Bismuth telluride-based thermoelectric power generation material and preparation method thereof

Abstract

The invention belongs to the technical field of energy materials, and discloses a bismuth telluride-based thermoelectric material, which has the following general formula: Bi < 0.4 > Sb < 1.6-x-y > Ga < x > Cu < y > Te < 3 >, 0 < x < = 0.1, and 0 < y < = 0.0125. The invention also provides a preparation method which comprises the following steps: step 1, mixing a Bi source, an Sb source, a Ga source, a Te source and a Cu source, sealing a tube in vacuum, melting at high temperature, and carrying out water quenching to obtain a bismuth telluride-based cast ingot; 2, grinding the bismuth telluride-based cast ingot into fine powder, and performing hot pressed sintering to obtain a P-type bismuth telluride block material; and step 3, texturing the P-type bismuth telluride block material to obtain the bismuth telluride-based thermoelectric material. The bismuth telluride-based thermoelectric material has excellent thermoelectric performance, the carrier mobility is effectively enhanced and the lattice thermal conductivity is reduced through the Ga and Cu double-doped synergistic effect and texturing treatment, so that the coupling relation between the electrical transport performance and the thermal performance is decoupled, and the thermoelectric performance of the bismuth telluride-based thermoelectric material is improved.

Description

Technical Field

[0001] This invention belongs to the field of energy materials technology, and relates to bismuth telluride-based thermoelectric power generation materials and their preparation methods. Background Technology

[0002] In today's world, fossil fuel energy is scarce and environmental problems are becoming increasingly prominent. Thermoelectric materials are a class of functional materials that can directly convert heat energy into electrical energy, and they have the advantages of being noiseless, pollution-free, and highly reliable. Thermoelectric materials have attracted widespread attention because they can be used for waste heat recovery power generation and solid-state refrigeration.

[0003] Bismuth telluride-based thermoelectric materials are currently the only commercially available thermoelectric materials and are the most widely used in industrial applications. Their thermoelectric performance directly affects the power generation efficiency of thermoelectric devices. Therefore, it is necessary to further optimize the performance of bismuth telluride-based thermoelectric materials.

[0004] The dimensionless thermoelectric figure of merit (ZT) is an important indicator for evaluating the performance of thermoelectric materials. ZT is also an important measure of the efficiency of thermoelectric power generation devices. Therefore, increasing the ZT value of a material will further improve the conversion efficiency of thermoelectric power generation devices.

[0005] The dimensionless thermoelectric figure of merit (ZT) is expressed as ZT = S²σT / κ, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature. Therefore, the formula shows that the performance of thermoelectric materials is directly related to the Seebeck coefficient, electrical conductivity, and thermal conductivity. By optimizing the coupling relationship among these three factors—that is, increasing the Seebeck coefficient and electrical conductivity while decreasing thermal conductivity—the thermoelectric figure of merit (ZT) of thermoelectric materials can be effectively improved. Currently, industrially available p-type bismuth telluride exhibits relatively low performance due to its excessively high thermal conductivity, resulting in a ZT value of around 1.2. Summary of the Invention

[0006] 1. The technical problem to be solved:

[0007] This invention provides a bismuth telluride-based thermoelectric material with excellent performance, characterized by low thermal conductivity and high ZT value.

[0008] 2. Technical Solution:

[0009] To address the above problems, this invention provides a bismuth telluride-based thermoelectric material, wherein the bismuth telluride-based thermoelectric material is a p-type bismuth telluride-based material with the chemical formula Bi. 0.4 Sb 1.6-x-y Ga x Cu y Te3, 0<x≤0.1, 0<y≤0.0125.

[0010] The present invention also provides a method for preparing the bismuth telluride-based thermoelectric material as described above, comprising the following steps:

[0011] Step 1: Mix Bi source, Sb source, Ga source, Te source and Cu source, vacuum seal tube, melt at high temperature and water quench to obtain bismuth telluride-based ingot.

[0012] Step 2: Grind the bismuth telluride-based ingot into fine powder, and hot press and sinter it to obtain P-type bismuth telluride bulk material.

