Solid Oxide Fuel Cells
Solid oxide fuel cells are high temperature (typically several hundred to about 1000 C) electrochemical devices that convert fuel to electricity through an oxide-ion conducting ceramic electrolyte. Their efficiency is often limited by oxygen reduction at the cathode, commonly a perovskite such as Sr-doped LaMnO3, so cathode composition, microstructure and the density of active sites near phase boundaries are central design variables.
Infiltrating SOFC cathodes with EISA solutions (2011)
Chao, Kitchin, Gerdes, Sabolsky and Salvador used an evaporation-induced self-assembly (EISA) solution of La, Sr and Mn nitrates with the surfactant CTAB as a wet-impregnation vehicle for porous cathodes (Chao et al. 2011). A single 10 uL infiltration, drawn in by capillarity and calcined at 800 C, placed La0.8Sr0.2MnO3 nanoparticles through the full thickness of porous YSZ pellets, LSM cathodes on samaria-doped ceria, and the LSCF cathode of a commercial anode-supported button cell, at 0.5 to 1.2 wt% per step, with the same non-optimized solution wetting all three backbones. After five cycles (about 6 wt%) in the LSCF cell, the LSM concentrated within about 10 to 20 um of the electrolyte, in the functional layer, as thin coatings that did not visibly clog submicron pores. The authors argue this could put catalyst where it is most effective while leaving the current collector open for gas flow; no electrochemical data were reported. Summary: chao2011.
High surface area infiltration catalysts for SOFC cathodes (2012)
Motivated by cathode overpotentials from slow oxygen reduction, Chao and co-workers developed mesoporous La0.8Sr0.2MnO3 powders by evaporation-induced self-assembly, a solution route compatible with infiltrating nanoscale catalyst onto cathode pore walls. The powders reached up to 46 m2/g, and those templated with the large surfactants P-123 and F-127 lost only 11% and 6% of their surface area after 100 h at 750 C, an intermediate SOFC operating temperature. The authors note that stability on real cathode supports and under electrochemical load remains to be tested (Chao et al. 2012). Summary: chao2012.