Boosting Low-Temperature Solid Oxide Fuel Cell Performance via Niobium and Indium Co-Doped SrCoO_3-δ Nanostructured...

In this study, Nb and In co-doped strontium cobaltite (SrCo_0.8Nb_0.1In_0.1O_3-δ, abbreviated as SCNI) perovskite was synthesized using both nonaqueous sol-gel (SCNI-SG) and solid-state (SCNI-SS) methods. The synthesized powders were calcined at various temperatures to achieve phase-pure perovskite structures and were subsequently used as cathodes in low-temperature solid oxide fuel cells. The SCNI-SG exhibited a morphology with particle sizes in the range of approximately 100-150 nm, whereas SCNI-SS showed particles in the micron scale, exceeding 5 μm. An electrolyte-based cell (Ni-gadolinia-doped ceria (GDC)/GDC/SCNI) was fabricated using an optimized GDC electrolyte. The symmetric cell with the SCNI-SG cathode exhibited a low area-specific resistance of 0.19 Ω·cm² at 600°C, which is promising for low-temperature applications. It also exhibited a maximum power density of 351 mW/cm² at 600°C, superior to the 304 mW/cm² achieved by the cell using SCNI-SS. This enhanced performance is attributed to the finer microstructure, smaller particle size with higher specific surface area, increased triple-phase boundary density, and synergistic interplay between high electronic conductivity ensuring efficient charge transport through the bulk, and surface oxygen vacancies promoting oxygen adsorption and activation steps during oxygen reduction reaction.