Durability Enhancement of Polymer Electrolyte Fuel Cells at Extreme Conditions: Cold Environmental Aspect

摘要

Polymer electrolyte fuel cells (PEFCs) can be widely used in the military as well as the public applications. However, still, there are critical obstacles for PEFC systems to be used in the real field. Among them, durability, performance and cost problems should be solved. In PEFC systems, water management is an important point to get enhanced durability as well as good performance. Especially the operation of fuel cell systems at sub-zero temperatures is one of critical issues in the military and vehicle applications. The recent results revealed that the weakened adhesive strength between the membrane and the electrodes is one of the main reasons of cell degradation at sub-zero temperature operating conditions. To mitigate the degradation, minimization of the absolute amount of water and good distribution of the remained water in the cell are necessary. Better interfacial contact, stiff gas diffusion layers (GDLs) and narrow channel width may be effective mitigation approaches. To confirm the above mentioned mitigation measurements, several kinds of GDLs, which have different properties, were investigated at the same freeze/thaw conditions. By changing the cell temperatures from -30 °C to 70 °C, the performance and the property changes of cells were observed with the number of temperature cycles. The post-analysis after the temperature cycles were conducted to check the changes in electro-chemical and physical properties. Finally the more preferable properties of GDLs on the PEFC durability could be suggested.