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首页> 外文期刊>ACS Macro Letters >Submicrometer 3D Structural Evidence of Fuel Cell Membrane Heterogeneous Degradation
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Submicrometer 3D Structural Evidence of Fuel Cell Membrane Heterogeneous Degradation

机译：燃料电池膜异质降解的亚微米3D结构证据

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摘要

Polymer membranes used in the proton exchange membrane fuel cell (PEMFC) technology are subject to severe chemical and physical degradations during operation. A microscopic diagnosis of the effects of aging on the microstructure of benchmark perfluorinated sulfonic acid (PFSA) membranes is crucial to developing long- lasting devices. We report here the first μSAXS study of membranes aged for 2500 h in a stack. SAXS spectra recorded with submicrometer resolution in-plane and along the membrane thickness provide a 3D mapping of the aging effect. Nanoscale heterogeneities are evidenced and found to depend on the membrane position relative to the electrodes, to the air inlets, and proximity to channels (distributing gas) or ribs (collecting the current). Long-term aging in a fuel cell operating in stationary conditions around 65 °C results in a small voltage degradation rate of 13 μV/h, without any evidence of membrane failure, but to an irreversible over-swelling of the membrane due to polymer relaxation. Regions under the gas distribution channels close to the air inlet are profoundly degraded due to an increased water gradient concentration from the cathode to the anode. These observations provide a novel and unique insight for developing new strategies toward the design of more durable polymers inserted in smart fuel cells.
机译：质子交换膜燃料电池（PEMFC）技术中使用的聚合物膜在操作过程中会遭受严重的化学和物理降解。对老化对基准全氟化磺酸（PFSA）膜的微观结构的影响进行微观诊断对于开发耐用的设备至关重要。我们在这里报告了堆叠中老化2500 h的膜的首次μSAXS研究。以面内和沿膜厚度的亚微米分辨率记录的SAXS光谱提供了老化效果的3D映射。纳米级的异质性得到了证明，并被发现取决于相对于电极，进气口以及与通道（分布气体）或肋（收集电流）的接近程度。在约65°C的静态条件下运行的燃料电池的长期老化会导致13μV/ h的小电压降级速度，没有任何膜破裂的迹象，但由于聚合物松弛而导致的膜不可逆转的过度膨胀。由于从阴极到阳极的水梯度浓度增加，气体分配通道下方靠近进气口的区域严重退化。这些观察结果为开发新策略提供了新颖独特的见解，从而可以设计出插入智能燃料电池中的更耐用的聚合物。

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