Optimum cathode configuration for IT-SOFC using La0.4Ba0.6CoO3−δ and Ce0.9Gd0.1O1.95

Abstract

Three different cathode configurations using porous layers of La0.4Ba0.6CoO3-d (LBC), LBCGDC composite in a 1:1 weight ratio, and GDC were prepared and tested by impedance spectroscopy measurements on symmetrical cells. The sequence of layers for the three cathode configurations is: A)porous GDC + LBC, B) porous GDC + LBCGDC composite, C) porous GDC + LBCGDC composite + LBC. The minimum polarization resistance (Rp) value was obtained with configuration C. The incorporation of both the porous GDC layer and the intermediate layer of LBC-GDC composite, allowed us to solve adherence problems caused by the total expansion mismatch between LBC (26 10-6 K-1) and GDC (12 10-6 K-1). The Rp values obtained with cell C are comparable to the performance of another cell C prepared with Ba0.5Sr0.5Co0.8Fe0.2O3-d (BSCF). For example, the Rp values at 600 ºC, in air, were 0.071 and 0.065 Ωcm2 for LBC and BSCF, respectively. These results suggest that configuration C is very promising for developing IT-SOFC cathode with low Rp values.