MODELLING ANALYSIS OF DEGRADATION IN LOW PLATINUM POLYMER ELECTROLYTE MEMBRANE FUEL CELLS

Durability is a key issue of polymer electrolyte membrane fuel cells (PEMFC) with low Platinum loading, mainly because of the instability of Platinum catalyst nanoparticles in the cathode catalyst layer (CL). Degradation of catalyst is critical in consequence of several mechanisms, among which Platinum dissolution. As proposed in the literature, a possible strategy to mitigate Platinum dissolution consists in the development of CLs with gradient properties. In the present work, a theoretical analysis of Platinum dissolution is applied to the interpretation of degradation data recorded under accelerated stress tests (AST) on catalyst-coated membranes (CCMs) with 25 cm2 active area and low Pt loading. A transient model referenced to the literature has been calibrated and validated on a set of experimental data to get insight into the catalyst degradation. The model predicts the formation of a catalyst depleted zone near the interface with polymer membrane, in agreement with TEM observations and the effect of a gradient catalyst structure in the catalyst layer is analyzed.