Solid Oxide Fuel Cell Development at Forschungszentrum Juelich

Blum, Ludger; Buchkremer, H.P.; Groß, Sonja M.; Gubner, Andreas; Haart, L.G.J. de; Nabielek, H.; Quadakkers, W. J.; Reisgen, U.; Smith, Martin J.; Steinberger‐Wilckens, Robert; Steinbrech, R. W.; Tietz, Frank; Vinke, Izaak C.

doi:10.1002/fuce.200600039

Cited by 68 publications

(47 citation statements)

References 6 publications

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“…Voltage of the cell #1 (bottom cell) was 50-100 mV lower compared to the other cells, and shortcircuit was measured in the cell #8. The other cell voltages were within ±25 mV and similar values have been reported previously for FZJ stacks [23]. A slight increase in the voltage is observed towards the top of the stack, which is probably caused by the heating effect of the furnace, and due to the heat loss through the ceramic bricks at the bottom of the furnace.…”

Section: Performance and Durability Of The Stacksupporting

confidence: 81%

Experimental Analysis on Performance and Durability of SOFC Demonstration Unit

et al. 2010

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A technical description and experimental analysis of a SOFC demonstration unit is presented. The unit contains most of the primary BoP‐components of a complete SOFC system, except of air and fuel recirculation equipment or fuel system compressor. Natural gas is used as the fuel and electricity is supplied to the electric grid. A 5 kW power class planar SOFC stack from Research Centre Jülich is assembled to the demo unit and a long‐term experiment is conducted to assess the characteristic performance and durability of different components of the unit (e.g. the SOFC stack, the fuel pre‐reformer and air heat exchangers). The evolution of absolute voltage drop of the stack over time is found to be of the same magnitude when compared to short stack experiments. Thus, other system components are not observed to cause an increase in the characteristic voltage drop of the stack. Two BoP‐components, the afterburner and the power conversion unit failed to operate as designed. The performance of other BoP‐components i.e. fuel pre‐reformer and heat exchangers were satisfactory during the test run, and no significant performance loss could be measured.

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Section: Performance and Durability Of The Stacksupporting

confidence: 81%

Experimental Analysis on Performance and Durability of SOFC Demonstration Unit

et al. 2010

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“…The choice of materials, i.e., Ni and ScSZ, is particularly indicated for operation at intermediate temperature, 60,61 which is set to 973 K. The thickness of the electrolyte, made of ScSZ, is set to 10 μm, which is typical for anode-supported planar SOFCs. 2,32,62,63 Material-specific and microstructural properties were evaluated by Bertei et al 39 Although the absolute value of the results depends on the choice of this specific set of parameters, the emergent trends and the scaling laws discussed afterwards are general and highly applicable to a wide range of conditions and materials. Figure 2 shows the current density predicted by Eqs.…”

Section: Resultsmentioning

confidence: 99%

Guidelines for the Rational Design and Engineering of 3D Manufactured Solid Oxide Fuel Cell Composite Electrodes

