Reviewed by Lexie CornerAug 19 2024
A joint research team led by Professor Jae Sung Son of POSTECH and Saniya LeBlanc of George Washington University has successfully developed a new geometry for thermoelectric materials—previously limited to cuboid shapes—through geometric design and 3D printing processes. This research was published in Nature Energy.
Schematic representation of efficiency enhancement in thermoelectric generators through geometric design and the induction of micro-layered defects in 3D-printed materials. [Figure a] shows the eight different geometries designed in this study and the optimization of 3D printing and heat treatment processes to create high-density dislocation defects. [Figure b] illustrates the thermoelectric figure-of-merit (ZT) as a function of heat treatment temperature, showing an increase to 2.0 when treated at 1233 K. [Figure c] displays the power generation efficiency of the eight different thermoelectric geometries. The dotted lines represent the simulated data, while the points indicate the actual measured efficiency. Image Credit: Pohang University of Science and Technology
The National Research Foundation of Korea, chaired by Lee Kwang-bok, announced a significant improvement in power generation efficiency through an innovative thermoelectric design. This new method reshapes thermoelectric materials into an hourglass form, enhancing their efficiency and making them essential for converting waste heat into energy. Unlike previous studies that focused solely on the material properties of thermoelectric substances, this novel approach is expected to have wide-ranging applications in thermoelectric power generation.
Thermoelectric technology converts heat into electricity, drawing interest as a sustainable renewable energy source capable of transforming heat from engines, factories, and even human body heat into electricity. Solid thermoelectric semiconductor materials are typically used in this technology.
Traditionally, research on thermoelectric generators has focused on improving the intrinsic characteristics of thermoelectric materials (ZT). However, despite advancements in ZT, the efficiency of thermoelectric generators has not yet reached a practical level for everyday use, highlighting the need for a new approach beyond just material improvements.
In this study, the research team demonstrated that optimizing the design and composition of thermoelectric materials could lead to substantial increases in power production efficiency. Through simulations of eight different geometric structures, including the traditional cuboid shape and the hourglass shape, the team found that the hourglass structure consistently outperformed other designs under all power generation conditions. Each structure's power generation efficiency was meticulously measured, revealing the hourglass design's superior performance.
The research team utilized 3D printing techniques to create thermoelectric materials with complex shapes and high-density micro-layered flaws. These materials reduced heat conductivity and increased the thermoelectric performance index (ZT) to an impressive 2.0—the highest value achieved so far for 3D-printed thermoelectric materials.
Building on these findings, the researchers constructed thermoelectric generators using eight different configurations and evaluated their performance. They found that the hourglass-shaped generator outperformed the conventional rectangular-based generator by approximately 3.6 times.
This research is the first instance where efficiency has been improved by three-dimensional geometry of the material that controlled thermal and electrical transport, instead of conventional microstructure-focused research on thermoelectric materials. It is expected that this approach can be universally applied to all thermoelectric materials and can also be utilized in thermoelectric cooling technologies.
Jae Sung Son, Professor, Department of Chemical Engineering, Pohang University of Science and Technology
The research was supported by funding from the National Research Foundation of Korea, the Ministry of Science and ICT's Mid-Career Researcher Program, and the Nano and Materials Technology Development Program.
Journal Reference:
Choo, S., et. al. (2024) Geometric design of Cu2Se-based thermoelectric materials for enhancing power generation. Nature Energy. doi.org/10.1038/s41560-024-01589-5