Multiple CuI composite BiSbSe3-based thermoelectric material, and preparation method and application thereof

Abstract

The invention provides a multiple CuI composite BiSbSe3-based thermoelectric material and a preparation method and application thereof, the chemical composition of the multiple CuI composite BiSbSe3-based thermoelectric material is BiSbSe3 + x% mol CuI, and x is equal to 0.5-3. And the molar ratio of the decomposed CuI to the separated CuI in the multiple CuI composite BiSbSe3-based thermoelectric material is (10: 1)-(2: 1). The invention further discloses a preparation method and application of the multiple CuI composite BiSbSe3-based thermoelectric material. The multi-CuI composite BiSbSe3-based thermoelectric material disclosed by the invention has relatively low lattice thermal conductivity and relatively high electrical conductivity, and the thermoelectric figure of merit ZT of the multi-CuI composite BiSbSe3-based thermoelectric material is 0.3-0.6, that is, the multi-CuI composite BiSbSe3-based thermoelectric material disclosed by the invention has excellent thermoelectric performance, can realize coordinated regulation and control on electric transport performance and heat transport performance, and improves the thermoelectric figure of merit.

Description

Technical Field

[0001] The present invention relates to thermoelectric material technology, and in particular to a multi-CuI composite BiSbSe3-based thermoelectric material, a preparation method and use thereof. Background Art

[0002] Thermoelectric materials can directly convert heat into electrical energy, providing a new type of green energy that can alleviate the energy crisis. They have huge market potential and application prospects in the fields of temperature difference power generation and thermoelectric cooling. The performance of thermoelectric materials mainly depends on the 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. Therefore, an ideal thermoelectric material should have a high Seebeck coefficient, high electrical conductivity, and low thermal conductivity.

[0003] Currently, most thermoelectric materials, such as PbTe, GeTe, and Bi2Te3, show excellent thermoelectric properties. However, due to the low content of tellurium in the earth's crust, it is relatively expensive, which hinders its large-scale application and commercial development. As an approximate compound of commercial bismuth telluride, BiSbSe3, which does not contain Te, has shown great potential in medium and low temperature thermoelectric materials due to its low cost, high Seebeck coefficient, low thermal conductivity and easy preparation. However, BiSbSe3 is obtained by alloying Sb with topological insulator Bi2Se3, and has an extremely low carrier concentration, resulting in a ZT value close to zero, which limits its application in the field of thermoelectrics. Summary of the invention

[0004] The purpose of the present invention is to propose a multiple CuI composite BiSbSe3-based thermoelectric material to address the problem that the thermoelectric figure of merit ZT of existing BiSbSe3-based thermoelectric materials approaches zero. The thermoelectric material has lower lattice thermal conductivity and higher electrical conductivity, and its thermoelectric figure of merit ZT is 0.3-0.6. That is, the multiple CuI composite BiSbSe3-based thermoelectric material of the present invention has excellent thermoelectric properties, can achieve coordinated regulation of electrical transport performance and thermal transport performance, and improve the thermoelectric figure of merit.

[0005] 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.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a multi-CuI composite BiSbSe3-based thermoelectric material, whose chemical composition is BiSbSe3+x% molCuI, wherein x=0.5~3.

[0007] Furthermore, the x is 0.5, 1, 2 or 3.

[0008] Furthermore, the x is preferably 2-3.

[0009] Furthermore, the molar ratio of decomposed CuI to precipitated CuI in the multiple CuI composite BiSbSe3-based thermoelectric material is 10:1-2:1, and the preferred molar ratio is 5:1-2:1. CuI exhibits multiple functions in BiSbSe3, with a portion separated in the form of ions and a portion precipitated, which can achieve coordinated regulation of electrical and thermal transport properties, and ultimately significantly improve thermoelectric performance. Specifically, I - Can replace Se 2- , generating an extra electron. At the same time, Cu + It tends to occupy the van der Waals interstitial position, provide an electron, and form a conductive layer at the interstitial position to increase carrier mobility. The combination of this element substitution and interstitial copper optimizes the electrical properties and increases the power factor. In addition, through CuI composite, defects such as in-situ CuI precipitation, (Bi, Sb)SeI nanoprecipitation, Cu element grain boundary segregation, and dislocation are introduced. These multi-scale defects effectively scatter phonons of different frequencies and effectively reduce the lattice thermal conductivity. Therefore, by utilizing the multiple effects of CuI in BiSbSe3, the electrical and thermal transport properties of thermoelectric materials can be optimized simultaneously, significantly improving the thermoelectric figure of merit.

