An Experimental Study of Wettability Control of Vanadium Oxide Thin Films on Stainless Steel Bipolar Plates for Enhanced Cold-start Capability and Water Repellency of Fuel Cells

Abstract

ABSTRACT

An Experimental Study of Wettability Control of Vanadium Oxide Thin Films on Stainless Steel Bipolar Plates for Enhanced Cold-start Capability and Water Repellency of Fuel Cells

Jun Seong PARK Dept. of mechanical engineering The Graduate School Hanyang University

Water management of polymer electrolyte fuel cell (PEFC) remains a major challenge for automotive applications because it has a deep affinity with performance of vehicles. For automotive applications, start-up of PEFC from sub-zero temperatures, known as cold-start is also an important research topic regarding performance and reliability of fuel cell vehicles. In this work we experimentally study the surface wettability of composite NTC thin films is of great importance to modify the surface characteristics between hydrophobicity and hydrophilicity of metallic substrates for advanced fuel cell applications, particularly for multi-functional metallic bipolar plates. Vanadium oxide films deposited on the flat surface of 316L stainless steel to investigate the hydrophobicity of the nanostructured thin films with organic solvent. Vanadium-based thin films on the surface of 316L stainless steel plates have been fabricated to enhance NTC property for cold-start solution and to modify the surface wettability by a dip-coating method via aqueous sol-gel process. Experimental analyses of thin films have been performed using diverse measuring equipment such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to investigate the chemical composition, crystallinity, and microstructure. In order to confirm the effects of organic templating agent adding on the surface wettability, we found that the composite thin films fabricated with hexadecylamine as an organic templating agent showed hydrophobic characteristics (CA>90°). As a result, the nanostructure of the thin films and organic solvent remain despite high annealing temperature (573.15 ~ 673.15 K). Experimental result could provide applications for various fields such as fuel cell bipolar plates with cold-start capability and great water repellency by coating them to nanostructured hydrophobic vanadium oxide films.