Solution combustion-based synthesis of NiO-GDC and NiO-SDC nanocomposites for low-temperature SOFC

In the last decades, NiO-GDC and NiO-SDC composites have emerged as interesting anodic materials for low and intermediate-temperature Solid Oxide Fuel Cells (SOFC) due to their high electrical conductivities and low activation energies. In this work, we report a simple and efficient Solution Combustion Synthesis (SCS) procedure for fabricating NiO-GDC and NiO-SDC nanocomposites with attractive physical properties for applications in low-temperature SOFC. The nitrate-fuel combustion method using citric acid as organic fuel was chosen due to its relatively low cost and good efficiency. Their potential electrical and mechanical performance for competitive SOFC anode technologies was assessed by characterizing disk-like compacted powders obtained by SCS. Two structurally optimized NiO-GDC and NiO-SDC disks were considered for the study of these properties, which presented good porosity and compaction degree. Vickers hardness tests show the good mechanical properties of both samples, achieving maximum hardness values of 4.7–6.7 [GPa] and validating the efficiency of the used compaction process. Electrical conductivity studies suggest an insulating-like behavior for both samples, evidenced by an increase in conductivity as the temperature increases. Good conductivities and low activation energies about of 10⁻² [S/cm] and 0.18 [eV] were estimated for a low-temperature operation regime (400–600 °C), respectively, representing a highly competitive performance concerning similar composites typically reported in the literature. Results show the efficiency of our fabrication procedures to produce efficient and competitive NiO-GDC and NiO-SDC composites with projections for future large-scale manufacturing of low-temperature SOFC anodes.