Preparation and evaluation of novel Bi1.91Sr2Co1.96O7.08 cathode for intermediate temperature-solid oxide fuel cells

Abstract

Novel cathode material Bi1.91Sr2Co1.96O7.08 (BSCO) was synthesized by ethylene glycol assisted sol-gel method for intermediate temperature solid oxide fuel cells (IT-SOFCs). In addition to its good thermal stability, it shows chemical and thermal compatibility with Ce0.9Gd0.1O2−γ electrolyte. Thermal expansion coefficient of BSCO is found to be approximately 11.2 × 10−6 K−1 from 100 °C to 800 °C, which is the main merit of this material compared with other cobaltite based perovskite cathodes. Electrical conductivity of BSCO is about 8–9 S cm−1 between 600 and 700 °C, and polarization resistance of BSCO cathode on Ce0.9Gd0.1O2−γ electrolyte are 0.1, 0.3 and 1.3 Ω·cm2 at 800, 748 and 695 °C, respectively. Maximum power density based on BSCO/GDC/NiO-GDC cell is 495 mW·cm−2 at 700 oC. Given that the thermal compatibility with the electrolyte and the encouraging electrochemical performance, BSCO could be considered as an alternative cathode material for IT-SOFCs.