Comparison of Proton Exchange Membranes Degradation Rates between Accelerated and Performance Tests

To establish a universal procedure to determine and predict the durability of components of PEM fuel cells in practical applications, it is desirable to assess the extent to which accelerated stress tests amplify cell degradation compared to lifetime tests. Experimental data from performance evaluation tests and open circuit voltage accelerated stress tests were compared to verify the ability for this type of accelerated test to provide a true measure of cell life. The performance evaluation tests involved 184 h total operation, including performance tests at 80 to 120°C and 35 to 100% RH as well as a stability test for 64 hours at 95°C/83% RH, 400 mA/cm2 and 0.5 atm backpressure. The OCV ASTs involve operation at 90°C/30% RH and OCV for 100 h. Diagnostic tests conducted on the cells included hydrogen crossover, fluoride emission, catalyst electrochemical surface area, post-test membrane SEM and TEM evaluation, and defect identification in membranes. In general, the ASTs resulted in accelerated decay modes. The relationship between the deterioration during the performance tests and the ASTs was found to be a function of the Pt/C and PtCo/C electrode catalysts and different electrode ionomer types (1100 EW Nafion and 825 EW 3M) used.