Kim Beom-Seok, Park Jong-Hyeok, Park Jin-Soo
Department of Green Chemical Engineering, College of Engineering, Sangmyung University, Cheonan 31066, Republic of Korea.
Department of Civil, Environmental and Biomedical Engineering, The Graduate School, Sangmyung University, Cheonan 31066, Republic of Korea.
Membranes (Basel). 2023 Sep 13;13(9):794. doi: 10.3390/membranes13090794.
In this study, blended perfluorinated sulfonic acid (PFSA) ionomers with equivalent weights (EWs, g/mol) of ~1000, 980, and 830 are prepared. Catalyst layers (CLs), using blended PFSA ionomers, with different side chain lengths and EWs are investigated and compared to CLs using single ionomers. The ion exchange capacity results confirm that blended ionomers have the target EWs. As a result, blended ionomers exhibit higher ion conductivity than single ionomers at all temperatures due to the higher water uptake of the blended ionomers. This implies that blended ionomers have a bulk structure to form a competent free volume compared to single ionomers. Blended ionomers with short side chains and low EWs can help reduce the activation energy in proton conduction due to enhanced hydrophobic and hydrophilic segregation. In addition, when using the blended ionomer, the CLs form a more porous microstructure to help reduce the resistance of oxygen transport and contributes to lower mass transfer loss. This effect is proven in fuel cell operations at not a lower temperature (70 °C) and full humidification (100%) but at an elevated temperature (80 °C) and lower relative humidity (50 and 75%). Blended ionomer-based CLs with a higher water uptake and porous CL structure result in improved fuel cell performance with better mass transport than single ionomer-based CLs.
在本研究中，制备了等效重量（EWs，g/mol）约为1000、980和830的共混全氟磺酸（PFSA）离聚物。研究了使用具有不同侧链长度和EWs的共混PFSA离聚物的催化剂层（CLs），并与使用单一离聚物的CLs进行了比较。离子交换容量结果证实共混离聚物具有目标EWs。结果，由于共混离聚物的吸水率较高，共混离聚物在所有温度下都表现出比单一离聚物更高的离子电导率。这意味着与单一离聚物相比，共混离聚物具有形成合适自由体积的本体结构。具有短侧链和低EWs的共混离聚物由于增强的疏水和亲水分离作用，有助于降低质子传导中的活化能。此外，当使用共混离聚物时，CLs形成更多孔的微观结构，有助于降低氧传输阻力并减少传质损失。这种效果在燃料电池运行中得到了证明，不是在较低温度（70°C）和全湿度（100%）下，而是在较高温度（80°C）和较低相对湿度（50%和75%）下。具有较高吸水率和多孔CL结构的基于共混离聚物的CLs比基于单一离聚物的CLs具有更好的传质性能，从而提高了燃料电池性能。
