Empirical modeling of cathode electrode durability in polymer electrolyte fuel cells

The cathode electrode (CE) is a key component of polymer electrolyte fuel cells considering both performance and durability. The CE degrades under normal operating conditions due to load cycles and start/stop cycles via platinum and carbon support degradation mechanisms, respectively. In this study CE degradation from both types of cycles is modeled using data from experimental accelerated stress tests. It is shown that any interaction effects from superposition of the two types of cycles are negligible. This suggests that carbon corrosion effects are independent of platinum dissolution/agglomeration. The effect of the lower potential limit applied during load cycling is also shown to be negligible for 0.6 V-0.8 V, given a fixed upper potential limit. In addition, empirical fuel cell performance data is used with a simple vehicle model to convert standard drive cycles to fuel cell load cycles. Finally, a methodology is proposed to count equivalent voltage cycles from voltage profiles to link the accelerated test data to realistic operating conditions. The model is used to make CE durability predictions (to 10% voltage loss) under different drive cycle conditions to compare against fuel cell stack durability data for field operation of fuel cell vehicles.