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Research Papers

# A Comparison of Felt-Type and Paper-Type Gas Diffusion Layers for Polymer Electrolyte Membrane Fuel Cell Applications Using X-Ray TechniquesPUBLIC ACCESS

[+] Author and Article Information
R. Banerjee, S. Chevalier, H. Liu, J. Lee, R. Yip

Materials (TEAM) Laboratory,
Department of Mechanical and Industrial Engineering,
University of Toronto Institute for Sustainable Energy,
Faculty of Applied Science and Engineering,
University of Toronto,

K. Han

Fuel Cell R&D Group,
Eco Technology Center,
Research & Development Division,
Hyundai Motor Company,
Yongin-si 16891, Gyeonggi-do, South Korea

B. K. Hong

Fuel Cell Research Lab.,
Eco Technology Center,
Research & Development Division,
Hyundai Motor Company,
Yongin-si 16891, Gyeonggi-do, South Korea

A. Bazylak

Materials (TEAM) Laboratory,
Department of Mechanical and Industrial Engineering,
Institute for Sustainable Energy,
Faculty of Applied Science and Engineering,
University of Toronto,
e-mail: abazylak@mie.utoronto.ca

1Corresponding author.

Manuscript received July 1, 2017; final manuscript received August 19, 2017; published online October 4, 2017. Assoc. Editor: Partha P. Mukherjee.

J. Electrochem. En. Conv. Stor. 15(1), 011002 (Oct 04, 2017) (10 pages) Paper No: JEECS-17-1081; doi: 10.1115/1.4037766 History: Received July 01, 2017; Revised August 19, 2017

## Abstract

This work presents a comparison between carbon felt-type and paper-type gas diffusion layers (GDLs) for polymer electrolyte membrane (PEM) fuel cells in terms of the similarities and the differences between their microstructures and the corresponding manner in which liquid water accumulated within the microstructures during operation. X-ray computed tomography (CT) was used to investigate the microstructure of single-layered GDLs (without a microporous layer (MPL)) and bilayered GDLs (with an MPL). In-operando synchrotron X-ray radiography was used to visualize the GDL liquid water accumulation during fuel cell operation as a function of current density. The felt-type GDLs studied here exhibited a more uniform porosity in the core regions, and the carbon fibers in the substrate were more prone to MPL intrusion. More liquid water accumulated in the felt-type GDLs during fuel cell operation; however, when differentiating between the microstructural impact of felt and paper GDLs, the presence of an MPL in bilayered GDLs was the most influential factor in liquid water management.

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## Introduction

Gas diffusion layers (GDLs) in polymer electrolyte membrane (PEM) fuel cells are porous materials placed between the bipolar plate and the catalyst layer of a membrane electrode assembly (MEA). GDLs must facilitate electrical and thermal transport, reactant transport to the catalyst layer, and gaseous and liquid water transport to and from the catalyst layer. In addition to its role in facilitating these transport mechanisms, the GDL must also provide structural support for the catalyst coated membrane [14]. Paper-type GDLs and felt-type GDLs are the most commonly used GDLs in PEM fuel cells for automotive applications [5]. Additionally, state-of-the-art GDLs have a bilayered structure that is composed of a carbon fiber-based macroporous substrate and a microporous layer (MPL) [1,57]. Several detailed reviews of GDLs have been published in literature [1,2,6,8].

The primary difference between paper-type and felt-type GDLs is in the microstructure of the materials arising from their manufacturing techniques. In the paper-type GDL, an external binder is used to affix the straight carbon fibers to each other, leading to an apparently two-dimensional (planar) structure. In the felt-type GDL, however, the carbon fibers are bound together through a hydro-entangling process, which results in a three-dimensional (3D) structure with highly entangled carbon fibers [5,9]. This hydro-entangling process results in felt-type GDLs with higher permeabilities despite lower porosities [10]. However, it has been shown by several authors that the surface roughness (of the substrate) does not vary significantly between paper-type and felt-type GDLs [10,11].

A variety of ex situ and in situ techniques exist for the characterization of the GDLs for their transport properties. These include microstructure analysis through X-ray computed tomography (CT) [7,1122], measurements of breakthrough pressure [2326], diffusivity [2729], permeability [2,30,31], and thermal conductivity [3237]. Researchers have also investigated water accumulation behavior in GDLs using a variety of imaging techniques [38,39], such as neutron radiography [4045], X-ray radiography [4655], and magnetic resonance imaging [56,57]. Additionally, high-speed optical imaging has also been used to investigate the accumulation of water in the gas channels [5862].

In comparing the structural differences between GDL materials, it is of paramount importance to examine the internal microstructure (using X-ray CT) as well as the liquid water transport behavior within the GDLs. Escribano et al. [63] conducted mechanical characterization on cloth-type, felt-type, and paper-type GDLs and concluded that felt-type GDLs showed the highest resilience returning to the same thickness under consecutive compression cycles. They also presented scanning electron microscopy images of the different types of GDLs to show how the felt-type GDL had a more three-dimensional structure compared to the paper-type GDL. These findings have been further supported by the literature [1,5,45].

Fishman et al. [12] compared felt-type GDLs with paper-type and cloth-type GDLs using X-ray CT. They reported that felt-type GDLs showed a more uniform porosity in the core region of the GDL and attributed this characteristic to the hydro-entanglement process used in the fabrication of these materials. Similar observations about uniform porosity in the core region of the GDL were also made by Banerjee et al. [7]. Rofaiel et al. [9] explored the polytetrafluoroethylene (PTFE) distribution in felt-type and paper-type GDLs and concluded that a similar bimodal distribution of PTFE was observed for both felt-type and paper-type GDLs. High PTFE concentrations were observed near the outer surfaces, but low concentrations of PTFE were observed in the GDL core. The aforementioned works [1,5,7,9,1115] have exclusively investigated the microstructure differences between felt-type GDLs and paper-type GDLs. Direct visualizations of liquid water accumulation would elucidate the relationship between these microstructural differences and liquid water management in the PEM fuel cell.

X-ray radiography is a powerful technique for visualizing liquid water within an in operando fuel cell with high spatial and temporal resolutions [54,64], which allows for accurate quantification of liquid water accumulation within the GDL. The technique has been utilized by a variety of groups to isolate water in the cracks of the MPL [53,6567], quantify liquid water content in the MPL [4,6870], investigate water accumulation at the interfaces [4], identify water cluster distributions [7174], and compare water accumulation under land and channel regions [46,75,76].

In this work, both felt-type and paper-type GDLs from the same manufacturer are compared to identify the differences between the GDL microstructure and corresponding influence on liquid water accumulation through the use of X-ray tomography and X-ray radiography, respectively. Porosity profiles of uncompressed and compressed GDLs are presented and discussed for the two types of GDLs. The liquid water accumulation in the GDLs was measured in operando using synchrotron X-ray radiography, and comparisons between these materials are provided in the context of their microstructural differences.

## Methodology

This section describes the samples investigated in this work and their corresponding properties. Two characterization techniques are employed to understand the microstructure and water accumulation separately.

###### Sample Descriptions.

Four GDL samples from Sigracet® Fuel Cell Components (SGL Technologies, Meitingen, Germany) were used for the comparison study between felt-type and paper-type GDLs. Details of the GDLs are presented in Table 1, some of which were obtained from the manufacturer's specification sheet. The SGL 10 BA GDL has a felt-type carbon fiber substrate with a nominal thickness of 400 μm and does not include an MPL coating. This GDL is considered to be the base material for felt-type GDLs included in this study. The SGL 25 BA GDL has a paper-type carbon fiber substrate with a nominal thickness of 190 μm (also without an MPL coating) and is assumed to be the base material for the paper-type GDLs included in this study. Both GDLs exhibit a hydrophobic loading of 5 wt % PTFE, rendering them sufficiently hydrophobic for PEM fuel cell applications. The SGL 10 BC GDL is a bilayered GDL that is composed of SGL 10 BA coated with an MPL. Similarly, the SGL 25 BC GDL is a bilayered GDL composed of SGL 25 BA coated with an MPL. These four GDL samples were operated in the fuel cell independently so that their microstructures were compared directly to their influence on liquid water accumulation behavior.

###### Microstructure Analysis.

The GDL samples investigated in this work were imaged using a Skyscan 1172 desktop X-ray CT device (Bruker Corp., Billerica, MA). All the scans were performed at a voltage of 36 kV and a current of 222 μA. The equipment and setup were also used in prior studies relating to the microstructural analysis of GDLs [7,1215]. Figure 1 shows the schematic of the X-ray CT imaging setup, including the device used for sample mounting. Sequential projections were obtained at intervals of 0.3 deg rotations and reconstructed using NRECON® software (Bruker Corp.).

The output of the reconstruction algorithm is a three-dimensional grayscale structure, which is voxelized with the same spatial resolution as the acquired projections. Two sets of scans were performed for the microstructural analysis: uncompressed and compressed, where the same compression (thickness) was applied during in operando radiography (described in Sec. 2.3). A resolution of 2.88 μm/voxel was achieved for uncompressed GDL tomography, and a resolution of 3.3 μm/voxel was achieved for compressed GDL tomography.

The three-dimensional grayscale representation of the GDL structure is composed of the carbon fiber substrate, MPL (if applicable), and void space. To distinguish the phases and their contributions to the overall porosity of the GDL, the image was processed using an algorithm developed in-house that accounted for the expected volumes of individual components, which was estimated based on the respective areal mass and densities of each phase. Morphological image processing tools were applied in sequence and informed by the areal volumes to uniquely identify the individual phases. The reader is directed to an earlier work where the details of this algorithm were presented [7].

The individual GDL microstructures were compared using the porosity profiles of each GDL. The local porosity was calculated at each through-plane location of the GDL, and the contribution of each phase (fiber and MPL) to the solid fraction was also determined. Equations (1)(3) show the calculation of fiber solid fraction and MPL solid fraction Display Formula

(1)
Display Formula
(2)
Display Formula
(3)

The fiber solid fraction consists of the summation of voxels identified as carbon fiber materials. The MPL voxel solid fraction represents the summation of voxels identified as MPL materials. MPL voxels appear as solid in X-ray CT since the MPL nanostructure cannot be resolved with the scanning resolution used here. To account for the porous nature of the MPL, an MPL porosity of 50% ($εMPL$ = 0.5), as obtained from literature [7,78,79], was assumed. Figure 2 shows a representative porosity profile of an SGL 10 BC GDL with each of the solid fractions shown as a function of the through-plane position. The pore space (void) is represented by the white area in Fig. 2. Figure 3 shows representative cross sections in both the in-plane and through-plane directions for each of the four GDLs described in Table 1. Black represents the fibers in the substrate, orange represents the MPL phase, while white is indicative of the void space.

