Development and evaluation of nitride coated titanium bipolar plates for PEM fuel cells

Abstract In order to improve the conductivity of titanium bipolar plate under the premise of ensuring its corrosion resistance for the proton exchange membrane fuel cell (PEMFC), the nitride coatings are deposited on the surface of titanium bipolar plate via a powder immersion reaction assisted coating (PIRAC) method. Both the scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) show that the dense titanium nitride coatings with the thickness around 1.5–2.5 μm are successfully prepared. Furthermore, the X-ray photoelectron spectroscopy (XPS) results confirm the presence of TiN, TiNxOy and TiO2 phases on the surface of nitride coatings, and the content of these phases is tunable by adjusting the prepared temperatures. Both the microstructure, the thickness and the composition of the nitride coatings could be associated with the corrosion resistance and the interfacial contact resistance of the nitrided samples. We find that the nitrided samples prepared at 1000 °C could be the ideal mixed coating materials with the proper combination of the corrosion resistance and the interfacial contact resistance, which also show the best long-term stability in simulated PEMFC cathode environment.