Rational design from materials to devices enables an efficiency of 10.5% based on thermoelectric (Bi, Sb)2Te3 and Mg3(Bi, Sb)2 for power generation

Abstract

p-Type (Bi, Sb)₂Te₃ is the most excellent thermoelectric material near room temperature; however, the drastically declined performance makes it incapable of coping with low-grade waste heat recovery scenarios above 500 K. Herein, firstly, a great advance in thermoelectric performance is realized through reasonable composition control and microstructure design, including lithium acceptor doping to improve the electrical transport performance and subsequent Te addition to suppress the donor-like effect to further fine-tune the power factor, as well as the construction of dispersed nanopores, which leads to very low thermal conductivity. As a result, a highly competitive ZT of 1.42 at 373 K and a ZT_ave of 1.23 from 303 K to 523 K are achieved concurrently. Secondly, (Bi, Sb)₂Te₃ and its higher-temperature analogue Sb₂Te₃ are organized in a segmented structure by one-step sintering to broaden the temperature range. Similarly, optimized Mg₃(Sb, Bi)₂ materials with different high-performance temperature ranges are used to prepare the n-type segmented leg. Finally, a 2-pair module is fabricated, showing an efficiency of up to 10.5% and a power density of 0.53 W cm⁻² with a temperature difference of 380 K. This work provides robust evidence for the high potential of (Bi, Sb)₂Te₃/Mg₃(Bi, Sb)₂ segmented modules for waste heat recovery.