Low-thermal-conductivity p-type AgSbSe2-based thermoelectric material and preparation method and application thereof

Abstract

The invention provides a p-type AgSbSe2-based thermoelectric material with low thermal conductivity and a preparation method and application thereof, the chemical composition of the p-type AgSbSe2-based thermoelectric material with low thermal conductivity is Ag1 + ySb1-x-yBixSe2, x is more than 0 and less than or equal to 0.09, y is more than or equal to 0.01 and less than or equal to 0.02, and x and y are the ratio of the amount of substance. The preparation method of the thermoelectric material comprises the following steps: performing vacuum tube sealing on Ag particles, Bi particles, Sb particles and Se particles according to the mass ratio, sintering the sealed quartz tube in a muffle furnace, and cooling to obtain an alloy ingot; and grinding the alloy ingot to obtain powder, and sintering the powder to obtain the p-type AgSbSe2-based thermoelectric material. The p-type AgSbSe2-based thermoelectric material with low thermal conductivity has good conductivity and Zebeck coefficient, and low lattice thermal conductivity at low temperature, and the thermoelectric performance of the thermoelectric material is significantly improved.

Description

Technical Field

[0001] The present invention relates to thermoelectric material technology, and in particular to a low thermal conductivity p-type AgSbSe2-based thermoelectric material, a preparation method and use thereof. Background Art

[0002] Thermoelectric materials generate electricity and cool down through physical effects, and have great application potential in special environments. The performance of thermoelectric materials is characterized by the dimensionless thermoelectric figure of merit ZT, ZT = S 2 σT / κ, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature. Thermoelectric materials have a higher average thermoelectric figure of merit and can operate in a wider temperature range. To obtain a high ZT, it is necessary to reduce the thermal conductivity of the material while maintaining a high electrical conductivity and Seebeck coefficient.

[0003] p-type AgSbSe2-based thermoelectric materials are one of the most promising low-temperature thermoelectric materials in recent years due to their non-toxicity, high performance, rich element content, and lower price of Se than Te. However, their relatively low electrical properties limit the use of AgSbSe2-based thermoelectric materials in a wider temperature range.

[0004] In the prior art, other elements are usually doped into p-type AgSbSe2-based thermoelectric materials to improve the thermoelectric figure of merit of the thermoelectric materials. For example, the prior art "Modulated Fermi level and relaxed lattice strain lead to enhanced thermoelectric performance of AgSbSe2" discloses that the highest thermoelectric figure of merit can reach 1.02 by doping Pb into AgSbSe2-based thermoelectric materials. However, its thermoelectric figure of merit is still low and cannot meet actual needs. Summary of the invention

[0005] The purpose of the present invention is to propose a p-type AgSbSe2-based thermoelectric material with low thermal conductivity to address the problem of low thermoelectric value of existing p-type AgSbSe2-based thermoelectric materials. The thermoelectric material has good electrical conductivity and Seebeck coefficient, as well as low lattice thermal conductivity at low temperatures, which significantly improves the thermoelectric performance of the thermoelectric material.

[0006] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a low thermal conductivity p-type AgSbSe2-based thermoelectric material, the chemical composition of which is Ag 1+y Sb 1-x-y Bi xSe2, where 0<x≤0.09, 0.01≤y≤0.02, where x and y are the ratio of the amount of substance.

[0008] Furthermore, the low thermal conductivity p-type AgSbSe2-based thermoelectric material has a chemical composition of Ag 1+y Sb 1-x-y Bi x Se2, where x=0.09, 0.01≤y≤0.02.

[0009] Furthermore, the low thermal conductivity p-type AgSbSe2-based thermoelectric material has a chemical composition of Ag 1+y Sb 1-x-y Bi x Se2, where x=0.09, y=0.02.

[0010] Furthermore, the low thermal conductivity p-type AgSbSe2-based thermoelectric material has a chemical composition of Ag 1+y Sb 1-x-y Bi x Se2, where x=0.09, y=0.01.

