Introduction of Multiple CeO2 Interlayers to Avoid Ni Agglomeration in Nanoscale Ni-YSZ Solid Oxide Cell Hydrogen Electrodes

Abstract

Nanostructuring of solid oxide cell (SOC) electrodes is necessary for enhancing the electrochemically active triple phase boundary length and thus lowering the operating temperature of these devices. However, nanoscale morphology in nickel-yttria-stabilized zirconia (Ni-YSZ) electrodes renders the structure extremely prone to Ni agglomeration and hence performance degradation upon long-term operation. To overcome this challenge, application of multiple CeO2 nanolayers into the nanoscale Ni-YSZ electrodes, all produced from direct deposition of liquid precursors, is proposed. This way, constraining the movement of Ni, while maintaining electronic and ionic transport within the electrodes, is aimed. Microscopy analyses reveal relatively stable microstructures in the case of electrodes with an optimized number of CeO2 interlayers after ca. 100 h exposure to dilute hydrogen flow at 650 degrees C. Meanwhile, severe Ni agglomeration is observed in reference nanoscale N-iYSZ electrodes. In accordance, the ca. 10(5)-fold increase in the electrode polarization resistance of bare Ni-YSZ under the same conditions is reduced to ca. 50% increase in the case of CeO2 interlayer containing electrodes. The results presented here provide an effective method to implement nanoscale Ni-YSZ electrodes in intermediate-temperature SOCs while retaining microstructural stability.