M.T. Mehran, R-H Song, T-H Lim, S-B Lee, J-W Lee, S-J Park
Korea Institute of Energy Research, Korea
pp. 98 - 101
Keywords: solid oxide fuel cell, degradation, anode support, mechanical strength, Al2O3
Solid oxide fuel cells are well known to be highly efficient and clean energy conversion devices for stationary and portable power generation. The ceramics based SOFC’s operate at high temperatures (>700 °C) and the durability of SOFC is critical for the early commercialization of SOFC based systems. Anode support of the SOFC becomes vulnerable to severe degradation during the long-term operation due the thermal stresses, humid and reducing environment, and the threat of redox-cycling. The mechanical strength of the nickel-yttria-stabilized zirconia (Ni-YSZ) anode supports needs to be assessed and improved for a durable SOFC. In this study, we developed a highly durable Ni-3YSZ based anode support material for SOFC with higher mechanical strength and stability. At first, the strength and mechanical properties of the typical Ni-3mol% yttria-stabilized zirconia (Ni-3YSZ) and Ni-8mol% yttria-stabilized zirconia (Ni-8YSZ) were assessed during 1000h long-term degradation test. It was found that after 1000 h, the flexural strength of the Ni-3YSZ anode support cermet was decreased up to 57%. Therefore, the mechanical properties of Ni-3YSZ anode support were improved by the addition of dispersed nano-particles of Al2O3. Different amounts of nano-Al2O3 were added and their effect on long-term stability was studied. The anode support with 3wt. % nano-Al2O3 dispersed Ni-3YSZ (Al-Ni-3YSZ) showed only 18% degradation in the mechanical strength. Further analysis by SEM and XRD before and after the long-term degradation test showed that the tetragonal to monoclinic phase transformation in zirconia was reduced due to the addition of nano-Al2O3 in Ni-3YSZ cermet, resulting into an improved long-term stability and higher mechanical strength. The nano-oxide dispersed Ni-3YSZ anode support showed superior mechanical strength after 1000h long-term test and can be used to fabricate a durable SOFC promising structural integrity to fuel cell stack over the lifetime.