KAIST Develops 'Inorganic Thermoelectric Material' Solving Performance-Flexibility Dilemma

A thermoelectric material that resolves the dilemma between thermal energy performance and mechanical flexibility has been developed domestically. This material can be applied to wearable devices such as smart clothing and can maintain stable thermal energy performance even in extreme environments.

KAIST announced on the 21st that a joint research team led by Professor Yeonsik Jeong from the Department of Materials Science and Engineering and Professor Inkyu Park from the Department of Mechanical Engineering, in collaboration with Professor Minwook Oh from Hanbat National University and Dr. Junho Jeong from the Korea Institute of Machinery and Materials, developed a "Bismuth Telluride (Bi2Te3) thermoelectric fiber."

(From left) Jang Han-hwi, Ph.D. candidate at KAIST; Professor Ahn Joon-sung, Department of Control and Instrumentation Engineering, Korea University Sejong Campus; Dr. Jung Yong-rok, Korea Atomic Energy Research Institute; Dr. Jung Joon-ho, Korea Institute of Machinery and Materials; Professor Oh Min-wook, Hanbat National University; Professor Park In-kyu, Department of Mechanical Engineering, KAIST; Professor Jung Yeon-sik, Department of Materials Science and Engineering, KAIST. Provided by KAIST

Thermoelectric materials generate voltage when there is a temperature difference, converting thermal energy into electrical energy. They are also gaining attention as sustainable energy materials because they can recover and recycle waste heat.

Heat sources in daily life, such as the human body, vehicle exhaust pipes, and cooling fins, mostly have curved surfaces. Among these, inorganic thermoelectric materials based on ceramic materials boast high thermoelectric performance but are brittle, making curved fabrication difficult.

Flexible thermoelectric materials using polymer binders can be applied to surfaces of various shapes, but their performance is limited due to the low electrical conductivity and high thermal resistance of polymers. Therefore, polymer additives were necessary for existing flexible thermoelectric materials.

However, the inorganic thermoelectric material developed by the joint research team overcomes the limitations of performance degradation by twisting nanoribbons into fiber-shaped thermoelectric materials without adding polymer additives.

Schematic diagram and actual image of pure inorganic (no polymer additives) fiber-type flexible thermoelectric material. Provided by KAIST

The joint research team, inspired by the flexibility of inorganic nanoribbons, continuously deposited nanoribbons using electron beam deposition technology based on a nano mold and then twisted them into fiber form to produce bismuth telluride inorganic thermoelectric fibers.

The inorganic thermoelectric fibers have higher bending strength than existing thermoelectric materials, and electrical characteristics showed minimal changes even after more than 1,000 repeated bending and tensile tests.

In particular, the thermoelectric device created by the joint research team generates electricity using temperature differences. When clothing is made using fiber-type thermoelectric devices, electricity is produced from body heat, which can power other electronic devices.

The joint research team demonstrated the commercialization potential by embedding thermoelectric fibers in life jackets or clothing to collect energy. Extending this, the team explained that in industrial settings, it is possible to build a high-efficiency energy harvesting system that recycles waste heat by utilizing the temperature difference between hot fluids inside pipes and cold air outside.

Professor Yeonsik Jeong stated, "The inorganic flexible thermoelectric material developed by the joint research team can be applied and utilized in wearable devices such as smart clothing," and added, "It can maintain stable performance even in extreme environments, making commercialization highly likely through further research."

Meanwhile, this research was conducted with support from the Ministry of Science and ICT, the Korea Research Foundation’s Mid-Career Researcher Support Program, the Future Materials Discovery Project, the Global Bio-Convergence Interfacing Materials Center, and support from the Ministry of Trade, Industry and Energy and the Korea Institute for Advancement of Technology.

This content was produced with the assistance of AI translation services.