A bismuth telluride composite thermoelectric long strip and a preparation method thereof
By developing a method for preparing bismuth telluride composite thermoelectric long bands, the problem of preparing large-size Bi2Te3 thermoelectric thin films has been solved, and high-performance thermoelectric thin films with small grain size and good density have been achieved, making them suitable for the field of thermoelectric materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF ELECTRICAL ENG CHINESE ACAD OF SCI
- Filing Date
- 2023-06-29
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies are difficult to use to prepare large-size, high-performance Bi2Te3 thermoelectric thin films due to low preparation efficiency and limited large-scale applications.
Bi(NO3)3·5H2O and Na2TeO3 were mixed with ethylene glycol, and the pH value was adjusted to 7.5-8.5. Carbon nanotubes and ethylene glycol were added to form a precursor solution for a composite thermoelectric thin film. The solution was coated on a polyimide substrate and then subjected to phase formation heat treatment and annealing to prepare a bismuth telluride composite thermoelectric long strip.
Large-size Bi2Te3 thermoelectric thin films with lengths of 50–100 m were prepared. These films have small and dense grains, a layered structure, and excellent electrical conductivity and Seebeck coefficient.
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Figure CN116828952B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of thermoelectric functional coating technology, and in particular to a bismuth telluride composite thermoelectric long strip and its preparation method. Background Technology
[0002] Thermoelectric materials are materials that enable the direct conversion of heat energy into electrical energy, and can be used for thermoelectric power generation and refrigeration. Bi₂Te₃-based compounds are the thermoelectric materials with the best room-temperature performance. After decades of research, the thermoelectric figure of merit of bulk Bi₂Te₃-based materials has hovered around 1. With the rise of nanotechnology, reports of achieving high thermoelectric figures of merit in low-dimensional materials have emerged in recent years. Refining the grain size of materials to the nanoscale or adding nanoscale second-phase particles to the material and reducing the material's dimensionality can increase the scattering of charge carriers and phonons, improve the Seebeck coefficient, reduce thermal conductivity, and enhance thermoelectric performance.
[0003] Bi₂Te₃ thermoelectric thin film materials have a lower dimension than bulk materials. On one hand, the lower dimension leads to interfacial scattering effects, reducing the material's thermal conductivity and increasing its ZT value. Furthermore, when the film thickness is on the nanometer scale, it can also generate a quantum confinement effect, improving the material's power factor. On the other hand, low-dimensional thermoelectric materials possess high response speeds (23,000 times faster than bulk materials), high cooling and heating performance, high energy density, and the ability to achieve small-scale static localization. Therefore, thermoelectric thin films have become a research hotspot in recent years.
[0004] Currently, some sputtering and chemical solution methods can prepare Bi2Te3 thermoelectric thin films, but these are all static methods, and the resulting samples are only a few centimeters in size, making them too small for practical applications. For example, Chinese patent CN103060750A successfully prepared thermoelectric thin films using magnetron sputtering, but the thermoelectric thin films prepared in this patent are only a few centimeters in size, resulting in low preparation efficiency and making it difficult to produce on a large scale.
[0005] Therefore, providing a method for preparing large-size, high-performance thermoelectric thin films has become a pressing technical problem to be solved in this field. Summary of the Invention
[0006] The purpose of this invention is to provide a bismuth telluride composite thermoelectric long strip and its preparation method. The bismuth telluride composite thermoelectric long strip provided by this invention is 50-100m long, with a large thermoelectric film size, good coating density and small grain size.
[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0008] This invention provides a method for preparing bismuth telluride composite thermoelectric long bands, comprising the following steps:
[0009] (1) Mix Bi(NO3)3·5H2O and Na2TeO3 with ethylene glycol, and then adjust the pH value to 7.5-8.5 to obtain a mixed solution;
[0010] (2) Add carbon nanotubes and ethylene glycol to the mixed solution obtained in step (1), and after mixing, obtain a composite thermoelectric film precursor solution;
[0011] (3) The composite thermoelectric thin film precursor liquid obtained in step (2) is coated on a polyimide substrate, and then phase formation heat treatment and annealing treatment are performed in sequence to obtain bismuth telluride composite thermoelectric long strip.
[0012] Preferably, in step (1), the molar ratio of Bi(NO3)3·5H2O and Na2TeO3 is (1.5~2.5):3.
[0013] Preferably, the concentration of Bi(NO3)3·5H2O in the mixed solution of step (1) is ≤0.03mol / L.
