Porous YSZ impregnated with La_(0.4)Sr_(0.5)Ba_(0.1)TiO_3 as a possible composite anode for SOFCs fueled with sour feeds

摘要

The system LSBT/YSZ (LSBT is La_(0.4)Sr_(0.5)Ba_(0.1)TiO_3) is a promising combination as an anode material for full ceramic SOFCs. An anode comprising a porous layer of YSZ impregnated with LSBT shows good performance for conversion of high sulfur content fuels. The microstructurcs within the composite matrix were determined and correlated with the parameters of the production process. The anodes were characterized electrochemically using impedance spectroscopy (F.1S) and potentiodynamic tests performed at 850 C with various fuels to determine the effect of H_2S in the feeds: H_2, H_2/H_2S (5000 ppml, CH_4, CH4/H2S (5000 ppm). The highest power densities (200 mW cm~(-2) in H_2/H_2S) were obtained for LSBT/YSZ composites after impregnation six times with LSBT, corresponding to 12.6 wt% LSBT; further impregnations dramatically decreased performance as a result of restricted access of fuel to active sites.