Long-term polarization accelerated degradation of nano-thin C/Ti coated SS316L bipolar plates used in polymer electrolyte membrane fuel cells

• Published in: International journal of hydrogen energy Vol. 47; no. 14; pp. 8974 - 8992
• Main Authors: Wang, Xian-Zong, Zhang, Meng-Meng, Shi, Dong-Dong, Zhang, Shang-Chen, Wu, Yuan-Min, Gong, Wei-Jia, Fan, Hong-Qiang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.02.2022
• Subjects: High transient potential; Interfacial contact resistance; Metal bipolar plates; Nano-thin C/ti coating; Polymer electrolyte membrane fuel cells; Potential fluctuation; Nano-thin C/ti coating; Interfacial contact resistance; Polymer electrolyte membrane fuel cells; High transient potential; Potential fluctuation; Metal bipolar plates
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.12.229

Dynamic potentials of polymer electrolyte membrane fuel cells (PEMFCs) lead to the corrosion of metal bipolar plates and significantly increase their interfacial contact resistance (ICR). Herein, two nano-thin C/Ti coatings with different thicknesses are prepared on SS316L (C/Ti/SS) and examined under three types of polarization potential modes. The C100Ti60 coating has improved corrosion resistance than C20Ti140 coating. The C100Ti60 coating exhibits a low ICR of 2.67 mΩ cm2 and a small corrosion rate of 1.47 μA/cm2, highlighting the high electrical conductivity and corrosion resistance. Moreover, C100Ti60/SS achieves a slight degradation of ICR after polarization at 0.67 V and cyclic polarization between 0.43 and 0.73 V. However, the high potential of 1.43 V induces severe delamination of C layer, resulting in a remarkable increase of ICR. Analysis suggests that the Ti layer improves the oxidation resistance and the C layer could provide effective protection when the potential is below 1.13 V. [Display omitted] •Two nano-thin C/Ti coatings with different thicknesses are prepared on SS316L.•Highly corrosion resistant and electrical conductive C100Ti60/SS is achieved.•Evolution of ICRs of C100Ti60/SS under three polarization modes are studied.•Anodic dissolution processes of C100Ti60/SS at different potentials are analyzed.•Correlation between ICR and negative current during cyclic polarization is discussed.