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Ji, Sheng Zheng, Zhuang Song und Ying He. „Study on Diffusion Characteristics of Liquid Water in Gas Diffusion Layer by Lattice Boltzmann Method“. International Journal of Engineering Research in Africa 71 (18.09.2024): 1–16. http://dx.doi.org/10.4028/p-3yl8ms.
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The gas diffusion layer (GDL) is a crucial component of Proton Exchange Membrane Fuel Cells (PEMFC), water flooding will occur during the operation of PEMFC, resulting in performance degradation, and its water management plays a significant role in PEMFC performance. To investigate the transport mechanism of liquid water in GDL, the lattice Boltzmann method to simulate the behavior of GDL droplets using the 'random reconstruction' method. The accuracy of this model by calculating the tortuosity and comparing it with reported results in literature. The effects of different GDL structural parameters on permeability were studied. Finally, the conductivity and thermal conductivity of the GDL in various directions were examined. The results indicate that the porosity error of the three-dimensional structure model of GDL is within 0.01, enabling a realistic simulation of the GDL structure. The average error between the calculated results and the Bruggeman equation is only 2.5362%, and the average error compared to the reference results is less than 6%, demonstrating the model's high accuracy. As the porosity and fiber diameter of the GDL three-dimensional structure model increase, the permeability also increases. Conversely, the permeability decreases with an increase in the thickness of the GDL three-dimensional structure model. Moreover, an increase in GDL porosity leads to a gradual decrease in electrical conductivity and thermal conductivity in both the thickness and plane directions, with a more pronounced effect on the thickness. This study uncovers the transport characteristics of liquid water in the gas diffusion layer, which can inform the optimization of GDL structure design and serve as a theoretical reference for enhancing water management in proton exchange membrane fuel cells. Future research directions will focus on further optimizing the three-dimensional structure of GDL to improve its transmission characteristics and overall performance.
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Alishahi, Marzieh, Claire McCague und Majid Bahrami. „Evaluation of Porous Media Gas Diffusion Models for PEMFC Applications“. ECS Meeting Abstracts MA2022-01, Nr. 39 (07.07.2022): 1762. http://dx.doi.org/10.1149/ma2022-01391762mtgabs.
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Abstract. Polymer electrolyte membrane fuel cells (PEMFCs) are considered as zero emission power sources for transportation and stationary power purposes. The membrane electrode assembly (MEA) is the core of PEMFC and is composed of a gas diffusion layer (GDL), catalyst layer (CL) and proton exchange membrane (PEM). GDL is a carbon-based, fibrous porous medium that simultaneously provides a path for heat, mass and electron transport, as well as providing a mechanically robust support for the CL. The gas diffusion in the GDL can be estimated by Fick’s law where the effective diffusion coefficient of gaseous species is used. There are many models in the literature based on correlations defining the effective diffusion coefficients through GDLs. Some of these models were originally derived to estimate the transport properties of a porous media composed of spherical particles, e.g. Bruggeman approximation and effective medium approximation. Inherently, such models tend to result to more inaccurate outcomes compared to the models which assume the GDL structure as cylindrical carbon fibers, i.e. the diffusion model based on percolation theory. The percolation theory model considers GDL as a medium composed of freely overlapping fibers oriented in different directions. However, there are several models available in the literature with less simplifying assumptions in GDL structure. The pore network model (PNM) reconstruct the porous media using topology and size information extracted from high resolution tomographic patterns. Also CFD based models can even investigate the actual GDL structure and reconstruct the 3D stochastic porous medium microstructure. These models combine pore-scale model with CFD approaches, e.g. lattice Boltzmann method (LBM) or direct numerical simulation (DNS). This study compares the available models for dry gas diffusion in GDL with experimental data acquired from symmetrical modified Loschmidt cell (SMLC). The SMLC is employed to measure the effective diffusion coefficient of oxygen passing through GDL samples, i.e. SGL SIGRACET 24BA, 24 BC, 25BA, 25BC and TGP-H-060. The SMLC result for effective diffusion coefficient in TGP-H-060 has less than 2% difference with the available data in the literature for this type of GDL. In order to evaluate the accuracy of effective medium models and percolation theory model, the experimental data for the above-mentioned GDLs is compared with the predictions of these models. The porosity of GDL samples are in the valid range of diffusion models. The diffusion models based on the effective medium approximation have the greater difference with SMLC data in compare with the percolation theory model. The model’s predictions are the worst for the GDLs with microporous layer (MPL), i.e. SIGRACET 24 BC and 25BC. Since the MPL imposes an extra resistance to gas diffusion which is not considered in any GDL diffusion models. The least error in model’s outcome is 30% which associates to the effective diffusion coefficient predicted by percolation theory model for SIGRACET 25BA.
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Ringström, Marcus, Rakel Wreland Lindström, Göran Lindbergh und Henrik Ekström. „Experimental Characterization of Anisotropic Mechanical and Thermal Properties of Gas Diffusion Layers“. ECS Meeting Abstracts MA2022-01, Nr. 37 (07.07.2022): 1645. http://dx.doi.org/10.1149/ma2022-01371645mtgabs.
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Gas diffusion layer (GDL) is a vital component in proton exchange membrane fuel cells (PEMFC) due its main functions to conduct electrons and heat between the adjacent fuel cell components, provide preferential pathways for product water removal and to provide uniform reactant gas flow distribution to the electrode surface. Because of the anisotropic GDL microstructure, the transport properties vary in the through-plane and in-plane direction. Furthermore, during fuel cell stack assembly pressures exerted on the flowfield land compress the GDL under land cause changes of the GDL microstructure. While moderate compression increases GDL thermal conductivity due to increased fiber-fiber contacts, excessive compression may impede diffusive and liquid water transport due to loss of GDL pore volume. Detailed knowledge of how thermal conductivity is affected by the anisotropic nature of gas diffusion layers under compression is imperative in order to provide a better understanding on how thermal gradients influence two-phase transport during PEMFC operation. Previous research efforts have focused on steady-state methods for measuring effective through-plane GDL thermal conductivity [1][2][3][4] and effective in-plane GDL thermal conductivity [5][6] but to the best of our knowledge no studies have been conducted to measure effective in-plane GDL thermal conductivity for a variety of different GDL types under compression. This study attempts to fill that gap by using specially designed in-house tools to characterize the influence of GDL anisotropy on effective thermal conductivity as a function compression for different GDL types. Furthermore, a comprehensive ex-situ mechanical study is conducted to characterize the compliance matrix for different GDL types. Early results indicate a highly non-linear compressive behaviour in the GDL through-plane direction with large variations for the different GDL types. Moreover, the flexural modulus is found to be highly anisotropic where stiffness in the GDL machine direction (MD) is consistently larger compared to stiffness in GDL cross machine direction (CMD). This work will provide a foundation for a numerical study to couple an anisotropic GDL structural model with a non-isothermal two-phase model to investigate the effects of inhomogenous compression on two-phase transport. Keywords: GDL, PEMFC, ex-situ, anisotropy, modulus, microstructure, mechanical, compression, characterization, MD, CMD, through-plane, in-plane, thermal conductivity [1] G. Karimi, X. Li, P. Teertstra, Electrochim. Acta (2010). [2] R. Bock, A.D. Shum, X. Xiao, H. Karoliussen, F. Seland, I. V. Zenyuk, O.S. Burheim, J. Electrochem. Soc. 165 (2018) F514–F525. [3] G. Unsworth, N. Zamel, X. Li, Int. J. Hydrogen Energy (2012). [4] E. Sadeghi, N. Djilali, M. Bahrami, J. Power Sources (2011). [5] E. Sadeghi, N. Djilali, M. Bahrami, J. Power Sources (2011). [6] N. Alhazmi, D.B. Ingham, M.S. Ismail, K.J. Hughes, L. Ma, M. Pourkashanian, Int. J. Hydrogen Energy (2013).
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Berger, Anne, Yen-Chun Chen, Jacqueline Gatzemeier, Felix N. Buechi und Hubert Andreas Gasteiger. „Importance of Directed Water Removal: Intruding Microporous Layer Material into the Gas Diffusion Layer Substrate“. ECS Meeting Abstracts MA2023-02, Nr. 37 (22.12.2023): 1766. http://dx.doi.org/10.1149/ma2023-02371766mtgabs.
