High conductivity mixed oxide-ion and carbonate-ion conductors supported by a prefabricated porous solid-oxide matrix

A novel two-phase mixed oxide-ion and carbonate-ion conductor (MOCC) has been recently developed for intermediate temperature solid-oxide fuel cells and CO2 separation membranes. With conventional mixing–pressing ceramic fabrication technique it is difficult to obtain a MOCC with high mechanical strength and high oxide-ion conductivity due to the low sintering temperature. In this study, a samarium doped ceria (SDC, Ce0.8Sm0.2O1.9) is selected to demonstrate the prefabrication of porous matrix by the “sacrificial template” methodology with Ni as the template material. The microstructure of the SDC matrix characterized with a 3D X-ray computed tomography and a SEM imaging reveals a uniform distribution of homogeneous micro-pores across the solid-oxide matrix. A Li–Na-carbonate-impregnated MOCC supported by a 40% porous SDC matrix shows an effective ionic conductivity of 0.55 and 0.46 S/cm at 650 and 600 °C, respectively, the highest values reported so far among similar systems.

Research highlights
► Highest ionic conductivity.
► Porous oxide matrix.
► Infiltration of carbonate.
► 3D images.