bluuebunny/crossref_metadata_2025 huggingface dataset:
Solid Oxide Fuel Cell Development at NIMTE
Authors: Wang Wei Guo , Guan Wanbing , Li Huamin , Wang Zhenwei , Wang Jian Xin , Wu Yanan , Zhou Shenghu , Zuo Guokun
Published: September 2009

The biggest SOFC R&D activities in China are conducted at NIMTE where 45 full time staffs are vertically integrated. We manufacture and sale planar anode supported cells for international market with the highest performance/price ratio. We offer various nano-powders including LSM, LSCF, LSC, CGO, YSZ and SSZ. Long term tests on performance degradation, in particular at low temperature and high current density, are intensively carried out in our cell testing group. We demonstrated low cost stack by combining internal manifolding design and low cost components selection. A five cell short stack has run for more than 3000 hours and the voltage is monitored individually. Stacks of 500W to kW power range are built and tested. We successfully manufactured 30×30cm2 cells for multi-kilowatt single stack. 2kW power and heat co-generation system are under development and 20kW electrical generation system are planned this year in collaboration with a big Chinese electricity generation company.
Development of SOFC Stack at NGK Spark Plug Co., Ltd.
Authors: Nishijima Dai , Ishikawa Hiroya , Shibata Masahiro , Uematsu Hideki , Sumi Hiroshi , Okuyama Yasuo , Todo Yusuke , Komatsu Daisuke , Ishida Satoru , Furusaki Keizo
Published: September 2009

SOFC stack for residential SOFC system is improved due to cell optimization and reduction of size and weight of the stack. A power density of 1.6 W/cm2 is obtained at 0.7 V with button cell due to the cathode optimization. The cathode optimization is successfully applied to fabrication of a large cell that has an active electrode area of 100 cm2. An integrated power stack with 18 large cells shows an output power of 1.1 kW and DC power efficiency of 62 % (LHV) when the fuel utilization is 80 % in the measurement at 700 ºC with methane fuel.
Status Report of SOFC Development and Pilot Manufacturing at SOFCpower Srl
Authors: Bertoldi Massimo , Bucheli Olivier , Ravagni Alberto , Autissier Nordahl , Signorini Michele , Modena Stefano
Published: September 2009

SOFCpower-HTceramix' mission is to offer new energy solutions in the deregulated electricity market, based upon its highly efficient Solid Oxide Fuel Cell (SOFC) technology. SOFCpower develops SOFC stacks and thermally integrated stacks (HoTbox{trade mark, serif}) for OEM companies commercializing new power generators and co-generation systems. Since 2008, SOFCpower has implemented a cost-effective pilot production line for cells, stacks and HoTbox{trade mark, serif} power modules for residential co-generation with a capacity of 2 MW/y in Trento (IT). Furthermore, investments on testing facilities and infrastructures have been made in the same site in order to ensure quality of production and to certify stack durability. As a consequence, it was possible to speed-up cell and stack development and to progress in stack robustness and reproducibility of its performance, achieving electrical efficiency above 50% at stack level without internal reforming. The paper gives an up-date on the status of the manufacturing line and the test bench installation. Performance and stability data for SOFCpower stacks produced within the pilot manufacturing plant are presented, as well an up-date on progresses made on the development of large stacks (> 1 kW).
Development of SOFC Stacks at Ceramic Fuel Cells Limited
Authors: Love Jonathan , Amarasinghe Sudath , Selvey David , Zheng Xiao , Christiansen Lars
Published: September 2009

Ceramic Fuel Cells Limited (CFCL) has developed a highly efficient and stable solid oxide fuel cell stack for the micro-CHP and electrical generator markets operating on natural gas producing electricity to the grid at 1 - 2 kWe. Stack life of over one year with less than 0.5% per 1000 hours voltage degradation has been achieved. An electrical efficiency (LHV) of 68% is being achieved by the stack for gross DC electricity that enables CFCL's product to export AC electricity to the grid at 60% electrical efficiency. This paper describes CFCL's advances in cells and stacks that have enabled the achievement of these results.
3kW SOFC Power Generation Module Developed by NTT/THG/SPP
Authors: Arai Hajime , Hayashi Katsuya , Yoshida Yoshiteru , Yokoo Masayuki , Mizutani Yasunobu , Ukai Kenji , Katsurayama Koichi , Orishima Hiroshi , Hirakawa Makoto , Uwani Hiroyuki , Kashima Shoichi
Published: September 2009

Nippon Telegraph and Telephone (NTT), Toho Gas (THG) and Sumitomo Precision Products (SPP) are jointly developing solid oxide fuel cell (SOFC) systems as industrial stationary power generation systems. Two SOFC stacks composed of 40 anode-supported cells with LNF cathodes were integrated to form a 3 kW-class SOFC power generation module together with a steam generator, a steam reformer, a post combustor, heat exchangers and a start-up burner, surrounded by thermal insulators. This module provided long-term and maximum electrical conversion efficiencies (LHV) of 56 % and 59 %, respectively. A half load test and a stand-by test were also successfully conducted.
Status of Development and Manufacture of Solid Oxide Fuel Cell at Topsoe Fuel Cell A/S and Riso̸/DTU
Authors: Christiansen Niels , Hansen John Bo̸gild , Holm-Larsen Helge , Juel Jo̸rgensen Mette , Wandel Marie , Vang Hendriksen Peter , Hagen Anke , Ramousse Severine
Published: September 2009

