Method of improving thermoelectric figure of merit of high efficiency thermoelectric materials
View Patent ↗A method of improving the thermoelectric figure of merit (ZT) of a high-efficiency thermoelectric material is disclosed. The method includes the addition of fullerene (C 60 ) clusters between the crystal grains of the material. It has been found that the lattice thermal conductivity (κ L ) of a thermoelectric material decreases with increasing fullerene concentration, due to enhanced phonon-large defect scattering. The resulting power factor (S 2 /ρ) decrease of the material is offset by the lattice thermal conductivity reduction, leading to enhanced ZT values at temperatures of between 350 degrees K and 700 degrees K.
1. A method of increasing a thermoelectric figure of merit of a thermoelectric material, comprising:
providing at least a first metal element containing precursor material and a second metal element containing precursor material, each precursor material being in powder form and together comprising elements of a thermoelectric material;
mixing the precursor materials with fullerene to form a mixture;
reacting the mixture under an inert gas atmosphere to form the thermoelectric material in crystalline form; and
sintering the reacted mixture to form fullerene clusters dispersed between crystal grains of the thermoelectric material.
2. The method of claim 1 wherein said thermoelectric material comprises a skutterudite.
3. The method of claim 1 wherein said fullerene is present in said thermoelectric material in a quantity of at least about 0.5 mass percent.
4. The method of claim 3 wherein said thermoelectric material comprises CoSb 3 .
5. The method of claim 1 wherein said thermoelectric material is a clathrate or a half-Heusler.
6. The method of claim 1 wherein the first metal element containing precursor material comprises cobalt and the second metal element containing precursor material comprises antimony, and wherein the cobalt and antimony are present in a cobalt:antimony molar ratio of about 1:3.
7. The method of claim 1 wherein sintering comprises spark plasma sintering.
8. The method of claim 7 wherein said fullerene is present in said thermoelectric material in a quantity of at least about 0.5 mass percent.