bluuebunny/crossref_metadata_2025 huggingface dataset:
Development and Manufacturing of SOFC-Based Products at SOFCpower SpA
Authors: Bucheli Olivier , Bertoldi Massimo , Modena Stefano , Ravagni Alberto
Published: October 2013

SOFCpower SpA provides efficient energy solutions based on its proprietary planar SOFC technology. The company focuses on products that use natural gas either for heat and power generation (CHP) or for distributed power generation at high electrical and total efficiencies. The company develops and manufactures SOFC power modules in close collaboration with both European heat appliance OEMs and utilities. With several years of operational experience in running its pilot plant in Italy, SOFCpower has consolidated its manufacturing know-how and capabilities and has confirmed the competitiveness of its products, capable to match target market requirements and being sold and operated with grid parity prices. Collaboration with Industrial component suppliers and integrators has largely increased in intensity within the last 2 years, key success factor for reaching the required cost and reliability targets for the stationary market. First units have been installed since 201, operating as sheltered field tests in the North-East of Italy within the frame of the Crisalide Initiative. Those activities will be strongly enlarged with the participation in the FCH-JU demonstration project ENE.FIELD started in October 2012. SOFCpower is also involved on strategic development activities to demonstrate the added value of its product for different applications including high temperature electrolysis (HTE), biogas and waste-to-energy (WTE) applications. The paper provides an update of the stack and system development, including operational results of SOFC-based micro-CHP and the approach to enter the distributed cogeneration market.
Development of a New Concept SOFC at Murata
Authors: Tomoshige Yosuke , Mori N. , Iha M. , Takada T. , Konoike T.
Published: October 2013

Murata Manufacturing Co., Ltd. has been developing a new concept, planar-type solid oxide fuel cell (SOFC) fabricated using a single-step co-firing process. Each cell consists of an electrolyte, electrodes, current collectors, gas-separators with manifolds, and gas-flow channels. The membrane electrode assembly (MEA) is sandwiched between ceramic gas-separators with via-hole electrodes providing electrical paths between cells. Only two steps are required to assemble cells: first, a green state glass-ceramic is placed around the manifold area to provide gas separation; second, a conducting material is applied to the electrode area to provide electrical connection between neighboring cells. The single cell manufacturing and stack assembling methods are described in detail here and represent a promising means for overcoming problems common to planar-type SOFCs.
SOFC System Using a Hot Gas Ejector for Offgas Recycling for High Efficient Power Generation from Propane
Authors: Dietrich Ralph-Uwe , Lindermeir Andreas , Immisch Christoph , Spieker Carsten , Spitta Christian , Stenger Sebastian , Leithner Reinhard , Küster Torben , Oberland Alexander
Published: October 2013

Solid oxide fuel cell (SOFC) systems using anode off-gas and process heat for endothermic fuel reforming promise outstanding system efficiency for power generation from hydrocarbon fuels. A project team of four research institutions developed a stand-alone and thermally self-sustaining SOFC system with 830 Watt gross power and 54 % electrical system efficiency (gross, based on fuel LHV). A commercially available integrated stack module (Staxera ISM) of sunfire GmbH (Dresden, Germany) was used as SOFC.
An Innovative SOFC Hybrid Based Prime Supply for Telecom Applications
Authors: Ferraro Marco , Brunaccini Giovanni , Napoli Giuseppe , Sergi Francesco , Dispenza Giorgio , Randazzo Nico , Antonucci Vincenzo
Published: October 2013

Telecom companies worldwide are investigating the option of producing the power needed onsite with fuel cells, while staying grid-connected to use the grid, where available, as backup power in case of an emergency only. Among the available technical options, DC based backup power systems have had huge success in telecom markets, thanks to the higher efficiency than the AC power systems, because of fewer conversion cycles required for energy storage. The proposed work assesses a natural gas operated SOFCNa- NiCl2 battery hybrid system, both electronically and thermally integrated. A hybrid system combining a 0.5 kW SOFC and a 4.5 kW Na-NiCl2 has been experimentally evaluated.
2-D Simulation of Heat and Mass Transfer Effects on Charge/Discharge Characteristics of a Solid Oxide Redox Flow Battery
Authors: Ohmori Hiroko , Iwai Hiroshi
Published: October 2013

A time-dependent 2-D numerical simulation was performed on a solid oxide redox flow battery (SORFB) in order to reveal the fundamental characteristics of this new system. SORFB is a rechargeable battery consisting of solid oxide electrochemical cell (SOEC) and redox metal. The simulation considers heat and mass transfer in the system taking both electrochemical and redox reactions into account. The numerical results clearly showed the time-dependency of the thermal field, particularly in discharge operation. The spatial and temporal changes of temperature field associated with the change of the current density distribution were results of combined effects of heat generation/absorption by the electrochemical and redox reactions and heat release by air convection. It was also found that the active reaction region in redox metal evolutes with time. Since these physical quantities affect the battery performance, the heat transfer and gas diffusion should be carefully designed.
Power-To-Storage - The Use of an Anode-Supported Solid Oxide Fuel Cell as a High-Temperature Battery
Authors: Menzler Norbert H. , Hospach Andreas , Niewolak Leszek , Bram Martin , Tokariev Oleg , Berger Cornelius , Orzessek Peter , Quadakkers Willem J. , Fang Qingping , Buchkremer Hans Peter
Published: October 2013

A novel high-temperature energy storage system based on an SOFC is presented (Power-to-Storage). The energy is stored as a metal/metal oxide which is part of the fuel side. However, in contrast to a classical SOFC, the fuel side is kept under stagnant hydrogen/water vapor. By using the cell as an electrolyzer (SOEC), the surplus electricity (from renewable energy sources) is used to charge the system by reducing a metal oxide. Vice versa, if energy is needed the system works as an SOFC thereby oxidizing the metal (discharging the battery). First results from storage material development and stack testing are presented.
300 W SOFC-Generator with Endothermic Reforming of Propane and Other Innovative Concepts
Authors: Szepanski Christian , Lindermeir Andreas , Dietrich Ralph-Uwe , Stenger Sebastian , Leithner Reinhard , Deichmann Richard , Dörrer Lars , Borchadt Guenter
Published: October 2013

