Tin telluride-based thermoelectric material with low lattice thermal conductivity and preparation method thereof

Abstract

The invention discloses a tin telluride-based thermoelectric material with low lattice thermal conductivity and a preparation method thereof, the tin telluride-based thermoelectric material with low lattice thermal conductivity has a chemical formula of Sn < 0.88 > Sb < 0.04 > Mn < 0.08 > Ge < 0.05 > Te-x% Cu < 2 > Te, and x < = 7. The preparation method comprises the following steps: weighing raw materials Sn, Te, Sb, Mn, Ge and Cu according to stoichiometry; the raw materials are transferred into a quartz tube after being mixed, vacuumized and sealed by oxyhydrogen flame; heating a quartz tube filled with the mixture, carrying out a melting reaction, and quenching in water after the reaction is finished to obtain a SnTe cast ingot; the SnTe cast ingot is ground into powder, the powder is put into a mold to be sintered, and the tin telluride-based thermoelectric material with the low lattice thermal conductivity is obtained. Non-toxic raw materials are adopted, the environmental protection property of the tin telluride-based thermoelectric material is guaranteed, meanwhile, a nano core-shell structure is formed in tin telluride through multi-element regulation and control doping and a proper process, and phonon scattering is greatly enhanced.

Description

Technical Field

[0001] This invention pertains to thermoelectric materials and their preparation methods, specifically a tin telluride-based thermoelectric material with low lattice thermal conductivity and its preparation method. Background Technology

[0002] Developing clean and renewable energy has become a major approach to solving the energy crisis and environmental pollution problems of the 21st century. In traditional thermal power plants, approximately 60% of the energy generated from the combustion of non-renewable fossil fuels is lost as waste heat, significantly reducing energy efficiency and increasing carbon emissions. Therefore, effectively recovering this underutilized waste heat and converting it into pollution-free renewable energy has enormous economic and ecological value. Thermoelectric conversion technology can directly convert waste heat into electricity, thereby achieving waste heat reuse and secondary power generation. It achieves higher power generation efficiency with low coal consumption. Moreover, thermoelectric systems have advantages such as being pollution-free, noise-free, highly reliable, and compact. Therefore, thermoelectric technology has enormous potential value in many fields, such as space power, electronic device power, and local temperature control and refrigeration.

[0003] Lead telluride, a typical thermoelectric material, has been the primary working medium for the radioisotope thermoelectric generators of the Voyager spacecraft since the 1970s. However, lead is highly toxic, and its extensive use would severely damage human health and pollute the environment. Therefore, tin telluride, a green and environmentally friendly material with a similar crystal structure to lead telluride, has become the most promising medium-temperature thermoelectric material. The energy conversion efficiency of tin telluride thermoelectric materials is mainly measured by the thermoelectric figure of merit ZT, where ZT = S. 2 σT / κ (where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity), where κ = κ l +κ e (κ) l κ is the lattice thermal conductivity. e (Electronic thermal conductivity) Since the Seebeck coefficient, electrical conductivity, and electronic thermal conductivity are strongly coupled with carrier concentration, optimizing one often worsens the other thermoelectric factor. In contrast, lattice thermal conductivity is an independent factor. Therefore, suppressing lattice thermal conductivity is an effective method to improve the thermoelectric performance of tin telluride. Most existing technologies reduce lattice thermal conductivity by increasing phonon scattering through point, line, and surface defects and porous structures, but the efficiency is often low, which limits the thermoelectric performance of tin telluride. There is an urgent need to explore new nanostructures to achieve ultra-low lattice thermal conductivity in tin telluride. Summary of the Invention

[0004] Purpose of the invention: In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a low-lattice thermal conductivity tin telluride-based thermoelectric material with good heat transfer properties and improved thermoelectric figure of merit. Another purpose of this invention is to provide an environmentally friendly method for preparing a low-lattice thermal conductivity tin telluride-based thermoelectric material.

[0005] Technical solution: The present invention relates to a low-lattice thermal conductivity tin telluride-based thermoelectric material with the chemical formula Sn. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-x%Cu2Te, where 0 <x≤7。

[0006] Furthermore, its chemical formula is Sn. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-3%Cu2Te, Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-5%Cu2Te, Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-6%Cu2Te or Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-7%Cu2Te.

