Effects of a YSZ porous layer between electrolyte and oxygen electrode in solid oxide electrolysis cells on the electrochemical performance and stability

• Published in: International journal of hydrogen energy Vol. 44; no. 29; pp. 14493 - 14499
• Main Authors: Su, Chaoxiang, Lü, Zhe, Wang, Chaoqi, Li, Jingwei, Li, Pengzhang, Yue, Xing, Li, Huan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 07-06-2019
• Subjects: Chronopotentiometry; Distribution of relaxation time; LSM oxygen electrode; Oxygen pressure; YSZ porous layer; Chronopotentiometry; Oxygen pressure; YSZ porous layer; Distribution of relaxation time; LSM oxygen electrode
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2019.04.092

The delamination of (La,Sr)MnO3 (LSM) oxygen electrode is considered as a key reason for the degradation of solid oxide electrolysis cells (SOEC). In this study, a YSZ porous layer prepared by spinning coating has been introduced to inhibit significant degradation of LSM oxygen electrode during anodic polarization for 100 h under constant 500 mA cm−2. Impedance spectra of LSM oxygen electrode are recorded before and after anodic polarization. By performing distribution of relaxation time (DRT) processing on the impedance spectra, it is indicated that the introduction of YSZ porous layer provides more active sites or three phase boundary (TPB) for oxygen oxidation reaction. The potential relaxation process of LSM oxygen electrode is measured by three-sequence chronopotentiometry. The result proves that the sample with a YSZ porous layer has lower the oxygen activity and faster the oxygen ion diffusion at the solid-solid two-phase (oxygen electrode and electrolyte) interface (SSTPI) due to more TPB and shorter oxygen ion diffusion paths.
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•The YSZ porous layer improves stability of LSM oxygen electrode in SOEC.•The YSZ porous layer increases three phase boundary.•Three-sequence CP is used to evaluate the potential relaxation process.