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The threshold method in the analysis of catalyst layer porosity towards oxygen transport resistance in PEMFCs
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2021-09-07 , DOI: 10.1039/d1cy00882j Xinye Sun 1, 2 , Hongmei Yu 1 , Xueqiang Gao 1, 2 , Zhigang Shao 1
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2021-09-07 , DOI: 10.1039/d1cy00882j Xinye Sun 1, 2 , Hongmei Yu 1 , Xueqiang Gao 1, 2 , Zhigang Shao 1
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The threshold method is introduced to characterize the porosity of a catalyst layer in this work on the basis of the impact analysis of the ionomer content on oxygen transport resistance. The limiting current method is used to measure the transport resistance of fuel cells with various ionomer content levels. The results show that increasing the ionomer content, especially I/C > 0.7, can cause the enlargement of Fickian resistance and local transport resistance. The increase in local oxygen transport resistance is attributed to the thickening of the ultra-thin ionomer film and the improvement of the ionomer coverage degree at the surface of the Pt particles. The decrease in porosity in the catalyst layer caused by the blocking effect of the ionomer is considered to be the reason for the enlargement of the Fickian resistance. However, according to published work, the measurement of the catalyst layer porosity is limited, especially in situ characterization. Here, the threshold method is applied to characterize the porosity in situ through the calculation of the saturated water content in the fuel cell, since water accumulates via capillarity in the pore structure of the catalyst layer. The characterization results are highly consistent with the trend of the Fickian diffusion coefficient, which verifies the availability of the threshold method for the in situ measurement of porosity in catalyst layers.
中文翻译：
催化剂层孔隙率对 PEMFC 中氧传输阻力的阈值分析
本工作基于离聚物含量对氧传输阻力的影响分析，引入阈值法表征催化剂层的孔隙率。极限电流法用于测量各种离聚物含量水平的燃料电池的传输电阻。结果表明，增加离聚物含量，尤其是I/C>0.7，会导致Fickian阻力和局部输运阻力增大。局部氧传输阻力的增加归因于超薄离聚物薄膜的增厚和Pt颗粒表面离聚物覆盖度的提高。离聚物的阻塞效应引起的催化剂层孔隙率的降低被认为是费克电阻增大的原因。然而，原位表征。在这里，阈值方法用于通过计算燃料电池中的饱和水含量来原位表征孔隙率，因为水通过催化剂层的孔隙结构中的毛细管作用积聚。表征结果与 Fickian 扩散系数的趋势高度一致，验证了阈值法用于原位测量催化剂层孔隙率的有效性。
更新日期：2021-09-14
中文翻译：
催化剂层孔隙率对 PEMFC 中氧传输阻力的阈值分析
本工作基于离聚物含量对氧传输阻力的影响分析，引入阈值法表征催化剂层的孔隙率。极限电流法用于测量各种离聚物含量水平的燃料电池的传输电阻。结果表明，增加离聚物含量，尤其是I/C>0.7，会导致Fickian阻力和局部输运阻力增大。局部氧传输阻力的增加归因于超薄离聚物薄膜的增厚和Pt颗粒表面离聚物覆盖度的提高。离聚物的阻塞效应引起的催化剂层孔隙率的降低被认为是费克电阻增大的原因。然而，原位表征。在这里，阈值方法用于通过计算燃料电池中的饱和水含量来原位表征孔隙率，因为水通过催化剂层的孔隙结构中的毛细管作用积聚。表征结果与 Fickian 扩散系数的趋势高度一致，验证了阈值法用于原位测量催化剂层孔隙率的有效性。
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