Effect of humidity and thermal cycling on the catalyst layer structural changes in polymer electrolyte membrane fuel cells
Effect of humidity and thermal cycling on the catalyst layer structural changes in polymer electrolyte membrane fuel cells
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湿度和热循环对聚合物电解质膜燃料电池催化剂层结构变化的影响
DOI：
10.1016/j.enconman.2019.03.066
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发表时间：
2019-06-01
影响因子：
10.4
通讯作者：
Li, Xianguo
中科院分区：
文献类型：
--
作者：
Chang, Yafei;Liu, Jing;Li, Xianguo
聚合物电解质膜燃料电池中催化剂层结构的变化对电池的性能和耐久性有重要影响。在这项研究中，异位实验的目的是调查的影响，湿度和/或热循环的催化剂层的结构变化。通过环境室控制相对湿度和温度，并通过扫描电子显微镜和光学显微镜表征催化剂层结构。实验结果表明，催化剂层的主要结构变化是裂纹的生长和发展、催化剂团聚体的脱落和表面的凸起。同时施加相对湿度和热循环导致最显著的裂纹生长，而单独施加热循环不会引起明显的变化。这表明，绝对湿度是裂纹扩展的关键参数。循环伏安分析表明，经过500次湿热循环后，其电化学活性表面积从64.1m2·g-1下降到49.1m2·g-1。电化学阻抗谱分析表明，经过500次湿热循环后，电池的电荷转移电阻和欧姆电阻显著增加，电池性能下降。
Catalyst layer structural changes in polymer electrolyte membrane fuel cells have significant impact on the cell performance and durability. In this study, ex-situ experiments are designed to investigate the effect of humidity and/or thermal cycles on the structural changes of catalyst layers. The relative humidity and temperature are controlled by an environmental chamber and the catalyst layer structure is characterized by scanning electron microscopy and optical microscopy. The experimental results indicate that crack growth and development, catalyst agglomerate detachment, and surface bulges are the main structural changes of the catalyst layers. Applying relative humidity and thermal cycling simultaneously causes the most significant crack growth, while applying thermal cycling alone causes no appreciable changes. This indicates that the absolute humidity is the key parameter for the crack growth. Through cyclic voltammetry analysis, it is shown that the electrochemical active surface area decreases from 64.1 m(2) g(-1) to 49.1 m(2) g(-1) after 500 combined relative humidity and thermal cycles. Analyses of electrochemical impedance spectroscopy show that the charge transfer resistance and ohmic resistance increase significantly after 500 combined relative humidity and thermal cycles, causing the cell performance degradation.