Abstract
The durability of polymer electrolyte fuel cells (PEFCs) in fuel cell electric vehicles (FCEVs) is important for the shift from passenger cars to heavy-duty vehicles. The components of a PEFC, namely the proton exchange membrane (PEM), catalyst layer (CL), and gas diffusion layer (GDL), contribute to the degradation of the fuel cell performance. These degradation studies were conducted independently and focused on PEMs and CLs. The degraded fuel cell stack in FCEVs is completely replaced. Therefore, it is necessary to counteract rapid material degradation in PEFCs. In this paper, we propose a method for simultaneously evaluating the degradation rates of these components by combining electrochemical characterization with operando synchrotron X-ray radiography. The open-circuit voltage, electrochemically active surface area, and water saturation were used as the degradation indicators for the PEMs, CLs, and GDLs, respectively. The results of two accelerated stress tests (loading and start-stop cycles) showed that the increase in water saturation owing to the loss of hydrophobicity due to carbon corrosion in the cathode GDL occurred on the same time scale as the degradation in the PEM and cathode CL. This suggests that more efforts should be devoted to studies on the durability of GDLs for heavy-duty applications.