Abstract
This work explores how the performance of a high-temperature polymer electrolyte membrane fuel cell is affected by the degree of compression. Contact pressure measurements in the range of 2 to 25 bars have been conducted on commercial membrane-electrode-assemblies (MEAs). When increasing the contact pressure, the MEA performance continuously decreases for lower current densities and increases or goes through a small maximum for higher current densities. The electrochemical characterization reveals a decrease in membrane as well as contact resistance and shows an increase in mass transport restriction, hydrogen crossover as well as electrical short circuits. The electrochemical active surface area is not affected by contact pressure rising. A comparison of two flow field types illustrates that the MEA performance not only depends on the geometry of the analyzed flow fields, but it is also influenced by the real contact area between flow field and MEA surface.