Operational Inhomogeneities in La0.9Sr0.1Ga0.8Mg0.2O3 Electrolytes and La0.8Sr0.2Cr0.82Ru0.18O3Ce0.9Gd0.1O2 Composite Anodes for Solid Oxide Fuel Cells

Ni cermet anodes are commonly used in solid oxide fuel cells (SOFCs) [1–4], but there has been considerable interest in alternative oxide-based anodes [5]. The motivation for the alternative materials is to avoid problems with the Ni-based anodes, including susceptibility to coking in hydrocarbon and CO-rich fuels [6], poisoning by sulfur [7] and other fuel impurities [8], and degradation due to redox cycling [9]. A number of oxide materials have been identified that address these problems [10]. One recent example is La0.8Sr0.2Cr0.82Ru0.18O3–d (LSCrRu). This material has yielded good electrochemical performance that appears to be related to the formation of Ru nanoparticles on the chromite surfaces, although this has only been verified in powders, not in the anodes themselves [11]. One of the problems with oxide anode materials is their incompatibility with the electrolyte. For example, there are well-known problems with reactions between perovskite electrodes and yttrium-stabilized zirconia (YSZ) electrolytes that form resistive zirconate phases [12]. However, relatively little is known about the compatibility of oxide anodes with La0.9Sr0.1Ga0.8Mg0.2O3 (LSGM) electrolytes. A number of SOFCs with oxide anodes on LSGM-electrolyte supports have been reported [10, 11], and in some cases it was found that a La-doped ceria (LDC) interlayer was required to obtain good cell performance. The ceria interlayer presumably prevented deleterious anode/electrolyte interactions. However, little structural/chemical information is available for these material combinations [11]. Here we describe a transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and energy dispersive X-ray spectroscopy (EDX) study of