Large footprint (144 cm 2 ) cells with infiltrated (La 0.6 Sr 0.4 ) 0.95 FeO 3 /yttria-stabilized zirconia (LSF-YSZ) cathodes were fabricated on a pre-production scale (approximately 90 cells/batch). The excellent electrochemical performance of the cells was confirmed both on single cell as well as on stack level. Changes in electrode properties were mapped out as a function of heat-treatment temperature. The microstructure of the porous zirconia backbone remained unchanged, but the surface area of the ferrite phase decreased gradually, as the electrode was treated to higher temperatures. Changes in surface area were accompanied by corresponding changes in pore size and total pore volume. In contrast to traditional composite electrodes, the in-plane conductivity of infiltrated LSF-YSZ cathodes decreased with increasing sintering temperature, a trend likely explained by microstructure alterations during the sintering of the non-random structure. Recently, the use of infiltration as a method for solid oxide fuel cell (SOFC) electrode preparation has gathered significant scientific interest.1-6 The infiltration (or impregnation) method resembles the wet impregnation and incipient wetness methods employed in heterogeneous catalysis. 7,8 The electrodes are prepared by the introduction of perovskite precursors (e.g. in the form of nanoparticles, aqueous nitrate solutions, or molten salts 9 ) into sintered porous backbone structures, typically made of electrolyte materials such as yttria-stabilized zirconia (YSZ) 1,9-12 or doped ceria. 3,6,13 Such electrodes have several advantages over traditional SOFC electrodes. Infiltration approach allows for the use of a wider range of active materials.1,2,10,12,14 Furthermore, infiltrated electrodes promise improved mechanical properties over traditional electrodes due to the lower thermal expansion mismatch between the electrolyte and cathode layers, 1,10 and enhanced performance due to the high surface area of the active phase. 1,6,12,16 Finally, the possibility of synthesizing the electrode active phase in situ within the electrolyte pores from relatively cheap nitrate precursors may offer significant materials cost advantages over traditional electrodes, where expensive perovskite powders with finely tuned particle size distributions are required for screen-printing. 17The results on infiltrated electrodes reported in the literature have so far been obtained almost exclusively on button cells with electrode active areas on the order of 1 cm 2 or less. A notable exception is the work by C. S. Ni et al., who have recently fabricated and tested 5 × 5 cm 2 cells where both the anode and the cathode was prepared by infiltration. 18 Here, we report the physical characterization and stack testing of 12 × 12 cm 2 planar cells with cathodes prepared by infiltration of a perovskite precursor solution into a stabilized zirconia (SZ) backbone. The results reported here were obtained primarily on infiltrated (La 0.6 Sr 0.4 ) 0.95 FeO 3 (LSF)-SZ electrodes. LSF-SZ is an excellent model sy...
A novel cell design consisting of a Ni/YSZ anode support, a Ni/YSZ anode, a zirconia-based electrolyte, and a porous stabilized zirconia backbone layer, infiltrated with a perovskite phase, is reported. The electrochemical performance of the large footprint (12 x 12 cm2) cells was tested both on single cell as well as stack level with promising results. The steady-state degradation rate of infiltrated cells in a stack was low (2.7 %/kh), despite the fact that changes in electrode microstructure and in-plane conductivity were observed, as the infiltrated cells were heat-treated to higher temperatures.
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