leads to different characteristics of these powders which can lead to difference in performances. Saint-Gobain is fabricating powders for SOFC application controlling accurately their chemistry. Different level of purity and dopant can thus be provided to reach the optimal composition for customers. A systematic study with different ionic conductors (YSZ) was carried out using Forschung Zentrum Julich cell design licensed by Saint-Gobain in 2006. YSZ powders developed by electrofusion have been successfully qualified in short term performances both in bulk anode and anode functional layer showing performances and strength similar to reference with a current density at 1.3A/cm2 at 800°C at 0.7V and bulk anode strength 85+/-5MPa.
Pattern Electrodes for Studying SOFC Electrochemistry
Authors: Patel Hrishikesh , Biradar Nitin , Venkataraman Vikrant , Aravind P
Published: October 2013

Pattern anodes can be used to localize reactions and study individual processes like charge transfer, adsorption, diffusion etc. Ceria and Nickel (Ni) pattern anodes were fabricated with the same dimensions with Triple phase boundary (TPB) lengths of 0.2707 m/cm2. Electrochemical Impedance Spectroscopy (EIS) of Ni anodes yielded results comparable with the results in literature (0.0001 Scm-2 at p
H2O = 2.4 kPa and 700oC). Ceria shows a different value for conductivity compared to the nickel, possibly because of the mixed electronic ionic conductivity of ceria and the spreading of the TPB over the surface of ceria. Identifying rate limiting mechanisms on ceria pattern anodes and comparing them with those of nickel gives a more complete picture about elementary processes at the cermet anode.
In-Operando Raman Characterization of Carbon Deposition on SOFC Anodes
Authors: Maher Robert C. , Duboviks Vladislav , Offer G. , Cohen Lesley F. , Brandon Nigel P.
Published: October 2013

Carbon formation within nickel-based solid oxide fuel cell (SOFC) anodes exposed to carbonaceous fuels typically leads to reduced operational lifetimes and performance, and can eventually lead to catastrophic failure through cracking and delamination. In-situ Raman spectroscopy has been shown to be a powerful characterization tool for the investigation of the dynamics of physical processes occurring within operational SOFCs in real time. Here we investigate the dynamics of carbon formation on a variety of nickel-based SOFC anodes as a function of temperature, fuel and electrical loading using Raman spectroscopy. We show that the rate of carbon formation throughout the SOFC anode can be significantly reduced through a careful consideration of the SOFC anode material, design and operational conditions.
Compatibility of Praseodymium Nickelates with Various Cathode Current Collectors and Electrolytes
Authors: Dogdibegovic E. , Templeton J. , Yan J. , Stevenson J. W. , Zhou Xiao-Dong
Published: October 2013

Nickelates, e.g. La2NiO4 and Pr2NiO4, have been of particular interest in the development of new generation oxygen electrodes for solid oxide fuel cells. The primary motivation for the utilization of nickelates is largely due to their resident oxygen interstitials, which are very mobile defects and thus capable of exchanging with ambient air at a substantially high rate. Indeed, nickelates exhibit superior electrochemical properties for oxygen reduction. Equally, if not more important research, is to investigate the stability of these electrodes with respect to time, temperature and compatibility with other constituents in a cell. In this paper, the high performance Pr2NiO4 cathode is reported together with its compatibility with various cathode current collectors and electrolytes. It was observed that at 750oC Pr2NiO4 is compatible with LSC or LSM current collectors up to 500 hours, but there exists an interdiffusion between Pr2NiO4 and ceria layer. Even with the presence of interdiffusion, the degradation rate at 0.8 V over 1000 hours was marginal, ~ 3% per 1000 hours.
Controllable Impregnation Via Inkjet Printing for the Fabrication of Solid Oxide Cell Air Electrodes
Authors: Da'as Eman Husni , Irvine John T. S. , Traversa Enrico , Boulfrad Samir
Published: October 2013