[0007] The method for preparing the low-lattice thermal conductivity tin telluride-based thermoelectric material of the present invention includes the following steps:

[0008] Step 1: Weigh the raw materials Sn, Te, Sb, Mn, Ge, and Cu according to stoichiometry;

[0009] Step 2: After mixing the raw materials, transfer them to a quartz tube, evacuate the vacuum, and seal the tube with an oxyhydrogen flame.

[0010] Step 3: Heat the quartz tube containing the mixture to carry out the melting reaction. After the reaction is completed, quench the mixture in water to obtain SnTe ingots.

[0011] Step four: Grind the SnTe ingot into powder, put it into a mold and sinter it to obtain a tin telluride-based thermoelectric material with low lattice thermal conductivity.

[0012] Furthermore, in step one, the molar ratio of Sn, Te, Sb, Mn, Ge, and Cu is 0.88:0.04:0.08:0.05:0.06~0.14:1.03~1.07.

[0013] Furthermore, in step two, the vacuum level inside the quartz tube is less than 10 after evacuation. -2 Pa, preferably 5 × 10 -3 Pa.

[0014] Further, in step three, the heating process involves raising the temperature from room temperature to 950-1100 °C over 12-20 hours, and then holding the temperature at this level for 6-18 hours. Preferably, the heating process involves raising the temperature from room temperature to 1000 °C over 16 hours, and then holding the temperature at this level for 12 hours.

[0015] Furthermore, in step three, quenching is performed in water at 10~40 ℃, preferably 20 ℃.

[0016] Furthermore, in step four, the grinding time is 20-120 min, preferably 40 min.

[0017] Further, in step four, sintering involves heating to 500-600 °C at a heating rate of 50-100 °C / min and holding at that temperature for 5-30 min. Preferably, the temperature is heated to 600 °C at a heating rate of 75 °C / min and held for 5 min.

[0018] Furthermore, in step four, the sintering pressure is 30~60 MPa, preferably 40 MPa.

[0019] Preparation principle: Band structure optimization is achieved through composition design, uniform phase formation and initial defect introduction are achieved through vacuum melting and quenching, and high-pressure rapid sintering is combined to achieve structural densification and in-situ construction of coherent nanophases. Finally, through the synergistic effect of multi-scale defects, the electrical and thermal properties of the material are synergistically optimized, and high-performance SnTe-based thermoelectric materials with low lattice thermal conductivity are prepared.

[0020] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0021] 1. Using non-toxic Sn, Te, Sb, Mn, Ge and Cu as raw materials ensures the environmental friendliness of tin telluride-based thermoelectric materials. At the same time, through multi-element controlled doping and appropriate processes, a nano core-shell structure is formed in tin telluride, which greatly enhances phonon scattering.

[0022] 2. Preparation of Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-5%Cu2Te material at 600 o The lattice thermal conductivity of C is 0.21 W / m. -1 K -1 This is lower than the amorphous limit of SnTe (~0.4 W / m). -1 K -1 ), with a thermoelectric figure of merit as high as 1.5. Attached Figure Description

[0023] Figure 1 The X-ray diffraction patterns are those of the materials obtained in this invention and Comparative Example 1.

[0024] Figure 2 The graph shows the test results of the conductivity of the materials obtained in this invention and Comparative Example 1 as a function of temperature.

[0025] Figure 3 The graph shows the test results of the Seebeck coefficient of the materials obtained in this invention and Comparative Example 1 as a function of temperature.

[0026] Figure 4 The graph shows the test results of the power factor of the materials obtained in this invention and Comparative Example 1 as a function of temperature.

[0027] Figure 5 The graph shows the test results of the thermal conductivity of the materials obtained in this invention and Comparative Example 1 as a function of temperature.

[0028] Figure 6 The graph shows the test results of the lattice thermal conductivity of the materials obtained in this invention and Comparative Example 1 as a function of temperature.

[0029] Figure 7 The graph shows the test results of the thermoelectric figure of merit as a function of temperature for the materials obtained in this invention and Comparative Example 1.

