Performances of SmBaCoCuO5+δ–Ce0.9Gd0.1O1.95 composite cathodes for intermediate-temperature solid oxide fuel cells

SmBaCoCuO5+δ–xCe0.9Gd0.1O1.95 (SBCCO–xGDC, x = 10, 30, 50, 60, wt%) composite cathodes have been investigated for their potential utilization in intermediate temperature solid oxide fuel cells (IT-SOFCs). The thermal expansion behavior shows that the thermal expansion coefficient (TEC) values of SBCCO cathode decrease with GDC addition. The TEC of SBCCO–50GDC cathode is 13.1 × 10−6 K−1 from 30 to 850 °C in air. By means of DC polarization and AC impedance spectroscopy, the electrochemical performance of SBCCO–xGDC composite cathodes on GDC electrolyte is examined. Results indicate that the proper addition of GDC could improve the performance of SBCCO cathode. The optimum content of GDC in the composite cathodes is 50 wt% with the polarization resistance (Rp) of 0.040 Ω cm2 at 800 °C. An electrolyte-supported single-cell configuration of SBCCO–50GDC/GDC/Ni–GDC attains a maximum power density of 628 mW cm−2 at 800 °C. Preliminary results indicate that SBCCO–50GDC is especially promising as a cathode for IT-SOFCs.