Bertei

Tariq

Yufit

et al. 2016

J. Electrochem. Soc.

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The growth of 3D printing has opened the scope for designing microstructures for solid oxide fuel cells (SOFCs) with improved power density and lifetime. This technique can introduce structural modifications at a scale larger than particle size but smaller than cell size, such as by inserting electrolyte pillars of ∼5-100 μm. This study sets the minimum requirements for the rational design of 3D printed electrodes based on an electrochemical model and analytical solutions for functional layers with negligible electronic resistance and no mixed conduction. Results show that this structural modification enhances the power density when the ratio k eff between effective conductivity and bulk conductivity of the ionic phase is smaller than 0.5. The maximum performance improvement is predicted as a function of k eff . A design study on a wide range of pillar shapes indicates that improvements are achieved by any structural modification which provides ionic conduction up to a characteristic thickness ∼10-40 μm without removing active volume at the electrolyte interface. The best performance is reached for thin (<∼2 μm) and long (>∼80 μm) pillars when the composite electrode is optimised for maximum three-phase boundary density, pointing toward the design of scaffolds with well-defined geometry and fractal structures. Many studies in the literature have recognised the importance of the electrode microstructure in affecting the power density and the lifetime of solid oxide fuel cells (SOFCs).1-7 Significant enhancements in power density have been achieved through the statistical control of the microstructural properties by tuning porosity, 8,9 volume fractions, 2,8,10 particle size 11-13 and even tortuosity of the phases.14 However, nowadays the design of the electrode microstructure can be optimised with unprecedented precision through the advent of 3D printing and additive manufacturing techniques. 15-17Additive manufacturing allows for the development of electrodes with 3D architectures, thus going beyond what conventional fabrication techniques, such as tape casting and screen printing, can produce. The exploitation of 3D additive manufacturing has been successfully applied by the battery community [18][19][20] and the implementation of this approach to SOFCs is currently under investigation.15,21 One of the most promising applications consists of the insertion of ionconducting pillars connected to the electrolyte 15,[22][23][24][25] as reported in Figure 1. Such a modification can be regarded as the mesoscale structural control of electrode microstructure, where the term mesoscale here refers to a dimension larger than the typical constituent particle size (<1 μm) but smaller than the characteristic length of the cell, that is, falling in the order of 5-100 μm.26 Ideally, 3D printing offers the opportunity to controllably manufacture pillars of any shape, with the desired geometric and spacing requirements, in order to provide a preferential pathway for ionic conduction. 22,25 It is important to note that this mesos...

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“…This cermet anode works well under certain conditions (e.g. with internal steam-reformed methane [1]). However, in order to further simplify fuel preprocessing and to improve the reliability of the SOFC systems, the following aspects still need to be addressed.…”

Section: Introductionmentioning

confidence: 98%

Ceramic‐based Anode Materials for Improved Redox Cycling of Solid Oxide Fuel Cells

Tietz

2008

Fuel Cells

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In order to improve the reliability of anode‐supported solid oxide fuel cells (SOFCs) in terms of tolerance to redox cycles, and to minimise fuel preprocessing for the direct use of readily available hydrocarbons in SOFCs, alternative ceramic‐based anode substrate materials and functional anode materials were investigated, with the emphasis on perovskite oxides. Compared to (Sr,La)TiO3–δ and Nb2TiO7–δ, (Sr,Y)TiO3–δ ceramics (SYT, with a Y content of about 7 at.‐%) reduced at high temperatures are promising redox‐stable anode substrate materials due to their very small dimensional change upon redox cycling (0.14%). Correspondingly, the composite ceramic SYT/YSZ impregnated with ∼5 vol.‐% Ni has a good chance of being applied as a redox‐stable functional anode material due to its even smaller dimensional change upon redox cycling (<0.05%) and superior electrochemical performance for H2 oxidation (polarisation resistance ∼0.2 Ω cm2 at 800 °C). The small fraction of Ni homogeneously dispersed on the pore walls of the SYT/YSZ ceramic framework significantly enhances the electrocatalytic activity, and should not have a detrimental effect on the redox stability of the electrode. In addition, two mixed conductors with perovskite structure, (La0.8Sr0.2)0.94Al0.5Mn0.5O3–δ and La0.4Sr0.6Ti0.4Mn0.6O3–δ, were also investigated. They show promising electrochemical performance for the oxidation of H2. However, the high‐level Mn substitution which seems necessary to achieve a significant electrical conductivity and catalytic activity has a detrimental effect on the chemical stability of these two materials. Consequently, they show relatively large and irreversible chemical expansion and are thus not considered to be qualified functional anode materials.

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Solid Oxide Fuel Cell Development at Forschungszentrum Juelich

Cited by 68 publications

References 6 publications

Experimental Analysis on Performance and Durability of SOFC Demonstration Unit

Experimental Analysis on Performance and Durability of SOFC Demonstration Unit

Guidelines for the Rational Design and Engineering of 3D Manufactured Solid Oxide Fuel Cell Composite Electrodes

Ceramic‐based Anode Materials for Improved Redox Cycling of Solid Oxide Fuel Cells

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