Polymer electrolyte membrane fuel cells (PEMFCs) are a good candidate for fuel cell electric vehicles (FCEVs) due to their high efficiency, high power density and zero-emission. However, the lifetime is one of the main barriers to overcome before their commercialization. The durability testing methods for PEMFCs are main include electrocatalyst cycle, catalyst support cycle, membrane electrode assembly (MEA) chemical stability, membrane mechanical cycle and so on. In addition, there is little research about MEA chemical stability test, which applies a continuous open-circuit voltage (OCV) to produce more free radicals and these will have a bad influence on PEMFCs. Based on this, the durability of PEMFC was studied under OCV operation at 30% relative humidity (RH), 90 °C and 150 kPa inlet pressure. The electrochemical performances such as in-situ cyclic voltammetry (CV), linear sweep voltage (LSV) and cell polarization were used to evaluate the durability of PEMFC. Scanning electron microscopy (SEM) was applied to identify the degradation of polymer electrolyte membrane (PEM). After 168 h of durability test, the open circuit voltage decreases from 0.96 to 0.8 V, the maximum power density decreases from 795 to 470 mW cm-2 and the current densities exceed or close to 15 mA cm-2. Apart from this, the reduction in thickness of PEM is 4 μm. These results indicate that the free radicals, which are produced during the OCV test can degradation the ionomer and cause thinning PEM. Eventually lead to bad electrochemical performance and poor lifetime of PEMFCs. Therefore, it is necessary to develop free-radical scavengers to improve the durability of the PEMFCs.
展开▼
机译：聚合物电解质膜燃料电池（PEMFC）是燃料电池电动车（FCEV）的良好候选者，由于其高效率，高功率密度和零排放。然而，寿命是在商业化之前克服的主要障碍之一。 PEMFCs的耐久性测试方法是主要的，包括电催化剂循环，催化剂支撑循环，膜电极组件（MEA）化学稳定性，膜机械循环等。此外，还有大约是MEA的化学稳定性测试，适用于连续的开路电压（OCV），以产生更多的自由基，这些都会对PEMFC的不好的影响的研究很少。基于此，在30％相对湿度（RH），90°C和150kPa入口压力下在OCV操作下研究了PEMFC的耐久性。使用诸如原位循环伏安法（CV），线性扫描电压（LSV）和电池偏振的电化学性能来评估PEMFC的耐久性。施用扫描电子显微镜（SEM）以鉴定聚合物电解质膜（PEM）的降解。在耐用性测试的168小时之后，开路电压从0.96降低至0.8V，最大功率密度从795降低到470 mW cm-2，电流密度超过15 mA cm-2。除此之外，PEM的厚度的降低为4μm。这些结果表明，在OCV测试期间产生的自由基可以降解离聚物并导致稀释PEM。最终导致了不良的电化学性能和PEMFC的寿命不佳。因此，有必要开发自由基清除剂以改善PEMFC的耐久性。
展开▼
