Effects of Microstructure of Ni Anode on Nanotemplate Based Low Temperature Solid Oxide Fuel Cells

For nano-porous anodized aluminum oxide (AAO) template based low temperature solid oxide fuel cells (LT-SOFCs), anode structure has crucial effects on electrochemical characteristics because of triple phase boundary densities and electrical connectivity of metal catalysts on porous AAO substrates. In this study, we investigated effects of fabrication processes of Ni anode for AAO template based LT-SOFCs. Ni anodes were prepared at various deposition pressure, i.e. low pressure, high pressure and low pressure–high pressure, on nano-porous AAO substrates by physical vapor deposition. Surface morphology and cross-sectional structure of various Ni anodes were systematically evaluated. Electrochemical characterizations of LT-SOFCs with various anode structures were successfully conducted at 500 °C. The Ni anode prepared at low pressure showed high electrical conductivity and low catalytic activity. However, Ni anode which was fabricated at high pressure exhibited poor electrical conductivity and good catalytic activity. Bilayer Ni anode which was deposited in sequence at low pressure and high pressure presented both good electrical conductivity and good catalytic activity. The LT-SOFC with the bilayer Ni anode cell achieved the best performance, 201 mW/cm2 at 500 °C. Electrochemical impedance spectroscopy analysis was conducted to reveal detailed behaviors of AAO based LT-SOFCs. Therefore, we successfully optimized the anode structure for high performance AAO template based LT-SOFCs.