High thermoelectric energy conversion efficiency of a unicouple of n-type Mg3Bi2 and p-type Bi2Te3. (July 2021) - Liang, Z.
Abstract: Low-grade heat harvesting by thermoelectric technology can contribute to efficient energy utilization. However, the large-scale application of thermoelectric devices is partially hindered by their unsatisfactory performance and relatively high cost. Here we prepared a cost-effective n-type Mg3 Bi2 -based compound with a peak zT of 1.24 at 573 K. A unicouple comprised of n-type Mg3.2 Bi1.29 Sb0.7 Te0.01 and p-type Bi0.2 Sb1.8 Te3 was constructed and its energy conversion efficiency was evaluated. The unicouple exhibited a record-high efficiency of (9.0 ± 0.5)% or (8.3 ± 0.4)% [considering the radiation heat loss] under a temperature difference of 265 K at the hot-side temperature of 573 K. Our results demonstrate the great potential of Mg3 Bi2 -based materials for low-grade heat recovery. Graphical abstract: Image 1 Highlights: The n-type Mg3.2 Bi1.29 Sb0.7 Te0.01 compound exhibited a peak zT of 1.24 at 573 K. A unicouple comprised of n-type Mg3.2 Bi1.29 Sb0.7 Te0.01 and p-type Bi0.2 Sb1.8 Te3 was constructed and evaluated. A record-high efficiency of ∼9.0% could be achieved in the unicouple under a temperature difference of 265 K.