Unveiling the dual role of penetration layers in proton exchange membrane fuel cells

초록

The penetration layer (PL) is an unintentionally formed structure resulting from the infiltration of microporous layer (MPL) slurry into the fiber-based substrate. It can significantly influence two-phase transport characteristics and the electrochemical performance of polymer electrolyte membrane (PEM) fuel cells. In this study, to theoretically elucidate the differences in multi-phase transport phenomena and water management effects depending on the presence of PL, simulations were conducted under fully humidified and non-humidified inlet conditions using a multi-scale, 3D two-phase PEM fuel cell model. Under fully humidified conditions, where flooding typically occurs, the PL was predicted to mitigate liquid water accumulation within the cathode gas diffusion layer (GDL) and restore oxygen diffusion pathways, thereby significantly reducing concentration overpotential. Under non-humidified (dehydration) conditions, the low gas permeability of the PL suppressed water evaporation, enhancing membrane hydration and ionic conductivity, which in turn reduced ohmic losses. Furthermore, the performance-enhancing effects of the PL were found to be highly sensitive to the channel/rib width ratio and dimensions of the cathode flow field. Configurations with wider channels and narrower ribs were shown to maximize the benefits of the PL. This study numerically demonstrates that the PL, often regarded as a by-product of MPL fabrication, can actively enhance water management within the cell. Its ability to maintain membrane hydration under dehydration conditions further improves heat dissipation and thermal stability. These findings provide new insights into integrated water and heat management strategies for practical PEM fuel-cell stack applications.

키워드