LaCoO3: Promising cathode material for protonic ceramic fuel cells based on a BaCe0.2Zr0.7Y0.1O3-delta electrolyte
Summary, in English
Symmetric cells (cathode/electrolyte/cathode) were prepared using BaCe0.2Zr0.7Y0.1O3-delta (BCZY27) as proton conducting electrolyte and LaCoO3 (LC) infiltrated into a porous BCZY27 backbone as cathode. Single phased LC was formed after annealing in air at 600 degrees C for 2 h. Scanning electron micrographs showed the presence of the infiltrated LC in the full cathode depth. Transmission electron micrographs revealed LC grains (60-80 nm) covering partly the BCZY27 grains (200 nm(-1) mu m). Impedance spectra were recorded at 500 degrees C and 600 degrees C, varying the oxygen partial pressure and the water vapour pressure. Two arcs correspond to the cathode contribution: a middle range frequency one (charge transfer) and a low frequency one (oxygen dissociation/adsorption). The area specific resistances (ASRs) of both contributions increase when decreasing the oxygen partial pressure. The low frequency arc is independent on the water vapour pressure while the charge transfer ASR values increase with higher pH(2)O. The cathode ASRs of 0.39 and 0.11 Omega cm(2) at 500 and 600 degrees C respectively, in air (pH(2)O = 0.01 atm) are the lowest reported to the authors' knowledge for PCFC cathodes. Furthermore, this work shows that the presence of oxide ion conduction in the cathode material is not necessary for good performance. (C) 2012 Elsevier B.V. All rights reserved.