PEMFC durability is still a major challenge. To overcome time-consuming durability tests, so-called accelerated durability tests (ADT) are of urgent need. This work presents our recent results in developing ADT protocols in the context of realistic operating conditions, i.e. voltage clipping at 0.85 V. A 5,500 h long-term test was carried out as reference applying a realistic automotive drive cycle. Focusing on different stressors such as temperature, relative humidity (RH) and load profile four different ADT protocols of 1,200 h duration were derived. 7-cell short stacks with 240 cm² active area were used. Comparing cell voltage as key indicator, an acceleration factor of 3 to 7 could be achieved. In situ characterization techniques such as spatially resolved current measurement, CV and EIS were employed to investigate influences of individual stressors on specific degradation mechanisms and components. Highest acceleration was observed in mass transport region of ADTs addressing RH as stressor, suggesting that RH cycling leads to increased degradation of hydrophobic surfaces. Increased temperature was found to accelerate primarily carbon support degradation. Accelerated catalyst aging seems to be low, demonstrating the effectiveness of voltage clipping conditions. Our most promising ADT shows quite homogeneous acceleration of voltage degradation across all current regions.
Schüttoff et al. (Thu,) studied this question.