[0014] Preferably, the pH value is adjusted in step (1) by adding sodium hydroxide.
[0015] Preferably, the carbon nanotubes in step (2) are single-walled carbon nanotubes.
[0016] Preferably, the mass ratio of carbon nanotubes used in step (2) to Bi(NO3)3·5H2O used in step (1) is (1-2):5.
[0017] Preferably, the mixing method in step (2) is ultrasonic dispersion in a water bath.
[0018] Preferably, the holding temperature of the phase-forming heat treatment in step (3) is 400-500℃, and the holding time of the phase-forming heat treatment is 2-4h.
[0019] Preferably, the annealing temperature in step (3) is 150-250°C and the annealing time is 30-90 min.
[0020] The present invention provides a bismuth telluride composite thermoelectric long strip prepared by the preparation method described in the above technical solution.
[0021] This invention provides a method for preparing a bismuth telluride composite thermoelectric long band, comprising the following steps: (1) mixing Bi(NO3)3·5H2O and Na2TeO3 with ethylene glycol, and then adjusting the pH value to 7.5-8.5 to obtain a mixed solution; (2) adding carbon nanotubes and ethylene glycol to the mixed solution obtained in step (1), and mixing to obtain a composite thermoelectric film precursor solution; (3) coating the composite thermoelectric film precursor solution obtained in step (2) on a polyimide substrate, and then performing phase formation heat treatment and annealing treatment in sequence to obtain a bismuth telluride composite thermoelectric long band. This invention uses Bi(NO3)3·5H2O and Na2TeO3 as raw materials. A composite thermoelectric thin film precursor solution is first prepared, and then coated onto a polyimide substrate to obtain a large-size thermoelectric thin film. Phase-forming heat treatment allows Bi(NO3)3·5H2O and Na2TeO3 to react and form Bi2Te3. Annealing treatment controls the crystallization state of the material, eliminates structural defects, improves material uniformity, and eliminates internal stress, resulting in a dense Bi2Te3 with small grain size. The results of the embodiments show that the bismuth telluride composite thermoelectric long bands prepared by the method provided by this invention have a size of 50–100 μm, and the Bi2Te3 on the bismuth telluride composite thermoelectric long bands have a layered structure with grain planar sizes in the range of 0.5–1 μm. Attached Figure Description
[0022] Figure 1 This is a SEM image of the bismuth telluride composite thermoelectric long band prepared in Example 1 of the present invention;
[0023] Figure 2 This is a SEM image of the bismuth telluride composite thermoelectric long band prepared in Example 2 of the present invention;
[0024] Figure 3 The relationship between conductivity and temperature in the bismuth telluride composite thermoelectric long band prepared in Example 3 of this invention;
[0025] Figure 4 The Seebeck coefficient in the bismuth telluride composite thermoelectric long band prepared in Example 3 of this invention varies with temperature.
[0026] Figure 5 The power factor of the Bi2Te3 coating in the bismuth telluride composite thermoelectric long band prepared in Example 3 varies with temperature.
[0027] Figure 6 This is a physical diagram of the unwinding device used in the preparation of bismuth telluride composite thermoelectric long strips according to the present invention. Detailed Implementation
[0028] This invention provides a method for preparing bismuth telluride composite thermoelectric long bands, comprising the following steps:
[0029] (1) Mix Bi(NO3)3·5H2O and Na2TeO3 with ethylene glycol, and then adjust the pH value to 7.5-8.5 to obtain a mixed solution;
[0030] (2) Add carbon nanotubes and ethylene glycol to the mixed solution obtained in step (1), and after mixing, obtain a composite thermoelectric film precursor solution;
[0031] (3) The composite thermoelectric thin film precursor liquid obtained in step (2) is coated on a polyimide substrate, and then phase formation heat treatment and annealing treatment are performed in sequence to obtain bismuth telluride composite thermoelectric long strip.
[0032] Unless otherwise specified, all raw materials used in this invention are commercially available products well known to those skilled in the art.
[0033] In this invention, Bi(NO3)3·5H2O and Na2TeO3 are mixed with ethylene glycol, and then the pH value is adjusted to 7.5-8.5 to obtain a mixed solution.