###### Water Accumulation.

A fuel cell customized for synchrotron X-ray radiography was used in this study. The fuel cells were assembled with Nafion® HP membrane (DuPont Company, Wilmington, DE) coated with 0.3 mg Pt/cm2 of Pt/C catalyst, as obtained from Ion Power Inc. (New Castle, DE). The same catalyst loading and GDL were used on both the anode and the cathode sides. The four GDLs described in Table 1 were individually tested in separate fuel cells. Constant current density operation was applied to the four fuel cells, and the current density was increased by intervals of 0.5 A/cm2 up to 3.0 A/cm2. The MEA had an active area of 68 mm2 (8.0 mm × 8.5 mm) and was placed in between two graphite flow field plates with parallel channels and lands (square cross sections) that were both 0.5 mm wide. The channels are the square flow fields through which the reactant gases were introduced. The lands are solid regions in the flow field, which provide structural support to the MEA as well as conductive pathways for the electrical current to flow.

For all the cases, the fuel cell was operated at 60 °C with a gas inlet relative humidity of 100% and a backpressure of 200 kPa (absolute), controlled by a Scribner 850 e fuel cell test stand (Scribner Associates Inc., Southern Pines, NC). These conditions were used to intentionally exacerbate the accumulation of liquid water in the GDL to observe the structural influence on liquid water transport in the absence of membrane dehydration effects [80]. The cell was supplied with a constant gas flow rate of 1.0 l/min, and a cathode stoichiometric ratio of 80 was reached at a current density of 1.0 A/cm2. The high stoichiometric ratio was prescribed to purge liquid water from the channels at all current densities and ensure that our observations were not influenced by channel liquid water blockage. At each current density, the cell was held for 15 min to reach a steady-state liquid water behavior [54,81].

Water accumulation in the GDL was observed in operando using synchrotron X-ray radiography. The radiography experiments were performed at the Biomedical Imaging and Therapy–Bending Magnet (05B1-1) beamline at the Canadian Light Source Inc., (CLSi), in Saskatoon, SK, Canada [82]. The radiographic imaging was conducted at an energy level of 24 keV, and the images were captured using an AA40 scintillator (Hamamatsu Photonics, Japan) and a Hamamatsu ORCA Flash 4.0 coupled charge device camera (Hamamatsu Photonics, Shizuoka, Japan). A pixel resolution of 6.5 μm and a frame rate of 0.33 frames per second were achieved. Figure 4 shows a schematic of the imaging setup for the fuel cell, with an example radiograph presented as a reference.

Reference images were obtained when the cell was operated at a current density of 0 A/cm2 (i.e., open circuit voltage) such that liquid water was not present in the system. Test images were obtained continuously during the cell operation, which were compared with the reference images according to the Beer–Lambert law (Eq. (4)) to quantify the liquid water content present in the system [83,84]. Display Formula

(4)

In Eq. (4), tw is the thickness of water, μw is the linear attenuation coefficient of water, and Idry and Iwet are the intensities of fuel cells operated under dry and wet conditions, respectively. The processing is completed using algorithms developed in-house [83,84].

The data presented in this work were obtained at steady-state. Liquid water content was measured at the end of the 15 min period of steady-state operation, and the data presented here are an average of 20 frames (1 min of operation). The values of liquid water thickness obtained from the radiographs were normalized by the thickness of the GDL traversed by the beam.

## Results and Discussion

In this section, the results of both the microstructure analysis and the water accumulation studies are presented for the four GDLs. A comparison is made between the felt-type and paper-type GDLs included in this study, and the impact of their microstructural differences on the water accumulation in the GDL is explored.

###### Microstructure Analysis.

Figure 5(a) shows the solid fraction profiles of uncompressed GDLs for each of the four GDLs investigated, properties of which have been presented in Table 1. For single-layered GDLs (SGL 25 BA and SGL 10 BA), there is only one profile which shows the overall porosity of the sample. This overall porosity is the result of the fiber solid fraction, which is the only component contributing to the solid fraction. However, for the bilayered GDLs (SGL 25 BC and SGL 10 BC), three profiles have been presented in the figures. The definition of these porosity profiles is given in Equations (1)(3) as discussed in Sec. 2.2. The white region above the solid fraction profiles represents the void space in the porous medium.

For all of the GDLs, the porosity is observed to be high at the edges of the GDLs and decreases to reach low porosities in the core of the GDL. For SGL 10 BA (felt-type), the porosity profile shows high porosity at the edges and gradually decreases to a value of approximately 0.83 toward the core of the GDL. The core region (from 100 to 300 μm) of the GDL exhibited an average porosity of εcore = 0.83 ± 0.003. Similarly, SGL 25 BA (paper-type GDL) also exhibited high porosities at the edges, and the porosity decreased toward the core of the GDL. The key difference between the felt-type and the paper-type GDL was observed in the cores of the GDLs, where the paper-type GDL (SGL 25 BA) exhibited a nonuniform porosity profile, with the minima located at 60 μm from one of the outer surfaces and had a value of εcore = 0.80 ± 0.003 (core region was 50 μm thick).

SGL 10 BC and SGL 25 BC are composed of SGL 10 BA and SGL 25 BA, respectively, as the fibrous substrates with MPL coatings. The MPLs were coated on one side of the substrate (by the manufacturer) so that the MPL acts as the interface with the catalyst layers of the MEA. The bulk MPL is defined as the region of the MPL in which there are very few carbon fibers. This region is smaller in SGL 10 BC compared to SGL 25 BC. This comparative difference in the bulk MPL thickness is further supported by the nominal thickness measurement provided by the manufacturer (Table 1). The SGL 25 BC GDL is 45 μm thicker than SGL 25 BA, which can be attributed to the MPL thickness. The SGL 10 BC GDL is only 20 μm thicker than SGL 10 BA, which is also attributed to the MPL thickness in SGL 10 BC.

In the bilayered GDLs, the thickness of the MPL was categorized into two sections: one section resided outside the boundaries of the fibrous substrate and the other section of the MPL intruded the fibrous substrate (i.e., a mixed zone of MPL and carbon fiber substrate). The total MPL thickness was calculated from the porosity profiles and defined as the thickness of the GDL whereby void voxels within the GDL consisted of less than 50% of the total GDL voxels [75]. Table 2 shows the thickness of the MPL as calculated using this methodology for both the GDLs in uncompressed and compressed states. The extra overlap between the MPL and the substrate was calculated as the difference between the uncompressed and compressed thicknesses of the MPL (also shown in Table 2). For SGL 10 BC, this increased overlap (MPL intrusion into substrate) was calculated as 47 μm, while that for SGL 25 BC is 19 μm. This shows that the paper-type GDL is less prone to MPL intrusion into the fibrous substrate.

Figure 5(b) shows the porosity profile of the GDLs studied under compression. Each GDL was compressed by 20–25% of its uncompressed thickness, a practice that has been shown to provide the best contact between the layers without increasing mass transport resistances [8587].

The porosity profile of SGL 10 BA shows a relatively uniform porosity throughout the thickness, because the high porosity regions near the edge were eliminated due to the application of compression. The edges still demonstrated higher porosities than the core regions. The porosity profile of SGL 25 BA exhibited similar changes as was observed in SGL 10 BA upon compression. The same low porosity region was observed with a decreased porosity of ε = 0.74, with the minimum located 30 μm from the GDL surface.

As expected after compression, the SGL 10 BC GDL demonstrated a significantly lower porosity than when uncompressed. It is interesting to note that the minimum combined porosity of SGL 10 BC decreased to ε = 0.5. Although the SGL 25 BC GDL also demonstrated a decrease in porosity with compression, its lowest porosity region has a combined porosity of ε = 0.6. The combined porosity of uncompressed SGL 10 BC was higher (ε = 0.74) than that of SGL 25 BC (ε = 0.62) as shown in Fig. 5. The fibrous substrate extended throughout the MPL of SGL 10 BC. For SGL 25 BC, the bulk MPL region extended to 30 μm, within which carbon fibers were entirely absent. From observation, the MPL coated on the felt-type GDL is susceptible to penetration by the felt-type carbon fiber region under compression. Carbon fibers embedded in the MPL may come into contact with the catalyst layer and puncture the membrane and lead to durability and performance losses.

###### Water Accumulation in the Gas Diffusion Layers.

Figure 6 shows the normalized liquid water thickness measured in SGL 10 BA and SGL 25 BA during operation at the current densities of 0.5, 1.0, and 1.5 A/cm2. The through-plane water accumulation in both the anode and cathode GDLs are shown for an increasing range of current densities (0.5, 1.0, and 1.5 A/cm2) to identify the onset of liquid water accumulation. The water in the GDL regions under the channel and land regions were characterized separately, since significant differences in water accumulation between the two regions were observed, which is in agreement with the literature [75,76,88]. The shaded gray region indicates the position of the polymer electrolyte membrane, which is 26 μm thick. The majority of the conclusions will be drawn from the cathode GDL as the cathode typically exhibits water management challenges [89,90], which results in higher oxygen transport resistances [75,88,91] and larger performance losses compared to the anode.

Figures 6(a) and 6(b) show the normalized water thickness in the GDL region under the channel for the felt-type GDL (SGL 10 BA) and the paper-type GDL (SGL 25 BA), respectively. In Fig. 6(a), the higher water content in the felt-type GDL under the channel is observed, with significant water accumulation near the catalyst layer. This high water content is attributed to the high porosity in SGL 10 BA and large pores that are prone to flooding. This flooding was the primary mode of cell failure for the felt-type GDL. This flooding phenomenon was mitigated in the paper-type GDL as shown in Fig. 6(b), which shows an insignificant accumulation of water in the GDL region under the channel.

Figures 6(c) and 6(d) show the normalized water thickness in the GDL region under the land for the felt-type GDL (SGL 10 BA) and the paper-type GDL (SGL 25 BA), respectively. The average water quantity in the felt-type GDL under the channel is similar to that under the land region while the paper-type GDL shows a significant difference of water quantity between the channel and land regions. The relatively uniform distribution of water between the land and channel regions is attributed to the heterogeneous 3D structure of the felt-type GDL. The water accumulation in the land region of the paper-type GDL is significantly higher than that in the channel region of the GDL. This nonuniform liquid water distribution is attributed to a temperature gradient between the land and channel regions resulting in condensation in the cooler land region [75,76]. The lack of convective drag at the land-GDL interface also inhibits effective water removal. It is noteworthy that the overall water content in the felt-type GDL is still higher than that in the paper-type GDL under the land region. The low porosity region in SGL 25 BA (at 100 μm) as shown in Fig. 5(b) is not a preferential region for liquid water accumulation. The SGL 10 BA GDL does not exhibit a similar low porosity region to discourage liquid water accumulation.