[0013] Step 3: Texture the p-type bismuth telluride bulk material to obtain the chemical formula Bi. 0.4 Sb 1.6-x- y Ga x Cu y Te 3的 Bismuth telluride-based thermoelectric materials.

[0014] In step 1, according to the stoichiometric ratio Bi 0.4 Sb 1.6-x-y Ga x Cu y Te3 is named after Bi, Sb, Ga, Te, and Cu sources.

[0015] Vacuum degree 10 -2 Vacuum sealing under Pa conditions.

[0016] In step 1, the high-temperature melting temperature is 800-1300 ℃, and the time is 5-15 h.

[0017] The Bi source is elemental Bi, the Sb source is elemental Sb, the Ga source is elemental Ga, the Te source is elemental Te, and the Cu source is elemental Cu.

[0018] In step 2, the fine powder is ground to a grain size of 0.5-3 μm.

[0019] In step 2, the specific method of hot pressing sintering is as follows: under a vacuum degree <10 -2 The temperature is raised to 400-500 ℃, and the sintering pressure is raised to 30-70 MPa. The temperature and pressure are maintained for 30-120 min.

[0020] In step 3, the texturing includes: In step 3, the specific method of texturing is: under a vacuum degree < 10 -2 At a constant temperature of 550-700 ℃, the sintering pressure is increased to 10-40 MPa and held at that temperature and pressure for 10-50 min. Then, the sintering pressure is increased to 40-100 MPa and held at that temperature and pressure for 30-150 min.

[0021] 3. Beneficial effects:

[0022] The bismuth telluride-based thermoelectric material provided by this invention is a polycrystalline P-type bismuth telluride-based thermoelectric material with excellent thermoelectric properties, and its ZT can reach as high as 1.6 at 450K.

[0023] The method for preparing bismuth telluride-based thermoelectric materials provided by this invention involves dual-atom doping with Bi... 0.4 Sb 1.6 Compared to Te3-based bismuth telluride thermoelectric materials, the thermoelectric performance is improved by 48%.

[0024] The method for preparing bismuth telluride-based thermoelectric materials provided by this invention utilizes Ga doping to form a heterogeneous interface that effectively reduces lattice thermal conductivity, thereby improving the thermal performance of the bismuth telluride-based thermoelectric material. Cu doping effectively improves carrier concentration, thereby improving the electrical transport performance of the bismuth telluride-based thermoelectric material. Furthermore, Cu forms a dual-doped structure with Ga, creating multiple grain boundaries and dislocations that enhance phonon scattering, further reducing lattice thermal conductivity. This decouples the coupling relationship between electrical transport performance and thermal conduction, thus synergistically improving the thermoelectric performance of the bismuth telluride-based thermoelectric material.

[0025] The method for preparing bismuth telluride-based thermoelectric materials provided by this invention employs hot pressing sintering, atomic double doping, and thermal texturing treatment to reduce the thermal conductivity of P-type bismuth telluride-based thermoelectric materials. The grains are clearly aligned along the direction of performance advantage, which effectively improves the preferred orientation of the material and enhances the carrier mobility. Attached Figure Description

[0026] Figure 1 The comparison graph of σ-T curves in Example 1 is shown.

[0027] Figure 2 The ST curve comparison chart in Example 1 is shown.

[0028] Figure 3 The comparison graph of κ-T curves in Example 1 is shown.

[0029] Figure 4 The ZT-T curve comparison chart in Example 1 is shown. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] The purpose of this invention is to provide the application of bismuth telluride-based thermoelectric materials prepared by the method described in the first aspect or the second aspect in thermoelectric devices.

[0032] This invention provides a bismuth telluride-based thermoelectric material, wherein the bismuth telluride-based thermoelectric material is a p-type bismuth telluride-based material with the chemical formula Bi. 0.4 Sb1.6-x-y Ga x Cu y Te3, 0 < x ≤ 0.1, 0 < y ≤ 0.02, preferably 0 < x ≤ 0.1, 0 < y ≤ 0.0125, more preferably x = 0.005, y = 0.0025.

