Low-temperature high-performance thermoelectric material and preparation method thereof

Abstract

A low-temperature high-performance thermoelectric material possesses a chemical formula of (Ag.sub.yCu.sub.2y).sub.1xTe.sub.1zSe.sub.z, wherein 0.025x0.075, 0.6y1.4, 0<z0.25, diffraction peaks of a main phase of the thermoelectric material are indexed as a cubic structure at room temperature of 300 K, a highest ZT value between 300 K and 673 K is in range of 0.4 to 1.6, an average ZT value (ZT).sub.avg is in range of 0.2 to 1.4. The highest ZT value of this material at the room temperature is comparable to that of Bi.sub.2Te.sub.3, which is an excellent complement to existing low-temperature thermoelectric materials. At the same time, the present invention also indicates a new strategy to improve the low-temperature thermoelectric performance of Cu.sub.2X-based (here, X is S, Se, Te) materials, and lays a foundation for the application of Cu.sub.2X-based materials in the field of low-temperature thermoelectricity.

Claims

1. A thermoelectric material, which possesses a chemical formula of (Ag.sub.yCu.sub.2y).sub.1xTe.sub.1zSe.sub.z, wherein: 0.025x0.075, 0.65y1.4, 0<z0.25.

2. The thermoelectric material, as recited in claim 1, wherein: x=0.025, 0, 0.005, 0.01, or 0.075; y=0.6, 0.8, 0.9, 1, 1.2, or 1.4; z=0.05, 0.1, 0.12, 0.2, or 0.25.

3. The thermoelectric material, as recited in claim 1, wherein: (x, y, z)=(0, 1, 0.1) or (0.005, 1, 0.1).

4. A preparation method of a thermoelectric material, which comprises steps of: (S1) charging, which comprises: respectively weighing Ag, Cu, Te and Se according to a stoichiometric ratio of (Ag.sub.yCu.sub.2y).sub.1xTe.sub.1zSe.sub.z, wherein 0.025x0.075, 0.6y1.4, 0<z0.25, and then loading the Ag, Cu, Te and Se with ball-grinding balls into a ball-grinding tank, and then sealing in an argon atmosphere inside a glove box; (S2) ball-grinding, which comprises: loading the ball-grinding tank into a high-energy ball mill machine, mechanically alloying for 10-20 h, and obtaining (Ag.sub.yCu.sub.2y).sub.1xTe.sub.1zSe.sub.z powders; and (S3) sintering the powders obtained by the step of (S2) at a temperature in a range of 200 C. to 500 C. for 3-10 min, and obtaining a (Ag.sub.yCu.sub.2y).sub.1xTe.sub.1zSe.sub.z bulk thermoelectric material.

5. The thermoelectric material, as recited in claim 4, wherein: in the step of (S1), x=0.025, 0, 0.005, 0.01, or 0.075, y=0.6, 0.8, 0.9, 1, 1.2, or 1.4, z=0.05, 0.1, 0.12, 0.2, or 0.25.

6. The thermoelectric material, as recited in claim 4, wherein: in the step of (S2), ball-grinding is performed for 15 h.

7. The thermoelectric material, as recited in claim 4, wherein: in the step of (S3), hot press sintering or spark plasma sintering is performed with a graphite die at 218 C. for 5 min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a room-temperature XRD (X-ray diffraction) pattern of a AgCuTe.sub.0.9Se.sub.0.1 thermoelectric material according to a first embodiment of the present invention, wherein diffraction peaks of a main phase are indexed as a face-centered cubic (FCC) structure with a lattice constant of 6.216 .

[0023] FIG. 2 is a room-temperature XRD pattern of a AgCuTe.sub.1zSe.sub.z (here, z=0.05, 0.1, 0.12, 0.2, or 0.25) thermoelectric material according to a second embodiment of the present invention, wherein diffraction peaks of a main phase for all materials are indexed as a FCC structure.

[0024] FIG. 3 is a room-temperature XRD pattern of the Ag.sub.yCu.sub.2yTe.sub.0.9Se.sub.0.1 (here, y=0.6, 0.8, 0.9, 1, 1.2, or 1.4) thermoelectric material according to a third embodiment of the present invention, wherein diffraction peaks of a main phase for all materials are indexed as a FCC structure.

[0025] FIG. 4 demonstrates a ZT value-temperature characteristic curve of a (AgCu).sub.1xTe.sub.0.9Se.sub.0.1 (here, x=0.025, 0, 0.005, 0.01, or 0.075) thermoelectric material according to a fourth embodiment of the present invention.

