bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct Ceramic Inkjet Printing and Infiltration of Functional Coatings for Metal Supported SOFC
Authors: Tomov R I , Fakeeh A , Krishnan Venkatesan Venkata , Balasubramanian Krishnamurty , Kumar Vasant R , Glowacki B A
Published: July 2015

Direct Ceramic Inkjet Printing (DCIJP) was applied for fabrication of functional coatings in metal-supported SOFCs. An optimization procedure of the ink formulations and the printing parameters was performed allowing routine production of coatings with thicknesses below 20 µm with an additional benefit of surface defects planarization. Commercial low-cost stainless steel 430L powders were chosen as source materials. The supports sintering procedures was performed in vacuum. The density and open porosity distribution of as-sintered supports were determined by Archimedes' method and optical image analysis. The relation between the sintering conditions and the micro-structural characteristics of the metal supports and the coatings were studied. The influence of the printing parameters on the droplets spreading behaviour was explored. The microstructure and elemental distribution were investigated by Scanning Electron Microscope and energy dispersive X-ray spectrometry system. The analyses confirmed that DCIJP can be successfully applied for the production and modification of metal supported SOFCs.
Improved Performance and Durability of Anode Supported SOFC Operating on Biogas
Authors: Troskialina Lina , Dhir Aman , Steinberger-Wilckens Robert
Published: July 2015

Simulated biogas with 0.5 CO2 to CH4 ratio was used to fuel NiYSZ-based anode supported SOFC at 750oC for 22 hours. Operation on biogas was carried out after 26 hours stabilization on H2. Sn doping by infiltration technique on NiYSZ anode surface produced 4.5 times higher cell electrical performance on biogas compared to the performance of un-doped NiYSZ cell. SnNiYSZ cell showed no carbon deposited while NiYSZ cell showed 0.17mg carbon/cm2 cell. This paper presents cell electrical performance data supported by impedance spectra and mass spectra of fuel cell outlet gases. The findings in this paper may bring efforts for making biogas fuelled SOFC closer to being operable.
Electrochemical Behavior of Phosphine Induced Anode Performance Degradation in a Planar SOFC: A Numerical Study
Authors: Sezer Hayri , Celik Ismail Bektas , Yang Tao
Published: July 2015

A one-dimensional model was developed to predict the performance degradation of the SOFCs anode exposure of fuel contaminants found in typical coal syngas. This model is extended to a three-dimensional model to predict the phosphine induced performance degradation in relatively large planar cells operating on hydrogen. The model parameters are calibrated using button cell experiments conducted under accelerated tests conditions. These parameters are then used to perform simulations to predict fuel contaminant performance degradation of planar cells. The results from degradation simulations show that the contaminant coverage alter the initial current distribution, as well as the fuel and oxygen distribution inside the anode significantly. The electrochemical characteristic of the degraded cell is analyzed by performing impedance and polarization simulations at cell operating current. The polarization and impedance simulations are implemented by dividing the cell into three regions along the fuel flow direction. The results show that the degradation rates and the impedance behavior of planar cells are very different than those observed in button cells.
LSGM-based Cells for IT-SOFC Applications
Authors: Mercadelli Elisa , Sanson Alessandra , Gondolini Angela , Pinasco Paola , Basoli Francesco , Di Bartolomeo Elisabetta
Published: July 2015

Solid Oxide Fuel Cells have still many technical problems related to its high operating temperature (800–1000 °C). The most recent studies deal with reducing the operation temperature increasing at the same time the durability of the device. The use of La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) perovskite as electrolyte, could be a very promising solution for IT-SOFC operating at 600°C. In this work, LSGM bilayers constituted by a thicker porous layer (namely the anode scaffold) and a dense electrolyte were produced by tape casting. The critical issues to obtain flexible and crack-free green tapes suitable for lamination were carefully examined. In particular, the nature and amount of pore former needed to obtain an anode scaffold with a porous network suitable for the catalysts impregnation process were deeply investigated.
Investigation of Time Stability of Sr-Doped Lanthanum Vanadium Oxide Anode and Sr-Doped Lanthanum Cobalt Oxide Cathode Based on SDC Electrolyte Using SIMS
Authors: Tamm Kadi , Möller Priit , Nurk Gunnar , Lust Enn
Published: July 2015

Ceramic materials with the perovskite structure are considered as new promising alternatives to Ni-based SOFC anodes. In this study La0.7Sr0.3VO3–δ-Ce0.85Sm0.15O2–δ (SDC) anode and La0.8Sr0.2CoO3-δ-SDC cathode were fabricated by infiltration of the porous SDC scaffold with an aqueous solution of corresponding nitrates. The time stability of SOFC single cell has been studied at fixed temperatures 600 and 700°C. As a fuel the mixture of humidified hydrogen (partial pressure of 0.2) and argon (partial pressure of 0.8) has been used. During 220 h operation (at 0.6 V) the decrease in maximum power density values at both temperatures was approximately 7%. The microstructure and composition of the single cells, mostly the mobility of Sr within the cell components, before and after time stability measurements, have been analyzed using secondary ion mass spectrometry. No degradation was observed during the cell preparation process and only minor elemental mobility was seen after 24 h of operation at 700°C. However, noticeable Sr mobility has been observed after 220 h operation at 700°C.
Improvement of Protonic Ceramic Fuel Cells with Thin Film BCZY Electrolyte
Authors: Okuyama Yuji , Ebihara Noriaki , Okuyama Kenji , Mizutani Yasunobu
Published: July 2015