Within the network of the Lower Saxony SOFC Research Cluster, a highly efficient SOFC power generator has been built. Its purpose is to supply 12 V (DC) devices and charge lead-batteries for off-grid applications, such as mobile homes or radio masts. The system is based on the Mk200 stack of Sunfire GmbH, Dresden and includes multiple innovative approaches for improved efficiency and stability.
Understanding the Electrochemical Behavior of SOFC Stacks
Authors: Lang Michael , Klein Miriam , Henke Moritz , Willich Caroline , Schiller Guenter , Hauler Felix
Published: October 2013

In contrast to single cells the electrochemical processes, the resistances and the loss mechanisms of SOFC stacks are not well understood. The paper presents both experimental and modeling results of the electrochemical behavior of SOFC stacks with ASC cells in the cassette design at different operating conditions. The focus lies on the investigation of critical operating conditions, e.g. high current densities and high fuel utilizations. The stacks were investigated by current-voltage curves, electrochemical impedance spectroscopy (EIS) and gas analysis. Results of both integral and locally resolved measurements along the fuel gas flow path are presented. The modeling results were obtained with a two dimensional elementary kinetic model which represents a single cell along the gas channels and through the thickness of the membrane-electrode assembly.
Temperature Effect Due to Internal Reforming in Pressurized SOFC
Authors: Willich Caroline , Tomaszewski Amrei , Henke Moritz , Kallo Josef , Friedrich K. Andreas
Published: October 2013

For the integration in a hybrid power plant the behavior of pressurized SOFC stacks was examined. A detailed electrochemical model was validated allowing for a thorough interpretation of experimental data. This contribution focuses on the use of reformate gases and the influence of internal reforming. Experimental and simulated current-voltage characteristics and electrochemical impedance spectra were used to examine the temperature differences due to internal reforming which were found to have a major impact on performance. It is shown that similar performance can be obtained for different fuel gas compositions if temperature within the stack is controlled.
Steady State Analysis of 5kW SOFC System with Novel Configuration
Authors: Jiang Jian Hua , Li Xi , Yang Jie , Li Jian
Published: October 2013

For stand-alone solid oxide fuel cell (SOFC) systems, delivering demanded power, maintaining system operating constraints, and achieving high system efficiency are the primary design objectives. We consider a novel SOFC design that includes an air bypass valve to achieve greater controllability. Through model-based analysis, the steady-state system performance is investigated. And the optimal operating points (OOPs) for different loads are explored to achieve the high system efficiency. The effects of bypass valve are quantified. The analysis demonstrates that the design is feasible and the bypass valve can play a substantial role on improving the overall system performance and operationability.
Testing Micro-Tubular SOFCs in Unmanned Air Vehicles (UAVs)
Authors: Meadowcroft Antony D , Howroyd Simon , Kendall Kevin , Kendall Michaela
Published: October 2013

Unmanned Air Vehicles (UAVs) powered by microtubular SOFCs (mSOFCs) are described for comparison with polymer fuel cells (PEFCs). Using propane as fuel, 7mm diameter mSOFCs have been tested in a 2m wingspan aircraft with a total weight of 6kg. The start-up time was 12 minutes to deliver 250W in a fuel cell/battery hybrid drive system. Tubes were YSZ cermet anode supported, with 10 µm YSZ electrolyte, 6µm SDC interlayer coated with 50µm LSCF cathode. Silver wires were used as interconnects. Pure propane fuel gas was mixed with air in a CPOX reactor using catalytic fuel processing mesh. A polymeric fuel inlet manifold gave cold sealing at the tube inlet ends which projected out of the hot box. Cathode air was provided in counterflow, preheated over an anode off-gas catalyst. The fuel utilization was 55%, output power of 250W. The fuel cell was incorporated in a hybrid electrical system with lithium polymer battery and inserted in a Skywalker X8 UAV with 500g of propane in an aluminum tank.
Low-Cost, REDOX-Stable, Low-Temperature SOFC Developed by Ceres Power for Multiple Applications: Latest Development Update
Authors: Leah Robert , Bone Adam , Lankin Mike , Selcuk Ahmet , Pierce Robin , Rees Lee , Corcoran Derek , Muhl Patrick , Dehaney-Steven Zac , Brackenbury Colin , Selby Mark , Mukerjee Subhasish
Published: October 2013

Ceres Power has developed a unique low temperature (500-620°C), low-cost metal-supported SOFC technology based on the use of thick-film Cerium Gadolinium Oxide (CGO) as the predominant oxygen ion conductor and structural ceramic, the fundamental details of which have been published previously (1). Since that paper was published, considerable progress has been made on developing the performance of the technology towards true commercial viability, particularly robustness to real-world REDOX and thermal cycling conditions, electrical efficiency and steady-state durability. These improvements have been achieved whilst maintaining the advantages of a low-temperature metal-supported design, particularly low material and balance-of-plant cost and inherent mechanical robustness. This has been demonstrated at both short-stack and 1 kW-class stack level. This paper provides a general overview of the status of Ceres SOFC technology and its applications.
Performance of Tubular Direct Carbon Fuel Cell Based on an Anode Support Solid Oxide Fuel Cell
Authors: Lim Tak-Hyoung , Lee Jong-Won , Lee Seung-Bok , Park Seok-Joo , Song Rak-Hyun
Published: October 2013

