Nanoscale Analysis of LSM/YSZ Interfaces within Composite Cathodes for Commercial Solid Oxide Fuel Cells

Abstract

Atom probe tomography (APT) was utilized to probe composition at the nanoscale across cathode/electrolyte interfaces for anode-supported commercial SOFCs. These SOFCs contained a porous composite cathode layer, consisting of sintered (La0.8Sr0.2)0.95MnO3 (LSM) and yttria-stabilized zirconia (YSZ). SOFCs were operated up to a 500 h duration at a 0.75 A/cm2 current density and 800°C. The measured cell voltage increased over the first 100 hours of operation, followed by a steady and linear drop in cell voltage that translated to a 5.35% performance loss per 1000 h. Cation migration behavior was extrapolated through comparisons of compositional profiles acquired by APT across LSM/YSZ particle interfaces for as-sintered, operated, and thermally aged conditions. The results show that operation drives La/Sr away from the LSM nanoparticle surface and Y depletion at the YSZ nanoparticle surface. Energy dispersive spectroscopy (EDS) inside a scanning transmission electron microscope (STEM) provided additional insights regarding Mn aggregation behavior during operation.