The performance of protonic ceramic fuel cells (PCFCs) using the thin film BaCe0.6Zr0.2Y0.2O3-δ (BCZY622) electrolyte has been studied. The reference cell with the La0.8Sr0.2MnO3-δ cathode and Ni anode showed a poor performance and short-term degradation. The overpotential of the anode and ohmic loss were the major limiting factors for degradation, and a solid solution of Ni in the BCZY electrolyte has been observed. The electrical conductivity and the proton concentration of BCZY and BCZY622 doped with 5wt% NiO were measured by an impedance analysis and thermogravimetric analysis. The electrical conductivity and the proton concentration of BCZY622 decreased by introducing NiO. To avoid a short-term degradation, the cell construction, manufacturing process, and cathode materials were improved. As a result, a carefully designed PCFC with a thin film BCZY622, Ba0.5Sr0.5Co0.8Fe0.2O3-δ
　cathode and Ni/BCZY622 cermet anode showed the good power density of 200-300mW/cm2 in the wide temperature range of 873 - 1073K , and had a stable generation.
Electrochemical MEA Characterization: Area Specific Resistance Corrected to Fuel Utilization as Universal Characteristic for Cell Performance
Authors: Kusnezoff Mihails , Beckert Wieland , Trofimenko Nikolai , Jacobs B , Dosch C , Megel Stefan , Rachau Mathias , Wieprecht Christian , Gipp Daniel
Published: July 2015

Membrane-electrode-assembly (MEA) is a main component of SOFC and defines the limits for power density, efficiency and durability available for exploitation in stacks and systems. Thus, MEA performance is a measure for possibilities of fuel cell technology. In this work the novel approach for calculation of cell performance measure based on the separation of voltage drop during the cell performance in two parts: (i) voltage drop due to change of Nernst voltage as a result of fuel utilization and (ii) voltage drop due to ohmic and polarization losses in the cell, is applied. This approach allows to eliminate the influence of non-linearity of Nernst voltage dependence on calculated cell resistance. Sorrow analysis of measured experimental data show that area specific resistance corrected for fuel conversion can be obtained from isothermal stationary operating conditions with highest accuracy and used as universal characteristic of cell performance.
Role of Lattice Strain vs. Solid Solution Doping on Atomistic near Order and Oxygen Ionic Transport for Ceria-based Micro-Energy Conversion Membranes
Authors: Shi Yanuo , Garbayo Inigo , Rupp Jennifer L. M.
Published: July 2015

Increasing the efficiencies for micro energy conversion devices based on oxygen ion conducting solid state membranes are the prerequisite toward next generations’ electrolysers and fuel cells. Here, gadolinium-doped ceria free-standing thin films are a key element i.e. for micro solid oxide fuel cells (µSOFCs). In this work, we investigate the different factors which influence ionic transport for doped ceria films with various strain states. Despite the knowledge it remains unclear what implicates more the fast oxygen ionic conductivity for ceria-based thin film membranes: How strongly does doping vs. lattice strain affect the oxygen ionic conduction and directions in free-standing film membranes for micro-energy convertors? For this, a model experiment is reported for which undoped and 20 mol%-doped ceria-based films deposited as substrate-supported and free-standing are prepared with Pt microelectrodes. We unequivocally show, that the activation energy of ionic transport is substantially increased by opposing a compressive in-plane strain on the free standing membranes (up to +Δ0.14 eV) when compared to the flat films independent on the doping level tested. The effect of lattice straining to alter the oxygen ionic transfer is more significant than the variations due to changes in the solid solution series of up to 20 mol% gadolinia in ceria for the membrane structures. Analysis of Raman shift on the F2g cationic-oxygen anionic vibration modes of pure and doped ceria confirmed a compressive strain introduced by doping. The interaction between compressive strain, dopant concentration and activation energy suggests new insights on the optimization of the micro-energy convertors.
Optimization of Tensile Strength Measurements on Glass-Ceramic Sealant Used for SOFC Stacks
Authors: Gross-Barsnick Sonja-Michaela , Babelot Carole , Federmann Dirk , Pabst Ulrich
Published: July 2015

Three different steel adaptors for the measurement of tensile strength values of glass-ceramic sealants were experimentally tested and analyzed by finite element analysis. It was shown that both the joining geometry and the adaptor design have an influence on the measured strength. An optimized adaptor design is proposed which offers a more uniform distribution of axial stresses within the sealing plane of the sample. Modelling results are compared with measured strength data. It was possible to obtain a tenfold increase of the measured strength values due to the optimization of adaptor setup and a mean fracture stress of 66 MPa was obtained for the material combination of KeraGlass ST K02 with Crofer® 22 APU.
Production and Performance of Copper-based Anode-supported SOFCs
Authors: Azzolini Andrea , Sglavo Vincenzo Maria , Downs J A
Published: July 2015

SOFCs can be produced with a copper cermet anode using similar methods used with NiO-based anodes by a one-step firing procedure at relatively low temperatures, thus having cost and high energy savings. The use of copper can allow for the use of light hydrocarbons in the cell without external reforming equipment or need of high steam to carbon ratio, and without the risk of carbon deposition in the cell
Hybrid Fuel Cells with Carbonate/Oxide Composite Electrolytes: An Electrochemical and Theoretical Insight
Authors: Ricca Chiara , Medina-Lott Bianca , Albin Valérie , Labat Frédéric , Adamo Carlo , Hinojosa Moises , Cassir Michel , Ringuedé Armelle
Published: July 2015