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Proton exchange membrane fuel cells (PEMFC) are an essential component of net zero emission scenarios by the International Energy Agency (IEA), most prominent in the heavy-duty transportation sector.[1-2] During operation, the PEMFC is subject to different operating conditions, particularly wet conditions where liquid water removal is crucial. It was observed that a microporous layer (MPL), commonly consisting of a carbon component (e.g. carbon black, carbon fibers) and a hydrophobic binder (e.g. PTFE), placed at the interface of the catalyst layer (CL) and the gas diffusion layer substrate (GDL-S), has a large impact on the water removal properties. Among other advantages, the addition of an MPL can guide the localization of water clusters in the GDL.[3] However, if interfaces exhibit large interfacial gaps, as was demonstrated for the CL/MPL interface,[4] liquid water can accumulate in the large openings, thereby creating a mass transport barrier. Seeking to understand the importance of interfaces, which can either guide water formation or create obstacles, this study further investigates the MPL/GDL-S interface. We created an intruding MPL by pressing the MPL slurry into the GDL-S using mechanical force (further on referred to as “intruded-GDL”) and compared it to a GDL, where the MPL sits quasi on top (further on referred to as “sheet-GDL”). Figure 1a shows a cross-sectional scanning electron microscopy (SEM image) of the sheet-GDL, while Figure 1b shows an intruded-GDL. The boundaries between the MPL material and the GDL-S are marked in red. The MPL/GDL-S interface of the sheet-GDL is relatively flat, following only the surface contour of the GDL-S, while the MPL/GDL-S interface of the intruded-GDL is pressed into the GDL-S and locally penetrates deeper into the GDL-S. It is also visible that the penetration into the GDL-S is inhomogeneous. We characterized the altered morphology using SEM (see Figure 1), mercury intrusion porosimetry (MIP), and x-ray tomographic microscopy (XTM). We found that the MPL of the intruded-MPL intrudes significantly into the GDL-S and preferably fills the larger pores of the GDL-S. Both types of GDLs were subject to single-cell fuel cell testing under various operating conditions. We found that the intruding MPL poses an additional oxygen transport resistance at dry conditions compared to the sheet-GDL. Under conditions where liquid water formation can be expected, the intruded-GDL starts to have an advantage compared to the sheet-GDL. From the data obtained in this study, a delicate interplay between the additional dry transport resistance, the missing macropores that were filled with MPL material, and the guided water removal properties can be deduced. We can derive an improved water removal mechanism for the intruded-GDL as a cause of the structural changes, which can serve as a guideline to improve GDL design parameters. References [1] IEA, Net Zero by 2050 2021,https://www.iea.org/reports/net-zero-by-2050. [2] D. A. Cullen, K. C. Neyerlin, R. K. Ahluwalia, R. Mukundan, K. L. More, R. L. Borup, A. Z. Weber, D. J. Myers, A. Kusoglu, Nat. Energy 2021, 6, 462-474. [3] J. T. Gostick, M. A. Ioannidis, M. W. Fowler, M. D. Pritzker, Electrochem. commun. 2009, 11, 576-579. [4] I. V. Zenyuk, E. C. Kumbur, S. Litster, J. Power Sources 2013, 241, 379-387. Acknowledgements We gratefully acknowledge funding from the Swiss National Science Foundation under the Sinergia grant number 180335. Figure 1 . SEM cross-sectional images different GDL configurations: a) a sheet-GDL; b) an intruded-GDL. The contours of the MPL material is marked with red lines. The MPL of the sheet-GDL is situated on top of the GDL-S, following the GDL-S surface contour, while the MPL of the intruded-GDL intrudes into larger pores of the GDL-S in an inhomogeneous manner. Figure 1
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Yang, Mingyang, Aimin Du, Jinling Liu und Sichuan Xu. „Lattice Boltzmann Method Study on Liquid Water Dynamic inside Gas Diffusion Layer with Porosity Distribution“. World Electric Vehicle Journal 12, Nr. 3 (25.08.2021): 133. http://dx.doi.org/10.3390/wevj12030133.
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The gas diffusion layer (GDL) plays an important role in the mass transfer process during proton exchange membrane fuel cell (PEMFC) operation. However, the GDL porosity distribution, which has often been ignored in the previous works, influences the mass transfer significantly. In this paper, a 2D lattice Boltzmann method model is employed to simulate the liquid water transport process in the real GDL (considered porosity distribution) and the ideal GDL (ignore porous distribution), respectively. It was found that the liquid water transport in the real GDL will be significantly affected by the local low porosity area. In the real GDL, a liquid water saturation threshold can be noticed when the contact angle is about 118°. The GDL porosity distribution shows a stronger influence on liquid dynamic than hydrophobicity, which needs to be considered in future GDL modelling and design.
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Yilmaz, Abdurrahman, Siddharth Komini Babu, Ugur Pasaogullari, Jacob S. Spendelow und Rangachary Mukundan. „Optimization of the Cathode Gas Diffusion Layer Also Matters for Water Electrolyzers“. ECS Meeting Abstracts MA2022-02, Nr. 40 (09.10.2022): 1491. http://dx.doi.org/10.1149/ma2022-02401491mtgabs.
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Polymer electrolyte water electrolyzers (PEMWEs) are a promising technology for the storage of energy from intermittent renewable sources such as wind and solar. PEMWEs split water into hydrogen and oxygen electrochemically. Under typical operating conditions, the hydrogen evolution reaction (HER) in the cathode is not limited by reactant transport, since it is supplied by the rapid transport of protons from the polymer electrolyte and electrons from the external circuit. There are very limited studies on the role of the cathode gas diffusion layer (GDL), typically a carbon-paper based layer. In this study, we investigated the effect of thickness, presence of a microporous layer, and wettability of the cathode GDL. Results show that cathode GDL properties have a significant effect on the performance of the PEMWE cells. Figure 1a shows the importance of the GDL thickness with the optimized GDL compression. The thickest GDL, MGL370 (i.e. 370µm thick ) has the best performance compared to MGL280 (280µm thick) and MGL190 (190µm thick). Compression of the GDL also affects the performance: when the compression is increased from 12% to 25% of the thickness, a performance loss is observed possibly due to damaged carbon fiber network and collapse the pores of the GDL (Figure 1b). Acknowledgment: Financial support from the US Department of Energy through the Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cells Technology Office is gratefully acknowledged. Figure 1
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Yoshikawa, Makoto, Kotaro Yamamoto, Zhiyun Noda, Masahiro Yasutake, Tatsumi Kitahara, Yuya Tachikawa, Stephen Matthew Lyth, Akari Hayashi, Junko Matsuda und Kazunari Sasaki. „Self-Supporting Microporous Layer for Polymer Electrolyte Fuel Cells“. ECS Transactions 112, Nr. 4 (29.09.2023): 83–91. http://dx.doi.org/10.1149/11204.0083ecst.
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The gas diffusion layer (GDL) used in a PEFC is thicker than the electrode catalyst layer and electrolyte membrane. Thinning down the GDL can reduce gas diffusion resistance and volumetric power density of PEFC stacks. In this study, MPL/GDL is prepared by printing microporous layers (MPLs) on carbon meshes of several tens of micrometers thick as substrates for thin-layer GDLs. Through various current-voltage and overvoltage measurements and microstructural analysis of the cells using these thin-layer MPL/GDLs, cell performance has been improved, equivalent to that of the state of the MPL/GDL.
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Jung, Sung Yong, Jooyoung Park, Hanwook Park, Hwanyeong Oh und Jong Woon Moon. „Degradation Effect of Gas Diffusion Layer on Water Transport in Polymer Electrolyte Membrane Fuel Cell“. ECS Meeting Abstracts MA2022-01, Nr. 41 (07.07.2022): 2426. http://dx.doi.org/10.1149/ma2022-01412426mtgabs.
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Hydrogen is converted to electric power by proton exchange membrane fuel cells (PEMFCs), which have received significant attention for transportation applications because of their high energy efficiency. In order to ensure the long-term stability, understanding about their long-term durability is essential because the operating performance deteriorates over time. Gas diffusion layers (GDLs) manage the transport of water generated from the CL during chemical reactions, and the degradation of the GDL significantly deteriorate the fuel cell performance. Compared to the fresh GDL, the water transport characteristics of GDL aged by inserting hydrogen peroxide solutions are investigated. The dynamic movement of the water meniscus inside the GDL is visualized using synchrotron X-ray imaging. Unlike the pristine GDL having snap-off patterns, water continuously transports through the degraded GDL representing the piston-like movement, and pressure fluctuations are not observed. This difference shows the change of the dominant local transport mechanisms due to GDL degradation. The temporal pressure variations are simultaneously measured, and the pressure and time at breakthrough (BT) are compared. The aged GDL exhibits a larger BT pressure and requires a longer time to achieve the first BT. Longer BT time in the degraded GDL can reflect a higher water saturation level. GDL degradation leads to the loss of polytetrafluoroethylene (PTFE) which is commonly treated to ensure efficient mass transport by restraining water clogging in the GDL pores due to the increase of hydrophobicity. Despite the reduction in hydrophobicity, The PTFE loss can increase BT pressure by reducing the pore size and the actual path length of the water flow. The increase in the BT time and BT pressure, as well as continuous transport, can disrupt fuel supply to chemical reaction sites, thereby deteriorating the PEMFC performance. This study provides a comprehensive understanding of the effect of GDL degradation on mass transport in PEMFCs. Figure 1
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Truong, Van Men, Ngoc Bich Duong und Hsiharng Yang. „Effect of Gas Diffusion Layer Thickness on the Performance of Anion Exchange Membrane Fuel Cells“. Processes 9, Nr. 4 (19.04.2021): 718. http://dx.doi.org/10.3390/pr9040718.
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Gas diffusion layers (GDLs) play a critical role in anion exchange membrane fuel cell (AEMFC) water management. In this work, the effect of GDL thickness on the cell performance of the AEMFC was experimentally investigated. Three GDLs with different thicknesses of 120, 260, and 310 µm (denoted as GDL-120, GDL-260, and GDL-310, respectively) were prepared and tested in a single H2/O2 AEMFC. The experimental results showed that the GDL-260 employed in both anode and cathode electrodes exhibited the best cell performance. There was a small difference in cell performance for GDL-260 and GDL-310, while water flooding was observed in the case of using GDL-120 operated at current densities greater than 1100 mA cm−2. In addition, it was found that the GDL thickness had more sensitivity to the AEMFC performance as used in the anode electrode rather than in the cathode electrode, indicating that water removal at the anode was more challenging than water supply at the cathode. The strategy of water management in the anode should be different from that in the cathode. These findings can provide a further understanding of the role of GDLs in the water management of AEMFCs.
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Syarif, Nirwan, Dedi Rohendi, Ade Dwi Nanda, M. Try Sandi und Delima Sukma Wati Br Sihombing. „Gas diffusion layer from Binchotan carbon and its electrochemical properties for supporting electrocatalyst in fuel cell“. AIMS Energy 10, Nr. 2 (2022): 292–305. http://dx.doi.org/10.3934/energy.2022016.
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<abstract> <p>The gas diffusion layer (GDL) in the fuel cell has been made from carbon dispersion electrochemically deposited from binchotan. We prepared GDL by spraying the ink on the surface of the conductive paper. The carbon was then characterized by its crystallography, surface functional groups and size by x-ray diffraction (XRD), FT-IR and PSA instrumentations. Cyclic voltammetry and impedance spectroscopy tests were applied to study the GDL electrochemical characters. Buble drop tests were used to obtain contact angles representing the hydrophobicity of the layer. The electrodeposition/oxidation of binchotan derived carbon dispersion has a crystalline phase in its dot structure. According to particle size analysis, carbon dispersion has an average particle size diameter of 176.7 nm, a range of 64.5–655.8 nm, and a polydispersity index was 0.138. The Nyquist plot revealed that the processes in the GDL matrices as the plot consist of two types of structures, i.e., semicircular curves and vertical (sloping) lines. The GDL electrical conductivity of Vulcan and carbon dots were 0.053 and 0.039 mho cm<sup>-1</sup>. The contact angle between conductive paper and water was 150.27°; between the gas diffusion layer and carbon Vulcan was 123.28°, and between the gas diffusion layer and carbon dispersion was 95.31°. The surface of the GDL with Vulcan is more hydrophobic than that made with carbon dispersion. In other words, the GDL with carbon dispersion is closer to hydrophilic properties. The results show that the carbon can support the gas diffusion layer for hydrophobic and hydrophilic conditions.</p> </abstract>
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Qitong, Shi, Qianqian Wang, Feng Cong und Pingwen Ming. „(Digital Presentation) A Constant Deformation Modulus for the Simulation of Gas Diffusion Layer“. ECS Meeting Abstracts MA2022-01, Nr. 41 (07.07.2022): 2385. http://dx.doi.org/10.1149/ma2022-01412385mtgabs.