Topsoe Fuel Cell (TOFC) provides the SOFC technology platform: Cells, stacks, and integrated stack module for different applications and collaborates with integrator partners to develop, test and demonstrate SOFC applications. The technology development is based on a R&D consortium with Riso̸ National Laboratory (Riso̸/DTU) which includes material synthesis and cost effective ceramic manufacturing methods for anode and metal supported flat planar cells in addition to multilayer assembling for compact stacks with metallic interconnects. The development is focussing on high electrochemical performance and durability as well as maximal robustness. In 2008 TOFC has constructed a 5 MW/year cell and stack production facility in Denmark featuring all the necessary unit operations from ceramic powder, continuous tape casting, screen printing, spray painting and sintering to complete stack modules. TOFC's engagement in SOFC technology includes system development in collaboration with system partners and development and manufacturing of integrated stack assemblies called PowerCore.
Development and Field Test Results of Residential SOFC CHP System
Authors: Suzuki Minoru , Iwata Shin , Higaki Katsuki , Inoue Shuich , Shigehisa Takashi , Miyachi Itaru , Nakabayashi Hidenori , Shimazu Kenji
Published: September 2009

At 2004, Osaka Gas Co., Ltd. and Kyocera Corporation launched joint development of residential SOFC CHP system. In order to fit Japanese urban market, we decided rated output of system as 700W and have reduced the size of a power generation. At rated power, ac 700W, net ac efficiency and hot water heat recovery efficiency is 45% (LHV) and 40% (LHV), respectively. From FY2007, we took part in the "Demonstrative Research on Solid Oxide Fuel Cells" hosted by the New Energy Foundation in 2007. Osaka Gas installed SOFC systems into 45 sites in FY2007 and FY2008. We demonstrated high energy saving effect for various houses and improved durability and reliability of system. Hereafter, new joint development, Osaka Gas, Toyota Motors, Kyocera and Aisin Seiki, aims early commercialization of residential SOFC CHP system.
Status of Hexis SOFC Stack Development and the Galileo 1000 N Micro-CHP System
Authors: Mai Andreas , Iwanschitz Boris , Weissen Ueli , Denzler Roland , Haberstock Dirk , Nerlich Volker , Sfeir Josef , Schuler Alexander
Published: September 2009

Hexis is developing the micro-CHP SOFC-system Galileo 1000 N. Field tests with the Galileo 1000 N were started and at present 17 systems are installed in the field. Additional 13 systems are installed at Hexis' labs. In a system test with improved cells, an electrical power output of more than 1000 W (AC, net), an electrical efficiency of more than 40% (DC) and 36% (AC, net) could be achieved, while another test showed a total efficiency of more than 90% (LHV). One of the lab systems runs now for more than 15000 h with a power degradation rate of 1.9% per 1000 h. A 5-cell stack with a similar setup is running for more than 15000 h with a voltage degradation of approx. 1% / 1000 h, while a more recent test showed less than 0.5% / 1000 h degradation for 9000 h. In the field, a system has been operated for more than 7200 h until now. It was shown that 5-cell stacks can tolerate more than 12 full redox-cycles.
Long-term Stability of Segmented Type Cell-stacks Developed for Residential use less than 1 kW
Authors: Matsuzaki Yoshio , Hatae T. , Yamashita Shouji
Published: September 2009

Long-term stability of segmented-in-series type cell-stack operable at intermediate temperature was investigated. Durability tests in an electric furnace were conducted under a standard condition as well as under controlled severe conditions in which a particular test parameter was set to severe value in order to define accelerating factors of deterioration. In order to estimate the degradation phenomenon in the real system, the durability tests were conducted also in the simulated system condition in the furnace with temperature distribution of 120 {degree sign}C and reformed methane as a fuel. Cell-tacks under the "standard" condition at a current density of 0.24A/cm2 and temperature of 775 {degree sign}C showed stable performance for experimental period up to 4000hrs. The degradation rates of the cell-stacks were found to be 0.27-1.04%/1000h with an average degradation rate of 0.6 %/1000h. Two accelerating factor of deterioration have been found through durability tests under controlled severe conditions. Then the cell-stacks were modified successfully to improve the durability with lower degradation rates.
Power Dense SOFC Stacks for Mobile Applications
Authors: Erikstrup Niels , Jensen Marie D. , Nielsen Martin R. , Clausen Thomas N. , Larsen Peter K.
Published: September 2009

Topsoe Fuel Cell A/S has developed a SOFC stack targeted at mobile applications. These require a stack that is compact, power dense, robust and easy to fit in a system. At present, spring 2009, a thermally insulated 80 cell stack based on 12x12cm footprint can produce 2,3kW, has a volume of 6,1 litres and weighs 8,8kg. The paper reviews the present performance.
Performance Map of the Staxera Integrated Stack Module with Partly Internal Reforming
Authors: Kluge Stefan , Posdziech Oliver , Mai Bjoern E. , Lawrence Jeremy
Published: September 2009

The present paper describes the investigation of a 1 kWel Integrated Stack Module (ISM) operated with reformate from a steam reforming process. It could be shown that no performance losses occur compared to a synthetic CPOX mixture even when high rates of internal reforming were employed. High thermal gradients that are expected to be present at the location of reforming were not observed to affect either the performance or the mechanical stability of the stack. The stack was operated in counter-flow and co-flow arrangements without showing differences in the performance. Use of internal reforming significantly reduces the air flow required for cooling the stack, which decreases parasitic power losses. The high potential of the ISM stands out above all in part load, where fuel utilizations of more than 80 % could be achieved.
Development of Disk-Type Intermediate Temperature Solid Oxide Fuel Cell by KEPCO & MMC
Authors: Nishiwaki Futoshi , Kinugasa Akira , Kato Masaki , Inagaki Toru , Hirata Katsuya , Sato Motoki , Eto Hiroyuki
Published: September 2009

