Physical degradation of membrane electrode assemblies undergoing freeze/thaw cycling: Diffusion media effects

Kim, Soohwan; Ahn, Byung Ki; Mench, Matthew M.

doi:10.1016/j.jpowsour.2007.12.114

Cited by 141 publications

(85 citation statements)

References 12 publications

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“…For example, Kim et al [92] reported interfacial delamination between the CL and GDL after 100 freeze/thaw cycles from −40 • C to 70 • C, which resulted from ice formation and in turn significantly increased GDL deformation. Mukundan et al [93] conducted freeze/thaw cycles down to −80 • C using dry ice, and their results indicated that multiple cycles could lead to interfacial delamination and GDL failure in the fuel cell.…”

Section: Cellmentioning

confidence: 99%

A review of polymer electrolyte membrane fuel cell durability test protocols

Yuan

Zhang

et al. 2011

Journal of Power Sources

298

121

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a b s t r a c tDurability is one of the major barriers to polymer electrolyte membrane fuel cells (PEMFCs) being accepted as a commercially viable product. It is therefore important to understand their degradation phenomena and analyze degradation mechanisms from the component level to the cell and stack level so that novel component materials can be developed and novel designs for cells/stacks can be achieved to mitigate insufficient fuel cell durability. It is generally impractical and costly to operate a fuel cell under its normal conditions for several thousand hours, so accelerated test methods are preferred to facilitate rapid learning about key durability issues. Based on the US Department of Energy (DOE) and US Fuel Cell Council (USFCC) accelerated test protocols, as well as degradation tests performed by researchers and published in the literature, we review degradation test protocols at both component and cell/stack levels (driving cycles), aiming to gather the available information on accelerated test methods and degradation test protocols for PEMFCs, and thereby provide practitioners with a useful toolbox to study durability issues. These protocols help prevent the prolonged test periods and high costs associated with real lifetime tests, assess the performance and durability of PEMFC components, and ensure that the generated data can be compared.Crown

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Section: Cellmentioning

confidence: 99%

A review of polymer electrolyte membrane fuel cell durability test protocols

Yuan

Zhang

et al. 2011

Journal of Power Sources

298

121

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“…The origin of these profiles is due to the complex nature of both the material heterogeneities as well as phenomena such as phase-change-induced (PCI) flow where water moves due to phase transitions. For example, water evaporating and condensing along a temperature gradient can have a large impact on the cell performance [51][52][53][54][55][56][57][58][59], or similarly, during shutdown in a cold-environment, water is predicted and shown to move due to freezing [60][61][62]. Thus, a valuable and predictive macroscopic model must be able to handle changes in the chemical and physical DM structure along with the various dominant transport phenomena.…”

Section: Introductionmentioning

confidence: 99%

Improved modeling and understanding of diffusion-media wettability on polymer-electrolyte-fuel-cell performance

Weber¹

2010

Journal of Power Sources

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A macroscopic-modeling methodology to account for the chemical and structural properties of fuel-cell diffusion media is developed. A previous model is updated to include for the first time the use of experimentally measured capillary pressure -saturation relationships through the introduction of a Gaussian contact-angle distribution into the property equations. The updated model is used to simulate various limiting-case scenarios of water and gas transport in fuel-cell diffusion media. Analysis of these results demonstrate that interfacial conditions are more important than bulk transport in these layers, where the associated mass-transfer resistance is the result of higher capillary pressures at the boundaries and the steepness of the capillary pressuresaturation relationship. The model is also used to examine the impact of a microporous layer, showing that it dominates the response of the overall diffusion medium. In addition, its primary mass-transfer-related effect is suggested to be limiting the water-injection sites into the more porous gas-diffusion layer.

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“…31 Ionomer-catalyst ratio and CL thickness were key parameters affecting the ice holding capacity of MEAs before operational failure in freeze starts. 32 The physical structure of the GDL may be directly damaged by the formation of ice, 33 potentially altering the hydrophobicity of micropores. Oszcipok et al 3 reported an increase in surface wetting of both plate-and catalyst-side surfaces of a cathode GDL operated through 10 cold-start experiments from −10…”

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confidence: 99%

Durability of Polymer Electrolyte Membrane Fuel Cells Operated at Subfreezing Temperatures

Macauley

Lujan

Spernjak

et al. 2016

J. Electrochem. Soc.

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The structure, composition, and interfaces of membrane electrode assemblies (MEA) and gas-diffusion layers (GDLs) have a significant effect on the performance of single-proton-exchange-membrane (PEM) fuel cells operated isothermally at subfreezing temperatures. During isothermal constant-current operation at subfreezing temperatures, water forming at the cathode initially hydrates the membrane, then forms ice in the catalyst layer and/or GDL. This ice formation results in a gradual decay in voltage. High-frequency resistance initially decreases due to an increase in membrane water content and then increases over time as the contact resistance increases. The water/ice holding capacity of a fuel cell decreases with decreasing subfreezing temperature (−10 • C vs. −20 • C vs. −30 • C) and increasing current density (0.02 A cm −2 vs. 0.04 A cm −2 ). Ice formation monitored using in-situ highresolution neutron radiography indicated that the ice was concentrated near the cathode catalyst layer at low operating temperatures (≈−20 • C) and high current densities (0.04 A cm −2 ). Significant ice formation was also observed in the GDLs at higher subfreezing temperatures (≈−10 • C) and lower current densities (0.02 A cm −2 ). These results are in good agreement with the long-term durability observations that show more severe degradation at lower temperatures (−20 • C and −30 • C).

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Physical degradation of membrane electrode assemblies undergoing freeze/thaw cycling: Diffusion media effects

Cited by 141 publications

References 12 publications

A review of polymer electrolyte membrane fuel cell durability test protocols

A review of polymer electrolyte membrane fuel cell durability test protocols

Improved modeling and understanding of diffusion-media wettability on polymer-electrolyte-fuel-cell performance

Durability of Polymer Electrolyte Membrane Fuel Cells Operated at Subfreezing Temperatures

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