[0030] Figure 8 The images shown are electron microscope images and energy dispersive spectra of the materials obtained in this invention and Comparative Example 1, wherein (a) is an electron microscope image and (b) is an energy dispersive spectrum. Detailed Implementation

[0031] Unless otherwise specified, all materials and reagents used in the following examples are commercially available. Experimental methods not specifically described in the examples are generally performed under standard conditions or as recommended by the manufacturer. All Sn, Te, Sb, Mn, Ge, and Cu raw materials are commercially available, with a purity greater than 99.9% and a particle size less than 100 mesh.

[0032] Example 1

[0033] A low-lattice thermal conductivity tin telluride-based thermoelectric material Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The preparation method of Te-3%Cu2Te includes the following steps:

[0034] (1) Weigh accurately according to the molar ratio of Sn, Sb, Mn, Ge, Cu and Te of 0.88:0.04:0.08:0.05:0.06:1.03.

[0035] (2) After mixing the above raw materials, place them in a quartz tube and evacuate to a vacuum degree of 5×10. -3 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0036] (3) The sealed quartz tube was placed in a muffle furnace for melting reaction. The temperature control program was set as follows: the temperature was increased from room temperature to 1000 °C in 16 hours, and held at this temperature for 12 hours. After the reaction was completed, the temperature was increased to 20 °C. Sn was obtained by quenching in water at ℃ 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-3%Cu2Te compound ingot.

[0037] (4) Grind the ingot obtained from the above reaction in a mortar for 40 minutes to obtain powder material; load it into a graphite mold and perform discharge plasma sintering. The sintering process conditions are: 75 o Rapidly increase the temperature to 600°C / min. o C, hold at this temperature for 5 minutes, then slowly cool to room temperature. The sintering pressure is 40 MPa. After sintering, Sn is obtained. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-3%Cu2Te columnar thermoelectric material.

[0038] Example 2

[0039] A low-lattice thermal conductivity tin telluride-based thermoelectric material Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The preparation method of Te-5%Cu2Te includes the following steps:

[0040] (1) Weigh accurately according to the molar ratio of Sn, Sb, Mn, Ge, Cu and Te of 0.88:0.04:0.08:0.05:0.10:1.05.

[0041] (2) After mixing the above raw materials, place them in a quartz tube and evacuate to a vacuum degree of 5×10. -3 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0042] (3) Place the sealed quartz tube in a muffle furnace for melting reaction, and set its temperature control program as follows: increase the temperature from room temperature to 1000°C in 16 hours. o C, and kept at this temperature for 12 hours. After the reaction is complete, at 20 o Sn was obtained by quenching in water. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-5%Cu2Te compound ingot.

[0043] (4) Grind the ingot obtained from the above reaction in a mortar for 40 minutes to obtain powder material; load it into a graphite mold and perform discharge plasma sintering. The sintering process conditions are: 75 o Rapidly heat to 600°C / min heating rate o C, hold at this temperature for 5 minutes, then slowly cool to room temperature. The sintering pressure is 40 MPa. After sintering, Sn is obtained. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-5%Cu2Te columnar thermoelectric material.

[0044] Example 3

[0045] A low-lattice thermal conductivity tin telluride-based thermoelectric material Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The preparation method of Te-6%Cu2Te includes the following steps:

[0046] (1) Weigh accurately according to the molar ratio of Sn, Sb, Mn, Ge, Cu and Te of 0.88:0.04:0.08:0.05:0.12:1.06.

[0047] (2) After mixing the above raw materials, place them in a quartz tube and evacuate to a vacuum degree of 5×10. -3 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0048] (3) Place the sealed quartz tube in a muffle furnace for melting reaction, and set its temperature control program as follows: increase the temperature from room temperature to 1000°C in 16 hours. o C, and kept at this temperature for 12 hours. After the reaction is complete, at 20 o Sn was obtained by quenching in water. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-6%Cu2Te compound ingot.

[0049] (4) Grind the ingot obtained from the above reaction in a mortar for 40 minutes to obtain powder material; load it into a graphite mold and perform discharge plasma sintering. The sintering process conditions are: 75 o Rapidly increase the temperature to 600°C / min. o C, hold at this temperature for 5 minutes, then slowly cool to room temperature. The sintering pressure is 40 MPa. After sintering, Sn is obtained. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-6%Cu2Te columnar thermoelectric material.

