Polyacrylonitrile Infused in a Modified Honeycomb Aluminum Alloy Bipolar Plate and Its Acid Corrosion Resistance

Bipolar plates, accounting for a large proportion of proton exchange membrane fuel cells (PEMFCs), are highly susceptible to corrosion by H+, SO4 2–, and so on because of the strong acid-rich and oxygen/hydrogen-rich environments. In this work, the corrosion resistance of aluminum alloy bipolar plates modified in the cathodic environment of PEMFCs has been investigated. A honeycomb structure is constructed by anodizing on an aluminum alloy (AA5052) bipolar plate, and a polyacrylonitrile (PAN) film is prepared by infusing PAN solution on the surface. From scanning electron microscopy and atomic force microscopy, we observe that the porous structure of the aluminum alloy surface is more advantageous for enhancing the mechanical engagement between PAN and the aluminum alloy. Therefore, the PAN film is dense and smooth. Electrochemical tests confirm that the PAN film greatly improves the corrosion resistance of the aluminum alloy bipolar plate under the cathodic environment of the PEMFC. When graphene oxide (GO) is added, the charge-transfer resistance (R ct) is not only improved but also the stability under oxygen-rich acidic conditions is prolonged.