The Impact of Potential Cycling on PEMFC Durability

Voltage cycling is one of the most damaging stressors for automotive PEMFC. Understanding of the effects of voltage cycling on performance degradation is crucial to improve PEMFC durability for automotive applications. This study focuses on the interaction between upper potential limit (UPL) and lower potential limit (LPL) on the stability of PEMFC. A well-defined peak of degradation rate is observed when the LPL is ∼0.8 V with UPL of 1.35 V. A mathematical model was developed to understand the observed relationship between degradation rate and lower potential. Modeling results suggest that when cycling to a lower potential of ∼0.8 V, almost all dissolved Pt migrate from the catalyst layer to the membrane with negligible re-deposition, resulting in a peak of degradation rate at ∼0.8 V. The amount of Pt in the membrane (PITM) measured at end of life (EOL) samples correlates with degradation rates and is in agreement with modeling results.