Characterization of La0.5Sr0.5Co0.5Ti0.5O3−δ as symmetrical electrode material for intermediate-temperature solid-oxide fuel cells

La0.5Sr0.5Co0.5Ti0.5O3−δ perovskite oxide has been prepared as polycrystalline powder, characterized and tested as cathode and anode material for solid-oxide fuel cells. The oxidized material is suggested to present mixed ionic-electronic conductivity (MIEC) from “in-situ” neutron powder diffraction (NPD) experiments, complemented with transport measurements; the presence of a sufficiently high oxygen deficiency, with large displacement factors for oxygen atoms suggest a large lability and mobility combined with a semiconductor-like behaviour with a maximum conductivity of 29 S cm−1 at T = 850 °C. A complete reversibility towards reduction–oxidation processes has been observed, where the reduced Pm-3m perovskite with La0.5Sr0.5Co0.5Ti0.5O2.64 composition has been obtained by topotactical oxygen removal without abrupt changes in the thermal expansion. The oxidized material shows good performance working as a cathode with LSGM electrolyte, yielding output power densities close to 500 mW/cm2 at 850 °C. At intermediate temperatures (800 °C) it may be used as a cathode or as an anode, yielding power densities of 220 and 170 mW/cm2, respectively. When used simultaneously as cathode and anode a maximum power density of 110 mW/cm2 was obtained. Therefore, we propose the La0.5Sr0.5Co0.5Ti0.5O3−δ composition as a promising candidate for symmetrical electrode in intermediate-temperature SOFC.

► Novel mixed ionic electronic conductor perovskite. ► Reversibility upon oxidation–reduction cycles. ► Promising candidate for symmetrical electrode in intermediate-temperature SOFC.