Figure 7 shows the normalized liquid water thicknesses for the bilayered GDLs corresponding to the felt-type and paper-type GDLs, SGL 10 BC and SGL 25 BC, respectively. Figure 7(a) shows the liquid water content in the channel region of the felt-type bilayered GDL (SGL 10 BC), and Fig. 7(b) exhibits the water content in the same region of the paper-type bilayered GDL (SGL 25 BC). The water content in the bilayered GDLs (Fig. 7) is generally lower than that in the single-layered GDLs. This lower liquid water content has been attributed to the enhancement of vapor phase transport [68,92] and back diffusion through the membrane to the anode [93,94].

Figures 7(c) and 7(d) show the normalized liquid water in the GDL under the land region for both bilayered GDLs, corresponding to the felt-type (SGL 10 BC) and paper-type (SGL 25 BC) GDLs, respectively. In both the GDLs, less water was present near the catalyst layer/PEM interface, which was attributed to the presence of the MPL. The water content increased near the land region, which was also observed in the single-layered GDLs. In the bilayered GDLs, the difference in water content between the felt-type and the paper-type GDLs was not significant as the impact of the MPL dominated liquid water accumulation in the GDL (over the structural differences between the carbon fiber substrates).

As shown in Figs. 7(c) and 7(d), more liquid water was observed near the catalyst layer in the case of SGL 25 BC compared to the same region in SGL 10 BC, which is in contrast to the single-layered GDLs. The lower liquid water content at the catalyst layer in SGL 10 BC was attributed to the larger thermal gradient (compared to SGL 25 BC) that arises from the thicker GDL, which promotes vapor phase transport [68] through the MPL.

The observations from Fig. 6 reveal that the main structural differences in the felt-type and paper-type GDLs have a strong impact on the liquid water accumulation in the GDL when used as single-layered GDLs. However, with the application of the MPL, the influence of the MPL dominates over the impact of the structural differences of the fibrous substrate, in relation to the water accumulation in the GDL.

## Conclusions

In this work, felt-type and paper-type Sigracet® GDLs were compared in terms of their microstructure and related capacities to hold liquid water during operation. X-ray computed tomography was used to characterize the GDL microstructure in the form of through-plane porosity profiles. In operando synchrotron X-ray radiography was also performed with a custom fuel cell to observe liquid water accumulation patterns within the GDLs. The main findings are summarized below:

• Felt-type GDLs exhibited a more uniform porosity compared to the paper-type GDLs.

• In the absence of compression, the paper-type GDL exhibited a thicker MPL due to the MPL intrusion into the paper-type carbon fiber substrate.

• Under compression, the carbon fiber substrate of the felt-type GDL was more susceptible to penetrating the MPL, which could lead to a significant risk of MEA damage during compression.

• More significant water accumulation was observed in felt-type GDLs without MPLs.

• Both felt- and paper-type MPL-coated GDLs (bilayered) exhibited similar liquid water content, and we attribute this to the dominating presence of the MPL.

The work presented here uses the microstructure analysis and the water accumulation in the GDL to evaluate the applicability of felt-type and paper-type GDLs in PEM fuel cells. For bilayered GDLs, the impact of the MPL was more significant than the influence of the structural differences of the substrate materials. This work can be used to develop more robust and effective GDLs with enhanced liquid water transport capabilities for PEM fuel cell applications.

## Acknowledgements

Financial support from the Natural Sciences and Engineering Research Council of Canada (NSERC), the NSERC Discovery Accelerator Program, the NSERC Canada Research Chairs Program, the Ontario Ministry of Research and Innovation Early Researcher Award, the Canada Foundation for Innovation, and the R&D Collaboration Program (R-152351) of Hyundai Motor Company are gratefully acknowledged. Graduate scholarships to Jongmin Lee from the Mercedes-Benz Canada Graduate Fellowship in Fuel Cell Research, the HATCH Graduate Scholarship, and the David Sanborn Scott & Ron D. Venter Fellowship are gratefully acknowledged. Graduate scholarships to Hang Liu from the University of Toronto Connaught International Scholarship for Doctoral Students are gratefully acknowledged.

The authors would also like to thank Dr. Shiang Law and Prof. Mark Kortschot from the Department of Chemical Engineering & Applied Chemistry as well as Prof. Mohini Sain from the Faculty of Forestry for providing the generous access to their X-CT equipment.

## Funding Data

• Natural Sciences and Engineering Research Council of Canada (Canada Research Ch, Discovery Accelera, and Discovery Grant Pro).

• Ontario Ministry of Economic Development and Innovation (Early Researcher Aw).

• Hyundai Motor Company - R&D Collaboration Program (Grant No. R-152351).

