Temperature-relevant degradation in amorphous carbon coated SS316L bipolar plates for PEMFC.

The corrosion of metallic Bipolar Plates (BPs) has become a key bottleneck in the practical application of proton exchange membrane fuel cells (PEMFCs). Environmental factors inside the PEMFCs significantly accelerate the degradation of electrical conductivity and durability of metallic BPs. In this work, we investigated the corrosion behavior and conductive properties of amorphous carbon coating (a-C) coated SS316L in a simulated PEMFC environment at various operating temperatures. The results showed that the corrosion current density (I corr) of a-C varied in a range of 2.3–8.7 nA/cm2 when subjected to a temperature range of 40–80 °C. Additionally, the interfacial contact resistance increased from 4.36 to 9.56 mΩ/cm2 with a rise in temperature. The reasons could be ascribed to two aspects. First, the a-C maintained the good chemical stability of sp2/sp3 bonds regardless of temperature changes, favoring remarkable anti-corrosion and good conductivity. Second, the higher temperatures intensified the penetration of corrosive species, accelerating the dissolution process of a-C coated SS316L and leading to substantial corrosion failure. [Display omitted] • a-C coatings were fabricated on SS316L by a hybrid magnetron sputtering technique. • a-C coated SS316L enhanced corrosion resistance and interfacial conductive resistance in a simulated PEMFCs condition. • Increasing operating temperature slightly sacrificed the protective capability of a-C due to dissolution of metallic ions. • Strongly chemical stability of a-C favored long-term durability at high running temperature. [ABSTRACT FROM AUTHOR]