Ionic Conduction And Their Performance Of SOFC Based On Ba_xCe_0.8RE_0.2O_3-α

Two series of BaxCe0.8Gd0.2O3-α and BaxCe0.8Dy0.2O3-α (x = 0.98, 1, 1.03) were prepared by high-temperature solid reaction. As a comparison, Ba1.03Ce0.8Gd0.2O3-α was synthesized by sol-gel method. Among these samples, nonstoichiometric samples were synthesized for the first time. The research work involved: the crystal phase of the sinters were determined by XRD; ionic conduction under different experimental atmospheres was measured by gas concentration cells; performances of hydrogen-air fuel cells with the sinters as electrolytes and porous Pt as electrodes were measured. The results showed: all of the ceramic sinters were a single phase of orthorhombic perovskite of BaCeO3; the two series of ceramics were excellent prolonic conductors under wet hydrogen atmosphere, and BaxCe0.8Dy0.2O3-α series were almost pure protonic conductors; whereas two series were the mixed electron-hole and oxide-ion conductors under dry air or oxygen gas; the hydrogen - air fuel cells constructed by them had stable discharging performances. As a whole, the electric performance of BaxCe0.8Dy0.2O3-α series is much better than BaxCe0.8Gd0.2O3-α series; Ba1.03Ce0.8Gd0.2O3-α prepared by sol-gel method had lower protonic transport number, whereas it had higher oxide-ion transport number and better fuel-cell performance than the sample prepared by traditional high temperature solid-state reaction. In the case of SOFC performance, BaCe0.8Gd0.2O3-α exhibitedmaximum short-circuit density and power density of 340 mA-cm-2 and 84 mW-cm-2 ,respectively.