The impregnation method has been considered as one of the most successful techniques for the fabrication of highly efficient electrodes for solid oxide fuel and electrolysis cells (SOCs) at the lab scale. However, because the impregnation is usually performed manually, its irreproducibility remains a major problem that can be solved by using controllable techniques, such as inkjet printing. In this paper, lanthanum strontium manganite (LSM)/yttria stabilized zirconia (YSZ) air electrodes were prepared by infiltrating YSZ porous bodies with LSM precursor solution using inkjet printing, followed by annealing at 800°C for 2 hours. XRD analysis confirmed the formation of the LSM phase, which was in the form of nanoparticles with size in the 50-70 nm range on the YSZ walls, as revealed by FEG-SEM observations. The effect of printing parameters on the distribution of the impregnated phase was investigated and discussed.
Isolating the Role of Charge Localization in Chemical Expansion: (La,Sr)(Ga,Ni)O3-X Case Study
Authors: Perry Nicola H. , Thomas Jonathan E. , Marrocchelli Dario , Bishop Sean R. , Tuller Harry L.
Published: October 2013

The influence of electron localization on the chemical expansion coefficient was examined experimentally, using a model electrode material, (La,Sr)(Ga,Ni)O3-δ. Varying the Ni content yielded differing degrees of electron localization with resultant chemical expansion coefficients evaluated by dilatometry and thermogravimetric analysis in N2/O2 mixtures at 800 °C. In agreement with prior computational predictions, a decrease in chemical expansion coefficient was observed with electron delocalization.
Oxygen Nonstoichiometry and Electrochemical Properties in a Thin Film of Nickel　Substituted Lanthanum Cobaltite for SOFCs
Authors: Uzumaki Yuya , Hashimoto Shin-ichi , Nakamura Takashi , Yashiro Keiji , Amezawa Koji , Kawada Tatsuya
Published: October 2013

Oxygen nonstoichiometry of LaNi0.6Co0.4O3-δ
(LNC64) was measured by thermogravimetry, and electrochemical properties of thin film electrode were evaluated by ac impedance measurement around OCV and applied dc biases. At 873 and 973 K, δ in LaNi0.6Co0.4O3-δ
was below 0.003 in all measured p(O2) range while δ increased to 0.011 at p(O2) = 10-4 bar at 1073K. From the comparison between chemical capacitance which was estimated from the oxygen nonstoichiometry and evaluated from ac impedance measurement, it was suggested that the rate-determining step was surface reaction or bulk diffusion. The area specific interfacial conductivity σ
E for LNC64 film electrode was c.a.5.6 Scm-2 at 1073 K in air. Since the σ
E tendency in LNC64 film electrode well accorded with the oxygen nonstoichiometry and the capacitance for electrode reaction, it is suggested that ionic conduction was enhanced at 1073 K.
Spray Pyrolysis Assisted Synthesis of Doped Barium Ferrite and Lanthanum Barium Ferrite-Based SOFC Cathodes with Tailored Particulate Size and Morphology
Authors: Mukhopadhyay Jayanta , Basu Rajendra Nath
Published: October 2013

Doped barium ferrite [Ba1-xSrxCo1-yFeyO3-δ
(BSCF) 0 < x ≤ 0.5, y = 0.2 and 0.8] and lanthanum barium ferrite [Ba1-x-mLaxSrmCo1-yFeyO3-δ
(LBSCF); (x + m) = 0.75, m = 0.5, y = 0.2 and 0.8] based SOFC cathode with tailored particulate size and morphology are synthesized by spray pyrolysis. Near-net to spherical shape nano to micro particulates (100 nm - 5 µm) with in-built meso and micro porosity are prepared either by direct pyrolysis or by in-situ growth of nanoparticulates inside the reactor through homomolecular nucleation. Symmetric cells with optimized cathode particulate size, morphology and electrical conductivity reduce interfacial polarizations down to 0.048 Ω.cm2 and 0.014 Ω.cm2 at 700oC and consequently enhance the current densities to 1.8 Acm-2 and 2.2 Acm-2 (0.7 V, 700oC) with hydrogen and air for BSCF and LBSCF respectively. Microstructures of such cathodes are correlated with augmented cell performances for short and long term operation.
Development of Novel LSM/GDC Composite Cathode Material for Cathode-Supported Direct Carbon Fuel Cells
Authors: Ahmed Bilal , Lee Seung-Bok , Song Rak-Hyun , Lee Jong-Won , Lim Tak-Hyoung , Park Seok-Joo
Published: October 2013

