Direct foamed and nano-catalyst impregnated solid-oxide fuel cell (SOFC) cathodes

Abstract

A binder system containing polyurethane precursors was used to in situ foam (direct foam) a (La0.6Sr0.4)0.98 (Co0.2 Fe0.8)O3−δ (LSCF) cathode composition upon a yttrium-stabilized zirconia (YSZ) electrolyte coated with a porous ∼10μm thick cathode active layer. The YSZ electrolyte was ∼110μm in thickness, and a full cell was created by application of a Ni/(Ce0.9Gd0.1)O2cermetas 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 nano-catalyst impregnated foamed cathode demonstrated a maximum power density of 593mW/cm2 utilizing wet H2 fuel, which is 52% higher than a SOFC with the baseline Pt-impregnated LSCF cathode (∼390mW/cm2) 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.