[0033] The introduction of Ga and Cu co-doping can improve the charge carrier capacity and reduce the lattice thermal conductivity of bismuth telluride-based thermoelectric materials. Furthermore, the amount of Cu added is highly sensitive to the Seebeck coefficient, electrical conductivity, and thermal conductivity of the bismuth telluride-based thermoelectric material, i.e., the thermoelectric dimensionless figure of merit (ZT). As the value of y increases, the ZT value of the bismuth telluride-based thermoelectric material first increases and then decreases. When 0 < y ≤ 0.0125, the ZT value of the co-doped bismuth telluride-based thermoelectric material reaches above 1.0 at room temperature. When y = 0.0025, the ZT value can reach as high as 1.3, and after further texturing, the ZT value increases to 1.6. The synergistic doping of Ga and Cu improves the thermoelectric performance of bismuth telluride-based thermoelectric materials.

[0034] The present invention also provides a method for preparing the bismuth telluride-based thermoelectric material, the method comprising:

[0035] Step 1: After mixing Bi source, Sb source, Ga source, Te source and Cu source, vacuum sealing, high temperature melting, and water quenching are performed to obtain bismuth telluride-based ingot.

[0036] Wherein, the Bi source is elemental Bi, the Sb source is elemental Sb, the Ga source is elemental Ga, the Cu source is an elemental substance, and the Te source is elemental Te.

[0037] According to Bi 0.4 Sb 1.6-x-y Ga x Cu y Te3 is made up of Bi source, Sb source, Ga source, Cu and Te source, wherein 0 < x ≤ 0.1, 0 < y ≤ 0.015, preferably 0 < x ≤ 0.01, 0 < y ≤ 0.0125, more preferably x is 0.005 and y is 0.0025.

[0038] According to the present invention, the heterogeneous interface formed by Ga doping effectively reduces the lattice thermal conductivity, thereby improving the thermal performance of the bismuth telluride-based thermoelectric material; furthermore, Cu doping effectively improves the carrier concentration, thereby improving the electrical transport performance of the bismuth telluride-based thermoelectric material, and forms a double-doped structure with Ga, constituting multiple grain boundaries and dislocations to enhance phonon scattering, reducing the lattice thermal conductivity, thereby decoupling the coupling relationship between electrical transport performance and thermal conduction. The two interact and synergistically improve the thermoelectric performance of the bismuth telluride-based thermoelectric material.

[0039] In step 1, the Te source, Bi source, Sb source, Ga source and Cu source are sequentially filled into the quartz tube and sealed under vacuum conditions. Then, they are melted in a high-temperature environment.

[0040] By sequentially filling the quartz tube with Te, Bi, Sb, Ga, and Cu sources, the excessive volatilization of Te during the sealing process can be reduced, which can lead to uneven composition.

[0041] Vacuum conditions can prevent the oxidation of raw materials, which leads to a low yield. The vacuum level is below 10. -2 Pa is better.

[0042] The high-temperature melting temperature is 800-1300 ℃, preferably 1000-1200 ℃, more preferably 1100 ℃; the time is 5-15 h, preferably 8-12 h, more preferably 10 h.

[0043] High temperatures can melt reactants in a short time. Extending the high-temperature melting time can allow the reactants to mix more evenly, thus improving material properties; however, excessively long times are unnecessary. Therefore, the high-temperature melting process parameters need to be strictly controlled. Within the aforementioned range of high-temperature melting parameters, the resulting bismuth telluride-based thermoelectric material exhibits the best performance.

[0044] Step 2: Grind the bismuth telluride-based ingot into fine powder, and hot press and sinter it to obtain P-type bismuth telluride bulk material.

[0045] Before sintering, the bismuth telluride is ground to obtain a fine powder. The grinding is done manually, and the grinding time is 5-40 minutes, preferably 10-20 minutes, for example, 15 minutes.

