The objective of this post-doctoral position is to understand how a realistic manufacturing defect in the Membrane Electrode Assembly (MEA) can affect the performance loss and the degradation rate of PEMFC stacks. Among the most common defects, the lack/absence of active layer (particularly at the anode side where loadings are very low), the presence of agglomerates, cracks or excessive thickness in the active layers or in the microporous level of the GDL are often encountered locally (few cm²). Here, this work will rely on the expertise at CEA LITEN to produce MEA with a controlled structure (homogeneous deposits, good membrane|electrode interface, mapping of local catalyst loading). Both homogeneous and defective MEA with controlled properties, will be tested electrochemically.
The tests will notably include clever coupling between the different physical and electrochemical characterization methods possible ex-situ, operando or post-mortem. Among them, magneto-tomography, a technique based on measuring the magnetic field generated by the current passing through the stack, will continue to be developed. These measurements will make it possible to quantify the 3D effect of defects during operation. Finally, the post-doctoral fellow will use existing modeling tools to improve the prediction of the lifespan of PEMFCs related to the initial local properties of MEA.
All these experimental and simulation works will make it possible to correlate local operational heterogeneities and the degradation mechanisms associated with the defects depending on their nature or their positioning in the cell. Consequently, this study will provide some key-recommendations for the type and size of defects acceptable within MEA in relation with the operating and lifespan specifications of the PEMFC system.