Thermoelectric material, method of making the same, and thermoelectric device

Abstract

The application provides a thermoelectric material, a preparation method thereof and a thermoelectric device, and the chemical formula of the thermoelectric material is Sn (1‑x‑y) Cu x La y Se, wherein 0<=x<=0.2 and 0 The thermoelectric material provided by the application is doped with lanthanum (La) and / or copper (Cu) to effectively control the polycrystalline tin selenide lattice arrangement and macroscopically, so that the thermoelectric material has high hole carrier concentration and dense crystal defects, thereby improving the ZT value of the thermoelectric material Sn (1‑x‑y) Cu x La y Se, and further improving the thermoelectric conversion efficiency of the thermoelectric material. Meanwhile, the thermoelectric material has a wide temperature range, can effectively utilize heat energy exceeding 200 DEG C, and has good application prospect.

Description

Technical Field

[0001] This application relates to thermoelectric materials, and more particularly to a thermoelectric material, its preparation method, and a thermoelectric device. Background Technology

[0002] Thermoelectric materials are materials that can convert heat energy into electrical energy. Existing technologies typically use CoSb3 or YbTe3CoSb as thermoelectric materials. 12 YbFe 3.6 Ni 0.4 Sb 12 Materials such as BiTe are used in thermoelectric materials, which generally operate in the temperature range of room temperature to 200°C. They cannot effectively utilize heat energy exceeding 200°C. Summary of the Invention

[0003] The purpose of this application is to provide a thermoelectric material, its preparation method, and a thermoelectric device. This thermoelectric material has a wide operating temperature range and can effectively utilize thermal energy exceeding 200°C, showing good application prospects.

[0004] This application provides a thermoelectric material with the chemical formula Sn. (1-x-y) Cu x La y Se, where 0 ≤ x ≤ 0.2, 0 < y ≤ 0.18.

[0005] The thermoelectric material Sn provided in this application (1-x-y) Cu x La y Using lanthanum (La) and / or copper (Cu) to dope tin selenide (SnSe) allows for effective control over the lattice arrangement and macroscopic structure of polycrystalline tin selenide. On one hand, this results in a high hole carrier concentration in the thermoelectric material, facilitating a high power factor. On the other hand, doping with lanthanum (La) and / or copper (Cu) creates dense crystal defects in the thermoelectric material, leading to low thermal conductivity and thus improving the performance of the SnSe thermoelectric material. (1-x-y) Cu x La y The ZT value of Se is beneficial for improving the thermoelectric conversion efficiency of thermoelectric materials. Furthermore, when lanthanum (La) and copper (Cu) are doped simultaneously, they can produce a synergistic effect, resulting in thermoelectric materials with both high hole carrier concentration and dense crystal defects. This improves the power factor of the thermoelectric material while reducing its thermal conductivity, thereby enhancing its thermoelectric performance and ultimately improving its thermoelectric conversion efficiency. In addition, the thermoelectric material Sn... (1-x-y) Cu x La ySe also has a wide operating temperature range and can still effectively utilize heat energy exceeding 200℃, thus having a broader application prospect.

[0006] In one possible implementation, x > 0.

[0007] In one possible implementation, the thermoelectric material is a ribbon-like crystal.

[0008] In one possible implementation, the thermoelectric figure of merit ZT of the thermoelectric material at a temperature of 800K is ≥4.1.

[0009] This application also provides a method for preparing a thermoelectric material, wherein the thermoelectric material is the aforementioned thermoelectric material, comprising the following steps:

[0010] A soluble tin salt is added to a first solvent and mixed to obtain a tin salt solution. A first dopant is added to the tin salt solution and the pH of the solution is adjusted to 10-12 to obtain a first mixed solution.

[0011] A soluble selenium salt is added to a second solvent and mixed to obtain a selenium salt solution. A second dopant is added to the selenium salt solution and the pH of the solution is adjusted to 10-12 to obtain a second mixture.

