Novel Engineered Nanostructured Complex Oxide for High Temperature Thermoelectric Power Generation

Abstract

Thermoelectric power generators are a promising technology that can produce electrical power directly from waste heat emitted in energy production and consumption systems. The essential component of thermoelectric generators is the thermoelectric material which performs the energy conversion process. In order to make thermoelectric devices to be considered a significant contributor to US energy infrastructure, it is essential first to foster improvements in high performance thermoelectric materials. They must possess not only a high conversion efficiency, but also need be composed of nontoxic and abundantly available elemental materials having high chemical stability in air up to 800-1000 K. In comparison with the conventional thermoelectric materials (intermetallic compounds); the layered oxide materials, such as the newly developed nontoxic p-type Ca3Co4O9, are particularly promising for thermoelectric applications because of their high stability at high temperatures in air. In recent years, the layered cobalt oxide Ca3Co4O9 system has gained great attention due to its outstanding thermoelectric performance (ZT=0.83 at 973 K) for the single crystal. Single crystals, however, are too small and expensive for practical applications. The current challenge for developing oxide thermoelectric materials is to improve the conversion efficiency of the polycrystalline Ca3Co4O9 ceramic, which is currently lower than that of the conventional thermoelectric materials. The distinctive objective in this research is to optimize the energy inter-conversion properties of p-type Ca3Co4O9 ceramic, through nano-structure engineering approaches. Novel methods of introducing the appropriate dopants and other nano-structures into the oxide were investigated, and the effect of dopants and nano-structure engineering on the thermoelectric performance of the Ca3Co4O9 system was evaluated. The above study will be instrumental for fabricating polycrystalline Ca3Co4O9 with optimized microstructure and enhanced thermoelectric properties.