[0046] In step 2, the sintering includes: at a vacuum degree <10 -2 The temperature is increased to 400-500 ℃, and the sintering pressure is increased to 40-100 MPa, and the temperature and pressure are held for 30-120 min. If the temperature is lower than 420 ℃, the material cannot be fully sintered, which will result in insufficient material density and uneven grain distribution. At the same time, the bismuth telluride-based thermoelectric material will have voids inside, thus affecting the thermoelectric performance of the material.

[0047] In one embodiment, the vacuum level is <10. -2 The temperature is raised to 420-460 ℃, and the sintering pressure is raised to 40-80 MPa, and the temperature and pressure are maintained for 30-90 min.

[0048] In one embodiment, the vacuum level is <10. -2 The temperature was raised to 440 ℃ and the sintering pressure was raised to 60 MPa, and the temperature and pressure were maintained for 60 min.

[0049] Step 3: Texture the P-type bismuth telluride bulk material to obtain the bismuth telluride-based thermoelectric material.

[0050] The texturing includes: in a vacuum degree <10 -2 The temperature is increased to 550-700 ℃, and the sintering pressure is increased to 10-40 MPa, and the temperature and pressure are held for 10-50 min. Then the sintering pressure is increased to 40-100 MPa, and the temperature and pressure are held for 30-150 min.

[0051] Differences in crystal structure and grain growth have a significant impact on the performance of thermoelectric materials. Due to the anisotropy of bismuth telluride-based thermoelectric materials, their thermoelectric properties differ depending on whether they grow along the crystal plane or perpendicular to it. The grains of bismuth telluride-based thermoelectric materials prepared by hot pressing and texturing clearly grow along the direction of superior performance, enhancing the preferred orientation, increasing carrier mobility, and effectively reducing lattice thermal conductivity, thus significantly improving the performance of bismuth telluride-based thermoelectric materials.

[0052] In one embodiment, the texturing includes: vacuum degree <10 -2 The temperature is increased to 580-650 ℃, and the sintering pressure is increased to 15-30 MPa, and the temperature and pressure are held for 20-40 min. Then the sintering pressure is increased to 40-80 MPa, and the temperature and pressure are held for 50-80 min.

[0053] In one embodiment, the texturing includes: vacuum degree <10 -2 The temperature was increased to 630 °C, and the sintering pressure was increased to 20 MPa. The temperature and pressure were maintained for 30 min. Then the sintering pressure was increased to 60 MPa, and the temperature and pressure were maintained for 60 min.

[0054] The heterogeneous interface formed by Ga doping effectively reduces the lattice thermal conductivity, thereby improving the thermal performance of the bismuth telluride-based thermoelectric material. Cu doping effectively improves the carrier concentration, thereby improving the electrical transport performance of the bismuth telluride-based thermoelectric material. It also forms a double-doped structure with Ga, creating multiple grain boundaries and dislocations to enhance phonon scattering and reduce the lattice thermal conductivity. This decouples the coupling relationship between electrical transport performance and thermal conduction. The two interact and synergistically improve the thermoelectric performance of the bismuth telluride-based thermoelectric material.

[0055] Example 1

[0056] According to the stoichiometric ratio Bi 0.4 Sb 1.5925 Ga 0.005 Cu 0.00252.8965 g of elemental Te, 0.6325 g of elemental Bi, 1.4672 g of elemental Sb, 0.0026 g of elemental Ga, and 0.0012 g of elemental Cu were weighed out sequentially and placed into a quartz tube according to the Te, Bi, Sb, Ga, and Cu source order. This reduces the risk of uneven composition due to the volatilization of Te during the sealing process. (With a vacuum degree of 10...) -2 The quartz tube was then sealed under Pa conditions. Subsequently, the quartz tube was placed in a vertical melting furnace and heated to 1100 °C and held for 10 h. It was then water-quenched at 1100 °C to obtain a bismuth telluride-based ingot.

