A novel three-dimensional flow field design and experimental research for proton exchange membrane fuel cells

As an indispensable part of proton exchange membrane fuel cells (PEMFCs), flow field plays a vital role in cell performance especially at high current density. Plenty of works have been done on flow fields, and baffled flow fields become research hotspots in recent years. However, owing to the processing difficulty of these types of flow fields, the vast majority of previous works just stay in the simulation level and very little experimental data can be found. In this work, a series of three-dimensional flow fields (3DFFs) with trapezoid-shaped baffles are designed and machined. Polarization curves of the designed flow fields under various operation conditions are experimentally recorded and it's no doubt that the designed flow fields can improve cell performance obviously owing to their enhanced oxygen transport and water management. The relation between transport ability and inclination angle was studied detailedly through electrochemical impedance spectroscopy (EIS), limiting current density, polarization curves and pressure drops. The results indicates that the flow field with small inclination angle is more suitable for the scenarios with high water content, such as high relative humidity, low stoichiometric ratio, high operating pressure, and etc. On the contrary, the flow field with big inclination angle is more appropriate for low water content cases. What's more, pressure drops from cathode inlet to outlet of different flow fields are tested and the results show that the designed flow fields increase little parasitic power compared with the conventional parallel flow field (CPFF), which further proves that the designed flow fields are fit for PEMFCs.