The Kansai Electric Power Co., Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been jointly developing disk-type intermediate temperature solid oxide fuel cells (IT-SOFC) with lanthanum gallate-based electrolyte, since FY 2001. As of FY2004, 10 kW-class modules and a CHP system were developed under a project supported by New Energy and Industrial Technology Development Organization (NEDO). In FY 2006, a 10 kW-class CHP system using town gas as fuel was manufactured and the performance test of the system was carried out. And the first long-term stability test for 3,000 hrs was carried out in FY 2007. Furthermore, after making further refinements to enhance the performance of the 10 kW-class module, the second long-term stability test for 3,000 hrs was carried out in FY 2008. In parallel, development of high-power IT-SOFC with high power density cells started with the aim of cost reduction. The IT-SOFC single stack module was designed as to compose of 32 cells to produce 3 kW DC output. Furthermore, start-stop and cyclic loading tests were carried out under a separate NEDO project.
Co-generation of Electricity and Syngas under Electrochemical Partial Oxidation using Novel SOFCs
Authors: Kim Ilwon , Pillai Manoj , McDonald Nikkia , Shastry Tejas , Barnett Scott
Published: September 2009

Generation of syngas from natural gas is an important process in industry, because syngas is a popular precursor for production of variety of different chemicals. Currently, syngas is produced by steam or partial oxidation reforming. Electrochemical Partial Oxidation (EPOX) is a novel process where fuels like methane and natural gas, are partially oxidized under SOFC operation to co-generate electricity and syngas. In the view point of SOFC commercialization, such process could significantly off-set the manufacturing costs of SOFC generators, due to production of valuable syngas during the life of the generators. We have previously demonstrated high electrical power densities and syngas generation rates under EPOx operation using Ni-YSZ button cells. In this work, SOFCs featuring novel fuel barriers are used for EPOX operations. These SOFCs are well suited for EPOx due to their stable performances under direct hydrocarbon fueled operations and relatively high performances under intermediate temperatures. Flattened tubular design of SIS-SOFC in particular, would potentially simplify product gas collection compared to planar designs. The results on electrical tests and exhaust gas analysis using differentially pumped mass spectroscopy are presented. The effects of reforming catalysts, addition of steam or CO2 in the fuel stream are discussed. Finally the stability under long term testing are presented.
Chemically Assisted Hydrogen Generation through Oxygen Ion Conducting MIEC Membranes
Authors: Wang Haibing , Eriksen Ryan S. , Gopalan Srikanth , Pal Uday B.
Published: September 2009

Mixed ionic and electronic conducting (MIEC) membranes of Gd-doped CeO2 and Gd-doped SrTiO3 have been employed to generate and separate hydrogen. In this process steam at high temperatures is fed to one side of the MIEC membrane and a hydrocarbon feed or reformate to the other side. Hydrogen is formed through the splitting of steam on the steam side of the membrane. Oxygen is transported through coupled transport of oxygen ions and electrons to the other side of the membrane where it reacts with hydrocarbon or reformate to form products of combustion. Once the residual steam is condensed on the steam side, a feed of pure hydrogen is obtained.
Evaluating SOFC-based Power System Concepts for Unmanned Undersea Vehicles
Authors: Braun Robert , Kattke Kyle
Published: September 2009

System concepts for powering an unmanned undersea vehicle (UUV) with a solid oxide fuel cell (SOFC) power generator are developed and evaluated through modeling studies of variations in system configurations and design parameters. System concepts that meet the continuous electrical loads for sustained operations and mission selectable capabilities for a 21-inch (53.3 cm) diameter UUV platform with 500 W to 1500 W power requirements were analyzed. Two primary system concepts fueled with a liquid hydrocarbon fuel (dodecane) and employing either liquid-oxygen (LOx, Concept I) or a mixture of hydrogen peroxide and water as the cathode gas oxidant (Concept II) were generated and optimized to obtain maximum mission endurance within the volume constraints allocated for the power generator. Concept I (LOx) 'best' and 'intermediate' designs achieve system efficiencies of 47% and 42.2%-LHV, and mission durations of 90-h and 81-h, respectively, at 1000 W power with hull-integrated oxidant storage. The Concept II system manages an efficiency of 45.5%-LHV and a mission duration of 46-h.
From Energy Policies to Active Components in Solid Oxide Fuel Cells: State-of-the-Art and the Way Ahead
Authors: Aarva Anja , McPhail Stephen J. , Moreno Angelo
Published: September 2009

Based on a short review of current state-of-the-art materials of SOFC active components, the major challenges still requiring basic research are pointed out. With the aid of literature research, SWOT analyses for both main cell designs, tubular and planar, are constructed to give an immediate insight of the complex situation of SOFC research. The results of this work are interpreted with the research strategy of the European Hydrogen & Fuel Cell Technology Platform in order to incorporate the conclusions into a wider context. This study provides a clear-cut starting point for new players in the field of SOFC research, as well as tangible material for decision makers to formulate their guidelines for future strategies.
Medium Temperature Solid Oxide Fuel Cells Based on the Micro-Meso-Macro-Porous Cathodes and Anodes
Authors: Lust Enn , Kivi Indrek , Küngas Rainer , Tamm Kadi , Möller Priit , Samussenko Anton , Anderson Erik , Kurig Heisi , Nurk Gunnar
Published: September 2009

