Enhancement of electrochemical performance and thermal compatibility of GdBaCo2/3Fe2/3Cu2/3O5+delta cathode on Ce1.9Gd0.1O1.95 electrolyte for IT-SOFCs

Abstract

Transition-metal doped double-perovskite structure oxides GdBaCo2/3Fe2/3Ni2/3O5+delta (FN-GBCO), GdBaCo2/3 Fe2/3Cu2/3O5+delta (FC-GBCO), GdBaCoCuO5+delta (C-GBCO) and pristine GdBaCo2O5+delta (GBCO) were synthesized via a citrate combustion method. The thermal-expansion coefficient (TEC) and electrochemical performance of the oxides were investigated as potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The TEC exhibited by the FC-GBCO cathode up to 900 degrees C is 14.6 x 10(-6) degrees C-1, which is lower than the value of GBCO (19.9 x 10(-6) degrees C-1). Area specific resistances (ASR) of 0.165 Omega cm(2) at 700 degrees C and 0.048 Omega cm(2) at 750 degrees C were achieved for the FC-GBCO cathode on a Ce0.9Gd0.1O1.95 (CGO) electrolyte. An electrolyte supported (300 mu m thick) single-cell configuration of FC-GBCO/CGO/Ni-CGO attained a maximum power density of 435 MW cm(-2) at 700 degrees C. The unique composition of GBCO co-doped with Fe and Cu ions in the Co, sites exhibited reduced TEC and enhancement of electrochemical performance and good chemical compatibility with CGO, and this composition is proving to be a potential cathode for IT-SOFCs. (C) 2009 Elsevier B.V. All rights reserved.