[0026] FIG. 5 demonstrates a ZT value-temperature characteristic curve of a (AgCu).sub.0.995Te.sub.0.9Se.sub.0.1 thermoelectric material according to a fifth embodiment of the present invention and other Cu.sub.2X-based materials, wherein the ZT values of the (AgCu).sub.0.995Te.sub.0.9Se.sub.0.1 thermoelectric material are much higher than those of other Cu.sub.2X-based materials in a temperature range from 300 K to 673 K; the ZT value-temperature characteristic curve of other Cu.sub.2X-based materials derive from previously reported studies: Cu.sub.1.97S (Y. He et al, Adv Mater, 26: 3974-8, 2014), Cu.sub.2Se (H. Liu, Nat Mater, 11: 422-5, 2012), Cu.sub.2.075Se (J.-Y. Tak, Chemistry of Materials, 30: 3276-3284, 2018), Cu.sub.2Te (Y. He, NPG Asia Materials, 7: e210-e210, 2015), Cu.sub.2S.sub.0.52Te.sub.0.48 (Y. He, Adv Mater. 27: 3639-44, 2015), Ag.sub.0.94CuSe (H. Chen, Inorg Chem, 54: 867-71, 2015).

[0027] FIG. 6 demonstrates average ZT values [(ZT).sub.avg] between 300 K and 673 K of the (AgCu).sub.0.995Te.sub.0.9Se.sub.0.1 thermoelectric material according to the above fifth embodiment of the present invention and other Cu.sub.2X-based materials, wherein the (ZT).sub.avg of the (AgCu).sub.0.995Te.sub.0.9Se.sub.0.1 thermoelectric material according to the above fifth embodiment of the present invention is 2-3 times that of other Cu.sub.2X-based materials, the (Z).sub.avg are calculated by a formula of (ZT).sub.avg=Z.sub.intT.sub.ave, where

[00001]$Z_{\mathrm{int}}=\frac{1}{T_h-T_c}.Math.{}_{T_c}^{T_h}.Math.Z\left(T\right).Math.\mathrm{dT},$

Z(T) refers to FIG. 5,

[00002]$T_{\mathrm{avg}}=\frac{T_h+T_c}{2},$

T.sub.c=300 K, T.sub.h=673 K.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0028] A preparation method of a low-temperature high-performance thermoelectric material comprises steps of:

[0029] (S1) charging, which comprises: respectively weighing silver (Ag), copper (Cu), tellurium (Te), and selenium (Se) according to a stoichiometric ratio of (Ag.sub.yCu.sub.2y).sub.1xTe.sub.1zSe.sub.z, wherein 0.025x0.075, 0.6y1.4, 0<z0.25, and then loading the Ag, Cu, Te and Se with ball-grinding balls into a ball-grinding tank, and then sealing in an argon atmosphere inside a glove box;

[0030] (S2) ball-grinding, which comprises: loading the ball-grinding tank into a high-energy ball mill machine, mechanically alloying for 10-20 h, and obtaining (Ag.sub.3Cu.sub.2y).sub.1xTe.sub.1zSe.sub.z powders; and

[0031] (S3) sintering, which comprises: hot press sintering or spark plasma sintering the powders obtained by the step of (S2) with a graphite die at a temperature in a range of 200 C. to 500 C. for 3-10 min, and obtaining a (Ag.sub.yCu.sub.2y).sub.1xTe.sub.1zSe.sub.z bulk thermoelectric material.

[0032] Further, in the step of (S1), x=0.025, 0, 0.005, 0.01, or 0.075, y=0.6, 0.8, 0.9, 1, 1.2, or 1.4, z=0.05, 0.1, 0.12, 0.2, or 0.25.

[0033] Further, in the step of (S2), ball-grinding is performed for 15 h.

[0034] Further, in the step of (S3), the sintering is performed at 218 C. for 5 min.

First Embodiment

[0035] (S1) Charging, which comprises: respectively weighing 2.9342 g of silver (Ag), 1.7282 g of copper (Cu), 3.1229 g of tellurium (Te), and 0.2147 g of selenium (Se) according to a stoichiometric ratio of AgCuTe.sub.0.9Se.sub.0.1, and then loading the Ag, Cu, Te and Se withball-grinding balls into a ball-grinding tank, and then sealing in an argon atmosphere inside a glove box;

[0036] (S2) Ball-grinding, which comprises: loading the ball-grinding tank into a high-energy ball mill machine, mechanically alloying for 15 h, and obtaining AgCuTe.sub.0.9Se.sub.0.1 powders; and

[0037] (S3) Sintering, which comprises: hot press sintering the powders obtained by the step of (S2) with a graphite die at 218 C. for 5 min, and obtaining a AgCuTe.sub.0.9Se.sub.0.1 bulk thermoelectric material.

