Technology Commercialization and Partnerships | BSA 09-27: Synthesis of High-Efficiency Thermoelectric Materials

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Categories: advanced materials, energy

BSA 09-27: Synthesis of High-Efficiency Thermoelectric Materials

BNL Reference Number: BSA 09-27

Patent Status: Application Number 20110120517 was published on May 26, 2011

Summary

Nanocrystalline inclusions in the thermoelectric matrix may limit thermal conductivity while not interfering with electrical conductivity.

Thermoelectric materials must exhibit both high electrical conductivity and low thermal conductivity in order to usefully convert heat to electricity or vice versa. This combination, however, is traditionally very difficult to achieve. These new non-equilibrium processing techniques produce thermoelectric materials that overcome that challenge, leading to high efficiency thermoelectric devices that can generate electricity from waste heat or provide compact heating or cooling.

Description

Bulk thermoelectric materials were heated above their melting temperature, then cooled at a rate of at least 100,000K/s, and up to in excess of 1,000,000K/s, by melt-spinning. The resulting nanoribbons of material were then hot-pressed or subjected to spark-plasma sintering for a matter of minutes. The resulting thermoelectric material had ZT about 20% to 50% higher than the bulk value. For comparison, pellets with the same composition were also prepared using the conventional solid-state reaction followed by long term annealing. Ultimately, the non-equilibrium synthesized samples have higher power factors and lower thermal conductivity, resulting in a highly efficient material.

Benefits

These non-equilibrium manufacturing techniques create materials with a very high thermoelectric figure of merit with less processing time and superior end results. All three processes (melt-spinning, hot isostatic pressing, and spark-plasma sintering) use standard industrial equipment. The materials do not degrade the equipment, and can be “dropped” into the production line.

Applications and Industries

This process can yield highly efficient materials for thermoelectric devices, including generators, heaters, and coolers. Depending on the material, applications may include generation of electricity from waste heat, as from industrial processes or automotive exhaust streams.