A tubular direct carbon fuel cell based on an anode support solid oxide fuel cell was fabricated and studied. Carbon black and molten carbonate were filled in the inner part of the tubular DCFC cell. The performance of the tubular DCFC cell at 800 oC had a maximum power density of 97 mW/cm2; this result indicates that the fabricated tubular DCFC is a promising candidate for many other practical applications, such as residential power generation (RPG) and auxiliary power unit (APU) systems.
Fabrication of Laminate-Type SOFC; Printed Fuel Cell
Authors: Suda Seiichi , Wiff Juan Paulo , Shimada Shu
Published: October 2013

We have developed a novel laminate-type SOFC stacks that are composed of thin each layers of electrolyte, electrodes and separator since 2005. These layers are prepared by tape casting and screen printing methods and these stacks are monolithically fabricated by simultaneous sintering these layers. We designate these novel stacks or systems as “Printed Fuel Cell”. We successfully fabricated 5-cell stacks that had 1.0-1.5 mm in thick. The stack showed reasonable OCV of more than 5 V at 750-800oC. Power density of the stack was previously lower than expected, but an adequate porosity and gas channel design of cathode much improved the performance.
Evaluation of Elastic and Strength Properties of Ni-YSZ Cermets for Solid Oxide Fuel Cells Under Redox Cycling
Authors: Sato K. , Miyasaka T. , Watanabe S. , Hashida Toshiyuki
Published: October 2013

The effects of pore volume in Ni-YSZ cermets on their mechanical properties under redox cycling were examined using a small punch (SP) testing method. The volume fractions of pores Vp in as-sintered NiO-YSZ specimens were in the range of 0-30%, and with the Ni/YSZ mixture ratio of 50:50%. All the measurements were conducted at 800 C. For Vp>20%, the measured Young’s modulus and strength of re-oxidized NiO-YSZ cermets were almost close to those of the as-sintered cermets. The experimental result indicates that the appropriate selection of Vp is necessary for ensuring the mechanical properties during redox cycling.
Redox Anode Supported Cell Performances Tested with Different Cathode Materials
Authors: Di Domenicantonio Giulia , Briois Pascal , Billard Alain , Ihringer Raphaël
Published: October 2013

Anode supported thin film electrolytes are nowadays the mostly used cells in the SOFC area. Unfortunately they are dramatically damaged if re-oxidation occurs in the anode chamber. In order to overcome this problem, Fiaxell Sàrl developed an anode supported half-cell, the 2R-Cell™, that provides robustness and reliability upon multiple thermo- and redox-cycles. Here we report on the performances and stability of 2R-Cell™ tested with different cathode materials: LSM, LSC in-situ and LSC-GDC. All presented measurements have been performed in the test rig developed by Fiaxell Sàrl and described in the following.
Metal-Supported Solid Oxide Fuel Cells with Impregnated Electrodes
Authors: Zhou Yucun , Zhan Zhongliang , Wang Shaorong
Published: October 2013

Metal-supported solid oxide fuel cells (SOFCs) containing porous 430L support, YSZ electrolyte and porous YSZ layers are fabricated by tape casting and co-firing. Nano Ni-Ce0.8Sm0.2O2-
δ(SDC) and La0.6Sr0.4Fe0.9Sc0.1O3-
δ(LSFSc) coatings, which act as anode and cathode catalysts, individually, are impregnated onto the internal surfaces of porous 430L and YSZ, respectively. Promising cathode polarization resistances ranging from 0.024 Ωcm2 at 800ºC to 0.155 Ωcm2 at 650ºC are obtained. The maximum power densities of the single cell are 0.68, 0.92, 1.09 and 1.23 Wcm−2 at 650, 700, 750 and 800ºC, respectively.
Low-Temperature Synthesis, Structural and Transport Properties of Doped LAMOX – Electrolytes for IT SOFS
Authors: Pavlova Svetlana , Kharlamova Tamara , Bespalko Yulia , Krieger Tamara , Sadykov Vladislav , Chesalov Yurii , Ulihin Artem , Uvarov Nikolai , Smirnova Alevtina
Published: October 2013

Doped La2-xRxMo2-yWyO9 (R= Bi, Gd, Pr, Sm, Nd; x=0-0.5, y=0.5-1) were synthesized via polymerized precursors method or high power mechanical milling (MM). The study of doped LAMOX genesis and structural properties using thermal analysis, XRD, SEM, IR and Raman spectroscopy has revealed that for all cations but Bi substituting La-position, the pure cubic β-phase is formed from polymerized precursors after calcination at 700°C. W-doped LAMOX have been obtained via low temperature calcination of MM products depending on W concentration. Due to a high dispersion of powders, high density pellets of doped LAMOX ceramics have been already obtained after annealing at 950°C. Their electrical conductivity measured by impedance spectroscopy depends on the doping cation nature being sufficiently high (up to 5.6∙10-3 S/cm at 630 ºC) at temperature below 650°C.
Evaluation of Stress Condition of Operated Anode Supported-Type SOFC under Operating Conditions Based on Raman Scattering Spectroscopy
Authors: Onuki S. , Onodera S. , Iguchi Fumitada , Shimizu M. , Kawada Tatsuya , Yugami Hiroo
Published: October 2013

Stress in an anode-supported type solid oxide fuel cell (SOFC) was measured by in-situ measurement using micro Raman scattering spectroscopy. The stress conditions evaluation method focuses on Raman spectra of samarium-doped ceria (SDC) which was used as an interlayer in SOFC. The shift of ceria Raman peak and peak width in SDC interlayer were measured to evaluate stress, temperature, and Sm concentration. We performed this method in the purchased cells of conventional anode-supported type SOFC under thermal cycles, which simulate start-up and shout down. Observed results suggested that not only thermal stress relaxation but also diffusion of samarium from an interlayer to an electrolyte, and stress relaxation by plastically deformation were occurred.
Sol-Gel Thin-Film Electrolyte Anode-Supported SOFC – From Layer Development To Stack Testing
Authors: Menzler Norbert H. , Han Feng , Sebold Doris , Fang Qingping , Blum Ludger , Buchkremer Hans Peter
Published: October 2013

