Local measurements of hydrogen crossover rate in polymer electrolyte membrane fuel cells

Hydrogen crossover is the main reason for membrane degradation in polymer electrolyte membrane fuel cells (PEMFCs). In this study, local measurements of the hydrogen crossover rate at the cathode in a PEMFC are investigated to analyze the distribution of hydrogen crossover rates under various temperature and relative humidity (RH) conditions. The bipolar plate for the cathode side is specially designed for local measurements. Results show that hydrogen crossover appears to occur mostly near the gas inlet region, and reduced crossover amounts near the outlet region. The hydrogen crossover rates increase with decreasing the nitrogen flow rates at a given section. The effects of temperature and RH on the hydrogen crossover rate over the entire area of the fuel cell are also analyzed and compared with the results of the open circuit voltage (OCV). The results show that the hydrogen crossover rate increases with the increase in both cell temperature and RH, resulting in a decrease in the OCV.