The effect of pin-type flow field plate design on the current distribution in a H2-fed polymer electrolyte fuel cell

Abstract

The flow field plate (FFP) design is a key factor for enhancing the electrochemical performance of Polymer Electrolyte Fuel Cells (PEFCs) through optimal reactants’ distribution, low-pressure drops, and efficient water removal. The effect of geometrical features of the pin-type FFP design on the electrochemical performance of a 48 cm2 H2-fed Fuel Cell (FC) was assessed through polarization curves recording and current and temperature distribution maps along the electrode active area. The study was performed by changing excess air stoichiometry and cathode relative humidity (RH). Low-pressure drops were measured using pin-type FFPs; regardless of geometrical features, they were one order of magnitude lower than those of a single-channel serpentine FFP. Channel width and number of pins greatly influenced the current distribution along the active area and, consequently, the electrochemical performance of FCs. In particular, the best electrochemical performance was reached at air stoichiometry 4 and cathode RH = 100 % by using FFP with the highest coverage factor (65 %) and the lowest channel width (1 mm). Current distribution maps demonstrated that this FFP geometry led to an almost homogeneous current distribution and efficient water removal also at high current density values. On the contrary, low coverage factor (45 %) and high channel width led to worse electrochemical performances due to an uneven reactants distribution and an inefficient water removal, causing cell flooding.