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The deformation of gas diffusion layer(GDL) directly affects gas diffusion and electron transfer in the fuel cell. The modulus of stress-strain relationship is the basic parameter in the process of deformation. In this paper, based on beam bending theory and geometric probability analysis, a nonlinear analytic model of stress-strain with physical meaning is established, and a constant deformation modulus of GDL is given. Based on the deformation modulus, we further simulate the inhomogeneous deformation of GDL within a half channel-rib model. The results indicate that the uneven deformation with deformation modulus is more significant than that with linear elastic modulus in the same condition. Finally, a shape-dependent bending radius design for the rib edge is proposed, in which the inhomogeneous deformation of GDL becomes smoother as the radius increases, thereby improving the service condition of GDL and prolonging its service life.
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Qitong, Shi, Feng Cong und Pingwen Ming. „(Digital Presentation) A Constant Deformation Modulus for the Simulation of Gas Diffusion Layer“. ECS Meeting Abstracts MA2022-02, Nr. 40 (09.10.2022): 1494. http://dx.doi.org/10.1149/ma2022-02401494mtgabs.
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The deformation of gas diffusion layer(GDL) directly affects gas diffusion and electron transfer in the fuel cell. The modulus of stress-strain relationship is the basic parameter in the process of deformation. In this paper, based on beam bending theory and geometric probability analysis, a nonlinear analytic model of stress-strain with physical meaning is established, and a constant deformation modulus of GDL is given. Based on the deformation modulus, we further simulate the inhomogeneous deformation of GDL within a half channel-rib model. The results indicate that the uneven deformation with deformation modulus is more significant than that with linear elastic modulus in the same condition. Finally, a shape-dependent bending radius design for the rib edge is proposed, in which the inhomogeneous deformation of GDL becomes smoother as the radius increases, thereby improving the service condition of GDL and prolonging its service life.
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Atifi, A., K. El Bikri und M. Ettouhami. „Numerical simulation of Effect of Contact Pressure on Gas Diffusion Layers deformation of a PEM Fuel Cell“. MATEC Web of Conferences 286 (2019): 09006. http://dx.doi.org/10.1051/matecconf/201928609006.
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In this study, a two-dimensional, Finite Element model has been implemented based numerical modeling simulations to predict mechanical behavior of a representative unit of fuel cell stack deformation under three levels of contact pressure between GDL and bipolar plate assuming that the GDL deformation as a combination of elastic deformation and fibers slippage. The intrusion of the GDL into the channel was estimated. Indeed, with orthotropic behavior of the GDL, the proposed nonlinear orthotropic model converges towards the models of the literature as a function of the contact pressure level between the bipolar plate and the GDL (Gas Diffusion Layers).
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Ouerghemmi, Marwa, Christophe Carral und Patrice Mele. „Experimental study of gas diffusion layers nonlinear orthotropic behavior“. E3S Web of Conferences 334 (2022): 04020. http://dx.doi.org/10.1051/e3sconf/202233404020.
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One of the most important components of PEMFC is the gas diffusion layer (GDL), owing to its key role in the reactant diffusion, water management, thermal and electron conductivity. Therefore, the GDL must have an optimal stiffness to ensure these transport functions during numerous hydrothermal cycles. The understanding of its behavior is still a remaining issue. Its orthotropic mechanical behavior requires a series of mechanical characterizations in the plane of the fibers and out of plane. In addition, there are different manufacturing processes for GDL in sheet or roll form to optimize its functional properties. A macro porous layer (MPL) or different PTFE contents might be added by different manufacturers to optimize its performance. In this study, we have performed several mechanical tests differentiating between in plane and out of plane properties in order to characterize different GDLs available on the market. All of the experimental work has been done in the machine (MD) and cross machine direction (CD) according to the fiber orientation. The different GDL types were then classified into categories presenting similar mechanical response.
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Munekata, Toshihisa, Takaji Inamuro und Shi-aki Hyodo. „Gas Transport Properties in Gas Diffusion Layers: A Lattice Boltzmann Study“. Communications in Computational Physics 9, Nr. 5 (Mai 2011): 1335–46. http://dx.doi.org/10.4208/cicp.301009.161210s.
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AbstractThe lattice Boltzmann method is applied to the investigations of the diffusivity and the permeability in the gas diffusion layer (GDL) of the polymer electrolyte fuel cell (PEFC). The effects of the configuration of water droplets, the porosity of the GDL, the viscosity ratio of water to air, and the surface wettability of the GDL are investigated. From the simulations under the PEFC operating conditions, it is found that the heterogeneous water network and the high porosity improve the diffusivity and the permeability, and the hydrophobic surface decreases the permeability.
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Zhou, Ke, Tianya Li, Yufen Han, Jihao Wang, Jia Chen und Kejian Wang. „Optimizing the hydrophobicity of GDL to improve the fuel cell performance“. RSC Advances 11, Nr. 4 (2021): 2010–19. http://dx.doi.org/10.1039/d0ra09658j.
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Massaglia, Giulia, Eve Verpoorten, Candido F. Pirri und Marzia Quaglio. „Nanostructured gas diffusion layer to improve direct oxygen reduction reaction in Air-Cathode Single-Chamber Microbial Fuel Cells“. E3S Web of Conferences 334 (2022): 04012. http://dx.doi.org/10.1051/e3sconf/202233404012.
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The aim of this work is the development of new nanostructured-gas-diffusion-layer (GDL) to improve the overall behaviour of Air-Cathode Single-Chamber-Microbial-Fuel-Cells (SCMFCs). The design of new nanostructured-GDL allowed exploiting all nanofibers ’intrinsic properties, such as high surface ratio to volume, high porosity, achieving thus a good oxygen diffusion into the proximity of catalyst layer, favouring thus the direct oxygen-reduction-reaction (ORR). Nanostructured-GDLs were prepared by electrospinning process, using a layer-by-layer deposition to collect 2 nanofibers’ mats. The first layer was made of cellulose nanofibers able to promote oxygen diffusion into SCMFC. The second layer, placed outwards, was based on polyvinyl-fluoride (PVDF) nanofibers to prevent the electrolyte leakage. This nanostructured-GDL plays a pivotal role to improve the overall performance of Air-Cathode-SCMFCs. A maximum current density of 20 mA m-2 was obtained, which is higher than the one reached with commercial-GDL, used as reference material. All results were analysed in terms of energy recovery parameter, defined as ratio of generated power integral and the internal volume of devices, evaluating the overall SCMFC performance. SCMFCs with a nanostructured-GDL showed an energy recovery equal to 60.83 mJ m-3, which was one order of magnitude higher than the one obtained with commercial-GDL, close to 3.92 mJ m-3.
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Tateyama, Shota, Takahiro Suzuki, Mitsunori Nasu, Naoki Hirayama, Masahiro Watanabe, Makoto Uchida, Akihiro Iiyama und Shohji Tsushima. „Effect of GDL Structure and Operating Conditions on PEMFC Performance and Liquid Water Removal“. ECS Transactions 114, Nr. 5 (27.09.2024): 367–75. http://dx.doi.org/10.1149/11405.0367ecst.
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Gas diffusion layers (GDLs) in proton exchange membrane fuel cells (PEMFCs) are responsible for diffusion of reactant gases into the catalyst layers, current collection and the removal of produced water. An accumulation of generated liquid water within the GDL, known as flooding, impedes the supply of reactant gas and results in the increase of concentration overpotential. Therefore, understanding of oxygen transport and produced water removal characteristics is required to enhance cell performance. The objective of this study is to investigate the effect of GDL structure and operation conditions on PEMFC performance and liquid water removal, with a particular focus on comparing a novel GDL to a conventional GDL. The results of a simultaneous evaluation of cell performance and liquid water behavior in the GDLs by means of X-ray imaging under operational conditions are presented.
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Tateyama, Shota, Takahiro Suzuki, Mitsunori Nasu, Naoki Hirayama, Masahiro Watanabe, Makoto Uchida, Akihiro Iiyama und Shohji Tsushima. „Effect of GDL Structure and Operating Conditions on PEMFC Performance and Liquid Water Removal“. ECS Transactions 114, Nr. 5 (27.09.2024): 353–61. http://dx.doi.org/10.1149/11405.0353ecst.
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Gas diffusion layers (GDLs) in proton exchange membrane fuel cells (PEMFCs) are responsible for diffusion of reactant gases into the catalyst layers, current collection and the removal of produced water. An accumulation of generated liquid water within the GDL, known as flooding, impedes the supply of reactant gas and results in the increase of concentration overpotential. Therefore, understanding of oxygen transport and produced water removal characteristics is required to enhance cell performance. The objective of this study is to investigate the effect of GDL structure and operation conditions on PEMFC performance and liquid water removal, with a particular focus on comparing a novel GDL to a conventional GDL. The results of a simultaneous evaluation of cell performance and liquid water behavior in the GDLs by means of X-ray imaging under operational conditions are presented.
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Nishida, Kosuke. „Numerical Simulation of Local Entropy Generation of Oxygen Transport in Cathode Diffusion Media of PEFC“. ECS Transactions 112, Nr. 4 (29.09.2023): 43–48. http://dx.doi.org/10.1149/11204.0043ecst.
