A bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof

Abstract

The application discloses a kind of tellurium bismuth-based thermoelectric material ink for 3D printing and preparation method thereof, comprising: tellurium bismuth-based material powder, solvent, crosslinking agent.Tellurium bismuth-based thermoelectric material powder, solvent, crosslinking agent are mixed by mechanical stirring method and ball milling method, obtain the tellurium bismuth-based thermoelectric material ink for 3D printing.The particle size of tellurium bismuth-based thermoelectric material powder needs to be controlled below 30 μm, and the content of tellurium bismuth-based thermoelectric material powder is 50-80wt%, and the mass ratio of crosslinking agent is 1-5wt%.According to different printing requirements, the viscosity, storage modulus, loss modulus and other rheological properties of tellurium bismuth-based thermoelectric material ink can be adjusted by the solid content of thermoelectric material, the component ratio of solvent and crosslinking agent.The preparation process of the application method is simple and convenient, and has the potential of large-scale production.The tellurium bismuth-based thermoelectric material ink prepared by the application can be used for 3D printing design various types of thermoelectric devices.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermoelectric material preparation, and more specifically, the present invention relates to a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. Background Art

[0002] Thermoelectric conversion technology can convert thermal energy into electrical energy through the Seebeck effect, and can also convert electrical energy into thermal energy through the Peltier effect. This conversion method is characterized by small size, light weight, no mechanical movement, no noise, no pollution, and long life. It has wide application value in steel plant waste heat recovery, solid-state refrigeration, Internet of Things, CUP cooling and other fields.

[0003] Bismuth telluride-based thermoelectric materials exhibit excellent thermoelectric performance at low temperatures and are currently among the most promising thermoelectric materials for large-scale application. However, the preparation of traditional bismuth telluride-based thermoelectric materials and thermoelectric devices suffers from drawbacks such as high material requirements, complex processes, poor reliability, and high costs, hindering large-scale production and practical applications, and severely restricting the development of thermoelectric conversion technology. Therefore, improved manufacturing processes are urgently needed to enable the large-scale production of thermoelectric conversion systems.

[0004] Ink direct writing technology integrates multiple disciplines such as physics, chemistry, optics, materials, electromechanics, and software engineering. The cross-integration of various disciplines has formed a unique high-end manufacturing technology that can selectively control or change the physical state and properties of materials from multiple scales and dimensions, becoming a cutting-edge hotspot in the manufacturing field. This technology can deposit ink on a substrate according to a pre-designed structure, and through the control of factors such as airflow, movement speed, and spacing, it can precisely achieve structural molding from point to line to surface, from part to whole. Unlike traditional subtractive manufacturing, this additive manufacturing process is simple to operate, has no material waste, and can form various complex structures in one go. It undoubtedly has the potential to solve the difficulties in the manufacture of thermoelectric materials and devices. Applying ink direct writing to thermoelectric conversion technology can print small and micro devices for flexible wearable electronic components, as well as large and complex structure devices for irregular surfaces.

[0005] In the direct writing technology of thermoelectric material ink, the preparation of printing ink is both the focus and the difficulty. First of all, the powder particle size of the ink must have a reasonable size distribution, otherwise it is easy to clog the nozzle or cause the product structure to be unstable. Secondly, the types and proportions of solvents and cross-linking agents in the ink should be minimized and easy to remove in post-processing. At the same time, the ink must also have low toxicity and high stability. However, there is currently a lack of systematic research on the preparation of inks both internationally and domestically, especially for the relevant reports on high-performance lead telluride thermoelectric materials in the low-temperature range, which are still at the basic research stage. Summary of the Invention

[0006] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0007] To achieve these objectives and other advantages according to the present invention, a bismuth telluride-based thermoelectric material ink for 3D printing is provided, comprising: bismuth telluride-based thermoelectric material powder, a solvent, and a cross-linking agent.

[0008] Preferably, the mass proportion of the bismuth telluride-based thermoelectric material powder is 50-80 wt %, the mass proportion of the cross-linking agent is 1-5 wt %, and the mass proportion of the solvent is 20-50 wt %.

[0009] Preferably, the bismuth telluride-based thermoelectric material powder is Bi2Te 2.7 Se 0.3 Thermoelectric material powder, the particle size of the bismuth telluride-based thermoelectric material powder is less than 30 μm, wherein the proportion of particles with a diameter of more than 1 μm cannot be less than 90%, and the proportion of particles with a diameter of less than 10 μm cannot be less than 50%.

