Understanding Differences in the Performance of Laboratory Scale PEMFCs: I. The Effect of Active-Area

The ability to compare, analyze, and interpret laboratory-scale experimental data for polymer electrolyte membrane fuel cells (PEMFCs) is often limited by differences in the performance between 25 cm2 and 50 cm2 active area cells. The present study includes the material of gas diffusion layers (GDL), their compression pressure, and the operating conditions to quantify and understand the effect of these factors on the performance of PEMFCs with different active area of electrodes. The experimental data show that under the same compression the internal compression pressure is higher for smaller cells compared to larger cells. Typically one assumes by increasing the compression pressure that the contact resistance is decreased and better performance is obtained. However, further increase of compression may cause mass transfer resistance inside of GDL due to the change of physical properties including pore size distribution.