Effect of gas diffusion layer properties on the time of breakthrough

Shahraeeni, Mehdi; Hoorfar, Mina

doi:10.1016/j.jpowsour.2011.02.089

Cited by 10 publications

(5 citation statements)

References 20 publications

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“…These established saturation thresholds were attributed to the establishment of liquid water transport pathways that become static once breakthrough was reached. 102,103 This upper threshold in saturation was established at lower operating current densities in the degraded SGL 29 BC GDL compared to that in the pristine SGL 29 BC GDL. The establishment of this upper threshold at lower current density operation was attributed to the loss of GDL hydrophobicity via the degradation process, which is in strong agreement with previous works.…”

Section: Eis Analysis-figurementioning

confidence: 89%

“…94 With increasing through-plane position (starting at the local maximum saturation location, x = 84.5 μm), the water saturation first decreased with increasing through-plane distance, and this trend was attributed to the porosity gradient variation (specifically decreasing porosity with increasing through-plane position) and the establishment of a liquid water transport pathway (which, once established, provides the preferential pathway for liquid water transport). 102,103 Approximately mid-way through the carbon fiber substrate, the water saturation increased with increasing throughplane distance, and this trend was attributed to the porosity variation (specifically increasing porosity with increasing through-plane position) combined with the accumulation of liquid due to condensation driven by the cooling effects of the flow field. Compared to the GDLs without an MPL, the addition of the MPL significantly reduces the saturation level within the GDL.…”

Section: Eis Analysis-figurementioning

confidence: 99%

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Microporous Layer Degradation in Polymer Electrolyte Membrane Fuel Cells

Hang

George

Gao

et al. 2018

J. Electrochem. Soc.

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In this work, microporous layer (MPL) degradation was investigated through the characterization of polymer electrolyte membrane (PEM) fuel cell performance and in situ liquid water visualizations. While both the MPL and carbon fiber substrate underwent ex situ carbon corrosion-based degradation, the degradation of the MPL has the most significant impact on the electrochemical performance and the liquid water distribution within the operating PEM fuel cell. Specifically, MPL degradation resulted in larger quantities of liquid water accumulation within the gas diffusion layer (GDL), and we attributed this accumulation to the loss of MPL hydrophobicity caused by the carbon corrosion-based degradation process. The increased liquid water accumulation led to increased mass transport resistances and performance losses at high operating current densities (> 1.5 A/cm 2 ). With increasing current density, the liquid water saturation profile converged to an upper threshold within GDLs with MPLs, whereas an upper liquid water saturation threshold was not observed for GDLs without MPLs. Predictions of long-term performance characteristics of PEM fuel cells should be informed by the proneness of the MPL to carbon corrosion degradation.

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Section: Eis Analysis-figurementioning

confidence: 89%

Section: Eis Analysis-figurementioning

confidence: 99%

Microporous Layer Degradation in Polymer Electrolyte Membrane Fuel Cells

Hang

George

Gao

et al. 2018

J. Electrochem. Soc.

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“…The observed convergence to a final water profile pattern in the GDL is attributed to the establishment of distinct liquid water pathways, also known as the capillary dominated breakthrough pattern. 107,108 The upper thresholds of saturation patterns were established following liquid water breakthrough in the MPL and carbon fiber substrate regions. The terminal (upper) threshold saturation pattern was established in the aged GDLs at lower current densities compared to those of the pristine GDLs, and this earlier establishment of a breakthrough pattern may be explained by the loss of hydrophobicity in aged GDLs.…”

Section: Resultsmentioning

confidence: 99%

Accelerated Degradation of Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers

Liu

George

Banerjee

et al. 2017

J. Electrochem. Soc.

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In this work, as-received pristine GDLs were degraded (aged) through an accelerated ageing process by immersion into a 35% wt. solution of H 2 O 2 at 90 • C for 12 hours. Pristine and degraded GDLs were assembled in custom-built fuel cells for in operando synchrotron X-ray visualization. Electrochemical impedance spectroscopy (EIS) measurements were obtained, while synchrotron X-ray radiography was performed to investigate the effect of ageing on liquid water transport behavior. In both pristine and aged GDLs, the liquid water profile converged to an upper (terminal) threshold in the saturation pattern as the current density increased. The terminal steady state liquid water profile was established at a lower current density for the aged GDLs compared to that of the pristine GDLs. Higher water quantities of liquid water accumulated at the GDL/flow field channel and MPL/carbon fiber substrate interfaces of the fuel cell with an aged GDL compared to the fuel cell with a pristine GDL. The aged GDLs exhibited more liquid water accumulation at lower current densities. Increases in liquid water accumulation and reduced performance were attributed to the reduction in hydrophobicity of the GDL.

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“…Future work will involve exploring hydraulic admittances of simple interconnected pores in transparent materials to better understand the spectra observed in actual GDL materials as well as correlation of the observed spectra with simple visualization techniques [44].…”

Section: Discussionmentioning

confidence: 99%