## Nomenclature

• CLSi =

• CT =

computed tomography

• GDL =

gas diffusion layer

• MEA =

membrane electrode assembly

• MPL =

microporous layer

• PEM =

polymer electrolyte membrane

• PTFE =

polytetrafluoroethylene

## References

Mathias, M. F. , Roth, J. , Fleming, J. , and Lehnert, W. , 2010, “ Diffusion Media Materials and Characterisation,” Handbook of Fuel Cells, Wiley, Chichester, UK. [PubMed] [PubMed]
Cindrella, L. , Kannan, A. M. , Lin, J. F. , Saminathan, K. , Ho, Y. , Lin, C. W. , and Wertz, J. , 2009, “ Gas Diffusion Layer for Proton Exchange Membrane Fuel Cells—A Review,” J. Power Sources, 194(1), pp. 146–160.
Hung, C.-H. , Chiu, C.-H. , Wang, S.-P. , Chiang, I.-L. , and Yang, H. , 2012, “ Ultra Thin Gas Diffusion Layer Development for PEMFC,” Int. J. Hydrogen Energy, 37(17), pp. 12805–12812.
Lee, J. , Chevalier, S. , Banerjee, R. , Antonacci, P. , Ge, N. , Yip, R. , Kotaka, T. , Tabuchi, Y. , and Bazylak, A. , 2017, “ Investigating the Effects of Gas Diffusion Layer Substrate Thickness on Polymer Electrolyte Membrane Fuel Cell Performance Via Synchrotron X-Ray Radiography,” Electrochim. Acta, 236, pp. 161–170.
Göbel, M. , Godehardt, M. , and Schladitz, K. , 2017, “ Multi-Scale Structural Analysis of Gas Diffusion Layers,” J. Power Sources, 355, pp. 8–17.
Park, S. , Lee, J.-W. , and Popov, B. N. , 2012, “ A Review of Gas Diffusion Layer in PEM Fuel Cells: Materials and Designs,” Int. J. Hydrogen Energy, 37(7), pp. 5850–5865.
Banerjee, R. , Hinebaugh, J. , Liu, H. , Yip, R. , Ge, N. , and Bazylak, A. , 2016, “ Heterogeneous Porosity Distributions of Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layer Materials With Rib-Channel Compression,” Int. J. Hydrogen Energy, 41(33), pp. 14885–14896.
Arvay, A. , Yli-Rantala, E. , Liu, C.-H. , Peng, X.-H. , Koski, P. , Cindrella, L. , Kauranen, P. , Wilde, P. M. , and Kannan, A. M. , 2012, “ Characterization Techniques for Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells—A Review,” J. Power Sources, 213, pp. 317–337.
Rofaiel, A. , Ellis, J. S. , Challa, P. R. , and Bazylak, A. , 2012, “ Heterogeneous Through-Plane Distributions of Polytetrafluoroethylene in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers,” J. Power Sources, 201, pp. 219–225.
El-Kharouf, A. , Rees, N. V. , and Steinberger-Wilckens, R. , 2014, “ Gas Diffusion Layer Materials and Their Effect on Polymer Electrolyte Fuel Cell Performance—Ex Situ and In Situ Characterization,” Fuel Cells, 14(5), pp. 735–741.
George, M. , Fishman, Z. , Botelho, S. , and Bazylak, A. , 2016, “ Micro-Computed Tomography-Based Profilometry for Characterizing the Surface Roughness of Microporous Layer-Coated Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers,” J. Electrochem. Soc., 163(8), pp. F832–F841.
Fishman, Z. , Hinebaugh, J. , and Bazylak, A. , 2010, “ Microscale Tomography Investigations of Heterogeneous Porosity Distributions of PEMFC GDLs,” J. Electrochem. Soc., 157(11), pp. B1643–B1650.
Fishman, Z. , and Bazylak, A. , 2011, “ Heterogeneous Through-Plane Distributions of Tortuosity, Effective Diffusivity, and Permeability for PEMFC GDLs,” J. Electrochem. Soc., 158(2), pp. B247–B252.
Fishman, Z. , and Bazylak, A. , 2011, “ Heterogeneous Through-Plane Porosity Distributions for Treated PEMFC GDLs—I: PTFE Effect,” J. Electrochem. Soc., 158(8), pp. B841–B845.
Fishman, Z. , and Bazylak, A. , 2011, “ Heterogeneous Through-Plane Porosity Distributions for Treated PEMFC GDLs—II: Effect of MPL Cracks,” J. Electrochem. Soc., 158(8), pp. B846–B851.
Pfrang, A. , Veyret, D. , Sieker, F. , and Tsotridis, G. , 2010, “ X-Ray Computed Tomography of Gas Diffusion Layers of PEM Fuel Cells: Calculation of Thermal Conductivity,” Int. J. Hydrogen Energy, 35(8), pp. 3751–3757.
Flückiger, R. , Marone, F. , Stampanoni, M. , Wokaun, A. , and Büchi, F. N. , 2011, “ Investigation of Liquid Water in Gas Diffusion Layers of Polymer Electrolyte Fuel Cells Using X-Ray Tomographic Microscopy,” Electrochim. Acta, 56(5), pp. 2254–2262.
Markötter, H. , Manke, I. , Krüger, P. , Arlt, T. , Haussmann, J. , Klages, M. , Riesemeier, H. , Hartnig, C. , Scholta, J. , and Banhart, J. , 2011, “ Investigation of 3D Water Transport Paths in Gas Diffusion Layers by Combined in-Situ Synchrotron X-Ray Radiography and Tomography,” Electrochem. Commun., 13(9), pp. 1001–1004.
Epting, W. K. , Gelb, J. , and Litster, S. , 2012, “ Resolving the Three-Dimensional Microstructure of Polymer Electrolyte Fuel Cell Electrodes Using Nanometer-Scale X-Ray Computed Tomography,” Adv. Funct. Mater., 22(3), pp. 555–560.
James, J. P. , Choi, H.-W. , and Pharoah, J. G. , 2012, “ X-Ray Computed Tomography Reconstruction and Analysis of Polymer Electrolyte Membrane Fuel Cell Porous Transport Layers,” Int. J. Hydrogen Energy, 37(23), pp. 18216–18230.
Wargo, E. A. , Schulz, V. P. , Çeçen, A. , Kalidindi, S. R. , and Kumbur, E. C. , 2013, “ Resolving Macro- and Micro-Porous Layer Interaction in Polymer Electrolyte Fuel Cells Using Focused Ion Beam and X-Ray Computed Tomography,” Electrochim. Acta, 87, pp. 201–212.
Wargo, E. A. , Kotaka, T. , Tabuchi, Y. , and Kumbur, E. C. , 2013, “ Comparison of Focused Ion Beam Versus Nano-Scale X-Ray Computed Tomography for Resolving 3-D Microstructures of Porous Fuel Cell Materials,” J. Power Sources, 241, pp. 608–618.
Lu, Z. , Daino, M. M. , Rath, C. , and Kandlikar, S. G. , 2010, “ Water Management Studies in PEM Fuel Cells—Part III: Dynamic Breakthrough and Intermittent Drainage Characteristics From GDLs With and Without MPLs,” Int. J. Hydrogen Energy, 35(9), pp. 4222–4233.
Lu, Z. , and Patterson, J. , 2013, “ Investigation of Water Breakthrough and Flow in Gas Diffusion Layers and Relavance to Fuel Cell Water Management,” ECS Trans., 50(2), pp. 487–501.
Mortazavi, M. , and Tajiri, K. , 2014, “ Liquid Water Breakthrough Pressure Through Gas Diffusion Layer of Proton Exchange Membrane Fuel Cell,” Int. J. Hydrogen Energy, 39(17), pp. 9409–9419.
Kim, J. , Je, J. , Kim, T. , Kaviany, M. , Son, S. Y. , and Kim, M. , 2012, “ Breakthrough/Drainage Pressures and X-Ray Water Visualization in Gas Diffusion Layer of PEMFC,” Curr. Appl. Phys., 12(1), pp. 105–108.
Flückiger, R. , Freunberger, S. A. , Kramer, D. , Wokaun, A. , Scherer, G. G. , and Büchi, F. N. , 2008, “ Anisotropic, Effective Diffusivity of Porous Gas Diffusion Layer Materials for PEFC,” Electrochim. Acta, 54(2), pp. 551–559.
LaManna, J. M. , and Kandlikar, S. G. , “ Determination of Effective Water Vapor Diffusion Coefficient in PEMFC Gas Diffusion Layers,” Int. J. Hydrogen Energy, 28, pp. 5021–5029.
Hwang, G. S. , and Weber, A. Z. , 2012, “ Effective-Diffusivity Measurement of Partially-Saturated Fuel-Cell Gas-Diffusion Layers,” J. Electrochem. Soc., 159(11), pp. F683–F692.
Gostick, J. T. , Fowler, M. W. , Pritzker, M. D. , Ioannidis, M. A. , and Behra, L. M. , 2006, “ In-Plane and Through-Plane Gas Permeability of Carbon Fiber Electrode Backing Layers,” J. Power Sources, 162(1), pp. 228–238.
Gurau, V. , Bluemle, M. J. , De Castro, E. S. , Tsou, Y.-M. , Zawodzinski, T. A., Jr. , and Mann, J. A., Jr. , 2007, “ Characterization of Transport Properties in Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells—2: Absolute Permeability,” J. Power Sources, 165(2), pp. 793–802.
Sadeghifar, H. , Djilali, N. , and Bahrami, M. , 2014, “ Effect of Polytetrafluoroethylene (PTFE) and Micro Porous Layer (MPL) on Thermal Conductivity of Fuel Cell Gas Diffusion Layers: Modeling and Experiments,” J. Power Sources, 248, pp. 632–641.
Alhazmi, N. , Ismail, M. S. , Ingham, D. B. , Hughes, K. J. , Ma, L. , and Pourkashanian, M. , 2013, “ The In-Plane Thermal Conductivity and the Contact Resistance of the Components of the Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cells,” J. Power Sources, 241, pp. 136–145.
Unsworth, G. , Zamel, N. , and Li, X. , 2012, “ Through-Plane Thermal Conductivity of the Microporous Layer in a Polymer Electrolyte Membrane Fuel Cell,” Int. J. Hydrogen Energy, 37(6), pp. 5161–5169.
Radhakrishnan, A. , Lu, Z. , and Kandlikar, S. G. , 2010, “ Effective Thermal Conductivity of Gas Diffusion Layers Used in PEMFC: Measured With Guarded-Hot-Plate Method and Predicted by a Fractal Model,” ECS Trans., 33(1), pp. 1163–1176.
Khandelwal, M. , and Mench, M. M. , 2006, “ Direct Measurement of Through-Plane Thermal Conductivity and Contact Resistance in Fuel Cell Materials,” J. Power Sources, 161(2), pp. 1106–1115.
Xu, G. , LaManna, J. M. , Clement, J. T. , and Mench, M. M. , 2014, “ Direct Measurement of Through-Plane Thermal Conductivity of Partially Saturated Fuel Cell Diffusion Media,” J. Power Sources, 256, pp. 212–219.
Bazylak, A. , 2009, “ Liquid Water Visualization in PEM Fuel Cells: A Review,” Int. J. Hydrogen Energy, 34(9), pp. 3845–3857.
Kim, S.-G. , and Lee, S.-J. , 2013, “ A Review on Experimental Evaluation of Water Management in a Polymer Electrolyte Fuel Cell Using X-Ray Imaging Technique,” J. Power Sources, 230, pp. 101–108.
Pekula, N. , Heller, K. , Chuang, P. A. , Turhan, A. , Mench, M. M. , Brenizer, J. S. , and Ünlü, K. , 2005, “ Study of Water Distribution and Transport in a Polymer Electrolyte Fuel Cell Using Neutron Imaging,” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 542, Elsevier, Amsterdam, The Netherlands, pp. 134–141.
Boillat, P. , Kramer, D. , Seyfang, B. C. , Frei, G. , Lehmann, E. , Scherer, G. G. , Wokaun, A. , Ichikawa, Y. , Tasaki, Y. , and Shinohara, K. , 2008, “ In Situ Observation of the Water Distribution Across a PEFC Using High Resolution Neutron Radiography,” Electrochem. Commun., 10(4), pp. 546–550.
Hickner, M. A. , Siegel, N. P. , Chen, K. S. , Hussey, D. S. , Jacobson, D. L. , and Arif, M. , 2008, “ In Situ High-Resolution Neutron Radiography of Cross-Sectional Liquid Water Profiles in Proton Exchange Membrane Fuel Cells,” J. Electrochem. Soc., 155(4), pp. B427–B434.
Lu, Z. , Waldecker, J. , Xie, X. , Lai, M.-C. , Hussey, D. S. , and Jacobson, D. L. , 2013, “ Investigation of Water Transport in Perforated Gas Diffusion Layer by Neutron Radiography,” ECS Trans., 58(1), pp. 315–324.
Kotaka, T. , Tabuchi, Y. , Pasaogullari, U. , and Wang, C.-Y. , 2014, “ Impact of Interfacial Water Transport in PEMFCs on Cell Performance,” Electrochim. Acta, 146, pp. 618–629.
Cooper, N. J. , Santamaria, A. D. , Becton, M. K. , and Park, J. W. , “ Neutron Radiography Measurements of in-Situ PEMFC Liquid Water Saturation in 2D & 3D Morphology Gas Diffusion Layers,” Int. J. Hydrogen Energy, 42(25), pp. 169269–16278.
Manke, I. , Hartnig, C. , Grünerbel, M. , Lehnert, W. , Kardjilov, N. , Haibel, A. , Hilger, A. , Banhart, J. , and Riesemeier, H. , 2007, “ Investigation of Water Evolution and Transport in Fuel Cells With High Resolution Synchrotron X-Ray Radiography,” Appl. Phys. Lett., 90(17), p. 174105.
Hinebaugh, J. , Lee, J. , and Bazylak, A. , 2012, “ Visualizing Liquid Water Evolution in a PEM Fuel Cell Using Synchrotron X-Ray Radiography,” J. Electrochem. Soc., 159(12), pp. F826–F830.
Lee, J. , Hinebaugh, J. , and Bazylak, A. , 2013, “ Synchrotron X-Ray Radiographic Investigations of Liquid Water Transport Behavior in a PEMFC With MPL-Coated GDLs,” J. Power Sources, 227, pp. 123–130.
Eller, J. , Roth, J. , Marone, F. , Stampanoni, M. , Wokaun, A. , and Büchi, F. N. , 2011, “ Towards Ultra-Fast X-Ray Tomographic Microscopy of Liquid Water in PEFC,” ECS Trans., 41(1), pp. 387–394.
