Effects of (LaSr)(CoFeCu)O3-δ cathodes on the characteristics of intermediate temperature solid oxide fuel cells

In this study, Cu2+ ions doped La0.6Sr0.4Co0.2Fe0.8O3-delta cathodes are prepared for use in solid oxide fuel cells (SOFCs). The maximum electrical conductivities of the La0.6Sr0.4Co0.2Fe0.7Cu0.1O3-delta (438S cm(-1)) and the La0.6Sr0.4Co0.1Fe0.8Cu0.1O3-delta (340 S cm(-1)) discs are higher than that of the La0.6Sr0.4Co0.2Fe0.8Cu0.1O3-delta disc (LSCF; 81S cm(-1)) sintered at 1100 degrees C. The substitution of Cu2+ over Fe3+ leads to a higher coefficients of thermal expansion (CTE), while the replacement of Co3+ by Cu2+ results in a lower CE. Single cells with the La0.6Sr0.4Co0.2Fe0.8O3-delta , La0.6Sr0.4Co0.2Cu0.1Fe0.7O3-delta, and La0.6Sr0.4Co0.1Fe0.8Cu0.1O3-delta cathodes operating at 650 degrees C and 550 degrees C show similar ohmic resistance (R-o) values while the polarization resistance (R-p) values of the cells with the La0.6Sr0.4Co0.2Fe0.7Cu0.1O3-delta and La0.6Sr0.4Co0.1Fe0.8Cu0.1O3-delta cathodes are slightly lower than that of the single cell with the La0.6Sr0.4Co0.2Fe0.8O3-delta cathode, indicating that the Cu2+-doped LSCF cathode exhibits a greater electrochemical catalytic activity for oxygen reduction. Maximum power densities of the cells with the La0.6Sr0.4Co0.2Fe0.8O3-delta , La0.6Sr0.4Co0.2Fe0.7O3-delta , and La0.6Sr0.4Co0.1Fe0.8Cu0.1O3-delta cathodes operating at 700 degrees C read respectively 1.07, 1.15, and 1.24 Wcm(-2). It is evident that the doping of Cu2+ ions in LSCF is beneficial to the electrochemical performance of the cells. (C) 2011 Elsevier B.V. All rights reserved.