Performance of Tantalum Modified 316L Stainless Steel Bipolar Plate for Proton Exchange Membrane Fuel Cell

The drawback of corrosion resistance and surface conductivity are two obvious defects to limit the large-scale application of 316L stainless steel (316L SS) as bipolar plate (BP) in proton exchange membrane fuel cell (PEMFC). A tantalum (Ta) modified coating was prepared by plasma surface modification technology on the surface of 316L SS bipolar plate to improve the functional performance. The electrochemical behavior of untreated 316L SS and Ta modified bipolar plate was investigated in simulated PEMFC operating environment. The results of potentiodynamic polarization, potentiostatic polarization and electrochemical impedance spectroscopy (EIS) reveal that the Ta coating considerably improves the corrosion resistance of 316L SS bipolar plate. The potentiodynamic polarization result shows that a more positive self-corrosion potential is obtained by Ta modified bipolar plate, and the corrosion current density is obviously reduced to 1.95 mu A cm(-2) and 0.14 mu A cm(-2) in simulated cathodic and anodic environment, respectively. The Ta modified bipolar plate exhibits a satisfactory interfacial contact resistance (ICR), and still remains lower ICR than bare substrate after potentiostatic polarization test for 4 h. In addition, the high water contact angle (94.5 degrees) for Ta coated bipolar plate implies more superior hydrophobic performance, which is convenient for water management within the PEMFC.