Eller, J. , Rosén, T. , Marone, F. , Stampanoni, M. , Wokaun, A. , and Büchi, F. N. , 2011, “ Progress in In Situ X-Ray Tomographic Microscopy of Liquid Water in Gas Diffusion Layers of PEFC,” J. Electrochem. Soc., 158(8), pp. B963–B970.
Sasabe, T. , Tsushima, S. , and Hirai, S. , 2010, “ In-Situ Visualization of Liquid Water in an Operating PEMFC by Soft X-Ray Radiography,” Int. J. Hydrogen Energy, 35(20), pp. 11119–11128.
Deevanhxay, P. , Sasabe, T. , Tsushima, S. , and Hirai, S. , 2011, “ Investigation of Water Accumulation and Discharge Behaviors With Variation of Current Density in PEMFC by High-Resolution Soft X-Ray Radiography,” Int. J. Hydrogen Energy, 36(17), pp. 10901–10907.
Haußmann, J. , Markötter, H. , Alink, R. , Bauder, A. , Dittmann, K. , Manke, I. , and Scholta, J. , 2013, “ Synchrotron Radiography and Tomography of Water Transport in Perforated Gas Diffusion Media,” J. Power Sources, 239, pp. 611–622.
Banerjee, R. , Ge, N. , Lee, J. , George, M. G. , Chevalier, S. , Liu, H. , Shrestha, P. , Muirhead, D. , and Bazylak, A. , 2017, “ Transient Liquid Water Distributions in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers Observed Through In-Operando Synchrotron X-Ray Radiography,” J. Electrochem. Soc., 164(2), pp. F154–F162.
Tötzke, C. , Gaiselmann, G. , Osenberg, M. , Bohner, J. , Arlt, T. , Markötter, H. , Hilger, A. , Wieder, F. , Kupsch, A. , Müller, B. R. , Hentschel, M. P. , Banhart, J. , Schmidt, V. , Lehnert, W. , and Manke, I. , 2014, “ Three-Dimensional Study of Compressed Gas Diffusion Layers Using Synchrotron X-Ray Imaging,” J. Power Sources, 253, pp. 123–131.
Dunbar, Z. , and Masel, R. I. , 2007, “ Quantitative MRI Study of Water Distribution During Operation of a PEM Fuel Cell Using Teflon® Flow Fields,” J. Power Sources, 171(2), pp. 678–687.
Minard, K. R. , Viswanathan, V. V. , Majors, P. D. , Wang, L.-Q. , and Rieke, P. C. , 2006, “ Magnetic Resonance Imaging (MRI) of PEM Dehydration and Gas Manifold Flooding During Continuous Fuel Cell Operation,” J. Power Sources, 161(2), pp. 856–863.
Tüber, K. , Pócza, D. , and Hebling, C. , 2003, “ Visualization of Water Buildup in the Cathode of a Transparent PEM Fuel Cell,” J. Power Sources, 124(2), pp. 403–414.
Hussaini, I. S. , and Wang, C.-Y. , 2009, “ Visualization and Quantification of Cathode Channel Flooding in PEM Fuel Cells,” J. Power Sources, 187(2), pp. 444–451.
Sergi, J. M. , Lu, Z. , and Kandlikar, S. G. , 2009, “ In Situ Characterization of Two-Phase Flow in Cathode Channels of an Operating PEM Fuel Cell With Visual Access,” ASME Paper No. ICNMM2009-82140.
Sergi, J. M. , and Kandlikar, S. G. , 2011, “ Quantification and Characterization of Water Coverage in PEMFC Gas Channels Using Simultaneous Anode and Cathode Visualization and Image Processing,” Int. J. Hydrogen Energy, 36(19), pp. 12381–12392.
Banerjee, R. , and Kandlikar, S. G. , 2014, “ Liquid Water Quantification in the Cathode Side Gas Channels of a Proton Exchange Membrane Fuel Cell Through Two-Phase Flow Visualization,” J. Power Sources, 247, pp. 9–19.
Escribano, S. , Blachot, J.-F. , Ethève, J. , Morin, A. , and Mosdale, R. , 2006, “ Characterization of PEMFCs Gas Diffusion Layers Properties,” J. Power Sources, 156(1), pp. 8–13.
Chevalier, S. , Ge, N. , George, M. G. , Lee, J. , Banerjee, R. , Liu, H. , Shrestha, P. , Muirhead, D. , Hinebaugh, J. , Tabuchi, Y. , Kotaka, T. , and Bazylak, A. , 2017, “ Synchrotron X-Ray Radiography as a Highly Precise and Accurate Method for Measuring the Spatial Distribution of Liquid Water in Operating Polymer Electrolyte Membrane Fuel Cells,” J. Electrochem. Soc., 164(2), pp. F107–F114.
Sasabe, T. , Deevanhxay, P. , Tsushima, S. , and Hirai, S. , 2011, “ Soft X-Ray Visualization of the Liquid Water Transport Within the Cracks of Micro Porous Layer in PEMFC,” Electrochem. Commun., 13(6), pp. 638–641.
Deevanhxay, P. , Sasabe, T. , Tsushima, S. , and Hirai, S. , 2013, “ Observation of Dynamic Liquid Water Transport in the Microporous Layer and Gas Diffusion Layer of an Operating PEM Fuel Cell by High-Resolution Soft X-Ray Radiography,” J. Power Sources, 230, pp. 38–43.
Markötter, H. , Haußmann, J. , Alink, R. , Tötzke, C. , Arlt, T. , Klages, M. , Riesemeier, H. , Scholta, J. , Gerteisen, D. , Banhart, J. , and Manke, I. , 2013, “ Influence of Cracks in the Microporous Layer on the Water Distribution in a PEM Fuel Cell Investigated by Synchrotron Radiography,” Electrochem. Commun., 34, pp. 22–24.
Ge, N. , Chevalier, S. , Lee, J. , Yip, R. , Banerjee, R. , George, M. G. , Liu, H. , Lee, C. , Fazeli, M. , Antonacci, P. , Kotaka, T. , Tabuchi, Y. , and Bazylak, A. , 2017, “ Non-Isothermal Two-Phase Transport in a Polymer Electrolyte Membrane Fuel Cell With Crack-Free Microporous Layers,” Int. J. Heat Mass Transfer, 107, pp. 418–431.
Antonacci, P. , Chevalier, S. , Lee, J. , Ge, N. , Hinebaugh, J. , Yip, R. , Tabuchi, Y. , Kotaka, T. , and Bazylak, A. , 2016, “ Balancing Mass Transport Resistance and Membrane Resistance When Tailoring Microporous Layer Thickness for Polymer Electrolyte Membrane Fuel Cells Operating at High Current Densities,” Electrochim. Acta, 188, pp. 888–897.
Lee, J. , Yip, R. , Antonacci, P. , Ge, N. , Kotaka, T. , Tabuchi, Y. , and Bazylak, A. , 2015, “ Synchrotron Investigation of Microporous Layer Thickness on Liquid Water Distribution in a PEM Fuel Cell,” J. Electrochem. Soc., 162(7), pp. F669–F676.
Zenyuk, I. V. , Parkinson, D. Y. , Hwang, G. , and Weber, A. Z. , 2015, “ Probing Water Distribution in Compressed Fuel-Cell Gas-Diffusion Layers Using X-Ray Computed Tomography,” Electrochem. Commun., 53, pp. 24–28.
Eller, J. , and Büchi, F. N. , 2016, “ Characterization of Water Cluster Connectivity and Fluid Transport in PEFC Gas Diffusion Layers,” Meet. Abstr., MA2016-02(38), p. 2494.
Eller, J. , 2013, “ X-Ray Tomographic Microscopy of Polymer Electrolyte Fuel Cells,” Ph.D. thesis, ETH Zürich, Zürich, Switzerland.
Hinebaugh, J. , Lee, J. , Mascarenhas, C. , and Bazylak, A. , 2015, “ Quantifying Percolation Events in PEM Fuel Cell Using Synchrotron Radiography,” Electrochim. Acta, 184, pp. 417–426.
Muirhead, D. , Banerjee, R. , Lee, J. , George, M. G. , Ge, N. , Liu, H. , Chevalier, S. , Hinebaugh, J. , and Bazylak, A. , 2017, “ Simultaneous Characterization of Oxygen Transport Resistance and Spatially Resolved Liquid Water Saturation at High-Current Density of Polymer Electrolyte Membrane Fuel Cells With Varied Cathode Relative Humidity,” Int. J. Hydrogen Energy (Submitted).
Liu, H. , George, M. G. , Banerjee, R. , Ge, N. , Lee, J. , Muirhead, D. , Shrestha, P. , Chevalier, S. , Hinebaugh, J. , Zeis, R. , Messerschmidt, M. , Scholta, J. , and Bazylak, A. , 2017, “ Accelerated Degradation of Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers—Part 2: Steady State Liquid Water Distributions With in Operando Synchrotron X-Ray Radiography,” J. Electrochem. Soc., 164, pp. F704–F713.
Schweiss, R. , Meiser, C. , Damjanovic, T. , Galbiati, I. , and Haak, N. , 2016, SIGRACET Gas Diffusion Layers for PEM Fuel Cells, Electrolyzers and Batteries, SGL Carbon GmbH, Meitingen, Germany.
Ostadi, H. , Rama, P. , Liu, Y. , Chen, R. , Zhang, X. X. , and Jiang, K. , 2010, “ 3D Reconstruction of a Gas Diffusion Layer and a Microporous Layer,” J. Membr. Sci., 351(1–2), pp. 69–74.
Andisheh-Tadbir, M. , Orfino, F. P. , and Kjeang, E. , 2016, “ Three-Dimensional Phase Segregation of Micro-Porous Layers for Fuel Cells by Nano-Scale X-Ray Computed Tomography,” J. Power Sources, 310, pp. 61–69.
Banerjee, R. , Howe, D. , Mejia, V. , and Kandlikar, S. G. , 2014, “ Experimental Validation of Two-Phase Pressure Drop Multiplier as a Diagnostic Tool for Characterizing PEM Fuel Cell Performance,” Int. J. Hydrogen Energy, 39(31), pp. 17791–17801.
Banerjee, R. , Ge, N. , Lee, J. , George, M. G. , Liu, H. , Muirhead, D. , Shrestha, P. , Chevalier, S. , Hinebaugh, J. , and Bazylak, A. , 2016, “ Determining the Impact of Dynamic Load Conditions on Interfacial Liquid Water Accumulation in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers Using Synchrotron X-Ray Radiography,” ECS Trans., 75(14), pp. 251–259.
Wysokinski, T. W. , Chapman, D. , Adams, G. , Renier, M. , Suortti, P. , and Thomlinson, W. , 2007, “ Beamlines of the Biomedical Imaging and Therapy Facility at the Canadian Light Source—Part 1,” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 582, Elsevier, Amsterdam, The Netherlands, pp. 73–76.
Ge, N. , Chevalier, S. , Hinebaugh, J. , Yip, R. , Lee, J. , Antonacci, P. , Kotaka, T. , Tabuchi, Y. , and Bazylak, A. , 2016, “ Calibrating the X-Ray Attenuation of Liquid Water and Correcting Sample Movement Artefacts During in Operando Synchrotron X-Ray Radiographic Imaging of Polymer Electrolyte Membrane Fuel Cells,” J. Synchrotron Radiat., 23(2), pp. 590–599. [PubMed]
Hinebaugh, J. , Challa, P. R. , and Bazylak, A. , 2012, “ Accounting for Low-Frequency Synchrotron X-Ray Beam Position Fluctuations for Dynamic Visualizations,” J. Synchrotron Radiat., 19(6), pp. 994–1000. [PubMed]
Mason, T. J. , Millichamp, J. , Shearing, P. R. , and Brett, D. J. L. , 2013, “ A Study of the Effect of Compression on the Performance of Polymer Electrolyte Fuel Cells Using Electrochemical Impedance Spectroscopy and Dimensional Change Analysis,” Int. J. Hydrogen Energy, 38(18), pp. 7414–7422.
Sassin, M. B. , Garsany, Y. , Gould, B. D. , and Swider-Lyons, K. , 2016, “ Impact of Compressive Stress on MEA Pore Structure and Its Consequence on PEMFC Performance,” J. Electrochem. Soc., 163(8), pp. F808–F815.
Zhou, Y. , Lin, G. , Shih, A. J. , and Hu, S. J. , 2009, “ Assembly Pressure and Membrane Swelling in PEM Fuel Cells,” J. Power Sources, 192(2), pp. 544–551.
Owejan, J. P. , Trabold, T. A. , and Mench, M. M. , 2014, “ Oxygen Transport Resistance Correlated to Liquid Water Saturation in the Gas Diffusion Layer of PEM Fuel Cells,” Int. J. Heat Mass Transfer, 71, pp. 585–592.
Owejan, J. P. , Gagliardo, J. J. , Sergi, J. M. , Kandlikar, S. G. , and Trabold, T. A. , 2009, “ Water Management Studies in PEM Fuel Cells—Part I: Fuel Cell Design and in Situ Water Distributions,” Int. J. Hydrogen Energy, 34(8), pp. 3436–3444.
Hui, L. , Yanghua, T. , Zhenwei, W. , Zheng, S. , Shaohong, W. , Datong, S. , Jianlu, Z. , Fatih, K. , Jiujun, Z. , Haijiang, W. , Zhongsheng, L. , Abouatallah, R. , and Mazza, A. , 2008, “ A Review of Water Flooding Issues in the Proton Exchange Membrane Fuel Cell,” J. Power Sources, 178(1), pp. 103–17.
Baker, D. R. , Caulk, D. A. , Neyerlin, K. C. , and Murphy, M. W. , 2009, “ Measurement of Oxygen Transport Resistance in PEM Fuel Cells by Limiting Current Methods,” J. Electrochem. Soc., 156(9), pp. B991–B1003.
Owejan, J. P. , Owejan, J. E. , Gu, W. , Trabold, T. A. , Tighe, T. W. , and Mathias, M. F. , 2010, “ Water Transport Mechanisms in PEMFC Gas Diffusion Layers,” J. Electrochem. Soc., 157(10), pp. B1456–B1464.
Weber, A. Z. , and Newman, J. , 2005, “ Effects of Microporous Layers in Polymer Electrolyte Fuel Cells,” J. Electrochem. Soc., 152(4), pp. A677–A688.
Lin, G. , and Nguyen, T. V. , 2006, “ A Two-Dimensional Two-Phase Model of a PEM Fuel Cell,” J. Electrochem. Soc., 153(2), pp. A372–A382.
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## References