[0057] The prepared bismuth telluride-based ingot was manually ground in a mortar for 15 minutes to obtain a fine powder. The powder was then placed in a 10 mm diameter graphite mold and sintered in a hot-pressing furnace according to the following procedure: under a vacuum degree <10... -2 The temperature was raised to 440 °C, and the sintering pressure was increased to 60 MPa. The temperature and pressure were held for 60 min. The sample was then cooled to room temperature and removed to obtain P-type bismuth telluride bulk material.

[0058] P-type bismuth telluride bulk material was placed in a graphite mold with a diameter of 15.5 mm and textured according to the following procedure: under a vacuum degree <10 -2 The temperature was raised to 630 °C, and the sintering pressure was increased to 20 MPa, held at that temperature and pressure for 30 min. Then the sintering pressure was increased to 60 MPa, held at that temperature and pressure for 60 min. The resulting bismuth telluride bulk material was further placed in a 20 mm diameter graphite mold and textured according to the following procedure: under a vacuum degree <10... -2 The temperature was increased to 630 °C, and the sintering pressure was increased to 20 MPa, with a holding time of 30 min. Then, the sintering pressure was increased to 60 MPa, and the holding time was 60 min. The textured bismuth telluride-based thermoelectric material with the chemical formula Bi was obtained. 0.4 Sb 1.5925 Ga 0.005 Cu 0.0025 Te3.

[0059] The prepared Bi was measured 0.4 Sb 1.5925 Ga 0.005 Cu 0.0025 The ZT value of Te3 at 425 K is 1.63.

[0060] Example 2

[0061] According to the stoichiometric ratio Bi 0.4 Sb 1.5925 Ga 0.005 Cu 0.00252.8962 g of elemental Te, 0.6326 g of elemental Bi, 1.4670 g of elemental Sb, 0.0025 g of elemental Ga, and 0.0014 g of elemental Cu were weighed out sequentially and placed into a quartz tube according to the Te, Bi, Sb, Ga, and Cu source order. This reduces the risk of uneven composition due to the volatilization of Te during the sealing process. (With a vacuum degree of 10...) -2 The quartz tube was then sealed under Pa conditions. Subsequently, the quartz tube was placed in a vertical melting furnace and heated to 1100 °C and held for 10 h. It was then water-quenched at 1100 °C to obtain a bismuth telluride-based ingot.

[0062] The prepared bismuth telluride-based ingot was manually ground in a mortar for 15 minutes to obtain a fine powder. The powder was then placed in a 10 mm diameter graphite mold and sintered in a hot-pressing furnace according to the following procedure: under a vacuum degree <10... -2 The temperature was raised to 440 °C, and the sintering pressure was increased to 60 MPa. The temperature and pressure were held for 60 min. The sample was then cooled to room temperature and removed to obtain P-type bismuth telluride bulk material.

[0063] P-type bismuth telluride bulk material was placed in a graphite mold with a diameter of 15.5 mm and textured according to the following procedure: under a vacuum degree <10 -2 The temperature was raised to 630 °C, and the sintering pressure was increased to 20 MPa, held at that temperature and pressure for 30 min. Then the sintering pressure was increased to 60 MPa, held at that temperature and pressure for 60 min. The resulting bismuth telluride bulk material was further placed in a 20 mm diameter graphite mold and textured according to the following procedure: under a vacuum degree <10... -2 The temperature was increased to 630 °C, and the sintering pressure was increased to 20 MPa, with a holding time of 30 min. Then, the sintering pressure was increased to 60 MPa, and the holding time was 60 min. The textured bismuth telluride-based thermoelectric material with the chemical formula Bi was obtained. 0.4 Sb 1.5925 Ga 0.005 Cu 0.0025 Te3.

[0064] The prepared Bi was measured 0.4 Sb 1.5925 Ga 0.005 Cu 0.0025 The ZT value of Te3 at 425 K is 1.6.

[0065] Comparative Example 1

[0066] Bismuth telluride-based thermoelectric materials were prepared in a manner similar to that in Example 1. 0.4 Sb 1.5925 Ga 0.005 Cu0.0025 Te3 differs in that it does not undergo texturing.

