Ex-situ Accelerated Corrosion experiment and Various Electrochemical Characteristics of Carbon Coating by Doctor Blade Technology of Titanium Bipolar Plates for PEMFC

This investigation was devoted to exploring the electrochemical characteristics of titanium bipolar plates for PEMFCs. Grade 1 titanium specimens were coated with TiO ₂ , after which an additional layer of carbon was deposited onto the specimens using the roll-to-roll doctor blade method. X-ray diffraction analysis confirmed the presence of an anatase-structured TiO ₂ layer on the titanium after TiO ₂  + carbon coating, and an energy dispersive spectroscopic analysis of the cross-sections of the specimens confirmed the presence of a carbon coating layer. Ex-situ accelerated corrosion experiments performed in a simulated PEMFC environment demonstrated that the current density of the TiO ₂  + carbon-coated Ti was higher than that of the uncoated Ti during load fluctuation intervals. This high current density is attributed not to degradation due to oxidation reactions but to the electron charging and discharging associated with the formation of an electrical double layer. Electrochemical characteristic analysis revealed that even as an active peak was observed, the uncoated Ti exhibited a corrosion current density below 1 µA/cm ² , thus failing to satisfy the standards of the US Department of Energy (DOE). Conversely, the TiO ₂  + carbon-coated Ti met all relevant standards. Interface contact resistance measurements indicated that the pure titanium failed to meet DOE standards before and after all the electrochemical experiments. In contrast, the TiO ₂  + carbon-coated Ti complied with these standards before the electrochemical experiments as well as after the potentiostatic corrosion experiment and ex-situ accelerated corrosion experiment.