Tailoring 3D structured nanofibrous nickel/gadolinium-doped ceria anodes for high-performance thin-film solid oxide fuel cells

Solid Oxide Fuel cells (SOFCs) operating at low temperature (450–600 °C) have been investigated in order to achieve rapid on/off, improved long-term stability and a wide selection of low cost materials, but decrease in ionic conductivity and slowed electrode kinetics still remain as challenges. Anodized aluminum oxide (AAO)-supported thin-film SOFCs (TF-SOFCs) fabricated by thin film deposition techniques exhibit exceptional performances at low temperature owing to extremely reduced electrolyte thickness and nanostructured electrodes. However, limited electrical conduction in anodes on AAO coerces metallic anodes and studies on cermet anodes are still insufficient. In this work, nickel-gadolinium doped ceria (Ni-GDC) thin-film anodes with different thickness are co-sputtered on AAOs with subsequently sputter-deposited yttria-stabilized zirconia electrolyte and platinum cathode. The TF-SOFCs represent maximum power densities of 223, 281, 353 and 177 mW/cm2 at 500 °C for Ni-GDC thickness of 300, 500, 800, 1000 nm, respectively. 800 nm thickness shows the best performance since porosity is maximized by columnar growth behavior during sputtering and lateral electrical conduction is consistently improved as the anode becomes thicker, which is confirmed by electrochemical impedance spectroscopy, field-emission scanning electron microscopy, and focused ion beam. Transmission electron microscopy/energy-dispersive X-ray spectroscopy are utilized to get structural and chemical information.