Layered perovskites as promising cathodes for intermediate temperature solid oxide fuel cells

The suitability of GdBaCo2O5+delta as a cathode material for intermediate temperature solid oxide fuel cells has been evaluated. The O-18/O-16 isotope exchange depth profile (IEDP) method has been used to obtain the oxygen surface exchange and oxygen tracer diffusion coefficients yielding optimum values for applicability in fuel cells (k* = 2.8 x 10(-7) cm s(-1) and D* = 4.8 x 10(-10) cm(2) s(-1) at 575 degrees C) especially in terms of low activation energies (E-A(k) = 0.81(4) and E-A(D) = 0.60(4)eV). The same material has been characterized electrically as a part of a symmetrical electrochemical system (GdBaCo2O5+delta/Ce0.9Gd0.1O2-x/GdBaCo2O5+delta), by means of impedance spectroscopy measurements, corroborating an excellent performance in the classical intermediate temperature range for solid oxide fuel cells (500-700 degrees C). An area specific resistance (electrode electrolyte interface) of 0.25 Omega cm(2) at 625 degrees C was achieved for a cell processing temperature of 975 degrees C. Finally, layered perovskites are presented as a promising new family of materials for cathode use in solid oxide fuel cells at low temperatures.