Synthesis and electrochemical characterization of Sr_2Fe_(1.5)Mo_(0.5)O_6-Sm_(0.2)Ce_(0.8)O_(1.9) composite cathode for intermediate-temperature solid oxide fuel cells

摘要

Nanoporous composite oxides Sr_2Fe_(1.5)Mo_(0.5)O_6-Sm_(0.2)Ce_(0.8)O_(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 (Y_2O_3-stabilized ZrO_2) 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 ℃, and R_p is only 0.11 Ω cm~2. Compared with single cells without an interlayer, the anode-supported single cells with SDC interlayer exhibit enhancement in overall power performance.