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Jordan, Larry R.; Shukla, A. K.; Behrsing, Thomas; Avery, Neil R.; Muddle, Barry C.; Forsyth, Maria

doi:10.1023/a:1004088402496

Cited by 124 publications

(63 citation statements)

References 12 publications

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“…Figure 1 shows the TGA data and the applied temperature ramp mimicking the heat-treatment procedure during the preparation of GDLs and freestanding MPLs, which is necessary to decompose undesired components in the MPL, such as emulsifiers and thickeners, and to sinter PTFE particles, which improves the overall performance. 33,34 The dried PTFE dispersion consists of PTFE and emulsifier and is showing a weight loss of 7 wt% over the whole heat-treatment procedure, initiating at a temperature of ≈210…”

Section: Resultsmentioning

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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Section: Resultsmentioning

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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“…(17); and (iii) the region on the right (second sharp drop) corresponds to the concentration polarization, accounted for by the last two terms of Eq. (17). Note that, the polarization curves of the four porosity mod-els overlap in the region of low-to-medium current density (the linear regime), while at higher current density close to the limiting value, differences between the four models become significant.…”

Section: Physical Explanation Of Performance Modelmentioning

confidence: 90%

“…In fact, the GDL is composed of a thin layer of carbon black mixed with polytetrafluoroethylene (PTFE), a carbon paper consisting of rigid carbon fibbers with a diameter of about 10 m, and a porous structure formed by carbon fibbers with a pore size of 20-50 m and 70-80% porosity of volume. Any change in the composition or the morphology of the GDL can lead to a substantial influence on fuel cell performance owing to a porosity change [16][17][18][19]. In practice, the presence of water generated in the GDL during fuel cell operation can also change the effective porosity, and this change may vary with time and position.…”

Section: Introductionmentioning

confidence: 99%

Effects of porosity change of gas diffuser on performance of proton exchange membrane fuel cell

Chu

Yeh

Chen

2003

Journal of Power Sources

163

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An investigation is made of the effects of the change of the porosity of the gas diffuser layer (GDL) on the performance of a proton exchange membrane (PEM) fuel cell. The analysis of fuel cell performance with non-uniform porosity of GDL is a necessity because the presence of liquid water in the GDL leads to a non-uniformly distributed porosity in the GDL. To implement this performance analysis, a half-cell model which considers the oxygen mass fraction distribution in the gas channel, the GDL and the catalyst layer, and the current density and the membrane phase potential in the catalyst layer and the membrane is investigated. Four continuous functions of position are employed to describe the porosity, and differential equations are derived based on oxygen transportation and Ohm's law for proton migration and solved numerically. Results show that a fuel cell embedded with a GDL with a larger averaged porosity will consume a greater amount of oxygen, so that a higher current density is generated and a better fuel cell performance is obtained. This explains partly why fuel cell performance deteriorates significantly as the cathode is flooded with water (i.e. to give a lower effective porosity in the GDL). In terms of the system performance, a change in GDL porosity has virtually no influence on the level of polarization when the current density is medium or lower, but exerts a significant influence when the current density is high. This finding supports the scenario proposed by previous studies that the polarization at high current density corresponds mainly to mass transfer through (or the concentration activation of) the membrane assembly.

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“…Different experimental groups have shown that the use of MPLs usually results in FCs that exhibit better performance. [1][2][3][4][5][6][7][8][9][10][11] However, the improvement depends on the operating conditions, and the exact reasons are mainly unknown and unquantified.…”

mentioning

confidence: 99%

“…Flooding losses were less when the air was fed humidified, and with a dry air feed, the ohmic losses were lower as well. Jordan et al 8 examined the effect of the pore size distribution ͑PSD͒ of the MPLs on performance. They did this by examining different types of carbon.…”

mentioning

confidence: 99%

Effects of Microporous Layers in Polymer Electrolyte Fuel Cells

Weber

Newman

2005

J. Electrochem. Soc.

516

430

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Our previous models and a catalyst-layer model are combined to study the effects of microporous layers in polymer electrolyte fuel cells. The combined sandwich model is used to fit data both with and without a microporous layer with saturated feed conditions. In terms of water management, the simulations clearly show that the effect of a microporous layer is to keep water out of the cathode gas diffusion layer and move it through the anode. Additional effects of microporous layers include better ohmic behavior and perhaps better catalyst utilization, among other things. Optimizations for different structural parameters are investigated, as are the effects of microporous layers under different operating conditions. The discussion is geared toward how microporous layers increase performance and their effect on fuel cell water management. © 2005 The Electrochemical Society. ͓DOI: 10.1149/1.1861194͔ All rights reserved. In the ongoing search for better-performing fuel cells ͑FCs͒, different design approaches have been used. One such approach that is getting more attention is the use of a bilayer diffusion medium, made up of a hydrophobic-rich microporous layer ͑MPL͒ and a traditional gas diffusion layer ͑GDL͒, in which the MPL is next to the catalyst layer. Different experimental groups have shown that the use of MPLs usually results in FCs that exhibit better performance.1-11 However, the improvement depends on the operating conditions, and the exact reasons are mainly unknown and unquantified.In terms of experimental systems with MPLs, one of the first studies was done by Wilson et al., 1 who studied two different types of MPLs. They found that the one that was more hydrophobic and had larger pores was not as good as the other one, but that it did demonstrate better performance with subsaturated feeds. Hara et al. 2did a similar analysis with MPLs for phosphoric acid FCs. Janssen and Overvelde 3 examined the water balance in operating polymer electrolyte FCs with commercial membrane electrode assemblies with different MPL configurations. Their results showed increased performance with hydrophobic MPLs. For either humidified or dry feeds, the system with a net water flux per proton flux in the membrane closer to zero exhibited better performance. This is undoubtedly due to keeping the membrane hydrated while also reducing the amount of water moving through the cathode diffusion medium.Paganin et al. 4 examined MPLs in which the Teflon content and thickness of the MPLs was altered. Their results demonstrated improvement in the polarization characteristics that depended more on the thickness than on the Teflon percentage. Operation with pure oxygen clearly showed that the enhancement in performance was mainly due to decreased ohmic losses. Passalacqua et al.5 introduced an MPL and operated their system with both oxygen and air. They clearly showed that an MPL improved performance by reducing mass-transport limitations, especially with the air feed, and also by reducing ohmic losses, especially with the oxygen feed....

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Cited by 124 publications

References 12 publications

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

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

Effects of porosity change of gas diffuser on performance of proton exchange membrane fuel cell

Effects of Microporous Layers in Polymer Electrolyte Fuel Cells

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