A series of electrochemical impedance experiments have been carried out in order to investigate the effect of cell chemical composition on the determination of electrochemical characteristics of strontium-doped rare earth cobaltite cathodes. The impedance responses at different electrode potentials of the half-cell and symmetric single-cell setups are compared and analyzed by the equivalent circuit modeling method. The deconvolution of impedance spectra for single cells has been achieved by differential derivative of impedance real part versus ac frequency plot analysis method. The performance of electrolyte-supported Ni/Ce0.9Gd0.1O2-δ|Ce0.9Gd0.1O2-δ|Ln0.6Sr0.4CoO3-δ symmetric single-cells has been optimized for anode diffusion layer porosity, anode functional layer starting powder specific surface area (SBET,powder), and cobaltite-based cathode material composition in a single designed experiment according to the so-called response surface methodology. The combination of electrochemical impedance spectroscopy, equivalent circuit fitting, and mathematical statistics methods proved to be a powerful tool for interpreting solid oxide fuel cell data.
Effects of Clamping Load on the Thermal Stress Distribution in a Planar SOFC with Compressive Sealing
Authors: Lin Chih-Kuang , Huang Ling-Hao , Chiang Lieh-Kwang , Chyou Yau-Pin
Published: September 2009

Finite element analysis (FEA) was conducted in this study to characterize the effects of clamping load on the thermal stress distribution in a planar solid oxide fuel cell (pSOFC) stack with compliant mica-based seal gaskets. Five different compressive loads (0.06, 0.1, 0.6, 1, and 6 MPa) were applied in the modeling to clamp the given pSOFC stack. Simulation results indicate that increasing the applied clamping load from 0.06 to 0.6 MPa could eliminate bending deformation in the positive electrode-electrolyte-negative electrode (PEN) assembly plate and its supporting frame. For a further increase of the applied clamping load to 1 and 6 MPa, the critical stresses in the glass-ceramic and mica sealants increased to a potential failure level. Thus, a 0.6-MPa clamping load is considered an optimal assembly load that can both eliminate bending deformation in the PEN-frame assembly plate and maintain acceptable critical stresses in the glass-ceramic and mica sealants.
Thermal Analysis of a Microtubular Solid Oxide Fuel Cell Using Electrochemical Impedance Spectroscopy
Authors: Nakajima Hironori , Konomi Toshiaki , Kitahara Tatsumi
Published: September 2009

A thermal analysis of the anode, cathode and electrolyte of a practical solid oxide fuel cell (SOFC) is performed. Electrochemical impedance spectroscopy with two-electrode set-up is employed on an anode-supported micro tubular SOFC. This cell is an intermediate temperature SOFC composed of an Ni/(ZrO2)0.9(Y2O3)0.1 cermet anode, an La0.8Sr0.2Ga0.8Mg0.2O2.8 electrolyte, and an (La0.6Sr0.4)(Co0.2Fe0.8)O3 cathode. A common equivalent circuit is applied to impedance spectra to acquire the resistances at the anode and cathode, and the cell Ohmic resistance. By numerically integrating these resistances, overpotentials are evaluated. The overpotentials and entropy balances, i.e., the single electrode Peltier heats, at the anode and cathode give individual heat production rates. By analytically integrating energy balance equations incorporating the heat production rates, temperatures at the anode and cathode surfaces are obtained and agree well with those measured with thermocouples.
Uncertainty Analysis in SOFC Performance Testing
Authors: Momma Akihiko , Takano Kiyonami , Tanaka Yohei , Kato Tohru
Published: September 2009

Uncertainties of the measured power at the rated condition and I-V characteristics at a given condition in SOFC performance testing were evaluated. The uncertainties were estimated mainly from the accuracy of measurement instruments using sensitivity coefficients obtained experimentally and combined to get the final results according to the law of propagation of uncertainty. Evaluated uncertainty was found to become large when the fuel utilization became larger than 70% because the dependency of cell voltage on fuel flow rate becomes large in this region.
Development of Reformate-Model-Gas Generator for SOFC Testing
Authors: Tanaka Yohei , Kato Ken , Negishi Akira , Nozaki Ken , Kato Tohru
Published: September 2009

Cell(s) voltage and power density of solid oxide fuel cell (SOFC) depend on testing conditions such as gas composition and flow-rate and operated temperatures as well as cell materials and designs themselves. A safe and precise method was developed to generate reformate-model-gases corresponding to various raw fuels of SOFC system (CH4, kerosene, diesel etc.) and reforming reactions at wide range of S/C, O2/C, and temperatures. It was confirmed that the reformate-model-gases can be precisely produced over a Ni catalyst using H2-O2-CO2-(N2) or H2-CH4-CO2-N2 mixtures as feedstock. Flow-rate calibration of the feedstock could realize uncertainties of the model-gas compositions and flow-rates at a level of {plus minus}1.0 mol.% for H2 and H2O, {plus minus}0.5 mol.% for CO, CO2, and CH4, and {plus minus}1.1% for total flow-rate of the model reformates.
Development of Testing ZIG for Tubular SOFC Cell
Authors: Choi Hoon , Jee Youngseok , Lah Seyun , Cha Sukwon
Published: September 2009