[0011] Another object of the present invention is to disclose a method for preparing a p-type AgSbSe2-based thermoelectric material with low thermal conductivity, comprising the following steps:

[0012] (1) Ag particles, Bi particles, Sb particles and Se particles are placed in a ratio of 3.8 to 4.5 × 10 -3 The sealed quartz tube is vacuum sealed under the pressure of 1.5 Pa, and the sealed quartz tube is placed in a muffle furnace, and the temperature is slowly increased from room temperature to 440-460°C for 12-14 hours, and then the temperature is increased to 850-900°C for 4-6 hours and kept at this temperature for 16-20 hours, and then cooled with the furnace to obtain a smelted alloy ingot;

[0013] (2) Grinding the alloy ingot to obtain powder, and sintering the powder to obtain p-type AgSbSe2-based thermoelectric material.

[0014] Furthermore, the purity of the Ag particles, Bi particles, Sb particles and Se particles in step (1) is greater than or equal to 99.999%.

[0015] Furthermore, the vacuum degree in step (1) is 4.0-4.5×10 -3 Pa.

[0016] Furthermore, the powder particle size in step (2) is 200-300 mesh.

[0017] Furthermore, the sintering in step (2) is spark plasma sintering.

[0018] Furthermore, in step (2), the sintering pressure is 30-40 MPa, the sintering temperature is 400-450° C., and the sintering time is 1-10 min.

[0019] Furthermore, the sintering temperature in step (2) is programmed heating: firstly heating to 400-420°C in 4-6 minutes, then heating to 440-450°C in 1-2 minutes, and keeping at this temperature for 3-5 minutes.

[0020] Another object of the present invention is to disclose a low thermal conductivity p-type AgSbSe2-based thermoelectric material for use in the thermoelectric field.

[0021] The present invention discloses a low thermal conductivity p-type AgSbSe2-based thermoelectric material, a preparation method and a use thereof, which have the following advantages compared with the prior art:

[0022] The present invention, by doping Bi element, jointly regulates the content of Ag and Sb, greatly improves the power factor in the low temperature zone, while maintaining the characteristic of intrinsic low thermal conductivity; thus, the obtained p-type AgSbSe2-based thermoelectric material has excellent thermoelectric performance. The results show that the thermoelectric material provided by the present invention has a good thermoelectric figure of merit and can be used in a wider temperature range (323-673K). BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the Seebeck coefficient of the thermoelectric materials of Examples 1 to 5;

[0024] Figure 2 The electrical conductivity of the thermoelectric materials of Examples 1 to 5 is

[0025] Figure 3 is the power factor of the thermoelectric materials of Examples 1 to 5;

[0026] Figure 4 is the thermal conductivity of the thermoelectric materials of Examples 1 to 5;

[0027] Figure 5 is the lattice thermal conductivity of the thermoelectric materials of Examples 1 to 5;

[0028] Figure 6 is the thermoelectric figure of merit of the thermoelectric materials of Examples 1 to 5. DETAILED DESCRIPTION

[0029] The present invention provides a low thermal conductivity p-type AgSbSe2-based thermoelectric material, the chemical composition of which is Ag 1+y Sb 1-x- y Bi xSe2; wherein 0≤x≤0.09, 0.01≤y≤0.02. In the present invention, by doping Bi element, the content of Ag and Sb is jointly regulated, so that the power factor in the low temperature region is greatly improved, while maintaining the characteristic of intrinsic low thermal conductivity; thus, the obtained p-type AgSbSe2-based thermoelectric material has excellent thermoelectric performance.

[0030] In the present invention, the chemical composition of the p-type AgSbSe2-based thermoelectric material is Ag 1+y Sb 1-x-y Bi x In Se2, x is preferably 0.09. In the present invention, by optimizing the content of the alloy element Bi, the carrier concentration is increased and the conductivity is optimized.