[0012] The first and second mixtures are mixed and placed in a sealed environment and heated to 200°C–400°C for reaction.

[0013] The product obtained from the reaction is sintered;

[0014] The first dopant and the second dopant are selected from either a soluble lanthanum salt or a soluble copper salt, and the first dopant and the second dopant are different.

[0015] In one possible implementation, the first dopant is a soluble copper salt. The soluble copper salt is first added to the tin salt solution, and then a pH adjuster is added to adjust the pH of the solution to 10-12 to obtain the first mixture.

[0016] The second dopant is a soluble lanthanum salt. First, a pH adjuster is added to adjust the pH of the solution to 10-12, and then the soluble lanthanum salt is added to obtain the second mixture.

[0017] In one possible implementation, the pH adjuster is NaOH or KOH.

[0018] In one possible implementation, the sintering temperature range is 600°C to 700°C. By performing a sintering step on the product obtained from the reaction, the thermoelectric material can better exert its thermoelectric properties.

[0019] In one possible implementation, the sintering step specifically involves molding the product obtained from the reaction into a mold and then sintering it using spark plasma sintering technology.

[0020] This application also provides a thermoelectric device, including a wire and a thermoelectric body, the wire being connected to opposite ends of the thermoelectric body, and the thermoelectric body being made of the aforementioned thermoelectric material. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The graph shows the test results of the conductivity of the thermoelectric devices in Experiments 1 to 6 of this application;

[0023] Figure 2 The graph shows the test results of the Seebeck coefficient of the thermoelectric devices in Experiments 1 to 6 of this application;

[0024] Figure 3 The graph shows the test results of the thermal conductivity of the thermoelectric devices in Experiments 1 to 6 of this application;

[0025] Figure 4 The results are shown in the figure of merit of the thermoelectric devices in Experiments 1 to 6 of this application. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] This application provides a thermoelectric device, including a wire and a thermoelectric body. The wire is connected to opposite ends of the thermoelectric body, which is made of a thermoelectric material. The thermoelectric material exhibits a thermoelectric effect, converting heat energy into electrical energy. The thermoelectric device made from this material can introduce the potential difference generated by the thermoelectric effect into an external circuit to fully utilize heat energy. As an application example, the thermoelectric material provided in this application can be used to make a thermoelectric device and applied to an automotive exhaust emission system. The waste heat from the vehicle exhaust allows the thermoelectric device to generate electricity, recovering the heat energy of fossil fuels, thereby reducing fuel consumption and achieving energy conservation and emission reduction. It is understood that the thermoelectric device made from the thermoelectric material provided in this application can also be applied to other scenarios requiring the conversion of heat energy into electrical energy, and this application does not impose any limitations on this application.

[0028] Specifically, this application provides a thermoelectric material with the chemical formula Sn. (1-x-y) Cu x La y Se, where 0 ≤ x ≤ 0.2, 0 < y ≤ 0.18. The thermoelectric properties of thermoelectric materials are usually determined by the ZT value (thermoelectric figure of merit). Where ZT = S 2 Tσ / κ, S: Seebeck coefficient, T: absolute temperature, σ: electrical conductivity, κ: thermal conductivity, S is defined as follows: 2 σ: Power factor. Therefore, improving the ZT value of thermoelectric materials requires them to have a high power factor and low thermal conductivity.

[0029] The thermoelectric material Sn provided in this application (1-x-y) Cu x La y Using lanthanum (La) and / or copper (Cu) to dope tin selenide (SnSe) allows for effective control over the lattice arrangement and macroscopic structure of polycrystalline tin selenide. On one hand, this results in a high hole carrier concentration in the thermoelectric material, facilitating a high power factor. On the other hand, doping with lanthanum (La) and / or copper (Cu) creates dense crystal defects in the thermoelectric material, leading to low thermal conductivity and thus improving the performance of the SnSe thermoelectric material. (1-x-y) Cu x La y The ZT value of Se is beneficial for improving the thermoelectric conversion efficiency of thermoelectric materials. Furthermore, when lanthanum (La) and copper (Cu) are doped simultaneously, they can produce a synergistic effect, resulting in thermoelectric materials with both high hole carrier concentration and dense crystal defects. This improves the power factor of the thermoelectric material while reducing its thermal conductivity, thereby enhancing its thermoelectric performance and ultimately improving its thermoelectric conversion efficiency.

