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Fast X-ray tomographic microscopy: investigating mechanisms of performance drop during freeze starts of polymer electrolyte fuel cells


Mayrhuber, Immanuel; Marone, Federica; Stampanoni, Marco; Schmidt, Thomas J; Büchi, Felix N (2015). Fast X-ray tomographic microscopy: investigating mechanisms of performance drop during freeze starts of polymer electrolyte fuel cells. ChemElectroChem, 2(10):1551-1559.

Abstract

The success of a freeze start of a polymer electrolyte fuel cell depends on the state and spatial distribution of the water produced in the porous structures of the membrane electrode assembly (MEA), namely, the gas diffusion and catalyst layers. To improve understanding of performance loss that occurs during freeze starts, the water/ice phase is imaged in the MEA by means of X-ray tomographic microscopy at temperatures between −10 and −20 °C. As the duration of the isothermal freeze starts can be as short as 20 s before a performance drop occurs, the acquisition time for one tomographic scan is reduced to only 4.9 s. Interpretation of the images and the voltage transients show three different mechanisms for the performance drop. The main difference between the three mechanisms is the lack or appearance of supercooled water in the gas diffusion layer. Fast X-ray imaging is well suited to solve this challenge.

Abstract

The success of a freeze start of a polymer electrolyte fuel cell depends on the state and spatial distribution of the water produced in the porous structures of the membrane electrode assembly (MEA), namely, the gas diffusion and catalyst layers. To improve understanding of performance loss that occurs during freeze starts, the water/ice phase is imaged in the MEA by means of X-ray tomographic microscopy at temperatures between −10 and −20 °C. As the duration of the isothermal freeze starts can be as short as 20 s before a performance drop occurs, the acquisition time for one tomographic scan is reduced to only 4.9 s. Interpretation of the images and the voltage transients show three different mechanisms for the performance drop. The main difference between the three mechanisms is the lack or appearance of supercooled water in the gas diffusion layer. Fast X-ray imaging is well suited to solve this challenge.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Biomedical Engineering
Dewey Decimal Classification:170 Ethics
610 Medicine & health
Uncontrolled Keywords:electrochemistry;fuel cells;polymers;X-ray tomographic microscopy;water chemistry
Language:English
Date:2015
Deposited On:09 Feb 2016 11:24
Last Modified:05 Apr 2016 20:00
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:2196-0216
Additional Information:Special Issue: In Situ Monitoring
Publisher DOI:https://doi.org/10.1002/celc.201500132

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