Impregnated LSM-YSZ electrodes with RuO2/SDC nanocomposites for solid oxide cells

Abstract

La0.8Sr0.2MnO3-δ-Y0.16Zr0.84O2-δ (LSM-YSZ) composites have been widely used as the oxygen electrodes in solid oxide cells (SOCs), however, their poor activities for oxygen reduction and evolution reactions result in relatively low cell performance. A common method to promote electrocatalytic activities of LSM-YSZ composites is to tailor the microstructure by impregnation. In this study, nanocomposite catalysts are developed by one-pot infiltration, where nano scale particles of RuO2 and Ce0.8Sm0.2O2-δ (SDC) are highly dispersed to achieve a uniform distribution with reduced particle sizes. Impedance measurements of symmetrical oxygen electrode cells reveal that modifying LSM-YSZ electrodes with SDC and RuO2/SDC can substantially promote their activities for oxygen reduction reactions (ORR). The measured polarization resistances at 750°C in air are 2.23, 0.24 and 0.14 Ω cm2 for the blank, SDC and RuO2/SDC modified LSM-YSZ electrodes, respectively. Compared to pure SDC, RuO2/SDC composites show higher ORR promotion, which can be correlated with their more surface oxygen vacancies. Solid oxide cells with thin YSZ electrolytes, RuO2/SDC impregnated LSM-YSZ oxygen electrode substrates and thin fuel electrodes of La0.3Sr1.55Fe1.5Ni0.1Mo0.4O6 achieve a peak power density of 0.7 W cm−2 at 750°C in the fuel cell mode and a steam electrolysis current density of 2.31 A cm−2 at 1.3 V and 800°C in the electrolysis mode.