[0030] In addition, thermoelectric material Sn (1-x-y) Cux La y Se also has a wide operating temperature range, and can still effectively utilize heat energy exceeding 200°C. For example, Sn... (1-x-y) Cu x La y The operating temperature range for Se is room temperature to 550℃, i.e., Sn (1-x-y) Cu x La y Se retains high thermoelectric properties when used in a temperature range of room temperature to 550℃. (This is a description of the thermoelectric material Sn.) (1-x-y) Cu x La y The application temperature range of Se is widened, and the thermoelectric conversion efficiency is improved. For example, when applied to automotive exhaust systems, the temperature range of automotive exhaust gases is from room temperature to 500°C, due to the thermoelectric properties of Sn... (1-x-y) Cu x La y Se can operate in a temperature range of room temperature to 550°C, thus effectively utilizing the heat energy in vehicle exhaust to generate electricity, thereby reducing the overall fuel consumption of the vehicle.

[0031] This application also provides a method for preparing the above-mentioned thermoelectric material, comprising the following steps:

[0032] A soluble tin salt is added to a first solvent and mixed to obtain a tin salt solution. A first dopant is added to the tin salt solution and the pH of the solution is adjusted to 10-12 to obtain a first mixed solution.

[0033] A soluble selenium salt is added to a second solvent and mixed to obtain a selenium salt solution. A second dopant is added to the selenium salt solution and the pH of the solution is adjusted to 10-12 to obtain a second mixture.

[0034] The first and second mixtures are mixed and placed in a sealed environment and heated to 200°C–400°C for reaction.

[0035] The first dopant and the second dopant are selected from either a soluble lanthanum salt or a soluble copper salt, and the first dopant and the second dopant are different.

[0036] In this embodiment, the first dopant is a soluble copper salt. The soluble copper salt is first added to a tin salt solution, and then a pH adjuster is added to adjust the pH of the solution to 10-12, resulting in a first mixture. At this point, the tin and copper salts in the first mixture are only mixed and do not react. The soluble tin salt can be SnCl2·2H2O. The first solvent can be anhydrous ethylene glycol, anhydrous ethanol, or anhydrous propylene glycol. The soluble copper salt can be CuCl2. The pH adjuster can be NaOH or KOH. The pH adjuster ensures that the pH of the first mixture is 10-12, creating a suitable chemical environment for the subsequent reaction between the first and second mixtures. The first mixture can be stored at 5℃-20℃ to prevent the reduction of divalent copper.

[0037] In this embodiment, the second dopant is a soluble lanthanum salt. A pH adjuster is first added to adjust the pH of the solution to 10-12, and then the soluble lanthanum salt is added to obtain a second mixture. At this point, the selenium salt and lanthanum salt in the second mixture are only mixed and do not react. The soluble selenium salt can be a selenite. For example, the soluble selenium salt is Na₂SeO₃. The second solvent can be anhydrous ethylene glycol, anhydrous ethanol, or anhydrous propylene glycol. The soluble lanthanum salt can be LaCl₃. The pH adjuster can be NaOH or KOH. The pH adjuster ensures that the pH of the second mixture is 10-12, creating a suitable chemical environment for the subsequent reaction between the first and second mixtures.

[0038] The thermoelectric material Sn provided in this application (1-x-y) Cu x La y In the preparation method of Se, a solvothermal method is used. Lanthanum and copper are doped into the p-type tin selenide during the preparation process, resulting in a thermoelectric material, Sn. (1-x-y) Cu x La y Se exists as micron-sized ribbon-like crystals and also possesses excellent thermoelectric properties and high thermoelectric conversion efficiency.