[0010] Preferably, the solvent is deionized water, ethanol, glycerol, N,N-dimethylformamide or a mixture thereof.

[0011] Preferably, the cross-linking agent is one or a mixture of polyacrylic acid, polyethyleneimine, polyvinyl pyrrolidone, and methyl cellulose.

[0012] A method for preparing bismuth telluride-based thermoelectric material ink for 3D printing comprises: mixing bismuth telluride-based thermoelectric material powder, a solvent, and a cross-linking agent through mechanical stirring and ball milling to obtain the bismuth telluride-based thermoelectric material ink for 3D printing.

[0013] Preferably, the method comprises the following steps:

[0014] Step 1: Prepare bismuth telluride-based thermoelectric material powder, wherein the powder particle size is less than 30 μm, wherein the proportion of particles larger than 1 μm is not less than 90%, and the proportion of particles smaller than 10 μm is not less than 50%;

[0015] Step 2: Prepare bismuth telluride-based thermoelectric material powder, solvent, and cross-linking agent according to the component ratio, wherein the solid content of the thermoelectric material powder is 50-80wt%, the mass proportion of the cross-linking agent is 1-5wt%, and the mass proportion of the solvent is 20-50wt%;

[0016] Step 3. The bismuth telluride-based thermoelectric material powder, solvent, and cross-linking agent are mixed by mechanical stirring and ball milling to obtain a bismuth telluride-based thermoelectric material ink for 3D printing; wherein, the specific method of mixing the bismuth telluride-based thermoelectric material powder, solvent, and cross-linking agent by mechanical stirring and ball milling includes: mixing the cross-linking agent with the solvent, the mechanical stirring speed is 100-400 r / min, and the stirring time is 0.5-2h to obtain a solution; then the obtained solution is mixed with the bismuth telluride-based thermoelectric material powder by ball milling, and the specific parameters are: setting the ball-to-material ratio to 1:1, the clockwise rotation speed is 200-400 r / min, and the ball milling is stopped for 5 minutes every 10 minutes; counterclockwise, the rotation speed is 200-400 r / min, and the ball milling is stopped for 5 minutes every 10 minutes; the total time is 120-360 minutes.

[0017] Preferably, in the step 1, a thickener is added to the bismuth telluride-based thermoelectric material powder to adjust the rheological properties and fluid behavior, and the mass of the thickener accounts for 0.1 to 5 wt% of the mass of the bismuth telluride-based thermoelectric material powder;

[0018] The thickener includes but is not limited to: one or more of polyvinyl pyrrolidone, methyl cellulose, gelatin, β-cyclodextrin, hydroxyethyl cellulose, and chitosan.

[0019] Preferably, in step 2, an electrolyte solution is added to the solvent to adjust the pH value of the solvent and regulate the rheological properties and fluid behavior, and the volume percentage of the electrolyte solution to the solvent is 0.01% to 1%:1.

[0020] The electrolyte solution includes but is not limited to: one or more of ammonia water, sodium hydroxide, sodium bicarbonate, sodium carbonate, sulfuric acid, hydrochloric acid, and nitric acid.

[0021] An application of bismuth telluride-based thermoelectric material ink for 3D printing, which is applied to 3D printing thermoelectric devices. The specific application method includes: using an ink direct writing 3D printer to print the bismuth telluride-based thermoelectric material ink according to a preset three-dimensional model to obtain a thermoelectric device. During printing, the gas flow rate is set to 0.01-1 mL / min, and the platform movement speed is set to 1-10 mm / s, which is conducive to the smooth extrusion and molding of the bismuth telluride-based thermoelectric material ink.

[0022] In order to further control the viscosity of bismuth telluride-based thermoelectric material ink and improve the 3D printing performance of bismuth telluride-based thermoelectric material ink, the bismuth telluride-based thermoelectric material powder is pre-dispersed and ball-milled. The specific methods include:

