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Berkeley Lab scientists generate low-cost, hybrid thermoelectric materials

Scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) have constructed a low-cost, nanoscale composite hybrid thermoelectric material by wrapping a polymer that conducts electricity around a nanorod of tellurium—a metal coupled with cadmium in today’s most cost-effective solar cells.

(Thermoelectric (TE) devices produce a voltage potential as a byproduct of a difference in temperature; that potential can then be used to drive an electrical current. Such devices can recover some of the energy embedded in waste heat, such as that produced by the exhaust gas of an IC engine. (Earlier post.) A number of automakers are exploring the potential for thermoelectric generators (TEGs) for waste heat recovery.)

The composite material is easily spin cast or printed into a film from a water-based solution. Along with its ease of manufacture, this hybrid material also has a thermoelectric figure of merit (room temperature ZT ~0.1) thousands of times greater than either the polymer or nanorod alone—a crucial factor in boosting device performance.

Historically, high-efficiency thermoelectrics have required high-cost, materials-intensive processing. By engineering a hybrid of soft and hard materials using straightforward flask chemistry in water, we’ve developed a route that provides respectable efficiency with a low cost to production.

—Jeff Urban, Deputy Director of the Inorganic Nanostructures Facility at the Molecular Foundry

A paper on the research was published in the ACS journal Nano Letters.

The Molecular Foundry is one of the five DOE Nanoscale Science Research Centers (NSRCs), national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative.

The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos National Laboratories.

Resources

  • Kevin C. See, Joseph P. Feser, Cynthia E. Chen, Arun Majumdar, Jeffrey J. Urban, and Rachel A. Segalman (2010) Water-Processable Polymer-Nanocrystal Hybrids for Thermoelectrics. Nano Lett., Article ASAP doi: 10.1021/nl102880k

Comments

Reel$$

Sounds promising.

HarveyD

Could anybody translate Respectable efficiency into numbers?

What percentage of the wasted energy recovery would be required to offset the initial installation (over 8 years or so) ?

SJC

They were quoting 5% conversion, since half goes out the cooling system and half out the exhaust, they will recover very little. It might be good for large 18 wheel hybrid trucks where there is a LOT of waste heat.

TheOne

The (ZT) or "dimensionless thermoelectric figure of merit" in Bismuth Antimony Telluride (BiSbTe) bulk alloys has remained around 1 for more than 50 years. Nanostructured Bismuth Antimony Telluride Bulk Alloys show that a peak ZT of 1.4 at 100°C can be achieved in a p-type nanocrystalline BiSbTe bulk alloy. These nanocrystalline bulk materials were made by hot pressing nanopowders that were ball-milled from crystalline ingots under inert conditions. Electrical transport measurements, coupled with microstructure studies and modeling, show that the ZT improvement is the result of low thermal conductivity caused by the increased phonon scattering by grain boundaries and defects. More importantly, ZT is about 1.2 at room temperature and 0.8 at 250°C, which makes these materials useful for cooling and power generation. Cooling devices that use these materials have produced high-temperature differences of 86°, 106°, and 119°C with hot-side temperatures set at 50°, 100°, and 150°C, respectively. This discovery sets the stage for use of a new nanocomposite approach in developing high-performance low-cost bulk thermoelectric materials.

3PeaceSweet

You could probably get 20 or 30kW of usable heat from an ICE at cruise, assuming you can get 5% as usable electricity that might be 1kW, not masses but should be enough to run electrical loads

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