Fabrication of electrolyte supported micro-tubular SOFCs using extrusion and dip-coating

Dense electrolyte supported micro tubular solid oxide fuel cells (T-SOFCs) were prepared in this study. Green Zr0.8Sc0.2O2 − δ (ScSZ) electrolyte micro-tubes with a thickness of 300 μm were successfully prepared by extrusion at room temperature. After firing at 1400 °C, the bare electrolyte micro-tube with a thickness of 210 μm, a diameter of 3.8 mm, and a length of 40 mm reached a relative density of 96.84% and a flexural strength of 202 MPa. To achieve a better sintering shrinkage match, the electrolyte micro-tubes were pre-sintered at 1100 °C, coated with NiO/ScSZ (60 vol.%:40 vol.%) in the inner surface of the micro-tubes by dip-coating method, and then co-fired at 1400 °C. After co-sintering, the interface of the porous anode layer and the dense electrolyte layer demonstrated good adhesion and mechanical integrity. Subsequently, a La0.8Sr0.2MnO3 − δ (LSM)/Ce0.8Gd0.2O2 − δ (GDC) (80 vol.%:20 vol.%) cathode layer was coated on the outer surface of the micro-tubes by dip-coating method and post-sintered at 1100 °C. The thicknesses of the anode and cathode layers read approximately 28 and 34 μm respectively. After thermal cycling between 30 °C and 800 °C under 97% N2–3%H2 on the anode and air on the cathode, the micro T-SOFCs showed no delamination and retained good adhesion based on the SEM results. The maximum power densities (MPD) of the single cell read 0.26 and 0.23 W cm−2 respectively at 920 and 900 °C, and the open circuit voltage (OCV) reported the same 1.08 V.

► Electrolyte supported micro tubular solid oxide fuel cells were prepared. ► Dense tubes read a relative density of 97.1% and a bending strength of 190 MPa. ► Micro T-SOFCs showed no delamination and retained good adhesion.