In view of increasing SOFCs’ lifetime, lowering the working temperature is probably the most convenient solution. The targeted range is 400-600°C, low enough to minimize the degradations kinetics while keeping rather good electrochemical performances. Carbonate/oxide composites are promising materials as electrolyte in hybrid fuel cells, which could operate at lower temperature than the usual MCFC or SOFCs. The aim of this paper is to get a deeper understanding on the origins of such improved performances by combining both experimental and modeling approaches. Experimentally, systematic studies dealing with the impact of molten salts composition, oxide phase conductivity and environmental parameters are performed by impedance spectroscopy. In parallel, Density Functional Theory calculations are carried out to provide insights into the transport mechanisms and the species involved, by first determining the most stable surface structures for both phases, separately, before building different carbonate/oxide interfaces and investigating the operating principles of these cells.
Ageing of Materials at Inlet and Outlet Fuel Manifolds in a SOFC Stack
Authors: Piccardo Paolo , Pecunia Andrea , Bongiorno Valeria , Spotorno Roberto , Wuillemin Zacharie , Ouweltjes Jan Pieter
Published: July 2015

Analyses performed on a stack operated for more than 4000h at 750°C at high fuel utilization (80%) revealed significant differences in aging behaviour of stack components when comparing fuel inlet and fuel outlet areas. Two samples were cut from the fuel inlet and outlet manifolds of the operated SOFC stack. The glass-ceramic sealing material and the interconnect alloy were exposed to a dual atmosphere (external air and internal fuel stream). The fuel composition was dry H2/N2 (60:40 vol. %) at the inlet and H2O/H2/N2 (48:12:40 vol. %) at the outlet. The stack was operated in co-flow configuration, with a large excess of air. It was found that the interfaces between the seal and the alloy were significantly affected by the difference in fuel composition. The sealant exposed to the outgoing air was significantly polluted by chromium generated in the stack and transported by the air stream. These investigations therefore reveal that the long-term evolution of the sealing and of the metallic support depends on the local conditions in the stack, as well as on additional interactions with other degradation phenomena.
Soft Sensor Design for Estimation of SOFC Stack Temperatures and Oxygen-to-Carbon Ratio
Authors: Dolenc Bostjan , Vrecko Darko , Juricic Dani , Pohjoranta Antti , Kiviaho Jari , Pianese Cesare
Published: July 2015

The life span of a solid oxide fuel cell (SOFC) stack depends on several factors, such as internal stack temperature and temperature gradients as well as the fuel gas oxygen-to-carbon (O/C) ratio. An excessive stack temperature generally accelerates the degradation, while large temperature gradients across the stack cause thermal stress, which leads to delamination. Too low O/C ratio inflicts carbon deposition, which quickly leads to stack breakage. Therefore, monitoring of these variables is of vital importance. Although direct sensing of temperatures within the stack as well as fuel gas composition in fuel stream is feasible, it is not desirable due to increased equipment cost. In this paper a data-driven design of soft sensors for minimal and maximal stack temperatures as well as the O/C ratio is presented. Dynamic and static models for stack temperature are identified from data and their performance is compared. The dynamic model is derived by means of the subspace identification, which results in a causal state-space model. The non-causal static model assumes that a combination of process variables at the stack inlet and outlet describe its internal condition. The estimator of O/C ratio is based on static relationships. The soft sensors are designed in such a way that adding extra inputs to the model yields no further increase in accuracy of the estimates. The empirical data required for modelling were obtained from a SOFC power generating unit. The results show that the reconstruction of all the relevant variables can be accomplished by simple linear regression models.
In-Situ Temperature Sensing of SOFC during Anode Reduction and Cell Operations Using a Multi-Junction Thermocouple Network
Authors: Ranaweera Manoj Prasanna , Kim Jung-Sik
Published: July 2015

Understanding in-situ temperature distribution of a SOFC stack while in operation is very important for its performance and degradation studies. The available efforts in literature are incapable of measuring the temperature of electrodes. The proposed multi-junction thermocouple network, which requires only 2N thermo-elements for N2 measuring points, can measure temperature directly from electrodes. A multi-junction thermocouple network having 9 measuring points was fabricated using K-type thermocouple wires (ϕ 0.5mm) for an in-situ measurement of the temperature distribution on a cathode (50mmx50mm, NextCell-5). The measurements were performed during an anode reduction process and during a normal cell operation while the air/fuel ratio varies. The gas temperature was measured simultaneously using a commercial K-type thermocouple from 7 mm adjacent to the cathode. The monitored cathode temperature via the in-situ sensors was directly correlated with the cell’s OCV whilst the commercial thermocouple 7mm adjacent to the electrode showed a dull change to them.
Impact of Spark Plasma Sintering Conditions on Ionic Conductivity in La1.95Sr0.05Zr2O7-δ Electrolyte Material for Intermediate Temperature SOFCs
Authors: Huo Da , Baldinozzi Gianguido , Siméone David , Khodja Hicham , Surble Suzy
Published: July 2015

To overcome the ageing issues of the solid oxide fuel cells (SOFCs), the proton ceramic fuel cells (PCFCs, also called intermediate temperature SOFCs) technology were developed, which operate at intermediate temperatures (400°-600°C). In this paper, we present the synthesis of Sr-doped lanthanum zirconate pyrochlores La1.95Sr0.05Zr2O7-δ (LSZO) that can be used as electrolyte materials. Conductivity measurements of LSZO were performed in dry and wet (5% H2O) atmospheres using electrochemical impedance spectroscopy. As the sintering processes are potential to affect not only the bulk conductivity but also the response of grain boundaries, five samples prepared under various SPS conditions were studied.
Ni-based Alloys as Protective Layer for a Conventional Solid Oxide Fuel Cell Fed with Biofuels
Authors: Lo Faro Massimiliano , Trocino Stefano , Campagna Zignani Sabrina , Machado Reis Rafael , Monforte Giuseppe , Ticianelli Edson A. , Aricò Antonino S.
Published: July 2015

