Design of the Catalyst Layers in PEMFCs Using an Adjoint Sensitivity Analysis Approach

A numerical algorithm is presented for the large-scale optimization of catalyst distribution in proton exchange membrane fuel cells (PEMFCs). The algorithm is based on the evaluation of catalyst sensitivity functions, which show how much the cell voltage or discharge current are increasing when a small amount of catalyst is added at given locations inside the catalyst layers. The catalyst sensitivity functions are evaluated with relatively low computational cost using an adjoint space approach. Using the proposed algorithm one can compute the exact, optimum, three-dimensional (3-D) distribution of platinum particles inside the catalyst layers in order to maximize the overall power density of the cell. It is shown that the optimum distribution depends on the discharge conditions, on the positions of landings and openings, and on the geometry and dimensions of the layers. In general, the optimum catalyst density in the cathode catalyst layer should be larger at the membrane than at the gas diffusion layer interface. In addition, the catalyst density should be slightly larger under the gas channel and smaller under landings.