[0039] The following describes the thermoelectric material Sn with specific experimental details. (1-x-y) Cu x La y The thermoelectric properties of Se, wherein the raw materials used in the following experiments are SnCl2·2H2O (purity 99.99%), Na2SeO3 (purity 99.99%), CuCl2 (purity 99.99%), LaCl3 (purity 99.99%), anhydrous ethylene glycol (purity 99.8%) and NaOH (purity 99.99%).

[0040] Experiment 1

[0041] Experiment 1 provides a thermoelectric device made of thermoelectric material Sn 0.977 Cu0.025 La 0.0018 Se is prepared according to the following steps:

[0042] Step S1: Add 100g of analytical grade SnCl2·2H2O(s) to 500mL of anhydrous ethylene glycol. Stir magnetically at room temperature for 20min to obtain a tin salt solution. After confirming that SnCl2·2H2O has completely dissolved, add 1.5g of analytical grade CuCl2 to the tin salt solution and stir magnetically for 30min until the CuCl2 is completely dissolved. Add a small amount of anhydrous ethylene glycol solution of NaOH(s) to adjust the pH of the solution to 10⁻¹² to obtain the first mixture. Place the obtained first mixture in an environment of 5℃~20℃ to prevent the reduction of divalent copper.

[0043] In step S2, 76.9 g of analytical grade Na₂SeO₃ was added to 200 mL of anhydrous ethylene glycol. The mixture was magnetically stirred for 20 min to fully dissolve the Na₂SeO₃ and obtain a selenium salt solution. Then, a small amount of anhydrous ethylene glycol solution of NaOH(s) was added to adjust the pH of the solution to 10–12. After the pH environment of the solution was adjusted, 0.2 g of analytical grade LaCl₃ was added to the solution, and the mixture was magnetically stirred for 10 h to obtain a second mixture.

[0044] Step S3: Take the first mixture obtained in step S1 and the second mixture obtained in step S2 and seal them into a 1000 mL stainless steel high-pressure reactor with a polytetrafluoroethylene liner. Place it at 250°C for 36 h and then cool it to room temperature.

[0045] After the reaction in step S3 is complete, the product obtained is filtered and washed repeatedly with anhydrous ethylene glycol until the washing solution is neutral. Finally, the washed product is vacuum dried at 80°C for 8 hours.

[0046] Step S5: Take the washed reaction product and press it into a cylindrical block with Φ = 15.0 mm and h = 10.0 mm by isostatic pressing. Then, sinter it for 10 min by spark plasma sintering (SPS) at 900 K (about 627 °C) and 60 MPa.

[0047] The material sintered in step S5 is processed into a cylindrical block with dimensions Φ = 12.0 mm and h = 8.0 mm using material cutting and polishing equipment. A wire circuit is then connected to the cylindrical block to obtain the thermoelectric device.

[0048] Experiment 2

[0049] Experiment 2 provides a thermoelectric device made of thermoelectric material Sn 0.977 La 0.023 Se was used to prepare the product, and the preparation steps were the same as in Experiment 1, except that CuCl2 was not added in step S1.

[0050] Experiment 3

[0051] Experiment 3 provides a thermoelectric device made of thermoelectric material Sn 0.977 Cu 0.023 Se was used to prepare the product, and the preparation steps were the same as in Experiment 1, except that LaCl3 was not added in step S2.

[0052] Experiment 4

[0053] Experiment 4 provides a thermoelectric device made of the thermoelectric material SnSe. The preparation steps are the same as those in Experiment 1, except that CuCl2 is not added in step S1 and LaCl3 is not added in step S2.

[0054] Experiment 5

[0055] Experiment 5 provides a thermoelectric device made of thermoelectric material Sn. 0.7732 Cu 0.225 La 0.0018 Se was used to prepare CuCl2, and the preparation steps were the same as in Experiment 1, except that the amount of CuCl2 added in step S1 was 13.3 g (approximately 0.1 mol).