Mathias, M. F. , Roth, J. , Fleming, J. , and Lehnert, W. , 2010, “ Diffusion Media Materials and Characterisation,” Handbook of Fuel Cells, Wiley, Chichester, UK. [PubMed] [PubMed]
Cindrella, L. , Kannan, A. M. , Lin, J. F. , Saminathan, K. , Ho, Y. , Lin, C. W. , and Wertz, J. , 2009, “ Gas Diffusion Layer for Proton Exchange Membrane Fuel Cells—A Review,” J. Power Sources, 194(1), pp. 146–160.
Hung, C.-H. , Chiu, C.-H. , Wang, S.-P. , Chiang, I.-L. , and Yang, H. , 2012, “ Ultra Thin Gas Diffusion Layer Development for PEMFC,” Int. J. Hydrogen Energy, 37(17), pp. 12805–12812.
Lee, J. , Chevalier, S. , Banerjee, R. , Antonacci, P. , Ge, N. , Yip, R. , Kotaka, T. , Tabuchi, Y. , and Bazylak, A. , 2017, “ Investigating the Effects of Gas Diffusion Layer Substrate Thickness on Polymer Electrolyte Membrane Fuel Cell Performance Via Synchrotron X-Ray Radiography,” Electrochim. Acta, 236, pp. 161–170.
Göbel, M. , Godehardt, M. , and Schladitz, K. , 2017, “ Multi-Scale Structural Analysis of Gas Diffusion Layers,” J. Power Sources, 355, pp. 8–17.
Park, S. , Lee, J.-W. , and Popov, B. N. , 2012, “ A Review of Gas Diffusion Layer in PEM Fuel Cells: Materials and Designs,” Int. J. Hydrogen Energy, 37(7), pp. 5850–5865.
Banerjee, R. , Hinebaugh, J. , Liu, H. , Yip, R. , Ge, N. , and Bazylak, A. , 2016, “ Heterogeneous Porosity Distributions of Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layer Materials With Rib-Channel Compression,” Int. J. Hydrogen Energy, 41(33), pp. 14885–14896.
Arvay, A. , Yli-Rantala, E. , Liu, C.-H. , Peng, X.-H. , Koski, P. , Cindrella, L. , Kauranen, P. , Wilde, P. M. , and Kannan, A. M. , 2012, “ Characterization Techniques for Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells—A Review,” J. Power Sources, 213, pp. 317–337.
Rofaiel, A. , Ellis, J. S. , Challa, P. R. , and Bazylak, A. , 2012, “ Heterogeneous Through-Plane Distributions of Polytetrafluoroethylene in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers,” J. Power Sources, 201, pp. 219–225.
El-Kharouf, A. , Rees, N. V. , and Steinberger-Wilckens, R. , 2014, “ Gas Diffusion Layer Materials and Their Effect on Polymer Electrolyte Fuel Cell Performance—Ex Situ and In Situ Characterization,” Fuel Cells, 14(5), pp. 735–741.
George, M. , Fishman, Z. , Botelho, S. , and Bazylak, A. , 2016, “ Micro-Computed Tomography-Based Profilometry for Characterizing the Surface Roughness of Microporous Layer-Coated Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers,” J. Electrochem. Soc., 163(8), pp. F832–F841.
Fishman, Z. , Hinebaugh, J. , and Bazylak, A. , 2010, “ Microscale Tomography Investigations of Heterogeneous Porosity Distributions of PEMFC GDLs,” J. Electrochem. Soc., 157(11), pp. B1643–B1650.
Fishman, Z. , and Bazylak, A. , 2011, “ Heterogeneous Through-Plane Distributions of Tortuosity, Effective Diffusivity, and Permeability for PEMFC GDLs,” J. Electrochem. Soc., 158(2), pp. B247–B252.
Fishman, Z. , and Bazylak, A. , 2011, “ Heterogeneous Through-Plane Porosity Distributions for Treated PEMFC GDLs—I: PTFE Effect,” J. Electrochem. Soc., 158(8), pp. B841–B845.
Fishman, Z. , and Bazylak, A. , 2011, “ Heterogeneous Through-Plane Porosity Distributions for Treated PEMFC GDLs—II: Effect of MPL Cracks,” J. Electrochem. Soc., 158(8), pp. B846–B851.
Pfrang, A. , Veyret, D. , Sieker, F. , and Tsotridis, G. , 2010, “ X-Ray Computed Tomography of Gas Diffusion Layers of PEM Fuel Cells: Calculation of Thermal Conductivity,” Int. J. Hydrogen Energy, 35(8), pp. 3751–3757.
Flückiger, R. , Marone, F. , Stampanoni, M. , Wokaun, A. , and Büchi, F. N. , 2011, “ Investigation of Liquid Water in Gas Diffusion Layers of Polymer Electrolyte Fuel Cells Using X-Ray Tomographic Microscopy,” Electrochim. Acta, 56(5), pp. 2254–2262.
Markötter, H. , Manke, I. , Krüger, P. , Arlt, T. , Haussmann, J. , Klages, M. , Riesemeier, H. , Hartnig, C. , Scholta, J. , and Banhart, J. , 2011, “ Investigation of 3D Water Transport Paths in Gas Diffusion Layers by Combined in-Situ Synchrotron X-Ray Radiography and Tomography,” Electrochem. Commun., 13(9), pp. 1001–1004.
Epting, W. K. , Gelb, J. , and Litster, S. , 2012, “ Resolving the Three-Dimensional Microstructure of Polymer Electrolyte Fuel Cell Electrodes Using Nanometer-Scale X-Ray Computed Tomography,” Adv. Funct. Mater., 22(3), pp. 555–560.
James, J. P. , Choi, H.-W. , and Pharoah, J. G. , 2012, “ X-Ray Computed Tomography Reconstruction and Analysis of Polymer Electrolyte Membrane Fuel Cell Porous Transport Layers,” Int. J. Hydrogen Energy, 37(23), pp. 18216–18230.
Wargo, E. A. , Schulz, V. P. , Çeçen, A. , Kalidindi, S. R. , and Kumbur, E. C. , 2013, “ Resolving Macro- and Micro-Porous Layer Interaction in Polymer Electrolyte Fuel Cells Using Focused Ion Beam and X-Ray Computed Tomography,” Electrochim. Acta, 87, pp. 201–212.
Wargo, E. A. , Kotaka, T. , Tabuchi, Y. , and Kumbur, E. C. , 2013, “ Comparison of Focused Ion Beam Versus Nano-Scale X-Ray Computed Tomography for Resolving 3-D Microstructures of Porous Fuel Cell Materials,” J. Power Sources, 241, pp. 608–618.
Lu, Z. , Daino, M. M. , Rath, C. , and Kandlikar, S. G. , 2010, “ Water Management Studies in PEM Fuel Cells—Part III: Dynamic Breakthrough and Intermittent Drainage Characteristics From GDLs With and Without MPLs,” Int. J. Hydrogen Energy, 35(9), pp. 4222–4233.
Lu, Z. , and Patterson, J. , 2013, “ Investigation of Water Breakthrough and Flow in Gas Diffusion Layers and Relavance to Fuel Cell Water Management,” ECS Trans., 50(2), pp. 487–501.
Mortazavi, M. , and Tajiri, K. , 2014, “ Liquid Water Breakthrough Pressure Through Gas Diffusion Layer of Proton Exchange Membrane Fuel Cell,” Int. J. Hydrogen Energy, 39(17), pp. 9409–9419.
Kim, J. , Je, J. , Kim, T. , Kaviany, M. , Son, S. Y. , and Kim, M. , 2012, “ Breakthrough/Drainage Pressures and X-Ray Water Visualization in Gas Diffusion Layer of PEMFC,” Curr. Appl. Phys., 12(1), pp. 105–108.
Flückiger, R. , Freunberger, S. A. , Kramer, D. , Wokaun, A. , Scherer, G. G. , and Büchi, F. N. , 2008, “ Anisotropic, Effective Diffusivity of Porous Gas Diffusion Layer Materials for PEFC,” Electrochim. Acta, 54(2), pp. 551–559.
LaManna, J. M. , and Kandlikar, S. G. , “ Determination of Effective Water Vapor Diffusion Coefficient in PEMFC Gas Diffusion Layers,” Int. J. Hydrogen Energy, 28, pp. 5021–5029.
Hwang, G. S. , and Weber, A. Z. , 2012, “ Effective-Diffusivity Measurement of Partially-Saturated Fuel-Cell Gas-Diffusion Layers,” J. Electrochem. Soc., 159(11), pp. F683–F692.
Gostick, J. T. , Fowler, M. W. , Pritzker, M. D. , Ioannidis, M. A. , and Behra, L. M. , 2006, “ In-Plane and Through-Plane Gas Permeability of Carbon Fiber Electrode Backing Layers,” J. Power Sources, 162(1), pp. 228–238.
Gurau, V. , Bluemle, M. J. , De Castro, E. S. , Tsou, Y.-M. , Zawodzinski, T. A., Jr. , and Mann, J. A., Jr. , 2007, “ Characterization of Transport Properties in Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells—2: Absolute Permeability,” J. Power Sources, 165(2), pp. 793–802.
Sadeghifar, H. , Djilali, N. , and Bahrami, M. , 2014, “ Effect of Polytetrafluoroethylene (PTFE) and Micro Porous Layer (MPL) on Thermal Conductivity of Fuel Cell Gas Diffusion Layers: Modeling and Experiments,” J. Power Sources, 248, pp. 632–641.
Alhazmi, N. , Ismail, M. S. , Ingham, D. B. , Hughes, K. J. , Ma, L. , and Pourkashanian, M. , 2013, “ The In-Plane Thermal Conductivity and the Contact Resistance of the Components of the Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cells,” J. Power Sources, 241, pp. 136–145.
Unsworth, G. , Zamel, N. , and Li, X. , 2012, “ Through-Plane Thermal Conductivity of the Microporous Layer in a Polymer Electrolyte Membrane Fuel Cell,” Int. J. Hydrogen Energy, 37(6), pp. 5161–5169.
Radhakrishnan, A. , Lu, Z. , and Kandlikar, S. G. , 2010, “ Effective Thermal Conductivity of Gas Diffusion Layers Used in PEMFC: Measured With Guarded-Hot-Plate Method and Predicted by a Fractal Model,” ECS Trans., 33(1), pp. 1163–1176.
Khandelwal, M. , and Mench, M. M. , 2006, “ Direct Measurement of Through-Plane Thermal Conductivity and Contact Resistance in Fuel Cell Materials,” J. Power Sources, 161(2), pp. 1106–1115.
Xu, G. , LaManna, J. M. , Clement, J. T. , and Mench, M. M. , 2014, “ Direct Measurement of Through-Plane Thermal Conductivity of Partially Saturated Fuel Cell Diffusion Media,” J. Power Sources, 256, pp. 212–219.
Bazylak, A. , 2009, “ Liquid Water Visualization in PEM Fuel Cells: A Review,” Int. J. Hydrogen Energy, 34(9), pp. 3845–3857.
Kim, S.-G. , and Lee, S.-J. , 2013, “ A Review on Experimental Evaluation of Water Management in a Polymer Electrolyte Fuel Cell Using X-Ray Imaging Technique,” J. Power Sources, 230, pp. 101–108.
Pekula, N. , Heller, K. , Chuang, P. A. , Turhan, A. , Mench, M. M. , Brenizer, J. S. , and Ünlü, K. , 2005, “ Study of Water Distribution and Transport in a Polymer Electrolyte Fuel Cell Using Neutron Imaging,” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 542, Elsevier, Amsterdam, The Netherlands, pp. 134–141.
Boillat, P. , Kramer, D. , Seyfang, B. C. , Frei, G. , Lehmann, E. , Scherer, G. G. , Wokaun, A. , Ichikawa, Y. , Tasaki, Y. , and Shinohara, K. , 2008, “ In Situ Observation of the Water Distribution Across a PEFC Using High Resolution Neutron Radiography,” Electrochem. Commun., 10(4), pp. 546–550.
Hickner, M. A. , Siegel, N. P. , Chen, K. S. , Hussey, D. S. , Jacobson, D. L. , and Arif, M. , 2008, “ In Situ High-Resolution Neutron Radiography of Cross-Sectional Liquid Water Profiles in Proton Exchange Membrane Fuel Cells,” J. Electrochem. Soc., 155(4), pp. B427–B434.
Lu, Z. , Waldecker, J. , Xie, X. , Lai, M.-C. , Hussey, D. S. , and Jacobson, D. L. , 2013, “ Investigation of Water Transport in Perforated Gas Diffusion Layer by Neutron Radiography,” ECS Trans., 58(1), pp. 315–324.
Kotaka, T. , Tabuchi, Y. , Pasaogullari, U. , and Wang, C.-Y. , 2014, “ Impact of Interfacial Water Transport in PEMFCs on Cell Performance,” Electrochim. Acta, 146, pp. 618–629.
Cooper, N. J. , Santamaria, A. D. , Becton, M. K. , and Park, J. W. , “ Neutron Radiography Measurements of in-Situ PEMFC Liquid Water Saturation in 2D & 3D Morphology Gas Diffusion Layers,” Int. J. Hydrogen Energy, 42(25), pp. 169269–16278.
Manke, I. , Hartnig, C. , Grünerbel, M. , Lehnert, W. , Kardjilov, N. , Haibel, A. , Hilger, A. , Banhart, J. , and Riesemeier, H. , 2007, “ Investigation of Water Evolution and Transport in Fuel Cells With High Resolution Synchrotron X-Ray Radiography,” Appl. Phys. Lett., 90(17), p. 174105.
Hinebaugh, J. , Lee, J. , and Bazylak, A. , 2012, “ Visualizing Liquid Water Evolution in a PEM Fuel Cell Using Synchrotron X-Ray Radiography,” J. Electrochem. Soc., 159(12), pp. F826–F830.
Lee, J. , Hinebaugh, J. , and Bazylak, A. , 2013, “ Synchrotron X-Ray Radiographic Investigations of Liquid Water Transport Behavior in a PEMFC With MPL-Coated GDLs,” J. Power Sources, 227, pp. 123–130.
Eller, J. , Roth, J. , Marone, F. , Stampanoni, M. , Wokaun, A. , and Büchi, F. N. , 2011, “ Towards Ultra-Fast X-Ray Tomographic Microscopy of Liquid Water in PEFC,” ECS Trans., 41(1), pp. 387–394.