[0031] In the present invention, the chemical composition of the p-type AgSbSe2-based thermoelectric material is Ag 1+y Sb 1-x-y Bi x In Se2, y is preferably 0.01 to 0.02, and more preferably 0.01. In the present invention, by optimizing the contents of Ag and Sb elements, the electrical conductivity is further improved and the lattice thermal conductivity is reduced, thereby synergistically optimizing the thermoelectric performance of the thermoelectric material.

[0032] The p-type AgSbSe2-based thermoelectric material provided by the present invention has intrinsic low thermal conductivity and high Seebeck coefficient, and thus has excellent thermoelectric performance.

[0033] The present invention also provides a method for preparing the p-type AgSbSe2-based thermoelectric material described in the above scheme, comprising the following steps:

[0034] (1) Ag particles, Bi particles, Sb particles, and Se particles were placed at 4.5×10 -3 The sealed quartz tube was sealed under a vacuum pressure of Pa, and the sealed quartz tube was placed in a muffle furnace, and the temperature was slowly increased from room temperature to 450°C for 14 hours, and then the temperature was increased to 900°C for 4 hours and kept at this temperature for 20 hours, and then cooled with the furnace to obtain a smelted alloy ingot;

[0035] (2) Grinding the alloy ingot obtained in step (1) to obtain powder, and sintering the powder to obtain a p-type AgSbSe2-based thermoelectric material.

[0036] The present invention combines Ag particles, Bi particles, Sb particles, and Se particles at 4.5×10 -3 The vacuum tube was sealed under a pressure of Pa, and the sealed quartz tube was placed in a muffle furnace. The temperature was slowly raised from room temperature to 450°C for 14 hours, then raised to 900°C for 4 hours and kept at this temperature for 20 hours. The tube was then cooled with the furnace to obtain a smelted ingot. The obtained alloy ingot was ground to obtain a powder.

[0037] The present invention has no special limitation on the sources of the Ag particles, Bi particles, Sb particles, and Se particles, and commercially available products known to those skilled in the art may be used. In an embodiment of the present invention, the Ag particles are preferably metallic Ag, preferably with a purity of 99.999%; the Bi particles are preferably metallic Bi, preferably with a purity of 99.999%; the Sb particles are preferably metallic Sb, preferably with a purity of 99.999%; and the Se particles are preferably metallic Se, preferably with a purity of 99.999%.

[0038] In the present invention, the ratio of the amount of Ag particles, Bi particles, Sb particles and Se particles is (1-1.02): (0-0.09): (0.9-1): 2. In the present invention, the amount ratio of each element is limited at the same time to ensure that each element can fully play its role and improve the thermoelectric performance of the thermoelectric material.

[0039] In the present invention, the vacuum degree is preferably 4.5×10 -3 Pa. In the present invention, the thermoelectric performance of the thermoelectric material is improved by weighing and grinding the raw materials in air.

[0040] In the present invention, the grinding is preferably manual grinding, and the powder is obtained by grinding to 300 mesh and sieving to ensure the ball milling effect and improve the thermoelectric performance of the product.

[0041] In the embodiment of the present invention, preferably 15 to 20 g of raw material is weighed each time and placed in a quartz tube.

[0042] In the present invention, it is preferred that 300 mesh sieving is performed every 3 to 5 minutes during grinding until the grinding is completed.

[0043] In the present invention, the grinding is preferably performed using an agate mortar.

[0044] After obtaining the ground powder, the present invention sintered the powder to obtain the p-type AgSbSe2-based thermoelectric material.

[0045] In the present invention, the sintering is preferably spark plasma sintering. The present invention reduces the volatilization of Se during the sintering process and improves the performance of the product by limiting the sintering method.

