Fast Fabrication of SOFCs with Screen-Printed YSZ Electrolyte Films By Flash Light Sintering
Authors: Lim Yonghyun , Lee HoJae , Park Jung-hum , Park Jun-Sik , Kim Young-Beom 
Published: February 2020

Solid oxide fuel cells (SOFCs) are attractive energy conversion system because of their high energy conversion efficiency, fuel flexibility and no emission of pollutant. SOFCs are composed of a dense electrolyte and two porous electrodes of anode and cathode. In the fabrication of SOFCs, many fabrication techniques such as screen-printing, tape casting, sol-gel, sputtering, chemical vapor deposition (CVD) and atomic layer deposition (ALD) are used to fabricate the solid electrolyte and the electrodes. Among various fabrication techniques, screen-printing is most widely used method in the industry because it is easy, scalable and economical process.

Meanwhile, for the fabrication of solid electrolyte in this technique, high temperature sintering process is essential because the electrolyte should be fully densified to prevent any penetration of electrons and fuels. However, this high process temperature takes a considerable amount of time and thus causes significant manufacturing costs. Therefore, reducing the sintering temperature and long process time is one of the major challenges to reduce the fabrication cost and facilitate the commercialization of SOFCs.

In recent years, to address these issues, many researchers demonstrated alternative sintering processes to reduce the sintering temperature and process time. For example, several researchers proposed rapid thermal annealing (RTA) process as an alternative sintering process because it can raise temperature to the target temperature within short time [1,2]. However, this process still requires relatively long maintaining and cooling processes. In addition, the excimer laser ablation annealing and the microwave sintering process have been also suggested but there are still limitations such as extremely narrow spot size and complexity of microwave interactions with materials respectively [3,4].

On the other hand, the flash light sintering process presented here uses white light flash irradiation with a broad visible wavelength range as a heat treatment source and this process has many advantages such as simplicity, scalability, and cost-effectiveness. Above all, because this process conducted within a few seconds at room temperature under ambient conditions, it can effectively reduce the manufacturing time and cost. Our previous works successfully demonstrated that the YSZ thin films deposited by solution-based process was annealed by flash light sintering and it showed comparable material properties to the conventional thermal sintering process [5].

In this work, the YSZ electrolyte films were fabricated by conventional screen-printing method and flash light sintering process was employed as an alternative sintering process of conventional thermal sintering method. In the sintering process, the effect of various pulse conditions and additional substrate heating were investigated. Microstructure, crystallinity and sintering behaviors of sintered films were analyzed to demonstrate the effectiveness of flash light sintering process.

Reference

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[2] Beltrán, N. H., Balocchi, C., Errazu, X., Avila, R. E. & Piderit, G. Rapid thermal annealing of zirconia flms deposited by spray pyrolysis. Journal of Electronic Materials 27, L9–L11 (1998).

[3] Hao, H., Xu, L., Huang, Y., Zhang, X. & Xie, Z. Kinetics mechanism of microwave sintering in ceramic materials. Science in China Series E: Technological Sciences 52, 2727–2731 (2009).

[4] Bayati, R. et al. Modifcation of properties of yttria stabilized zirconia epitaxial thin flms by excimer laser annealing. ACS applied materials & interfaces 6, 22316–22325 (2014).

[5] Park, J.S. et al. Rapid, cool sintering of wet processed yttria-stabilized zirconia ceramic electrolyte thin films. Scientific reports 7, 12458 (2017)