High-performance electrodes for reduced temperature solid oxide fuel cellswith doped lanthanum gallate electrolyte II. La(Sr)CoO3 cathode

The reduced temperature solid oxide fuel cell (SOFC) with 0.5 mm thick La0. 9Sr0.1Ga0.8Mg0.2O3-alpha (LSGM) electrolyte, La0.6Sr0.4CoO3-delta (LSCo) ca thode, and Ni-(CeO2)(0.8)(SmO1.5)(0.2) (SDC) cermet anode showed an excelle nt initial performance, and high maximum power density, 0.47 W/cm(2), at 80 0 degrees C. The results were comparable to those for the conventional SOFC with yttria-stabilized zirconia (YSZ) electrolyte, La(Sr)MnO3-YSZ cathode and Ni-YSZ cermet anode at 1000 degrees C. Using an LSCo powder prepared by spray pyrolysis, and selecting appropriate sintering temperatures, the low est cathodic polarization of about 25 mV at 300 mA/cm(2) was measured for a cathode prepared by sintering at 1000 degrees C. Life time cell test resul ts, however, showed that the polarization of the LSCo cathode increased wit h operating time. From EPMA results, this behavior was considered to be rel ated to the interdiffusion of the elements at the cathode/electrolyte inter face. Calcination of LSCo powder could be a possible way to suppress this i nterdiffusion at the interface. (C) 2000 Elsevier Science S.A. All rights r eserved.