Corrosion behavior of Ta and TiN double-layer-coated SUS316L for PEMFC bipolar plates using plasma-enhanced atomic layer deposition and magnetron sputtering

In this study, the corrosion behavior of Ta and TiN double-layered-coated SUS316L is investigated for protonexchange membrane fuel cells (PEMFCs) bipolar plates. The surface of SUS316L is modified by depositing 4.5 mu m of Ta and 200 or 400 nm of TiN using magnetron sputtering and plasma-enhanced atomic layer deposition, respectively. The experimental results reveal that this coating significantly enhances the corrosion resistance and reduces the interfacial contact resistance of the bipolar plate. Under electrochemical conditions that are 500 times more acidic than those specified by the Department of Energy (DOE), the coated SUS316L achieves a corrosion current density of only 1.0 mu A/cm2 at 0.6 VSCE. The corrosion current density reduces up to more than two orders of magnitude, and the interfacial contact resistance with carbon paper is below 10 m omega cm2 at compression forces below 140 N/cm2, thus meeting the DOE 2025 target value for both corrosion current density and interfacial contact resistance. Our findings suggest the potential of Ta and TiN double-layered-coated SUS316L as durable bipolar plate materials for PEMFCs.