Neutron Radiographic Investigations on the Effect of Hydrophobicity Gradients within MPL and MEA on Liquid Water Distribution and Transport in PEMFCs

Mohseninia, Arezou; Kartouzian, Dena; Markötter, Henning; Ince, Utku U.; Manke, Ingo; Scholta, Joachim

doi:10.1149/08513.1013ecst

Cited by 6 publications

(9 citation statements)

References 22 publications

(23 reference statements)

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“…Lee et al 18 observed the water transport with X-ray radiography and found that MPL improves the performance and reliability of the fuel cell and prevents the flooding. Mohseninia et al 19 studied the effect of MPL on water transport with neutron radiography and further proved that the MPL could cause water back diffusion from the cathode to the anode side. Similar conclusion was also drawn by Kim et al 20 that MPL can decrease the mass transport resistance and maintain a high water-content in the membrane even in low anode humidification condition by back diffusion.…”

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confidence: 99%

Pore-Scale Investigation of the Effect of Micro-Porous Layer on Water Transport in Proton Exchange Membrane Fuel Cell

Hou

et al. 2020

J. Electrochem. Soc.

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A 3D lattice Boltzmann model is developed to simulate the pore-scale two-phase flow in the porous transport layer (PTL). The PTL, composed of the gas diffusion layer (GDL) and the micro porous layer (MPL), is stochastically reconstructed and validated by comparing the pore size distribution (PSD) with experimental data. This work focuses on the effect of MPL on liquid water transport in terms of hydrophobicity, PSD and structure. It is found that more hydrophobic material and smaller pore size apply higher local capillary force against the water transport. Water can only break through the crack-free MPL under an extremely high inlet pressure (about 400 kPa). Under the real operating conditions of a fuel cell, the PTL with single GDL suffers flooding with a low fraction of dry pore. With the presence of cracked MPL, the fraction of dry pore increases significantly since a large amount of water is constrained in the electrode and only the rest flows into the GDL through the cracks, which can keep the membrane hydrated and avoid flooding. Finally, a systematically designed PTL is proposed with uniformly distributed perforations, which can automatically balance the water content and further optimize the proton conductivity and reactant transport, simultaneously.

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confidence: 99%

Pore-Scale Investigation of the Effect of Micro-Porous Layer on Water Transport in Proton Exchange Membrane Fuel Cell

Hou

et al. 2020

J. Electrochem. Soc.

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“…In addition to the hydrophobic MPL acting as a barrier against the transfer of water to the cathode side, one can also hypothesize that under the channels the reaction rates are higher and cathode catalyst layer is at a higher temperature than anode CL; therefore, phase‐change‐induced flow shifts the water peak towards the anode. This result is also compatible with our previous neutron radiographic studies on the behavior of water dynamics of cells with hydrophobic MEA and MPL components where the hydrophobized MPL on cathode side decreased the transfer of water to the cathode channels, and subsequently has imposed the water to the opposite side .…”

Section: Resultsmentioning

confidence: 99%

“…SEM images of the home-made perforated MPLs and the commercial 29 BC (MPL and substrate side) are depicted in Figures 3 and 4, respectively. A more detailed description of the fabrication processes of the reference CL and MPL was presented in previous articles [21,47,48]. The components of the cells containing the perforated layers are listed in Table 2.…”

Section: Materials Preparationmentioning

confidence: 99%

“…The latter observation gives some hint for the potential of further improvements of such MPL designs. In a previous study, we examined that optimum hydrophobization of catalyst layers with 5 wt.% PTFE enhanced the performance of the cell at dry conditions (for all current ranges) and at humid conditions (for low and medium current densities) [47]. A detailed tomography study on the effect of hydrophobicity gradients within fuel cell components was also presented in our previous work [48].…”

Section: Influence Of Hydrophobicity Variation On Water Content and Cmentioning

confidence: 99%

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Influence of Structural Modification of Micro‐Porous Layer and Catalyst Layer on Performance and Water Management of PEM Fuel Cells: Hydrophobicity and Porosity

et al. 2020

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The influence of hydrophobicity and porosity of the catalyst layer (CL) and cathode microporous layer (MPLC) on water distribution and performance of polymer electrolyte membrane fuel cell (PEMFC) is investigated. Hydrophobicity of the layers is altered with the addition of PTFE (polytetrafluoroethylene) and mono‐dispersed polymer particles are utilized to introduce the macro‐pores with a diameter of 0.5 µm and 30 µm within the CL and MPLC, respectively. The treated materials are implemented in a specially designed fuel cell with an active area of 8 cm2 to perform operando high‐resolution neutron tomography measurements. At high current density and humid operating conditions, MPLs with higher PTFE content increase the overall water content of the cell. The more hydrophobic MPL (40 wt.% PTFE) performs below the corresponding reference MPL (20 wt.% PTFE), whereas the performance result of double layer MPLC gives hint for further potential improvements of such design. The local water saturation beneath the land regions with the presence of perforated CL and MPLC is increased which is explained by lower capillary pressure barriers of bigger pores. Despite a higher water content, the perforated layers enhance the performance of the cell at both dry (RH 70%) and humid conditions (RH 120%), indicating that the parallel two‐phase flow is facilitated where the oxygen is transported through small pores and the water is preferentially transported through the bigger pores.

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“…Neutron imaging has been used as a state‐of‐the‐art technique for visualizing liquid water in operating PEMFCs with a high special resolution . Several groups have successfully employed neutron tomography to advance the understanding of the relationship between liquid water behavior and the complex structural heterogeneity of porous media …”

Section: Components Of the Cellmentioning

confidence: 99%

Enhanced Water Management in PEMFCs: Perforated Catalyst Layer and Microporous Layers

et al. 2020

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An experimental in situ study wasp erformed to investigate the effects of the catalystl ayer (CL) and cathode microporous layer (MPL c )p erforation on the water management and performance of polymer electrolyte membrane fuel cells (PEMFCs). Polymeric pore formers were utilized to produce perforated CL and MPL structures. High-resolutionn eutron tomography was employedt ovisualize the liquid water contentand distribution within differentc omponents of the cell under channel and land regions.T he results revealed that at humid conditions, the perforated layers enhanced the liquid water transport under the channel regions. Moreover, at high current densities, the performance was improved for the cells with perforated layers compared to ab aseline cell with non-perforated layers, owing to reduced mass transport losses.

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Neutron Radiographic Investigations on the Effect of Hydrophobicity Gradients within MPL and MEA on Liquid Water Distribution and Transport in PEMFCs

Cited by 6 publications

References 22 publications

Pore-Scale Investigation of the Effect of Micro-Porous Layer on Water Transport in Proton Exchange Membrane Fuel Cell

Pore-Scale Investigation of the Effect of Micro-Porous Layer on Water Transport in Proton Exchange Membrane Fuel Cell

Influence of Structural Modification of Micro‐Porous Layer and Catalyst Layer on Performance and Water Management of PEM Fuel Cells: Hydrophobicity and Porosity

Enhanced Water Management in PEMFCs: Perforated Catalyst Layer and Microporous Layers

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