High corrosion resistance and through-plane electrical conductivity of C/Ti and C/Cr coated metal bipolar plates used in PEMFC

To improve the corrosion resistance and enhance the electrical conductivity in a simulated proton exchange membrane fuel cell, carbon bound SS316L stainless steel plates were modified with titanium (Ti) or chromium (Cr). The SS316L interfacial contact resistance of 312.38 mΩ·cm2 was reduced to 1.59 mΩ·cm2 when modified with Ti and to 1.32 mΩ·cm2 when modified with Cr. The increase in potential enhanced the shedding of C films and the oxidation and dissolution of Ti and Cr buffer layers. The corrosion current density in the C/Ti coating was lower than C/Cr coating under high voltage polarization. The oxidation of Ti and Cr buffer layers led to poor appetency between the C film and the SS316L and to degradation of the through-plane electrical conductivities in the C/Ti and C/Cr coated metal bipolar plates.