[0010] Furthermore, the multiple CuI composite BiSbSe3-based thermoelectric material is an n-type BiSbSe3-based thermoelectric material.

[0011] Furthermore, the lattice thermal conductivity of the multiple CuI composite BiSbSe3-based thermoelectric material is 0.2-0.6 Wm -1 K -1 , power factor is 1.5~3.5μWcm -1 K -2 , the thermoelectric figure of merit ZT is 0.3~0.6.

[0012] Another object of the present invention is to disclose a method for preparing a multi-CuI composite BiSbSe3-based thermoelectric material, comprising the following steps:

[0013] Step 1: In an inert gas atmosphere with a water and oxygen content of less than 1 ppm, a single substance of Bi, a single substance of Sb, a single substance of Se and CuI are mixed according to a predetermined stoichiometric amount to obtain a mixed powder;

[0014] Step 2, placing the mixed powder in a vacuum container and sealing it;

[0015] Step 3, placing the vacuum container containing the powder in a box furnace for smelting, and sequentially quenching and annealing the melt to obtain an ingot;

[0016] Step 4, grinding the ingot in an inert gas atmosphere with a water and oxygen content of less than 1 ppm to obtain a precursor powder;

[0017] Step 5: hot-press and sinter the precursor to prepare a multi-CuI composite BiSbSe3-based thermoelectric material.

[0018] Furthermore, the inert gas in step 1 and step 4 includes but is not limited to argon.

[0019] Furthermore, in step 1, the purity of the Bi single substance is greater than or equal to 99.999%; the purity of the Sb single substance is greater than or equal to 99.999%, the purity of the Se single substance is greater than or equal to 99.999%, and the purity of the CuI is greater than or equal to 99.95%; the Bi single substance, the Sb single substance, the Se single substance, and the CuI are used in powder form. The present invention mixes the raw material powders under an inert gas atmosphere to prevent the raw material powders from being oxidized.

[0020] Furthermore, the vacuum container in step 2 is a quartz tube; the diameter of the quartz tube is 10 to 40 mm, preferably 15 to 35 mm, and more preferably 20 to 30 mm.

[0021] Furthermore, the smelting in step 3 is vacuum smelting.

[0022] Furthermore, the vacuum degree of the vacuum container in step 3 is ≤5×10 -3 Pa. Preferably 5×10 -4 ~5×10 -3 Pa; more preferably 1×10 -3 ~5×10 -3 Pa.

[0023] Furthermore, in step 3, the vacuum container is placed in a box furnace for smelting, the smelting temperature is ≥900°C, and the holding time is 12 to 18 hours. The smelting temperature is preferably 900 to 930°C, more preferably 900 to 920°C, and most preferably 900 to 910°C; the holding time is preferably 14 to 18 hours, more preferably 16 to 18 hours, and most preferably 17 to 18 hours.

[0024] Furthermore, the quenching temperature in step 3 is 800-900° C., preferably 820-900° C., and more preferably 850-900° C.; the quenching medium includes liquid nitrogen or water, preferably water.

[0025] Furthermore, the annealing in step 3 is vacuum annealing; the vacuum degree of the vacuum annealing is ≤5×10 -3 Pa, preferably 5×10-4 ~5×10 -3 Pa, more preferably 1×10 -3 ~5×10 -3 Pa. In the present invention, the vacuum container used for annealing is preferably a quartz tube; the diameter of the quartz tube is preferably 10 to 40 mm, more preferably 15 to 35 mm, and most preferably 20 to 30 mm.

[0026] Furthermore, the annealing temperature in step 3 is 300-400° C., preferably 350-400° C., more preferably 380-400° C.; the annealing time is 24-48 h, preferably 30-48 h, more preferably 36-48 h.

[0027] Furthermore, the diameter of the precursor powder in step 4 is ≤180 μm, preferably ≤180 μm, more preferably ≤160 μm, and most preferably ≤150 μm.

[0028] Furthermore, the vacuum degree of the hot pressing sintering in step 5 is 0.01-1Pa, preferably 0.05-1Pa, and more preferably 0.1-0.5Pa; the sintering pressure is 30-50MPa, preferably 30-45MPa, and more preferably 40-45MPa; the sintering temperature is 380-430°C, preferably 390-420°C, and more preferably 400-410°C; the sintering time is 90-120min, preferably 100-120min, and more preferably 110-120min.

