The degradation mechanism of La_0.6Sr_0.4Co_0.2Fe_0.8O_{3 − δ} (LSCF) electrode is investigated by examining its electrochemical behavior under equilibrium potential at elevated temperature and corresponding surface compositional changes. Diluted nitric acid etching treatment is conducted to confirm the correlation between the surface changes and the variation of electrochemical performance. It has been shown that the increase of polarization resistance of LSCF electrode has a linear dependence on the square root of time and arises from degradation of mass transfer process taking place at the gas-solid interface of electrode, such as oxygen adsorption/desorption and surface diffusion. Comparison of the behavior of the electrode before and after nitric acid treatment shows that the presence of surface inhibited species can account for the above observations. This inhibited species is confirmed by X-ray photoelectron spectroscopy to be a surface segregated Sr-based material, which supports the claim that surface Sr segregation is detrimental. A further lifespan study of LSCF electrode up to 158 h under 1 A/cm² electrolysis current demonstrates that the current can improve and stabilize the performance, which could be ascribed to the removal of surface Sr species due to the incorporation of surface Sr back into the lattice of LSCF.

Lanthanum strontium manganese chromite, (La_0.75Sr_0.25)Cr_0.5Mn_0.5O₃ (LSCM), perovskite oxides were synthesized by gel-casting and solid-state reaction techniques as electrode materials of solid oxide fuel cells (SOFCs). Thermal and XRD analyses indicate that the phase formation temperature of LSCM powders synthesized by the gel-casting technique is 50–100 °C lower than that by the solid-state reaction method. The LSCM/YSZ composite electrode prepared using the gel-casting LSCM powder is shown to have a much higher electrochemical activity for the O₂ reduction and H₂ oxidation reactions than that using the solid-state reaction powder. The reason for this is most likely related to the homogeneously distributed and immobilized precursor particles in a polymeric network, forming micro-scale interconnected networks. The results in the present study demonstrate the advantages of the aqueous gel-casting method in the synthesis of high quality and highly catalytic active LSCM oxide powders for SOFCs. Finally, a novel symmetric LSCM/YSZ composite anode and LSCM/YSZ composite cathode-supported thin-electrolyte cell is fabricated and demonstrated.