The lab scale tubular cell for testing has thermal expansion and sealing problems. When we feed fuel gas to jig inlet, ceramic glue sealant has amount of gas expansion pressure, because temperature of feeding gas changes ambient temperature to high temperature (700~900°). Furthermore, when we carry out long time test, something like degradation test, crack of ceramic glue sealant due to weakness of mechanical properties can make stop working the test. To solve these problems, we developed advanced jig design. In the advanced jig, mica is employed as spacer for sealant and insulator. Inconel springs provide appropriate pressure to mica sealant between end plate and tubular cell. It can simply fasten assembling nut with suitable torque wrench. One of the important advantages of self-compressing jig is effortless of assembling jig and tubular cell. Additionally, we reduce setting process for assembling.
A Correction for Impedance Measurements using the Three Point Electrode Technique in SOFCs
Authors: Escobar Jose A. , Pakalapati Suryanarayana , Celik Ismail B. , Finklea Harry
Published: September 2009

In this study, the effectiveness of three-point electrode (reference electrode) configuration in correctly dividing the cell impedance into contributions from the two electrodes is investigated using numerical simulations of the electric potential distribution inside typical anode-supported SOFC button cells. A computer code was developed in order to calculate the complex, two dimensional potential field. The apparent electrode impedance measured by a reference electrode is obtained from the potential fields calculated at different frequencies. Impedance calculations show that the reference electrode configuration does not effectively isolate the impedances for the anode and cathode electrodes in an anode-supported cell. The general behavior of the impedance calculations is studied for several cases with different physical parameters such as electrode resistance and capacitance. This study proposes a correction method for the impedance calculations in order to eliminate the errors brought by the cell geometry.
Generalization of Degradation Mechanisms in Terms of Materials Chemical Nature, Operation Condition and Electrode Reaction Mechanisms
Authors: Yokokawa Harumi , Kishimoto Haruo , Yamaji Katsuhiko , Horita Teruhisa
Published: September 2009

Present status of investigations on degradation mechanism, acceleration test and forecasting life time within NEDO SOFC project will be reported with an emphasis on the physicochemical understanding of degradation and reasoning for technique of predicting lifetime. Physicochemical understanding is based on the local equilibrium model in the vicinity of electrochemical reactions sites. This makes it possible to treat systematically the mechanical instability, chemical reactivity, and electrochemical degradation in a long period of time.
Durability of Anode-supported SOFCs Stack using La(Ni,Fe)O3 Cathode
Authors: Yoshida Yoshiteru , Komatsu Takeshi , Chiba Reiichi , Yokoo Masayuki , Hayashi Katsuya , Orui Himeko , Arai Hajime
Published: September 2009

The Durability of a power generation unit composed of an anode-supported SOFC with a La(Ni,Fe)O3 cathode and uncoated metallic interconnects was measured. A high electrical conversion efficiency of 60% (LHV) was obtained for more than 7000 h. A thermal cycling test was conducted at t = 1500 h and little decay was observed. During the test the cell voltage decreased gradually after t = 5000 h. The cell voltage reduction was 0.5% per 1000 h. Resistance changes in the power generation unit were analyzed with impedance spectroscopy. The cathode polarization resistance and ohmic resistance both increased with time. The elements Si and B contained in the water that condensed from the anode exhaust gas were identified using inductively coupled plasma (ICP).
In-situ Electrochemical Characterization of SOFC cell Degradation: The Cases of Mechanical Damage and Carbon Deposition
Authors: Laurencin Jérôme , Girona Kelly , Delette Gérard , Lefebvre-Joud Florence
Published: September 2009

A methodology has been proposed to analyze the electrochemical degradation of the ASC configuration. This methodology, based on the measurement of the cell response by impedance spectroscopy, has been applied to study the cell performances degradation, (i) when the anode is re-oxidized under an ionic current, and (ii) upon direct methane reforming. In the first case, a thin cermet layer growing from the anode/electrolyte interface has been oxidized and then reduced. This 'redox' cycle has been repeated until the complete degradation of the cell. It has been found that the impedance diagram's evolution is consistent with a delamination between the ACC/AFL interface. In the second case, the cell has been operated under methane conditions known to favour the coking. The analysis of the impedance diagrams has shown a degradation of the current collection. This result has been found to be consistent with the location of carbon deposit inside the cell.
Effect of Humidity in Air on Performance and Long-Term Durability of SOFCs
Authors: Hagen Anke , Chen Ming , Neufeld Kai , Liu Yi-Lin
Published: September 2009

Anode supported SOFCs based on Ni-YSZ anodes, YSZ electrolytes, and LSM-YSZ cathodes were studied with respect to durability in humid air (~4%) over typically 1500 hours. Operating temperature and current density were varied between 750 and 850 oC and 0.25-0.75 A/cm2, respectively. It was found that the introduction of humidity affected the cell voltage under polarization of the cell and that this effect was (at least partly) reversible upon switching off the humidity, probably related to a segregation of impurities towards the three phase boundary in the presence of humidity. Generally, the studied cells were successfully operated in humid air under technologically relevant conditions. Improvements at the cathode/electrolyte interface made it possible to obtain highly stable cells, which can be operated under high current density and at 750 oC in humid air - conditions that are known to cause significant cell voltage degradation in dry air.
Electrochemical Degradation of Fuel Cells: Effect of Electrolyte Composition
Authors: Lim Hyung-Tae , Virkar Anil V.
Published: September 2009