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The oxygen transport in cathode electrodes of polymer electrolyte fuel cells (PEFCs) is a key process for determining their power generation performance. To identify the factors affecting its transport loss, this study introduced the analysis of local entropy generation into the conventional two-phase flow simulation in the cathode gas diffusion layer (GDL) of a PEFC and estimated the distribution of the entropy production rate due to oxygen diffusion. The effect of land-channel geometry on its entropy generation in the GDL was also evaluated. The results revealed that the entropy generation of oxygen diffusion becomes remarkably high under the boundary between the channel and land that causes its large concentration gradient. It was also found that the entropy generation due to oxygen diffusion in the GDL increases with an increase in the water accumulation during the operation.
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Edjokola, Joel Mata, Viktor Hacker und Merit Bodner. „Investigation of Gas Diffusion Layer Degradation in Polymer Electrolyte Fuel Cell Via Chemical Oxidation“. ECS Transactions 112, Nr. 4 (29.09.2023): 265–71. http://dx.doi.org/10.1149/11204.0265ecst.
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The gas diffusion layer (GDL) enables and influences the internal transport of fuel, oxygen, electricity, heat and water. The GDL is made up of the macroporous substrate and the microporous layer. To achieve the hydrophobicity required for water management, the two layers are typically treated with polytetrafluoroethylene (PTFE). Degradation of GDL, including carbon corrosion and PTFE loss, affects water management, conductivity and mass transport. GDLs were subjected to accelerated stress tests by immersing them in Fenton's reagent for 24 hours. Analysis of hydrophobic properties through contact angle measurements, thermogravimetry, and energy dispersive X-ray spectroscopy indicated that the hydrophobicity of the GDL exposed to Fenton's reagent decreased. This loss of hydrophobicity is associated with surface oxidation and PTFE degradation.
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Raciti, David, Trevor Michael Braun, Brian Tackett, Heng Xu, Mutya Cruz, Benjamin Wiley und Thomas P. Moffat. „Self-Supporting Ag Nanowire Mat Electrodes on PTFE Gas Diffusion Layers for Electrochemical Conversion of CO2 to CO“. ECS Meeting Abstracts MA2022-02, Nr. 40 (09.10.2022): 1489. http://dx.doi.org/10.1149/ma2022-02401489mtgabs.
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High surface area nanocatalysts combined with conductive carbon-based gas-diffusion layers (GDL) enable high CO2 flux and conversion, but can suffer from ineffective catalyst utilization and flooding of the GDL ultimately limiting the lifetime of electrolyzer operation. Herein we explore an alternative gas-diffusion electrode that incorporates a self-conducting network of Ag nanowires on a non-conductive PTFE GDL (Figure 1 a-b) as a gas-diffusion electrode (GDE) for CO2 conversion (Figure 1 c-d). Properties influenced by Ag nanowire mat thickness and durability of the Ag nanowires are explored. Furthermore a 1-D model of the electrode morphology and microstructure quantitatively captures the steady-state compositional gradients (Figure 1d) within the catalyst layer giving insight into the observed empirical differences in catalyst layer thickness. The self-conductive nanowire network and robust hydrophobic porous support structure provide an effective platform to further understanding of meso-scale properties and microenvironment present during CO2 electroreduction. Figure Caption: (a) Top-down and (b) Cross-section electron micrographs of a Ag nanowire covered PTFE GDL. (c) Schematic depicting the utilization of the Ag NW covered PTFE GDL as an electrode for electrochemical CO2 reduction and (d) resulting relationships between catalyst layer thickness, mass activity and simulated local pH. Figure 1
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Saka, Kenan, Mehmet Fatih Orhan und Ahmed T. Hamada. „Design and Analysis of Gas Diffusion Layers in a Proton Exchange Membrane Fuel Cell“. Coatings 13, Nr. 1 (20.12.2022): 2. http://dx.doi.org/10.3390/coatings13010002.
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A proton exchange membrane fuel cell is an energy convertor that produces environmentally friendly electrical energy by oxidation of hydrogen, with water and heat being byproducts. This study investigates the gas diffusion layer (GDL) of the membrane electrode assembly (MEA) in proton exchange membrane fuel cells (PEMFCs). In this regard, the key design concerns and restraints of the GDL have been assessed, accompanied by an inclusive evaluation of the presently existing models. In addition, the common materials used for the GDL have been explored, evaluating their properties. Moreover, a case study of step-by-step modeling for an optimal GDL has been presented. An experimental test has been carried out on a single cell under various compressions. Lastly, a parametric study has been performed considering many design parameters, such as porosity, permeability, geometrical sizes, and compression of the GDL to improve the overall efficiency of the fuel cell. The results are presented in this paper in order to help ongoing efforts to improve the efficiency of PEMFCs and facilitate their development further.
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Indayaningsih, Nanik, Dedi Priadi, Anne Zulfia und Suprapedi. „Analysis of Coconut Carbon Fibers for Gas Diffusion Layer Material“. Key Engineering Materials 462-463 (Januar 2011): 937–42. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.937.
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The main compound of natural fibers is a hydrocarbon. The heating of hydrocarbon in inert gas produces charcoal or carbon. Carbon materials are widely used for several purposes depending on the physical and electric properties, for example for hydrogen storage, conductive or reinforced plastics, catalyst supports, batteries and fuel cells. The main raw material of Gas diffusion Layer (GDL) of the Proton Exchange Membrane Fuel Cell (PEMFC) is a carbon. The properties of GDL are porous and electron-conductive material, because of the function of GDL is to distribute the gas as fuel and electricity conductors. This study aims to analyze the carbon fibers made from coconut fibers for the application of GDL materials. The carbon fiber was made using pyrolysis process in the inert gas (nitrogen) at a certain temperature according to the analysis of Differential Thermal Analysis (DTA) 3000C, 4000C, 5000C, 6000C, and 9000C. The crystalstructure, carbon content, powder density and morphology of carbon fibers were observed using X-Ray Diffraction (XRD), fixed carbon according to ASTM D 1762-64, Archimedes method (BS 19202 Part 1A), and Scanning Electron Microscope (SEM), respectively. The results showed that the structure of carbon was amorphous, and content of 51% ̶ 71%, powder density of 0.42g/cm3 ̶ 0.71g/cm3. The morphology having many parallel hollows like a tube that are close to each other with diameters of 2m ̶ 10m, and in the wall of tube there are some porous with sizes around 1m. According to this analysis, the coconut carbon fiber enables to be applied as candidate for a basic material of GDL.
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Hussain, Javid, Dae-Kyeom Kim, Sangmin Park, Muhammad Waqas Khalid, Sayed-Sajid Hussain, Ammad Ali, Bin Lee, Myungsuk Song und Taek-Soo Kim. „Experimental and Computational Study of Optimized Gas Diffusion Layer for Polymer Electrolyte Membrane Electrolyzer“. Materials 16, Nr. 13 (23.06.2023): 4554. http://dx.doi.org/10.3390/ma16134554.
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Polymer electrolyte membrane fuel cells (PEMFCs) and PEM electrolyzer are emerging technologies that produce energy with zero carbon emissions. However, the commercial feasibility of these technologies mostly relies on their efficiency, which is determined by individual parts, including the gas diffusion layer (GDL). GDL transfers fluid and charges while protecting other components form flooding and corrosion. As there is a very limited attention toward the simulation work, in this work, a novel approach was utilized that combines simulation and experimental techniques to optimize the sintering temperature of GDL. Ti64 GDL was produced through tape casting, a commercial method famous for producing precise thickness, uniform, and high-quality films and parameters such as slurry composition and rheology, casting parameters, drying, and debinding were optimized. The porosity and mechanical properties of the samples were tested experimentally at various sintering temperatures. The experimental results were compared with the simulated results achieved from the GeoDict simulation tool, showing around 96% accuracy, indicating that employing GeoDict to optimize the properties of Ti64 GDL produced via tape casting is a critical step towards the commercial feasibility of PEMFCs and electrolyzer. These findings significantly contribute to the development of sustainable energy solutions.
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Lee, Haksung, Chan-Woong Choi, Ki-Weon Kang und Ji-Won Jin. „A Study on the Evaluation of Effective Properties of Randomly Distributed Gas Diffusion Layer (GDL) Tissues with Different Compression Ratios“. Applied Sciences 10, Nr. 21 (22.10.2020): 7407. http://dx.doi.org/10.3390/app10217407.
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The gas diffusion layer (GDL) typically consists of a thin layer of carbon fiber paper, carbon cloth or nonwoven and has numerous pores. The GDL plays an important role that determines the performance of the fuel cell. It is a medium through which hydrogen and oxygen are transferred and serves as a passage through which water, generated by the electrochemical reaction, is discharged. The GDL tissue undergoes a compressive loading during the stacking process. This leads to changes in fiber content, porosity and resin content due to compressive load, which affects the mechanical, chemical and electrical properties of the GDL and ultimately determines fuel cell performance. In this study, the geometry of a GDL was modeled according to the compression ratios (10%, 20%, 30%, 40% and 50%), which simulated the compression during the stacking process and predicted the equivalent properties according to the change of GDL carbon fiber content, matrix content and pore porosity, etc. The proposed method to predict the equivalent material properties can not only consider the stacking direction of the material during stack assembling process, but can also provide a manufacturing standard for fastening compressive load for GDL.
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Zhu, Yingli, Xiaojian Zhang, Jianyu Li und Gary Qi. „Three-dimensional graphene as gas diffusion layer for micro direct methanol fuel cell“. International Journal of Modern Physics B 32, Nr. 12 (03.05.2018): 1850145. http://dx.doi.org/10.1142/s021797921850145x.
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The gas diffusion layer (GDL), as an important structure of the membrane electrode assembly (MEA) of the direct methanol fuel cell (DMFC), provides a support layer for the catalyst and the fuel and the product channel. Traditionally, the material of GDL is generally carbon paper (CP). In this paper, a new material, namely three-dimensional graphene (3DG) is used as GDL for micro DMFC. The experimental results reveal that the performance of the DMFC has been improved significantly by application of 3DG. The peak powers increase from 25 mW to 31.2 mW and 32 mW by using 3DG as the anode and cathode GDL instead of CP, respectively. The reason may be the decrease of charge and mass transfer resistance of the cell. This means that the unique 3D porous architecture of the 3DG can provide lower contact resistance and sufficient fuel diffusion paths. The output performance of the cell will be further improved when porous metal current collectors is used.
