Investigation of structural and electrochemical properties of LaSrCo_1−xSb_xO₄ (0≤x≤0.20) as potential cathode materials in intermediate-temperature solid oxide fuel cells

The structural and electrochemical properties of the layered perovskite oxides LaSrCo_1−xSb_xO₄ (0≤x≤0.20) were investigated to study the effects of substituting Sb for Co for application as cathode materials in intermediate temperature solid oxide fuel cells (IT-SOFCs). The results of crystal structure analyses show the maximum content of Sb in LaSrCo_1−xSb_xO₄ to be 0.05 as a pure single phase. XPS shows that Co and Sb in LaSrCo_0.95Sb_0.05O₄ may possess mixed-oxidation states. The electrical conductivity increased greatly after Sb substitution. An improvement in the cathode polarization (R_p) values is observed from the Sb-doped sample with respect to the undoped samples. For example, R_p of LaSrCo_0.95Sb_0.05O₄ on LSGM was observed to be 0.16 Ω cm² at 800 °C in air. The main rate-limiting step for LaSrCo_0.95Sb_0.05O₄ cathode is charge transfer of oxygen atoms. These results indicate that Sb can be incorporated into LaSrCo_1−xSb_xO₄ based materials and can have a beneficial effect on the performance, making them potentially suitable for use as cathode materials in IT-SOFCs. - Graphical abstract: The oxygen partial pressure dependence of polarization resistances for a new layered perovskite cathode LaSrCo_0.95Sb_0.05O₄ at various temperatures was measured. - Highlights: • The maximum content of Sb was 0.05 mol in LaSrCo_1−xSb_xO₄. • The maximum electrical conductivity is 194 S cm⁻¹for LaSrCo_0.95Sb_0.05O₄ at 800 °C. • A rate-limiting process of charge transfer presented.