Construction and scale-up of high performing SOFC with enhanced GdxCe1-xO2-δ barrier layer self-crystallization and defect-free GDC-YSZ interface

The dense GDC (GdxCe1-xO2-s) barrier layer effectively prevents interactions between Zirconia based electrolytes and many high-performance cathodes. Previously, we reported the one-step in-situ hydrothermal selfcrystallization method to fabricate ultrathin and dense GDC barrier layer, directly in Nitrate solutions. However, this technique encounters the critical issues of slow GDC film growth rate and low Gd doping. Herin, we propose Urea as acidity regulator and evaluate the effect of urea addition on GDC self-crystallization. The results are encouraging, i.e., the GDC film exhibits a doubled growth rate of 220 nm/10 hand a fivefold increase in Gd doping up to 15 %, compared with the control sample. Moreover, the milder solution acidity yields improvement of GDC-YSZ (Y0.16Zr0.84O2-s) interface, presumably by suppressing the acid etching of YSZ surface. This optimized bilayer electrolyte enables enhanced anode supported SOFC performance, with smaller ohmic resistance of 0.087 Omega cm2 and higher peak power density of 0.808 W/cm2 at 750 degrees C. Furthermore, we successfully demonstrate the scale-up fabrication of large-size SOFC with cathode area of 100 cm2, which performs about 75 W at 0.7 V and 720 degrees C. This work promotes the industrial application feasibility of in-situ hydrothermal growth method for convenient and controlled GdxCe1-xO2-s barrier layer fabrication.