Thursday, 4 October 2018: 10:20
Universal 22 (Expo Center)
S. S. Shin (Seoul National University, Korea Institute of Science and Technology), J. Kim, J. Choi, C. Lee (Seoul National University), H. Kim (Korea Institute of Science and Technology), J. W. Son (Korea Institute of Science and Technology (KIST)), H. Shin, and M. Choi (Seoul National University)
As an environmentally friendly future power source, the Solid Oxide Fuel Cells (SOFCs) have several attractive advantages such as high efficiency of direct conversion from chemical energy to electric, reduced over-potential losses and an application of non-precious metal catalyst for electrodes due to high operating temperature (> 800 °C). In contrast, this high operating temperature of SOFCs results in main issues including higher system cost and rapid cell degradation rate which limits practicality of SOFCs for commercial applications such as portable device. The most recently, the electrolyte material, Er
0.4Bi
1.6O
3 (ESB) with exceptionally high ionic conductivity (0.027 S/cm at 500 °C) was developed to lower the operating temperature. However, their applications are limited by inter-diffusion reaction with cobalt-based perovskite catalyst such as La
0.6Sr
0.4CoO
3-δ (LSC), known as a conventional and highly active for materials for oxygen reduction reaction and severe weakness in reducing atmosphere.
In this study, we suggest a novel architecturing method to utilize ESB along with LSC for superior electrochemical performance. For this, we used Ce0.9Gd0.1O1.95 (CGO) and ESB as dense electrolyte and barrier electrolyte to prevent current leakage through CGO. Anode support with a thickness of 1 mm was fabricated by tape casting method. CGO and ESB were deposited on the anode support by screen printing and polymer-assisted electrospray deposition (PA-ESD) method, respectively. To achieve the compatibility of ESB with LSC, we suggested bi-walled nanotube structure cast by polycarbonate (PC) template. Ln-doped ceria (Ln: Ga or Sm) sol spread on the PC template inner surface enter into the cylindrical hole of PC due to the capillary force. After the gelation, the Ln-doped ceria sol converges to the wall surface to form a perforated cylinder. The same procedure was repeated with LSC sol, resulting in bi-walled nanotube after sintering. In this case, Ln-doped ceria not only blocks the reaction pathway between the LSC and the ESB but can lead to improved performance from extended reaction area obtained from the multiscale structure. In conclusion, our study shows that the novel architecturing method opens the possibility of expanding the range of materials selection for low-temperature SOFCs.
