Characterization of SOFC Short Stacks and Stacks for Mobile Applications

Lang, Michael; Auer, Corinna; Eismann, Andreas; Schiller, Günter; Szabo, Patric

doi:10.1149/1.2729077

Cited by 13 publications

(5 citation statements)

References 21 publications

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“…However, during the 800 h of long term operation with simulated reformate an overall stack degradation rate of about 4.8% / 1000 h was observed. This is in good agreement with other stacks which were operated at the same conditions (12) and with literature values (13). However, the degradation rates of the single cells during operation differ significantly from each other.…”

Section: Performance Of Sofc Short Stacks With Mixed Reformatesupporting

confidence: 93%

“…The stack reached a high electrical power of 756 W at a stack voltage of 18.9 V with a fuel utilization of 70 mol%. The average cell power density was 333 mW/cm², which is similar to former stack results (12). The corresponding individual power densities of the cells at 0.7 V were in the range of 288 mW/cm² (cell 1) and 385 mW/cm² (cell 13).…”

Section: Performance Of Sofc Stacks With H 2 + Nsupporting

confidence: 88%

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SOFC Stacks for Mobile Applications

et al. 2009

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Solid Oxide Fuel Cells (SOFCs) are gaining more and more attention as auxiliary power units (APU), e.g. for passenger cars, trucks and airplanes. In this context, the main focus is on the development of SOFC stacks, which fulfill the strong requirements for mobile applications, e.g. low weight and volume, high power densities with reformate gases and low degradation rates under dynamic operating conditions. The paper presents results of investigations of SOFC short stacks and stacks for mobile applications, which were developed by an industrial consortium. The stack design is based on stamped metal sheet bipolar plates, into which anode supported cells are integrated. The stacks were electrochemically characterized mainly by long-term measurements, by current-voltage measurements and by impedance spectroscopy. The SOFC stacks were operated at different temperatures, varying fuel gas compositions and different fuel gas flow rates. The electrochemical performance, the uniformity, the voltage losses and the degradation mechanisms of the short stacks were analyzed. Light Weight SOFC Stack DesignThe increase of electrical energy consumption on board of vehicles, e.g. passenger cars, trucks and airplanes, leads to the development of new strategies for on-board energy conversion. In this context, SOFCs are gaining more and more attention as auxiliary power units (APU). However, the requirements and the assembling of SOFC stacks for mobile applications differ significantly from those for stationary applications. Therefore, the main challenge is the development of light-weight SOFC stacks, which can be operated with high performance and reliability under dynamic operating conditions. Not many studies have been published concerning the development of SOFC stacks for mobile applications (1-6). However, none of these activities concentrate on the detailed investigation of the electrochemical behavior, e.g. voltage losses and degradation effects, of the different cells in the stacks at the different operating conditions. Therefore, at the DLR different light-weight SOFC short stacks and stacks are tested and electrochemically characterized. The stacks were developed in cooperation with several industrial partners (Ceramtec / Marktredwitz, Elring-Klinger / Dettingen, ThyssenKrupp / Essen) and the Research Center Jülich (FZJ). This design is based on the application of thin stamped metal sheet bipolar plates from Elring Klinger and anode substrate supported cells from Ceramtec, which form a cassette arrangement (Figure 1).

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Section: Performance Of Sofc Short Stacks With Mixed Reformatesupporting

confidence: 93%

Section: Performance Of Sofc Stacks With H 2 + Nsupporting

confidence: 88%

SOFC Stacks for Mobile Applications

et al. 2009

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“…, [2] with R: gas constant, T: temperature, F: Faraday constant and p: partial pressure. A list of symbols is given in Table I.…”

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confidence: 99%

“…Therefore, one of the research activities at DLR focuses on the electrochemical testing and modeling of SOFC stacks with different designs both for stationary and mobile applications. [2][3][4][5] The present paper focuses on the better understanding of the electrochemical behavior of repeat units (RU) in SOFC stacks under system relevant operating conditions. Examples of current-voltage curves of selected RUs of a 20-cell SOFC stack with different shapes and dependencies on electrical current are presented and discussed.…”

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confidence: 99%

Understanding the Current-Voltage Behavior of High Temperature Solid Oxide Fuel Cell Stacks

Lang

Bohn

Henke

et al. 2017

J. Electrochem. Soc.

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High temperature solid oxide fuel cell (SOFC) stacks are highly efficient and environmentally friendly electrochemical systems, which convert the chemical energy of fuel gases with oxygen from air directly into electrical energy. During operation of SOFC stacks under system operating conditions pronounced temperature and fuel gas composition gradients along the cell area and along the height of the stack occur. Therefore, in contrast to SOFC cells, the electrochemical behavior of SOFC stacks is much more complex and has not sufficiently been studied. Specially, a shortcoming exists in terms of understanding the homogeneity, performance loss mechanisms, and various resistances and overvoltages within the stack repeat components. Therefore, this paper focuses on the improvement of the understanding and of the interpretation of different current-voltage curves of solid oxide fuel cell stack repeat units. Three different cases are discussed: repeat units with high power performance, with high cell contact resistance and with high fuel utilization. The stacks were investigated by current-voltage curves, electrochemical impedance spectroscopy and gas analysis. In order to understand the electrochemical behavior of these three cases both experimental and modeling results are presented, compared and discussed.

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“…Issues like chromium poisoning and corrosion can cause additional losses and faster cell degradation (3). In order to study the effects resulting from MICs, different experimental setups and simulation models were proposed in the literature (4)(5)(6).…”

Section: Introductionmentioning

confidence: 99%

Towards an Impedance-Based Analysis of SOFC-Stacks

Golani,

Bausinger,

Mai

et al. 2023

ECS Trans.

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This proceeding aims to understand the performance of SOFC stacks using impedance spectroscopy. For the stack analysis, gradients over the active cell area are averaged out, preventing access to local phenomena. Hence, to get better insight into the spatial distribution of losses, single cells with an active electrode area of 1 cm² are characterized at 850 °C based on EIS and DRT-analysis. To ensure an appropriate deconvolution of processes, symmetrical anode and cathode cells are also tested. Next to the ideally contacted cells, metallic interconnecting repeat units are analyzed to study the impact of contacting and gas supply in the stack. The effect of fuel utilization was also investigated by mimicking different locations in the stack. In this contribution, the complex impedance behavior of the stack based on polarization losses will be discussed. The paper also provides disentangled information often lost or averaged out in stacks.

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Characterization of SOFC Short Stacks and Stacks for Mobile Applications

Cited by 13 publications

References 21 publications

SOFC Stacks for Mobile Applications

SOFC Stacks for Mobile Applications

Understanding the Current-Voltage Behavior of High Temperature Solid Oxide Fuel Cell Stacks

Towards an Impedance-Based Analysis of SOFC-Stacks

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