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Solid oxide fuel cells are promising renewable energy devices due to their high efficiency and fuel flexibility. As they operate at a higher temperature than other fuel cells, ceramic materials, such as perovskite-based La 0.6 Sr 0.4 CoO 3 and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 , can be used as electrodes to replace expensive noble metals. However, when the corresponding electrode and yttria-stabilized zirconia electrolyte are sintered together, SrZrO 3 produced from a side reaction acts as an insulator and deteriorates the performance of the fuel cell. Thus, the dense functional layer of a ceria-based material should be introduced between the electrode and the electrolyte to suppress the formation of secondary phases. However, in the conventional cell manufacturing process, it is challenging to manufacture a dense functional layer under constrained sintering conditions. In this study, we develop a method for fabricating a dense gadolinia-doped ceria (GDC) functional layer, even under constrained sintering conditions, by using a sacrificial bismuth oxide, Bi 2 O 3 , sintering aid layer above the GDC layer. As thermal sintering progresses at 1000–1200 °C, the Bi 2 O 3 sintering aid layer is sublimated, leaving only the pure GDC functional layer. The fabricated dense GDC functional layer characterized by various analysis methods shows improved solid oxide fuel cell performance. [ABSTRACT FROM AUTHOR]

• Screen printed LSCF-GDC composite cathode functional layer was fabricated for IT-SOFCs. • A novel, ultra-fast flash light irradiation was demonstrated as an alternative sintering method. • Interfacial side reactions were successfully suppressed by the novel process. • The maximum power density was 727.4 mW/cm2 at 750 °C. A solid oxide fuel cell (SOFC) requires an elevated operating temperature to achieve high oxygen ion conductivity and the oxygen reduction reaction (ORR). However, at high operating temperatures above 800 °C, performance deteriorates due to the chemical reaction of the electrode and electrolyte materials at the interface. Therefore, it is necessary to lower the operating temperature to the intermediate temperature regime while maintaining the high oxygen reduction reaction kinetics. One approach is adopting the composite cathode material such as La 6 Sr 4 Co 2 Fe 8 O 3-δ -gadolinium doped ceria (LSCF-GDC). However, the high temperature in the fabrication process results in non-conduction material of strontium zirconate (SrZrO 3 , SZO) layers at the cathode/electrolyte interface, which blocks oxygen ion conduction and degrades the fuel cell performance. By utilizing the novel flash light sintering process, which can be completed in a few seconds, high temperature fabrication issues are solved. The surface microstructure and thickness of the composite electrode are inspected using a scanning electron microscope (FE-SEM). The secondary phase generation and chemical reaction are analyzed using XRD (X-ray diffraction), SEM-EDS, and TEM-EDS. The anode supported LSCF-GDC cathode cells are measured from 600 °C to 750 °C. The maximum power density at 750 °C of the novel flash light sintered LSCF-GDC composite cathode cell is 727.4 mW/cm2. In addition to the utilization of high performing cathode structure, the flash light sintering process dramatically reduces the process time and suppresses the side reaction at the cathode/electrolyte interface. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) have strong potential for next-generation energy conversion systems. However, their high processing temperature due to multi-layer ceramic components has been a major challenge for commercialization. In particular, the constrained sintering effect due to the rigid substrate in the fabrication process is a main reason to increase the sintering temperature of ceramic electrolyte. Herein, we develop a bi-layer sintering method composed of a Bi 2 O 3 sintering sacrificial layer and YSZ main electrolyte layer to effectively lower the sintering temperature of the YSZ electrolyte even under the constrained sintering conditions. The Bi 2 O 3 sintering functional layer applied on the YSZ electrolyte is designed to facilitate the densification of YSZ electrolyte at the significantly lowered sintering temperature and is removed after the sintering process to prevent the detrimental effects of residual sintering aids. Subsequent sublimation of Bi 2 O 3 was confirmed after the sintering process and a dense YSZ monolayer was formed as a result of the sintering functional layer-assisted sintering process. The sintering behavior of the Bi 2 O 3 /YSZ bi-layer system was systematically analyzed, and material properties including the microstructure, crystallinity, and ionic conductivity were analyzed. The developed bi-layer sintered YSZ electrolyte was employed to fabricate anode-supported SOFCs, and a cell performance comparable to a conventional high temperature sintered (1400 °C) YSZ electrolyte was successfully demonstrated with significantly reduced sintering temperature (<1200 °C). [ABSTRACT FROM AUTHOR]