Synthesis and electrochemical characterization of Sr₂Fe _1.5Mo_0.5O₆-Sm_0.2Ce _0.8O_1.9 composite cathode for intermediate-temperature solid oxide fuel cells

Nanoporous composite oxides Sr₂Fe_1.5Mo _0.5O₆-Sm_0.2Ce_0.8O_1.9 (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 (R_p) on YSZ (Y₂O ₃-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 R_p of cathode and accelerates the charge transfer process. As a result, the R_p 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 R_p 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.