LaGaO3-based composite membrane with high oxygen permeability

This study presents the demonstration of the applicability of Sr and Mg co-doped LaGaO3 (LSGM), which is representative electrolyte material for solid oxide electrochemical cells due to its exceptional oxygen ionic conductivity, as oxygen transport membranes (OTMs). Herein, the oxygen flux of a LaGaO3-based composite membrane was systematically investigated by introducing Sr and Mg co-doped LaGaO3 as an ion-conductive material for composite membranes. To enhance the compatibility of the membrane and the surface exchange kinetics, perovskite LSCF phase containing La and Sr at the A-site was adopted as an electronic constituent in the membrane and active coating layer. Thus, the secondary phase between the two phases of the ionic and electronic conductors constituting the composite membrane was not observed. The highest oxygen flux (3.6 mL cm−2 min−1) was achieved in the LaGaO3-based membrane at 900 °C. The mechanism for enhancing the oxygen permeability via the active coating layer was confirmed by deriving the surface exchange kinetics under an operating atmosphere. These promising results indicate that LSGM represents a viable substitute for the oxygen-ion conductive materials utilized in dual-phase membranes.