A novel composite cathode material for cathode-supported direct carbon fuel cells (DCFCs) was developed and characterized in terms of phase stability, sintering behavior, electrical conductivity, mechanical strengths and microstructures. It was found that the newly developed LSM/GDC composite provides sufficient level of mechanical strength, electrical conductivity and porosity after sintering at 1300 °C and does not form any undesirable secondary insulating phases. The sintering behavior study showed that GDC inhibits sintering of LSM and thermal expansion coefficient (TEC) is compatible with other cell components. The preliminary results showed that LSM/GDC composite is suitable for cathode support applications.
Electrical Conductivity and Defect Structure of LaNi1-X
Fe
x
O3-δ
Authors: Niwa Eiki , Uematsu Chie , Mizusaki Junichiro , Hashimoto Takuya
Published: October 2013

The effect of cation composition in LaNi1-x
Fe
x
O3-δ
on oxygen nonstoichiometry has been investigated with iodometric titration. For LaNi0.6Fe0.4O3-δ
, temperature and oxygen partial pressure dependence of oxygen nonstoichiometry has been determined by equilibrium thermogravimetry. The P(O2) and temperature dependence of the electrical conductivity of LaNi0.6Fe0.4O3-δ
has also been measured. It has been clarified that δ generates with Ni substitution and maximum δ was observed for LaNi0.6Fe0.4O3-δ
. Temperature and P(O2) dependence of oxygen nonstoichiometry and electrical conductivity is small for LaNi0.6Fe0.4O3-δ
, probably because variation of average valence of B-site ion by temperature and P(O2) is small since charge compensation between Ni and Fe is easy to occur. The easy occurrence of the charge compensation corresponds to hopping conduction with small, temperature and P(O2) independent activation energy. By combination of oxygen nonstoichiometry and electrical conductivity, it has been clarified that LaNi0.6Fe0.4O3-δ
is p-type conductor with mobility of 0.257 cm2V-1s-1, which is independent on temperature and P(O2). Hole concentration at temperatures between 300 °C and 800 °C under -4 ≤ log{P(O2)/bar}≤0 is 3~4 x1021 cm-3.
Enhanced Chromium Tolerance of Gd0.1Ce0.9O1.95 Impregnated La0.6Sr0.4Co0.2Fe0.8O3-δ
Electrode of Solid Oxide Fuel Cells
Authors: Zhao L. , Amarasinghe S. , Jiang San Ping
Published: October 2013

The electrochemical activities and chromium tolerances are studied on pure La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Gd0.1Ce0.9O1.95 (GDC) impregnated LSCF (GDC-LSCF) electrodes of solid oxide fuel cells. Using electrochemical impedance spectroscopy (EIS) technology, a significant reduction in the electrode polarization resistance (RE) for O2 reduction particularly at low temperatures is obtained after GDC impregnated. Form the analysis results of EIS, the low frequency resistances are markedly reduced due to a positive effect of GDC coating on oxygen dissociative adsorption process. Most importantly, the overpotential (η) of GDC-LSCF electrode at 800 °C for 40 h in the presence of Fe-Cr metallic interconnect presents more stable than that of pure LSCF electrode, implying an enhanced Cr tolerance after GDC introduced. Moreover, SEM-EDS results indicate that Cr deposition is selective and occurs preferentially on LSCF surface rather than GDC, suggesting that GDC impregnation is a promising technique for the development of Cr-tolerance electrode in SOFCs.
Nano Coated Interconnects for SOFC (NaCoSOFC)
Authors: Froitzheim Jan , Magraso Anna , Holt Tobias , Lundberg Mats W , Windisch Hannes Falk , Berger Robert , Sachitanand Rakshith Nugehalli , Westlinder Jörgen , Svensson Jan-Erik , Haugsrud Reidar
Published: October 2013

The NaCoSOFC project is focused on the development of nano coatings for SOFC interconnects. The project is sponsored by the Nordic Top Level Research Initiative and has four project partners: Sandvik Materials Technology which is producing coated interconnects, Chalmers University of Technology and the University of Oslo that characterize samples with respect to e.g. corrosion, Cr evaporation and ASR as well as Topsoe Fuel Cell that is testing the developed interconnects in its stacks. The developed coatings are based on a combination of Co with RE elements and exhibit high corrosion resistance, 10 fold decrease in Cr evaporation and ASR values that are approximately 50% of the uncoated material.
Progress in SOFC Metallic Interconnect Coating
Authors: Du Xiaojia , Han Minfang , Sun Zaihong
Published: October 2013

