A Korean research team has developed a novel thermoelectric material and generator (TEG) that leverages sponge-like carbon nanotube (CNT) structures, improving the limitations of organic thermoelectric materials while retaining flexibility. The resulting device is expected to be useful in powering small-scale wearable sensors through thermal energy harvesting.
The research is published in the journal Carbon Energy.
Led by Drs. Mijeong Han and Young Hun Kang at the Korea Research Institute of Chemical Technology (KRICT), the team combined carbon nanotubes with Bi0.45Sb1.55Te3 (BST) in a porous foam structure to maximize thermoelectric performance.
While conventional thermoelectric materials are typically metal-based and rigid, the use of CNTs allows for light weight and mechanical flexibility—although previous attempts have resulted in low thermoelectric performance and poor durability.
To overcome these challenges, the team developed a proprietary fabrication technique that transforms CNTs into bulk foams rather than thin films. This was achieved by heating and solidifying a powder-filled mold to create a sponge-like structure.
A method was also developed to uniformly distribute the thermoelectric BST particles within the foam’s pores, improving both mechanical stability and thermoelectric performance.
As a result, the CNT/BST foam achieved a zT of 7.8 × 10-3—5.7 times higher than that of pristine CNT foam. When applied to a flexible thermoelectric generator and tested on a glass tube at a temperature difference of 21.8 K, the device generated output power of 15.7 µW—enough to operate wearable sensors.
The concave TEG conforming to a cylindrical glass tube. Output voltage of the concave TEG with different water temperatures in the glass tube. The water flowed for 10 s and stopped for 20 s. Simulated temperature distributions inside the TE legs with hot-water and cold-water flows. © Korea Research Institute of Chemical Technology (KRICT)
Durability was confirmed through 10,000-cycle bending tests, with minimal performance loss. Moreover, the entire fabrication process takes just four hours, compared to over three days for traditional CNT-based TEGs, highlighting the material’s excellent scalability.
The team plans to further enhance thermoelectric efficiency through doping strategies and aims for commercialization by 2030. Future applications include integration into thermal management systems for batteries and AI data centers, as well as wearable and autonomous electronic devices.
“This study represents a significant step forward in developing flexible, self-powered devices,” said the researchers, adding that the material’s moldability and durability open new frontiers in energy harvesting.
More information:
Myeong Hoon Jeong et al, High‐performance and flexible thermoelectric generator based on a robust carbon nanotube/BiSbTe foam, Carbon Energy (2024). DOI: 10.1002/cey2.650
Provided by
National Research Council of Science and Technology
Citation:
Sponge-like carbon nanotube thermoelectric generator easily molds to complex shapes and powers sensors (2025, April 29)
