Multilayered LSC and GDC: An approach for designing cathode materials with superior oxygen exchange properties for solid oxide fuel cells

Highlights: • LSC and GDC thin films are prepared in multilayer nanostructures. • Multilayered LSC and GDC exhibit superior oxygen exchange properties. • Oxygen surface exchange coefficient k* values were in the order of 10⁻⁵ cm/s even at 500 °C. • Enhanced oxygen incorporation is attributed to interface-induced oxygen vacancies. • Cathodes suitable for intermediate-temperature solid oxide fuel cells are obtained. Cathode materials with significantly enhanced oxygen exchange properties are required to achieve high-performance solid oxide fuel cells (SOFCs). Here, it is shown that in multilayer heteroepitaxial films prepared by alternately stacking conventional mixed ionic and electronic conductors of (La_0.6Sr_0.4)CoO_3-δ (LSC) and gadolinia-doped ceria (GDC), extremely fast oxide ion incorporation and transport can be achieved at relatively lower temperatures. Multilayer LSC and GDC heteroepitaxial films prepared on YSZ electrolytes exhibit enhanced oxygen surface exchange coefficient (k*) values as compared to single LSC thin films. This is attributed to the existence of Ce³⁺ induced by the LSC-GDC interface, implying the presence of a relatively high density of oxygen vacancies which facilitate oxide ion incorporation and transport. Accordingly, unprecedented values of k* in the order of 10⁻⁵ cm/s were obtained for LSC-GDC multilayer thin film cathodes even at a relatively low temperature of 500 °C. The results here conclusively show that leveraging the effect of heterointerfaces through multilayering can be a viable approach to achieving superior cathode materials with enhanced oxygen exchange properties.