Advanced Cathodes for Solid Oxide Fuel Cells
As highly efficient energy conversion devices with negligible impact on environment, solid oxide fuel cells (SOFCs) have received considerable attention recently as a keystone of the future energy economy. Current developments in SOFCs focus on increasing the durability and lowering the cost of the system and the materials therein. It is generally recognized that these goals can be realized by lowering the SOFC operating temperature to the low- to intermediate-temperature (LIT) region (500-750°C). The main barrier to achieving acceptable chemical to electrical conversion efficiency in LIT-SOFCs is the sluggish oxygen reduction reaction (ORR) kinetics of the cathode. In this chapter, we review the electrochemical performance of cathodes with different crystal structures, that is, perovskite, double perovskite, and K2NiF4. We focus on the application of these cathodes on oxide ion- and proton-conducting electrolytes. In addition, we introduce some advanced techniques for cathode fabrication (wet impregnation, surfactant-assisted assembly, and spray pyrolysis).