The Potential Effect on the Performance of CrN/Cr-Coated SS316L Bipolar Plates and Their Durability in Simulated Cathodic HT-PEFC Environments

Abstract

This study further investigates the effect of potential on the corrosion resistance, the self-healing performance and the durability of CrN/Cr-coated SS316L bipolar plates with artificial defects (CR-316) in simulated cathodic HT-PEFC environments by means of electrochemical methods. The self-healing ability initiated by oxygen is relatively weak and needs the assistance of the cathode working potential for sealing. In some cases, the defects have spread over large parts of the bipolar plate. The influence of the potential on the corrosion resistance of the bare 316L and CR-316 specimens in the simulated cathodic HT-PEFC environments were investigated by electrochemical impedance spectroscopy. Moreover, the durability of the CR-316 specimens was examined under the various potential cycles in the simulated cathodic environment of HT-PEFC and O2 atmosphere. After 5000 CV cycles in the potential range of 0.4–1.0 V vs. RHE, the CR-316 specimens could maintain the integrity and good corrosion resistance against the hot phosphoric acid. The results demonstrate the superior performance of CR-316 and make it a prime candidate as a non-precious coating for metallic bipolar plates on the cathode side of HT-PEFCs.