Recently, a model for SOFC stack degradation when a cell begins to operate under a negative voltage due to 'cell imbalance' was presented. Subsequently, experimental evidence for degradation was presented by investigating cell (stack) failure mechanism. When operated under a negative voltage of a sufficient magnitude, anode/electrolyte interface delaminated. The model shows that electronic conduction through the electrolyte plays a significant role. In the present work anode-supported cells were made of two different electrolyte compositions: (a) 8YSZ, (b) 92% 8YSZ + 8% CeO2 (8CYSZ). It was observed that when operated under a negative voltage, the cell with 8YSZ exhibited considerable degradation attributed to electrolyte/anode interface delamination. By contrast, the cell with 8CYSZ exhibited no degradation under similar testing conditions. Results are explained on the basis of electronic conduction and the previously described degradation model.
Classification of Mechanical Failure in SOFC and Strategy for Evaluation of Operational Margin
Authors: Kawada Tatsuya , Watanabe Satoshi , Hashimoto Shin-ichi , Sakamoto Tadashi , Unemoto Atsushi , Kurumatani Mao , Sato Kazuhisa , Iguchi Fumitada , Yashiro Keiji , Amezawa Koji , Terada Kenjiro , Kubo Momoji , Yugami Hiroo , Hashida Toshiyuki , Mizusaki Junichiro
Published: September 2009

Mechanical damages and their formation mechanisms in SOFC were investigated. Generalized schemes of the occurrence of mechanical failures were summarized, and among them, common features in various cell designs were extracted. They were discussed in three categories of (a) deformation of a cell due to its asymmetry, (b) propagation of mechanical defects, and (c) effects of irregular operations. Prototype-cell experiments were designed to reproduce the key features, and to develop a quantitative evaluation scheme of operational margins for prediction of the short and long term reliability of a specific cell design. Numerical calculation tools based on finite element method and homogenization method are designed. Experimental methods were developed to acquire high-temperature mechanical behaviors of the materials and cell stacks.
2R-Cell{trade mark, serif}: Reliability of Anode Supported Thin Electrolyte Upon Multi Thermo and Redox Cycles
Authors: Ihringer Raphael
Published: September 2009

Because of their high power density in a wide range of temperature, anode supported thin film electrolytes are nowadays the mostly used cells in the SOFC area. Unfortunately, the latter suffer from an important problem that remained unsolved till today: they are totally destroyed when re-oxidation occurs in the anode chamber. This happens, for instance when fuel supply inappropriately stops. Cell peripheral re-oxidation is another well known figure where failures are initiated. In all cases, when re-oxidation starts, the stack quickly undergoes a fatal destruction and the SOFC system definitely falls down. Fiaxell Sàrl, a new company active in the SOFC area has developed a novel anode supported thin electrolyte, the 2R-Cell{trade mark, serif} that provides robustness and reliability upon multi thermo and redox-cycles. Such cells have now demonstrated for thousands of cumulated hours that they withstand full redox-cycles without any failure in the anode substrate neither in the thin electrolyte.
Development and Performance of Planar SOFC Stacks
Authors: Guan Wanbing , Zhai Huijuan , Li Fanghu , Li Zhi , Xu Cheng , Wang Wei Guo
Published: September 2009

Stacks are made of conventional single cells with configuration of Ni-YSZ/YSZ/LSM-YSZ. Thermal cycling, degradation and power density are investigated. A cell stack unit showed a degradation rate of less than 1%/per cycle and maintained 1.15 volt of OCV after going through 1350 hours and 46 thermal cycles under 0.1A/cm2 and 750°. The OCV of two-cell stack was above 2.2V after 400 hours operation time and 15 thermal cycles under 0.1Acm-2. The degradation of two cell stack was also lower than 1% per cycle. A five cell stack has been tested for more than 3000 hours in which the individual stack unit is monitored. Our 10 cell stack reached 310W with 0.31W/cm2 in power density. The single cell could reach 50 W power in the current stack design which corresponds to our results from single cell test with active area of 4×4cm2. A stack of 550W was built and tested.
Development of SOFC Performance and Durability Evaluations Technology
Authors: Yamamoto Tohru , Morita Hiroshi , Yoshikawa Masahiro , Yoshiba Fumihiko , Asano Koichi , Yasumoto Kenji , Mugikura Yoshihiro
Published: September 2009

Development of the performance and durability evaluation technology is necessary to design a SOFC system and to understand behaviors of cell and stacks. So we, Central Research Institute of Electric Power Industry (CRIEPI), have operated several types of SOFCs in order to develop the performance equation which can represent cell performance by a simple measurement of cell voltage as a function of operation temperature and partial pressure of supplied gasses. As the result, it has been clarified that the behavior of cathode polarization under various conditions is described by dependence of PO2^(-0.5), and the behavior of anode is different according to each type of SOFCs.
Effect of High Current Loading on the Performance Enhancement of SOFCs
Authors: Murakami Kota , Muroyama Hiroki , Matsui Toshiaki , Kikuchi Ryuji , Eguchi Koichi
Published: September 2009

Solid Oxide Fuel Cells (SOFCs) with a conventional configuration, Ni-YSZ | YSZ | LSM, exhibit a continuous improvement of performance during the operation for initial several tens hours to several weeks until the cathode is completely activated for oxygen reduction. However, the power generation performance is requested to be stable in a short period of time for the practical application. In this study, we investigated the effect of high current loading on the stabilization of cell performance. The time course of terminal voltage was recorded at high current densities, where the cell operated as an oxygen pumping. The terminal voltage abruptly increased at first current loading and then achieved a stable value within several hours. The termination of performance enhancement in fuel cell operation by this current treatment was confirmed. No degradation by loading the current density up to 5.0 A/cm2 for a short time was confirmed in the impedance of both electrodes.
A Novel Co-firing Process for Multi-layers of Solid Oxide Fuel Cells
Authors: Han Min-Fang , Li Zhen , Le Hui-Rong , Shao Wu
Published: September 2009

