Novel layered perovskite GdBaCuFeO5+x as a potential cathode for proton-conducting solid oxide fuel cells

A layered perovskite GdBaCuFeO5+x (GBCuF) was developed as a cathode material for intermediate-temperature solid oxide fuel cells based on a proton-conducting electrolyte of stable BaZr0.1Ce0.7Y0.2O3-delta (BZCY). The X-ray diffraction results showed that GBCuF was chemically compatible with BZCY after co-fired at 1,000 A degrees C for 10 h. The thermal expansion coefficient of GBCuF, which showed a reasonably reduced value (15.1 x 10(-6) K-1), was much closer to that of BZCY than the cobalt-containing conductor. The button cells of Ni-BZCY/BZCY/GBCuF were fabricated and tested from 500 to 700 A degrees C with humidified H-2 (similar to 3 % H2O) as a fuel and ambient oxygen as the oxidant. A high open-circuit potential of 1.04 V, maximum power density of 414 mW cm(-2), and a low electrode polarization resistance of 0.21 Omega cm(2) were achieved at 700 A degrees C, with calculated activation energy (E (a)) of 128 kJ mol(-1) for the GBCuF cathode. The experimental results indicated that the layered perovskite GBCuF is a good candidate for cathode material.