The polymer electrolyte membrane fuel cell(PEMFC) is being considered as a clean source of power for the application of future energy owing to its high-power density, lower operating temperature than other fuel cells, and environment-friendliness [1]. For commercialization, the cost of bipolar plates (BPs) is a crucial factor among cell components, which comprises a high percentage of the total volume, weight, and the cost [2]. Graphite BPs is widely used due to high chemical stability and low surface contact resistance, but brittleness and machining cost are the critical concerns [3]. Stainless steel is commonly utilized an alternative material due to their high strength and chemical stability, low gas permeability. However, stainless steel suffers corrosion during PEMFC operation. Such corrosion deteriorates cell performance by dissolution of the metal ion into gas diffusion layer and increased interfacial contact resistance(ICR) of the formation of the passivation film [4]. Titanium nitride(TiN) can be one of the promising protective coating material in PEMFC due to the excellent durability, chemical stability, as well as good electrical conductivity. Various methods such as CVD [5], PVD [6], and sputtering [7] have been investigated to fabricate TiN films.

In this study, we explore electrophoretic deposition (EPD) of TiN layers. It is known that EPD provides simple, versatile, easy adjustment of coating thickness and cost-effective method to fabricate homogeneous coatings onto complex shape as well as a porous substrate [8].  TiN powders were coated successfully onto a 316 stainless steel by EPD. The different particle size of TiN including 20nm, 80nm and 800nm TiN powders was used to investigate morphology of coating layers, EPD kinetics and mechanism. In addition, two kinds of additives, PDADMAC and PEI were used to obtain a uniform suspension and EPD mechanism. Although both additives cationic polymers, different polymeric structure and molecular weight would influence condition of suspensions and potentially properties of coating layers. The morphologies and structure of TiN coated surface were analyzed by SEM and XRD. The potentiodynamic and potentiostatic electrochemical tests were conducted to measure the corrosion resistance for the applicability of EPD of TiN as a protective layer of bipolar plate in PEMFC.

References

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[2] Wang, Heli, Mary Ann Sweikart, and John A. Turner. "Stainless steel as bipolar plate material for polymer electrolyte membrane fuel cells." Journal of Power Sources 115.2 (2003): 243-251.

[3] Beaudin, Marc, et al. "Energy storage for mitigating the variability of renewable electricity sources: An updated review." Energy for Sustainable Development 14.4 (2010): 302-314.

[4] Makkus, Robert C., et al. "Use of stainless steel for cost competitive bipolar plates in the SPFC." Journal of power sources 86.1 (2000): 274-282.

[5] Mahieu, Stijn, Diederik Depla, and Roger De Gryse. "Characterization of the hardness and the substrate fluxes during reactive magnetron sputtering of TiN." Surface and Coatings Technology 202.11 (2008): 2314-2318.

[6] Altun, Hikmet, and Hakan Sinici. "Corrosion behaviour of magnesium alloys coated with TiN by cathodic arc deposition in NaCl and Na 2 SO 4 solutions." Materials Characterization 59.3 (2008): 266-270.

[7] Zhang, Dongming, et al. "Corrosion behavior of TiN-coated stainless steel as bipolar plate for proton exchange membrane fuel cell." International Journal of Hydrogen Energy 35.8 (2010): 3721-3726.

[8] Kanamura, Kiyoshi, and Jun-ichi Hamagami. "Innovation of novel functional material processing technique by using electrophoretic deposition process." Solid State Ionics 172.1 (2004): 303-308.

 

Acknowledgement

This work was partially supported by Agency for Defense Development (ADD) as global cooperative research for high performance and light weight bio-urine based fuel cell (UD160050BD), the Ocean University of China-Auburn University (OUC-AU) Grants program, and the International Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (20158520000210).