[0023] S1. Add bismuth telluride-based thermoelectric material powder to deionized water, and ultrasonically disperse it at a frequency of 40 to 80 kHz for 20 to 40 minutes to obtain a suspension; add 1 mol / L hydrochloric acid to the suspension to adjust the pH of the suspension to 4 to 5; then add polyethylene glycol-400 to the suspension, ultrasonically disperse it at a frequency of 80 to 100 kHz for 20 to 40 minutes, and let it stand for 24 to 36 hours; filter the stationary suspension, wash it with anhydrous ethanol several times, and dry it to obtain a dispersed powder; wherein the amount ratio of bismuth telluride-based thermoelectric material powder, polyethylene glycol-400, and deionized water is 2 to 10 g: 0.2 to 5 mL: 250 to 500 mL, and the average relative molecular weight of the polyethylene glycol-400 used is ≤300 g / mol and the viscosity is ≤80 mPa·s;

[0024] S2. The dispersed powder is placed in a ball mill with a ball-to-material ratio of 3:1. Ethyl acetate is added to the ball mill as a dispersant, with the amount of ethyl acetate being 0.2-1 wt % of the dispersed powder. The ball mill speed is 600-800 r / min and the ball milling time is 20-60 min. After ball milling, the powder is separated, washed, and dried to obtain a pre-dispersed and ball-milled bismuth telluride-based thermoelectric material powder.

[0025] The present invention has at least the following beneficial effects:

[0026] 1) The present invention can prepare thermoelectric material ink from bismuth telluride-based thermoelectric materials through mechanical stirring and ball milling, providing a method for scalable production of thermoelectric material ink with a simple process. The ink preparation process is simple, has low toxicity, high stability, high solid content, and easy removal of solvents and cross-linking agents, effectively ensuring the thermoelectric performance of the material.

[0027] 2) The bismuth telluride-based thermoelectric ink prepared by this invention for direct-write 3D printing offers stable properties and excellent quality. The ink's rheological properties, such as viscosity, storage modulus, and loss modulus, can be adjusted to meet diverse printing requirements by adjusting the solid content of the thermoelectric material and the ratio of solvent to crosslinker, resulting in a wide range of applications.

[0028] 3) The present invention further reduces the particle size of the bismuth telluride-based thermoelectric material powder by dispersing and ball milling the dried bismuth telluride-based thermoelectric material powder, making the particle size distribution of the bismuth telluride-based thermoelectric material powder more concentrated, thereby facilitating further regulation of the viscosity of the bismuth telluride-based thermoelectric material ink; wherein, during the dispersion pretreatment, the pH of the bismuth telluride-based thermoelectric material powder suspension is adjusted to 4-5, and polyethylene glycol-400 with an average relative molecular weight of ≤300 g / mol and a viscosity of ≤80 mPa·s is used as a dispersant. The results show that polyethylene glycol-400 with such viscosity and average relative molecular weight effectively avoids the agglomeration of the bismuth telluride-based thermoelectric material powder and achieves the dispersion of the bismuth telluride-based thermoelectric material powder; subsequently, ethyl acetate is used as a dispersant to ball mill the bismuth telluride-based thermoelectric material powder, thereby reducing the particle size of the bismuth telluride-based thermoelectric material powder and making the particle size distribution of the bismuth telluride-based thermoelectric material powder more concentrated.

[0029] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Bi2Te obtained in Example 1 2.7 Se 0.3 X-ray diffraction pattern (XRD) of thermoelectric material powder;

[0031] Figure 2 Bi2Te obtained in Example 1 2.7 Se 0.3 Particle size distribution of thermoelectric material powder;

[0032] Figure 3 Bi2Te obtained in Example 1 2.7 Se 0.3 The finished product of the thermoelectric material ink: the left picture shows the state immediately after preparation, and the right picture shows the state after seven days of rest.

[0033] Figure 4 Bi2Te obtained in Example 1 2.7 Se 0.3 The relationship between the storage modulus (G′) and loss modulus (G″) of thermoelectric material ink at different shear rates;

[0034] Figure 5 Bi2Te obtained in Example 1 2.7 Se 0.3 The relationship between the viscosity η of the thermoelectric material ink and the shear rate;

[0035] Figure 6 Bi2Te obtained in Example 2 2.7 Se0.3 The relationship between the viscosity η of the thermoelectric material ink and the shear rate;

[0036] Figure 7 Bi2Te obtained in Example 3 2.7 Se 0.3 The relationship between the viscosity η of the thermoelectric material ink and the shear rate;

[0037] Figure 8 Bi2Te obtained in Example 4 2.7 Se 0.3 Graph showing the relationship between the viscosity η of thermoelectric material ink and shear rate. DETAILED DESCRIPTION

[0038] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0039] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0040] Example 1

[0041] This embodiment provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof, comprising the following steps:

[0042] Step 1: Weigh Bi powder, Te powder, and Se powder in an agate mortar at an element ratio of 2:2.3:0.3, grind them for 30 minutes, and mix the powders evenly.