[0046] In the present invention, the sintering pressure is preferably 30-40 MPa, more preferably 30-35 MPa, and most preferably 30 MPa; the sintering temperature is preferably 400-450°C, more preferably 450°C; the sintering time is preferably 1-10 min, more preferably 2-5 min. In the present invention, by limiting the parameters of the sintering process, the mixed powder is fully sintered, the contact reaction of each element is promoted, and the thermoelectric performance of the thermoelectric material is improved.

[0047] In the present invention, the sintering temperature is preferably programmed: the temperature is raised to 400-450°C within 5-6 minutes, and then the temperature is raised to the sintering temperature within 1-2 minutes. In the present invention, by limiting the sintering temperature program, the powder is heated evenly, overheating and decomposition of the raw materials are avoided, and the performance of the thermoelectric material is improved.

[0048] After sintering is completed, the present invention preferably reduces the pressure to 0.05-0.1 MPa within 30-35 minutes, and then cools to room temperature with the furnace.

[0049] The preparation method of the p-type AgSbSe2-based thermoelectric material provided by the present invention promotes the contact reaction of each element by limiting the process parameters of ball milling and sintering, thereby further improving the thermoelectric performance of the thermoelectric material.

[0050] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0051] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0052] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0053] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0054] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0055] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0056] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0057] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0058] Example 1

[0059] This embodiment discloses a low thermal conductivity p-type AgSbSe2-based thermoelectric material, the chemical composition of which is Ag 1.01 Sb 0.9Bi 0.09 Se2.

[0060] The method for preparing the low thermal conductivity p-type AgSbSe2-based thermoelectric material comprises the following steps:

[0061] (1) 5.5134 g of Ag metal particles, 5.5458 g of Sb metal particles, 0.9516 g of Bi metal particles, and 7.9894 g of Se metal particles were weighed in air, wherein the ratio of the elemental substances of Ag metal particles, Sb metal particles, Bi metal particles, and Se metal particles was 1.01:0.9:0.09:2; and the weighed Ag metal particles, Sb metal particles, Bi metal particles, and Se metal particles were placed in a 4.5×10 -3 The vacuum tube was sealed under the pressure of Pa, and the sealed quartz tube was placed in a muffle furnace, and the temperature was slowly raised from room temperature to 450°C for 14 hours, and then raised to 900°C for 4 hours and kept at this temperature for 20 hours, and then cooled with the furnace to obtain a smelted alloy ingot; the ball-milled powder was ground with an agate mortar in a fume hood to 300 mesh and sieved to obtain a precursor powder;

[0062] (2) The precursor powder obtained in step (1) is placed in a graphite mold in air, and the graphite mold is placed in a spark plasma sintering furnace. Under a pressure of 30 MPa, the temperature is raised to 400° C. within 5 minutes, and then the temperature is raised to 450° C. within 2 minutes, and the spark plasma sintering is performed at 450° C. for 5 minutes; after the sintering is completed, the pressure is reduced to 0.05 MPa and the temperature is reduced to 440° C. within 2 minutes, and then the furnace is cooled to room temperature to obtain Ag. 1.01 Sb 0.9 Bi 0.09 Se2 thermoelectric material.

[0063] Example 2

[0064] This embodiment discloses a low thermal conductivity p-type AgSbSe2-based thermoelectric material, the chemical composition of which is Ag 1.02 Sb 0.89 Bi 0.09 Se2; the reaction raw materials are 5.5699g Ag metal particles, 5.4861g Sb metal particles, 0.9520g Bi metal particles, and 7.9922g Se metal particles, wherein the amount ratio of Ag metal particles, Sb metal particles, Bi metal particles, and Se metal particles is 1.02:0.89:0.09:2,

[0065] The preparation method is the same as that in Example 1.

[0066] Example 3

[0067] This embodiment discloses a low thermal conductivity p-type AgSbSe2-based thermoelectric material, the chemical composition of which is AgSb 0.97 Bi 0.03 Se2; the reaction raw materials are 5.5300g Ag metal particles, 6.0552g Sb metal particles, 0.3213g Bi metal particles, and 8.0936g Se metal particles, among which the molar ratio of Ag metal particles, Sb metal particles, Bi metal particles, and Se metal particles is 1:0.97:0.03:2.

