Preparation of (Ba,Sr)_(0.5)Sm_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) and (Ba,Sr)_(0.5)Nd_(0.5)C_(0.8)Fe_(0.2)O_(3-δ) cathodes for IT-SOFCs

摘要

The development of electrochemical devices towards clean energy generation has been intensified in the last years. In this context, fuel cells, and especially intermediate temperature solid oxide fuel cells (IT-SOFC) have received much attention. Perovskite-type materials of composition Ba_(1-x)Sr_xCo_(1-y)Fe_yO_(3-δ), doped or not with rare earth ions, have been quite promising because they have good ionic conductivity and operate at relatively low temperatures (500-750 °C). In this study, powders of compositions (Ba,Sr)_(0.5)Sm_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) (BSSCF) and (Ba,Sr)_(0.5)Nd_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ) (BSNCF) were prepared using commercial gelatin powder as a polymerizing agent for its use as cathode. The as-prepared powders were calcined at 1000 °C and characterized by X-ray diffraction and scanning electron microscopy. Screen-printed symmetrical cells were sintered 1150 °C and studied by electrochemical impedance spectroscopy in order to assess the cathode kinetics for the oxygen reduction reaction. The results ASR for BSNCF at 650 °C and 750 °C were 1.318 and 0.208 Ω.cm~2, respectively, and for the BSSCF cathode was obtained 1.02 and 0.157 Ω.cm~2, respectively. Microstructural features, associated to good electrochemical performance, indicate that these perovskite materials are good candidates as intermediate temperature SOFC cathodes.