Flash Light Sintered SOFC Cathode Functional Layer through Electrostatic Spray Deposition

Abstract

Solid oxide fuel cells(SOFCs), which are attracting attention as an eco-friendly power generation system, are being actively studied due to their fuel flexibility and high efficiency. Since the charge carriers are oxygen ions and have to pass through the solid oxide electrolyte, they require a higher operating temperature (~900 oC) than other fuel cells. To overcome the disadvantages of high-temperature operation, research is being conducted to lower the operating temperature of the SOFCs. In particular, in order to minimize performance degradation even at low operating temperatures, research is being conducted to fabricate cell components as thin films or to apply electrodes with high catalytic activity and large reaction areas.Among the methods of manufacturing thin films, the deposition method using chemical solution deposition(CSD) has the advantage of being cost effective and easily controllable compared to the vacuum deposition method. Electrostatic spray deposition(ESD), one of the CSD deposition methods, is simple to set-up and a variety of compounds can easily be made by controlling the proportions of the precursors. However, a characteristic of the CSD method is that a post heat treatment process is required to obtain desired properties, which consumes a lot of time and cost during the entire process. To solve this problem, processes such as rapid thermal annealing, microwave, and excimer laser ablation are being studied, but these processes have limitations in that they damage the substrate, have a long cooling time, and have a small sintering area. [1, 2] On the other hand, the flash light sintering method using a xenon lamp can perform a post-heat treatment process quickly at room temperature and atmospheric pressure using intense pulsed light, and has the advantage of minimizing damage to the substrate and being applicable to a large area. [3, 4]In this study, the cathode functional layer, which is closely related to the performance of SOFC, was fabricated using the ESD method, and the flash light sintering method was applied for the post-heat treatment process. By applying the flash light sintering method, the heat treatment process, which used to take tens of hours, was shortened to just a few seconds. The sintering behavior of the film produced by flash light sintering was confirmed by comparing the microstructure and crystallinity. In addition, it was confirmed that the film manufactured by flash light sintering worked successfully by comparing the performance with the cell manufactured by the conventional thermal sintering method. Reference [1] R. Bayati et al., "Modification of Properties of Yttria Stabilized Zirconia Epitaxial Thin Films by Excimer Laser Annealing," (in English), Acs Applied Materials & Interfaces, vol. 6, no. 24, pp. 22316-22325, Dec 24 2014.[2] H. S. Hao, L. H. Xu, Y. Huang, X. M. Zhang, and Z. P. Xie, "Kinetics mechanism of microwave sintering in ceramic materials," (in English), Science in China Series E-Technological Sciences, vol. 52, no. 9, pp. 2727-2731, Sep 2009.[3] J. S. Park, D. J. Kim, W. H. Chung, Y. Lim, H. S. Kim, and Y. B. Kim, "Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films," (in English), Scientific Reports, vol. 7, Sep 29 2017.[4] J. S. Park, H. Lee, S. Heo, and Y. B. Kim, "Heater-assisted intense pulsed light irradiation for lanthanum strontium cobaltite thin film electrode fabrication," (in English), Thin Solid Films, vol. 697, Mar 1 2020.