A possible scenario for the future is the utilization of alternative fuels especially those obtained from renewable sources including those derived from biomass. One of the main implications is regarding the consumer’s ability to use an increasingly diverse selection of energy sources. Small fuel cells systems, typically less than 10kW, are under consideration for many applications that traditional electric utilities have not supplied widely. In this area, solid oxide fuel cells (SOFCs) may enable new companies to enter the power-generation business as equipment providers or heat and electricity providers. The most common type of SOFC is based on Ni-YSZ as anode and operates at temperatures above 700 °C using H2 or syngas (H2 + CO) produced from a reforming process (internal or external). In this communication, we report the preparation and electrochemical characterization of catalysts having proper behaviour for the utilization as protective layer for the anode.
Performance of Protonic Ceramic Fuel Cell with Thin Film Yttrium Doped Barium Zirconate Electrolyte
Authors: Bae Kiho , Jang Dong Young , Noh Ho-Sung , Kim Hyun Joong , Hong Jongsup , Yoon Kyung Joong , Kim Byung-Kook , Son Ji-Won , Shim Joon Hyung
Published: July 2015

In this work, anode-supported protonic ceramic fuel cell (PCFC) with thin yttrium doped barium zirconate (BZY) is fabricated using pulsed laser deposition (PLD). For highly dense and thin electrolyte film growth, anode functional layer and anode interlayer are deposited on porous anode support by electrostatic slurry spray deposition and PLD, respectively. As a result, high open circuit voltage of 0.98 V is obtained after anode reduction at 600 oC, indicating that the fabricated BZY electrolyte effectively blocks gas permeation. Electrochemical performance of the PCFC is obtained with peak power densities of 55‒171 mW/cm2 at an operating temperature regime of 450‒600 oC.
Electrochemical Synthesis of Ammonia with Proton Conducting Solid Electrolyte Fuel Cells at Intermediate Temperatures
Authors: Otomo Junichiro , Noda Naoto , Kosaka Fumihiko
Published: July 2015

The electrochemical synthesis of ammonia using solid electrolyte fuel cells with proton conducting solid electrolyte, yttrium-doped barium cerate, was investigated at intermediate temperature (around 500°C). Ru-based electrode catalysts consisting of a mixed ionic-electronic conductor containing Ru active sites, i.e., electrode catalysts with highly dispersed Ru nanoparticles on a lanthanum strontium titanate support, were synthesized. Pd-based catalyst (AgPd) was also examined for comparison. A two-electrode configuration was used with a dynamic hydrogen electrode as the counter electrode. Ammonia formed on the working electrode through reaction of nitrogen with protons diffused from the counter electrode with Ru- and Pd-based catalysts. The ammonia production rate was influenced by the electrode potential; it was maximum at -500 to -1000 mV. The faradaic efficiency of ammonia formation with Ru-based catalyst was 2%, whereas that with Pd-based catalyst was lower than 1%. Highly dispersed Ru active sites may contribute to improving the faradaic efficiency.
Protective Coating from Manganese Cobalt Oxide Powders Obtained By High Energy Ball Milling: Materials Characterization and Cell Environment Testing
Authors: Masi Andrea , Bellusci Mariangela , Carlini Maurizio , McPhail Stephen J. , Pumiglia Davide , Reale Priscilla , Rinaldi Antonio , Padella Franco
Published: July 2015

The required application of ceramic coatings on metallic interconnects to avoid corrosion in SOFC oxidizing environment has pointed out the need to find cheap and environmental friendly approaches for the production of coating powders, to be applied by diffused and cost effective wet powder processing techniques like spray and slurry coating methods. High Energy Ball Milling (HEBM) is a mechanochemical powder processing technique here exploited to produce mixed composition coating precursor powders from Mn and Co oxides. The processed compound consists in nanostructured and intimately mixed Mn-Co oxides that rapidly react to produce the high temperature spinel phase during the sintering process. A slurry suspension was formulated and applied on a stainless steel substrate, evaluating the coating behaviour during 500h oxidation test at 800°C by means of Area Specific Resistance (ASR) evolution, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses.
Utilisation of Coal in Direct Carbon Fuel Cells
Authors: Irvine John , Fuentes Cuesta Aida , Mottram Andrew , Jiang Cairong , Savaniu Cristian , Jain Sneh
Published: July 2015

Hybrid Direct Carbon Fuel Cells merge Solid Oxide Fuel Cell (SOFC) and MCFC technologies, using a solid oxide electrolyte to separate the cathode and anode compartments, while a molten carbonate electrolyte is utilised to extend the anode/electrolyte region. Oxygen is reduced to O2- ions at the cathode and transported across the solid electrolyte membrane to the anode compartment, where carbon is oxidised to CO2. Molten carbonate could enhance the carbon oxidation in two ways as a fuel carrier or as an electrochemical mediator. The maximum energy density can be achieved by fully oxidising carbon to CO2 offering very high efficiencies. This concept has been demonstrated using a wide range of carbons and carbon-rich fuels such as coal, plastics, carbon colloids, activated carbons and charcoals. In a short stack of 3 cells delivered a maximum power output at 650oC of 5.4 W, at over 100mWcm-2.The underlying chemical processes in DCFCs are complex involving a series of catalytic and electrochemical reactions of a complex fuel. Coal and biochars are quite far from pure carbon comprising of high hydrogen content and often significant oxygen, sulphur and nitrogen contents as well as inorganic, ash components. Here we report on the pyrolysis and oxidation reactions and processes that occur in situ and in DCFC relevant conditions. Of key importance is interplay between carbon and its oxides as direct oxidation of carbon to carbon dioxide delivers the ultimate efficiency. There is a change in process above 750oC where the reverse Boudouard reaction becomes dominant.
Direct Coal Oxidation in Modified Solid Oxide Fuel Cells
Authors: Deleebeeck Lisa , Gil Vanesa , Ippolito Davide , Campana Roberto , Hansen Kent Kammer , Holtappels Peter
Published: July 2015

Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate slurry or anode layer. The nature of the coal affects both open circuit voltage and power output. Highest OCV and power densities were observed for bituminous coal and by adding manganese oxide or praseodymium-doped ceria to the carbon/carbonate mixture. Comparing the carbon black fueled performance of an anode supported (315 µm anodes) and cathode supported cell (15 µm anode) indicates a superior performance of the latter. Using un-catalyzed biomass (charcoal) as fuel results in an OCV of 941 mV and a maximum power density of 78 mW/cm2 at 755ºC similar to the power output of manganese oxide catalyzed bituminous coal (73 mW/cm2).
Electrolyte Stability in Direct-Carbon Fuel Cells with Molten Sb Anodes
Authors: Oh Tae-Sik , Zhou Xiaoliang , Vohs John M. , Gorte Raymond J.
Published: July 2015

The long-term stability of direct carbon fuel cells with oxygen ion conducting solid electrolytes and molten Sb anodes has been examined. We have investigated previously observed etching phenomenon as a function of the electrolyte composition and cell operating conditions. We conclusively show that electrolyte etching is not electrochemical in nature, but rather results from chemical reaction between the electrolyte and Sb2O3 that is produced during cell operation. Chemical reaction tests also support this conclusion.
Introducing Anode Fluidization into a Tubular Liquid Antimony Anode Direct Carbon Fuel Cell
Authors: Cao Tianyu , Shi Yixiang , Cai Ningsheng
Published: July 2015

A bench scale direct carbon fuel cell unit was assembled based on an electrolyte supported tubular SOFC (Solid Oxide Fuel Cell). The system adopted liquid Sb as anode and was operated at 800oC to evaluate the electrochemical performance of the direct carbon fuel cell. Fluidization gas was introduced into the fuel cell and the liquid Sb anode worked under two working conditions: fixed bad and fluidized bed, and the effects of fluidization on fuel cell performance were investigated. De-ash coal was also introduced into anode chamber in both of these two ways, the fuel cell performance was promoted by coal addition and fuel supplied by fluidized bed exhibited better performance. The experimental results also approved the potential of continuous operation of the direct carbon fuel cell system.
The Fate of Phosphine in SOFC Fuels
Authors: Finklea Harry O. , Zhang Wei , Jony Mahfuzur , Demirgok Berk
Published: July 2015

Phosphine (PH3) is present in part-per-million levels of coal syngas, a potential fuel for SOFCs. Previous studies have shown that the SOFC loses power and ultimately fails during prolonged exposure to ppm levels of phosphine in wet and dry fuels. A mass spectrometer was used to analyze fuel gases after passing the gases through a heated tube or after passing the gases across the anode of an operating SOFC. Phosphine appears to react with residual oxygen at intermediate temperatures in dry hydrogen, but does not react above 600ºC. At higher water concentrations, phosphine reacts at temperatures above 400ºC. Phosphine is detected in the exhaust gas of a SOFC using dry hydrogen while at open circuit, and disappears from the exhaust gas during current flow. No new compounds containing phosphorus were detected in the m/z range of 45-100, eliminating P2, HPO, HPO2 and HPO3 as possible reaction products.
Impedance Spectroscopy Studies of the Behavior of MoNi-CeO2 Anode in SOFC Using H2S-Containing Hydrogen as Fuel
Authors: Escudero Maria Jose , Gómez de Parada Ignacio , Fuerte Araceli
Published: July 2015

In this study, the effect of H2S on the cell performance for a SOFC cell of MoNi-Ce/LDC/LSGM/LSFC has been investigated under different concentrations of H2S (0-500 ppm) at 750, 800 and 850 ºC using IV, IS and load demands. The maximum power density decreases with increasing H2S concentration and the reduction of temperature. However, the cell performance remained stable when was demand a load during 1 h in all tests studied. The impedance spectra revealed three distinct rate limiting processes. The high frequency arc is not affected by the H2S concentrations and could be attributed to oxygen ions transfer between the TPB and electrolyte. The intermediate frequency arc is the most sensitive to the anode atmosphere and appears to be associated with the sulphur poisoning process. While the low frequency arc became significantly at high concentrations of H2S (> 50 ppm) then it could be related with gas phase diffusion.
Development of a Direct Ammonia Fueled Hydrogen Membrane Fuel Cell
Authors: Aoki Yoshitaka , Kobayashi Syohei , Tsuji Etsushi , Habazaki Hiroki
Published: July 2015

Hydrogen membrane fuel cells, HMFC, were fabricated by RF sputtering deposition of BaCe0.8Y0.2O3-

d
thin films on Pd solid anode. The HMFC can give OCF of 1.1 V and peak power density of 300 mW cm-2 at 600°C with H2 fuels. On the other hand, the direct NH3 fuel HMFC reveals OCV of 0.95 V and peak power density of 80 mW cm-2 at 600°C. The impedance spectroscopy reveals that anodic polarization is a main contribution to the loss in HMFC.
Mechanism and Activity of Ni-Based (Ni-M: M = Fe, Mo, W, Ta) Cermet Anodes for Ammonia Oxidation in SOFCs
Authors: Hashinokuchi Michihiro , Yokochi Ryuji , Akimoto Wataru , Doi Takayuki , Inaba Minoru , Kugai Junichiro
Published: July 2015

