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Anode aging in polymer electrolyte membrane fuel Cells I: Anode monitoring by ElectroChemical impedance spectroscopy
Journal of Power Sources ( IF 9.2 ) Pub Date : 2020-09-12 , DOI: 10.1016/j.jpowsour.2020.228908
Salah Touhami , Laetitia Dubau , Julia Mainka , Jérôme Dillet , Marian Chatenet , Olivier Lottin

Degradation of polymer electrolyte membrane fuel cells (PEMFC) is investigated through an accelerated stress test (AST) consisting of load-induced humidity cycling combined with open circuit voltage. This combined stressor-AST was designed to mimic real operating conditions. Commercially available membrane-electrode assemblies with an initial voltage of about 0.7 V at 0.5 A cm−2 showed a performance drop of about 900 μV h−1. Their operation was followed by monitoring various parameters such as polarization plots, electrode electrochemical surface area, hydrogen permeation and electrochemical impedance spectra. The results demonstrate that, although initially, the anode may be ignored to model the impedance data, this is no longer possible during the AST. Experimental data show that, beyond classical cathode and membrane degradations, the cell undergoes pronounced anode degradations, that significantly affect the cell performances. Local potential measurements excluded the anode degradation to be linked to electrode potential cycling, the latter remaining always between 0 and 0.2 V vs reference hydrogen electrode. Classical mechanisms of Pt/C degradation may thus not be at stake here, but rather mechanical destabilization of the anode microstructure under wet-dry cycling. The temperature elevation at high current density, known to entail local membrane dehydration may be an aggravating factor.



中文翻译:

聚合物电解质膜燃料电池中的阳极老化I:通过电化学阻抗谱监测阳极

通过加速应力测试(AST)研究了聚合物电解质膜燃料电池(PEMFC)的降解,该测试由负载引起的湿度循环和开路电压组成。这种组合的Stressor-AST旨在模拟真实的工作条件。市售的膜电极组件在0.5 A cm -2时的初始电压约为0.7 V,表现出约900μVh -1的性能下降。在他们的操作之后,监视各种参数,例如极化图,电极电化学表面积,氢渗透和电化学阻抗谱。结果表明,尽管最初可以忽略阳极来模拟阻抗数据,但在AST期间不再可能。实验数据表明,除了经典的阴极和膜降解之外,电池还经历了明显的阳极降解,这严重影响了电池的性能。局部电势测量排除了与电极电势循环有关的阳极退化,与基准氢电极相比,后者始终保持在0至0.2 V之间。因此,此处可能不会危及Pt / C降解的经典机制,而是在干湿循环下阳极微结构的机械失稳。高电流密度下的高温升高(已知会引起局部膜脱水)可能是一个加剧的因素。

更新日期:2020-09-12
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