[0050] Example 4

[0051] A low-lattice thermal conductivity tin telluride-based thermoelectric material Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The preparation method of Te-7%Cu2Te includes the following steps:

[0052] (1) Weigh accurately according to the molar ratio of Sn, Sb, Mn, Ge, Cu and Te of 0.88:0.04:0.08:0.05:0.14:1.07.

[0053] (2) After mixing the above raw materials, place them in a quartz tube and evacuate to a vacuum degree of 5×10. -3 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0054] (3) Place the sealed quartz tube in a muffle furnace for melting reaction, and set its temperature control program as follows: increase the temperature from room temperature to 1000°C in 16 hours. o C, and kept at this temperature for 12 hours. After the reaction is complete, at 20 o Sn was obtained by quenching in water. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-7%Cu2Te compound ingot.

[0055] (4) Grind the ingot obtained from the above reaction in a mortar for 40 minutes to obtain powder material; load it into a graphite mold and perform discharge plasma sintering. The sintering process conditions are: 75 o Rapidly increase the temperature to 600°C / min. o C, hold at this temperature for 5 minutes, then slowly cool to room temperature. The sintering pressure is 40 MPa. After sintering, Sn is obtained. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-7%Cu2Te columnar thermoelectric material.

[0056] Example 5

[0057] A low-lattice thermal conductivity tin telluride-based thermoelectric material Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The preparation method of Te-5%Cu2Te includes the following steps:

[0058] (1) Weigh accurately according to the molar ratio of Sn, Sb, Mn, Ge, Cu and Te of 0.88:0.04:0.08:0.05:0.10:1.05.

[0059] (2) After mixing the above raw materials, place them in a quartz tube and evacuate to a vacuum degree of 1×10. -3 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0060] (3) The sealed quartz tube was placed in a muffle furnace for melting reaction. The temperature control program was set as follows: the temperature was raised from room temperature to 950 °C in 12 hours and held at this temperature for 18 hours. After the reaction was completed, Sn was obtained by quenching in water at 10 °C. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-5%Cu2Te compound ingot.

[0061] (4) Grind the ingot obtained from the above reaction in a mortar for 20 min to obtain powder material; load it into a graphite mold and perform discharge plasma sintering. The sintering process conditions are: 50 o Rapidly increase the temperature to 500°C / min. o C, hold at this temperature for 30 minutes, then slowly cool to room temperature. The sintering pressure is 30 MPa. After sintering, Sn is obtained. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-5%Cu2Te columnar thermoelectric material.

[0062] Example 6

[0063] A low-lattice thermal conductivity tin telluride-based thermoelectric material Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The preparation method of Te-6%Cu2Te includes the following steps:

[0064] (1) Weigh accurately according to the molar ratio of Sn, Sb, Mn, Ge, Cu and Te of 0.88:0.04:0.08:0.05:0.12:1.06.

[0065] (2) After mixing the above raw materials, place them in a quartz tube and evacuate to a vacuum degree of 9×10. -2 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0066] (3) The sealed quartz tube was placed in a muffle furnace for melting reaction. The temperature control program was set as follows: the temperature was increased from room temperature to 1100 °C over 20 hours, and held at this temperature for 6 hours. After the reaction was completed, the temperature was increased to 40 °C. Sn was obtained by quenching in water at ℃ 0.88 Sb 0.04 Mn 0.08 Ge 0.05Te-6%Cu2Te compound ingot.

[0067] (4) Grind the ingot obtained from the above reaction in a mortar for 120 min to obtain powder material; load it into a graphite mold and perform discharge plasma sintering. The sintering process conditions are: 100 o Rapidly increase the temperature to 550 °C / min at a heating rate of C / min. o C, hold at this temperature for 20 minutes, then slowly cool to room temperature. The sintering pressure is 60 MPa. After sintering, Sn is obtained. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-6%Cu2Te columnar thermoelectric material.

[0068] Comparative Example 1

[0069] The preparation method of SnTe includes the following steps:

[0070] (1) Weigh Sn and Te accurately according to the molar ratio of Sn to Te of 1:1.