One of the current R&D projects on solid oxide fuel cells concerns the reduction of the operation temperature. Nowadays stacks with anode-supported cells and an LSCF-cathode operate typically at a mean temperature of 700°C. The minimum temperature for SOFC using natural gas is approx. 650°C due to reforming limitations. Reducing temperatures below 600°C leads to lower costs, shorter start-up time and thus in-time power delivery by the system (e.g. for auxiliary power units). Forschungszentrum Jülich is also working on the development of an SOFC operating at 400°C for special applications, which can be fueled either with hydrogen (produced by, for example, electrolysis using renewable energy) or with reformate gas based on, for instance, ethanol/methanol. The main challenge for using the SOFC at such low temperatures is, besides electrode activities, overcoming the resistances, especially the ohmic resistance of the electrolyte. This can be achieved in two ways: by introducing materials which show higher oxygen diffusivity or by using the classical materials and minimizing the electrolyte thickness down to values below 2µm.
Performance of Ultra-Thin Film Solid Oxide Fuel Cells in Methane and Natural Gas Fuels: The Role of Electrode Microstructure
Authors: Takagi Yuto , Kerman Kian , Ramanathan Shriram
Published: October 2013

This proceedings manuscript describes representative results of thin film micro-solid oxide fuel cells (micro-SOFCs) utilizing nano-porous ruthenium (Ru) and Ru – gadolinia doped ceria (CGO) nano-composite anodes, investigated for operation with various fuels. 8 mol% yttria-stabilized zirconia (8YSZ) and compositionally graded CGO-8YSZ thin films were fabricated on silicon substrates as self-supported electrolytes. Performance of devices integrating such electrodes and electrolytes are presented with methane and natural gas as fuels. Oscillations in fuel cell current were observed when nano-porous Ru and Ru-CGO anode micro-SOFCs were operated at constant voltage with methane. Degradation mechanisms of pure metallic electrodes are then compared to composite electrodes at the intermediate temperature range of 300 - 500 °C. New synthesis methods to realize percolating ultra-thin composite electrodes is highlighted as a promising research direction.
Rare Earth Co-Doped Nanocrystalline Ceria Electrolytes for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFC)
Authors: Babu Anantharaman Surendra , Bauri Ranjit
Published: October 2013

Samaria doped ceria (SDC) co-doped with Nd2O3 (Nd-SDC) and doubly co-doped with Nd2O3 and Pr2O3 (Pr-Nd-SDC) was prepared by solution combustion synthesis. X-ray diffraction studies confirmed the nanocrystalline nature of the powder with cubic fluorite phase. Raman spectroscopy showed the characteristic cubic fluorite peak (464 cm-1) of ceria and the vacancy concentration calculated from the peak area ratio (A550/A464) was found to be higher in Pr-Nd-SDC (0.556) compared to Nd-SDC (0.168). The powder was compacted into discs and sintered to obtain dense pellets. The sintering temperature was found to be considerably lower than that required for microcrystalline SDC. The electrical conductivity was obtained by impedance spectroscopy. The doubly co-doped sample (Pr-Nd-SDC) exhibited higher conductivity and lower activation energy compared to the co-doped sample (Nd-SDC).
Solid Oxide Fuel Cells Using Lanthanum Silicate Electrolyte Films
Authors: Mieda Hiroyuki , Mineshige Atsushi , Nishimoto Takuma , Tange Mika , Daiko Yusuke , Yazawa Tetsuo , Yoshioka Hideki , Mori Ryohei
Published: October 2013

Anode supported solid oxide fuel cells (SOFCs) utilizing apatite-type Mg-doped lanthanum silicate (MDLS) electrolytes obtained from nano-sized printable paste coated on NiO-MDLS substrates were fabricated. With optimizing fabrication conditions of MDLS films, anode and cathode materials, the performance was largely improved, and the high performance SOFC based on apatite-type electrolyte was successfully developed for the first time.
Protective Yttrium Doped Barium Zirconate Layer on Yttrium Doped Barium Cerate Proton Conductive Membrane
Authors: Maide Martin , Korjus Ove , Vestli Mihkel , Lust Enn , Nurk Gunnar
Published: October 2013

This paper describes the developments of the project about the synthesis of proton conductive BaCe0.9Y0.1O3-δ
(BCYO) membrane with thin chemically more stable protective BaZr0,9Y0,1O3-
δ (BZYO) layer. Dense pellets of BCYO with good phase purity were synthesized from nanopowders and electrochemical as well as microstructural parameters were characterized. The influence of BCYO membrane microstructure on conductivity and activation energy was studied and best membrane material has been selected. Deposition of protective BZYO layer was performed using 120 kHz ultrasound spray nozzle. Influence of substrate temperature, raw salt concentration, concentration of solvents on the layer characteristics and the thermal treatment program parameters were studied and optimized. Crack-free raw films were prepared. More detailed optimization of thermal treatment program for deposit of the protective layer is in progress and first results are available.
Inkjet Printing of Direct Carbon Solid Oxide Fuel Cell Components
Authors: Tomov R I , Dudek M , Hopkins S C , Krauz M , Wang H , Wang C , Shi Yixiang , Tomczyk P , Glowacki B A
Published: October 2013

The feasibility of inkjet printing of electrodes for DC-SOFC was tested. A variety of materials was deposited by direct ceramic inkjet printing (DCIJP). The technology allows for easy modification of the coatings, including thickness control, porosity graduation and precise infiltration with catalytically active materials. The comparative tests showed a similar performance for screen printed and inkjet printed cells (peak power density of ca. 80 mW cm-2 at 780°C). In addition DCIJP offers minimization of the usage of expensive precursor materials. It was also found that infiltration of the anode by inkjet printing of sol inks (CuNiO3) can lead to an improvement in DC-SOFC performance.
Non-Stoichiometry in Oxide Thin Films Operating Under Anodic Conditions: A Chemical Capacitance Study of the Praseodymium-Cerium Oxide System
Authors: Chen Di , Bishop Sean R. , Tuller Harry L.
Published: October 2013