[0029] Furthermore, the hot pressing sintering in step 5 is performed in a graphite mold. The graphite mold is in the shape of a cylinder, and the inner diameter of the cylinder is 10 to 13 mm, preferably 11 to 13 mm, and more preferably 12 to 13 mm.

[0030] Another object of the present invention is to disclose the use of a multi-CuI composite BiSbSe3-based thermoelectric material in the field of medium and low temperature thermoelectric conversion devices.

[0031] The multiple CuI composite BiSbSe3-based thermoelectric material, preparation method and use thereof of the present invention have the following advantages compared with the prior art:

[0032] 1) The present invention discloses a multi-CuI composite BiSbSe3-based thermoelectric material, the chemical composition of which is BiSbSe3+x%CuI, wherein x=0.5-3. The present invention utilizes the multiple effects of CuI in BiSbSe3-based thermoelectric materials to coordinately regulate electrical and thermal properties, significantly improve electrical conductivity, and reduce thermal conductivity. On the one hand, CuI can be decomposed into Cu + and I - As carrier donors, Cu + ,I- They occupy the van der Waals interstitial positions and replace Se 2- , increasing the carrier concentration. In addition, Cu + A conductive layer is formed in the gap, which increases the carrier mobility and effectively improves the electrical transport performance. On the other hand, due to the recombination of CuI, multi-scale defects such as in-situ CuI precipitation, nano-precipitation phase, element segregation, and dislocation are introduced, which effectively enhances phonon scattering and reduces the phonon mean free path, resulting in ultra-low thermal conductivity. This is due to the trade-off between electrical and thermal properties.

[0033] 2) The thermoelectric figure of merit of the multi-CuI composite BiSbSe3-based thermoelectric material of the present invention is 0.3-0.6 (673K), for example, the maximum thermoelectric figure of merit of BiSbSe3+0.03CuI at 673K ​​is 0.6. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The power factor of the thermoelectric materials of Examples 1 to 4 and Comparative Examples 1 to 2 varies with temperature.

[0035] Figure 2 The lattice thermal conductivity of the thermoelectric materials of Examples 1 to 4 and Comparative Examples 1 to 2 varies with temperature.

[0036] Figure 3 The thermoelectric figure of merit diagrams of Examples 1 to 4 and Comparative Examples 1 to 2 are shown.

[0037] Figure 4 The fracture SEM images of Examples 1 to 4 and Comparative Example 1 and the SEM-EDS image of Example 4 are shown.

[0038] Among them, Figure (a) is comparative example 1, Figure (b) is embodiment 1, Figure (c) is embodiment 2, Figure (d) is embodiment 3, Figure (e) is embodiment 4, Figure (e1) is a partial enlarged view of embodiment 4, and Figures (e2)-(e6) are element distribution diagrams corresponding to (e1), which are Cu, I, Bi, Sb, and Se, respectively.

[0039] Figure 5 The electron probe microscopic analysis and corresponding element distribution diagram of Example 4. Figure (a) is the backscattered electron diagram of Example 4, and Figures (b)-(f) are the element distribution diagrams corresponding to Figure (a), which are Se, Sb, Bi, I, and Cu, respectively.

[0040] Figure 6 : It is a high-angle annular dark field image of Example 4. Among them, Figure (a) is a high-magnification HAADF-STEM image of Example 4, Figures (b) and (c) are enlarged images of area 1 in Figure (a), Figure (d) is an inverse Fourier transform image of Figure (a), and Figures (e) and (f) are images along ε xx and εyx Directional geometric phase analysis diagram.

[0041] Figure 7 It is a high-angle annular dark field image and the corresponding element distribution map of Example 4. Among them, Figure (a) is a low-magnification HAADF-STEM image, Figure (b) is an enlarged image of area 1 in Figure (a), Figures (b1)-(b5) are element distribution maps corresponding to Figure (b), which are Cu, I, Bi, Sb, and Se respectively, Figure (c) is an enlarged image of area 2 in Figure (a), Figures (c1)-(c5) are element distribution maps corresponding to Figure (c), which are Cu, I, Bi, Sb, and Se respectively, and Figure (d) is a high-magnification HAADF-STEM image of area 3 in Figure (b). DETAILED DESCRIPTION

[0042] 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:

[0043] 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.

