Synergistic Enhancement of Corrosion Resistance and Electrical Conductivity of TaTiN Coating for Ti Bipolar Plates

Abstract:

Coatings with strong corrosion resistance and high electrical conductivity on bipolar plates are urgently required for large-scale applications of proton exchange membrane water electrolysis (PEMWE). High-performance TaTiN coatings were fabricated via magnetron sputtering. Results show that TaTiN coatings with preferred (111) planes and refined grains show higher corrosion resistance and better electrical conductivity. On the one hand, the closely-packed (111) plane favors a dense texture; moreover, grain refinement can smooth the surface and facilitate the formation of a continuous, compact passive layer, thereby improving corrosion resistance. On the other hand, the small lattice mismatch between TaTiN (111) and Ti (0001) enhances interfacial bonding and thus electrical conductivity across the interface, resulting in lower interfacial contact resistance (ICR). The optimized TaTiN coating shows a low corrosion current density of 6.56×10^-7 A·cm^-2 and an ICR of 9.11 mΩ·cm², indicating the strong potential of TaTiN coatings to protect metallic bipolar plates in PEMWE systems.