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

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 − γ electrolyte. The thermal expansion coefficient was found to be approximately 11.8 × 10− 6 K− 1 from 100 °C to 800 °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 − γ anode-supported button cells fabricated with a Ce0.9Gd0.1O2 − γ electrolyte and Bi1.78Ca2Co1.63O6.65 cathode reached 551.2 mW · cm− 2 at 704 °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 Bi1.78Ca2Co1.63O6.65 as a potential novel cathode material for intermediate temperature-solid oxide fuel cells.