PrxCe1-xO2-δ can potentially serve as both cathode and anode in solid oxide fuel cells given that it exhibits significant mixed ionic-electronic conductivity (MIEC) under both cathodic and anodic conditions. While MIEC depends strongly on oxygen nonstoichiometry δ, there have been few ways to extract this information reliably and in situ, particularly for thin films. In this work, this is achieved by analysis of chemical capacitance values extracted from impedance spectroscopy data obtained on electrochemical cells of the form Pr0.1Ce0.9O2−δ/ Y0.16Zr0.84O1.92 / Pr0.1Ce0.9O2−δ operating at temperatures between 500 to 700 oC and over the pO2 range of 10-31-10-16 atm. The enthalpy of reduction for the Pr0.1Ce0.9O2−δ thin film is derived.
Effect of Ceria Addition in SOFC Anodes on Sulfur Poisoning
Authors: Sugimoto Junki , Kawabata Tsutomu , Shiratori Yusuke , Taniguchi Shunsuke , Sasaki Kazunari
Published: October 2013

In SOFCs, a wide range of fuel gases can be applied, but fuel impurity tolerance may be desired. By applying gadolinia-doped ceria (GDC) anode material, we analyzed power generation characteristics and internal reforming followed by high-resolution electron microscopy in order to moderate sulfur poisoning. Effect of ceria addition into the anodes layers on sulfur poisoning is systematically analyzed and discussed.
Microstructure Observation of Ni/YSZ Boundary by TEM and STEM
Authors: Liu Shu-Sheng , Toh Shoichi , Daio Takeshi , Koyama Michihisa , Matsumura Syo
Published: October 2013

Solid oxide fuel cell attracts much attention due to its advantages such as high efficiency and low carbon emission. For a typical Ni/YSZ anode, it is essential to understand the relationship between performance and microstructure of Ni/YSZ interface and Ni/YSZ/pore triple-phase boundary. Herein, the crystallographic orientation relationship between Ni and YSZ in a practical cell was investigated by transmission electron microscopy (TEM), and scanning TEM (STEM). The TEM specimen was lifted out from bulk cell in a focused ion beam-scanning electron microscopy. It was found that the orientation relationship is much more complicated than that of a specially designed Ni/YSZ sample.
Moleular Dynamics Study for Sintering Property Analysis of Ni-YSZ Cermet
Authors: Nakao Kazuhide , Kohno Haruhiko , Ishimoto Takayoshi , Koyama Michihisa
Published: October 2013

Microstructural change of porous electrodes in SOFC caused by sintering affected by materials and impurities is one of the main factors of the long-term degradation. Since it is difficult to clarify the effects of materials and impurities on sintering by experiments, atomistic scale simulation is important. In this study, we performed molecular dynamics (MD) simulation of porous structure of Ni and analyzed sintering properties of porous structure by employing master sintering curve theory. We have succeeded to obtain the sintering activation energy and its size dependency and to identify the dominant sintering mechanism by comparing sintering activation energy with activation energy of surface diffusion on each facet.
Electroless Deposited Cu on the Ni/YSZ Anode for the Direct CH4-SOFC
Authors: Rismanchian Azadeh , Chuang Steven S. C.
Published: October 2013

The effect of reducing time on Cu-Ni alloy formation in a Cu electroless plated Ni/YSZ anode-supported solid oxide fuel cell was investigated. Reduction of the Cu-Ni/YSZ cell in H2 allowed the diffusion of the Cu into the Ni and the formation of Cu-Ni alloy, as evidenced by XRF elemental analysis and characteristic diffraction peaks in XRD. The formation of Cu-Ni alloy is required to inhibit carbon formation on the surface of anode. The Cu-Ni anode prepared by electroless plating followed by 30 h reduction in H2 exhibited significant resistance to coking at 750oC with a CH4 /He feed compared to anode prepared by 1 h reduction in H2.
Nanostructured Ni/YSZ Anodes: Fabrication and Performance Analysis
Authors: Szász Julian , Klotz Dino , Störmer Heike , Gerthsen Dagmar , Ivers-Tiffée Ellen
Published: October 2013

The design state of the art SOFC anodes limit the electrooxidation reaction inherently by its µm-scaled microstructure. An increase in cell performance of anode supported SOFCs (ASC) is achieved by a method, which induces the formation of an additional nanostructured Ni/YSZ layer in the electrochemically active region of the anode. This in-operando technique is based on a short-time application of a high current in reverse direction (reverse current treatment - RCT). In this contribution we investigate the nanostructured layer in a new model anode setup on a single crystalline YSZ substrate. This new setup guarantees homogenous experimental conditions due to simplified cell geometry. It is possible to control the RCT parameters and fabricate nanostructured layer with thicknesses up to 1100 nm and grain sizes between 10…20 nm. After conducting the RCT, a dense ~200 nm thin Ni film is still remaining, covering the whole nanostructured layer. Gas impermeability of the Ni film inhibits at first sufficient fuel gas access to the electrochemically active region in the nanostructured layer. Open porosity in the dense Ni film is thus necessary to characterize the electrochemical performance of the nanostructured model anode by means of impedance spectroscopy. Therefore an oxidation-reduction cycle is introduced leading to an impressively low anode polarization resistance compared to technical SOFC anodes. Furthermore, TEM analysis provides new information of the serve interaction of YSZ with the adjacent Ni phase during RCT, which is essential for a controlling and optimizing the fabrication process.
Doped Samarium Ferrite Perovskites as Carbon and Sulfur Resistant Anodes for Low Temperature Solid Oxide Fuel Cells
Authors: Bukhari Syed M. , Penwell William D. , Giorgi Javier B.
Published: October 2013

