Nanostructured Ni-YSZ by Atomic Layer Deposition

Abstract

Nickel yttria-stabilized zirconia (Ni-YSZ) is used as anode material for solid oxide fuel cells (SOFCs). The electrochemical performance of Ni-YSZ anodes can be improved when the size of constituent particles of nickel is reduced. However, at SOFC high temperature operating environments, nano-sized Ni particles suffer from sintering. Nanoscale Ni-YSZ anodes can undergo severe structure changes. In this work, a unique approach of fabricating a nanostructured Ni-YSZ anode is demonstrated by combining atomic layer deposition (ALD) and glancing angle deposition (GLAD) techniques whereby nickel nanoparticle sintering is prevented at high temperatures with as thin as 1.9 nm YSZ ALD coating on the nickel; the surface area of the resulting Ni-YSZ anode was found to increase more than 3 times that of a planar electrode. In addition, the novel ALD/GLAD coating approach used here provides an ionic conductive YSZ electrolyte phase combined with an electrical conductive Ni phase whereby porosity can be controlled through deposition and post-deposition annealing. In addition, the surface roughness of Ni-YSZ anode decreases with increasing YSZ coating layer thickness and it is unaffected by the post-deposition annealing process. Conductivity measurements of the Ni-YSZ anodes at room temperature show a resistivity in the order of 10−4 cm·S−1.