Electrochemical Properties of NiO-YSZ Thin Films on 316 Stainless Steel Bipolar Plates Under a Simulated PEMFC Environment

Abstract

E-mail: hojang@korea.ac.krReceived November 16, 2011, Accepted December 30, 2011The corrosion resistance of 316L stainless steel coated w ith NiO-YSZ (Ni adde d yttria stabili zed zirconia) wasexamined in a proton exchange membrane fuel cell (PEMFC) environment. The NiO-YSZ coating was carriedout using a sol-gel dip coating method, and the corrosion resistance and interfacial contact resistance (ICR)were determined by the composition and morphology of the NiO-YSZ film. The corrosion resistance increasedwith increasing Ni content in the NiO-YSZ film, but rapid corrosion was observed when the YSZ filmcontained more than 15 wt % Ni due to surface cracks. The polarization resistance was improved by severalorders of magnitude when 316L stainless steel was coated with a 15 wt % NiO-YSZ film compared to bare316L. The ICR of the NiO-YSZ film was decreased to that of bare 316L when the YSZ film contained 25 wt %NiO, suggesting the possible application of NiO-YSZ coated stainless steel for a bipolar plate. Key Words : Ni, YSZ, Sol-gel, Metallic bipolar plate, PEMFCIntroductionThe bipolar plate used in proton exchange membrane fuelcells (PEMFCs) is a multifunctional component because itelectrically connects the cells in series, separates the gases inthe adjacent cells, and accommodates the gas flow channels.Therefore, bipolar plates need to be electrically conducting,mechanically strong, and resistant to corrosion.