Eller, J. , Rosén, T. , Marone, F. , Stampanoni, M. , Wokaun, A. , and Büchi, F. N. , 2011, “ Progress in In Situ X-Ray Tomographic Microscopy of Liquid Water in Gas Diffusion Layers of PEFC,” J. Electrochem. Soc., 158(8), pp. B963–B970.
Sasabe, T. , Tsushima, S. , and Hirai, S. , 2010, “ In-Situ Visualization of Liquid Water in an Operating PEMFC by Soft X-Ray Radiography,” Int. J. Hydrogen Energy, 35(20), pp. 11119–11128.
Deevanhxay, P. , Sasabe, T. , Tsushima, S. , and Hirai, S. , 2011, “ Investigation of Water Accumulation and Discharge Behaviors With Variation of Current Density in PEMFC by High-Resolution Soft X-Ray Radiography,” Int. J. Hydrogen Energy, 36(17), pp. 10901–10907.
Haußmann, J. , Markötter, H. , Alink, R. , Bauder, A. , Dittmann, K. , Manke, I. , and Scholta, J. , 2013, “ Synchrotron Radiography and Tomography of Water Transport in Perforated Gas Diffusion Media,” J. Power Sources, 239, pp. 611–622.
Banerjee, R. , Ge, N. , Lee, J. , George, M. G. , Chevalier, S. , Liu, H. , Shrestha, P. , Muirhead, D. , and Bazylak, A. , 2017, “ Transient Liquid Water Distributions in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers Observed Through In-Operando Synchrotron X-Ray Radiography,” J. Electrochem. Soc., 164(2), pp. F154–F162.
Tötzke, C. , Gaiselmann, G. , Osenberg, M. , Bohner, J. , Arlt, T. , Markötter, H. , Hilger, A. , Wieder, F. , Kupsch, A. , Müller, B. R. , Hentschel, M. P. , Banhart, J. , Schmidt, V. , Lehnert, W. , and Manke, I. , 2014, “ Three-Dimensional Study of Compressed Gas Diffusion Layers Using Synchrotron X-Ray Imaging,” J. Power Sources, 253, pp. 123–131.
Dunbar, Z. , and Masel, R. I. , 2007, “ Quantitative MRI Study of Water Distribution During Operation of a PEM Fuel Cell Using Teflon® Flow Fields,” J. Power Sources, 171(2), pp. 678–687.
Minard, K. R. , Viswanathan, V. V. , Majors, P. D. , Wang, L.-Q. , and Rieke, P. C. , 2006, “ Magnetic Resonance Imaging (MRI) of PEM Dehydration and Gas Manifold Flooding During Continuous Fuel Cell Operation,” J. Power Sources, 161(2), pp. 856–863.
Tüber, K. , Pócza, D. , and Hebling, C. , 2003, “ Visualization of Water Buildup in the Cathode of a Transparent PEM Fuel Cell,” J. Power Sources, 124(2), pp. 403–414.
Hussaini, I. S. , and Wang, C.-Y. , 2009, “ Visualization and Quantification of Cathode Channel Flooding in PEM Fuel Cells,” J. Power Sources, 187(2), pp. 444–451.
Sergi, J. M. , Lu, Z. , and Kandlikar, S. G. , 2009, “ In Situ Characterization of Two-Phase Flow in Cathode Channels of an Operating PEM Fuel Cell With Visual Access,” ASME Paper No. ICNMM2009-82140.
Sergi, J. M. , and Kandlikar, S. G. , 2011, “ Quantification and Characterization of Water Coverage in PEMFC Gas Channels Using Simultaneous Anode and Cathode Visualization and Image Processing,” Int. J. Hydrogen Energy, 36(19), pp. 12381–12392.
Banerjee, R. , and Kandlikar, S. G. , 2014, “ Liquid Water Quantification in the Cathode Side Gas Channels of a Proton Exchange Membrane Fuel Cell Through Two-Phase Flow Visualization,” J. Power Sources, 247, pp. 9–19.
Escribano, S. , Blachot, J.-F. , Ethève, J. , Morin, A. , and Mosdale, R. , 2006, “ Characterization of PEMFCs Gas Diffusion Layers Properties,” J. Power Sources, 156(1), pp. 8–13.
Chevalier, S. , Ge, N. , George, M. G. , Lee, J. , Banerjee, R. , Liu, H. , Shrestha, P. , Muirhead, D. , Hinebaugh, J. , Tabuchi, Y. , Kotaka, T. , and Bazylak, A. , 2017, “ Synchrotron X-Ray Radiography as a Highly Precise and Accurate Method for Measuring the Spatial Distribution of Liquid Water in Operating Polymer Electrolyte Membrane Fuel Cells,” J. Electrochem. Soc., 164(2), pp. F107–F114.
Sasabe, T. , Deevanhxay, P. , Tsushima, S. , and Hirai, S. , 2011, “ Soft X-Ray Visualization of the Liquid Water Transport Within the Cracks of Micro Porous Layer in PEMFC,” Electrochem. Commun., 13(6), pp. 638–641.
Deevanhxay, P. , Sasabe, T. , Tsushima, S. , and Hirai, S. , 2013, “ Observation of Dynamic Liquid Water Transport in the Microporous Layer and Gas Diffusion Layer of an Operating PEM Fuel Cell by High-Resolution Soft X-Ray Radiography,” J. Power Sources, 230, pp. 38–43.
Markötter, H. , Haußmann, J. , Alink, R. , Tötzke, C. , Arlt, T. , Klages, M. , Riesemeier, H. , Scholta, J. , Gerteisen, D. , Banhart, J. , and Manke, I. , 2013, “ Influence of Cracks in the Microporous Layer on the Water Distribution in a PEM Fuel Cell Investigated by Synchrotron Radiography,” Electrochem. Commun., 34, pp. 22–24.
Ge, N. , Chevalier, S. , Lee, J. , Yip, R. , Banerjee, R. , George, M. G. , Liu, H. , Lee, C. , Fazeli, M. , Antonacci, P. , Kotaka, T. , Tabuchi, Y. , and Bazylak, A. , 2017, “ Non-Isothermal Two-Phase Transport in a Polymer Electrolyte Membrane Fuel Cell With Crack-Free Microporous Layers,” Int. J. Heat Mass Transfer, 107, pp. 418–431.
Antonacci, P. , Chevalier, S. , Lee, J. , Ge, N. , Hinebaugh, J. , Yip, R. , Tabuchi, Y. , Kotaka, T. , and Bazylak, A. , 2016, “ Balancing Mass Transport Resistance and Membrane Resistance When Tailoring Microporous Layer Thickness for Polymer Electrolyte Membrane Fuel Cells Operating at High Current Densities,” Electrochim. Acta, 188, pp. 888–897.
Lee, J. , Yip, R. , Antonacci, P. , Ge, N. , Kotaka, T. , Tabuchi, Y. , and Bazylak, A. , 2015, “ Synchrotron Investigation of Microporous Layer Thickness on Liquid Water Distribution in a PEM Fuel Cell,” J. Electrochem. Soc., 162(7), pp. F669–F676.
Zenyuk, I. V. , Parkinson, D. Y. , Hwang, G. , and Weber, A. Z. , 2015, “ Probing Water Distribution in Compressed Fuel-Cell Gas-Diffusion Layers Using X-Ray Computed Tomography,” Electrochem. Commun., 53, pp. 24–28.
Eller, J. , and Büchi, F. N. , 2016, “ Characterization of Water Cluster Connectivity and Fluid Transport in PEFC Gas Diffusion Layers,” Meet. Abstr., MA2016-02(38), p. 2494.
Eller, J. , 2013, “ X-Ray Tomographic Microscopy of Polymer Electrolyte Fuel Cells,” Ph.D. thesis, ETH Zürich, Zürich, Switzerland.
Hinebaugh, J. , Lee, J. , Mascarenhas, C. , and Bazylak, A. , 2015, “ Quantifying Percolation Events in PEM Fuel Cell Using Synchrotron Radiography,” Electrochim. Acta, 184, pp. 417–426.
Muirhead, D. , Banerjee, R. , Lee, J. , George, M. G. , Ge, N. , Liu, H. , Chevalier, S. , Hinebaugh, J. , and Bazylak, A. , 2017, “ Simultaneous Characterization of Oxygen Transport Resistance and Spatially Resolved Liquid Water Saturation at High-Current Density of Polymer Electrolyte Membrane Fuel Cells With Varied Cathode Relative Humidity,” Int. J. Hydrogen Energy (Submitted).
Liu, H. , George, M. G. , Banerjee, R. , Ge, N. , Lee, J. , Muirhead, D. , Shrestha, P. , Chevalier, S. , Hinebaugh, J. , Zeis, R. , Messerschmidt, M. , Scholta, J. , and Bazylak, A. , 2017, “ Accelerated Degradation of Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers—Part 2: Steady State Liquid Water Distributions With in Operando Synchrotron X-Ray Radiography,” J. Electrochem. Soc., 164, pp. F704–F713.
Schweiss, R. , Meiser, C. , Damjanovic, T. , Galbiati, I. , and Haak, N. , 2016, SIGRACET Gas Diffusion Layers for PEM Fuel Cells, Electrolyzers and Batteries, SGL Carbon GmbH, Meitingen, Germany.
Ostadi, H. , Rama, P. , Liu, Y. , Chen, R. , Zhang, X. X. , and Jiang, K. , 2010, “ 3D Reconstruction of a Gas Diffusion Layer and a Microporous Layer,” J. Membr. Sci., 351(1–2), pp. 69–74.
Andisheh-Tadbir, M. , Orfino, F. P. , and Kjeang, E. , 2016, “ Three-Dimensional Phase Segregation of Micro-Porous Layers for Fuel Cells by Nano-Scale X-Ray Computed Tomography,” J. Power Sources, 310, pp. 61–69.
Banerjee, R. , Howe, D. , Mejia, V. , and Kandlikar, S. G. , 2014, “ Experimental Validation of Two-Phase Pressure Drop Multiplier as a Diagnostic Tool for Characterizing PEM Fuel Cell Performance,” Int. J. Hydrogen Energy, 39(31), pp. 17791–17801.
Banerjee, R. , Ge, N. , Lee, J. , George, M. G. , Liu, H. , Muirhead, D. , Shrestha, P. , Chevalier, S. , Hinebaugh, J. , and Bazylak, A. , 2016, “ Determining the Impact of Dynamic Load Conditions on Interfacial Liquid Water Accumulation in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers Using Synchrotron X-Ray Radiography,” ECS Trans., 75(14), pp. 251–259.
Wysokinski, T. W. , Chapman, D. , Adams, G. , Renier, M. , Suortti, P. , and Thomlinson, W. , 2007, “ Beamlines of the Biomedical Imaging and Therapy Facility at the Canadian Light Source—Part 1,” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 582, Elsevier, Amsterdam, The Netherlands, pp. 73–76.
Ge, N. , Chevalier, S. , Hinebaugh, J. , Yip, R. , Lee, J. , Antonacci, P. , Kotaka, T. , Tabuchi, Y. , and Bazylak, A. , 2016, “ Calibrating the X-Ray Attenuation of Liquid Water and Correcting Sample Movement Artefacts During in Operando Synchrotron X-Ray Radiographic Imaging of Polymer Electrolyte Membrane Fuel Cells,” J. Synchrotron Radiat., 23(2), pp. 590–599. [PubMed]
Hinebaugh, J. , Challa, P. R. , and Bazylak, A. , 2012, “ Accounting for Low-Frequency Synchrotron X-Ray Beam Position Fluctuations for Dynamic Visualizations,” J. Synchrotron Radiat., 19(6), pp. 994–1000. [PubMed]
Mason, T. J. , Millichamp, J. , Shearing, P. R. , and Brett, D. J. L. , 2013, “ A Study of the Effect of Compression on the Performance of Polymer Electrolyte Fuel Cells Using Electrochemical Impedance Spectroscopy and Dimensional Change Analysis,” Int. J. Hydrogen Energy, 38(18), pp. 7414–7422.
Sassin, M. B. , Garsany, Y. , Gould, B. D. , and Swider-Lyons, K. , 2016, “ Impact of Compressive Stress on MEA Pore Structure and Its Consequence on PEMFC Performance,” J. Electrochem. Soc., 163(8), pp. F808–F815.
Zhou, Y. , Lin, G. , Shih, A. J. , and Hu, S. J. , 2009, “ Assembly Pressure and Membrane Swelling in PEM Fuel Cells,” J. Power Sources, 192(2), pp. 544–551.
Owejan, J. P. , Trabold, T. A. , and Mench, M. M. , 2014, “ Oxygen Transport Resistance Correlated to Liquid Water Saturation in the Gas Diffusion Layer of PEM Fuel Cells,” Int. J. Heat Mass Transfer, 71, pp. 585–592.
Owejan, J. P. , Gagliardo, J. J. , Sergi, J. M. , Kandlikar, S. G. , and Trabold, T. A. , 2009, “ Water Management Studies in PEM Fuel Cells—Part I: Fuel Cell Design and in Situ Water Distributions,” Int. J. Hydrogen Energy, 34(8), pp. 3436–3444.
Hui, L. , Yanghua, T. , Zhenwei, W. , Zheng, S. , Shaohong, W. , Datong, S. , Jianlu, Z. , Fatih, K. , Jiujun, Z. , Haijiang, W. , Zhongsheng, L. , Abouatallah, R. , and Mazza, A. , 2008, “ A Review of Water Flooding Issues in the Proton Exchange Membrane Fuel Cell,” J. Power Sources, 178(1), pp. 103–17.
Baker, D. R. , Caulk, D. A. , Neyerlin, K. C. , and Murphy, M. W. , 2009, “ Measurement of Oxygen Transport Resistance in PEM Fuel Cells by Limiting Current Methods,” J. Electrochem. Soc., 156(9), pp. B991–B1003.
Owejan, J. P. , Owejan, J. E. , Gu, W. , Trabold, T. A. , Tighe, T. W. , and Mathias, M. F. , 2010, “ Water Transport Mechanisms in PEMFC Gas Diffusion Layers,” J. Electrochem. Soc., 157(10), pp. B1456–B1464.
Weber, A. Z. , and Newman, J. , 2005, “ Effects of Microporous Layers in Polymer Electrolyte Fuel Cells,” J. Electrochem. Soc., 152(4), pp. A677–A688.
Lin, G. , and Nguyen, T. V. , 2006, “ A Two-Dimensional Two-Phase Model of a PEM Fuel Cell,” J. Electrochem. Soc., 153(2), pp. A372–A382.