The major challenge for the commercialization of SOFCs is to reduce high manufacturing costs. By simplifying the sintering process and reducing the sintering temperature in the fabrication process, the manufacturing costs of SOFC could be lowered significantly. A low-temperature co-firing process for three layers of SOFC including cathode (LSM/YSZ, [LSM:(La,Sr) MnO3),YSZ:Y2O3-ZrO2]), electrolyte(YSZ) and anode (YSZ/NiO) has been developed. The anode substrate of NiO/YSZ was formed and pre-sintered at 1000 ° for 2 hours, then the YSZ electrolyte layer and LSM/YSZ cathode layer were deposited successively, and finally the anode-supported SOFCs were fabricated by co-firing at 1200 ° for 5 hours. In order to minimize the mismatch in sintering shrinkage among the components of the cell, various amounts of pore former were added to the anode and cathode layers. The mismatch in sintering shrinkage is minimized by adding 15wt% of pore former to the anode and 20wt% to the cathode. The OCV of the co-fired anode-support trilayer cell was 1.05V at 800 °. The power density of this cell was 0.47W/cm2 at 800°.
Improvement on the Microstructure and Electrochemical Performance of Cathode-supported Tubular Solid Oxide Fuel Cells
Authors: Zhao Chunhua , Liu Renzhu , Wang Shao Rong , Wen Ting Lian
Published: September 2009

The effects of fabrication parameters for dip-coating and co-sintering techniques on the microstructure and electrochemical performance of cathode-supported tubular solid oxide fuel cells were discussed in detail. In comparison with starch as pore former of cathode, graphite is more apt to produce uniform opened-pores. The addition of graphite powder to cathode can not only creates pores but also improves its shrinkage. By choosing 20 wt% graphite powder as pore former and 1260 {degree sign}C as co-sintering temperature, the maximum power density of 0.43 W cm-2 can be reached at 850 {degree sign}C with humidified H2 as fuel and O2 as oxidant.
Effect of Nano Ion Conductor Infiltration on the Performance of Anode Supported Solid Oxide Fuel Cells
Authors: Timurkutluk Cigdem , Timurkutluk Bora , Mat Mahmut D. , Kaplan Yuksel , Ibrahimoğlu Beycan , Pamuk Ibraim
Published: September 2009

A high performance anode supported solid oxide fuel cell (SOFC) is developed by low-cost tape casting, co-sintering and nano-ion conductor infiltration techniques. The mixture of gadolinium and cerium nitrate solution is infiltrated into both anode and cathode layers and fired at a temperature that gadolinium nitrate and cerium nitrate undergoes a solid state reaction and forms nano ion conductor phase in both electrodes. The effect of molar concentrations and firing temperature of nano ion conductor phase on the cell performance are investigated. The measurements show that nano-sized ion conductor infiltration significantly improves the cell performance. The cell provides 1.718Wcm-2 maximum power density at an operation temperature of 750{degree sign}C. The high performance is attributed to increase in the oxide ion conductivity and three phase boundaries of both anode and cathode layers by nano ion-conductor infiltration.
Novel Procedures for the Microstructural Design of SOFC Materials
Authors: Ruiz-Morales Juan Carlos , Savvin Stanislav , Núñez Pedro , Peña-Martínez Juan , Canales-Vázquez Jesús , Marrero-López David , Roa Joan Josep , Segarra Mercè
Published: September 2009

Here we report two novel procedures that may lead to enhanced efficiencies of a SOFC via a precise control of the electrode microstructure and through the fabrication of a new type of electrolyte-supported SOFC. The first route is a simple and cost-effective method that allows the material-engineering for creation of a 2D/3D matrix of cross-linked channels through the whole SOFC electrode materials. The size of the channels can be precisely tailored from few microns up to hundreds of microns and remains stable up to 1500ºC. Due to the versatility of the method proposed it can be applied to practically any type of material commonly used in SOFC technology or in other fields. The second route is a novel design, alternative to the conventional electrolyte-supported SOFC with a honeycomb-electrolyte fabricated from hexagonal cells, providing high mechanical strength to the whole structure and supporting the thin layer used as electrolyte of a SOFC. The main feature of this design is the reduction of ~70% of the support material, rendering volumetric power densities of 1.22 W/cm3 and a high OCV of 1.13 V under pure CH4 at 900 ºC using standard SOFC materials
Fabrication of Proton Conducting Solid Oxide Fuel Cells by using Electrophoretic Deposition
Authors: Di Bartolomeo Elisabetta , Zunic Milan , Chevallier Laure , D'Epifanio Alessandra , Licoccia Silvia , Traversa Enrico
Published: September 2009

Anode-supported proton conducting solid oxide fuel cells (SOFCs) were fabricated by using electrophoretic deposition (EPD) for the electrolyte film deposition. BaCe0.9Y0.1O3-δ (BCY10) thick films were deposited on NiO-BCY10 substrates. The influence of the EPD parameters on the microstructure and electrical properties of BCY10 thick films was investigated. The anode substrates and electrolyte deposits were co-sintered at 1550{degree sign}C for 2 h to obtain a dense electrolyte thick film, while keeping a suitable porosity in the anode. Innovative composites with La0.8Sr0.2Co0.8Fe0.2O3 (LSCF)-BaCe0.9Yb0.1O3-δ (10YbBC) composition were used as cathode materials. Prototype SOFCs were prepared by depositing the composite cathode on the co-sintered half cells. Fuel cell tests and electrochemical impedance spectroscopy (EIS) measurements were performed in the 550-700ºC temperature range. The maximum power density of 296 mW cm-2 was achieved at 700{degree sign}C.
SOFC Powders and Unit Cell Research at NIMTE
Authors: Wang Jian Xin , Shao Jing , Tao You Kun , Wang Wei Guo
Published: September 2009