[0068] The preparation method is the same as that in Example 1.

[0069] Example 4

[0070] This embodiment discloses a low thermal conductivity p-type AgSbSe2-based thermoelectric material, the chemical composition of which is AgSb 0.94 Bi 0.06 Se2; the reaction raw materials are 5.4932g Ag metal particles, 5.8288g Sb metal particles, 0.6384g Bi metal particles, and 8.0397g Se metal particles, wherein the molar ratio of the Ag metal particles, Sb metal particles, Bi metal particles, and Se metal particles is 1:0.94:0.06:2; the rest is the same as Example 1.

[0071] The preparation method is the same as that in Example 1.

[0072] Example 5

[0073] This embodiment discloses a low thermal conductivity p-type AgSbSe2-based thermoelectric material, the chemical composition of which is AgSb 0.91 Bi 0.09 Se2; the reaction raw materials are 5.4569g Ag metal particles, 5.6055g Sb metal particles, 0.9513g Bi metal particles, and 7.9866g Se metal particles, wherein the molar ratio of Ag metal particles, Sb metal particles, Bi metal particles, and Se metal particles is 1:0.91:0.09:2; the rest is the same as Example 1.

[0074] The preparation method is the same as that in Example 1.

[0075] Comparative Example 1

[0076] Comparative Example 1 discloses a p-type AgSbSe2-based thermoelectric material, which is basically the same as Example 1, except that: without doping with Bi and Ag, Sb cations, the chemical composition of the thermoelectric material is AgSbSe2; the reaction raw materials are 5.5674g Ag metal particles, 6.2846g Sb metal particles and 8.1483g Se metal particles, wherein the molar ratio of Ag metal particles, Sb metal particles and Se metal particles is 1:1:2.

[0077] The electrical performance test of the thermoelectric materials obtained in Examples 1 to 5 was carried out using the LSR-3 electrical performance test system. The test curve of the Seebeck coefficient is shown in FIG. Figure 1 As shown (wherein, the purple line is Example 1, the yellow line is Example 2, the red line is Example 3, the blue line is Example 4, the green line is Example 5, and the gray line is Comparative Example 1, Figure 1-6 The line colors all refer to the same), the conductivity test curve is as follows Figure 2 As shown, the test curve of power factor is as follows Figure 3 As shown. Figures 5-6 It can be seen that compared with the regulation of the content of Ag and Sb, the thermoelectric material obtained by the present invention has a higher power factor and a lower thermal conductivity.

[0078] The thermal diffusion coefficient F of the thermoelectric materials obtained in Examples 1 to 5 was tested by laser flash method (LFA-457 laser thermal conductivity meter), and the sample density Dd measured by Archimedes drainage method and the formula Cp [J g -1 K -1 ]=9n m k B (T / θ D )∫ θD / T x 4 e x / (e x -1) 2 dx calculated heat capacity Cp, and then calculate the total thermal conductivity κ according to the following formula: κ = CpDd, the result of total thermal conductivity is as follows Figure 4 As shown. Figure 4 It can be seen that as the Bi doping content increases, the thermal conductivity of the material decreases, and the thermal conductivity of the thermoelectric material obtained by the present invention is even lower at low temperatures.

[0079] Using κ l =κ-κe is used to calculate the lattice thermal conductivity of the thermoelectric materials obtained in Examples 1 to 5 and Comparative Example 1, and the results are as follows: Figure 5 As shown. Figure 5 It can be seen that compared with the case where Bi0.09 is doped and Ag 1.01 and Sb 0.9 are contained, the lattice thermal conductivity of the thermoelectric material obtained in the present invention is lower at low temperature.

