Interlayer modification for high-performance and stable solid oxide electrolysis cell

Abstract

Solid oxide electrolysis cells (SOECs) are an attractive technology that can convert energy into hydrogen or other syngas due to their high energy-conversion efficiency. To improve both performance and stability of SOECs, the effect of the interlayer modification between La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) air electrode and ytrria-stabilized zirconia (YSZ) electrolyte on the high-temperature water electrolysis performance was studied using electrochemical impedance spectroscopy at 1023 K under 40% H2O– 60% H2 fuel flow. Enhancement of the current density from 0.9 A/cm2 to 1.25 A/cm2 was achieved by replacing the porous Ce0.9Gd0.1O1.95 (GDC) interlayer by a dense GDC interlayer. Detailed analysis of the impedance spectra of the cell indicated that utilizing the dense GDC interlayer leads to a significant decrease of the ohmic resistance. Scanning electron microscopy-wavelength dispersive X-ray spectroscopy results show that the dense GDC interlayer could significantly reduce the secondary phase formation of SrZrO3 between the GDC and YSZ interface. Thus, the enhancement of the SOEC current density was also accompanied by good stability of the cell as confirmed over 50 h at 1023 K.