Effect of porous YSZ scaffold microstructure on the long-term performance of infiltrated Ni-YSZ anodes

Ni infiltration into porous YSZ scaffolds is a promising route for the construction of high performing and redox-stable Ni-YSZ anodes for application in solid oxide fuel cells (SOFCs). However, the long-term instability of this type of anode is a critical problem. Here, it is shown that an interconnected Ni film, rather than discrete Ni particles, can be formed inside a porous, pre-sintered YSZ scaffold by using a polymeric Ni-based precursor as the infiltration medium. To understand the effect of the YSZ microstructure on the long-term stability and the electrochemical performance of the resulting composites, two types of Ni-YSZ anodes were investigated. Anodes prepared by polymeric Ni infiltration into a YSZ Scaffold with large grains (0.5 mu m) and pores (0.5 mu m and 5 mu m) showed extensive agglomeration in the Ni phase, resulting in poor stability and poor activity. In contrast, Ni infiltration into YSZ scaffolds with finer particle and pore sizes (similar to 200 nm each) produced anodes with a very small polarization resistance of ca. 0.1 Omega cm(2) per electrode at 800 degrees C. An increase of only similar to 5% was seen in the resistance after ca. 110 h at this temperature, achieved by preventing Ni agglomeration. (C) 2015 Elsevier B.V. All rights reserved.