[0043] The ground powder was transferred into a ball mill with a ball-to-material ratio of 10:1 and a volume ratio of alcohol to the ball mill of 1:3. The specific parameters of the ball milling process were: clockwise, 400 r / min, 15 minutes of pause every 20 minutes; counterclockwise, 400 r / min, 15 minutes of pause every 20 minutes; the total time was 1200 minutes to obtain Bi2Te 2.7 Se 0.3 Thermoelectric material powder;

[0044] The wet-ground Bi2Te 2.7 Se 0.3 The thermoelectric material powder was transferred to a vacuum drying oven and dried until the anhydrous ethanol was completely evaporated, and then passed through a 400-mesh sieve for later use;

[0045] Step 2: Add 0.8 g of cross-linking agent polyacrylic acid and 1.6 g of polyethyleneimine to 50 g of deionized water (solvent), and mix by mechanical stirring to obtain a mixed solution; the specific parameters of the mechanical stirring process are: 200 r / min, and the total time is 60 minutes;

[0046] Step 3: Weigh the prepared Bi2Te 2.7 Se 0.3 80g of thermoelectric material powder was transferred into a ball mill, and the mixed solution was poured into the ball mill for mixing. The specific parameters were set as follows: set the ball-to-material ratio to 1:1, clockwise rotation speed of 300r / min, and stop for 5 minutes every 10 minutes; counterclockwise rotation speed of 300r / min, and stop for 5 minutes every 10 minutes, for a total of 180 minutes; the mixed solution obtained after the ball milling was Bi2Te3O3 for 3D printing. 2.7 Se 0.3 Thermoelectric material ink.

[0047] from Figure 1 It can be seen that the Bi2Te prepared in step 1 of this embodiment 2.7 Se 0.3 The corresponding diffraction peaks and peak diffraction intensities appear at each crystal plane position in the thermoelectric material powder, showing a single-phase behavior, indicating that the main phase is Bi2Te 2.7 Se 0.3 And the prepared thermoelectric material has high quality.

[0048] from Figure 2 It can be seen that the Bi2Te after drying in step 1 of this embodiment 2.7 Se 0.3 The particle size of the thermoelectric material powder is mainly distributed between 5 and 15 μm, which meets the predetermined experimental requirements.

[0049] from Figure 3 It can be seen that the Bi2Te prepared in step 3 of this embodiment 2.7 Se 0.3 The performance of the thermoelectric material ink is stable, and no precipitation or stratification occurs after seven days of storage.

[0050] Figure 4 Bi2Te 2.7 Se 0.3 The rheological properties of the thermoelectric material ink, namely the relationship between the storage modulus (G′) and the loss modulus (G″) as a function of shear rate, show that G′ is always greater than G″, indicating that Bi2Te 2.7 Se 0.3 Thermoelectric material ink has elastic behavior, which is conducive to maintaining the printed shape.

[0051] Figure 5 Bi2Te prepared in this example 2.7 Se 0.3 The rheological properties of thermoelectric material ink, that is, the relationship between viscosity η and shear rate, show that as the shear rate increases, the viscosity of the ink decreases continuously, showing shear thinning characteristics, which is conducive to ink extrusion. -1 When Bi2Te 2.7 Se 0.3The viscosity of the thermoelectric material ink is 300.5 Pa·s.

[0052] Example 2

[0053] This embodiment provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. The difference from Example 1 is that the Bi2Te in step 1 of this embodiment is 2.7 Se 0.3 Polyvinyl pyrrolidone was added to the thermoelectric material powder as a thickener. The amount of polyvinyl pyrrolidone used was 2.2 g. The methods and parameters of the remaining steps of this embodiment were the same as those in Example 1.

[0054] Figure 6 Bi2Te prepared in this example 2.7 Se 0.3 Graph showing the relationship between the viscosity η of thermoelectric material ink and shear rate.

[0055] Example 3

[0056] This embodiment provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. The difference from Example 1 is that ammonia water is added to the deionized water in step 2 of this embodiment as an electrolyte solution, and the amount of ammonia water used is 0.5 g. The methods and parameters of the remaining steps of this embodiment are the same as those in Example 1.