[0067] The prepared Bi was measured 0.4 Sb 1.5925 Ga 0.005 Cu 0.0025 The ZT value of Te3 at 400 K is 1.3.

[0068] The bismuth telluride-based thermoelectric materials prepared in Examples 1, 2, and 1 were processed into bulk samples of 2*2*8 mm, and their electrical properties were tested after polishing. The bismuth telluride-based thermoelectric materials prepared in Examples 1, 2, and 2 were processed into bulk samples with a diameter of 10 mm, and their thermal properties were tested after polishing. The results are as follows: Figures 1 to 4 As shown, where, Figure 1 The diagram shows a comparison of the σ-T curves of the bismuth telluride-based thermoelectric materials prepared in Example 1, Example 2, and Comparative Example 1. Figure 2 The ST curves of the bismuth telluride-based thermoelectric materials prepared in Example 1, Example 2, and Comparative Example 1 are shown in comparison. Figure 3 The graph shows a comparison of the κ-T curves of the bismuth telluride-based thermoelectric materials prepared in Example 1, Example 2, and Comparative Example 1. Figure 4 The ZT-T curves of the bismuth telluride-based thermoelectric materials prepared in Example 1, Example 2 and Comparative Example 1 are shown in comparison.

[0069] Comparative Example 2

[0070] Cu-doped bismuth telluride materials, based on the chemical formula Cu 0.005 Bi 0.3 Sb 1.695 Te3 high-purity elemental substances were weighed and placed into a quartz tube. The tube was then sealed using a plasma gun in a glove box filled with an argon inert atmosphere. The sealed quartz tube was placed in a vertical melting furnace for melting, heated to 1100 °C at a rate of 1.5 °C / min, and held at this temperature for 12 hours before quenching. The quenched quartz tube containing the sample was directly placed in an annealing furnace for annealing at 400 °C for 5 days. Finally, the obtained bismuth telluride bulk was ground into powder and prepared into a dense bulk by spark plasma sintering (SPS). The sintering temperature was between 400 °C and 450 °C, the sintering pressure was 50 MPa, and the temperature and pressure were held for 10 min. Thermoelectric performance tests showed that the material had better thermoelectric properties in the direction parallel to the sintering pressure, and the electrical conductivity of this material was higher than that of Bi. 0.3 Sb 1.7 Te3 is improved to a certain extent, while the lattice thermal conductivity is reduced, making the Cu material... 0.005 Bi 0.3 Sb 1.695The thermoelectric figure of merit (ZT) of Te3 material is 1.24 at 500K and remains at 1.2 at 550K. The average ZT is 1.2 within the operating temperature range of bismuth telluride power generation devices (350K~550K).

[0071] Although Cu doping in Comparative Example 2 increases electrical conductivity, the Seebeck coefficient decreases significantly, and the thermal conductivity in the vertical direction does not decrease but increases instead, with ZT only 1.2 at 550K.

[0072] Comparative Example 3

[0073] Ga-doped bismuth telluride materials, based on the chemical formula Bi 0.35 Sb 1.63 Ga 0.02 Te3, according to stoichiometric ratio, weigh out elemental raw materials Bi, Sb, Ga, and Te (each element having a purity ≥ 99.999%), load the prepared raw materials into a quartz tube, and seal the quartz tube with an oxyhydrogen flame to create a sealed high-vacuum environment to 1 × 10⁻⁶. -3 Pa is used for vacuum sealing; the sealed quartz tube is placed in a muffle furnace and heated to 800 °C at a rate of 100 °C per hour, and held for 600 min to allow the mixture to react fully in a high-temperature molten state. Then, the temperature is lowered to 650 °C within 220 min and held for 600 min. Finally, the temperature is lowered to room temperature within 220 min, and the metal ingot is removed from the quartz tube. Metal ingots were placed in a ball mill jar, and grinding balls with diameters of 15 mm, 12 mm, 7 mm, and 5 mm were added to the jar in a ratio of 1:3:10:22. The ball mill was operated at a speed of 1000 r / min for 20 min, and the powder was obtained after thorough grinding. Subsequently, vacuum discharge plasma sintering was performed. Molds with diameters of 15 mm and 20 mm were used successively to raise the temperature to 500 °C at a rate of 100 °C per minute, maintain the sintering pressure at 50 MPa, and hold for 5 min. After cooling, the gallium-containing bismuth telluride-based thermoelectric material was obtained.

