Lead Free thermoelectric material with about 15% efficiency for capturing waste heat

Physicists at the University of Houston’s physics department and the Texas Center for Superconductivity are working on an innovation that could boost vehicle mileage by 5 percent and power plant and industrial processing performance as much as 10 percent.

Their research uses non-toxic materials – tin telluride, with the addition of the chemical element indium – for waste heat recovery.

A ZT of 1.1 for 800K is about 15% heat to electricity conversion efficiency

PNAS – High thermoelectric performance by resonant dopant indium in nanostructured SnTe

Abstract
From an environmental perspective, lead-free SnTe would be preferable for solid-state waste heat recovery if its thermoelectric figure-of-merit could be brought close to that of the lead-containing chalcogenides. In this work, we studied the thermoelectric properties of nanostructured SnTe with different dopants, and found indium-doped SnTe showed extraordinarily large Seebeck coefficients that cannot be explained properly by the conventional two-valence band model. We attributed this enhancement of Seebeck coefficients to resonant levels created by the indium impurities inside the valence band, supported by the first-principles simulations. This, together with the lower thermal conductivity resulting from the decreased grain size by ball milling and hot pressing, improved both the peak and average nondimensional figure-of-merit (ZT) significantly. A peak ZT of ∼1.1 was obtained in 0.25 atom % In-doped SnTe at about 873 K.

4 pages of supplemental material

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