[0071] (2) After mixing the above raw materials, place them in a quartz tube and evacuate to a vacuum degree of less than 5 x 10. -3 After Pa, the quartz tube is sealed with an oxyhydrogen flame.

[0072] (3) Place the sealed quartz tube in a muffle furnace for melting reaction, and set its temperature control program as follows: increase the temperature from room temperature to 1000°C in 16 hours. o C, and kept at this temperature for 12 hours. After the reaction is complete, at 20 o SnTe ingots were obtained by quenching in water.

[0073] The ingot obtained from the above reaction was ground in a mortar for 40 minutes to obtain powder material; it was then placed into a graphite mold and subjected to discharge plasma sintering under the following conditions: 75 o Rapidly increase the temperature to 600°C / min. o C, hold at the temperature for 5 minutes, then slowly cool to room temperature, sintering pressure is 40 MPa, and SnTe thermoelectric material is obtained after sintering.

[0074] Figure 1 The X-ray diffraction patterns of the materials obtained in Examples 1-4 and the SnTe obtained in the comparative example are shown. The main diffraction peaks are completely consistent with the SnTe standard card PDF#46-1210, indicating that the thermoelectric material with tin telluride as the main phase was successfully prepared by the preparation method of the present invention.

[0075] Figure 2 , 34 and 4 represent the conductivity, Sebke coefficient, and power factor of the materials obtained in Examples 1-4 and Comparative Example 1, respectively. Due to the optimization of the band structure and carrier concentration of tin telluride by Sb, Mn, Ge, and Cu doping, all Sn... 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The Te-x%Cu2Te sample exhibits superior electrical properties compared to undoped tin telluride. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The power factor of the Te-5%Cu2Te sample reached 25.6 μW cm⁻¹. -1 K -2 .

[0076] Figure 5 and 6 The thermal conductivity and lattice thermal conductivity of the materials obtained in 1-4 and the SnTe obtained in Comparative Example 1 are respectively. 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The Te-x%Cu2Te sample exhibits lower thermal conductivity than undoped tin telluride. This is because the Cu2Te alloy induces a core-shell structure in the tin telluride, such as... Figure 6 As shown, Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The lattice thermal conductivity of Te-5%Cu2Te decreases to 0.21 W / m. -1 K -1 .

[0077] Figure 7 The thermoelectric figure of merit of the materials obtained in Implementations 1-4 and the SnTe obtained in the comparative example are respectively shown. Thanks to the synergistic regulation of thermoelectric transport, the optimal Sn composition... 0.88 Sb 0.04 Mn 0.08 Ge 0.05 The maximum thermoelectric figure of merit for the Te-5%Cu2Te sample is 600. o At C, it is 1.5, which is 4.3 times the thermoelectric figure of merit of undoped tin telluride, making it an ideal environmentally friendly thermoelectric material to replace toxic lead telluride materials.

[0078] Figure 8 These are scanning transmission electron microscope images of the material obtained in Example 2. Figure 8 (a) indicates that the size of the precipitated phase is 50-200 nanometers. Figure 8(b) shows the distribution of Sn, Te, Ge, Mn, Cu and Sb elements. Cu and Mn elements show obvious aggregation and exhibit core-shell characteristics.

[0079] Of the above embodiments, the embodiment with the best overall performance is Embodiment 2.

[0080] Comparative Example 2

[0081] The remaining steps of this comparative example are the same as those of Example 2, except that the raw material molar ratio in step (1) is replaced with 0.88:0.04:0.08:0.05:0.06:1.03. The above characterization of electrical and thermal transport properties revealed that electrical conductivity, power factor, and thermoelectric figure of merit significantly decreased, while thermal conductivity and lattice thermal conductivity significantly increased. Figure 2-7 As shown.

[0082] Comparative Example 3

[0083] The remaining steps of this comparative example are the same as those in Example 2, except that the molar ratio of the raw materials in step (1) is replaced with 0.88:0.04:0.08:0.05:0.12:1.06. The above-mentioned characterization of electrical and thermal transport properties revealed that electrical conductivity and thermoelectric performance decreased significantly, while thermal conductivity and lattice thermal conductivity increased significantly. Figure 2-7 As shown.

