A comparative study of corrosion resistance evaluation of bipolar plate materials for proton exchange membrane fuel cell

Reliable assessment of corrosion resistance is critical in seeking the appropriate materials for bipolar plate (BPP) while corrosion of BPP still remains a key challenge in proton exchange membrane fuel cell (PEMFC). In this work, the effects of accelerated and simulated testing conditions as well as potential on corrosion behaviours and microstructure evolutions of stainless steel bipolar plate are studied with SS316L by potentiodynamic and potentiostatic tests, and electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). Moreover, the rationalities of evaluating corrosion resistance of materials for BPP under accelerated and simulated testing conditions with different potentials are analyzed based on electrochemical tests and corrosion mechanisms of SS316L. The results reveal that pitting is the main corrosion mechanism for SS316L in the simulated or real PEMFC working conditions. However, the dominant corrosion mechanisms are changed to intergranular and uniform corrosion at the potentials of 1.15 V–1.55 V (vs. SHE), respectively, when tests are performed in accelerated conditions with pH = 0.3. The results indicate that the accelerated conditions may be inappropriate for evaluating corrosion resistance of materials for BPP, especially at higher potentials.