Electrochemical behavior of surface treated metal bipolar plates used in passive direct methanol fuel cell

Corrosion resistance performance of SS316L treated by passivation solution was investigated in a simulated environment of the passive direct methanol fuel cell (DMFC). Electrochemical impedance spectroscopic (EIS) test showed that polarization resistance of untreated and treated SS316L were 1191 Ω cm2 and 9335 Ω cm2, respectively. The above result agreed with the Tafel slope analysis of potentiodynamic polarization curves. Comparing the untreated and treated SS316L in the simulated environment of DMFC anode working conditions, it was observed that the corrosion current density of treated SS316L as estimated by 4000 s potentiostatic test reduced from 38.7 μA cm−2 to 0.297 μA cm−2, meanwhile, the current densities of untreated and treated SS316L in cathode working conditions were 3.87 μA cm−2 and 0.223 μA cm−2, respectively. It indicated that the treated SS316L should be suitable in both anode and cathode environment of passive DMFCs. The treated SS316L bipolar plates have been assembled in a passive single fuel cell. A peak power density of 1.18 mW cm−2 was achieved with 1 M methanol at ambient temperature.