Influence of cracks in the microporous layer on the water distribution in a PEM fuel cell investigated by synchrotron radiography

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

doi:10.1016/j.elecom.2013.04.006

Cited by 104 publications

(79 citation statements)

References 24 publications

(23 reference statements)

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“…If cracks develop in such a MPL and their apertures are in the range of 4.4 microns to 32 microns, the capillary pressure of these cracks will be in the range of 1.5kPa to10kPa. These are lower than the pressure in a working cell, and are much easier for liquid water to move through, consistent with the experiments [33,34]. Even for the super-hydrophobic MPL with a water contact angle of 150 o [39], if similar cracks develop within it, their capillary pressure is also much lower than the pressure of an working cell.…”

Section: Pore-size Distribution and Water Invasionsupporting

confidence: 67%

“…Therefore, there must be other pathways for the liquid water to exit. One possibility is cracks that might have developed in their MPL [33][34][35][36]. Although Aoyama et al [24] hypothesized that the water could have entered the MPL as water vapour, there must also be an exit for the liquid water condensed in the CL.…”

Section: Pore-size Distribution and Water Invasionmentioning

confidence: 99%

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Modelling water intrusion and oxygen diffusion in a reconstructed microporous layer of PEM fuel cells

Zhang

Gao

Ostadi

et al. 2014

International Journal of Hydrogen Energy

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The hydrophobic microporous layer (MPL) in PEM fuel cell improves water management but reduces oxygen transport. We investigate these conflict impacts using nanotomography and porescale modelling. The binary image of a MPL is acquired using FIB/SEM tomography. The water produced at the cathode is assumed to condense in the catalyst layer (CL), and then builds up a pressure before moving into the MPL. Water distribution in the MPL is calculated from its pore geometry, and oxygen transport through it is simulated using pore-scale models considering both bulk and Knudsen diffusions. The simulated oxygen concentration and flux at all voxels are volumetrically averaged to calculate the effective diffusion coefficients. For water flow, we found that when the MPL is too hydrophobic, water is unable to move through it and must find alternative exits. For oxygen diffusion, we found that the interaction of the bulk and Knudsen diffusions at pore scale creates an extra resistance after the volumetric average, and that the conventional dusty model substantially overestimates the effective diffusion coefficient.

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Section: Pore-size Distribution and Water Invasionsupporting

confidence: 67%

Section: Pore-size Distribution and Water Invasionmentioning

confidence: 99%

Modelling water intrusion and oxygen diffusion in a reconstructed microporous layer of PEM fuel cells

Zhang

Gao

Ostadi

et al. 2014

International Journal of Hydrogen Energy

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“…Synchrotron X-ray radiography offers high spatial and temporal resolutions (less than 10 μm and less than 10 s, respectively) [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57]. Though X-ray photons are not as sensitive as a neutron beam to the presence of liquid water, Chevalier et al [29] demonstrated that synchrotron X-ray radiography can achieve similar accuracy to neutron radiography with a high level of precision.…”

Section: Visualizations Of Liquid Water Saturationmentioning

confidence: 99%

Liquid water saturation and oxygen transport resistance in polymer electrolyte membrane fuel cell gas diffusion layers

Muirhead

Banerjee

George

et al. 2018

Electrochimica Acta

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In this thesis, the relative humidity (RH) of the cathode reactant gas was investigated as a factor which influences gas diffusion layer (GDL) liquid water accumulation and mass transport-related efficiency losses over a range of operating current densities in a polymer electrolyte membrane (PEM) fuel cell. Limiting current measurements were used to characterize fuel cell oxygen transport resistance while simultaneous measurements of liquid water accumulation were conducted using synchrotron X-ray radiography. GDL porosity distributions were characterized with micro-computed tomography (μCT). The work presented here can be used by researchers to develop improved numerical models to predict GDL liquid water accumulation and to inform the design of next-generation GDL materials to mitigate mass transport-related efficiency losses. This work also contributes an extensive set of concurrent performance and liquid water visualization data to the PEM fuel cell field that can be used for validating multiphase transport models.iii

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“…[13][14][15][16][17][18] There exist several X-ray imaging studies, which describe the liquid water transport through perforations and cracks. 14,[19][20][21] Fuel cell tests of these types of materials have shown that specifically engineered large pores in the MPL/GDL-S can enhance the overall fuel cell performance, increase the limiting current density and accordingly reduce the oxygen transport resistance. 16,18,22 [1] where γ H 2 O is the surface tension of water, θ is the inner contact angle of water with the pore surface, d pore is the pore diameter, and p c is the capillary pressure describing the difference between the liquid pressure (p L ) and the corresponding vapor phase pressure (p V ).…”

mentioning

confidence: 99%

Impact of Microporous Layer Pore Properties on Liquid Water Transport in PEM Fuel Cells: Carbon Black Type and Perforation

Simon

Kartouzian

Müller

et al. 2017

J. Electrochem. Soc.

110

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The oxygen and water transport through various microporous layers (MPLs) is investigated by fuel cell tests in a 5 cm 2 active area cell under differential-flow conditions, analyzing polarization curves, the associated high-frequency resistance, and the oxygen transport resistance extracted from limiting current density measurements. In this study, MPLs with two different carbon blacks are prepared and compared to a commercial material, all coated on the same GDL-substrate (Freudenberg); furthermore, perforated MPLs with large pores produced by a thermally decomposable polymeric pore former with a particle diameter of ≈30 μm are examined. The materials are characterized by mercury porosimetry, nitrogen adsorption and scanning electron microscopy. While at dry conditions (T cell = 80 • C, RH = 70%, p abs = 170 kPa) the performance of all materials is similar, at conditions of high water saturation (T cell = 50 • C, RH = 120%, p abs = 300 kPa), MPLs with larger pores or perforations exhibit a performance improvement due to a ≈30% reduction in oxygen transport resistance. The results indicate that liquid water is transported exclusively through these large pores, while the oxygen transport occurs in the small pores defined by the carbon black structure.

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Influence of cracks in the microporous layer on the water distribution in a PEM fuel cell investigated by synchrotron radiography

Cited by 104 publications

References 24 publications

Modelling water intrusion and oxygen diffusion in a reconstructed microporous layer of PEM fuel cells

Modelling water intrusion and oxygen diffusion in a reconstructed microporous layer of PEM fuel cells

Liquid water saturation and oxygen transport resistance in polymer electrolyte membrane fuel cell gas diffusion layers

Impact of Microporous Layer Pore Properties on Liquid Water Transport in PEM Fuel Cells: Carbon Black Type and Perforation

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