Second Embodiment

[0038] (S1) Charging, which comprises: respectively weighing silver (Ag), copper (Cu), tellurium (Te), and selenium (Se) according to a stoichiometric ratio of AgCuTe.sub.1zSe.sub.z, wherein z=0.05, 0.1, 0.12, 0.2, or 0.25 and a total amount of the Ag, Cu, Te and Se is 8 g, and then loading the Ag, Cu, Te and Se with ball-grinding balls into a ball-grinding tank, and then sealing in an argon atmosphere inside a glove box;

[0039] (S2) Ball-grinding, which comprises: loading the ball-grinding tank into a high-energy ball mill machine, mechanically alloying for 15 h, and obtaining AgCuTe.sub.1zSe.sub.z powders, wherein z=0.05, 0.1, 0.12, 0.2, or 0.25; and

[0040] (S3) Sintering, which comprises: hot press sintering the powders obtained by the step of (S2) with a graphite die at 200 C. for 5 min, and obtaining a AgCuTe.sub.1zSe.sub.z bulk thermoelectric material, wherein z=0.05, 0.1, 0.12, 0.2, or 0.25.

Third Embodiment

[0041] (S1) Charging, which comprises: respectively weighing silver (Ag), copper (Cu), tellurium (Te), and selenium (Se) according to a stoichiometric ratio of Ag.sub.yCu.sub.2yTe.sub.0.9Se.sub.0.1, wherein y=0.6, 0.8, 0.9, 1, 1.2, or 1.4 and a total amount of the Ag, Cu, Te and Se is 8 g, and then loading the Ag, Cu, Te and Se with ball-grinding balls into a ball-grinding tank, and then sealing in an argon atmosphere inside a glove box;

[0042] (S2) Ball-grinding, which comprises: loading the ball-grinding tank into a high-energy ball mill machine, mechanically alloying for 15 h, and obtaining Ag.sub.yCu.sub.2yTe.sub.0.9Se.sub.0.1 powders, wherein y=0.6, 0.8, 0.9, 1, 1.2, or 1.4; and

[0043] (S3) Sintering, which comprises: hot press sintering the powders obtained by the step of (S2) with a graphite die at 200 C. for 5 min, and obtaining a Ag.sub.yCu.sub.2yTe.sub.0.9Se.sub.0.1 bulk thermoelectric material, wherein y=0.6, 0.8, 0.9, 1, 1.2, or 1.4.

Fourth Embodiment

[0044] (S1) Charging, which comprises: respectively weighing silver (Ag), copper (Cu), tellurium (Te), and selenium (Se) according to a stoichiometric ratio of (AgCu).sub.1xTe.sub.0.9Se.sub.0.1, wherein x=0.025, 0, 0.005, 0.01, or 0.075 and a total amount of the Ag, Cu, Te and Se is 8 g, and then loading the Ag, Cu, Te and Se with ball-grinding balls into a ball-grinding tank, and then sealing in an argon atmosphere inside a glove box;

[0045] (S2) Ball-grinding, which comprises: loading the ball-grinding tank into a high-energy ball mill machine, mechanically alloying for 15 h, and obtaining (AgCu).sub.1xTe.sub.0.9Se.sub.0.1 powders, wherein x=0.025, 0, 0.005, 0.01, or 0.075; and

[0046] (S3) Sintering, which comprises: hot press sintering the powders obtained by the step of (S2) with a graphite die at 200 C. for 5 min, and obtaining a (AgCu).sub.1xTe.sub.0.9Se.sub.0.1 bulk thermoelectric material, wherein x=0.025, 0, 0.005, 0.01, or 0.075.

Fifth Embodiment

[0047] (S1) Charging, which comprises: respectively weighing 2.9406 g of silver (Ag), 1.7146 g of copper (Cu), 3.1297 g of tellurium (Te), and 0.2152 g of selenium (Se) according to a stoichiometric ratio of (AgCu).sub.0.995Te.sub.0.9Se.sub.0.1, and then loading the Ag, Cu, Te and Se with ball-grinding balls into a ball-grinding tank, and then sealing in an argon atmosphere inside a glove box;

[0048] (S2) Ball-grinding, which comprises: loading the ball-grinding tank into a high-energy ball mill machine, mechanically alloying for 15 h, and obtaining (AgCu).sub.0.995Te.sub.0.9Se.sub.0.1 powders; and

[0049] (S3) Sintering, which comprises: hot press sintering the powders obtained by the step of (S2) with a graphite die at 200 C. for 5 min, and obtaining a (AgCu).sub.0.995Te.sub.0.9Se.sub.0.1 bulk thermoelectric material.

[0050] One skilled in the art will understand that the embodiment of the present invention as shown in the drawings and described above is exemplary only and not intended to be limiting.

[0051] It will thus be seen that the objects of the present invention have been fully and effectively accomplished. Its embodiments have been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from such principles. Therefore, the present invention includes all modifications encompassed within the spirit and scope of the following claims.