A porous yttria-stabilized zirconia layer to eliminate the delamination of air electrode in solid oxide electrolysis cells

Abstract

Abstract Delamination of La 0.8 Sr 0.2 MnO 3-δ (LSM) in solid oxide electrolysis cells (SOECs) is usually associated with the high oxygen partial pressure build-up at the LSM-YSZ (yttria-stabilized zirconia) interface. Here we sandwich a porous YSZ layer between the LSM electrode and YSZ electrolyte to release this oxygen pressure. Symmetric cells with and without the porous YSZ layers are prepared and tested in air at 800 °C under the current densities of 0.5 and 1 A cm −2 for 100 h. Voltage change is continuously monitored, and impedance spectrum studies have been carried out before and after testing. No delamination has been observed for the samples with the porous YSZ layer even after 100 h. The improved performance for these samples is due to the shift of oxygen evolution reaction from the dense YSZ-LSM interface to a porous YSZ-LSM interface. This shift also helps the oxygen to be easily released instead of going into the pores or grain boundaries of the electrolyte. On the other hand, for the sample without the porous YSZ layer, the LSM is totally delaminated from the electrolyte just after 70 h.