Fabrication of Nano Samarium Doped Ceria(SDC) Infiltrated La6Sr4Co2Fe8O3-δ(LSCF) Composite Cathode for High Performance It-SOFCs

Abstract

The solid oxide fuel cells(SOFCs) use oxygen ions generated by an oxygen reduction reaction(ORR) supplied to the cathode as charge carrier. Oxygen ions transferring across the solid oxide electrolyte via a hoping mechanism require a high operating temperature to overcome the low ionic conductivity. High ionic conductivity and performance can be obtained at high operating temperature, but the stability is reduced during operation condition due to deterioration of component materials and mutual chemical reactions at the interface. For this reason, researches have proceeded to lower operating temperature of to the intermediate temperature regime(650~750℃) and to develop the electrode layers having high performance at the lower operating temperature. However, since the oxygen reduction reaction resistance is increased, the performance of the SOFCs is reduced at the lower operating temperature. Therefore, many research institutes of fuel cells have added the composite cathode functional layer(CFL) to improve the fuel cell performance between electrolyte and electrode layers using various methods, composite powder, and infiltration. [1, 2] In this study, the solid oxide fuel unit cells are fabricated having the electrolyte/electrode composite layer which was applied to the LSCF electrode infiltrated with nanoparticle SDC for obtaining the many reaction site compared with conventional powder composite materials. When the LSCF-SDC composite cathode functional layer is manufactured, it is applied that the novel flash light sintering method replace the conventional thermal sintering method. Since it can finish the manufacturing process in seconds, the LSCF-SDC cathode layer has the LSCF cathode with nanoparticle SDC suppressed grain growth of the particles which can contribute to improving the performance of the fuel cells.[3] The microstructure of the infiltrated solution and the composite layer of the electrolyte material is analyzed using scanning electron microscopy (FE-SEM) and transmission electron microscopes energy dispersive spectroscopy (TEM-EDS). The crystallinity of nanoparticle SDC is analyzed using FR-TEM and X-ray diffraction. And, the electrochemical analysis of LSCF-SDC cathode cell is carried out at 650~750°C. The performance improvement of the solid oxide fuel cell at intermediate operating temperature is maximized through the fabrication of the cathode functional layer using the solution infiltration method and the alternative flash light sintering process. Reference [1] J. Hong, A. Bhardwaj, Y. Namgung, H. Bae, S.-J. Song, Evaluation of the effects of nanocatalyst infiltration on the SOFC performance and electrode reaction kinetics using the transmission line model, Journal of Materials Chemistry A, 8 (2020) 23473-23487.[2] J. Shin, S. Yang, H.-I. Ji, S. Park, H. Kim, J.-W. Son, J.-H. Lee, B.-K. Kim, J. Hong, K.J. Yoon, Low-temperature processing technique of Ruddlesden-Popper cathode for high-performance solid oxide fuel cells, Journal of Alloys and Compounds, 868 (2021) 159092.[3] Y. Lim, J. Park, H. Lee, M. Ku, Y.-B. Kim, Rapid fabrication of lanthanum strontium cobalt ferrite (LSCF) with suppression of LSCF/YSZ chemical side reaction via flash light sintering for SOFCs, Nano Energy, 90 (2021) 106524.