A new low-cost thermoelectric material developed by a US university can cool down car parts in summer

According to foreign media reports, with the arrival of summer, car steering wheels have become too hot to touch, but new thermoelectric materials can solve this problem. The popularity of thermoelectric devices that can directly convert electrical energy into thermal energy to achieve cooling and heating functions has been hindered by the lack of materials that can maintain high efficiency at room temperature and are cheap.

(Photo source: University of Houston official website)

But now, researchers at the University of Houston and the Massachusetts Institute of Technology report the discovery of a new material that works efficiently at room temperature and requires almost no expensive tellurium, a main ingredient in current state-of-the-art materials.

The researchers of the study said that the material can help prevent electronic devices, vehicles and other components from overheating. In addition, the material is very cheap, but its performance is as good as traditional, more expensive materials. In the future, researchers will focus on narrowing the slight performance gap between this material and traditional materials (bismuth telluride alloy).

The working principle of thermoelectric materials is to use the heat flow from hotter areas to colder areas, and the thermoelectric cooling module will work according to the Peltier effect, which describes the heat absorption and heat release phenomena at the joints of two different conductors depending on the direction of the current.

Thermoelectric materials can also be used to convert waste heat from power plants, car exhaust pipes and other sources into electricity, and many new materials are reported for such applications, which require materials that can operate at higher temperatures.

Thermoelectric cooling modules pose a huge challenge because they must operate in a lower temperature environment, where the thermoelectric conversion figure of merit ZT value of the thermoelectric module is relatively low (this factor depends on temperature). The figure of merit ZT value is an indicator of the working efficiency of thermoelectric materials. The higher the ZT value of thermoelectric materials, the better.

Despite the challenges, at least so far, such thermoelectric cooling modules have great commercial potential, in part because they can operate at lower temperatures for longer periods of time, whereas thermoelectrics become complicated by high temperatures (oxidation and thermal instability) when generating electricity.

The thermoelectric cooling market is growing, with researchers saying the global market for thermoelectric modules was worth about $600 million in 2018 and is expected to reach about $1.7 billion by 2027.

For decades, bismuth-telluride alloys have been considered the best thermal cooling materials, but researchers say the high cost of tellurium has limited its widespread use. Although the cost of tellurium has dropped recently, it is still around $50 per kilogram. In contrast, the new material developed by the researchers is mainly composed of magnesium, which costs about $6 per kilogram.

The new material, made from magnesium and bismuth, was created in a negatively charged (n-type) form that is just as efficient as conventional bismuth-telluride materials, the researchers said. In addition, the material is less expensive, potentially expanding the use of thermoelectric modules for cooling applications.

To make thermoelectric modules from this new material, the researchers combined it with the positive charge carriers in conventional bismuth-telluride alloys, thus requiring only half the tellurium used in most current modules, a significant cost saving since the material costs about one-third of the device. In addition, the new material has better electrical contact capabilities than most nanostructured materials.