Low Interfacial Contact Resistance between Carbon-Based Gas Diffusion Layer and Sputter-Deposited Anatase TiO2
Tomohito Sudare, Reiichi Ueda, Yumie Miura, Ayaka Nakamura, Han Xu, Ryo Nakayama, Kazunori Nishio, Ryota Shimizu, Naoomi Yamada, Taro HitosugiAbstract
Reducing the interfacial contact resistance between separators and gas diffusion layers is critical for achieving high-power polymer-electrolyte membrane fuel cells. Stringent targets for contact resistance below 3.0 mΩ cm2 have been proposed; however, achieving such values using practical separator materials remains challenging. Here, we demonstrate that electrically conductive anatase Nb-doped TiO2 (TNO) thin films deposited onto stainless steel separators by RF magnetron sputtering exhibit a low contact resistance of 2.6 mΩ cm2 against carbon-based gas diffusion layers. Postdeposition vacuum annealing at 500 °C, suitable for practical stainless steel, reduces contact resistance. X-ray diffraction, electron backscattering diffraction, and Raman spectroscopy mapping reveal that a high carrier density (∼1021 cm–3) in Nb-doped TiO2 thin films plays a key role in reducing interfacial contact resistance. These findings highlight TNO as a promising inorganic coating material for next-generation high-power fuel cells.