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Experimental and theoretical study of a dual-layer gas diffusion layer in PEM fuel cells.

机译：PEM燃料电池中双层气体扩散层的实验和理论研究。

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The gas diffusion layer (GDL) in proton exchange membrane fuel cells (PEMFCs) functions as a diffuser and a current collector. The GDL typically consists of the microporous layer (MPL) and the macroporous substrate (MPS). The MPL reduces the ohmic losses and facilitates water removal in the MEA.;In this study, a novel method was developed to prepare a dual-layer GDL that enhances the catalyst utilization and the overall fuel cell performance. Several characterization techniques, including mercury porosimetry, water permeation measurement, electrochemical polarization and ac impedance spectroscopy were performed to investigate how carbon loading (or MPL thickness) and PTFE content in the MPL and in the MPS control the water management in PEM fuel cells.;An experimental study on carbon loading in the MPL showed that a relatively low carbon loading (0.5 mg cm-2 in this study) results in a balancing of water saturations in the catalyst layer and the GDL, thus improving the oxygen diffusion kinetics.;Experimental studies on PTFE content in the MPL and in the MPS indicated that effective water management is attributed to the trade-off between the pore volume and the hydrophobic property of each diffusion layer.;A theoretical study of a dual-layer GDL in PEM fuel cells demonstrated that saturation in the MPS is intimately coupled with both the fraction of hydrophilic surface and the average pore diameter. A thin and more hydrophobic MPL altered the pore geometry and the hydrophobic property of a MPS, resulting in better mass transport of reactants and products in the MEA.
机译：质子交换膜燃料电池（PEMFC）中的气体扩散层（GDL）充当扩散器和集电器。 GDL通常由微孔层（MPL）和大孔基质（MPS）组成。 MPL减少了欧姆损耗并促进了MEA中的水分去除。;在本研究中，开发了一种新颖的方法来制备双层GDL，该双层GDL可提高催化剂利用率和整体燃料电池性能。进行了包括汞孔隙率法，水渗透率测量，电化学极化和交流阻抗谱在内的多种表征技术，以研究MPL和MPS中的碳负载（或MPL厚度）和PTFE含量如何控制PEM燃料电池中的水管理。对MPL中碳载量的实验研究表明，相对较低的碳载量（本研究中为0.5 mg cm-2）导致催化剂层和GDL中水饱和度的平衡，从而改善了氧扩散动力学。对MPL和MPS中PTFE含量的研究表明，有效的水管理归功于每个扩散层的孔体积和疏水性之间的权衡。;对PEM燃料电池中双层GDL的理论研究证明了MPS的饱和度与亲水性表面的分数和平均孔径密切相关。较薄且疏水性更强的MPL改变了MPS的孔几何形状和疏水性，从而导致MEA中反应物和产物的质量传递更好。

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