SrCo_(0.7)Fe_(0.2)Ta_(0.1)O_(3-δ) perovskite as a cathode material for intermediate-temperature solid oxide fuel cells

摘要

Perovskite oxide SrCo_(0.7)Fe_(0.2)Ta_(0.1)O_(3_δ) (SCFT) was synthesized by a solid-state reaction and investigated as a potential cathode material for intermediate-temperature solid oxide fuel cell (IT-SOFC). The single phase SCFT having a cubic perovskite structure was obtained by sintering the sample at 1200 ℃ for 10 h in air. Introduction of Ta improved the phase stability of SCFT. The SCFT exhibited a good chemical compatibility with the La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3-δ) (LSGM) electrolyte at 950 ℃ for 10 h. The average thermal expansion coefficient was 23.8 × 10~(-6) K~(-1) between 30 and 1000 ℃ in air. The electrical conductivities of the SCFT sample were 71-119 S cm~(-1) in the 600-800 ℃ temperature range in air, and the maximum conductivity reached 247 S cm~(-1) at 325 ℃. The polarization resistance of the SCFT cathode on the LSGM electrolyte was 0.159 Ω cm~2 at 700 ℃. The maximum power density of a single-cell with the SCFT cathode on a 300 μm-thick LSGM electrolyte reached 652.9 mW cm~(-2) at 800 ℃. The SCFT cathode had shown a good electrochemical stability over a period of 20 h short-term testing. These findings indicated that the SCFT could be a suitable alternative cathode material for IT-SOFCs.