[0044] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0045] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0046] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0047] 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.

[0048] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0049] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0050] Example 1

[0051] This embodiment discloses a multi-CuI composite BiSbSe3-based thermoelectric material, the chemical composition of which is BiSbSe3+0.5% molCuI.

[0052] The preparation method of the multi-CuI composite BiSbSe3-based thermoelectric material comprises the following steps:

[0053] According to the stoichiometric ratio, Bi, Sb, Se and CuI were weighed in an argon atmosphere with a water and oxygen content of less than 1 ppm, mixed in a high-temperature resistant quartz tube with a diameter of 20 mm, and sealed with a tube sealing machine (the vacuum degree in the quartz tube was ≤5×10 -3 Pa) to obtain a mixed powder. The sealed quartz tube is then placed in a box furnace for high-temperature melting at 900°C for 18 hours, followed by water quenching at 900°C, and then annealing at 400°C for 48 hours to obtain an ingot. The ingot is placed in an argon atmosphere with a water oxygen content of less than 1ppm and ground in a mortar to obtain a precursor powder with a powder diameter of ≤150μm. 20g of the precursor powder is loaded into a graphite mold with an inner cavity of 13mm in inner diameter and a graphite paper tube (thickness 0.1mm), and hot pressing sintering technology is used to form it. The sintering temperature is 400°C, the sintering pressure is 45MPa, and the insulation time is 120min to obtain the thermoelectric material BiSbSe3+0.5%molCuI.

[0054] Example 2

[0055] Example 2 discloses a multi-CuI composite BiSbSe3-based thermoelectric material, whose chemical composition is BiSbSe3+1% molCuI, and whose preparation method is the same as that of Example 1.

[0056] Example 3

[0057] Example 3 discloses a multi-CuI composite BiSbSe3-based thermoelectric material, whose chemical composition is BiSbSe3+2% molCuI, and whose preparation method is the same as that of Example 1.

[0058] Example 4

[0059] Example 4 discloses a multi-CuI composite BiSbSe3-based thermoelectric material, whose chemical composition is BiSbSe3+3% molCuI, and whose preparation method is the same as that of Example 1.

[0060] Comparative Example 1

[0061] Comparative Example 1 discloses a BiSbSe3-based thermoelectric material, the chemical composition of which is BiSbSe3. The difference from Example 1 is that CuI is not compounded, and the preparation method thereof is the same as that of Example 1.

[0062] Comparative Example 2

[0063] Comparative Example 2 discloses a Cu-composite BiSbSe3-based thermoelectric material, the chemical composition of which is BiSbSe3+3%wtCu.

[0064] The method for preparing the Cu composite BiSbSe3-based thermoelectric material comprises the following steps:

[0065] According to the stoichiometric ratio, Bi, Sb and Se were weighed in an argon atmosphere with a water and oxygen content of less than 1 ppm, mixed in a high-temperature resistant quartz tube with a diameter of 20 mm, and sealed with a tube sealing machine (the vacuum degree in the quartz tube was ≤5×10 -3 Pa) to obtain a mixed powder. The sealed quartz tube is then placed in a box furnace for high-temperature melting at 900°C for 18 hours, followed by water quenching at 900°C, and then annealing at 400°C for 48 hours to obtain an ingot. The ingot is placed in an argon atmosphere with a water and oxygen content of less than 1ppm and ground in a mortar to obtain a precursor powder with a powder diameter of ≤150μm. The precursor powder and Cu powder are weighed and mixed according to the stoichiometric ratio of BiSbSe3+3%wtCu, and 20g of the mixed powder is loaded into a graphite mold with an inner diameter of 13mm and an inner cavity sleeved with a graphite paper tube (thickness 0.1mm), and hot pressing sintering technology is used for molding, the sintering temperature is 400°C, the sintering pressure is 45MPa, and the insulation time is 120min to obtain the thermoelectric material BiSbSe3+3%wtCuI.

[0066] The BiSbSe3-based thermoelectric materials of the embodiment and the comparative example were tested respectively. The test results are shown in Figure 1-7 shown.

