Performance and Stability Enhancement of Ni-Based Cermet Anode Using Atomic Layer Deposited Ruthenium for Direct Methane-Fueled Low-Temperature Solid Oxide Fuel Cell

Abstract

Nickel (Ni) based cermet, e.g., Ni-doped zirconia(e.g., YSZ) and Ni-doped ceria(e.g., GDC), is the most widely used anode material for solid oxide fuel cell (SOFC). SOFC has been considered as a promising energy converter because of its high efficiency, eco-friendliness, and fuel flexibility. However, recently, SOFC operating below 500°C with more conventional fuels such as hydrocarbon or alcohol are actively studied for overcoming the limitations of high temperature SOFC, e.g., durability, cost, and limited application. Therefore, the necessity of improving the performance and stability of Ni-based anode is aroused because it shows relatively slow hydrocarbon and alcohol oxidation kinetics in the low-temperature regime and vulnerable to carbon deposition. To improve kinetics and stability of Ni-based anode upon hydrocarbon fuel-based operation, various kinds of metal catalysts, e.g., copper, palladium, iron, etc., have been applied using fabrication techniques such as wet synthesis, infiltration, vapor deposition, etc. In this study, ruthenium (Ru) having high catalytic activity and carbon coking toleration is applied to Ni-based cermet anode used in methane-fueled low-temperature SOFC. In particular, atomic layer deposition (ALD), which can deposit nanoparticles conformally on porous structures, is used for depositing Ru nanoparticles on nano-structured Ni-based cermet anode. ALD Ru nanoparticles fabricated in such a way are well-dispersed on the surface of Ni-based cermet anode and effectively improve the performance and stability of the anode when it is operated with methane-fuel. Especially, Ni-based anode with optimal ALD Ru thickness, i.e., 10nm in thickness, shows 40% higher maximum power density than those without ALD Ru overcoating when operated with methane fuel.