Experimental Method to Determine the Mass Transport Resistance of a Polymer Electrolyte Fuel Cell

Beuscher, Uwe

doi:10.1149/1.2218760

Cited by 86 publications

(68 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In addition, this technique does not allow the assessment of properties such as effective diffusivity as a function of liquid saturation as one cannot readily control the latter. To overcome the above issues, researchers have opened up the parameter space by stacking DM [8], diluting the reactant gases in different carrier gases [4,8], and varying the cell pressure [9][10][11]. Researchers have also used various ex-situ techniques to characterize DM.…”

Section: Figure 1: Schematic Of Oxygen Diffusion Losses In a Fuel-celmentioning

confidence: 99%

Investigating fuel-cell transport limitations using hydrogen limiting current

Spingler

Phillips

Schuler

et al. 2017

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

Reducing mass-transport losses in polymer-electrolyte fuel cells (PEFCs) is essential to increase their power density and reduce overall stack cost. At the same time, cost also motivates the reduction in expensive precious-metal catalysts, which results in higher local transport losses in the catalyst layers. In this paper, we use a hydrogen-pump limitingcurrent setup to explore the gas-phase transport losses through PEFC catalyst layers and various gas-diffusion and microporous layers. It is shown that the effective diffusivity in the gas-diffusion layers is a strong function of liquid saturation. In addition, it is shown how the catalyst layer unexpectedly contributes significantly to the overall measured transport resistance. This is especially true at low catalyst loadings. It is also shown how the various losses can be separated into different mechanisms including diffusional processes and massdependent and independent ones, where the data suggests that a large part of the transport resistance in CLs cannot be attributed to a gas-phase diffusional process. The technique is promising for deconvoluting transport losses in PEFCs.2

show abstract

Section: Figure 1: Schematic Of Oxygen Diffusion Losses In a Fuel-celmentioning

confidence: 99%

Investigating fuel-cell transport limitations using hydrogen limiting current

Spingler

Phillips

Schuler

et al. 2017

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

show abstract

“…Adopting the single-phase transport model, 38,39 the local diffusive flux can be linearized through defining the mass transfer coefficient, k, which is defined as the ratio of overall diffusion coefficient over the diffusion path. 40 The mass transfer coefficient is of a great interest since it can be obtained from the experimental data of flux and the concentration difference ( C) even if the exact geometry or diffusion distance, is not known. The inverse of the mass transfer coefficient is defined as the mass transport resistance, R M .…”

Section: Pefc Configurations-the Different Combinations Of Mpls Usedmentioning

confidence: 99%

Water Management in Polymer Electrolyte Fuel Cells through Asymmetric Thermal and Mass Transport Engineering of the Micro-Porous Layers

