Enhanced electrical properties and fuel cell performance of 316L stainless steel bipolar plate coated with amorphous Ni-Mo-P layer

Amorphous Ni-Mo-P alloy coating was successfully electroplated on 316L stainless steel at two different electroplating current densities namely 30 and 100 mA cm·2 as metallic bipolar plate for using in proton exchange membrane fuel cells. Ex-situ and in-situ measurements of interfacial contact resistance between gas diffusion layer and bipolar plates were carried out in single cell hardware. Electrochemical impedance spectroscopy was also employed for in-situ performance diagnosis of bipolar plates during operation. The results showed that interfacial contact resistance of the bare 316L BPP was significantly decreased by deposition of conductive Ni-Mo-P coating. Moreover, increasing cell current density raised interfacial contact resistance, since that of the bare 316L bipolar plate was dramatically increased at high cell current densities. Moreover, the high frequency resistance of the cells was decreased with increasing cell temperature. After 115 h operation, the Ni- Mo-P coated 316L BPP deposited at current density of 100 mA cm·2 showed the most stability in interfacial contact resistance with minimum increase in high frequency resistance and also the lowest cell voltage loss among the cells, presenting the most promising behavior from the standpoint of fuel cell performance, interfacial contact resistance and electrochemical behavior which make it a promising candidate as metallic bipolar plate in PEMFC.