Calcium doped Y3Fe5O12 as a new cathode material for intermediate temperature solid oxide fuel cells

Abstract Calcium doped yttrium iron garnet, Y2.5Ca0.5Fe5O12−δ (YCFO), was studied as a new cathode material for intermediate temperature solid oxide fuel cells. Low polarization resistance of 0.55 Ωcm2 at 650 °C was realized with the use of YCFO–Ce0.8Sm0.2O1.9 (SDC, 40 wt.%) composite electrode. An investigation over limiting steps of the cathode reaction suggests that oxygen ion diffusion, oxygen dissociative adsorption, and gas-phase diffusion might be the rate-limiting steps for the YCFO–SDC cathode. Of a single cell using the YCFO–SDC composite cathode, the polarization resistance reduces to as low as 0.14 Ωcm2 measured at 650 °C, and the maximum power density reaches 438 mW cm−2 with a 40 μm – thick SDC electrolyte.