We investigated the activity for Ni-based (Ni-M: M = Mo, W and Ta) anodes for ammonia oxidation in SOFCs. It was found that Mo was the most effective additive for the anode cermets in this study. It was found that the activity for ammonia oxidation at Ni-Mo anode was determined by a balance between ammonia adsorption and nitrogen desorption, and synergetic effects of Ni and Mo improved the anode activity for NH3 oxidation.
Effects of Nitride Formation on Anode Catalytic Activity in Ammonia-Fueled SOFCs
Authors: Yokochi Ryuji , Hashinokuchi Michihiro , Doi Takayuki , Inaba Minoru
Published: July 2015

Four kinds of anodes, Ni-Mo(3%)/, Ni-W(3%)/, Ni-Ta(3%)/ and Ni-Nb(3%)/Sm0.2Ce0.8O2 (SDC) were prepared by impregnating Mo, W, Ta and Nb precursor solutions into pre-sintered Ni/SDC cermets. Their anode performance was evaluated in ammonia-fueled SOFCs at 973-1173 K to clarify the correlation between nitride formation and anode activity. The addition of Mo, W and Ta enhanced the anode activity for NH3 oxidation, but Nb did not. Under the operation conditions (i.e. at 973-1173 K in NH3), MoO3, WO3 and Ta2O5 reacted with NH3 to form nitrides (Mo2N, W2N and TaON), but Nb2O5 did not. These results suggest that the easiness of the nitride formation is closely related to the high activity anode for NH3 oxidation.
Electrochemical and Catalytic Behavior of Ni-Based Cermet Anode for Ammonia-Fueled SOFCs
Authors: Molouk Ahmed Fathi Salem , Yang Jun , Okanishi Takeou , Muroyama Hiroki , Matsui Toshiaki , Eguchi Koichi
Published: July 2015

In this work, a conventional solid oxide fuel cell, Ni‒YSZ|YSZ|LSM, was prepared and the mechanism of electro-oxidation of ammonia over Ni‒YSZ anode was studied. Especially, we focused on the correlation between the catalytic activity of anode for ammonia decomposition and cell performance. This systematic investigation has revealed that ammonia is catalytically decomposed into H2 and N2, and then H2 produced is electrochemically oxidized over anode. Furthermore, the operating temperature and hydrogen concentration had a great impact on ammonia decomposition as well as cell performance. These results provided the strategy for the development of anode materials for direct ammonia-fueled SOFCs.
Syngas-fed SOFCs: Analysis of Performance Sensitivity to Fuel Composition
Authors: Baldinelli Arianna , Barelli Linda , Bidini Gianni
Published: July 2015

In the outlook of clean and efficient power production, Solid Oxide Fuel Cells (SOFCs) are a promising technology. Unlike other fuel cell technologies, SOFCs can be run on many fuel types, included RES-derived gases. Many synthesis technologies exist, yielding syngas with different compositions. In addition to that, syngas composition is influenced by some other factors (heterogeneous feedstock, process variables fluctuation). Hence, it is interesting to investigate the fuel composition effect on SOFCs performance. The present study follows a previous work of the authors concerning the development of a black box model for SOFC performances forecast basing on fuel composition. Therefore, this study aims at broadening the applicability range of the model to fuel mixtures exhibiting a wider composition variability. All data used for the model development come from experimental activity.
Low Temperature Methane Steam Reforming for SOFC
Authors: Sun Jie , Li Ji Gang , Zhu Yue Feng , Zhang Jing Jing , Zhou Tian , Li Li , Wang Yu Guang , Liu Shuai , Jiang Zhi Gang , Dong Zhong Chao , Sun Chun Wen , Li Hong , Chen Li Quan
Published: July 2015

The properties of flowerlike microspheres ceria based nickel catalyst for low temperature methane steam reforming (SMR) were studied. The ceria microspheres were prepared by hydrothermal method. Catalyst of nano-sized nickel oxide particles based on flowerlike cerium oxide microspheres with high disperse were prepared to achieve simultaneous dehydrogenation of methane and water molecules on multi-active sites. The catalyst was characterized by means of Scanning Electronic Microscope (SEM), X-ray diffraction (XRD). Results showed that this special catalyst NiO/CeO2 had high activity and stability for SMR reaction below 600oC. The stability of the catalyst reached more than 1000 hours. The conversation of methane under 590oC was above 90%. The tests of the influence of different H2O/CH4 mole ratios on activity and selectivity of catalyst showed that 1.5~2.5 ratios was an ideal choice. During the running of micro-tube methane steam reformer with this catalyst, the methane conversion of 556oC kept over 25mol.%.
Performance of SOFC Power Unit Assisted by Paper-Structured Catalyst
Authors: Shiratori Yusuke , Sakamoto Mio , Tran Quang Tuyen , Uchiyama Yasuyuki , Uchiyama Naoki
Published: July 2015

Paper-structured catalyst (PSC) is a flexible catalyst material composed of inorganic fiber network loaded with metal catalyst which can be applied into cell stack to assist hydrocarbon reforming. Catalytic performance of PSC was considerably improved by the dispersion of Mg-Al hydrotalcite (HT) in the inorganic fiber network because of the formation of fine Ni particles and suppression of Ni loading on the inorganic fiber (SiO2-Al2O3) to cause coking. High temperature SOFCs can convert chemical energy of a fuel directly to electricity even in the feed of low calorie gas. The use of engine-exhaust, which contains unburned hydrocarbons, H2 and CO, as a fuel for SOFC is promising idea. Recently, a compact SOFC unit operated by the direct feed of engine-exhaust was developed by Atsumitec Co., Ltd. However, performance of the unit can easily deteriorate, unless the fuel is homogeneously supplied into the unit in which several numbers of stacks were arrayed. This study demonstrated that insertion of the HT-dispersed PSC into the real SOFC stack led to large increase in the unit performance because PSCs can boost up the output power of stacks placed at the positions where fuel is not well supplied.
CeO2 - ZrO2 Catalysts for the Use of Biogas in IT-SOFC
Authors: Pappacena Alfonsina , Graziutti Rafael , Boaro Marta , Trovarelli Alessandro
Published: July 2015

