CrN Coating on 316L Stainless Steel via Inductively Coupled Plasma‐Enhanced Magnetron Sputtering as Bipolar Plates for Proton‐Exchange Membrane Fuel Cells

Abstract

Herein, CrN monolayer films are deposited on 316L stainless steel (316LSS) via inductively coupled plasma (ICP)‐enhanced magnetron sputtering technology to compensate the defects of bare 316LSS in an acidic, hot, and humid proton‐exchange membrane fuel cell (PEMFC) environment. To assess the anticorrosive performance and conductivity of CrN‐coated 316LSS, the electrochemical behavior and interfacial contact resistances (ICRs) of samples are measured before and after the modification. The results of the potentiodynamic polarization test show that CrN‐coated 316LSS possesses high anticorrosion performance according to the ultralow corrosion current density of 0.094 and 0.078 μA cm−2 under the imitated PEMFC anode and cathode environments, respectively. These values are far below the USA Department of Energy's requirements of <l μA cm−2. In addition, the ICR of CrN‐coated 316LSS also satisfies the DOE's target (<10 mΩ cm2), which is obtained to be 7.8 mΩ cm2 under 140 N cm−2. Through analysis of potentiostatic polarization and electrochemical impedance spectroscopy, it suggests that CrN‐coated 316LSS combines better long‐term stability under the working voltages of two electrodes in PEMFCs with better electrochemical impedance than bare 316LSS. Consequently, CrN coating on 316LSS via ICP‐enhanced magnetron sputtering technology can be potentially suitable for bipolar plate applications in PEMFCs.