<italic>In Situ</italic> Quantification of Electronic Short Circuits in PEM Fuel Cell Stacks

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There is a need for increasing the durability of proton exchange membrane fuel cell systems. Membrane failure is usually generated by a chemical attack led by peroxide radical species. The chemical attack promotes pinhole formation that ultimately induces the shutdown of the fuel cell. An electronic short circuit between the anode and the cathode through the membrane has also been identified as a failure mode. However, the current resulting from H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> crossover is estimated to be an order of magnitude larger than the electronic current. As a consequence, the electronic short circuit is often disregarded. In the present work, we revealed numerous local hotspots in pristine membrane electrode assemblies (MEAs) that are sensitive to short circuits. Catalyst layer heterogeneities were found responsible for these hotspots. In use, these flaws do not directly impact the global performance but may induce premature degradation. With the use of an electrical passive technique, one can identify the electronic short-circuit resistance of membranes simply by charging and discharging the double-layer capacitor of the MEA. The integration of this technique into fuel cell systems was possible, and measurements were performed at different ageing times. They revealed a gradual increase in the number of cells with short circuit annunciating the failure of the entire stack.