Abstract
Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for high-efficiency thermoelectric power generation. Here we report a high zT of ∼1.5 at 1,200 K for the p-type FeNbSb heavy-band half-Heusler alloys. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. Both the enhanced point-defect and electron–phonon scatterings contribute to a significant reduction in the lattice thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm−2 at a temperature difference of 655 K. These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability.
Highlights
Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power
The conversion efficiency Z of a thermoelectric device is limited by the Carnot efficiency Zc, and the figure of merit zT of the thermoelectric materials, which is expressed as zT 1⁄4 a2sT/(ke þ kL), where a, s, T, ke and kL are the Seebeck coefficient. respectively, the electrical conductivity, the absolute temperature and the electronic and lattice components of total thermal conductivity k
A peak zT of B1.5 is reached at 1,200 K for FeNb0.88Hf0.12Sb and FeNb0.86Hf0.14Sb, B40% higher than that of Ti-doped FeNbSb19, and the zTs are remarkably higher than other well-known state-of-the-art p-type high-temperature thermoelectric materials over the whole temperature range
Summary
Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for high-efficiency thermoelectric power generation. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm À 2 at a temperature difference of 655 K These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability. Higher carrier concentrations, which demands for higher contents of dopants, are necessary to optimize the power factors
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