[0034] In this invention, the purity of Bi(NO3)3·5H2O is preferably ≥99%; the molar ratio of Bi(NO3)3·5H2O to Na2TeO3 is preferably (1.5~2.5):3, more preferably 2:3. By controlling the molar ratio of Bi(NO3)3·5H2O and Na2TeO3, this invention can react them to generate the desired Bi2Te3 material, while reducing the content of impurities (i.e., the remaining Bi(NO3)3·5H2O and Na2TeO3 after the reaction), thereby further improving the surface compactness of the bismuth telluride composite strip.
[0035] In this invention, the concentration of Bi(NO3)3·5H2O in the mixed solution is preferably ≤0.03 mol / L, more preferably 0.01–0.03 mol / L, and even more preferably 0.02–3 mol / L. This invention achieves excellent dispersibility by controlling the concentration of Bi(NO3)3·5H2O in ethylene glycol.
[0036] In this invention, the mixing of Bi(NO3)3·5H2O and Na2TeO3 with ethylene glycol is preferably carried out under stirring conditions. In this invention, the stirring rate is preferably 100–300 r / min; the stirring time is preferably 10–30 min, more preferably 10–20 min. By controlling the stirring parameters, this invention enables a more uniform mixing of the components.
[0037] In this invention, the preferred method for adjusting the pH value is by adding sodium hydroxide. There is no particular limitation on the amount of sodium hydroxide added, as long as the pH value of the mixed solution meets the requirements. By controlling the pH value of the mixed solution, this invention facilitates the subsequent reactions.
[0038] After adjusting the pH value to 7.5–8.5, the product after pH adjustment is preferably stirred to obtain a mixed solution. In this invention, the stirring rate is preferably 100–300 r / min; the stirring time is preferably 10–30 min, more preferably 10–20 min. By controlling the stirring parameters, this invention enables the components to be mixed uniformly.
[0039] After obtaining the mixed solution, the present invention adds carbon nanotubes and ethylene glycol to the mixed solution, and after mixing, obtains a composite thermoelectric film precursor solution.
[0040] In this invention, the carbon nanotubes are preferably single-walled carbon nanotubes. This invention does not impose any special limitations on the size of the carbon nanotubes; commercially available products well-known to those skilled in the art can be used.
[0041] In this invention, the preferred mass ratio of carbon nanotubes to Bi(NO3)3·5H2O is (1-2):5, more preferably 1:5. This invention aims to improve the electrical conductivity of Bi2Se3 by adding carbon nanotubes and controlling their dosage.
[0042] In this invention, the preferred volume ratio of ethylene glycol to carbon nanotubes in the composite thermoelectric thin film precursor solution is 3:1. By controlling the amount used, this invention allows the carbon nanotubes to be uniformly dispersed in the solution.
[0043] In this invention, the mixing method is ultrasonic dispersion in a water bath. Preferably, the temperature of the water bath is 25°C; the ultrasonic dispersion time is preferably 1–3 hours, more preferably 2–3 hours. This invention does not impose any specific limitation on the power of the ultrasonic dispersion, which can be determined based on the technical knowledge of those skilled in the art. By using ultrasonic dispersion under water bath conditions, this invention enables a more uniform mixing of the components.
[0044] After obtaining the composite thermoelectric film precursor liquid, the present invention coats the composite thermoelectric film precursor liquid on a polyimide substrate, and then performs phase formation heat treatment and annealing treatment in sequence to obtain bismuth telluride composite thermoelectric long strip.
[0045] In this invention, the polyimide substrate is preferably a flexible polyimide substrate; the length of the polyimide substrate is preferably 50-100m, more preferably 75-100m; and the thickness of the polyimide substrate is preferably 0.5mm.
[0046] In this invention, the preferred method for coating the polyimide substrate with the composite thermoelectric film precursor solution is as follows: The polyimide substrate is mounted on an unwinding device, connected to a winding device via a guide belt, and passes through a rubber trough containing the composite thermoelectric film precursor solution. Then, by adjusting a tension controller, a force of 0.5–2 MPa is applied to the polyimide substrate to tighten and flatten it on the unwinding-winding device. Finally, the belt speed of the polyimide substrate is adjusted to 500–1000 m / h, allowing the substrate to pass through the composite thermoelectric film precursor solution in the rubber trough, thus immersing the polyimide substrate in the composite thermoelectric film precursor solution. This method ensures uniform coating of the composite thermoelectric film precursor solution onto the polyimide substrate, preventing any omissions.
[0047] In this invention, the coating thickness of the composite thermoelectric thin film precursor solution on the polyimide substrate is preferably 100 nm to 100 μm. By controlling the subsequent processes of the composite thermoelectric thin film precursor solution, this invention ensures the preparation of Bi2Te3 with sufficient thickness.