Ce0.8Zr0.2O2 and Ce0.8La0.5Nd0.2Zr0.13O2-x, were prepared with a surfactant assisted approach and impregnated with different amounts of nickel. The catalysts were studied in the dry reforming reaction with the aim of using them in a biogas fuelled IT-SOFC anode. The oxidative dry reforming reaction was also investigated, finding that small amounts of oxygen in the biogas mixture reduce the effect of dry reforming side reactions. Catalysts containing Lanthanum and Neodymium showed an improved activity at 600 °C and 650 °C in terms of H2 selectivity and carbon resistance.
Infiltrated La0.8Sr0.2Ga0.8Mg0.2O3-δ Based Cells Fed with Biogas
Authors: Di Bartolomeo Elisabetta , Luisetto Igor , Basoli Francesco , Zurlo Francesca , Salehi Zahra , Licoccia Silvia
Published: July 2015

La0.8Sr0.2Ga0.8Mg0.2O3-
d (LSGM) based porous/dense structures were optimized for infiltration of different metal catalysts. A solution of metal (Ni, Co, Cu and their 1:1 mixtures) salts was used for infiltration. Multiple infiltrations were necessary to get enough metal catalyst amount to get performing electrocatalytic performance. For the initial catalyst screening, ex-situ catalyst activity measurements were performed on impregnated LSGM powders with the same amount of metal catalyst infiltrated in the scaffolds. Electrochemical measurements were performed on infiltrated cells with the same amount of Ni and Ni-Co in the temperature range between 650 and 750°C and the results discussed and compared with catalytic measurements.
Electrochemical Impedance Study of Ag/Cu-Ca0.2Ce0.8O2+δ Anode for SOFCs Operating with Simulated Biogas
Authors: Fuerte Araceli , Escudero María José
Published: July 2015

The effect on electrochemical properties of adding dopant levels of silver into solid oxide fuel cell anodes based on ceria has been examined. Physicochemical characterisation and electrical properties in reducing atmosphere as well as thermal and chemical compatibility with LSGM electrolyte were first investigated. Two symmetric cells with copper doped ceria (Cu-CaCe) and silver-copper doped ceria (AgCu-CaCe), reference and examined anode respectively, on LSGM electrolyte were prepared and tested. Electrochemical impedance spectroscopy (EIS) has been used to determine the electrochemical properties of these anodes in the temperature range of 723–1023 K under hydrogen and methane and three simulated biogas mixtures at 1023 K. Material exhibits excellent thermal and chemical compatibility with LSGM electrolyte and the introduction of silver in the anode composition improves the electrochemical properties of material. Therefore, AgCu-CaCe anode is an attractive option for direct-biogas solid oxide fuel cells.
The Impact of Toluene on the Performance of Anode-Supported Ni-YSZ SOFC Operated on Hydrogen and Biosyngas
Authors: Madi Hossein , Diethelm Stefan , Ludwig Christian , Van herle Jan
Published: July 2015

This paper presents an experimental study of the impact of toluene on the performance of anode-supported (AS) Ni/YSZ SOFC operating at ~800 °C, 0.25 A/cm2 fed with H2 and biosyngas. Toluene was added to the fuel stream and its concentration increased from tens to thousands of ppmv. Each poisoning test was followed by a recovery step. The main goal of this work is to define a concentration threshold of toluene as a model tar compound and to identify the degradation mechanism caused by this tar compound. Polarization behavior, IV and electrochemical impedance spectroscopy (EIS) were analyzed to evaluate the cell performance. A linear degradation is observed at concentrations above 1000 ppmv for the cell which was fed with H2. The degradation was due to local C(s) deposition. By contrast, toluene even up to 3500 ppm did not cause an increased degradation when the cell was fed with reformed biosyngas.
Octane Steam Reforming and Electrochemical Reaction on Cu-GDC Cermet Anode of Internal Reforming Solid Oxide Fuel Cell
Authors: Tomomichi Keita , Kinoshita Masahiro , Yamagami Shun , Yamada Yuki , Terai Takayuki , Sasaki Kazuya
Published: July 2015

A porous cermet of Cu and gadolinium oxide-doped ceria (Cu-GDC), which, respectively, have excellent sulfur tolerance and oxygen ion supply property, was focused as an anode electrode for the octane-direct use SOFC. Influences of operating conditions, steam/carbon ratio and cell temperature, on the steam internal reforming reaction and electrochemical reaction on the Cu-GDC cermet anode electrode were investigated. In order to understand the influence of difference in branching of carbon chain, n-octane (linear alkane) and iso-octane (branched chain alkane) were used. By raising the S/C ratio, the carbon deposition is decreased but the fluctuation range of the OCV is increased. Mainly H2, CO, CO2, CH4, and C2H6 are generated in the reforming reaction of n-octane, and C3H8, CH3OH, and C4H10 are also generated in addition to those in the reforming reaction of iso-octane. By using the n-octane fuel, the carbon deposition is reduced. The rate-determining process is dissociation to H2 and CO.
Cracking Reaction of Octane Fuel and Electrochemical Reaction on Ni-YSZ Cermet Anode of Internal Steam Reforming Solid Oxide Fuel Cell
Authors: Kinoshita Masahiro , Tomomichi Keita , Yamagami Shun , Yamada Yuki , Terai Takayuki , Sasaki Kazuya
Published: July 2015