[0057] Figure 7 Bi2Te prepared in this example 2.7 Se 0.3 Graph showing the relationship between the viscosity η of thermoelectric material ink and shear rate.

[0058] Example 4

[0059] This embodiment provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. The difference from Example 1 is that the Bi2Te in step 1 of this embodiment is 2.7 Se 0.3 Polyvinyl pyrrolidone was added to the thermoelectric material powder as a thickener, and the amount of polyvinyl pyrrolidone was 2.2 g. 0.5 g of ammonia water was added to the deionized water in step 2 as an electrolyte solution. The methods and parameters of the remaining steps of this embodiment were the same as those in embodiment 1.

[0060] Figure 8 Bi2Te prepared in this example 2.7 Se 0.3 Graph showing the relationship between the viscosity η of thermoelectric material ink and shear rate.

[0061] Example 5

[0062] This embodiment provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. Compared with Example 1, the difference in this embodiment is that in step one of Bi2Te 2.7 Se 0.3 After the thermoelectric material powder is dried, Bi2Te 2.7 Se 0.3 Thermoelectric material powders are pre-dispersed and ball-milled. The specific methods include:

[0063] S1, 5g Bi2Te 2.7 Se 0.3 Thermoelectric material powder was added to 250 mL of deionized water and ultrasonically dispersed at a frequency of 40 kHz for 30 minutes to obtain a suspension; 1 mol / L hydrochloric acid was added to the suspension to adjust the pH of the suspension to 5; 2 mL of polyethylene glycol-400 was then added to the suspension, ultrasonically dispersed at a frequency of 80 kHz for 40 minutes, and allowed to stand for 24 hours; the stationary suspension was filtered, washed multiple times with anhydrous ethanol, and dried to obtain a dispersed powder; wherein the polyethylene glycol-400 used had an average relative molecular weight of 280 g / mol and a viscosity of 60 mPa·s;

[0064] S2. The dispersed powder is placed in a ball mill with a ball-to-material ratio of 3:1. Ethyl acetate is added to the ball mill as a dispersant. The amount of ethyl acetate is 0.5 wt % of the dispersed powder. The ball mill speed is 600 r / min and the ball milling time is 20 min. After ball milling, the powder is separated, washed, and dried to obtain a pre-dispersed and ball-milled bismuth telluride-based thermoelectric material powder.

[0065] The methods and process parameters of step 2 and step 3 of this embodiment are the same as those of embodiment 1.

[0066] When the shear rate is 1s -1 When Bi2Te prepared in this example 2.7 Se 0.3 The viscosity of the thermoelectric material ink is 210.4 Pa·s. 2.7 Se 0.3 Thermoelectric material powders are mainly distributed between 3 and 8 μm. Compared with Example 1, Bi2Te 2.7 Se 0.3 The particle size distribution of thermoelectric material powder is more concentrated.

[0067] Example 6

[0068] This embodiment provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. Compared with Example 1, the difference in this embodiment is that in step one of Bi2Te 2.7 Se 0.3After the thermoelectric material powder is dried, Bi2Te 2.7 Se 0.3 Thermoelectric material powders are pre-dispersed and ball-milled. The specific methods include:

[0069] S1, 10g Bi2Te 2.7 Se 0.3 Thermoelectric material powder was added to 300 mL of deionized water and ultrasonically dispersed at a frequency of 60 kHz for 40 minutes to obtain a suspension; 1 mol / L hydrochloric acid was added to the suspension to adjust the pH of the suspension to 5; 5 mL of polyethylene glycol-400 was then added to the suspension, ultrasonically dispersed at a frequency of 80 kHz for 40 minutes, and allowed to stand for 36 hours; the stationary suspension was filtered, washed multiple times with anhydrous ethanol, and dried to obtain a dispersed powder; wherein the polyethylene glycol-400 used had an average relative molecular weight of 300 g / mol and a viscosity of 80 mPa·s;

[0070] S2. The dispersed powder was placed in a ball mill with a ball-to-material ratio of 3:1. Ethyl acetate was added to the ball mill as a dispersant. The amount of ethyl acetate was 0.5 wt % of the dispersed powder. The ball mill speed was 800 r / min and the ball milling time was 20 min. After ball milling, the pre-dispersed and ball-milled Bi2Te3 was obtained by separation, washing and drying. 2.7 Se 0.3 Thermoelectric material powder.

[0071] The methods and process parameters of step 2 and step 3 of this embodiment are the same as those of embodiment 1.

