Micro PEM fuel cell current collector design and optimization with CFD 3D modeling

A computational fluid dynamics 3D modeling of a planar miniature proton exchange membrane fuel cell (PEMFC) is presented to optimize the current collector shape and dimensions in order to obtain the best electrochemical performances. Three geometries of current collector have been investigated and compared: serpentine, parallel and square openings. We showed that the current collector geometries giving the greatest performance (highest current and power density) appear to be the serpentine and parallel openings permitting a better distribution of the reactant to the catalyst layers. Influences of the ribs and openings current collectors dimensions of the serpentine design are analyzed. We found that the best electrochemical performances of the cell are reached for the tradeoff between ohmic loss and overvoltages. The important role of activation potential and ohmic potential to find this tradeoff is also introduced for the first time and demonstrated. Finally, we calculated that the power density supplied by the PEMFC stack can be increased by 55% by replacing the 1 μm thick continuous current collector (80 mW/cm2) by an optimized serpentine current collector design (124 mW/cm2), while keeping the same current collector thickness.