A Segmented Microstructured Flow Field Approach for Submillimeter Resolved Local Current Measurement in Channel and Land Areas of a PEFC

A method for the direct measurement of the local cell current with submillimeter resolution in polymer electrolyte fuel cells (PEFCs) is presented. The approach employs a segmented microstructured flow field at the anode, which is operated in differential cross-flow mode. Therefore, the anode acts as a quasi-homogeneous counter electrode. Due to the segmentation, the direct measurement of the local cell current with a high spatial resolution of 400 mu m in channel and land areas of the cathode flow field becomes possible. The potential of the method is demonstrated here in submillimeter-resolved local current density and local cyclic voltammetry measurements. The results clearly show that effects, which occur due to inhomogeneous operation of PEFCs in the down-the-channel direction on the length scale of tenths of centimeters, have their counterparts in the perpendicular-to-the-flow-channel direction on the millimeter scale of channel and lands and, hence, must be considered with equal attention.