The effect of catalyst ink formulations and slot-die coating parameters on PEMFC GDE fabrication

Next Energy Pub Date : 2025-06-23 DOI:10.1016/j.nxener.2025.100334

Cecil Felix, Iosif Vazirgiantzikis, Mphoma Matseke, Olivia Barron, Mpfunzeni Raphulu

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Abstract

Slot-die coating is a promising method for mass-producing membrane electrode assemblies for polymer electrolyte membrane fuel cells. Precise control of slot-die coating parameters and catalyst ink variables is essential for achieving defect-free catalyst layers. This study investigated catalyst ink rheology and coating windows of typical ink formulations and extremes. The influence of the dispersing solvent ratio, ionomer-to-carbon ratio, and Pt weight percentage on catalyst ink rheology and coating behaviour was examined. Inks with a 75%-water/25%-n-propanol dispersing solvent ratio exhibited shear-thinning and good coatability, while those with high water content (90%-water/10%-n-propanol) displayed Newtonian flow, leading to poor substrate wetting and coating. Increasing the ionomer-to-carbon ratio reduced the ink's viscosity, while increasing the Pt weight percentage increased the ink’s viscosity. While appearing defect-free, x-ray fluorescence and optical microscopy analyses revealed that the coated catalyst layers often displayed nonuniform Pt loadings and cracks, especially with increasing catalyst layer thickness. The nonuniform Pt loadings were attributed to variations in gas diffusion layer roughness, catalyst layer cracks, and limitations of the slot-die coater. Initial membrane electrode assembly performance tests underscored the importance of material selection, the ionomer overlayer, and hot-pressing to enhance performance.

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催化剂油墨配方和槽模涂层参数对PEMFC GDE制备的影响

槽模涂覆是一种很有前途的大规模生产聚合物电解质膜燃料电池膜电极组件的方法。精确控制槽模涂层参数和催化剂油墨变量对于实现无缺陷催化剂层至关重要。本研究考察了典型油墨配方和极值的催化剂油墨流变性和涂层窗口。考察了分散溶剂比、离碳比和Pt质量百分比对催化剂油墨流变性和涂层性能的影响。当溶剂配比为75%-水/25%-正丙醇时，油墨表现出剪切减薄性和良好的涂布性，而当溶剂配比为90%-水/10%-正丙醇时，油墨表现出牛顿流动，导致基材润湿性和涂布性较差。增加离碳比降低了油墨的粘度，而增加铂的重量百分比则增加了油墨的粘度。虽然表面上没有缺陷，但x射线荧光和光学显微镜分析显示，涂层的催化剂层经常出现不均匀的铂负载和裂纹，特别是随着催化剂层厚度的增加。不均匀的铂负载归因于气体扩散层粗糙度的变化、催化剂层裂纹和槽模涂布机的局限性。最初的膜电极组装性能测试强调了材料选择、离子层和热压的重要性，以提高性能。

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Next Energy

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