Impedance Study of the Effect of Cell Compression on PEMFC Under Various Oxygen Supply Conditions

Abstract

Cell compression impacts the performance of polymer electrolyte membrane fuel cells (PEMFCs). A previous study has reported a trade-off between mass transport and contact resistances from cell compression [1]. Our study focuses on how the compression pressure affects polarization resistance under various oxygen partial pressure conditions. Without hot pressing the gas diffusion layers, a membrane electrode assembly with an electrode area of 1 cm2 was set in a housing in which the compression pressure could be adjusted [2]. Impedance spectra were measured at 0.7 A/cm2 under various oxygen partial pressure conditions. Figure 1 shows that polarization resistance decreases with increasing compression pressure under low compression pressure conditions, and conversely increases under high compression pressure conditions. The change in polarization resistance is more pronounced under low oxygen partial pressure conditions. In this contribution, the effect of cell compression on the different polarization processes will be discussed, considering the impact of compression pressure on catalyst layer thickness and porosity.