Selective Dissolution-Derived Nanoporous Design of Impurity-Free Bi 2 Te 3 Alloys with High Thermoelectric Performance

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 19; no. 14; p. e2205202
• Main Authors: Lee, Seunghyeok, Jung, Sung-Jin, Park, Gwang Min, Na, Min Young, Kim, Kwang-Chon, Hong, Junpyo, Lee, Albert S, Baek, Seung-Hyub, Kim, Heesuk, Park, Tae Joo, Kim, Jin-Sang, Kim, Seong Keun
• Format: Journal Article
• Language: English
• Published: Germany 01-04-2023
• Subjects: Bi 2Te 3; porous materials; selective dissolution; thermoelectrics; KCl
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202205202

Thermoelectric technology, which has been receiving attention as a sustainable energy source, has limited applications because of its relatively low conversion efficiency. To broaden their application scope, thermoelectric materials require a high dimensionless figure of merit (ZT). Porous structuring of a thermoelectric material is a promising approach to enhance ZT by reducing its thermal conductivity. However, nanopores do not form in thermoelectric materials in a straightforward manner; impurities are also likely to be present in thermoelectric materials. Here, a simple but effective way to synthesize impurity-free nanoporous Bi
Sb
Te
via the use of nanoporous raw powder, which is scalably formed by the selective dissolution of KCl after collision between Bi
Sb
Te
and KCl powders, is proposed. This approach creates abundant nanopores, which effectively scatter phonons, thereby reducing the lattice thermal conductivity by 33% from 0.55 to 0.37 W m
K
. Benefitting from the optimized porous structure, porous Bi
Sb
Te
achieves a high ZT of 1.41 in the temperature range of 333-373 K, and an excellent average ZT of 1.34 over a wide temperature range of 298-473 K. This study provides a facile and scalable method for developing high thermoelectric performance Bi
Te
-based alloys that can be further applied to other thermoelectric materials.