Synthesis and characterization of GdCoO3 as a potential SOFC cathode material

Gadolinium cobaltite (GdCoO3) powder has been synthesized by solution polymerization method and characterized for its application as cathode material in gadolinia doped ceria (GDC) electrolyte based intermediate temperature SOFC (IT-SOFC). Perovskite structured phase pure and nanocrystalline GdCoO3 powder was obtained after calcining the precursor at 800 °C. The powder was found to start sintering at about 850 °C on heating and could be sintered to near theoretical density at 1200 °C. The electrical conductivity of the sintered material was measured to be 580 S cm−1 at 800 °C and its coefficient of thermal expansion varied from 16 × 10−6 to 25 × 10−6 K−1 in the temperature range from 200 to 1000 °C. GdCoO3–GDC (1:1 wt.%) composite cathode was found to have coefficient of thermal expansion that match closely with GDC electrolyte. Symmetric cells were prepared using GDC electrolyte and GdCoO3–GDC composite as the electrode and the area specific resistance (ASR) for interfacial polarization was evaluated by AC impedance spectroscopic technique. ASR values of 1.1, 0.55 and 0.2 Ω cm2 have been obtained at 800, 850 and 900 °C, respectively.

► Nano GdCoO3 powder has been synthesized by solution polymerization method. ► GdCoO3–GDC composite electrode has been found to have coefficient of thermal expansion (CTE) matching with GDC electrolyte. ► Area specific resistance value of 0.2 Ω cm2 has been obtained at 900 °C.