Bi2Te3‐Based Thermoelectric Modules for Efficient and Reliable Low‐Grade Heat Recovery

Abstract

AbstractBismuth‐telluride‐based alloy has long been considered as the most promising candidate for low‐grade waste heat power generation. However, optimizing the thermoelectric performance of n‐type Bi2Te3 is more challenging than that of p‐type counterparts due to its greater sensitivity to texture, and thus limits the advancement of thermoelectric modules. Herein, the thermoelectric performance of n‐type Bi2Te3 is enhanced by incorporating a small amount of CuGaTe2, resulting in a peak ZT of 1.25 and a distinguished average ZT of 1.02 (300–500 K). The decomposed Cu+ strengthens interlayer interaction, while Ga+ optimizes carrier concentration within an appropriate range. Simultaneously, the emerged numerous defects, such as small‐angle grain boundaries, twin boundaries, and dislocations, significantly suppresses the lattice thermal conductivity. Based on the size optimization by finite element modelling, the constructed thermoelectric module yields a high conversion efficiency of 6.9% and output power density of 0.31 W cm−2 under a temperature gradient of 200 K. Even more crucially, the efficiency and output power little loss after subjecting the module to 40 thermal cycles lasting for 6 days. This study demonstrates the efficient and reliable Bi2Te3‐based thermoelectric modules for broad applications in low‐grade heat harvest.