Performance Enhancement in Thin Film Solid Oxide Fuel Cells Using Metal-Mixed Ionic Electronic Conductors Bilayer Anode
Seungtak Noh, Gu Young Cho, Yoon Ho Lee, Wonjong Yu, Jihwan An, Suk Won Cha
A 70 nm-thick Ni layer deposited between the NiO-gadolinia doped ceria (NiO-GDC) anode and the anodic aluminum oxide (AAO) substrate successfully enhanced the electrochemical performance of thin film solid oxide fuel cells (TF-SOFCs) using the sputtering technique. The thickness ratio between the NiO-GDC and Ni layer on the cell performance was investigated. The TF-SOFCs with sputtered 210 nm-thick NiO-GDC and 70 nm thick Ni layers exhibited maximum power density of 170 mW/cm2 at 500 C, which was about two times higher than those without Ni layers (80 mW/cm2). The electrochemical impedance spectroscopy showed that the performance improvement mostly stems from two factors: the reduced ohmic and anodic activation resistances and the improved anodic kinetics. When the NiO-GDC layer is too thin (70 nm), the ionic conduction in the NiO-GDC layer became sluggish. Therefore, the maximum power density decreased to 132 mW/cm2. Thus, we can conclude a proper thickness ratio between the NiO-GDC and Ni layers is required to maximize cell performance.