Application of a segmented cell setup to detect pinhole and catalyst loading defects in proton exchange membrane fuel cells

Changes in the physical, compositional, and chemical properties of membrane electrode assemblies (MEAs) are usually considered as defects and have the potential to negatively affect fuel cell performance and durability and promote failures. Thus, studies of the defects' impacts and evaluations of the tolerance limits for properties of MEA components are important for the mass production of fuel cells: In the present paper, a segmented cell system was shown to be an appropriate method for the localization and identification of defects, such as pinholes and catalyst loading variations. The pinhole and anode loading defects were intentionally created at one of the inlet segments (segment 4), and the resulting impact was studied. The pinhole caused an increase in the H-2-crossover at the defected segment as well as downstream of the segment; it also caused a decrease in the open-circuit voltage (OCV). The pinhole was detected and localized by the application of spatial linear sweep voltammetry (LSV) for the H-2-crossover measurement and also by the application of open-circuit (OC) experiments. The decrease in the anode catalyst loading led to a local performance drop that was attributed to increased ohmic and mass transfer overpotentials. This defect caused an increase of high frequency resistance mainly due to a reduced thickness of the defected electrode area and the lack of an appropriate contact between the electrode and the gas diffusion layer. Consequently, spatial cyclic voltammetry (CV) has been shown to be capable of detecting loading defects in a segment's electrochemically active area. (C) 2012 Elsevier Ltd. All rights reserved.