The bipolar plate (BP) serves as one of the crucial components in proton exchange membrane fuel cells (PEMFCs). Among BP materials, metallic BPs are widely employed due to their outstanding comprehensive properties. However, the interfacial contact resistance (ICR) between BP and gas diffusion layer together with corrosion of metallic BP under acidic operating conditions degrades the performance and stability of PEMFCs. Herein, an approach is proposed for the surface reinforcement of titanium (Ti) alloy BPs, relying on a directly grown vertical graphene (VG) coating via the plasma-enhanced chemical vapor deposition method. Compared with bare Ti alloy, the corrosion rate of VG-coated Ti alloy reduces by 1-2 orders of magnitude in the simulated PEMFC operating environments and ICR decreases by ≈100 times, while its thermal conductivity improves by ≈20% and water contact angle increases by 68.1°. The results can be interpreted that the unique structure of VG enables excellent electrical and thermal conduction in PEMFCs, and the highly hydrophobic VG coating suppresses the penetration of corrosive liquid as well as contributing to water management. This study opens a new opportunity to reinforce metallic surfaces by the robust and versatile VG coating for high-performance electrodes used in energy and catalyst applications.
Keywords: corrosion resistance; hydrophobicity; interfacial contact resistance; plasma-enhanced chemical vapor deposition; titanium alloy bipolar plates; vertical graphene.
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