Nb–Cr–C coated titanium as bipolar plates for proton exchange membrane fuel cells

Herein, a ternary Nb–Cr–C film is successfully prepared by arc ion plating for surface modification of titanium using as proton exchange membrane fuel cell (PEMFC) bipolar plates. Film morphology, composition as well as corrosion behavior, conductivity and performance of single cell are investigated. As results revealed, the Nb–Cr–C film is about 500 nm thick without obvious defects. Compared with the bare titanium, the corrosion current density of Nb–Cr–C coated titanium lowered to 0.022 μA/cm2 and -0.051 μA/cm2 in simulated PEMFC cathode and anode environments, respectively, accompanied with the interfacial contact resistance lowered to 1.15 mΩ cm2, indicating outstanding anti-corrosion and conductivity performance. The single cell with Nb–Cr–C coated titanium bipolar plates reaches its peak power density 1.167 W/cm2 at 2.2 A/cm2, which is comparable with that of graphite bipolar plates and apparently better than that of bare titanium bipolar plates. The remarkable improvements in both ex-situ tests and single cell tests suggest that the Nb–Cr–C coated titanium might be a proper material for PEMFC bipolar plates.