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Berger, Anne, und Hubert Andreas Gasteiger. „Determination of the τ/ε-Ratio for Gas Diffusion Substrates and Microporous Layers in an Operating Fuel Cell“. ECS Meeting Abstracts MA2022-01, Nr. 35 (07.07.2022): 1456. http://dx.doi.org/10.1149/ma2022-01351456mtgabs.
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Proton-exchange-membrane fuel cells (PEMFCs) are expected to play a major role in the electrification of the transportation sector,[1] with recent focus shifting to the heavy-duty market. One essential aspect for increasing the power density of a PEMFC is optimizing the mass transport in the gas diffusion layer (GDL) on the cathode side of the cell. A careful choice of the commonly used carbon fiber based GDL is therefore necessary to optimize the performance at different relative humidity conditions. Among other important GDL properties such as the pore size distribution and the thermal conductivity, the porosity (ε) and the tortuosity (τ) are important descriptors. The τ/ε-ratio has been characterized for diffusion media using in-situ or ex-situ techniques.[2-3] This study is based on the theory developed by Baker et al.[2] In addition to their work, which solely considers molecular diffusion, we will present a method to include Knudsen diffusion occurring in smaller pores for the in-situ evaluation of the τ/ε-ratio. This adaptation makes it possible to evaluate GDL substrates to which carbon black (creating small pores) has been added to increase the electrical conductivity,[4] and also to extend the theory to the microporous layer (MPL). In this study, we characterize the τ/ε-ratio for two GDL substrates (without the addition of an MPL), one from Toray and one from Freudenberg, using limiting current measurements in an operating fuel cell. The τ/ε-ratio describes the deviation of the effective diffusivity compared to ideal molecular diffusion. However, depending of the range of pore diameters in the gas diffusion medium, a mixture of molecular diffusion and Knudsen diffusion has to be taken into account. Fig. 1 shows the theoretical contribution ratio of Knudsen diffusion and molecular diffusion (left y-axis) versus the relevant range of pore diameters for different pressures. The graphic illustrates that Knudsen diffusion dominates at lower pore sizes, while molecular diffusion is mostly present at larger pore sizes. An increase in pressure shifts the regime of molecular diffusion to smaller pores. In addition to the theoretical contribution ratio, Fig. 1 depicts the pore size distribution of a Toray and a Freudenberg GDL substrate determined by mercury intrusion porosimetry (MIP). While the Toray paper has a narrow pore size distribution at pores of 30-50 µm, where only molecular diffusion occurs, the Freudenberg GDL contains a broader range of larger pores at 10-40 µm (molecular diffusion) together with the presence of small pores at ca. 70-80 nm that derive from the addition of carbon black and that present a medium where Knudsen and molecular diffusion occur. After the validation of the principle, the method is transferred to determine the τ/ε-number of a microporous layer based on vapor-grown carbon-fibers (VGCF), whose transport properties in a PEMFC have been described previously.[5] References [1] O. Gröger, H. A. Gasteiger, J.-P. Suchsland, J. Electrochem. Soc. 2015, 162, A2605-A2622. [2] D. R. Baker, D. A. Caulk, K. C. Neyerlin, M. W. Murphy, J. Electrochem. Soc. 2009, 156, B991. [3] D. Kramer, S. A. Freunberger, R. Flückiger, I. A. Schneider, A. Wokaun, F. N. Büchi, G. G. Scherer, Journal of Electroanalytical Chemistry 2008, 612, 63-77. [4] K.-D. Wagner, A. Bock, K. Salama, A. Weller, Vol. US 2010/0219069 A1, Carl Freudenberg KG 2010. [5] C. Simon, J. Endres, B. Nefzger-Loders, F. Wilhelm, H. A. Gasteiger, J. Electrochem. Soc. 2019, 166, F1022-F1035. Acknowledgements We gratefully acknowledge funding from the Swiss National Foundation under the funding scheme Sinergia (project grant number 180335). We also thank Michael Striednig and Christoph Simon for initial work on the topic. Figure 1: Left y-axis: theoretical contribution ratio of Knudsen (green) and molecular diffusion (orange) versus pore diameter for different absolute pressures of 115 kPaabs (solid lines), 150 kPaabs (dashed lines), 200 kPaabs (dotted lines), and 300 kPaabs (dash-dotted lines). With smaller pores and lower pressures, more contributions from Knudsen diffusion can be expected. Right y-axis: log. differential intrusion measured by MIP analysis for the Toray (blue) and the Freudenberg (grey) GDL substrates, whereby the Freudenberg GDL shows pores at ~70-80 nm that are caused by the addition of carbon black. Figure 1
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Yasin, Nor Hafizah Yasin, und Wan Zaireen Nisa Yahya. „IMMOBILISATION OF COPPER (I) OXIDE/ZINC OXIDE NANOPARTICLES ON THE GAS DIFFUSION LAYER FOR CO2 REDUCTION REACTION APPLICATION“. Malaysian Journal of Science 43, sp1 (31.07.2024): 8–14. http://dx.doi.org/10.22452/mjs.vol43sp1.2.
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The electrochemical reduction of carbon dioxide (CO₂RR) represents a promising strategy for CO₂ mitigation, requiring highly efficient catalysts integrated into electrochemical devices to achieve high conversion rates and energy efficiencies for desired products. Establishing a gas diffusion electrode is crucial for practical applications of CO₂ electrochemical reduction reactions (CO₂RR). This study uses the air-spraying method to immobilise nano-catalysts onto a gas diffusion layer (GDL) with exceptional homogeneity. A composite of copper(I) oxide (Cu₂O) and zinc oxide (ZnO) nanoparticles in a 4:1 ratio was deposited onto the GDL. Surface morphology analysis revealed the successful immobilisation of cubic Cu₂O and hexagonal wurtzite ZnO with a uniform distribution, indicating potential improvements in CO₂RR performance. Contact angle measurements were conducted to assess surface hydrophobicity, comparing pristine GDL with Cu₂O/ZnO-based GDL. Although the contact angle on the surface of the Cu₂O/ZnO-based GDL slightly reduced from 143.69° to 134.82°, it maintained its hydrophobic nature. This reduction is attributed to Nafion, a binder in the catalyst ink mixture. The sustained high contact angle is crucial for the CO₂ reduction reaction process. X-ray diffraction (XRD) diffractograms of Cu₂O/ZnO-based GDL were compared with reference Cu₂O, ZnO, and bare GDL. The presence of all essential peaks confirms the successful immobilisation. The air-spraying technique effectively achieved a favourable distribution of active metals.
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Yang, Danan, Himani Garg, Steven B. Beale und Martin Andersson. „Numerical Reconstruction of Proton Exchange Membrane Fuel Cell Gas Diffusion Layers“. ECS Meeting Abstracts MA2023-02, Nr. 37 (22.12.2023): 1718. http://dx.doi.org/10.1149/ma2023-02371718mtgabs.
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Flooding and dehydration reduce stability and power performance in Proton Exchange Membrane Fuel Cells (PEMFCs). The Gas Diffusion Layer (GDL) plays a crucial role in facilitating reactant gas transport and removing product water from the electrode. To suit various PEMFCs, GDLs with different shapes have been commercialized. The impact of the GDL structure on the surface-tension-driven water transport behavior remains poorly understood. However, this is one important aspect that can be controlled by proper design. In this study, the GDL performance is investigated by comparing curved and straight carbon fibers within the region. Specifically, an image-processing method extracts porosity, domain size, and fiber diameter from an experimental image-based GDL reconstruction. These parameters are utilized by in-house developed computer codes to stochastically reconstruct curved and straight carbon fiber GDLs, respectively. The real and reconstructed GDLs are compared in terms of pore size distribution, tortuosity, and permeability. Liquid transport in these GDLs and corresponding gas channels is simulated using a volume of fluid method in OpenFOAM 7.0. Figure 1(a) presents the T-shaped simulation domain and top view of three GDLs. Figure 1(b) displays the Cumulative Density Function (CDF) of the pore size distribution for the three GDLs, revealing that the main difference between the three GDLs lies in the pore diameter range of 10-30 µm. Upon completion of the research program, we aim to identify the influence of fiber shape on the GDL transport properties as well as the water behavior inside them. Figure 1
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Peng, Ming, Enci Dong, Li Chen, Yu Wang und Wen-Quan Tao. „Effects of Cathode Gas Diffusion Layer Configuration on the Performance of Open Cathode Air-Cooled Polymer Electrolyte Membrane Fuel Cell“. Energies 15, Nr. 17 (28.08.2022): 6262. http://dx.doi.org/10.3390/en15176262.
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The design of a gas diffusion layer (GDL) is an effective way to manage water transport, thus improving the performance of air-cooled fuel cells. In the present study, three group designs of GDL with polytetrafluoroethylene (PTFE)—uniformly doped, in-planed sandwich doped and through-plane gradient doped—are proposed, and their effects on the performance of air-cooled fuel cells are explored by numerical simulation. The distribution of key physical quantities in the cathode catalyst layer (CCL), current density and the uniformity of current density distribution in the CCL were analyzed in detail. The results show that properly reducing the amount of PTFE in GDL is beneficial to promoting the water retaining capacity of air-cooled fuel cells, and then improving the performance of fuel cells. The performance of the in-plane sandwich GDL design cannot exceed the design with 10% PTFE uniformly doped, and this design will aggravate the uneven distribution of current density in CCL. Compared with the design of GDL with 40% PTFE uniformly doped, the current density can be improved by 22% when operating at 0.6 V by gradient increasing the PTFE content in GDL from the GDL/MPL interface to the gas channel. Furthermore, this design can maintain as good a current density uniformity as uniformly doping schemes.
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Berger, Anne, Yen-Chun Chen, Jacqueline Gatzemeier, Thomas J. Schmidt, Felix N. Büchi und Hubert A. Gasteiger. „Analysis of the MPL/GDL Interface: Impact of MPL Intrusion into the GDL Substrate“. Journal of The Electrochemical Society 170, Nr. 9 (01.09.2023): 094509. http://dx.doi.org/10.1149/1945-7111/acfa26.
