Enhancement in Chemical Stability of Proton Conducting Solid Oxide Electrolysis Cell (SOECs)
Authors: Park Jun-Young , Saqib Muhammad , Park Ka-Young , Lee Tae-Hee 
Published: February 2020

Developments of fuel cell technology are a great achievement for researcher’s to fulfill the need of clean and renewable energy. Among the various type of fuel cells, high temperature ceramic fuel cells inherit several advantages such as high efficiency, fuel flexibility and no precious-metal catalyst [1], but the solid oxide fuel cell (SOFC) typically uses yttria-stabilized zirconia (YSZ) at operating temperature of 800-1000°C, resulting in high cost, cell degradation and material compatibility issues.

Many researchers investigated protonic ceramic conducting fuel cells (PCFCs) and have presented their possibility as intermediate temperature ceramic fuel cells [2, 3]. Proton-conducting oxides due to high conductivity with lower activation energy (0.3-0.6eV) can be operated at lower temperature of 400-600°C, which increases the cell life-time and reduces the fabrication cost. Compared with SOFCs when operating on hydrocarbon fuel, particularly CH4 conversion rate is high due to direct conversion of proton (hydrogen).

A few studies try to use solid oxide electrolysis cell (SOEC) to produce hydrogen by electrolyzing steam at the IT range. [4]. In conventional oxygen-ion SOECs, steam is fed into the fuel electrode side, then the oxygen-ions move toward the air electrode, while the hydrogen is produced at fuel electrode side. One of the technical issues in SOECs is the oxidation of Ni based electrode in steam conditions, resulting in cell degradation. In proton-conducting SOECs, steam is fed at air electrode and hydrogen is produced at fuel electrode. In IT-SOFCs, the BSCF cathode is considered to be as an excellent material [5], but it can be degraded and decompose in high humid air condition. Hence, we should develop durable materials against high water vapor pressure.

In this study we design the electrode material to develop highly durable cathode materials for SOECs. Moreover, in order to investigate the practical use of these cell, the accelerating durability test is designed and carried out. The durability test is conducted by periodically repeated both in fuel cell and electrolysis modes. To find the degradation analysis of the cell, micro-structural analysis is performed with SEM, TEM and XRD [6, 7], the impedance spectra and over-potential analysis are performed.

E. D. Wachsman, and K. T. Lee, Science
,
334, 935 (2011).

C. Duan, J. Tong, M. Shang, S. Nikodemski, M. Sanders, S. Ricote, A. Almansoori and R. O’Hayre, Science, 349, 6254 (2015).

L. Bi, S. Boulfrad and E. Traversa, J. Chem. Soc. Rev.,
43, 8255 (2014).

M. Ni, M. K. H. Leung and D. Y.C. Leung, Int. Ass. Hydrogen Eng., 33, 4040 (2008).

P. K. Lohsoontorn, D. J. L. Brett, N. Laosiripojana, Y. M. Kim, J-M. Bae, Int.
J.
Hydrogen energy, 35, 3958 (2010).

G. Kim, N. Lee, K. -B. Kim, B. -K. Kim, H. Chang, S. J. Song, J. -Y. Park, Int.
J.
Hydrogen energy, 38, 1571 (2013).

H. Xiao, T. L. Reitz, M. A. Rottmayer, J. Power sources, 183, 49 (2008).

* Corresponding authors: jyoung@sejong.ac.kr (J.-Y. Park)