Recent progress of catalyst ink for roll-to-roll manufacturing paired with slot die coating for proton exchange membrane fuel cells

Roll-to-roll (R2R) manufacturing paired with slot die coating is a promising route to realize the mass production of catalyst layers of proton exchange membrane fuel cells and achieve a sharp decrease in manufacturing costs through scale effect. Catalyst ink runs through the route and governs the ultimate structure of catalyst layer. Therefore, designing and preparing an optimal high-solid content catalyst ink and figuring out how to utilize it well in the R2R process has become a significant challenge. Herein, recent progress in catalyst ink is focused on design, preparation, rheology, slot die coating, and drying process. This review is a significant step forward in providing fundamental knowledge and understanding of the nature of advanced catalyst ink and its compatibility with the R2R process which are essential for designing and manufacturing excellent catalyst layers.