[0056] Experiment 6

[0057] Experiment 6 provides a thermoelectric device made of thermoelectric material Sn 0.755 Cu 0.025 La 0.22 Se was used to prepare the product, and the preparation steps were the same as in Experiment 1, except that the amount of LaCl3 added in step S1 was 24.3 g (approximately 0.099 mol).

[0058] The thermoelectric devices obtained from Experiments 1 to 6 were subjected to thermoelectric performance tests, including electrical conductivity, Seebeck coefficient, and thermal conductivity. The test procedures and results are as follows:

[0059] 1. Conductivity and Seebeck coefficient test

[0060] The conductivity and Seebeck coefficient of the thermoelectric devices in Experiments 1 through 6 were tested in the range of 300K to 800K using a ZEM-3 thermoelectric performance testing system manufactured by Nippon Vacuum Technology Co., Ltd. The conductivity of the thermoelectric devices in Experiments 1 through 6 was measured using the standard four-probe method. This method involves using each thermoelectric device as a sample, passing a constant current through the sample, and measuring the voltage across the sample to obtain its resistance value. The resistivity or conductivity was then calculated based on the sample dimensions. The experimental results are shown below. Figure 1As shown. By establishing a small temperature difference ΔT (typically 3K-5K) inside the sample, the thermoelectric potential ΔV generated by this temperature gradient is measured. The Seebeck coefficient of the sample can be calculated using the slope relationship between ΔV and ΔT. The experimental results are shown in the figure. Figure 2 As shown.

[0061] from Figure 1 It can be seen that the undoped thermoelectric device in Experiment 4 has a low conductivity. Comparing Experiments 2, 3, and 4, the thermoelectric device doped with lanthanum (La) in Experiment 2 showed improved conductivity, and its conductivity was also improved compared to the thermoelectric device doped with copper in Experiment 3. Comparing Experiments 1 to 4, at the same temperature, the thermoelectric device in Experiment 1 was doped with both lanthanum (La) and copper. This combined doping of the two elements further improved the conductivity of the material, showing an increase compared to the thermoelectric device doped with lanthanum (La) alone in Experiment 2 and the thermoelectric device doped with copper alone in Experiment 3. Furthermore, comparing Experiments 1 to 6, at temperatures below 550K, the conductivity of the thermoelectric devices in Experiments 5 and 6 was improved compared to the thermoelectric device in Experiment 4, but decreased compared to the thermoelectric devices in Experiments 1 to 3. Experimental results show that doping with lanthanum (La) or copper can improve the electrical conductivity of the material, but when the doping levels of lanthanum (La) and copper exceed a certain amount, it is not conducive to further improving the electrical conductivity of the thermoelectric material Sn. (1-x-y) Cu x La y The electrical conductivity of thermoelectric devices made of Se.

[0062] from Figure 2 It can be seen that the thermoelectric device in Experiment 4, which is not doped with lanthanum (La) or copper, has a low Seebeck coefficient. The Seebeck coefficients of the thermoelectric devices in Experiment 1 (doped with both lanthanum (La) and copper), Experiment 2 (doped with only lanthanum (La), and Experiment 3 (doped with only copper) all showed improvement. Furthermore, the Seebeck coefficient improvement of the thermoelectric device in Experiment 2 was greater than that of the thermoelectric device in Experiment 3 (doped only copper). In addition, the Seebeck coefficients of the thermoelectric devices in Experiments 5 and 6 did not show a significant improvement compared to those in Experiment 4.

[0063] Furthermore, according to the definition of S 2σ: Power factor calculation. The power factor of the thermoelectric devices in Experiments 1 through 6, where S is the Seebeck coefficient and σ is the conductivity. Compared to the power factor of the thermoelectric device in Experiment 3 doped only with copper, the thermoelectric device in Experiment 2 doped with lanthanum (La) has a higher power factor, indicating that lanthanum (La) doping can effectively improve the power factor of thermoelectric materials, thus contributing to an increase in the ZT value. Furthermore, compared to the power factors of the thermoelectric devices in Experiments 2 and 3, the simultaneous doping of lanthanum (La) and copper in the thermoelectric device of Experiment 1 produces a synergistic effect, effectively improving the power factor of the thermoelectric device.