Perovskite type oxides (ABO3) have opened a new door to solve operational issues of SOFC anodes. One of the great advantages of these materials is that their properties can be easily tailored according to the desired applications, by introducing substitutions at A and B- sites. Doping Ce, Co and Ni in SmFeO3 solves not only the reduction instability issue of these perovskites, but also makes these materials suitable as anodes. The resistance to coke formation is shown for three prime candidates of this perovskite family (Sm0.95Ce0.05FeO3-δ, Sm0.95Ce0.05Fe0.97Co0.03O3-δ, and Sm0.95Ce0.05Fe0.97Ni0.03O3-δ). These anodes show stable performance in pure methane fuel in the temperature range of 450 to 650°C. In addition, performance of these anodes in the presence of 5% H2S is higher than for pure H2.
Preliminary Studies about Synthesis and Electrical Properties of Ruthenium Doped Lanthanum Strontium Titanate as a Potential Anode of Solid Oxide Fuel Cells
Authors: Yoon Heechul , Zou Jing , Park Sungtae , Sammes Nigel Mark , Chung Jong Shik
Published: October 2013

The lanthanum strontium titanate (LST) is one of the most representative alternative anode materials. Although it shows low catalytic properties, the disadvatage could be improved by doping of ruthenium which is widely used as catalyst under steam reforming reaction or oxidation reaction. The ruthenium doped lanthanum strontium titanates (LSTRs) powders were synthesized by complex EDTA-citrate method showing well crystallinity. Additionally, the prepared samples were evaluated through various experimental tests. For example, the stability in the reducing atmosphere and chemical compativity with YSZ electrolyte such as reactivity test in high temperature were confirmed by XRD (X-ray diffraction). And electrical conductivity in wet H2 atmosphere at 900ºC is about 350.6 S/cm, 342.4 S/cm and 179.1 S/cm with sintered bar of LST, LSTR0.02 and LSTR0.05, respectively.
Oxygen Electrode Kinetics and Surface Composition of Dense (La0.75Sr0.25)0.95MnO3 on YSZ
Authors: Wu Yuehua , Hansen Karin Vels , Norrman Kion , Jacobsen Torben , Mogensen Mogens
Published: October 2013

Lanthanum strontium manganate (LSM) micro-electrodes with the nominal composition of (La0.75Sr0.25)0.95MnO3 were deposited on yttria stabilized zirconia (YSZ). The diameter varied from 20 – 100 μm and the thickness was kept constant at ca. 0.5 μm. Electrochemical characterization was carried out in situ at temperatures from 660 to 860 °C using controlled atmosphere high temperature scanning probe microscope (CAHT-SPM) set-up for measurements of impedance spectroscopy and potential sweep. The oxygen partial pressure, pO2, was varied. Further, ex situ surface analysis by time of flight secondary mass spectrometry (TOF-SIMS) and structure examination by scanning electron microscopy (SEM) were performed. Segregation of Sr and La oxides to LSM surfaces and Mn rich oxide to the three phase boundary (TPB) was observed. YSZ and LSM attract different oxides/impurities. The oxygen electrode kinetics are discussed in light of the surface compositions and compared with the literature on microelectrode and composite LSM-YSZ electrode kinetics.
Equivalent Circuit Model Analysis of LSM/ScSZ Composite Cathodes Prepared by Impregnating LSM/ScSZ Powder Slurry into a Prefabricated Porous ScSZ Layer
Authors: Shimada Hiroyuki , Hagiwara Akifusa , Ihara Manabu
Published: October 2013

Relationship between microstructure and performance of Sr-doped LaMnO3 (LSM)/Sc2O3-stabilized ZrO2 (ScSZ) composite cathodes was investigated using equivalent circuit models (ECMs) analysis. The cathodes were prepared by impregnating prefabricated porous ScSZ layers with a LSM/ScSZ powder slurry. This method enabled control of the electrolyte surface roughness. Three different ECMs were used for analysis: (i) commonly used ECM in which resistances were connected in series; (ii) ECM consisting of the double-phase boundary (DPB) and the triple-phase boundary (TPB) at the LSM/ScSZ interface; and (iii) ECM representing a three-dimensional electrode. The analysis revealed that impedance response is influenced by the area ratio of the DPB to the TPB although cathode performance is mainly determined by the TPB.
The Application of Ion Beam Analysis to Mass Transport Studies in Mixed Electronic Ionic Conducting Electrodes
Authors: Kilner John A. , Tellez Lozano Helena , Burriel Monica , Cook Stuart , Druce John
Published: October 2013

The measurement of the mass transport and oxygen exchange in materials for SOFCs has been greatly aided by the use of ion beam analysis techniques. In particular this has focused on the use of Secondary Ion Mass Spectrometry (SIMS) to measure diffusion profiles of oxygen 18 in ceramics to determine the kinetics of the bulk transport of oxygen. A second ion beam technique, Low Energy Ion Scattering (LEIS) can provide important information about the composition of the outermost atomic layers of the same materials where the gas/solid oxygen exchange process is taking place. The application of the newer technique of LEIS to materials for air electrodes is discussed and the behaviour of some common perovskite materials is explored.
Electronic Activation at Oxide Hetero-Structure at Elevated Temperatures – Source of Markedly Accelerated Oxygen Reduction Kinetics
Authors: Chen Yan , Cai Zhuhua , Kuru Yener , Tuller Harry L. , Yildiz Bilge
Published: October 2013

