Synthesis and electrochemical characterization of Sr2Fe1.5Mo0.5O6-Sm0.2Ce0.8O1.9 composite cathode for intermediate-temperature solid oxide fuel cells

Nanoporous composite oxides Sr2Fe1.5Mo0.5O6-Sm0.2Ce0.8O1.9 (SFM-SDC) have been prepared by a facile one-step method as cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The SFM-SDC composite materials have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and electrochemical impedance spectroscopy (EIS). The EIS results exhibit that SFM-SDC40 (wt% 60:40) cathode has encouraging electrochemical performance with low polarization resistance (Rp) on YSZ (Y2O3-stabilized ZrO2) electrolyte. Subsequently, bi-layer cathodes SDC/SFM-SDC are fabricated, and excellent electrochemical performance of such composite cathodes are observed. We demonstrate that the SDC interlayer significantly decreases the Rp of cathode and accelerates the charge transfer process. As a result, the Rp of the SDC/SFM-SDC40 bi-layer cathodes is almost 50% less than that of SFM-SDC40 cathode on YSZ electrolyte at 800 °C, and Rp is only 0.11 Ω cm2. Compared with single cells without an interlayer, the anode-supported single cells with SDC interlayer exhibit enhancement in overall power performance.