Visualization of the water distribution in perforated gas diffusion layers by means of synchrotron X-ray radiography

Markötter, Henning; Alink, Robert; Haußmann, Jan; Dittmann, Katja; Arlt, Tobias; Wieder, Frank; Tötzke, Christian; Klages, Merle; Reiter, Christian; Riesemeier, H.; Scholta, Joachim; Gerteisen, Dietmar; Banhart, John; Manke, Ingo

doi:10.1016/j.ijhydene.2012.01.141

Cited by 92 publications

(49 citation statements)

References 19 publications

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“…For compressed GDLs, liquid water takes the higher-porosity transport pathways, thus implying that GDL architectures with modulated regions of high and low porosity could be used to control water removal, where the porosity difference has to be at least 0.1. The findings are consistent with recent studies of morphologically modified GDLs where milled or laser-perforated holes and lines serve as water-transport pathways [24][25][26][27][28][29], although these modifications were~100 μm, much larger than they needed to be based on the current study. However, evaporation/condensation due to thermal gradients and convection along the channel are not captured here but can have a significant impact on water distribution as in-operando studies for uncompressed GDLs have shown [30,31].…”

Section: Tomography Of Compressed Gdls With Water Intrusionsupporting

confidence: 92%

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Probing water distribution in compressed fuel-cell gas-diffusion layers using X-ray computed tomography

Zenyuk

Parkinson

Hwang

et al. 2015

Electrochemistry Communications

155

122

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X-ray computed tomography was used to investigate geometrical land and channel effects on spatial liquidwater distribution in gas-diffusion layers (GDLs) of polymer-electrolyte fuel cells under different levels of compression. At low compression, a uniform liquid-water front was observed due to water redistribution and uniform porosity; however, at high compression, the water predominantly advanced at locations under the channel for higher liquid pressures. At low compression, no apparent correlation between the spatial liquid water and porosity distributions was observed, whereas at high compression, a strong correlation was shown, indicating a potential for smart GDL architecture design with modulated porosity.

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Section: Tomography Of Compressed Gdls With Water Intrusionsupporting

confidence: 92%

“…Image reconstruction was done with commercial software Fiji and Octopus 8.5 [19]. The imaged data Electrochemistry Communications 53 (2015) [24][25][26][27][28] was of a high quality and minimal filtering was necessary for accurate segmentation. Table 1.…”

Section: Methodsmentioning

confidence: 99%

Probing water distribution in compressed fuel-cell gas-diffusion layers using X-ray computed tomography

Zenyuk

Parkinson

Hwang

et al. 2015

Electrochemistry Communications

155

122

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“…17 for 300-μm w/HAZ DM, especially as current increases. Markötter et al 43 recently concluded using a high-resolution X-ray synchrotron that the perforations indeed act as preferential liquid water pathways, drawing water from surrounding The additional liquid water storage and the redistribution of liquid water in both the in-and through-plane directions confirm the conclusion ascertained from the EIS results. Namely, two mechanisms lead to enhanced performance of the 100-μm w/HAZ DM: i) liquid water storage and interfacial through-plane redistribution rehydrate the CL and membrane, and ii) in-plane liquid water redistribution allow for increased oxygen transport to the reaction sites.…”

Section: Resultssupporting

confidence: 61%

Laser Perforated Fuel Cell Diffusion Media: Engineered Interfaces for Improved Ionic and Oxygen Transport

Manahan

Mench

2012

J. Electrochem. Soc.

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The purpose of this work is to explore engineered interfacial and structural architecture in fuel cell diffusion media (DM). Perforations were introduced via lasers on samples of virgin DM that contained hydrophobic content. Depending on laser choice, some lasercut samples displayed a "heat affected zone" (HAZ) at the catalyst layer | microporous layer interface, characterized by a region surrounding each perforation where hydrophobic content was removed. At 50% inlet relative humidity, DM with homogeneously dispersed 100-μm perforations and a HAZ displayed a 25% power density increase compared to virgin DM. Analyzing the oxygen concentration dependence in the double-Tafel region showed transport resistances were dominated by oxygen at moderate current values. Electrochemical impedance spectroscopy (EIS) and neutron radiography results indicated charge-and mass-transport impedances and liquid water redistribution play an important role, depending on the operating current density. Results suggested two mechanisms for the increased performance of the 100-μm DM with HAZ: i) liquid water storage and through-plane water redistribution led to rehydration of the catalyst layer and membrane, and ii) in-plane water redistribution led to improved oxygen transport through the DM. The results of this study shed light on the importance of interfacial and structural architecture of fuel cell DM.

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“…[26][27][28][29] There is an ongoing effort to optimize the porous macro-DM and MPL to boost performance. Groups are attempting laser modifications, [13][14][15][30][31][32][33] layer additions, [34][35][36] metallic DM, 37 and metallic foam. [38][39][40] Previously, Manahan et al [13][14][15] have shown that laserinduced perforations can be beneficial to PEFC performance, noting a 25% increase in peak power density when 50% inlet relative humidity (RH) gas streams are used with 100 μm perforations that have a locally-hydrophilic heat affected zone (HAZ).…”

mentioning

confidence: 99%

Laser Modified Fuel Cell Diffusion Media: Engineering Enhanced Performance via Localized Water Redistribution

Manahan¹,

Clement²,

Srouji³

et al. 2014

J. Electrochem. Soc.

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The present work demonstrates an innovative concept of obtaining enhanced performance via laser treatment of the cathode-side diffusion medium (DM) while mitigating identified degradation modes. A diffusion medium was modified such that hydrophilic heat affected zones (HAZ) were introduced, which led to localized water redistribution. However, no perforation was created, thus mitigating accelerated degradation of the catalyst layer and diffusion medium. This material was compared to a diffusion medium with 100-μm diameter perforations that contained heat affected zones surrounding the perforations. In-situ net water drag experiments indicate that at low humidity and low-to-moderate current densities, a non-perforated microporous layer (MPL) forces more water to back diffuse from the cathode to the anode. However, when more water is produced at higher currents or the inlet streams are close to saturation, the non-perforated MPL acts as a barrier to prevent liquid water in the cathode DM from moving toward the anode. Furthermore, a computational model showed that the thermal gradients introduced as a result of the perforations can significantly change the water transport, particularly due to phase-change induced flow. This work adds understanding to the role of the MPL and the laser-induced heat affected zones in polymer electrolyte fuel cell performance.

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Visualization of the water distribution in perforated gas diffusion layers by means of synchrotron X-ray radiography

Cited by 92 publications

References 19 publications

Probing water distribution in compressed fuel-cell gas-diffusion layers using X-ray computed tomography

Probing water distribution in compressed fuel-cell gas-diffusion layers using X-ray computed tomography

Laser Perforated Fuel Cell Diffusion Media: Engineered Interfaces for Improved Ionic and Oxygen Transport

Laser Modified Fuel Cell Diffusion Media: Engineering Enhanced Performance via Localized Water Redistribution

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