Scalable synthesis of n-type Mg3Sb2-xBix for thermoelectric applications

The highly efficient n-type Mg3Sb2-Bi-x(x) thermoelectric materials hold great promise for application in power generation as well as refrigeration. Currently, n-type Mg3Sb2-Bi-x(x) compounds with high zTs can be easily reproduced on a laboratory scale with similar to 10 g per batch. However, scaling up the synthesis of Mg3Sb2-Bi-x(x) with uniform high thermoelectric performance, which is critical for promoting this compound for practical applications, has yet to be achieved. Here we report a scalable preparation method based on Simoloyer ball-milling, which allows us to obtain over 1 kg Mg3.1Sb1.5Bi0.49Te0.01 powder in a single batch. Subsequently, samples with different diameters (ranging from a half inch to two inches) were successfully prepared and their thermoelectric performance was found to be comparable. In addition, a two-inch sample was sectioned into several parts, and the thermoelectric properties of the separate parts are also similar, indicating the high uniformity of the prepared large-scale sample. Importantly, the single-leg Mg3.1Sb1.5Bi0.49Te0.01 attains a high energy conversion efficiency of similar to 12.9% under a temperature difference of similar to 480 K at the hot-side temperature of 773 K. This study represents a step toward the practical application of Mg3Sb2-Bi-x(x) for thermoelectric power generation. (C) 2020 Elsevier Ltd. All rights reserved.