Synthesis and characterization of LaCoO₃ based cathode and its chemical compatibility with CeO₂ based electrolytes for intermediate temperature solid oxide fuel cell (ITSOFC)

Abstract

The use of alternate cathode materials with improved performance and without any chemical reaction with adjoining electrolyte is required for a reduction in operating temperature of SOFC from 1273 K to about 1073 K (ITSOFC). Cobalt containing perovskite oxides such as LaCoO₃ tend to exhibit a higher ionic conductivity due to a greater concentration of oxygen vacancies than other perovskite oxides. The mixed ionic and electronic conducting cathode of the La₁₋xSrxCoO₃₋δ systems has shown the lowest cathodic overpotential for an SOFC air electrode. In this research work, fine powders of La₀․₇₀Sr₀․₃₀CoO₃₋δ (LSC) cathode and Ce₀․₉₀Gd₀․₁₀O₂₋δ (GDC) and Ce₀․₈₀Sm₀․₂₀O₂₋δ (SDC) are synthesized by glycine nitrate combustion synthesis and systematically characterized by XRD and particle characteristics. The electrical properties of LSC cathode and GDC and SDC electrolytes are also studied. But, the crucial requirement for applicability of LSC cathode is its chemical compatibility in conjunction with the alternate solid electrolytes, GDC and SDC without any phase formation. The XRD studies showed no reaction products when the La₀․₇₀Sr₀․₃₀CoO₃₋δ cathode is mixed and calcined with GDC and SDC electrolyte at 1573 K. Hence, the LSC cathode may be combined with CeO₂ based electrolytes in ITSOFC application.