(La0.75Sr0.25)0.95MnO3{plus minus}δ(LSM), (La0.6Sr0.4)0.9Co0.2Fe0.8O3-δ(LSCF), La0.6Sr0.4CoO3−δ(LSC), Ce0.9Gd0.1O1.95(CGO) nano-powders and LSM+YSZ, LSCF+CGO, LSC+CGO composite cathodes have been researched at Ningbo Institute of Material Technology & Engineering (NIMTE), Chinese Academy of Sciences and reported in this paper. Microstructure characterizations and electrical properties measurement showed these resultant powders are high purity, single phase, slight aggregation with grain size less than 100 nm and high performances. Excellent polarization resistance of 0.18Ω.cm2 at 750{degree sign}C, 0.12Ω.cm2 at 700{degree sign}C, 0.12Ω.cm2 at 650{degree sign}C were obtained respectively in the LSM+YSZ/YSZ/LSM+YSZ, LSCF+CGO/CGO/LSCF+CGO and LSC/CGO/YSZ/CGO/LSC symmetric cells. Anode supported Cells with configuration of Ni+YSZ/YSZ/LSM+YSZ, Ni+YSZ/YSZ/CGO/LSCF+CGO and Ni+YSZ/YSZ/CGO/LSC+CGO exhibited the maximum power density of 0.63W/cm2 at 750{degree sign}C, 0.54W/cm2 at 700{degree sign}C and 0.42W/cm2 at 650{degree sign}C (H2/air, active electrode area of 4X4 cm2), respectively. These results indicated that the YSZ-based anode supported cells with LSM-YSZ, LSCF-CGO, LSC-CGO composite cathode have the feasibility to be operated at 750-650{degree sign}C with an acceptable power density.
Process Development for Nanostructured Functional Layers by Liquid Injection Plasma Spraying for Solid Oxide Fuel Cells
Authors: Soysal Dennis , Christenn Claudia , Ansar Asif
Published: September 2009

Development and progress to produce nanostructured solid oxide fuel cells by liquid injection plasma spraying is presented. Two different ways to create nanostructured functional layers by plasma spray are discussed. Firstly in suspension plasma spraying (SPS) nanopowders are injected into the plasma in a solvent. The second method presented is solution precursor plasma spraying (SPPS) that injects liquid precursors into the plasma flame. Metallographic cross sections and SEM images of fractured coatings show the differences in microstructure of these coating techniques. SPPS has its advantages in high stoichiometric flexibility and high porosity. SPS produces dense layers most appropriate for thin electrolytes and also highly porous coatings with a high specific surface area. The deposition efficiency (DE) of different injection techniques is shows that impulse of injected droplets has a great influence. Both techniques have tremendous potential for high performance SOFCs.
Materials Development for SOFC Applications
Authors: Seabaugh Matthew M. , Day Michael , Beachy Michael , McCormick Buddy E. , Ibanez Sergio
Published: September 2009

As solid oxide fuel cell technology enters product commercialization, low cost manufacturing and long-term stability of SOFC is critical to the success in the industry. Materials that can be produced in a scalable manner and simply integrated into stack manufacturing are important to achieve these goals. In this paper, materials evaluations of low temperature cathodes, interconnect coatings and contact paste development are reviewed.
Thick-Film Electrolyte-Supported Solid Oxide Fuel Cells For Rapid Thermal Cycling
Authors: Joo Jong Hoon , Choi Gyeong Man
Published: September 2009

The rapid thermal-cycling tests of thick-film electrolyte-supported SOFCs (solid oxide fuel cells) were performed. The sintered 50μm thick YSZ (yttria-stabilized zirconia) electrolyte film was mounted on 2mm-thick YSZ ring by sintering two pieces together. With this new configuration, it was possible to test rapid thermal-cycling between 100oC and 800oC with heating and cooling rates of 50oC/min. Using LSCF (La0.6Sr0.4Co0.2Fe0.8O3−δ) as a cathode and Ni-GDC (Gd-doped ceria) as a composite anode, the cell with 50μm thick YSZ electrolyte achieved a high performance, i.e. the maximum power density of 510 mW/cm2 at 800oC after cycling tests. This investigation demonstrates that it is possible to use a planar SOFC when high heating or cooling rate is required.
Fabrication of Tri-layered Structrure for Solid Oxide Fuel Cells by Electrophetic Depositions
Authors: Tsai Ho-Cheng , Chang Yung-Tse , Wu Pu-Wei , Lin Pang
Published: September 2009

A tri-layered ceramic structure was prepared by consecutive electrophoretic depositions of anode, electrolyte, and cathode, followed by a single sintering process to fabricate solid oxide fuel cells. Materials characterizations including SEM and XRD were carried out along with electrochemical analysis.
Influence of Thermal Treatment During Cell Manufacturing on the Performance of Tape Cast Solid Oxide Fuel Cells
Authors: Schafbauer Wolfgang , Menzler Norbert H. , Buchkremer Hans Peter
Published: September 2009

Recently, the standard manufacturing route for solid oxide fuel cells has been changed from warm pressing of the anode substrate of Coat Mix® powders towards tape casting of a mixture of yttria stabilized zirconia and nickel oxide to the anode substrate. Due to different shrinkage behavior, especially heat treatment steps and several coating parameters had to be adjusted to the new substrate type. In this contribution, the influence of different processing parameters during manufacturing on the performance of single cells is discussed.