[0067] Figure 1 The power factor of the thermoelectric materials of Examples 1 to 4 and Comparative Examples 1 to 2 varies with temperature. The LSR-3 instrument system was used to test the differential voltage / temperature and four-probe technology in a He atmosphere at 323K to 673K. Figure 1 It can be seen that the power factors of Examples 1 to 4 are much higher than those of Comparative Examples 1 to 2, wherein the power factor increases from 0.41 μW cm-1 of Comparative Example 1 to 0.61 μW cm-2 at 673 K. -1 K -2 Increased to 3.5 μWcm in Example 4 -1 K -2 .

[0068] Figure 2 The lattice thermal conductivity of the thermoelectric materials of Examples 1 to 4 and Comparative Examples 1 to 2 varies with temperature. Figure 2 It can be seen that the lattice thermal conductivity of Examples 1 to 4 is less than that of Comparative Examples 1 to 2, wherein the lattice thermal conductivity of Comparative Example 1 at 673 K is 0.51 Wm -1 K -1 Reduced to 0.34Wm in Example 4 -1 K -1 .

[0069] Figure 3 The thermoelectric figure of merit diagrams of Examples 1 to 4 and Comparative Examples 1 to 2. The maximum thermoelectric figure of merit of Example 4 at 673K ​​is 0.6, which is 12 times higher than the thermoelectric figure of merit of 0.05 in Comparative Example 1.

[0070] Figure 4 The fracture SEM images of Examples 1 to 4 and Comparative Example 1 and the SEM-EDS image of Example 4 are shown.

[0071] Among them, Figure (a) is comparative example 1, Figure (b) is embodiment 1, Figure (c) is embodiment 2, Figure (d) is embodiment 3, and Figure (e) is embodiment 4. It can be seen from Figures (a)-(e) that the grains are lamellar, and after the composite CuI, the grain size is promoted, which helps to increase the carrier mobility. Figure (e1) is a partial enlarged view of embodiment 4, and Figures (e2)-(e6) are element distribution diagrams corresponding to (e1), which are Cu, I, Bi, Sb, and Se, respectively. There is obvious grain boundary segregation of Cu element and in-situ CuI precipitation, which plays an important role in phonon scattering.

[0072] Figure 5 The electron probe microscopic analysis and corresponding element distribution diagram of Example 4. Figure (a) is the backscattered electron diagram of Example 4, where dark CuI precipitation and linear element segregation can be observed. Figures (b)-(f) are the element distribution diagrams corresponding to Figure (a), which are Se, Sb, Bi, I, and Cu, respectively. Figure 5 It can be seen that in-situ CuI precipitation exists in Example 4, as shown in the yellow square marked areas in Figures (e) and (f), and there is Cu element segregation, as shown by the red arrow in Figure (f). Micron-scale CuI precipitation and Cu segregation can effectively scatter medium-frequency and low-frequency phonons and reduce lattice thermal conductivity.

[0073] Figure 6 It is a high-angle annular dark field image of Example 4. Figure (a) is a high-magnification HAADF-STEM image of Example 4. The electron diffraction spot analysis confirmed that the phase is BiSbSe3. Figure 6 (b) and (c) are enlarged views of region 1 in (a). It can be observed that Cu is inserted into the van der Waals gap, which not only provides additional electrons but also forms a conductive layer to improve carrier mobility. Figure (d) is the inverse Fourier transform of Figure (a), and Figures (e) and (f) are geometric phase analysis views of Figure (a). Figures (d), (e) and (f) reflect the dislocation and the ε-axis in Example 4, respectively. xx and ε yx From the strain in the direction, it can be observed that there are a large number of dislocations and strains in Example 4. These defects effectively scatter high-frequency phonons and contribute to the reduction of lattice thermal conductivity.

[0074] Figure 7 It is a high-angle annular dark field image and the corresponding element distribution map of Example 4. Figure (a) is a low-magnification HAADF-STEM image, and bright precipitates and element segregation are observed at the grain boundaries. Figure (b) is an enlarged image of area 1 in Figure (a), and Figures (b1)-(b5) are the element distribution maps corresponding to Figure (b), which are Cu, I, Bi, Sb, and Se, respectively. The bright precipitates are Bi-rich nano-precipitates through the element distribution map. Figure (c) is an enlarged image of area 2 in Figure (a), and Figures (c1)-(c5) are the element distribution maps corresponding to Figure (c), which are Cu, I, Bi, Sb, and Se, respectively. Analysis found that there is Bi and Cu element segregation, which is due to the low interface free energy and the tendency of atoms to move to the grain boundaries. Figure (d) is a high-magnification HAADF-STEM image of area 3 in Figure (b). Combined with the element distribution maps (Figures (b)-(b5)), it is determined that the Bi-rich nano-precipitation is (Bi, Sb)SeI. Nanoscale (Bi, Sb)SeI precipitation along the grain boundaries and element segregation effectively scatter mid-frequency and low-frequency phonons, reducing the phonon mean free path.

