Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4 Takeda, Kofu 400-8510, Japan.
ACS Appl Mater Interfaces. 2012 Feb;4(2):730-7. doi: 10.1021/am201360j. Epub 2012 Jan 17.
Sulfonated polyimide (SPI-8) ionomers were used as binders in the catalyst layers, and their fuel cell performance was evaluated. SPI-8 ionomers functioned well in the anode with only minor overpotential even at low humidity (50% relative humidity (RH)). In contrast, the cathode performance was significantly dependent on the content and molecular weight of the ionomers and humidity of the supplied gases. Higher molecular weight of the ionomer caused larger potential drop at high current density at 80 and 100% RH since oxygen supply and/or water discharge became insufficient due to higher water uptake (swelling) of the ionomer. Similar results were obtained at higher ionomer content, because of the increase of thickness in the catalyst layer. The mass transport was improved with decreasing humidity, however, proton conductivity became lower. While the maximum values of j(@0.70 V) for all membrane electrode assemblies (MEAs) were ca. 0.35 A/cm(2), each electrode could have the different appropriate operating conditions. The results suggest that the parameters such as oxygen supply, proton conductivity, and water uptake and discharge need to be carefully optimized in the catalyst layers for achieving reasonable cathode performance with hydrocarbon ionomers.
磺化聚酰亚胺（SPI-8）离子聚合物被用作催化剂层中的粘结剂，并评估了其燃料电池性能。SPI-8 离子聚合物在阳极中表现良好，即使在低湿度（50%相对湿度（RH））下，其过电势也很小。相比之下，阴极性能严重依赖于离子聚合物的含量和分子量以及供应气体的湿度。由于离子聚合物的吸水量（溶胀）增加，导致在 80%和 100%RH 时高电流密度下的电位降更大，因此高分子量的离子聚合物会导致更大的电位降。在更高的离子聚合物含量下，也会出现类似的结果，因为催化剂层的厚度增加了。随着湿度的降低，质量传输得到改善，但是质子电导率会降低。虽然所有膜电极组件（MEA）在 0.70 V 时的 j（@0.70 V）最大值约为 0.35 A/cm(2)，但每个电极都可以有不同的适当工作条件。结果表明，需要在催化剂层中仔细优化诸如氧气供应、质子电导率以及水的吸收和排放等参数，以实现使用烃类离子聚合物的合理阴极性能。
