Effect of electrolyte thickness on the performance of anode-supported ceria cells

Abstract

Anode-supported ceria cells are promising as SOFCs (solid oxide fuel cells) to be used at intermediate temperatures. However, their performance varies widely depending on the experimental conditions due possibly to the partial electronic conductivity of the acceptor-doped ceria electrolyte that is observed in reducing atmosphere. In this study, the effect of electrolyte thickness on the performance of anode-supported ceria cells was studied. 20 mol% Gd-doped ceria (Gd0.2Ce0.8O2 - delta, GDC20) electrolyte films were coated on the porous Ni-GDC20 anode supports by screen printing and co-firing. BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3 - delta) was used for the cathode. The thickness of the GDC20 electrolyte was found to have a significant effect on the OCV (open circuit voltage), impedance spectra, I-V (current-voltage) and I-P (current-power) curves. When the thickness of the electrolyte decreased from 40 mu m to 12 mu m in the anode-supported cell, the maximum power densities (P-max) increased while the OCV values decreased. The OCV and Pmax values of the cell with 12 pm of GDC20 electrolyte were 0.772 V and 1.16 Wcm(-2), respectively, when 97% H-2 + 3% H2O was used as fuel and open air was used as the oxidant gas at 600 degrees C. Although a thin electrolyte layer reduces the OCV value, the reduced Ohmic and polarization resistance are advantageous for the cell performance in the tested thickness range because they increased the power density of cell. (C) 2010 Elsevier B.V. All rights reserved.