Realistic accelerated stress tests for PEM fuel cells: Test procedure development based on standardized automotive driving cycles
Paul Thiele, Yue Yang, Steffen Dirkes, Maximilian Wick, Stefan Pischinger
Abstract
A realistic accelerated stress test (AST) was derived by applying the worldwide harmonized light vehicles test cycle on a proton exchange membrane fuel cell (PEMFC) electric vehicle to analyze degradation mechanisms in fuel cells used in automotive applications. Two commercial PEMFC stacks were tested using the AST profile at different air inlet relative humidities (50% and 70%). After 173.5 h, the tested cells show degradation rates of up to 452 μV h−1 (after 147.5 h 247 μV h−1 for the second stack) at 1.0 A cm−2. Neither open circuit voltage nor high frequency resistance clearly indicate membrane degradation. Increased activation overpotential and mass transport resistance are observed, likely caused by Pt dissolution and/or agglomeration, carbon corrosion and PTFE loss. No significant correlation between air humidity and degradation is observed. The results show the method's ability to accelerate degradation while improving the result transferability of ASTs to real applications. It is adaptable and therefore applicable for other cycles and applications.