Efficient strategy to boost the electrochemical performance of yttrium stabilized zirconia electrolyte solid oxide fuel cell for low-temperature applications

Abstract

Yttrium stabilized zirconia (YSZ) used as the state-of-the-art electrolyte for solid oxide fuel cells (SOFCs) requires high temperature (over 800 °C) to realize sufficient oxygen ion conductivity. Thus, the high operational temperature is the main restriction for the commercial process of YSZ-based SOFCs. To obtain decent ionic conductivity at intermediate-low temperatures, Sr-free cathode LaNiO3 is introduced into YSZ to construct a novel LaNiO3-YSZ composite electrolyte, which is sandwiched by two Ni0.8Co0.15Al0.05LiO2-δ (NCAL) electrodes to assemble systematical fuel cells. This device presents an excellent peak output of 1045 mW cm-2 at 600 °C and even 399 mW cm-2 at 450 °C. A series of characterizations indicates that the oxygen ion conductivity of the LaNiO3-YSZ composite is significantly promoted in comparison with that of pure YSZ, and the LaNiO3 component has certain proton conductivity after hydrogenation. Both of the two factors contributes to the superior performance of such devices at intermediate-low temperatures. Furthermore, the sharp decrease in electronic conductivity for LaNiO3 in hydrogen atmosphere combined with Schottky junction at the anode-electrolyte interface eliminates the short-circuiting problem. Our work demonstrates that incorporating Sr-free cathode LaNiO3 into the YSZ electrolyte is an efficient strategy to boost the performance and reduce the operational temperature of YSZ-based SOFCs.