Formation of a Nanostructured Samarium-Doped Ceria-Lanthanum Strontium Cobalt Ferrite Functional Composite Cathode/Current Collector Single Layer for High-Performance SOFCs

Abstract

High-temperature solid oxide fuel cells (SOFCs) typically operate at high temperatures to minimize oxygen reduction reaction resistance at the cathode and enhance oxygen ionic conductivity. To suppress performance degradation caused by the degradation of SOFC components, it is necessary to lower the operating temperature; however, lowering the operating temperature drastically reduces the performance of the fuel cell. The performance of the fuel cell deteriorates at intermediate and low operating temperatures (550-750 degrees C) due to reduced ionic conductivity and oxygen reduction reaction rates. Therefore, a cathode functional layer composed of both the electrolyte and cathode materials is essential to improve the performance at these intermediate temperatures. In this study, an electrode/electrolyte composite was fabricated through the infiltration of a samarium-doped ceria (SDC) electrolyte into a lanthanum strontium cobalt ferrite (LSCF) cathode layer with flash-light sintering (FLS). This approach secures more reaction sites compared to the conventional powder mixing of the cathode and electrolyte. In addition, the conventional thermal sintering process is replaced with a flash-light sintering process, which can be completed in a few seconds. This approach helps suppress the grain growth of the infiltrated SDC particles, thereby improving the performance of the SDC-infiltrated LSCF cathode (SDC-LSCF) functional layer cell. Consequently, a performance of 1.43 W/cm2 is achieved, representing a 40% improvement compared with that of an LSCF cell without infiltration at 750 degrees C. Moreover, the combined fabrication method of rapid sintering and solution infiltration enhances the electrochemical performance of SOFCs. These improvements can facilitate the commercialization of SOFCs by replacing conventional thermal sintering and lowering the operating temperatures.