[0048] In this invention, the phase-forming heat treatment is preferably carried out in a vacuum furnace.
[0049] Preferably, the vacuum furnace is pretreated before the phase-forming heat treatment. In this invention, the pretreatment is preferably performed by: turning on the mechanical pump and evacuating to a vacuum level of 1×10⁻⁶. -2 Pa ~ 1×10 - The pressure is set to 1 Pa, and then 200–400 sccm of high-purity argon gas is introduced to adjust the working pressure to 1–10 Pa. This invention removes air from the vacuum furnace through pretreatment, thus preventing air from affecting the reaction process.
[0050] In this invention, the holding temperature of the phase-forming heat treatment is preferably 400–500°C, more preferably 450–500°C; the holding time of the phase-forming heat treatment is preferably 2–4 hours, more preferably 3–4 hours. By controlling the parameters of the phase-forming heat treatment, this invention can further promote the reaction to form Bi2Te3.
[0051] After the phase-forming heat treatment is completed, the product of the phase-forming heat treatment is preferably cooled to the annealing temperature for annealing treatment. In this invention, the cooling rate is preferably 5°C / min.
[0052] In this invention, the annealing temperature is preferably 150–250°C, more preferably 200–250°C; the annealing time is preferably 30 min. By controlling the parameters of the annealing process, this invention can control the crystallization state of the material, eliminate structural defects, improve material uniformity, and eliminate internal stress.
[0053] This invention uses Bi(NO3)3·5H2O and Na2TeO3 as raw materials. By first preparing a composite thermoelectric thin film precursor solution and then coating it on a polyimide substrate, a large-size thermoelectric thin film can be prepared. Through phase formation heat treatment, Bi(NO3)3·5H2O and Na2TeO3 can react to form Bi2Te3, while annealing treatment can control the crystallization state of the material, eliminate structural defects, improve material uniformity, and eliminate internal stress, thereby obtaining Bi2Te3 with good density and small grain size.
[0054] This invention provides a bismuth telluride composite thermoelectric long strip prepared by the preparation method described above. The bismuth telluride composite thermoelectric long strip provided by this invention has a size of 50-100 μm, and the Bi2Te3 on the bismuth telluride composite thermoelectric long strip has a layered structure with a grain planar size in the range of 0.5-1 μm and a thickness of 500 nm-10 μm.
[0055] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0056] Example 1
[0057] A method for preparing a bismuth telluride composite thermoelectric long band comprises the following steps:
[0058] (1) Bi(NO3)3·5H2O with a purity of 99% and Na2TeO3 were mixed with ethylene glycol at a molar ratio of 2:3 and stirred for 10 min. Then, sodium hydroxide was added to adjust the pH value to 7.5, and stirring was continued for 10 min to obtain a mixed solution. The concentration of Bi(NO3)3·5H2O in the mixed solution was 0.03 mol / L. The stirring rate was 200 r / min.
[0059] (2) Add carbon nanotubes and ethylene glycol to the mixed solution obtained in step (1), and then ultrasonically disperse in a water bath for 1 hour to obtain a composite thermoelectric film precursor solution; the mass ratio of the amount of carbon nanotubes to Bi(NO3)3·5H2O is 1:5; the volume ratio of ethylene glycol to carbon nanotubes in the composite thermoelectric film precursor solution is 3:1.
[0060] (3) A 50m long and 0.5mm thick polyimide flexible substrate is mounted on an unwinding device. The polyimide substrate is connected to a winding device via a guide belt and passes through a rubber tank containing a composite thermoelectric film precursor solution. Then, by adjusting the tension controller, a force of 0.5MPa is applied to the polyimide substrate to tighten and flatten it on the unwinding-winding device. Finally, the conveyor speed of the polyimide substrate is adjusted to 500m / h so that the polyimide substrate passes through the composite thermoelectric film precursor solution in the rubber tank. A 500nm layer of composite thermoelectric film precursor solution is applied to the polyimide substrate. Then, the polyimide flexible substrate is placed in a pre-treated vacuum furnace for phase formation heat treatment and annealing treatment to obtain a bismuth telluride composite thermoelectric long strip. The pre-treatment method is as follows: turn on the mechanical pump and evacuate to 1×10 -2 Pa, then 200 sccm of high-purity argon gas is introduced, and the working pressure is adjusted to 1 Pa; the holding temperature of the phase-forming heat treatment is 400℃, and the holding time of the phase-forming heat treatment is 2h; the cooling rate of the phase-forming heat-treated product to the annealing temperature is 5℃ / min; the annealing temperature is 150℃, and the annealing time is 30min.
