Enhanced Activity of Pr <sub>6</sub> O <sub>11</sub> and CuO Infiltrated Ce <sub>0.9</sub> Gd <sub>0.1</sub> O <sub>2</sub> Based Composite Oxygen Electrodes
Mohamad Khoshkalam, M.A. Faghihi-Sani, Xiaofeng Tong, Ming Chen, Peter Vang Hendriksen
Abstract
Operation of solid oxide fuel/electrolysis cells (SOFC/SOEC) at high temperatures (T > 850 °C) is accompanied by degradation phenomena, which severely affect the operational lifetime of the cell. Degradation processes are expected to occur slower at low temperatures. However, significant reduction in electrocatalytic activity of the oxygen electrode, is one of the major challenges in decreasing the operating temperature down to 500 °C–650 °C. Recently, Pr 6 O 11 infiltrated Ce 0.9 Gd 0.1 O 2 (CGO) based electrodes have been proposed to realize high electrochemical performance at intermediate temperature. In this study, Pr-oxide has been infiltrated into a well performing sub-micro La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 /Ce 0.9 Gd 0.1 O 2 (LSCF/CGO) composite electrode as well as a poorly performing LaNi 0.6 Fe 0.4 O 3 /Ce 0.9 Gd 0.1 O 2 (LNF/CGO) electrode. The results are compared with Cu-oxide infiltration. Formation of Pr rich oxide surface nanostructures, resulted in a pronounced reduction of polarization resistances by a factor of 3 in state of the art LSCF/CGO electrodes. Even better performances were achieved in Pr 6 O 11 infiltrated LNF/CGO, demonstrating low polarization resistances of 0.074 ∓ 0.002 and 0.146 ∓ 0.002 Ω.cm 2 at 600 °C and 550 °C, respectively. Low degradation rates were observed over a 200 h durability test at 650 °C, illustrating the potential of Pr 6 O 11 infiltrated CGO oxygen electrodes for intermediate temperature SOFC/SOEC application.