[0080] Using the formula ZT=S 2 σT / κ tot The thermoelectric figures of merit of the thermoelectric materials obtained in Examples 1 to 5 and Comparative Example 1 were calculated, and the results are shown in Table 1.

[0081] The peak values ​​ZT of the thermoelectric materials prepared in Examples 1 to 5 and Comparative Example 1 at 673 K are shown in Table 1.

[0082] Table 1 Peak ZT of thermoelectric materials prepared in Examples 1 to 5 at 673K

[0083] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Peak ZT 1.11 0.81 0.34 0.3 0.7 0.31

[0084] from Figure 5 As can be seen from Table 1, the thermoelectric material after doping with Bi and adjusting the ratio of Ag and Sb elements has a higher thermoelectric figure of merit.

[0085] In summary, the p-type AgSbSe2-based thermoelectric material provided by the present invention has a higher Seebeck coefficient, electrical conductivity and lower lattice thermal conductivity, which ultimately improves its thermoelectric figure of merit.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low thermal conductivity p-type AgSbSe2-based thermoelectric material, characterized in that: The chemical composition is Ag 1+y Sb 1-x-y Bi x Se2, where 0<x≤0.09, 0.01≤y≤0.02, where x and y are the ratio of the amount of substance.

2. The low thermal conductivity p-type AgSbSe2-based thermoelectric material according to claim 1, characterized in that: The chemical composition is Ag 1+y Sb 1-x-y Bi x Se2, where x=0.09, 0.01≤y≤0.

02.

3. A method for preparing a p-type AgSbSe2-based thermoelectric material with low thermal conductivity according to claim 1 or 2, characterized in that: The following steps are involved: (1) Ag particles, Bi particles, Sb particles and Se particles are placed in a ratio of 3.8 to 4.5 × 10 -3 The sealed quartz tube is vacuum sealed under the pressure of 1.5 Pa, and the sealed quartz tube is placed in a muffle furnace, and the temperature is slowly increased from room temperature to 440-460°C for 12-14 hours, and then the temperature is increased to 850-900°C for 4-6 hours and kept at this temperature for 16-20 hours, and then cooled with the furnace to obtain a smelted alloy ingot; (2) Grinding the alloy ingot to obtain powder, and sintering the powder to obtain p-type AgSbSe2-based thermoelectric material.

4. The method for preparing the p-type AgSbSe2-based thermoelectric material with low thermal conductivity according to claim 3, characterized in that: The purity of the Ag particles, Bi particles, Sb particles and Se particles in step (1) is greater than or equal to 99.999%.

5. The method for preparing the p-type AgSbSe2-based thermoelectric material with low thermal conductivity according to claim 3, characterized in that: The vacuum degree in step (1) is 4.0 to 4.5×10 -3 Pa.

6. The method for preparing a p-type AgSbSe2-based thermoelectric material with low thermal conductivity according to claim 3, characterized in that: The powder particle size of step (2) is 200-300 mesh.

7. The method for preparing the low thermal conductivity p-type AgSbSe2-based thermoelectric material according to claim 3, characterized in that: The sintering in step (2) is spark plasma sintering.

8. The method for preparing the low thermal conductivity p-type AgSbSe2-based thermoelectric material according to claim 3 or 7, characterized in that: The sintering pressure in step (2) is 30-40 MPa, the sintering temperature is 400-450° C., and the sintering time is 1-10 min.

9. The method for preparing the low thermal conductivity p-type AgSbSe2-based thermoelectric material according to claim 3 or 7, characterized in that: The sintering temperature in step (2) is programmed heating: firstly, the temperature is raised to 400-420°C in 4-6 minutes, and then the temperature is raised to 440-450°C in 1-2 minutes, and then kept at this temperature for 3-5 minutes.

10. Use of the low thermal conductivity p-type AgSbSe2-based thermoelectric material according to claim 1 or 2 in the thermoelectric field.

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