Smart catalyst deposition by 3D printing for low temperature fuel cells

Polymer Electrolyte Membrane Fuel Cells (PEMFC) are arguably the most robust and integrated into various industry sectors among fuel cells, as they operate at low temperature and exhibit short start-up time. Currently, PEMFC manufacturing is transitioning from low-volume to mass production. However, the major hindrance against their massive use consists of high materials costs, low power density and relatively short lifetime. Notably, the need for employing platinum as a catalyst promotes exploring more convenient and effective manufacturing routes. The present work focuses on applying a microextrusion-based 3D printing system to deposit catalyst layers onto the Membrane-Electrode Assembly (MEA). A commercial 3D printer was modified to support the MEA substrate; furthermore, a peristaltic pump was inserted to supply the microextrusion printhead with the catalyst-endowed ink, finally released by a syringe. The main objectives of this work were to provide optimized compositions of catalyst inks suitable for MEA and (Gas Diffusion Layer) GDL preparation, and to assess the effectiveness of the microextrusion-based 3D printing technique in yielding homogeneous coatings. The ink was a mixture of distilled water, ethanol and graphite. Granulometric and rheometric analyses were carried out to characterize inks in a quest for low viscosity and short drying time. Repeatability of released flow rate and ink homogeneity onto the GDL target surface were also evaluated by statistical analysis. The final assessment of the coated substrates was performed by measuring the characteristic polarization curve. The results suggest that microextrusion-based 3D printing can be considered as a promising technology for fuel-cell manufacturing.