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

Abstract

Dense electrolyte supported micro tubular solid oxide fuel cells (T-SOFCs) were prepared in this study. Green Zr0.8Sc0.2O2 - delta (ScSZ) electrolyte micro-tubes with a thickness of 300 mu m were successfully prepared by extrusion at room temperature. After firing at 1400 degrees C, the bare electrolyte micro-tube with a thickness of 210 mu m, 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 degrees C, coated with NiO/ScSZ (60 vol.%:40 vol.%) in the inner surface of the microtubes by dip-coating method, and then co-fired at 1400 degrees 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 - delta (LSM)/Ce0.8Gd0.2O2 - delta (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 degrees C. The thicknesses of the anode and cathode layers read approximately 28 and 34 mu m respectively. After thermal cycling between 30 degrees C and 800 C under 97% N-2-3%H-2 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 degrees C, and the open circuit voltage (OCV) reported the same 1.08 V. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.