Direct foamed and nanocatalyst impregnated SOFC cathodes

Abstract

A binder system containing polyurethane precursors was used to in situ foam (direct foam) an (La 0.6 Sr 0.4 ) 0.98 (Co 0.2 Fe 0.8 )O 3−δ (LSCF) cathode composition on an yttrium-stabilised zirconia (YSZ) electrolyte coated with a porous ∼10 µm thick cathode active layer. The YSZ electrolyte was ∼110 μm thick, and a fuel cell was created by application of a Ni/(Ce 0.9 Gd 0.1 )O 2 cermet as the baseline anode. Cells possessing the foamed LSCF cathode were compared to cells constructed via standard methods in terms of resultant microstructure, electrochemical performance, and introceptive character. The foamed cathode tended to possess a high level of tortuous porosity which was ellipsoidal and interconnected in character. Both the standard and foamed cathode structures were subjected to an infiltration process, and the resultant microstructure was examined. The impregnation efficiency of the foamed cathode was at least ∼10% greater per deposition than that of an unfoamed porous LSCF cathode. The SOFC with the Pt nanocatalyst impregnated foamed cathode demonstrated a maximum power density of 593 mW/cm 2 utilising wet H 2 fuel, which is 52% higher than an SOFC with the baseline Pt-impregnated LSCF cathode (∼390 mW/cm 2 ) at 800°C. The cathode compositional and microstructural alterations obtainable by foaming led to the elevated power performance, which was shown to be quite high relative to standard SOFCs with a thick YSZ electrolyte.