Perspective—Mesoscale Physics in the Catalyst Layer of Proton Exchange Membrane Fuel Cells

Grunewald, Jonathan B.; Mistry, Aashutosh; Verma, Ankit; Goswami, Navneet; Mukherjee, Partha P.; Fuller, Thomas F.

doi:10.1149/2.0111907jes

Cited by 13 publications

(6 citation statements)

References 64 publications

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“…Since recent improvements in visualization techniques and Lattice Boltzmann Methods offer new opportunities to directly simulate the dynamics of water movement in the CCL using the actual geometry of the catalyst layer, understanding how these dynamics change with degradation requires the use of Young's contact angle rather than the apparent contact angle. 30 Thus, it is necessary to use a model to relate the two contact angles.…”

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confidence: 99%

Effect of Carbon Corrosion on Wettability of PEM Fuel Cell Electrodes

Fang

Star

Fuller

2019

J. Electrochem. Soc.

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Large transport resistances at high current densities hinder the proton-exchange-membrane fuel cells from reaching performancecost-durability targets. Extensive carbon corrosion in the cathode catalyst layers (CCL) has been shown to correlate to pore closures and increase in surface oxides of carbon support, which has been associated with the increase in wettability of CCLs. This study investigated effects of microstructure and surface oxides on the change of wetting properties of CCLs after different accelerated stress tests. The apparent contact angles were measured over a broad range of carbon mass losses at 0.3 mg Pt /cm 2 . The apparent contact angles fell sharply after small extent of carbon loss followed by a plateau, and decreased again after 123 μg/cm 2 (35% carbon support loss). The microstructural changes were characterized by surface roughness (atomic force microscopy) and porosity (focus-ion-beam scanning electron microscopy and thermogravimetric analysis). The surface roughness and porosity were used to parameterize Wenzel's, Cassie-Baxter's, and combined models to elucidate the changes in Young's contact angle. The fittings of the models revealed that the CCLs sustained their wettability after up to 35% of carbon support loss due to the increases in the proportion of hydrophobic fluorocarbon chains on the surface of the CCLs measured from XPS.

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confidence: 99%

Effect of Carbon Corrosion on Wettability of PEM Fuel Cell Electrodes

Fang

Star

Fuller

2019

J. Electrochem. Soc.

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“…Such studies delineated above not only highlight the interactions between the constituent phases but can also give fundamental insights into various intertwined aspects of catalyst ink preparation like mixing time, mixing sequence, dispersion solvents 26 that are responsible for a prudent design of the CCL microstructure. 27,28 With a view of catalyst layer optimization, several studies have been devoted to investigating the effect of ionomer content. [29][30][31][32] Of late, the distribution of the ionomer phase 33,34 has been a critical design parameter to better PEFC electrode performance.…”

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confidence: 99%

Corrosion-Induced Microstructural Variability Affects Transport-Kinetics Interaction in PEM Fuel Cell Catalyst Layers

Goswami

Mistry

Grunewald

et al. 2020

J. Electrochem. Soc.

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The ionomer, which is responsible for proton transport, oxygen accessibility to reaction sites, and binding the carbon support particles, plays a central role in dictating the catalyst layer performance. In this work, we study the effect of ionomer distribution owing to the corrosion induced degradation mode in the catalyst layer based on a combined mesoscale modeling and experimental image-based data. It is observed that the coverage of the ionomer over the platinum-carbon interface is heterogeneous at the pore-scale which in turn can critically affect the electrode-scale performance. Further, an investigation of the response of the pristine as well as degraded microstructures that have been exposed to carbon support corrosion has been demonstrated to highlight the kinetic-transport underpinnings on the catalyst layer performance decay.

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“…Experimental studies have been focused on in situ measuring of film transport resistivity using limiting current method [13][14][15][16][17]. The references above indicate just several exemplary works; more papers could be found in reviews [18][19][20].…”

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confidence: 99%

Oxygen transport in the low–Pt catalyst layer of a PEM fuel cell: Impedance spectroscopy study

Reshetenko

Kulikovsky

2023

Mater. Res. Express

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A model for PEM fuel cell impedance taking into account the pore size distribution (PSD) in the cathode catalyst layer is developed. Experimental PSD is approximated by pores of three sizes (small, medium, large) and in each kind of pores, the oxygen diffusion coefficient is allowed to have a separate value. The model is fitted to experimental impedance spectra of a low--Pt PEM fuel cell. The oxygen diffusivities of small and medium pores exhibit rapid growth with the cell current density, while in large pores, this parameter remains nearly constant. We show that oxygen reduction occurs mainly in the small and medium pores, leaving the large pores for mass transport only. This effect explains the discrepancy between small effective oxygen diffusivity of PEMFC catalyst layer measured in--situ in operating cells by limiting current method, and much larger value of this parameter determined from ex--situ experiments using Loschmidt cell.

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Perspective—Mesoscale Physics in the Catalyst Layer of Proton Exchange Membrane Fuel Cells

Cited by 13 publications

References 64 publications

Effect of Carbon Corrosion on Wettability of PEM Fuel Cell Electrodes

Effect of Carbon Corrosion on Wettability of PEM Fuel Cell Electrodes

Corrosion-Induced Microstructural Variability Affects Transport-Kinetics Interaction in PEM Fuel Cell Catalyst Layers

Oxygen transport in the low–Pt catalyst layer of a PEM fuel cell: Impedance spectroscopy study

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