Thin film coating is an effective way to enhance the anti-oxidation property of SOFC metallic interconnect at high temperatures and suppress chromia evaporation from stainless steel which easily causes cathode poisoning at cathode-electrolyte interface. The coating materials are mostly metal oxides and coating technologies are chosen to achieve dense films at low temperatures. In this paper, the SOFC interconnect coating materials and coating technologies developed in recent years are summarized, the effects of such coatings on SOFC stack performance are analyzed, and further development of SOFC interconnect coating is discussed.
Development of a Porous Metal Substrate for Metal Supported SOFCs Using a Fe-Cr-Al Stainless Steel
Authors: Pham Hung-Cuong , Park Eun-Joo , Taniguchi Shunsuke , Sasaki Kazunari
Published: October 2013

Metal supported cells with porous metallic substrates made of stainless steels are expected to drastically improve remaining issues of durability and cost for solid oxide fuel cells (SOFCs). In this study, we succeeded in fabricating a porous alloy substrate for SOFC using a Fe-Cr-Al type stainless steel, which showed excellent heat resistance. We investigated the application of the alloy substrate for the cathode side and good heat resistance and relatively low contact resistance between the alloy substrate and La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) was obtained at 700oC in air.
The Development of Sealant for Planar SOFC
Authors: Tong Jingjing , Du Xiaojia , Han Minfang
Published: October 2013

Sealing is the key technique for planar solid oxide fuel cell (SOFC). Only several sealants and sealing methods could be used for SOFC due to the extreme work conditions. Several kinds of sealants and sealing methods were summarized in this paper which emphasized glass sealing, compress sealing and composite sealing. Compositions, preparations and usages were described in the article which also gave the information of development and future direction of sealing for SOFC.
Cellular Automata Modelling of Microstructure Evolution of Ni Cermet Anode
Authors: Wang Xin , Atkinson Alan
Published: October 2013

The degradation of SOFC electrodes is largely determined by their microstructure changes. It is desirable that the microstructure evolution of electrodes in service can be simulated in 3-D for real materials so that the important parameters such as conductivities, TPB (triple phase boundary) density and tortuosity can be predicted. In this contribution a new cellular automaton based method of modelling microstructure evolution is presented. It is shown that the complex topological and morphological changes in a Ni-YSZ anode can be reproduced using this modelling method. The modelling results show that the microstructure evolution is sensitive to the wettability of Ni over YSZ. It is demonstrated that a good wettability is helpful in maintaining a slower coarsening rate and slower degradation rate of TPB density.
Characteristic Length of Oxide-Ion Conduction for Prediction of Active Thickness in SOFC Anode
Authors: Kishimoto Masashi , Iwai Hiroshi , Saito Motohiro , Yoshida Hideo
Published: October 2013

Active thickness in SOFC anodes is investigated by using one-dimensional numerical simulation. The effects of the operating conditions and the microstructural parameters of the porous anodes on the active thickness are systematically investigated. The non-linearity of the Butler-Volmer equation used for the electrochemical reaction model is found to be the key to explain the behaviour of the active thickness. The characteristic length of oxide-ion conduction is introduced by taking the ratio between the oxide-ion conductivity and the electrochemical reaction rate, which can be used as a designing parameter to predict the active thickness.
Developing 3-D Model of Intermediate-Temperature SOFC with GDC Electrolyte
Authors: Wang Lei , Jackson Gregory S. , Blackburn Bryan M.
Published: October 2013

SOFCs with GDC electrolytes present challenges for stack modeling due to the variation in conductivity and chemical activity of GDC as a function of effective oxygen partial pressure P
O2, which varies significantly down the channel in SOFC anodes with increasing fuel utilization. This paper presents a 3-D model for an intermediate-temperature SOFCs with GDC electrolytes, Ni/GDC anodes, and LSCF/GDC cathodes. The model uses fitted kinetics to capture, internal reforming and water-gas-shift in the anode as well as variations in open circuit voltage and activation overpotentials as a function of flow composition and temperature along the length of the channel. The model is validated against button cell data. The results show that for 600 and 650°C inlets, super-equilibrium concentrations of CH4 remain after 5 cm of channel. For the same fuel stoichiometry and cell voltage, humid H2 provides over 30% more power than reformate with more than 5% CH4.
First Principles Study on the Electronic Structure and Properties of Sr- and Mg- Doped LaGaO3
Authors: Wungu Triati Dewi Kencana , Sakaue Mamoru , Aspera Susan Meñez , Thuy Tran Linh Phan , Alaydrus Musa , Kasai Hideaki , Ishihara Tatsumi
Published: October 2013