[0064] 2. Thermal conductivity test

[0065] Using the thermoelectric devices from Experiments 1 to 6 as samples, the thermal conductivity of the samples in the range of 300–800 K was calculated using the following formula: κ = DC p d. Wherein, D is the thermal diffusivity of the sample material, measured using the Laser Flash Method on an LFA-457 laser thermal conductivity meter manufactured by Netzsch GmbH, Germany. C p ρ is the isobaric heat capacity of the sample material, measured using a Q20 Differential Scanning Calorimeter (DSC) manufactured by TA Instruments, USA. d is the density of the sample material, obtained by Archimedes' displacement method. The thermal conductivity results of the thermoelectric devices in Experiments 1 to 6 are as follows: Figure 3 As shown.

[0066] from Figure 3 It can be seen that, by comparing experiments 1 to 4, the thermal conductivity of the thermoelectric devices in experiments 1 to 3 is lower than that of the undoped thermoelectric device in experiment 4. Meanwhile, the thermoelectric device in experiment 1, which is doped with both lanthanum (La) and copper, significantly reduces the thermal conductivity of the material compared to the undoped thermoelectric device in experiment 4 within the temperature range of 700K to 800K. Moreover, this reduction is more effective than the reduction in thermal conductivity achieved by the thermoelectric device in experiment 3 (doped with copper alone) or experiment 2 (doped with lanthanum alone), thus contributing to an increase in the ZT value of the thermoelectric material. Furthermore, in experiment 5, the reduction in thermal conductivity is not significant when the copper doping exceeds a certain content, while in experiment 6, the reduction in thermal conductivity is not only ineffective when the lanthanum (La) doping exceeds a certain content, but also results in a significant increase in the material's thermal conductivity.

[0067] Furthermore, according to the formula for the ZT value (thermoelectric figure of merit), ZT = S 2 Tσ / κ, and based on Figures 1 to 3 The thermoelectric figure of merit of the thermoelectric devices in Experiments 1 to 6 was calculated based on the data, and the results are as follows: Figure 4 As shown.

[0068] from Figure 4 As can be seen, both the thermoelectric devices in Experiment 1 and Experiment 2 exhibit high thermoelectric figures of merit in the range of 500K to 800K (approximately 228℃ to 528℃). Furthermore, the thermoelectric figures of merit ZT for both devices at 800K are ≥4.1. The experimental results demonstrate that the thermoelectric material Sn provided in this application… (1-x-y) Cu x La y Thermoelectric devices made with selenium (Se) exhibit a wide operating temperature range and can effectively utilize heat energy exceeding 200°C. Furthermore, compared to the undoped thermoelectric device in Experiment 4, the thermoelectric figure of merit (PGM) of the thermoelectric device in Experiment 2, through lanthanum doping, was improved. This is likely because lanthanum doping causes lattice contraction in the thermoelectric material, introducing nanoscale stress regions and causing local lattice distortion. Lanthanum doping achieves high hole carrier concentration, lattice distortion, dislocations, microcrystalline bending, and a significantly increased grain boundary density. These crystal defects effectively scatter phonons of different frequencies, thereby effectively reducing thermal conductivity and thus improving the material's PGM. Comparing Experiments 2 and 3, the PGM of the thermoelectric device in Experiment 2 is higher than that in Experiment 3, indicating that lanthanum (La) doping is more effective than copper doping. However, comparing Experiments 5 and 2, the PGM of the thermoelectric device in Experiment 5 decreased after exceeding a certain amount of lanthanum (La) doping. After extensive experimental testing, the thermoelectric material Sn (1-x-y) Cu x La y In Se, when the doping amount y of lanthanum (La) satisfies 0 < y ≤ 0.18, the thermoelectric material exhibits a high thermoelectric figure of merit (PhEP) and high thermoelectric conversion efficiency at 400℃–500℃. Comparing Experiment 6 and Experiment 3, in Experiment 6, after the copper doping amount exceeded a certain level, the PhEP of the thermoelectric device decreased significantly, even lower than that of the undoped thermoelectric device in Experiment 4. Extensive experimental testing has shown that the thermoelectric material Sn… (1-x-y) Cu x La y When the amount of copper doping x in Se satisfies 0 < x ≤ 0.2, the thermoelectric material has a high thermoelectric figure of merit and can have a high thermoelectric conversion efficiency at 400℃ to 500℃.