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Interfaces are crucial for the water management in polymer electrolyte membrane fuel cells (PEMFCs). The introduction of a microporous layer (MPL) had a revolutionary effect on the water distribution by improving the interface between the catalyst layer and the gas diffusion layer substrate (GDL-S). Hence, it is vital to maximize the improvement by further characterizing and advancing the properties of the interfaces, in this case the MPL/GDL-S interface. This study aims at fabricating a GDL with an MPL that intrudes into the GDL-S, analyzing the impact on the GDL-S structure and on PEMFC performance. Mercury intrusion porosimetry (MIP) and ex situ X-ray tomography (XTM) show that the intrusion of the MPL into the hydrophobic GDL-S proceeds via the preferential filling of the GDL-S macropores, thereby reducing their size and volume fraction in the GDL-S. While an intruding MPL leads to a small performance increase under wet PEMFC operating conditions, this improvement could only be achieved by a careful management between the extent of MPL intrusion and the partial macropore blocking in the GDL-S. Furthermore, the impact of MPL intrusion on the liquid water saturation of the GDL was quantified by operando XTM. The results provide design guidelines for improved GDLs.
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Pourrahmani, Hossein, Hamza Moussaoui, Milad Hosseini, Majid Siavashi, Lucie Navratilova, Mardit Matian und Jan Van herle. „Fluid Flow in the Gas Diffusion Layer Using Computational Fluid Dynamics and Microscopy Techniques“. ECS Meeting Abstracts MA2023-01, Nr. 24 (28.08.2023): 1595. http://dx.doi.org/10.1149/ma2023-01241595mtgabs.
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The utilization of a proton exchange membrane fuel cell (PEMFC) as an energy provider using hydrogen as a fuel has increased drastically. The reasons are the current limitation of fossil fuel-based devices, pollutants-free, high efficiency, and zero-carbon emission. The life-cycle assessment results of this type of fuel cell have also indicated the lowest contribution to global warming, human health, and resource scarcity in comparison to other types of fuel cells. In this regard, improving the performance of PEMFC is of importance. As an important component of the PEMFC, the gas diffusion layer (GDL) transports the gas reactants to the catalyst layer with the least electrical resistance. The GDL is often made of carbon fibers and should have a surface with good electrical contact and hydrophobic properties to facilitate the water removal. Remaining water in the GDL will result in difficulties during the cold-start and enhances the degradation of this layer. It is believed that the water removal of the GDL has a direct relationship with the capillary pressure, which is strongly linked to the GDL’s microstructure and wettability. However, further investigations can be done once a comprehensive simulation model is developed to monitor the changes in the GDL liquid removal by the effective parameters. In this regard, the Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) has been used to perform three-dimensional cross-section imaging of the GDL. The GDL samples are provided by Freudenberg in which the Microporous layer (MPL) is impregnated into the GDL. The average porosity of this sample is in the range of 75% while having the in-plane gas permeability of 2.4 under a compressive stress of 1 MPa. The utilized resin for FIB-SEM imaging is a mixture of Epoxy embedding medium (diglycidyl ether of bisphenol – A) with two different hardeners DDSA (2-Dodecenylsuccinic anhydride) and MNA (Methylnadic anhydride), which will be mixed with DPM – 30 [2,4,6 – Tris(dimethylaminomethyl)phenol] as the accelerator, all provided by Sigma Aldrich. After the preparation of the resin, 0.4 gr of Cobalt (II) acetylacetonate nanoparticles (supported by Sigma Aldrich) were added to 7.14 ml of the resin to improve the contrast of the images. The samples were impregnated with the resin under vacuum to be pressurized (3 MPa) for 20 minutes, and afterward, heated in an oven at 60℃ for 12 hours. The surfaces for analyses were cut by a diamond wire, polished by abrasive plates down to 0.1 and gold coated (20nm). FIB-SEM acquisition consisted of the polishing of cross-sections with a focused ion beam (LMIS Ga+ source) at 30 keV and 1 nA (Zeiss Crossbeam 540), followed by imaging with an electron beam at acceleration voltages of 1.0, 3.0 kV. Milling and imaging were performed at a working distance of 5.2 mm and stage tilt of 54°, i.e., the coincidence point of the electron and ion beams. Once the three-dimensional cross-sections of the GDL are obtained, the segmentation and reconstruction will be made to provide the needed geometry for fluid flow simulation and to calculate the microstructural properties. Fig. 1 shows the generated structure of the GDL after the segmentation and reconstruction of the cross-section images. The geometry will be then used to characterize the effective parameters of the thermal/water management of the PEMFC. This study can also be a valid reference for future computational fluid dynamic analyses in the GDL using the numerical modeling with the conservative equations or the Lattice Boltzmann modeling (LBM) with the kinetic and particle distribution equations. Keywords : Proton exchange membrane fuel cell (PEMFC); Gas Diffusion Layer (GDL); Focused Ion Beam- Scanning Electron Microscopy (FIB-SEM); Three-dimensional simulation; Lattice Boltzmann method (LBM) Figure 1
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Wang, Hao, Guogang Yang, Shian Li, Qiuwan Shen, Yue Li und Renjie Wang. „Pore-Scale Modeling of Liquid Water Transport in Compressed Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells Considering Fiber Anisotropy“. Membranes 13, Nr. 6 (29.05.2023): 559. http://dx.doi.org/10.3390/membranes13060559.
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Water management of the gas diffusion layer (GDL) is crucial to the performance of proton exchange membrane fuel cells (PEMFCs). Appropriate water management ensures efficient transport of reactive gases and maintains wetting of the proton exchange membrane to enhance proton conduction. In this paper, a two-dimensional pseudo-potential multiphase lattice Boltzmann model is developed to study liquid water transport within the GDL. Liquid water transport from the GDL to the gas channel is the focus, and the effect of fiber anisotropy and compression on water management is evaluated. The results show that the fiber distribution approximately perpendicular to the rib reduces liquid water saturation within the GDL. Compression significantly changes the microstructure of the GDL under the ribs, which facilitates the formation of liquid water transport pathways under the gas channel, and the increase in the compression ratio leads to a decrease in liquid water saturation. The performed microstructure analysis and the pore-scale two-phase behavior simulation study comprise a promising technique for optimizing liquid water transport within the GDL.
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Guo, Hui, Lubing Chen, Sara Adeeba Ismail, Lulu Jiang, Shihang Guo, Jie Gu, Xiaorong Zhang et al. „Gas Diffusion Layer for Proton Exchange Membrane Fuel Cells: A Review“. Materials 15, Nr. 24 (09.12.2022): 8800. http://dx.doi.org/10.3390/ma15248800.
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Proton exchange membrane fuel cells (PEMFCs) are an attractive type of fuel cell that have received successful commercialization, benefitted from its unique advantages (including an all solid-state structure, a low operating temperature and low environmental impact). In general, the structure of PEMFCs can be regarded as a sequential stacking of functional layers, among which the gas diffusion layer (GDL) plays an important role in connecting bipolar plates and catalyst layers both physically and electrically, offering a route for gas diffusion and drainage and providing mechanical support to the membrane electrode assemblies. The GDL commonly contains two layers; one is a thick and rigid macroporous substrate (MPS) and the other is a thin microporous layer (MPL), both with special functions. This work provides a brief review on the GDL to explain its structure and functions, summarize recent progress and outline future perspectives.
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Yan, Song, Mingyang Yang, Chuanyu Sun und Sichuan Xu. „Liquid Water Characteristics in the Compressed Gradient Porosity Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells Using the Lattice Boltzmann Method“. Energies 16, Nr. 16 (16.08.2023): 6010. http://dx.doi.org/10.3390/en16166010.
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The mitigation of water flooding in the gas diffusion layer (GDL) at relatively high current densities is indispensable for enhancing the performance of proton exchange membrane fuel cells (PEMFCs). In this paper, a 2D multicomponent LBM model is developed to investigate the effects of porosity distribution and compression on the liquid water dynamic behaviors and distribution. The results suggest that adopting the gradient GDL structure with increasing porosity along the thickness direction significantly reduces the breakthrough time and steady–state total water saturation inside the GDL. Moreover, the positive gradient structure reaches the highest breakthrough time and water saturation at 10% compression ratio (CR) when the GDL is compressed, and the corresponding values decrease with further increase of the CR. Considering the breakthrough time, total water saturation and water distribution at the entrance of the GDL at the same time, the gradient structure with continuously increasing porosity can perform better water management capacity at 30% CR. This paper is useful for understanding the two–phase process in a gradient GDL structure and provides guidance for future design and manufacturing.
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ZHENG, QIAN, JINTU FAN, XIANGPENG LI und CHAO XU. „FRACTAL ANALYSIS OF GAS FLOW THROUGH THE GAS DIFFUSION LAYER IN PROTON EXCHANGE MEMBRANE FUEL CELLS WITH ROUGHENED MICRO-CHANNELS“. Fractals 26, Nr. 06 (Dezember 2018): 1850099. http://dx.doi.org/10.1142/s0218348x18500998.
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The effective permeability is one of the key parameters for porous fibrous gas diffusion layer (GDL), which plays a crucial role in the proton exchange membrane fuel cells (PEMFCs). However, the effect of the surface morphology of porous fibrous GDL on gas transport behaviors is so far been neglected. In order to take that into consideration, a new analytical model is presented for gas flow in porous fibrous GDL with roughened micro-channels based on the fractal scaling laws. Due to the existence of very small pores in the porous fibrous GDL, gas slippage effects through the small pores are also taken into account. The fractal gas permeability is expressed in terms of the relative roughness, other microstructural parameters as well as gas properties. The proposed fractal model is validated by comparing the model prediction with available experimental data. The effect of relative roughness and other micro-structural parameters of GDL on the permeability is analyzed in detail.
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Moriyama, Koji, und Takaji Inamuro. „Lattice Boltzmann Simulations of Water Transport from the Gas Diffusion Layer to the Gas Channel in PEFC“. Communications in Computational Physics 9, Nr. 5 (Mai 2011): 1206–18. http://dx.doi.org/10.4208/cicp.311009.081110s.
