Effect of A site deficiency of LSM cathode on the electrochemical performance of SOFCs with stabilized zirconia electrolyte

Abstract

The effect of A site deficiency on the electrochemical performance of a strontium-doped lanthanum manganite (LSM) cathode in an ScSZ electrolyte-supported solid oxide fuel cell (SOFC) was investigated. XRD characterization resulted in a series of (La0.75Sr0.25)xMnO3 (x=1.0, 0.97, 0.95, 0.9 and 0.85) powders, indicating that the Mn3O4 phase precipitated into (LS)xM when the deficiency value was over a certain threshold value. The chemical reaction occurred between stoichiometric LSM and ScSZ due to the high chemical potential of La. An A site deficiency in the LSM can reduce the chemical potential of La and suppress the interfacial reaction between the LSM and ScSZ. The precipitation of Mn3O4 due to a larger A site deficiency leads to the formation of LZO occurring at the A site-deficient (LS)xM and ScSZ. An A site-deficient (LS)xM cathode appears to possess good adhesion with the ScSZ electrolyte and a longer active TPB length after being sintered at 1300°C. An optimal A site deficiency concentration was considered to exist in the electrochemical performance improvement of the A site-deficient LSM cathode SOFC.