[0061] The surface morphology of the bismuth telluride composite thermoelectric ribbon prepared in Example 1 was observed using scanning electron microscopy, and the results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the Bi2Te3 on the bismuth telluride composite thermoelectric long band has a layered structure with grain planar size in the range of 0.5 to 1 μm.
[0062] Example 2
[0063] A method for preparing a bismuth telluride composite thermoelectric long band comprises the following steps:
[0064] (1) Bi(NO3)3·5H2O with a purity of 99% and Na2TeO3 were mixed with ethylene glycol at a molar ratio of 2:3 and stirred for 20 min. Then, sodium hydroxide was added to adjust the pH value to 8.0, and stirring was continued for 20 min to obtain a mixed solution. The concentration of Bi(NO3)3·5H2O in the mixed solution was 0.03 mol / L. The stirring rate was 200 r / min.
[0065] (2) Add carbon nanotubes and ethylene glycol to the mixed solution obtained in step (1), and then ultrasonically disperse in a water bath for 2 hours to obtain a composite thermoelectric film precursor solution; the mass ratio of the amount of carbon nanotubes to Bi(NO3)3·5H2O is 1:5; the volume ratio of ethylene glycol to carbon nanotubes in the composite thermoelectric film precursor solution is 3:1.
[0066] (3) A 75m long and 0.5mm thick polyimide flexible substrate is mounted on an unwinding device. The polyimide substrate is connected to a winding device via a guide belt and passes through a rubber tank containing a composite thermoelectric film precursor solution. Then, by adjusting the tension controller, a force of 1MPa is applied to the polyimide substrate to tighten and flatten it on the unwinding-winding device. Finally, the conveyor speed of the polyimide substrate is adjusted to 750m / h so that the polyimide substrate passes through the composite thermoelectric film precursor solution in the rubber tank. A 5μm layer of composite thermoelectric film precursor solution is applied to the polyimide substrate. Then, the polyimide flexible substrate is placed in a pre-treated vacuum furnace for phase formation heat treatment and annealing treatment to obtain a bismuth telluride composite thermoelectric long strip. The pre-treatment method is as follows: turn on the mechanical pump and evacuate to 5×10 -1 Pa, then 300 sccm of high-purity argon gas is introduced, and the working pressure is adjusted to 5 Pa; the holding temperature of the phase-forming heat treatment is 450℃, and the holding time of the phase-forming heat treatment is 3h; the cooling rate of the phase-forming heat-treated product to the annealing temperature is 5℃ / min; the annealing temperature is 200℃, and the annealing time is 30min.
[0067] The surface morphology of the bismuth telluride composite thermoelectric ribbon prepared in Example 2 was observed using a scanning electron microscope, and the results are as follows: Figure 2 As shown. By Figure 2 It can be seen that the Bi2Te3 on the bismuth telluride composite thermoelectric long band has a layered structure with grain planar size in the range of 0.5 to 1 μm.
[0068] Example 3
[0069] A method for preparing a bismuth telluride composite thermoelectric long band comprises the following steps:
[0070] (1) Bi(NO3)3·5H2O with a purity of 99% and Na2TeO3 were mixed with ethylene glycol at a molar ratio of 2:3 and stirred for 30 min. Then, sodium hydroxide was added to adjust the pH value to 8.5, and stirring was continued for 30 min to obtain a mixed solution. The concentration of Bi(NO3)3·5H2O in the mixed solution was 0.03 mol / L. The stirring rate was 200 r / min.
[0071] (2) Add carbon nanotubes and ethylene glycol to the mixed solution obtained in step (1), and then ultrasonically disperse in a water bath for 3 hours to obtain a composite thermoelectric film precursor solution; the mass ratio of the amount of carbon nanotubes to Bi(NO3)3·5H2O is 1:5; the volume ratio of ethylene glycol to carbon nanotubes in the composite thermoelectric film precursor solution is 3:1.
