Ma Jun, Ma Hualong, Lin Jiayi, Zhang Yixiao, Xiao Li, Zhuang Lin, Xu Pengtao, Chen Liwei
School of Chemistry and Chemical Engineering, In situ Center for Physical Sciences, Shanghai Electrochemical Energy Device Research Center (SEED), Global Institute of Future Technology, Shanghai Jiao Tong University Shanghai 200240 China
Hubei Key Lab of Electrochemical Power Sources, College of Chemistry and Molecular Sciences, Wuhan University Wuhan 430072 China.
RSC Adv. 2024 Aug 23;14(37):26738-26746. doi: 10.1039/d4ra04019h. eCollection 2024 Aug 22.
Alkaline polymer electrolyte fuel cells (APEFCs) have achieved notable advancements in peak power density, yet their durability during long-term operation remains a significant challenge. It has been recognized that increasing the hydrophobicity of the catalyst layer can effectively alleviate the performance degradation. However, a microscopic view of how hydrophobicity contributes to the stability of the catalyst layer microstructure is not clear. Here, we construct a membrane electrode assembly (MEA) with enhanced structural stability and durability by incorporating polytetrafluoroethylene (PTFE) particles into the catalyst layer. MEAs modified by this approach exhibit stabilized voltage platforms in current step tests and reduced hysteresis in current-voltage polarization curves during operation, indicating the critical role of PTFE in the removal of the excess water within the catalyst layer. Fuel cells with PTFE modification show more than 45% increase in electrochemical durability. By characterizing with field-emission scanning electron microscopy (FE-SEM) the surface and the internal microstructures of MEAs after durability tests, we find that the catalyst layers modified by PTFE experience much less reduction in porosity and less agglomeration of the solid components. These findings elucidate the microscopic mechanisms by which hydrophobicity promotes a more stable catalyst layer structure, thereby enhancing the durability of APEFCs. This research advances our understanding of hydrophobicity's impact on catalyst layer stability and offers a practical method to enhance the durability of APEFCs.
碱性聚合物电解质燃料电池（APEFCs）在峰值功率密度方面已取得显著进展，但其长期运行期间的耐久性仍是一项重大挑战。人们已经认识到，提高催化剂层的疏水性可以有效缓解性能下降。然而，疏水性如何影响催化剂层微观结构稳定性的微观机制尚不清楚。在此，我们通过将聚四氟乙烯（PTFE）颗粒掺入催化剂层来构建具有增强结构稳定性和耐久性的膜电极组件（MEA）。通过这种方法改性的MEA在电流阶跃测试中表现出稳定的电压平台，并且在运行期间电流-电压极化曲线中的滞后减小，这表明PTFE在去除催化剂层内多余水分方面的关键作用。经过PTFE改性的燃料电池在电化学耐久性方面提高了45%以上。通过用场发射扫描电子显微镜（FE-SEM）对耐久性测试后的MEA表面和内部微观结构进行表征，我们发现经PTFE改性的催化剂层孔隙率降低较少，固体成分团聚较少。这些发现阐明了疏水性促进更稳定催化剂层结构的微观机制，从而提高了APEFCs的耐久性。这项研究增进了我们对疏水性对催化剂层稳定性影响的理解，并提供了一种提高APEFCs耐久性的实用方法。