To understand ultra-fast oxygen reduction reaction kinetics near La0.8Sr0.2CoO3/(La0.5Sr0.5)2CoO4 (LSC113/
214) interface, a combination of in-situ scanning tunneling spectroscopy and focused ion beam milling was used to study the local electronic structure near LSC113/
214 interface at elevated temperature and in oxygen. The electronic activation of LSC214 by the coupling with LSC113, concurrent with the fast oxygen incorporation on LSC214, was identified to be a key reason. These results put forward the electronically coupled oxide structures as novel cathodes. We generalize and further test this idea on a La0.8Sr0.2CoO3/La2NiO4 system, which shows a similar electronic activation of La2NiO4 at elevated temperatures.
Influence of Thin Films Structure of Gd0.5Sr0.5CoO3 Cathode on Impedance Spectroscopy
Authors: Mukai Takehito , Tsukui Shigeki , Yoshida Kenichi , Adachi Motoaki , Goretta Kenneth C
Published: October 2013

Thin films of the perovskite Gd0.5Sr0.5CoO3 (GSCO), a cathode material, were fabricated by pulsed laser deposition methods. Two kinds of single-crystal (100) 8-mol% Y2O3 doped zirconia (YSZ) were used as substrate: with one surface polished and with both surfaces polished. GSCO thin films deposited on YSZ substrates with a polished surface had a columnar polycrystalline structure. The surface structure of the GSCO thin film was strongly affected by the substrate surface structure. The GSCO films on the unpolished YSZ were much rougher. From impedance measurements, because of the large surface contact area, the symmetrical cell with GSCO thin film deposited on YSZ with only polished one surface exhibited at a temperature of 400°C small resistances that were five times lower than the resistances of the cell which contained a GSCO thin film deposited on YSZ with both surfaces polished.
The Effect of Cation Substitution on Chemical Stability of Ba0.5Sr0.5Co0.8Fe0.2O3-δ
-Based Mixed Conductors
Authors: Wang Fang , Nakamura Takashi , Yashiro Keiji , Mizusaki Junichiro , Amezawa Koji
Published: October 2013

Cubic perovskite Ba0.5Sr0.5Co0.
8Fe0.1R0.1O3–δ
(R=Fe, Nb, Mo, Sb) was synthesized, and the chemical stability under high oxygen partial pressure (p(O2)) was studied by using HT-XRD in the temperature range of 773-1373 K. It was found that Ba0.5Sr0.5Co0.
8Fe0.1Sb0.1O3–δ
was remarkably stable than Ba0.5Sr0.5Co0.
8Fe0.2O3–δ
and Ba0.5Sr0.5Co0.
8Fe0.1Mo0.1O3–δ
in high p(O2) condition. The effect of B-site substitution on the CO2-tolerance of Ba0.5Sr0.5Co0.
8Fe0.1R0.1O3–δ
was also investigated by TG-DTA analysis at 300-1373 K. It was demonstrated that the chemical stability of Ba0.5Sr0.5Co0.
8Fe0.2O3–δ
against CO2 could be signiﬁcantly improved when Fe were partially substituted by Nb or Sb ions.
Structural, Thermal and Electrical Study of Ca2+, Sr2+ Substituted BiFeO3 for IT-SOFC
Authors: Thakur Samita , Pandey O. P. , Singh K.
Published: October 2013

Bi0.5A0.5FeO3 (A=Sr2+, Ca2+) has been synthesized by solid state reaction method to investigate the effect of two different cations on structural, thermal and electrical properties of BiFeO3. The samples were characterized by X-ray diffraction, thermogravimetry (TG), dilatometery, and impedance spectroscopy. All samples are mono-phasic and exhibit cubic symmetry (pm-3m) as confirmed by Rietveld refinement. Bi0.5Ca0.5FeO3 shows higher conductivity (~ 1.71×10-2 S/cm) as compared to Bi0.5Sr0.5FeO3 (~ 6.74×10-3 S/cm). TG results indicate that Bi0.5Ca0.5FeO3 is thermally more stable as compared to Sr2+ doped system. Sr2+doped BiFeO3 shows higher thermal expansion coefficient as compared to Ca2+ doped system
Oxidation Behavior of Fe-Cr Ferritic Alloy for SOFC Interconnects ZMG232G10 in Air and H2/H2O
Authors: Yamamura Kazuhiro , Uehara Toshihiro , Tanaka Shigenori , Yasuda Nobutaka
Published: October 2013

ZMGTM232G10 is an improved Fe-Cr ferritic alloy for SOFC interconnects which has better oxidation resistance than ZMG232L. Oxidation behavior of ZMG232G10 was investigated in air as well as H2/H2O atmosphere at 850 oC. ZMG232G10 showed almost same oxidation weight gain in both atmospheres. Oxidation behavior of some commercial Fe-Cr ferritic stainless steels was also investigated. 430 type stainless steel indicated a large amount of oxidation weight gain in air although it indicated a small amount of oxidation weight gain in H2/H2O. Oxide layers formed on the surface of ZMG232G10 were different from those of commercial stainless steels.
Effect of Thermal-Sprayed Mn1.5Co1.5O4 Coating on Oxidation Suppression of Metallic Interconnects
Authors: Fung Kuan-Zong , Tsai Shu-Yi , Ho Hsin-Chia
Published: October 2013

Metallic interconnects are less expensive, more conductive and able to form complex shapes than ceramic interconnects for SOFC applications. Most metallic interconnects use alloys containing chromium. At elevated temperatures, chromia scales react with cathode and degrade its performance. Manganese cobalt oxide ((Mn,Co)3O4 , (MCO), with spinel structure is found to be a good material to form a protective coating for metallic interconnects. In this study, the high-temperature ferritic stainless steel Crofer 22H and nickel-chromium alloy Inconel 625 were thermally sprayed with MCO, and the oxidation, scale structure, and resistance of metallic substrates were investigated using XRD, TEM and SEM.
Influence of Chromium Evaporation and Oxidation on Interconnect Steels at 650-850°C
Authors: Falk Windisch Hannes , Froitzheim Jan , Svensson Jan-Erik
Published: October 2013

