Structural and Physical Properties of GDL and GDL/BPP Combinations and their Influence on PEMFC Performance

Wilde, Peter; Mändle, M.; Murata, Makoto; Berg, N. A.

doi:10.1002/fuce.200400022

Cited by 115 publications

(67 citation statements)

References 3 publications

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“…[81][82][83][84] In addition, compression and landchannel effects can have similar effects on transport parameters. 37,[85][86][87][88][89][90][91][92] Locations of GDLs under land are more compressed, thus having lower porosity and hence lower permeability. To explore the impact of permeability, the anode liquid saturated permeability was decreased by factors between 10 and 100, and increased by factors 10 and 100 with the results as shown in Figure 7 and Figure 9a.…”

Section: Impact Of Catalyst-layer Thickness-as Shown Inmentioning

confidence: 99%

Understanding Impacts of Catalyst-Layer Thickness on Fuel-Cell Performance via Mathematical Modeling

Zenyuk

Das

Weber

2016

J. Electrochem. Soc.

144

136

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In this article, a two-dimensional, multiphase, transient model is introduced and used to explore the impact of catalyst-layer thickness on performance. In particular, the tradeoffs between water production and removal through transport or evaporation are highlighted, with a focus on low-temperature performance. For the latter, a case study of an ultra-thin catalyst layer is undergone to explore how various material properties alter the steady-state and startup performance of a cell. The findings provide understanding and guidance to optimize fuel-cell performance with thin electrodes. Polymer-electrolyte fuel cells (PEFCs) have emerged as a promising zero-emission technology for energy conversion due to their thermodynamic efficiency and high energy density.1,2 However, to reduce cost, the amount of precious metal catalyst needs to be lowered. The most common strategy for such catalyst thrifting is to fabricate thinner catalyst layers. The prototypical example of this approach is the nanostructured thin-film (NSTF) electrode, which has several advantages compared to standard carbon-supported Pt electrodes.2 These stateof-the art electrodes have demonstrated improved chemical stability, durability and desired specific power and activity, at the same time having high Pt mass activities. 2,3 Common to these and other lowloaded electrodes are the issues associated with water management in thinner electrodes. Typically, thinner electrodes are susceptible to severe flooding due to their inherently low water capacity and perhaps lack of hydrophobic zones. Such phenomena are particularly pronounced when PEFCs operate at lower temperatures or during startup.Recently, several studies reported water-management mitigation strategies for thinner electrodes including modification of operating conditions and/or component morphologies to ensure successful startup and operation at low temperatures. For example, for NSTF electrodes, Steinbach et al.4,5 reported a novel water-management scheme of increasing the pressure on the cathode to drive water to the anode; coupled with a different anode design, the limiting current density at low temperatures increased by a factor of four. Kongkanand et al. 6,7 demonstrated that water removal and storage capacity of the NSTF electrode can be significantly enhanced by placing an additional Pt/C layer between the electrode and microporous layer. The various empirical findings of NSTF as well as traditional supported thin electrodes 8 can be much better understood by examining the various tradeoffs engendered and complications arising from the use of thin catalyst layers.Currently, the transport mechanisms of water removal behind possible mitigation strategies for thin electrodes are not well understood. In terms of modeling, both pore-scale and continuum models have been generated, although only the latter are germane to understanding cell water and thermal management. 9 Examples of continuum models include bilayer models, such as the one developed by Sinha et al. 10 with a membrane and wat...

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Section: Impact Of Catalyst-layer Thickness-as Shown Inmentioning

confidence: 99%

Understanding Impacts of Catalyst-Layer Thickness on Fuel-Cell Performance via Mathematical Modeling

Zenyuk

Das

Weber

2016

J. Electrochem. Soc.

144

136

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“…Rolls of Sigracet® Gas Diffusion Layers GDL (carbon paper grades 24 AA, 25 AA), SGL Technologies GmbH, Meitingen, Germany) were treated with aqueous polytetrafluoroethylene (PTFE) dispersion by means of a dipping process in order to obtain a 5% (w/w) PTFE load of the substrates [22]. The hydrophobised substrates (designated as 24 BA and 25 BA) had open porosities of 89% (25 BA, 35 BA) and 84% (24 BA, 34 BA).…”

Section: Gdl Substratesmentioning

confidence: 99%

“…The GDLs were characterised with regard to electrical properties, porosity, gas permeability, water vapour transmission and liquid permeability [22,23]. Capillary flow porometry (CFP) was performed with a PMI capillar flow porometer (Porous Materials Inc, USA) and liquid permeability was carried out by means of a PMI liquid permability tester (Porous Materials Inc, USA).…”

Section: Characterizationmentioning

confidence: 99%

Mitigation of Water Management in PEM Fuel Cell Cathodes by Hydrophilic Wicking Microporous Layers

2010

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This study introduces a novel strategy for enhancing the performance of Polymer Electrolyte Fuel Cells at high current densities by means of an advanced gas diffusion layer design. The incorporation of hydrophilic wicking agents into microporous layers of the cathode gas diffusion layer improves water management, thus increasing the maximum power density of Polymer Electrolyte Fuel Cells. Ex-situ measurements with respect to water and vapour transport, and electrochemical polarisation data provide evidence suggesting that the beneficial effect has to be attributed to enhanced liquid water removal through the microporous layer.

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“…The GDL and CL in general have highly porous structure because of the requirements set by their functions [24], and the pores of GDL are crushed to some extent when compression pressure is applied. Generally speaking, increasing compression improves the electric conductivity of GDL [25,26] and decreases the contact resistance at the interfaces [27][28][29][30]. Furthermore, the preferential pathway for liquid water transport may be created in the compressed part of the GDL [31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Thermal Conductivity and Contact Resistance of Compressed Gas Diffusion Layer of PEM Fuel Cell

Nitta¹,

Himanen

Mikkola³

2008

Fuel Cells

103

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Faculty DepartmentAuthor ( This paper discusses the effect of compression pressure on the mechanical and thermal properties of gas diffusion layers (GDL).The stress-strain curve of the GDL revealed one nonlinear and two piecewise linear regions within the compression pressure range of 0 to 5.5 MPa. The thermal conductivity of the compressed GDL was found to be independent of the compression pressure and was determined to be 1.18 ± 0.11 W m-1 K-1. The thermal contact resistance between the GDL and graphite was evaluated by augmenting experiments with computer modeling. The thermal contact resistance decreased nonlinearly with increasing compression pressure. According to results here, the thermal bulk resistance of the GDL is comparable to the thermal contact resistance between the GDL and graphite. A simple one dimensional model predicted a temperature drop of 1.7-4.4 ˚C across the GDL and catalyst layer depending on compression pressures.

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Structural and Physical Properties of GDL and GDL/BPP Combinations and their Influence on PEMFC Performance

Cited by 115 publications

References 3 publications

Understanding Impacts of Catalyst-Layer Thickness on Fuel-Cell Performance via Mathematical Modeling

Understanding Impacts of Catalyst-Layer Thickness on Fuel-Cell Performance via Mathematical Modeling

Mitigation of Water Management in PEM Fuel Cell Cathodes by Hydrophilic Wicking Microporous Layers

Thermal Conductivity and Contact Resistance of Compressed Gas Diffusion Layer of PEM Fuel Cell

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