Self-assembled graphene film to enable highly conductive and corrosion resistant aluminum bipolar plates in fuel cells

Abstract

We report in this paper a novel method to form protective graphene film on aluminum substrate, which is particularly applicable to bipolar plates in proton exchange membrane (PEM) fuel cells. By simply immersing an aluminum sheet in an aqueous solution of graphene oxide (GO), a layer of cross-linked GO gel forms on the aluminum sheet, taking advantage of dissociated aluminum ions as a cross-linker. Then the cross-linked GO is converted to graphene at 400 °C in hydrogen atmosphere. The chemistry of the self-assembled GO layer and its conversion to graphene film is revealed by FTIR and XPS. Under simulated fuel cell environment the graphene coated aluminum sheet shows a corrosion current density of <1 × 10−6 A/cm2, which is around four orders of magnitude lower than a bare aluminum sheet. Meanwhile, the graphene film on aluminum results in a much lower and more stable interfacial contact resistance (ICR) of <5 mΩ cm2. These enable the graphene coated aluminum sheet to meet the U.S. DOE targets of 2020 for bipolar plates in terms of both the corrosion and electrical resistance. Thus the proposed method is very promising for protecting aluminum bipolar plates in PEM fuel cells.