Chromium evaporation and oxide scale growth are two important degradation mechanisms in SOFCs when chromia-forming alloys are used as the interconnect material. In this paper the influence of temperature on both mechanisms were studied. Isothermal exposures were carried out for 24, 168 and 500h at 650, 750 and 850°C in an air-3%H2O atmosphere. In the second part uncoated and metallic nano-coated samples were exposed for 3000h. This study clearly points out the relevance of Cr-evaporation at reduced temperatures and the importance of high quality coatings not only to protect the cell from cathode poisoning but also to reduce the risk of Cr-depletion within the interconnect steel.
Kinetics of Stainless Steel 441 Initial Oxidation at 600~950oC in Different Oxygen Pressures
Authors: Chen Zhi-Yuan , Wang Li-Jun , Li Fu-Shen , Chou Kuo-Chih , Li Li-Fen , Sun Zaihong
Published: October 2013

The reduced operating temperatures of SOFCs makes the possible of using metallic alloys as interconnect. Stainless steel 441 is one of the common studied materials for the interconnect component. The oxidation behavior of a stainless steel 441 in various oxygen pressure atmospheres in the initial 2 hours was investigated gravimetically in the temperature range of 600 ~ 950oC in the present work. And the morphology of the scale surface of oxidized alloy was observed by SEM, and the impacts of oxygen pressure and temperature on the oxidation were examined. The oxidation mechanisms were analyzed by Real Physical Picture model. Different oxidation kinetic processes were found in various exposure temperatures and oxygen pressures. In the case of 900~950 oC in pure oxygen, it obeyed two stages linear rate law. When the temperature was reduced to 600~800 oC in pure oxygen, the oxidation of 441 alloy followed linear-to-parabolic rate law. But only linear rate law was obeyed in the lower oxygen pressure atmospheres at 800 and 900 oC in the initial 2 hours. The kinetic parameters of the alloy oxidation process were given.
Degradation of Ferritic Steel Interconnects in SOEC Environments
Authors: Alnegren Patrik , Froitzheim Jan , Svensson Jan-Erik
Published: October 2013

This study investigates the corrosion performance of selected ferritic steels in simulated solid oxide electrolysis cell (SOEC) environments for exposure times up 500 h. Ferritic steels have many properties that are desirable for interconnects but suffer from oxidation and chromium evaporation over time. Four different FeCr alloys have been exposed in different concentrations of dry O2 (anode side) and in 34% H2O -3% H2-Ar (cathode side) at 850°C and gravimetrical measurements have been performed to study oxidation rates. Chromium evaporation has been measured and compared for the oxygen containing environments. Chromium evaporation was found to vary largely with oxygen partial pressure, while the oxidation rate of the steels did not vary substantially in the different oxygen partial pressures. Differences in oxidation behavior of the steels were observed between the exposures in dry O2 and in 34% H2O -3% H2 -Ar. Both reduced and increased oxidation rates were observed in the cathode side atmosphere compared to the oxygen side atmosphere for different materials.
Mechanochemical Synthesis of Manganese Cobalt Spinel as Interconnector Protective Coating Material First Experimental Findings
Authors: Bellusci Mariangela , McPhail Stephen J. , Modena Stefano , Montinaro Dario , Padella Franco , Puleo Fabrizio , Reale Priscilla
Published: October 2013

In the frame of an activity oriented on the development and characterization of cells and stacks for the integration in a micro-CHP system, synthesis, formulation and optimization of manganese cobalt spinel for the deposition of protective coatings on interconnector plates have been performed. A description of the process is given. Characterization of spray coated interconnector samples and discussion of the experimental findings are reported.
Identification of Second Phases for Sr1-XLaxTiO3 Perovskites Synthesized by Citric-Gel Method
Authors: Fujikawa Masaki , Higashi Yuta , Nomura Yutaro , Ueki Tomoyuki , Sugano Satoshi , Murai Kei-ichiro , Moriga Toshihiro , Mori Masashi
Published: October 2013

We prepared the Sr1-xLaxTiO3 perovskites (0≤x≤1.0) synthesized by the citric-gel method using TAS-FINE ((NH4)4[Ti2(C6H4O7)2(O2)2]) as a Ti source and examined second phases formed in the perovskite matrix. It was found that the second phase seen in the compositional region of 0.2≤x≤0.4 when fired at 1100-1500ºC was confirmed to be Sr-doped La2O3 with the rare-earth B-type structure, which should be the same impurity phase as appeared in the La-doped SrTiO3 during SOFC operations at around 900ºC.
Copper Based Conversion Coatings on Ferritic Stainless Strip Steel as Solid Oxide Fuel Cell Interconnects: Oxidation Performance and Chromium Evaporation
Authors: Grolig Jan Gustav , Abdesselam Hayat , Gas Maxime , Windisch Hannes Falk , Froitzheim Jan , Svensson Jan-Erik
Published: October 2013

Ferritic stainless steels such as Crofer 22 H or Sanergy HT have been proven to be effective interconnect materials when additionally coated. These coatings, mainly based on cobalt spinels, successfully prevent chromium evaporation and are stable for long exposure times. A new approach is using copper based spinel coatings which are promising concerning price, conductivity and stability. This investigation is dedicated to a selection of copper spinel conversion coatings, their stability and ability to prevent chromium evaporation. Chromium release was monitored in humidified air (at 850 °C) using the denuder technique. The coatings were post analysed utilizing electron microscopy.
Long Term Behavior of Viscous High-Temperature Sealing Glasses
Authors: Suffner Jens , Dobler Carina
Published: October 2013

Crystallizing glasses are considered the state-of-the art solution to obtain a hermetic seal for solid oxide fuel cells. While these glass-ceramics exhibit good bonding to the interconnect alloys of the stack as well as good mechanical strength, viscous flow at operation temperatures may be expected only to a minor extend due to their large crystalline content. For the ability of the glasses to self-heal at elevated temperatures, a low degree of crystallinity is required. For that reason, alkaline-free viscous high-temperature sealing glasses for the application between 700 and 800 °C were developed at Schott and long term stability was studied for > 1 000 h.