High-Performance and Stable (Ag, Cd)-Containing ZnSb Thermoelectric Compounds.

Binary Zn-Sb-based compounds, ZnSb and Zn 4 Sb 3 , are promising thermoelectric (TE) materials because they are low-cost and earth-abundant. However, for a long time, their real applications have been limited by the low TE figure-of-merit ( zT ) of ZnSb and poor thermodynamic stability of Zn 4 Sb 3 . In this study, we successfully integrate both high zT and good stability in (Ag, Cd)-containing ZnSb compounds. Alloying Cd in ZnSb greatly suppresses the lattice thermal conductivity to a minimum value of 0.97 W K -1 m -1 at 300 K, while doping Ag significantly enhances the power factor to a peak value of 17.7 μW cm -1 K -2 at 500 K and reduces the bipolar thermal conductivity. As a result of the simultaneously optimized electrical and thermal transport, a peak zT of 1.2 is achieved for Zn 0.698 Ag 0.002 Cd 0.3 Sb at 600 K, which is comparable with the best values reported for Zn 4 Sb 3 -based compounds. Moreover, a current stress test confirms that introducing Ag and Cd does not degrade the good stability of ZnSb under an electric field. The phase composition and thermoelectric performance of Zn 0.698 Ag 0.002 Cd 0.3 Sb are not changed even under a high current density of 50 A cm -2 , showing much better stability than Zn 4 Sb 3 . This study would accelerate the real application of ZnSb-based compounds in the field of waste heat harvesting.