A porous cermet of Ni and yttria stabilized zirconia (Ni-YSZ) cermet was used as an anode electrode for the octane-direct use SOFC. Influences of operating conditions, steam/carbon ratio and cell temperature on the steam internal reforming reaction and electrochemical reaction on the anode electrode were investigated. In order to understand the influence of difference in branching of carbon chain, n-octane (linear alkane) and iso-octane (branched chain alkane) were used. By the internal steam reforming of n-octane, H2, CO, CO2, CH4, and C2H6 are generated. The reforming rate of n-octane is large, while the reforming of iso-octane is slow reaction. When the fuel utilization is low, H2 and CO preferentially contribute for the power generation. The carbon deposition rate is quite large, although the initial power generation performance is high. Especially, the carbon deposition is remarkable when iso-octane is used as the fuel.
Electrochemical Investigation of a Large SOFC Fed with n-Dodecane Reformate
Authors: Trocino Stefano , Lo Faro Massimiliano , Campagna Zignani Sabrina , Monforte Giuseppe , Aricò Antonino S.
Published: July 2015

Solid oxide fuel cells (SOFCs) have been extensively studied due to their potentiality for clean and efficient power generation. Recently, SOFCs coupled with an external reforming have been suggested for the utilization in marine on-board applications. Diesel marine is the conventional fuel actually used; however, the stability of a conventional SOFC fed with a diesel reformate is not yet proven. Furthermore, the testing of a large area SOFC has a specific importance with the aim of the subsequent scaling up to a stack. This study deals with the investigation of the reliability and feasibility of a SOFC fed with syngas from n-dodecane. The SOFC consisted of Ni-YSZ/YSZ/YDC/LSFC, whereas the reformer catalyst was based on Rh-CeO2-ZrO2.
Direct Ethanol Anode-Supported Solid Oxide Fuel Cell
Authors: Nóbrega Shayenne D. , Steil M. C. , Georges Samuel , Uhlenbruck Sven , Fonseca Fabio C.
Published: July 2015

An anode-supported solid oxide fuel cell (SOFC) was continuously operated with direct (anhydrous) ethanol for ~600 hours, with a high current density. The operation of the SOFC under ethanol was made possible with the deposition of a ceria-based catalytic layer onto the cermet anode support, which efficiently converts the primary fuel in hydrogen. The catalytic layer associated with the gradual internal reforming (GIR) process avoids carbon deposition on the Ni surface. The results provide a significant advance towards the development of direct ethanol solid oxide fuel cells.
3D Multiscale-Multiphysics SOFC Modelling Status at the Institute of Electrochemical Process Engineering, FZ Jülich
Authors: Peksen Murat , Al-Masri Ali , Peters Roland , Blum Ludger , Stolten Detlef
Published: July 2015

The Institute of Electrochemical Process Engineering (IEK-3), SOFC modelling research group has been giving particular attention to the 3D multiscale-multiphysics modelling of SOFC systems during the last seven years. Focus has been the coupled thermochemical fluid flow and thermomechanical interactions of SOFCs, auxiliary components, as well as complete fuel cell systems. Currently, emphasis of research has been given to the material, process and 3D design optimisation of APU fuel cell stacks, micro modelling of cells and the full scale high-end 3D system level multiphysics modelling and optimisation. Therby, an important investigation field has been the various geometrical component scales, including macro, meso, and micro level by coupling the experimentally validated numerical predictions from system level down to the component and cell level. Coupled CFD/FEM is used to predict the thermochemical fluid flow, heat radiation, electrochemical and species transport, creep deformation, elastoplasticity and cyclic behaviour.
Simulation and Prediction of 3-D Microstructural Evolution and Long Term Performance of Ni-YSZ Anode
Authors: Wang Xin , Atkinson Alan
Published: July 2015

The electrochemical performance of SOFCs degrades over the operation time and a major contributor is microstructure coarsening in the anode. To enable long term durability prediction and improve the anode performance, it is necessary to understand its microstructural evolution under different operation conditions. In this contribution, we demonstrate that the 3D real microstructure evolution of a Ni-YSZ anode can be simulated and predicted using a cellular automaton approach. The same modelling approach is also used to determine the wettability of Ni on YSZ in the real anode. The 3D microstructures of as-reduced and aged anodes were reconstructed experimentally using the focused ion beam (FIB) slice and view method and it is shown that the simulation agrees well with the experimental results. Using these short time experimental observations as a calibration of the model, the long term microstructure evolution of the Ni-YSZ anode and its long term performance and lifetime are predicted.
Systematic Modeling for Triple Phase Boundary of Ni/ZrO2 SOFC Anode from First Principles
Authors: Tada Tomofumi
Published: July 2015

Density functional calculations of Ni/ZrO2 triple phase boundary (TPB) were carried out, and a systematic modeling for atomic TPB model was proposed. Ni-slab based TPB and Ni-cluster based TPB models were constructed according to the systematic modeling and used for electronic structure calculations. It is found that Ni-slab based TPB is more suitable than Ni-cluster based TPB for the reasons that 1) the electronic states of Ni in the Ni-slab based TPB are almost comparable to those of Ni bulk, whereas those in the Ni-cluster based TPB are clearly different from those of Ni bulk, and 2) calculated reaction energies in oxygen spillover with Ni-slab based TPB are almost insensitive to the thickness of Ni-slab, whereas those with Ni-cluster based TPB shows scattered reaction energies depending on the number of Ni atoms in the cluster and the shape of the cluster.