Activation and failure mechanism of La0.6Sr0.4Co0.2Fe0.8O3−Δair electrode in solid oxide electrolyzer cells under high-current electrolysis

Zehua Pan, Qinglin Liu, Meng Ni, Renzhi Lyu, Ping Li, Siew Hwa Chan

Research output: Journal article publicationJournal articleAcademic researchpeer-review

14 Citations (Scopus)

Abstract

This work investigates the activation and delamination of La 0.6Sr 0.4Co 0.2Fe 0.8O 3−δ (LSCF) air electrode of solid oxide electrolyzer cells sintered on yttria-stabilized zirconia (YSZ) electrolyte. After polarization with an electrolysis current of 1 A cm −2 for 24 h at 800 °C, the LSCF electrode delaminates accompanied by an increase of ohmic and polarization resistance. Notably, polarization resistance decreases at the beginning. By scanning electron microscopy (SEM), a thin but dense layer is observed at the LSCF–YSZ interface of an as-prepared sample, which is identified as SrZrO 3 phase by X-ray diffractometry. This layer causes the initial high polarization resistance due to retarded ionic and electronic conductivity. After the test, SEM reveals that the SrZrO 3 layer delaminates from YSZ electrolyte. Moreover, energy dispersive X-ray tests confirm that Co diffuses to the SrZrO 3 layer and SrZrO 3–YSZ interface. Later, the LSCF electrode with Co-containing SrZrO 3 layer is shown to perform better than that with pure SrZrO 3 layer. Thus, Co diffusion can be the reason for the initial decrease of polarization resistance and renders the generation of oxygen at SrZrO 3–YSZ interface during the electrolysis. Owing to its limited porosity, the SrZrO 3 layer traps the generated oxygen. High pressure eventually builds up at the SrZrO 3–YSZ interface driving the delamination of SrZrO 3 layer, and hence the entire LSCF electrode.

Original languageEnglish
Pages (from-to)5437-5450
Number of pages14
JournalInternational Journal of Hydrogen Energy
Volume43
Issue number11
DOIs
Publication statusPublished - 15 Mar 2018

Keywords

  • Activation of air electrode
  • Co diffusion
  • Delamination of air electrode
  • La Sr Co Fe O air electrodes
  • Solid oxide electrolyzer cell

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

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