## Figures

Fig. 4

Schematic of the imaging setup for the fuel cell. The scale bar on the radiograph is 1 mm long.

Fig. 3

Cross-sectional slices of the GDL in the in-plane and through-plane directions for (a) SGL 10 BA, (b) SGL 10 BC, (c) SGL 25 BA, and (d) SGL 25 BC. Black represents fiber, orange represents MPL, and white is void space. Please see online figures for references to color.

Fig. 2

Example porosity profile of SGL 10 BC, showing the individual solid fraction for the carbon fiber and MPL phases

Fig. 1

Schematic of X-ray CT setup

Fig. 5

Profiles for the solid fractions of (a) uncompressed GDL, and (b) compressed GDL. The void space above the solid fractions represents the porous region of the GDL. The x = 0 μm through-plane position corresponds to the outer surface of the GDL. The first solid fraction value shown (where x > 0 μm) corresponds to the half-width location of the first voxel.

Fig. 6

Normalized water thickness measured in GDL regions through X-ray radiography during fuel cell operation: (a) SGL 10 BA—channel, (b) SGL 25 BA—channel, (c) SGL 10 BA—land, and (d) SGL 25 BA—Land. Shaded region indicates position of the membrane.

Fig. 7

Normalized water thickness measured from X-ray radiography during fuel cell operation: (a) SGL 10 BC—channel, (b) SGL 25 BC—channel, (c) SGL 10 BC—land, and (d) SGL 25 BC—land. Shaded region indicates position of the membrane.

## Tables

Table 1 Description of properties for each GDL investigated in this study
aSpecification sheet.
bWhite paper from SGL [77].
cDefined in Sec. 2.2.
dExperimental condition, as specified in Sec. 2.3.
Table 2 MPL thickness and MPL intrusion for bilayered GDLs

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