Mass transport phenomena in proton exchange membrane fuel cells using O2/He, O2/Ar, and O2/N2 mixtures. II: Theoretical analysis

The study presents an experimental investigation of proton exchange membrane fuel cells (PEMFCs) aimed at finding explanations for the enhanced slope of the linear region and the rapid fall-off of E with i at higher current density. An increase of thickness of the active layer is found to enhance the oxygen electrode performance because of the increase of the electrochemically active surface area. However, there is a limit to such an increase because mass-transport problems will be encountered at higher current densities. Operation of the PEMFC at a higher pressure has a significant effect of minimizing mass-transport limitations. An increase of the operating temperature at low pressure has a compensating effect on performance. (AIAA)