Development of Multiple Electrospray Nozzles for Fabricating Catalyst Layers of Polymer Electrolyte Fuel Cells

The electrospray (ES) method can be used to make porous, high-performance and low-Pt-loading catalyst layers (CLs). In our group's previous work, we succeeded in improving the cell performance in low-Pt-loading polymer electrolyte fuel cell cathode CLs by the use of a single-pin-nozzle ES method. However, the coating amount of the ES method is too low to be applied in mass production. In the present work, we have developed multi-pin nozzles. We started with the examination of two single-pin nozzles and confirmed that the ES method with plural nozzle pins was possible. We created a seven-pin nozzle as the first multi-pin nozzle. The uniformity of both the amount and scattering direction of the ink emission from that nozzle was deficient. We found that electrostatic-field control pins and plate were effective in correcting the behavior. Next, we created a 12-pin nozzle that was also equipped with electrostatic-field control pins and plate. We examined the length of the electrostatic-field control pins and the pin pitch with that nozzle. Finally, we increased the number of the nozzle pins to 72. The cathode CLs coated with that nozzle exhibited higher uniformity and cell performance in comparison with CLs coated by use of the pulse-swirl-spray method.