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AbstractWater management is a key to ensuring high performance and durability of polymer electrolyte fuel cell (PEFC), and it is important to understand the behavior of liquid water in PEFC. In this study, the two-phase lattice Boltzmann method is applied to the simulations of water discharge from gas diffusion layers (GDL) to gas channels. The GDL is porous media composed of carbon fibers with hydrophobic treatment, and the gas channels are hydrophilic micro-scale ducts. In the simulations, arbitrarily generated porous materials are used as the structures of the GDL. We investigate the effects of solid surface wettabilities on water distribution in the gas channels and the GDL. Moreover, the results of X-ray computed tomography images in the operating PEFC are compared with the numerical simulations, and the mechanism of the water transport in PEFC is considered.
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Kulikovsky, Andrei. „Analytical Impedance of Oxygen Transport in the Channel and Gas Diffusion Layer of a PEM Fuel Cell“. Journal of The Electrochemical Society 168, Nr. 11 (01.11.2021): 114520. http://dx.doi.org/10.1149/1945-7111/ac3a2d.
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Analytical model for impedance of oxygen transport in the gas–diffusion layer (GDL) and cathode channel of a PEM fuel cell is developed. The model is based on transient oxygen mass conservation equations coupled to the proton current conservation equation in the catalyst layer. Analytical formula for the “GDL+channel” impedance is derived assuming fast oxygen and proton transport in the cathode catalyst layer (CCL) In the Nyquist plot, the transport impedance consists of two arcs describing oxygen transport in the air channel (low–frequency arc) and in the GDL. The characteristic frequency of GDL arc depends on the CCL thickness: large CCL thickness strongly lowers this frequency. At small CCL thickness, the high–frequency feature on the arc shape forms. This effect is important for identification of peaks in distribution of relaxation times spectra of low–Pt PEMFCs.
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Seo, Sangwon, Kwangyeop Jang, Jongwoo Park und Dongjin Kim. „Synthesis of PTFE based Air Cathode for Metal Air Battery“. E3S Web of Conferences 233 (2021): 01005. http://dx.doi.org/10.1051/e3sconf/202123301005.
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A large number of researchers devotes deep study to reducing the contact resistance and improving the durability of air cathode. Air cathode consists of gas diffusion layer, current collector and catalytic layers. The network structure (gas diffusion layer, GDL) of Air cathode plays an important role in metal-air battery. This GDL makes the air-cathode semi-permiable. It means that H2O does not pass through GDL layer but O2 moleecules can pass the layer. For that reason, the optimization of sintering condition is very important process in manufacturing Air cathode. This article is about the dependence of discharge property of magnesium air-battery to its sinter-ability. Thus in order to observe any changes in the discharge property, sinter-ability, a cost-effective method was designed in the air cathode production.
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Lee, So Yeon, Chi-Yeong Ahn und Hyungwon Shim. „An Experimental Study on the Correlation between Characteristics of Gas Diffusion Layer and Performance Depending on Relative Humidity Variation in Proton Exchange Membrane Fuel Cell“. ECS Meeting Abstracts MA2023-02, Nr. 38 (22.12.2023): 1874. http://dx.doi.org/10.1149/ma2023-02381874mtgabs.
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As it is well known, Gas diffusion Layer(GDL) is a fundamental element to provide more efficient water transport in Proton Exchange Membrane Fuel Cell(PEMFC). Numerous previous studies showed how important and critical GDL is in PEMFC. There have been many efforts to improve the performance of GDL, such as studies on properties, structural improvement, and hydrophobic coating on substrate and micro porous layer. Through these efforts, PEMFC has been developed and also the relationship between GDL and each component was investigated well. Relative Humidity(RH) is an important factor that affects proton conductivity and mass transport and is also an factor to be considered for water management. Although it should be relatively clear, it is necessary to compare and verify between the numerical study and experimental study since they does not always matches. In this study, the results were compared with the physical properties of each GDL based on experimental data applying GDL with different characteristics. We studied to reveal the correlation between data such as thickness, porosity, and pore distribution of GDL and I-V Polarization curve conducted by changing RH conditions to investigate performance.
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Halter, Jonathan, John A. MacDonald, Fabusuyi Akindele Aroge, Olivia C. Lowe, Francesco P. Orfino, Esmaeil Navaei Alvar, Monica Dutta und Erik Kjeang. „The Role of Thermal Conductivity on Liquid Water Distribution in GDLs“. ECS Meeting Abstracts MA2023-02, Nr. 37 (22.12.2023): 1786. http://dx.doi.org/10.1149/ma2023-02371786mtgabs.
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Operating polymer electrolyte fuel cells (PEFCs) at increasingly higher current density and efficiency necessitates overall improvements in fuel cell water management [1]. A crucial role facilitating these improvements is played by the gas diffusion layer (GDL) within the membrane electrode assembly (MEA) [2]. The GDL is responsible for distributing the reactant gases from the flow field towards the catalyst layer as well as removing reaction products from the catalyst layer to the flow fields. For example, at the cathode, the electrochemical reaction of oxygen ions with protons and excess electrons yields water and heat, which must be removed through the GDL to the flow field. The removal of water through the GDL can lead to blocked pores in the GDL [2], thereby restricting the reactants’ gas flow towards the catalyst layer causing mass transport losses. GDL design is crucial towards improving the performance of PEFCs, especially at high current densities, such that it minimizes these transport losses. Additionally, removal of the excess heat generated at the cathode catalyst layer through the GDL indicates that the GDL thermal conductivity (k) plays a crucial role affecting the temperature distribution within the MEA [3]. In this work, two GDLs varying in thermal conductivity were selected and assembled in MEAs which were then imaged in-operando using X-ray tomographic microscopy [4]. In-Operando imaging allowed the evaluation of the liquid water distribution at steady state over a range of operational conditions such as temperature and current density. Water distribution results for a range of current densities will be presented for selected cell temperatures between 40 and 70 °C. For GDL I with the lower thermal conductivity, the channels are completely dry at 40 °C. For GDL II with the higher thermal conductivity, a wet-dry transition was observed in between 50 and 70°C. High saturations were observed in both the channel and the land regions at 50 °C, while at 70 °C the channels appear to be dry with liquid water only being present under the lands (see Figure 1). These results provide experimental evidence of a major influence of GDL thermal conductivity on liquid water distribution and overall water management in fuel cells. Keywords – operando, X-ray tomographic microscopy, GDL, water visualization Acknowledgement Funding for this research was provided by the Natural Sciences and Engineering Research Council of Canada, Ballard Power Systems, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, and Canada Research Chairs. References [1] Y. Nagai, J. Eller, T. Hatanaka, S. Yamaguchi, S. Kato, A. Kato, F. Marone, H. Xu and F. N. Buechi, "Improving water management in fuel cells through microporous layer modifications: Fast operando tomographic imaging of liquid water," Journal of Power Sources, vol. 435, 2019. [2] H. Xu, M. Buehrer, F. Marone, T. J. Schmidt, F. N. Buechi and J. Eller, "Effects of Gas Diffusion Layer Substrates on PEFC Water Management: Part I Operando Liquid Water Saturation and Gas Diffusion Properties," Journal of The Electrochemical Society, vol. 168, 2021. [3] D.A. Chaulk and D. R. Baker, "Heat and Water Transport in Hydrophobic Diffusion Media of PEM Fuel Cells," Journal of The Electrochemical Society, vol. 157, 2010. [4] F. A. Aroge, B. S. Parimalam, J. A. MacDonald, F. P. Orfino, M. Dutta and E. Kjeang, "Analysing operando 2D X-ray transmission images for liquid water distribution in polymer electrolyte fuel cells," Journal of Power Sources, vol. 564, 2023. Figure 1
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Sun, Chao, Qing Du, Yan Yin und Bin Jia. „Numerical Simulation of Water Removal Process in the Microstructure of Gas Diffusion Layer with Mechanics Properties and Material Properties“. Advanced Materials Research 625 (Dezember 2012): 41–44. http://dx.doi.org/10.4028/www.scientific.net/amr.625.41.
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The performance of proton exchange membrane fuel cell is greatly influenced by the presence, distribution and transport of liquid water in the gas diffusion layer (GDL). In this study, air-water flow in a 3D GDL microstructure along the in-plane direction is studied numerically by using the volume of fluid (VOF) method. The GDL microstructure is considered initially filled with water, air flows into the structure under the driving force of a set pressure drop and the flow is supported by the capillary pressure due to the hydrophobic nature of the GDL structure. It is found that water removal can be accelerated by improving pressure drop. Pressure drop has little influence on the state-steady water volume fraction when the pressure drop is over a critical value.
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Anyanwu, Ikechukwu S., Zhiqiang Niu, Daokuan Jiao, Aezid-Ul-Hassan Najmi, Zhi Liu und Kui Jiao. „Liquid Water Transport Behavior at GDL-Channel Interface of a Wave-Like Channel“. Energies 13, Nr. 11 (28.05.2020): 2726. http://dx.doi.org/10.3390/en13112726.
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This paper evaluates the liquid water at the gas diffusion layer-channel (GDL-channel) interface of reconstructed GDL microstructures with uniform and non-uniform fiber diameters in wave-like channels. A non-uniform GDL microstructure is reconstructed for the first time at the GDL-channel interface to evaluate droplet motion. The three-layer GDL microstructures are generated using the stochastic technique and implemented using the OpenFOAM computational fluid dynamics (CFD) software (OpenFOAM-6, OpenFOAM Foundation Ltd., London, UK). The present study considers the relationship between reconstructed GDL surfaces with varying fiber diameters, wettability, superficial inlet velocity and droplet size. Results show that the droplet detachment and the average droplet velocity decrease with an increase in the fiber diameter as well as the structural arrangement of the fibers. Under the non-uniform fiber arrangement, the removal rate of water droplets is not significantly improved. However, the choice of smaller fiber diameters facilitates the transport of droplets, as hydrophobicity increases even at slight surface roughness. The results also indicate that the average droplet velocity decreases under low inlet velocity conditions while increasing under high inlet velocity conditions. Therefore, the structural make-up of the GDL-channel interface influences the droplet dynamics, and the implementation of a non-uniform GDL structure should also be considered in the GDL designs.
