Experimental study on the effect of flow channel parameters on the durability of PEMFC stack and analysis of hydrogen crossover mechanism

Polymer electrolyte membrane fuel cell (PEMFC) is a leading technology with a bright future in the field of transportation. The bipolar plate structure has a profound impact on the mass and heat transfer of PEMFC. In this study, the durability tests of two stacks with different channel depths are carried out for 1000 h respectively on the 1 kW fuel cell stack test platform. We detect the overall performance change of the stack and characterize the membrane electrode assembly at the end of the test. Based on the first principle calculation, the mechanism of membrane degradation and hydrogen crossover is analyzed, and some durability experimental results are explained. The results show that the durability of the PEMFC with a shallow flow channel is worse, the voltage drops significantly, and the hydrogen crossover increases significantly after 500 h. The first principle calculation results reveal that the chemical structure change of the membrane is caused by the free radical attack. Hydrogen crossover promotes center dot H to attack carbon-fluorine bonds. This paper reveals the mechanism of hydrogen crossover and its influence on the catalyst layer, which is helpful to improve the durability of PEMFC.