Measurement of the local membrane resistance in polymer electrolyte fuel cells (PEFC) on the sub-mm scale

Based on a recently introduced principle for measuring current distribution in polymer electrolyte fuel cells on the sub-mm scale, a measurement method for determining the membrane resistance with sub-mm resolution, i.e. over the structure of flow field channels and ribs, has been developed and the results are presented for the first time. The principle is based on current pulses with simultaneous measurement of local current and voltage distribution before and after the rising current edge on the sub-mm scale, employing a recently introduced method for sensing the potential at the catalyst-gas diffusion layer interface. The method was applied to specialized cells operated at different gas humidities. The measurements show that the local membrane resistance varies most significantly under the channel of the flow field.