Investigation of the reversible performance degradation mechanism of the PEMFC stack during long-term durability test

This paper reports on 3-cell PEMFC stack durability test of 2500 h in dynamic conditions and different recovery procedures. After electrochemical impedance spectroscopy (EIS) analysis, it was determined that the primary cause of the stack performance degradation is the oxidation of platinum (Pt), which is reversible. The air starvation operation reduced the cathode voltage to less than 0.2 V, part of PtO was reduced, and the stack performance loss was partially recovered. However, the recovery of the three cells varies due to defects in the three-cell stack and uneven gas distribution. The fast load-up operation brought the short-term severe air starvation of the three cells to a similar level, the remaining platinum oxide (PtO) was fully reduced, the stack performance improved again, and the voltage consistency of the three cells was restored significantly. With the optimization of operating parameters and combined recovery procedures, the average degradation rate of the stack voltage is 3.08 μV/h within 2500 h. The results indicated that our combined strategy is of huge importance to mitigate the reversible performance degradation and significantly extend the service life of PEMFC stack and be a very appropriate procedure used in laboratories and systems.