Yonsei University Team Develops High-Efficiency Thermoelectric Material to Convert Waste Heat to Electricity

Researchers at Yonsei University have developed a next-generation thermoelectric material capable of converting waste heat into electrical energy, a significant advancement for energy harvesting and sustainable power generation. The team, led by Professor Kim Woo-chul of the Department of Mechanical Engineering, focused on overcoming the limitations of existing thermoelectric materials.

The newly developed material is an eco-friendly tin selenide (SnSe) enhanced with a 3% addition of manganese (Mn). This modification successfully boosted electrical conductivity while effectively inhibiting heat transfer. The resulting thermoelectric performance index (zT) reached a peak of 2.3, setting a new world record for polycrystalline SnSe-based thermoelectric materials.

Thermoelectric materials generate electricity directly from temperature differences, offering a promising clean energy solution as they require no fuel or rotating parts. However, a major challenge has been the inherent trade-off: materials that conduct electricity well also tend to conduct heat efficiently, hindering overall performance. This has made it difficult to simultaneously improve both properties.

To address this, the research team engineered the material to form manganese selenide (MnSe) magnetic nanoparticles, approximately 5-10 nanometers in size, within the SnSe structure. These nanoparticles exhibit superparamagnetism, effectively controlling electron movement to enhance electrical conductivity and maintain high thermoelectric efficiency. Additionally, some manganese atoms substituted into the SnSe crystal structure weakened atomic bonds, inducing "lattice softening." This phenomenon reduced the movement of heat-carrying lattice vibrations (phonons), decreasing thermal conductivity by about 31% and effectively preventing heat loss.

This research is significant not only for improving the performance of a specific material but also for proposing a novel design concept that merges magnetism and lattice engineering. The team believes this technology can be applied to various thermoelectric materials, potentially serving as a core component for energy harvesting systems that recover waste heat from industrial processes, automobiles, power plants, and electronic devices, as well as for wireless power transfer technologies. The study, supported by the National Research Foundation of Korea, was published in the journal Advanced Functional Materials.