Performance optimization of SrFe0.95Ti0.05O3−δ cathode for intermediate temperature SOFC

Abstract

Fe-based perovskite oxide SrFe0.95Ti0.05O3−δ (SFT5) is developed as cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Single-phase SFT5 solid solution is obtained by sintering the sample at 1250°C for 10h. The SFT5 material is chemically compatible with the Ce0.8Sm0.2O1.9 (SDC) electrolyte at 1050°C for 2h. The highest electrical conductivity of 80Scm−1 at 650°C in air is obtained from the SFT5 sample. The thermal expansion coefficient (TEC) decreases with an increase in the SDC contents in SFT5 cathode, from 25.9×10−6K−1 at SFT5 to 17.2×10−6K−1 at SFT5–SDC30 between 30 and 1000°C in air. Single cells that use SFT5 with 0, 10, 20, and 30wt% SDC composite as cathodes on a 300μm-thick SDC electrolyte reach the peak power density of 360, 466, 513, and 425mWcm−2 at 800°C, respectively. The addition of SDC in SFT5 cathode significantly enhances the cell performance and reduces the TEC of the SFT5–SDC composite cathodes. The Ti-substituted SFT5 perovskites and SFT5–SDC composites can be considered cheaper alternative cathode materials for use in IT-SOFCs.