Acceptor-doped La1.9M0.1Ce2O7 (M = Nd, Sm, Dy, Y, In) proton ceramics and in-situ formed electron-blocking layer for solid oxide fuel cells applications

Abstract

In the present work, La1.9M0.1Ce2O7 (M = Nd, Sm, Dy, Y, In) powders are synthesized by citric acid-nitrate sol-gel combustion method. The effects of the acceptor dopant on the phase structure, microstructure and electrical properties of La1.9M0.1Ce2O7 ceramics are investigated. All La1.9M0.1Ce2O7 ceramics possess a single-phase fluorite structure. It turns out that the In-doped ceramic exhibits the highest electrical conductivity of 0.82 × 10−2 and 2.03 × 10−2 S cm−1 at 700 °C both in dry air and wet 5% H2Ar atmospheres, respectively. Furthermore, in order to eliminate the internal short circuit resulting from the reduction of Ce4+ to Ce3+, a novel NiBaCe0.5Zr0.3Dy0.2O3-δ composite is applied and evaluated as the anode for the fuel cell based on La1.9In0.1Ce2O7 electrolyte. Raman and scanning electron microscope and energy dispersive spectrometer analyses indicate that a Ba-containing electron-blocking layer is formed in-situ at the anode/electrolyte interface. The new structured fuel cell with NiBaCe0.5Zr0.3Dy0.2O3-δ anode and La1.9In0.1Ce2O7 electrolyte exhibit significantly improved open circuit voltage of 1.005 V along with maximum power density of 546 mW cm−2 at 700 °C using humidified hydrogen fuel. The results demonstrate that La1.9In0.1Ce2O7 electrolyte and NiBaCe0.5Zr0.3Dy0.2O3-δ anode can be considered as the promising candidates for solid oxide fuel cells applications.