Development of Skutterudite Thermoelectric Materials and Modules

Multifilling with La, Ba, Ga, and Ti in p-type skutterudite and Yb, Ca, Al, Ga, and In in n-type skutterudite remarkably reduces their thermal conductivity, resulting in enhancement of their dimensionless figure of merit ZT to ZT = 0.75 for p-type (La,Ba,Ga,Ti)1(Fe,Co)4Sb12 and ZT = 1.0 for n-type (Yb,Ca,Al,Ga,In)0.7(Co,Fe)4Sb12. A thermoelectric module technology suitable for these skutterudites including diffusion barrier and electrode materials has been established. The diffusion barrier materials allow the electrode to coexist stably with the p/n skutterudites in the module’s working temperature range of room temperature to 600°C. Under conditions of hot/cold-side temperatures of 600°C/50°C, a skutterudite module with size of 50 mm × 50 mm × 7.6 mm exhibited generation performance of 32 W power output and 8% thermoelectric conversion efficiency.