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Vynnycky, M., und A. Gordon. „On the hydrophobicity and hydrophilicity of the cathode gas diffusion layer in a polymer electrolyte fuel cell“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 469, Nr. 2154 (08.06.2013): 20120695. http://dx.doi.org/10.1098/rspa.2012.0695.
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An anomaly in the modelling of two-phase flow in the porous cathode gas diffusion layer (GDL) of a polymer electrolyte fuel cell is investigated asymptotically and numerically. Although not commented on previously in literature, the generalized Darcy model used most commonly leads to the surprising prediction that a hydrophilic GDL can lead to better cell performance, in terms of current density, than a hydrophobic one. By analysing a reduced one-dimensional steady-state model and identifying the capillary number as a small dimensionless parameter, we find a potential flaw in the original model, associated with the constitutive relation linking the capillary pressure and the pressures of the wetting and non-wetting phases. Correcting this, we find that, whereas a hydrophilic GDL can sustain a two-phase (gas/liquid) region near the water-producing catalytic layer and gas phase only region further away, a hydrophobic GDL cannot; furthermore, hydrophobic GDLs are found to lead to better cell performance than hydrophilic GDLs, as is indeed experimentally the case.
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Edjokola, Joel Mata, Viktor Hacker und Merit Bodner. „Investigation of Gas Diffusion Layer Degradation in Polymer Electrolyte Fuel Cell Via Chemical Oxidation“. ECS Meeting Abstracts MA2023-02, Nr. 38 (22.12.2023): 1871. http://dx.doi.org/10.1149/ma2023-02381871mtgabs.
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The gas diffusion layer (GDL) is a key part of the membrane electrolyte assembly and is critical for the transport of fuel, oxygen and water. The GDL is made up of two layers: macroporous substrate (MPS) and microporous layer (MPL) (1). To achieve the hydrophobicity required for water management, the two layers are typically treated with polytetrafluoroethylene (PTFE) (2). In many long-term experiments, it has been observed that GDL degradation, such as carbon corrosion and PTFE loss, leads to a deterioration of water management, conductivity and mass transport (3).To solve this durability problem, a thorough and in-depth understanding of the GDL degradation mechanism is required. In this study, GDLs are subjected to an accelerated stress test to investigate degradation by chemical oxidation. GDLs are soaked in Fenton's reagent for 24 hours. The hydrophobic properties of pristine and soaked GDLs are compared based on contact angle measurements, thermogravimetry and scanning electron microscopy. In addition, the chemical composition of the solutions before and after the immersion test is analyzed using a total organic carbon analyzer and an ion chromatograph. The results show that the hydrophobicity of GDL exposed to Fenton reagent is decreased by 5 and 4 degrees for the MPL and the MPS respectively. Fig 1. depicts a decrease in surface contact angle, which is associated with surface oxidation and PTFE deterioration. Acknowledgement This research work is performed under the project AlpeDHues (AlpeDHues / FFG 889328) which is supported by the Austrian Research Promotion Agency (FFG). References C. Csoklich, R. Steim, F. Marone, T. Schmidt and F. Büchi, ACS Applied Materials & Interfaces, 13, 9908–9918 (2021). A. Ozden, S. Shahgaldi, X. Li and F. Hamdullahpur, Progress in Energy and Combustion Science, 74, 50–102 (2019). Y. Yang, X. Zhou, B. Li and C. Zhang, Applied Energy, 303, 117688 (2021). Figure 1
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Wang, Hao, Guogang Yang, Qiuwan Shen, Shian Li, Fengmin Su, Ziheng Jiang, Jiadong Liao, Guoling Zhang und Juncai Sun. „Effects of Compression and Porosity Gradients on Two-Phase Behavior in Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells“. Membranes 13, Nr. 3 (04.03.2023): 303. http://dx.doi.org/10.3390/membranes13030303.
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Water management within the gas diffusion layer (GDL) plays an important role in the performance of the proton exchange membrane fuel cell (PEMFC) and its reliability. The compression of the gas diffusion layer during fabrication and assembly has a significant impact on the mass transport, and the porosity gradient design of the gas diffusion layer is an essential way to improve water management. In this paper, the two-dimensional lattice Boltzmann method (LBM) is applied to investigate the two-phase behavior in gas diffusion layers with different porosity gradients under compression. Compression results in an increase in flow resistance below the ribs, prompting the appearance of the flow path of liquid water below the channel, and liquid water breaks through to the channel more quickly. GDLs with linear, multilayer, and inverted V-shaped porosity distributions with an overall porosity of 0.78 are generated to evaluate the effect of porosity gradients on the liquid water transport. The liquid water saturation values within the linear and multilayer GDLs are significantly reduced compared to that of the GDL with uniform porosity, but the liquid water within the inverted V-shaped GDL accumulates in the middle region and is more likely to cause flooding.
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Hussain, Javid, Dae-Kyeom Kim, Sangmin Park, Muhammad-Waqas Khalid, Sayed-Sajid Hussain, Bin Lee, Myungsuk Song und Taek-Soo Kim. „Porous Material (Titanium Gas Diffusion Layer) in Proton Exchange Membrane Fuel Cell/Electrolyzer: Fabrication Methods & GeoDict: A Critical Review“. Materials 16, Nr. 13 (21.06.2023): 4515. http://dx.doi.org/10.3390/ma16134515.
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Proton exchange membrane fuel cell (PEMFC) is a renewable energy source rapidly approaching commercial viability. The performance is significantly affected by the transfer of fluid, charges, and heat; gas diffusion layer (GDL) is primarily concerned with the consistent transfer of these components, which are heavily influenced by the material and design. High-efficiency GDL must have excellent thermal conductivity, electrical conductivity, permeability, corrosion resistance, and high mechanical characteristics. The first step in creating a high-performance GDL is selecting the appropriate material. Therefore, titanium is a suitable substitute for steel or carbon due to its high strength-to-weight and superior corrosion resistance. The second crucial parameter is the fabrication method that governs all the properties. This review seeks to comprehend numerous fabrication methods such as tape casting, 3D printing, freeze casting, phase separation technique, and lithography, along with the porosity controller in each process such as partial sintering, input design, ice structure, pore agent, etching time, and mask width. Moreover, other GDL properties are being studied, including microstructure and morphology. In the future, GeoDict simulation is highly recommended for optimizing various GDL properties, as it is frequently used for other porous materials. The approach can save time and energy compared to intensive experimental work.
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Liu, Chang, und Shang Li. „Performance Enhancement of Proton Exchange Membrane Fuel Cell through Carbon Nanofibers Grown In Situ on Carbon Paper“. Molecules 28, Nr. 6 (20.03.2023): 2810. http://dx.doi.org/10.3390/molecules28062810.
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We developed an integrated gas diffusion layer (GDL) for proton exchange membrane (PEM) fuel cells by growing carbon nanofibers (CNFs) in situ on carbon paper via the electro-polymerization of polyaniline (PANI) on carbon paper followed by a subsequent carbonization treatment process. The CNF/carbon paper showed a microporous structure and a significantly increased pore volume compared to commercial carbon paper. By utilizing this CNF/carbon paper in a PEM fuel cell, it was found that the cell with CNF/carbon paper had superior performance compared to the commercial GDL at both high and low humidity conditions, and its power density was as high as 1.21 W cm−2 at 100% relative humidity, which is 26% higher than that of a conventional gas diffusion layer (0.9 W cm−2). The significant performance enhancement was attributed to a higher pore volume and porosity of the CNF/carbon paper, which improved gas diffusion in the GDL. In addition, the superior performance of the cell with CNF/carbon paper at low relative humidity demonstrated that it had better water retention than the commercial GDL. This study provides a novel and facile method for the surface modification of GDLs to improve the performance of PEM fuel cells. The CNF/carbon paper with a microporous structure has suitable hydrophobicity and lower through-plane resistance, which makes it promising as an advanced substrate for GDLs in fuel cell applications.
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Cremers, Carsten. „Relevance of GDL Properties Regarding GDL Quality Assurance“. ECS Meeting Abstracts MA2023-02, Nr. 38 (22.12.2023): 1872. http://dx.doi.org/10.1149/ma2023-02381872mtgabs.
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Gas diffusion layers are an important part of all types of polymer electrolyte membrane fuel cells (LT-PEMFC, HT-PEMFC or AEMFC). Albeit the conversion reaction is not taking place in the GDL the contributions of the GDL to the function of the cell are essential. So, the GDL needs to homogenise the distribution of reacting gases over the electrode area compensating inhomogeneities created by the channel fin structure of the flow-field of the bipolar plate and at the same time cause a focussing of product streams towards the channels. The GDL needs to conduct electric current between the catalyst layer and the bipolar plate at high current density and transport released thermal energy. The GDL also needs to distribute mechanical pressure of the stack compression. In order to accomplish all those tasks, the GDL needs to feature the right properties with high homogeneity through-out its area and with high reproducibility batch to batch. Unfortunately, a rather high number of properties can be assigned to a GDL. So, the review paper by Yuan et al. on properties for different LT-PEMFC components1 lists about 15 different properties for GDL which influence their function. As many of these properties are difficult to measure measuring all of them is not a viable approach to the quality assurance of GDL as part of their industrial production. Within the project QM-GDL Fraunhofer ICT together with the other partners of the project is analysing the relevance of the different properties, comparing the expected impact of deviation from the designed values and the effort, and determining the actual values. The goal is to determine the most relevant parameters which will allow to assure proper functioning of the GDL if their values are controlled keeping the effort for measurements at a reasonable value. In the presentation the approach for the selection of relevant parameters will be explained at a number of examples. Also, a tentative list of parameters will be presented and discussed. The presented work is part of the project QM-GDL which receives financial support by the German Federal Ministry of Digital Infrastructures and Traffic under Grant Agreement 03B11016E. The content of the presentation is in the sole responsibility of the author. X.-Z. Yuan, C. Nayoze-Coynel, N. Shaigan, D. Fisher, N. Zhao, N. Zamel, P. Gazdzicki, M. Ulsh, K. A. Friedrich, F. Girard and U. Groos, Journal of Power Sources, 491 (2021).