[0072] (3) A 100m long and 0.5mm thick polyimide flexible substrate is mounted on an unwinding device. The polyimide substrate is connected to a winding device via a guide belt and passes through a rubber tank containing a composite thermoelectric film precursor solution. Then, by adjusting the tension controller, a force of 2MPa is applied to the polyimide substrate to tighten and flatten it on the unwinding-winding device. Finally, the conveyor speed of the polyimide substrate is adjusted to 1000m / h so that the polyimide substrate passes through the composite thermoelectric film precursor solution in the rubber tank. A 10μm layer of composite thermoelectric film precursor solution is applied to the polyimide substrate. Then, the polyimide flexible substrate is placed in a pre-treated vacuum furnace for phase formation heat treatment and annealing treatment to obtain a bismuth telluride composite thermoelectric long strip. The pre-treatment method is as follows: turn on the mechanical pump and evacuate to 1×10 -1 Pa, then 400 sccm of high-purity argon gas is introduced, and the working pressure is adjusted to 10 Pa; the holding temperature of the phase-forming heat treatment is 500℃, and the holding time of the phase-forming heat treatment is 4h; the cooling rate of the phase-forming heat-treated product to the annealing temperature is 5℃ / min; the annealing temperature is 250℃, and the annealing time is 30min.
[0073] The conductivity of the bismuth telluride composite thermoelectric long band prepared in Example 3 as a function of temperature was tested using ZEM-3, and the results are as follows: Figure 3 As shown. By Figure 3 It can be seen that the room temperature conductivity (σ) is approximately 730 S·cm. -1 As temperature increases, conductivity gradually increases.
[0074] The Seebeck (S) coefficient of the bismuth telluride composite thermoelectric long band prepared in Example 3 was tested as a function of temperature using the ZEM-3 thermoelectric property evaluation device from Japan Vacuum Technology Corporation. The results are as follows: Figure 4 As shown. By Figure 4 It can be seen that the Seebeck coefficient is negative, indicating that the Bi2Te3 coating is an n-type material with electron-dominated carrier transport; the Seebeck coefficient increases with increasing temperature, reaching a maximum value of approximately -74 μV·K. -1 The electrical conductivity and Seebeck coefficient of a material are closely related to the carrier concentration. The electrical conductivity (σ) is directly proportional to the carrier concentration and mobility, but the Seebeck coefficient is inversely proportional to the carrier concentration. Therefore, controlling the carrier concentration and mobility of a material can optimize its electrical performance.
[0075] The power factor of the Bi2Te3 coating in the bismuth telluride composite thermoelectric long band prepared in Example 3 was tested as a function of temperature, and the results are as follows: Figure 5 As shown. By Figure 5It can be seen that the power factor is a comprehensive index that can evaluate the electrical performance of materials, and it increases with increasing temperature, from 277 μW / m². -1 ·K -2 Increased to 492 μWm -1 ·K -2 .
[0076] A physical diagram of the unwinding device used in the production of the bismuth telluride composite thermoelectric long strip of this invention is shown below. Figure 6 As shown.
[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a bismuth telluride composite thermoelectric long band, comprising the following steps: (1) Mix Bi(NO3)3·5H2O and Na2TeO3 with ethylene glycol, and then adjust the pH value to 7.5~8.5 to obtain a mixed solution; (2) Add carbon nanotubes and ethylene glycol to the mixed solution obtained in step (1), and mix to obtain a composite thermoelectric film precursor solution; (3) Coating the composite thermoelectric thin film precursor liquid obtained in step (2) onto a polyimide substrate, and then performing phase formation heat treatment and annealing treatment in sequence to obtain bismuth telluride composite thermoelectric long strip; The mass ratio of carbon nanotubes used in step (2) to Bi(NO3)3·5H2O used in step (1) is (1~2):5; The holding temperature for phase formation heat treatment in step (3) is 400~500℃, and the holding time for phase formation heat treatment is 2~4h; The annealing temperature in step (3) is 150~250℃ and the annealing time is 30~90min.
2. The production method according to claim 1, characterized by, In step (1), the molar ratio of Bi(NO3)3·5H2O and Na2TeO3 is (1.5~2.5):
3.
3. The preparation method according to claim 1, characterized in that, The concentration of Bi(NO3)3·5H2O in the mixed solution in step (1) is ≤0.03mol / L.
4. The preparation method according to claim 1, characterized in that, In step (1), the pH value is adjusted by adding sodium hydroxide.
5. The preparation method according to claim 1, characterized in that, In step (2), the carbon nanotubes are single-walled carbon nanotubes.
6. The preparation method according to claim 1, characterized in that, The mixing method in step (2) is ultrasonic dispersion in a water bath.
7. The bismuth telluride composite thermoelectric long strip prepared by the preparation method according to any one of claims 1 to 6.