[0084] Comparative Example 4

[0085] The remaining steps of this comparative example are the same as those of Example 2, except that the temperature control program in step (3) is replaced by heating from room temperature to 1000 ℃ in 10 hours and holding at this temperature for 5 hours. If the heating rate is too fast and the holding time is too short, component segregation may occur, which is not conducive to obtaining high-performance thermoelectric materials.

[0086] Comparative Example 5

[0087] The remaining steps of this comparative example are the same as those of Example 2, except that the temperature control procedure in step (3) is replaced by raising the temperature from room temperature to 1000 ℃ over 25 hours and holding it at this temperature for 20 hours. The slower heating rate and longer holding time are more conducive to obtaining ingots with uniform composition, but the longer experimental time increases the energy consumption.

[0088] Comparative Example 6

[0089] The remaining steps of this comparative example are the same as those of Example 2, except that the temperature increase in step (4) is replaced with 450°C and the sintering pressure is replaced with 20 MPa. Too low a sintering temperature and too low a pressure will lead to insufficient sintering, which reduces the density of the sintered product and is not conducive to achieving high-performance SnTe thermoelectric materials.

[0090] Comparative Example 7

[0091] The remaining steps of this comparative example are the same as those of Example 2, except that the temperature increase in step (4) is replaced with 650°C and the sintering pressure is replaced with 70 MPa. Increasing the sintering temperature and pressure is beneficial to increasing the density of the sintered product, but high temperature and high pressure can lead to sintering defects, which reduces the experimental yield.

Claims

1. A tin telluride-based thermoelectric material with low lattice thermal conductivity, characterized in that: Its chemical formula is Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-x%Cu2Te, where 0 <x≤7。 2. The low lattice thermal conductivity tin telluride-based thermoelectric material according to claim 1, characterized in that: Its chemical formula is Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-3%Cu2Te, Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-5%Cu2Te, Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-6%Cu2Te or Sn 0.88 Sb 0.04 Mn 0.08 Ge 0.05 Te-7%Cu2Te.

3. A method for preparing a low-lattice thermal conductivity tin telluride-based thermoelectric material according to claim 1 or 2, characterized in that, Includes the following steps: Step 1: Weigh the raw materials Sn, Te, Sb, Mn, Ge, and Cu according to stoichiometry; Step 2: After mixing the raw materials, transfer them to a quartz tube, evacuate the vacuum, and seal the tube with an oxyhydrogen flame. Step 3: Heat the quartz tube containing the mixture to carry out the melting reaction. After the reaction is completed, quench the mixture in water to obtain SnTe ingots. Step four: Grind the SnTe ingot into powder, put it into a mold and sinter it to obtain a tin telluride-based thermoelectric material with low lattice thermal conductivity.

4. The method for preparing the low-lattice thermal conductivity tin telluride-based thermoelectric material according to claim 3, characterized in that: In step one, the molar ratio of Sn, Te, Sb, Mn, Ge, and Cu is 0.88:0.04:0.08:0.05:0.06~0.14:1.03~1.

07.

5. The method for preparing the low-lattice thermal conductivity tin telluride-based thermoelectric material according to claim 3, characterized in that: In step two, the vacuum level inside the quartz tube is less than 10 after evacuation. -2 Pa.

6. The method for preparing the low-lattice thermal conductivity tin telluride-based thermoelectric material according to claim 3, characterized in that: In step three, the heating process involves raising the temperature from room temperature to 950-1100 ℃ over 12-20 hours, and then maintaining this temperature for 6-18 hours.

7. The method for preparing the low-lattice thermal conductivity tin telluride-based thermoelectric material according to claim 3, characterized in that: In step three, quenching is performed in water at 10~40 ℃.

8. The method for preparing the low-lattice thermal conductivity tin telluride-based thermoelectric material according to claim 3, characterized in that: In step four, the grinding time is 20-120 minutes.

9. The method for preparing the low-lattice thermal conductivity tin telluride-based thermoelectric material according to claim 3, characterized in that: In step four, sintering involves heating to 500-600°C at a heating rate of 50-100°C / min and holding at that temperature for 5-30 minutes.

10. The method for preparing the low-lattice thermal conductivity tin telluride-based thermoelectric material according to claim 3, characterized in that: In step four, the sintering pressure is 30~60 MPa.

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