[0069] Furthermore, the thermoelectric figure of merit (PGM) of the thermoelectric device in Experiment 1 was higher than that of the thermoelectric device in Experiment 2 that was doped with lanthanum (La) alone and the thermoelectric device in Experiment 3 that was doped with copper alone. Experiment 1, through the combined doping of lanthanum (La) and copper, was able to further improve the PGM of the thermoelectric device. The experimental results show that the simultaneous doping of lanthanum (La) and copper can have a synergistic effect, effectively improving the PGM of the thermoelectric material, thereby helping to improve the thermoelectric conversion efficiency of the thermoelectric material.

[0070] The above-disclosed embodiments are merely preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art will understand that all or part of the processes for implementing the above embodiments and equivalent variations made in accordance with the claims of this application are still within the scope of this application.

Claims

1. A thermoelectric material, characterized in that, The chemical formula of the thermoelectric material is Sn. （1-x-y） Cu x La y Se, where 0 < x ≤ 0.2, 0 < y ≤ 0.

18.

2. The thermoelectric material according to claim 1, characterized in that, The thermoelectric material is a ribbon-shaped crystal.

3. The thermoelectric material according to any one of claims 1 to 2, characterized in that, The thermoelectric figure of merit ZT of the thermoelectric material is ≥4.1 at 800K.

4. A method for preparing a thermoelectric material, characterized in that, The thermoelectric material is the thermoelectric material according to any one of claims 1 to 3, and includes the following steps: A soluble tin salt is added to a first solvent and mixed to obtain a tin salt solution. A first dopant is added to the tin salt solution and the pH of the solution is adjusted to 10-12 to obtain a first mixed solution. A soluble selenium salt is added to a second solvent and mixed to obtain a selenium salt solution. A second dopant is added to the selenium salt solution and the pH of the solution is adjusted to 10-12 to obtain a second mixture. The first mixture and the second mixture are mixed and placed in a sealed environment and heated to 200°C~400°C for reaction; The product obtained from the reaction is sintered; The first dopant and the second dopant are selected from either a soluble lanthanum salt or a soluble copper salt, and the first dopant and the second dopant are different.

5. The method for preparing the thermoelectric material according to claim 4, characterized in that, The first dopant is a soluble copper salt. The soluble copper salt is first added to the tin salt solution, and then a pH adjuster is added to adjust the pH of the solution to 10-12 to obtain the first mixture. The second dopant is a soluble lanthanum salt. A pH adjuster is first added to adjust the pH of the solution to 10-12, and then the soluble lanthanum salt is added to obtain the second mixture.

6. The method for preparing the thermoelectric material according to claim 5, characterized in that, The pH adjuster is NaOH or KOH.

7. The method for preparing the thermoelectric material according to claim 4, characterized in that, The sintering temperature range is 600℃~700℃.

8. The method for preparing the thermoelectric material according to any one of claims 4 to 7, characterized in that, The sintering step specifically involves molding the product obtained from the reaction into a mold and then sintering it using spark plasma sintering technology.

9. A thermoelectric device, characterized in that, It includes a conductor and a thermoelectric body, the conductor being connected to opposite ends of the thermoelectric body, the thermoelectric body being made of the thermoelectric material according to any one of claims 1 to 3.

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