Bi1.78Ca2Co1.63O6.65 cathode with low thermal expansion coefficient for intermediate temperature-solid oxide fuel cells

Abstract

The misfit compound Bi1.78Ca2Co1.63O6.65 was successfully synthesized and evaluated as a novel cathode material for intermediate temperature solid oxide fuel cells exhibiting good thermal stability, as well as chemical and thermal compatibility with the Ce0.9Gd0.1O2 (-) (gamma) electrolyte. The thermal expansion coefficient was found to be approximately 11.8 x 10(-6) K-1 from 100 degrees C to 800 degrees C, which highlighted the main advantage of this material compared to other cobaltite based perovskite cathodes. The maximum power densities of the NiO/Ce0.9Gd0.1O2-gamma anode-supported button cells fabricated with a Ce0.9Gd0 O-1(2-gamma) electrolyte and Bi1.78Ca2Co1.63O6.65 cathode reached 5512 mW.cm(-2) at 704 degrees C with around 10% loss of activity during the 72 h test. The thermal compatibility with the electrolyte, along with the encouraging electrochemical performance, allows us to propose Bi1.28Ca2Co1.63O6.65 as a potential novel cathode material for intermediate temperature-solid oxide fuel cells. (C) 2013 Elsevier B.V. All rights reserved.