Development of Accelerated Durability Test Protocols for Polymer Electrolyte Membrane Fuel Cell Stacks Under Realistic Operating Conditions

Abstract

Polymer electrolyte membrane fuel cell durability is still a major challenge. To overcome time-consuming durability tests, so-called accelerated durability tests (ADTs) are of urgent need. This work presents our recent results in developing ADT protocols in the context of realistic operating conditions, especially voltage clipping at 0.85 V. A 5500 h long-term test was carried out as a 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 1200 h duration were derived. Seven-cell short stacks with 240 cm² active area were used. Comparing cell voltage as a key indicator, an acceleration factor of 3–7 could be achieved. In-situ characterization techniques such as spatially resolved current measurement, cyclic voltammetry, and electrochemical impedance spectra were employed to investigate the influences of individual stressors on specific degradation mechanisms and components. The highest acceleration was observed in the mass transport region of ADTs addressing RH as a 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 a homogeneous acceleration of voltage degradation across all current regions.