La0.6Sr0.4Co0.2Fe0.8O3−δ–SDC carbonate composite cathodes for low-temperature solid oxide fuel cells

Composite cathodes with La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF6428) and samarium-doped ceria carbonate (SDCC) were developed and investigated for solid oxide fuel cell (SOFC) applications at low operating temperatures. The LSCF–SDCC (50 wt% LSCF:50 wt% SDCC) composite cathode powders were mixed by the ball-milling technique followed by calcination at 700, 750, 800, and 850 °C for 2 h. To fabricate single SOFCs using LSCF–SDCC as the cathode, SDCC as the electrolyte, and NiO–SDCC as the anode, a single-step pressing and co-firing process was employed. The electrolyte-supported button cells were tested between 475 and 550 °C. The composite cathode exhibited well-matched TEC values with the SDCC electrolyte. Calcination at lower temperatures (700 and 750 °C) produced powders with surface areas of 10 m2 g−1–11 m2 g−1. Using LSCF–SDCC powders sintered at 700 and 750 °C to fabricate button cells resulted in power densities of 117.9 and 120.4 mW cm−2, respectively, at an operation temperature of 550 °C with the latter cathode yielding the lowest Rp value.