6. Performance Degradation of PEM Fuel Cells During Startup–Shutdown Cycles: A Case Study

The chapter delves into the critical issue of performance degradation in PEMFCs during startup-shutdown cycles, a pivotal dynamic process affecting fuel cell operation. It explores the major cause of degradation, the hydrogen-air interface at the anode, and its impact on fuel cell performance. The study involves two types of PEMFCs—open-ended and closed—and investigates their performance decay under different cathode exhaust conditions and gas shutdown sequences. The chapter presents detailed experimental setups, including single-cell tests and various electrochemical techniques to characterize performance decay. Notably, it demonstrates that closed cells experience less performance degradation compared to open-ended cells, particularly at high current densities. The study also highlights the importance of gas shutdown sequences in mitigating performance loss and offers insights into the mechanisms of catalyst degradation and hydrogen crossover. By comparing different shutdown procedures, the chapter provides valuable strategies to enhance the durability and efficiency of PEMFCs during frequent startup and shutdown cycles.