Study on Condition of Low-Cost Carbon-Based Surface Treatment for Application of Metallic Bipolar Plates in PEMFC

Metallic bipolar plates coated with low-cost carbon-based surface treatment were developed for polymer electrolyte membrane fuel cells(PEMFC) and were evaluated by properties(corrosion, contact resistance) and performance(I-V curve). The carbon-based coating by dry surface treatment exhibited a good mechanical strength and corrosion resistance. But these could not be applied as bipolar plates because of a high electrical resistance by non-conductive structure(sp3↑, sp2↓). In this study, we developed the metallic bipolar plates with conductive structure((sp3↓, sp2↑) by change of coating temperature and thickness.

The coating thickness(A type, B type) and temperature(A-1~4, B-1~4) were used as parameters for conductive bipolar plates. The B type sample was more thicker than A type and A-4 sample was treated with heat more higher than A-1. These samples were evaluated by properties and performance of unit cell.

The surface treatment temperature of A-3 sample exhibited low contact resistance and corrosion current density. This trend showed in B type sample. Therefore, the condition of A-3 or B-3 revealed the optimum temperature in this experiment. However, the increase of coating thickness was for nothing in properties. The fuel cell assembled from metallic bipolar plates coated with carbon-based surface treatment exhibited the same performance as compared with graphite.