[0075] In summary, the CuI-composite BiSbSe3-based thermoelectric material provided by the present invention utilizes the multiple effects of CuI to improve the electrical transport performance while reducing the lattice thermal conductivity, ultimately improving its thermoelectric figure of merit.

[0076] 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 by 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 multi-CuI composite BiSbSe3-based thermoelectric material, characterized in that: Its chemical composition is BiSbSe3+x%molCuI, wherein x=0.5~3.

2. The multi-CuI composite BiSbSe3-based thermoelectric material according to claim 1, characterized in that: The molar ratio of decomposed CuI to precipitated CuI in the multiple CuI composite BiSbSe3-based thermoelectric material is 10:1 to 2:

1.

3. A method for preparing the multi-CuI composite BiSbSe3-based thermoelectric material according to claim 1 or 2, characterized in that: The following steps are involved: Step 1: In an inert gas atmosphere with a water and oxygen content of less than 1 ppm, a single substance of Bi, a single substance of Sb, a single substance of Se and CuI are mixed according to a predetermined stoichiometric amount to obtain a mixed powder; Step 2, placing the mixed powder in a vacuum container and sealing it; Step 3, placing the vacuum container containing the powder in a box furnace for smelting, and sequentially quenching and annealing the melt to obtain an ingot; Step 4, grinding the ingot in an inert gas atmosphere with a water and oxygen content of less than 1 ppm to obtain a precursor powder; Step 5: hot-press and sinter the precursor to prepare a multi-CuI composite BiSbSe3-based thermoelectric material.

4. The method for preparing the multi-CuI composite BiSbSe3-based thermoelectric material according to claim 3, characterized in that: The inert gas in step 1 and step 4 includes but is not limited to argon; And / or, the purity of the Bi element in step 1 is greater than or equal to 99.999%; the purity of the Sb element is greater than or equal to 99.999%, the purity of the Se element is greater than or equal to 99.999%, and the purity of the CuI element is greater than or equal to 99.95%; And / or, the Bi single substance, Sb single substance, Se single substance, and CuI are powders.

5. The method for preparing the multi-CuI composite BiSbSe3-based thermoelectric material according to claim 3, characterized in that: The vacuum container in step 2 is a quartz tube; the diameter of the quartz tube is 10 to 40 mm.

6. The method for preparing the multi-CuI composite BiSbSe3-based thermoelectric material according to claim 3, characterized in that: The smelting in step 3 is vacuum smelting; And / or, the vacuum degree of the vacuum container in step 3 is ≤5×10 -3 Pa; And / or, the vacuum container in step 3 is placed in a box furnace for smelting, the smelting temperature is ≥900° C., and the insulation time is 12 to 18 hours.

7. The method for preparing the multi-CuI composite BiSbSe3-based thermoelectric material according to claim 3, characterized in that: The quenching temperature in step 3 is 800-900° C. And / or, the quenching medium in step 3 includes liquid nitrogen or water; And / or, the annealing in step 3 is vacuum annealing; the vacuum degree of the vacuum annealing is ≤5×10 -3 Pa; And / or, the annealing temperature in step 3 is 300-400° C.; the annealing time is 24-48 hours.

8. The method for preparing the multi-CuI composite BiSbSe3-based thermoelectric material according to claim 3, characterized in that: The precursor powder in step 4 has a diameter of ≤180 μm.

9. The method for preparing the multi-CuI composite BiSbSe3-based thermoelectric material according to claim 3, characterized in that: Step 5: The vacuum degree of the hot pressing sintering is 0.3-10 Pa; the sintering temperature is 380-430° C.; and the sintering time is 90-120 min. And / or, the hot pressing sintering in step 5 is carried out in a graphite mold.

10. Use of the multiple CuI composite BiSbSe3-based thermoelectric material according to claim 1 or 2 in the field of medium and low temperature thermoelectric conversion devices.

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