New insights into the performance and durability degradation mechanisms of PEMFCs caused by Cr3+contaminant

It is known that contamination ions stemming from the corrosive deterioration of vital subassemblies, such as bipolar plates (BPs) and sealing gaskets, exert a profound influence on the performance and durability degradation of PEM fuel cells. The impacts of Cr3+ on the catalyst layers (CLs) and single-cell performance were investigated by immersing the cathode catalyst layer (CCL) and anode catalyst layer (ACL) in a Cr3+ solution with different concentrations for contamination treatment. During the fuel cell test, polarization curves (PCs), electrochemical impedance spectroscopy (EIS), H+ transfer impedance, and cyclic voltammetry (CV) curve results were recorded. The effects of Cr3+ contamination on the kinetic for oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) were analyzed in a three-electrode system. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to explore the degradation mechanisms of Cr3+ contamination on fuel cell activity. The results indicate that the presence of Cr3+ increased the ohmic impedance from 0.200 omega cm2 to 0.449 omega cm2, resulting in a voltage attenuation rate as high as 55.21 %. Moreover, the presence of Cr3+ slowed the ORR reaction rate and changed the ORR reaction pathway. Cr3+ contamination caused irreversible damage to PEMFC performance and durability.