Performance improvement by a glue-functioned Nafion layer coating on gas diffusion electrodes in PEM fuel cells

• Extra liquid Nafion layer was coated on the surface of gas diffusion electrode (GDE).
• 0, 0.1, 0.3, and 0.5 mg cm−2 glue-functioned Nafion layers were coated for comparison.
• The GDE coated 0.3 mg cm−2 Nafion layer shows the best performance.
• The performance of the GDE coated 0.3 mg cm−2 Nafion is 55% better than that of without the Nafion layer.

To reduce the performance difference of membrane electrode assembles (MEAs) between catalyst coated membrane (CCM) and gas diffusion electrode (GDE) methods, this study presents a novel structure of a glue-functioned Nafion layer coating on the catalyst layer of GDEs to enhance performance. The process of hot pressing is omitted from the membrane electrode assembly (MEA) fabrication in this study. In exploring the effect of the glue-functioned Nafion layer, five MEAs are compared, including one made by the CCM method and four by the GDE method. Loadings of 0, 0.1, 0.3 and 0.5 mg cm−2 of glue-functioned Nafion layer are coated on the surface of the catalyst layer at room temperature with a condensed Nafion solution (20 wt%). The performance of the 0.3 mg cm−2 Nafion layer coating improves 55% compared with that without an extra Nafion layer for the peak power density, and the performance difference reduces from 61.2% to 39.4% when compared with the one using the CCM method. However, the performance of the 0.5 mg cm−2 Nafion layer coating is almost the same as without the Nafion layer. This indicates that increased Nafion cannot guarantee higher performance.