Effect of pinhole location on degradation in polymer electrolyte fuel cells

• Degradation in a fuel cell with various pinholes was investigated.
• Mild defects may result in a temporarily improved performance.
• A correlation between carbon corrosion and hydrogen crossover was evident.
• Defects near the anode inlet have the strongest influence on degradation.
• Fuel starvation resulted in a more severe voltage drop with a perforated membrane.

This work analyses the impact of the location of pinholes in polymer electrolyte fuel cells on the degradation of the electrodes. Defects with a diameter of 0.45 mm were created in a 25 cm2 membrane electrode assembly (MEA) of a fuel cell. The MEA was operated and characterised using a segmented single cell. The effects of the pinholes on degradation were measured and evaluated. Defects affected the fuel cell behaviour during periods of hydrogen starvation, thus accelerating the degradation process of the carbon support as well as the loss of active platinum catalyst surface area. Furthermore, the effects of the induced pinholes on membrane degradation and performance decay were determined.Pinholes close to the anode inlet in general have shown a more severe effect on the fuel cell operation parameters, such as open circuit voltage, performance, membrane resistance and hydrogen crossover, than pinholes at any other locations. Also, electrode degradation was accelerated. These effects were mainly due to locally increased temperatures.