[0074] Although Ga doping in Comparative Example 3 reduces thermal conductivity, it contributes almost nothing to the electrical properties of the material, with ZT only 1.06 at 425 K.

[0075] When faced with the above-mentioned defects, those skilled in the art would tend to choose one optimization rather than risk combining them, because: Ga grain boundary precipitation will introduce a potential barrier, which may offset the carrier boost of Cu; Cu carrier concentration is too high, which may destroy the energy filtering effect of Ga; therefore, dual doping is not an obvious choice, but an innovation that breaks through technical bias.

[0076] In this invention, Cu and Ga co-doping is not a performance trade-off or linear superposition, but rather achieves synergistic optimization through: Cu optimizing carrier concentration; Ga constructing a dislocation network and energy filtering; Ga liquid-phase lubrication during texturing combined with Cu stabilizing grain boundaries; and electro-thermal decoupling and orientation enhancement. The effect far exceeds that of single doping. The Bi obtained in Example 1 was measured to be... 0.4 Sb 1.5925 Ga 0.005 Cu 0.0025 Te3 has a ZT value as high as 1.63 at 425K.

Claims

1. A bismuth telluride-based thermoelectric material, characterized in that, The bismuth telluride-based thermoelectric material is a p-type bismuth telluride-based material with the chemical formula Bi. 0.4 Sb 1.6-x-y Ga x Cu y Te3, 0<x≤0.1, 0<y≤0.0125.

2. A method for preparing the bismuth telluride-based thermoelectric material as described in claim 1, characterized in that: Includes the following steps: Step 1: After mixing Bi source, Sb source, Ga source, Te source and Cu source, vacuum sealing, high temperature melting, and water quenching, bismuth telluride-based ingots are obtained. Step 2: Grind the bismuth telluride-based ingot into fine powder, and hot-press and sinter it to obtain P-type bismuth telluride bulk material; Step 3: Texture the p-type bismuth telluride bulk material to obtain the chemical formula Bi. 0.4 Sb 1.6-x-y Ga x Cu y Te 3的 Bismuth telluride-based thermoelectric materials.

3. The preparation method according to claim 2, characterized in that: In step 1, according to the stoichiometric ratio Bi 0.4 Sb 1.6-x- y Ga x Cu y Te3 is named after Bi, Sb, Ga, Te, and Cu sources.

4. The preparation method according to claim 3, characterized in that: Vacuum degree 10 -2 Vacuum sealing under Pa conditions.

5. The preparation method according to claim 2, characterized in that: In step 1, the high-temperature melting temperature is 800-1300℃, and the time is 5-15 h.

6. The preparation method according to claim 2, characterized in that: The Bi source is elemental Bi, the Sb source is elemental Sb, the Ga source is elemental Ga, the Te source is elemental Te, and the Cu source is elemental Cu.

7. The preparation method according to claim 1, characterized in that: In step 2, the fine powder is ground to a grain size of 0.5-3 μm.

8. The preparation method according to claim 2, characterized in that: In step 2, the specific method of hot pressing sintering is as follows: under a vacuum degree <10 -2 The temperature is raised to 400-500 ℃, and the sintering pressure is raised to 30-70 MPa. The temperature and pressure are maintained for 30-120 minutes.

9. The preparation method according to claim 2, characterized in that: In step 3, the texturing includes: In step 3, the specific method of texturing is: under a vacuum degree < 10 -2 At a constant temperature of 550-700 ℃, the sintering pressure is increased to 10-40 MPa and held at that temperature and pressure for 10-50 min. Then, the sintering pressure is increased to 40-100 MPa and held at that temperature and pressure for 30-150 min.

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