The structure and electronic properties of Sr- and Mg- doped LaGaO3 was studied by employing first-principles calculations based on density functional theory (DFT) to elucidate the effect of doping and oxygen vacancy formation. The density of states analysis shows the system to be an insulator and becomes a wide gap semiconductor after the oxygen vacancy formation accompanied by emergence of a new state above the Fermi energy due to electron donation from the dopant.
First Principle Researches on Component Optimization Mechanism for the SOFC Solid Electrolyte Materials
Authors: Fang Mengya , Chen Ning , Li Fushen , Wang Lijun , Zhao Hailei
Published: October 2013

First-principle calculations based on DFT method are performed on two theoretical phase structure for potential SOFC electrolyte materials--the fluorite structure for MO2 and corundum structure for M2O3 in which M represents 3rd~6th period metal elements. The energy stability diagram of the oxides is draw, whilst the distribution trend of valence, ionic radii and oxide melting points (experimental data) for each element is obtained. Next, the bulk modulus and band structure of MO2 phase are calculated and the results are discussed combining with the structure stability trend graph. With all the results above we can discussed the relationship between the structure stability and relevant properties, and may offer some theoretic advices on the optimization of this kind of materials.
Atomistic Modeling and Ab Initio Calculations of Yttria-Stabilized Zirconia
Authors: Umeno Yoshitaka , Iskandarov Albert M , Kubo Atsushi , Albina Jan-Michael
Published: October 2013

Though a number of atomistic-model studies of yttria-stabilized zirconia (YSZ) have been reported to elucidate its properties, most of them have employed simple pairwise potential functions to express interactions between atoms, which limits the transferability of the models. We have developed a Tangney-Scandolo dipole model potential for YSZ. Energy, stress and forces on atoms calculated by the ab initio (first-principles) density functional theory are provided as reference data for potential fitting. The developed potential successfully reproduces cubic-tetragonal phase transition at a range of yttria concentration relevant with SOFC application. The potential can well reproduce the barrier energy of oxygen vacancy migration. Molecular dynamics simulations of oxygen diffusion in bulk and at grain boundaries are demonstrated.
Effect of Operational Condition on Performance and Durability of Solid Oxide Fuel Cell Fueled by Natural Gas
Authors: Aslannejad Hamed , Bozorgmehri Shahriar , Babaei Alireza , Mohebi Hamed , Ghobadzadeh amir Hosein , Haghparast Arash , Davari Sosan
Published: October 2013

The present work investigates the performance and degradation mechanisms of a Ni-based anode supported Solid Oxides Fuel Cells (SOFC) operating at 800 and 900°C on direct internal reforming of dry and wet natural gas. The catalytic properties of the anode support were first studied to determine safe conditions under which a dry conversion of the methane can occur directly within the fuel cell. A full electrochemical characterization of complete cells followed to preliminarily assess their resistance towards carbon formation when operating on direct dry-reforming. Impedance spectra have been taken every step of continuous operation to monitor the trend over the time of the different polarization contributions.
Sorbents for Bio-Fueled SOFCs
Authors: Alptekin Gokhan , Jayaraman Ambalavan , Schaefer M. , Hunt Jennifer
Published: October 2013

Unlike internal combustion engines, fuel cells operate with very high efficiency even at small scale, offering significant benefits to distributed combined heat and power (CHP) systems utilizing biowaste. However, effective utilization of biogas in a fuel cell requires removal of impurities such as sulfur and siloxanes. TDA Research Inc. (TDA) is developing a low-cost, high-capacity expendable sorbent that can remove both the H2S and organic sulfur species in biogas to the parts per billion (ppbv) levels. This sorbent bed operates downstream of a bulk desulfurization system as a polishing bed to provide an essentially sulfur-free gas to the fuel cell. The sorbent can also be modified so that it can remove contaminants such as siloxanes in a single step. TDA is carrying out field demonstrations of our integrated gas clean-up units and biofueled SOFCs. The results from the sorbent development for biogas and field demonstrations will be presented in the meeting.
Performance and Stability of High Temperature Solid Oxide Electrolysis Cells (SOECs) for Hydrogen Production
Authors: Yoon Kyung Joong , Son Ji-Won , Lee Jong-Ho , Kim Byung-Kook , Je Hae-June , Lee Hae-Weon
Published: October 2013

Solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs), which are composed of Ni-yttria-stabilized zirconia (YSZ) fuel electrode, YSZ electrolyte, gadolinia-doped ceria (GDC) interdiffusion barrier layer, and (La0.8Sr0.2)0.95Co0.2Fe0.8O3 (LSCF) air electrode, were fabricated and electrochemically tested. The performance of SOEC was dominated by the concentration polarization of the fuel electrode and activation polarization of the air electrode. The concentration polarization of the fuel electrode was reduced by optimization of the pore structure, and the eletrocatalytic activity of the air electrode was enhanced by infiltration of nanocatalysts into the porous electrodes. The cells showed excellent long-term stability up to 300 hour operation.
Carbon Deposits and Pt/YSZ Overpotentials In CO/CO2 Solid Oxide Electrochemical Cells
Authors: Yu Yi , Geller Aaron I. , Mao Baohua , Chang Rui , Liu Zhi , Eichhorn Bryan W.
Published: October 2013

Through the use of in situ ambient pressure X-ray photoelectron spectroscopy and specially designed ceria-based solid oxide electrochemical cells, CO2 electrolysis reactions (CO2 + 2e- → CO + O2-) and CO electro-oxidation reactions (CO + O2- → CO2 + 2e-) were studied on Pt and ceria electrodes supported on YSZ electrolytes. Electrolysis and electro-oxidation reactions were conducted in the presence of 0.5 Torr CO/CO2 gas mixtures at ~600 °C. When CO2 electrolysis reactions were promoted on ceria at +2.0 V applied bias, we observed the formation of graphitic carbon species on the ceria electrode surface. This carbon layer facilitates the electron conduction and extends the active region further away from the Au current collector. The charge transfer overpotentials at the Pt/YSZ interface were shown to be the largest resistance in the cell for both processes. By comparing with previous studies of the H2/H2O system, it is concluded that higher charge transfer resistances are associated with CO2 electro-oxidation and CO electro-oxidation at this three-phase-boundary.
La0.6Sr0.4Fe0.9Mn0.1O3 Oxide Cathode for the High Temperature CO2 Electrolysis Using LSGM Electrolyte
Authors: Wang Shijing , Ishihara Tatsumi
Published: October 2013

Solid oxide electrolysis cell for reducing CO2 to CO was studied by using a LaGaO3-based (LSGM) electrolyte at elevated temperature (i.e. 973 - 1173 K). Different kinds of oxide were tried as cathodes for CO2 electrolysis. It was found that LaFeO3–based perovskite material (La0.6Sr0.4Fe0.9Mn0.1O3, LSFM) shows higher activity for CO2 electrolysis with a current density of 0.76 A/cm2 at 1.6 V and 1173 K. Doping Sr and Mn to LaFeO3 is effective for improving the cathode activity for CO2 electrolysis under a reducing atmosphere, which consists of 50%CO2, 1%CO/Ar. a cell with the LSFM oxide has a high selectivity for the electrolysis of CO2 to CO.
Efficiency Calculations for SOFC/SOEC Reversible System and Evaluations of Performances of Button-Size Anode-Supported Cell
Authors: Shiraki Masahiro , Yakabe Hisataka , Uchida Hiroyuki
Published: October 2013

The energy storage efficiency of a Solid Oxide Fuel Cell and Solid Oxide Electrolysis Cell (SOFC/SOEC) reversible system was calculated. The energy storage efficiency for the SOEC mode was estimated to reach 94%-HHV. Additionally, when the system was combined with a Mg-based metal hydride, endothermic heat for water vaporization in the SOEC mode and exhaust heat in the SOFC mode can be managed efficiently to encourage the Mgbased metal hydride to absorb and desorb hydrogen gas in the reversible system. This reveals that the SOFC/SOEC is a promising system without a significant energy loss in storing energy. In addition to the numerical simulations on the energy storage performance for the SOFC/SOEC system, the I-V characteristics of a button-size anode-supported cell were also evaluated. In contrast to the SOFC mode, a larger overvoltage was observed in the SOEC mode at a high current density over 0.6 A cm-2, which was possibly caused by insufficient supply of steam. The condition of such a large overvoltage would damage the cell and indeed we found some cracks at the 8YSZ-electrolyte part after the test.