Gandomi

Edmundson

Busby

et al. 2016

J. Electrochem. Soc.

View full text Add to dashboard Cite

For polymer electrolyte fuel cells (PEFCs) operating at very high current, prevention of anode dry-out through enhanced back flux of water and restriction of evaporation is required. In this work, back flux of water to the anode is engineered using an asymmetric anode and cathode micro-porous layer (MPL) configuration. Extensive experimental tests have been conducted to study the impact of thermal and mass transport resistances on the net water flux coefficient for extremes of wet and dry operating conditions. The net water drag coefficient was measured in the range of −0.17 to +0.18 depending on the operating conditions and material configurations. A simplified model has also been developed to investigate the effect of temperature gradient on the net water drag coefficient. It is shown that with an asymmetric configuration, the net flux of water can be reversed under certain conditions, greatly enhancing high current density performance. For wet operating conditions, the cell configuration with asymmetric mass transport resistance can be utilized to tailor the back flux of water. For dry operating conditions, the thermal resistance is the key controlling parameter to affect the net water drag. Water management remains an important topic in polymer electrolyte fuel cell (PEFC) systems. Water is required to keep the membrane hydrated to maintain ionic conductivity. However, excessive liquid-water accumulation in the gas flow channels and in the porous media (gas diffusion layer (GDL), and catalyst layers) limits reactants' transport to the electrocatalyst (a phenomenon called flooding). The membrane's transport properties are known to be a strong function of water content within the membrane. Extensive dry-out at the anode side and subsequent conductivity loss results in poor overall performance. Several passive and active approaches have been utilized for water management within the PEFCs (e.g. Refs. 1-6). A good review of these techniques has been provided in Ref. 7 and a recent review of water transport within PEFCs is discussed in Ref. 8. The micro-porous layer (MPL) at the electrodes have been used to improve the performance of PEFC via water management. Pasaogullari et al.9 modeled the two-phase transport in the porous layers of a PEFC cathode side. Their modeling results predicted that the existence of a MPL in the cathode side enhances liquid-water removal and reduces liquid saturation in the catalyst layer. Weber and Newman 10 explored the effects of MPL in terms of water management using a two-phase flow and membrane model. Their simulation predicted that the MPL acts as a valve that pushes water away from the GDL in the cathode side through the membrane and accordingly minimizes flooding. Yan et al.11 measured the net water flux transferred across the membrane under various operating conditions. They measured the net flux coefficients ranging from +0.93 to −0.2 depending on the current density and humidification of feed gases. R. Zaffou et al. 12 quantified the temperature-gradient-driven water tr...

show abstract

“…2,3 Over the past decade there have been numerous studies focusing on the optimization of the catalyst layer and seeking to gain fundamental insights into the various kinetic and transport resistances, which limit the performance of air cathodes, particularly at low Pt loadings. [4][5][6][7][8] While several methods were developed to quantify the voltage losses, there still remain unexplained voltage losses at high current density, particularly in the case of low Pt loading cathodes. [9][10][11][12][13][14] These have been rationalized by suggesting more complex oxygen reduction reaction (ORR) kinetics with variable Tafel slope, 4 by an interfacial resistance at the ionomer/platinum interface, 9,15 and/or by unusually high oxygen transport resistances through an assumed homogeneous thin ionomer film covering the Pt particles.…”

mentioning

confidence: 99%

The Key to High Performance Low Pt Loaded Electrodes

Orfanidi

Madkikar

El‐Sayed

et al. 2017

J. Electrochem. Soc.

215

252

View full text Add to dashboard Cite

The effect of ionomer distribution on the oxygen mass transport resistance, the proton resistivity of the cathode catalyst layer, and the H 2 /air fuel cell performance was investigated for catalysts with surface modified carbon supports. By introducing nitrogen containing surface groups, it was shown that the ionomer distribution in the cathodic electrode can be optimized to decrease mass transport related voltage losses at high current density. The in house prepared catalysts were fully characterized by TEM, TGA, elemental analysis, and XPS. Thin-film rotating disk electrode measurements showed that the carbon support modification did not affect the oxygen reduction activity of the catalysts, but exclusively affects the ionomer distribution in the electrode during electrode preparation. Limiting current measurements were used to determine the pressure independent oxygen transport resistance -primarily attributed to oxygen transport in the ionomer film -which decreases for catalysts with surface modified carbon support. Systematically lowering the ionomer to carbon ratio (I/C) from 0.65 to 0.25 revealed a maximum performance at I/C = 0.4, where an optimum between ionomer thickness and proton conductivity within the catalyst layer is obtained. From this work, it can be concluded that not only ionomer film thickness, but more importantly ionomer distribution is the key to high performance low Pt loaded electrodes.

show abstract

Experimental Method to Determine the Mass Transport Resistance of a Polymer Electrolyte Fuel Cell

Cited by 86 publications

References 10 publications

Investigating fuel-cell transport limitations using hydrogen limiting current

Investigating fuel-cell transport limitations using hydrogen limiting current

Water Management in Polymer Electrolyte Fuel Cells through Asymmetric Thermal and Mass Transport Engineering of the Micro-Porous Layers

The Key to High Performance Low Pt Loaded Electrodes

Contact Info

Product

Resources

About