Overcoming the Dilemma between Low Electrical Resistance and High Corrosion Resistance Using a Ta/(Ta,Ti)N/TiN/Ti Multilayer for Proton Exchange Membrane Fuel Cells

Bipolar plates in proton exchange membrane fuel cells (PEMFCs) are confronted by the dilemma of low contact resistance and high corrosion resistance; this study aimed to simultaneously satisfy these dimensions a harsh environment. Using thick multilayer coatings can improve resistance, but would be largely compromised. To address challenge, we propose compatible tantalum/titanium-based on 316L stainless steel (SS316L) as bipolar for PEMFCs. With transition layer, optimal TaN/(Ta,Ti)N/TiN/Ti coating exhibits an ultralow current density 0.369 μA·cm−2 (at +0.6 V vs. SCE) 6 mΩ cm2 at 138 N/cm2 after 5 h potentiostatic polarization, both which meet standard U.S. Department Energy. Electrochemical impedance spectroscopy (EIS) equivalent electrical circuit model further elucidated that significantly impedes oxidation reaction dissolution metals provides good protection SS316L.