Sponge-like carbon nanotube thermoelectric generator easily molds to complex shapes and powers sensors
Thermoelectric figure of merit (zT) enhanced by 5.7 times over conventional CNT foams; Power generation of 15.7μW at a temperature difference of 21.8K—sufficient for operating wearable sensors
image: Schematic illustration showing the fabrication process of the CNT/BST foam with various shapes. Effects of the BST content and annealing temperature on TE properties of the CNT/BST foams. Highly improved zT vlaue of CNT/BST foam compared to pristine CNT foam.
Credit: Korea Research Institute of Chemical Technology(KRICT)
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.
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 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.
Durability was confirmed through 10,000-cycle bending tests, with minimal performance loss. Moreover, the entire fabrication process takes just 4 hours, compared to over 3 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. The paper was featured on the back cover of the January 2025 issue of Carbon Energy (IF: 19.5), with Drs. Mijeong Han and Young Hun Kang as corresponding authors and contributions from Dr. Myeong Hoon Jeong and Eun Jin Bae as first authors.
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KRICT is a non-profit research institute funded by the Korean government. Since its foundation in 1976, KRICT has played a leading role in advancing national chemical technologies in the fields of chemistry, material science, environmental science, and chemical engineering. Now, KRICT is moving forward to become a globally leading research institute tackling the most challenging issues in the field of Chemistry and Engineering and will continue to fulfill its role in developing chemical technologies that benefit the entire world and contribute to maintaining a healthy planet. More detailed information on KRICT can be found at https://www.krict.re.kr/eng/
The study was conducted with support from KRICT’s basic research fund and the Creative Materials Discovery Program of the National Research Foundation of Korea.