Realistic accelerated stress tests for PEM fuel cells: Validation of load profile optimization via lifetime prognosis in fuel cell electric vehicles

Polymer electrolyte membrane fuel cells are one promising option towards an emission-free energy market, especially for the mobility sector. However, their limited lifetime is still a challenge for establishing them in the market. Since lifetimes of several thousand hours are targeted for mobile applications, accelerated stress tests (ASTs) must be used to analyze degradation phenomena and take preventive measures. The results of such ASTs are only partially transferable to reality, which is why the development of realistic ASTs (rASTs) is necessary. This work builds on previous publications dealing with the derivation of rASTs from standardized automotive driving cycles and the optimization of such rASTs regarding test duration by eliminating phases that do not promote degradation. An optimization method is developed for the published AST algorithm to automatically determine the optimal parameters regardless of the investigated application and cycle. A degradation model is used to predict the lifetime in a semi-empirical manner to ensure that no significant differences occur between the degradation caused by the initial driving cycles and the rASTs. Two commercially available stacks (the stack used in the Toyota Mirai 1 and a short-stack) are used to calibrate the model, and two passenger car applications are analyzed to validate the robustness of the methodology. The results show that the AST algorithm can reduce the cycle duration for each application case by at least 51% while the relative lifetime deviation stays below 10%. Therefore, the AST algorithm can consistently and robustly generate rASTs for automotive applications regardless of the investigated vehicle. • Robust and consistent validation of AST algorithm for various stacks and use cases. • Method to generate realistic ASTs regardless of the investigated automotive application. • Lifetime prognosis of PEM fuel cells in automotive applications.