[0072] When the shear rate is 1s -1 When Bi2Te prepared in this example 2.7 Se 0.3 The viscosity of the thermoelectric material ink is 200.8 Pa·s. 2.7 Se 0.3 Thermoelectric material powders are mainly distributed between 4 and 9 μm. Compared with Example 1, Bi2Te 2.7 Se 0.3 The particle size distribution of thermoelectric material powder is more concentrated.

[0073] Comparative Example 1

[0074] This comparative example provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. Compared with Example 1, the difference between this comparative example and Bi2Te 2.7 Se 0.3 The thermoelectric material powder was sieved through a 400-mesh sieve, and the sieved Bi2Te 2.7 Se 0.3Thermoelectric material powder is pre-dispersed. The specific methods include:

[0075] 5g Bi2Te 2.7 Se 0.3 Thermoelectric material powder was added to 250 mL of deionized water and ultrasonically dispersed at a frequency of 40 kHz for 30 minutes to obtain a suspension; 1 mol / L hydrochloric acid was added to the suspension to adjust the pH of the suspension to 5; 2 mL of polyethylene glycol-400 was then added to the suspension, ultrasonically dispersed at a frequency of 80 kHz for 40 minutes, and allowed to stand for 24 hours; the stationary suspension was filtered, washed with anhydrous ethanol several times, and dried to obtain pre-dispersed Bi2Te 2.7 Se 0.3 Thermoelectric material powder; wherein the polyethylene glycol-400 used has an average relative molecular weight of 280 g / mol and a viscosity of 60 mPa·s; then the pre-dispersed Bi2Te 2.7 Se 0.3 The thermoelectric material powder and the mixed solution prepared in step 2 of Example 1 were ball-milled in step 3, and the methods and process parameters of steps 2 and 3 were the same as those in Example 1 to obtain Bi2Te3 for 3D printing. 2.7 Se 0.3 Thermoelectric material ink.

[0076] When the shear rate is 1s -1 When Bi2Te prepared in this comparative example 2.7 Se 0.3 The viscosity of the thermoelectric material ink is 340.6 Pa·s. 2.7 Se 0.3 Thermoelectric material powders are mainly distributed between 5 and 15 μm.

[0077] Comparative Example 2

[0078] This comparative example provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. Compared with Example 1, the difference between this comparative example and Bi2Te 2.7 Se 0.3 The thermoelectric material powder was sieved through a 400-mesh sieve, and the sieved Bi2Te 2.7 Se 0.3 The thermoelectric material powder is pre-milled, and the specific method includes:

[0079] Bi2Te 2.7 Se 0.3 Thermoelectric material powder is placed in a ball mill with a ball-to-material ratio of 3:1. Ethyl acetate is added to the ball mill as a dispersant. The amount of ethyl acetate is Bi2Te 2.7 Se 0.30.5wt% of thermoelectric material powder was milled at a speed of 800r / min for 20min. After milling, the pre-milled Bi2Te was obtained by separation, washing and drying. 2.7 Se 0.3 Thermoelectric material powder. The method and process parameters of step 2 and step 3 of this comparative example are the same as those of embodiment 1.

[0080] When the shear rate is 1s -1 When Bi2Te prepared in this comparative example 2.7 Se 0.3 The viscosity of the thermoelectric material ink is 608.2 Pa·s. 2.7 Se 0.3 Thermoelectric material powders are mainly distributed between 4 and 11 μm.

[0081] Comparative Example 3

[0082] This comparative example provides a bismuth telluride-based thermoelectric material ink for 3D printing and a preparation method thereof. Compared with Example 5, the average relative molecular weight of polyethylene glycol-400 used in S1 is 400 g / mol and the viscosity is 90 mPa·s. The methods and process parameters of the remaining steps of this example are the same as those in Example 5.

[0083] When the shear rate is 1s -1 When Bi2Te prepared in this comparative example 2.7 Se 0.3 The viscosity of the thermoelectric material ink is 402.7 Pa·s. 2.7 Se 0.3 Thermoelectric material powders are mainly distributed between 4 and 10 μm.

[0084] The number of devices and processing scales described herein are intended to simplify the description of the present invention. Applications, modifications, and variations of the present invention will be readily apparent to those skilled in the art.

[0085] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing bismuth telluride-based thermoelectric material ink for 3D printing, characterized in that: The steps include: Step 1: Pre-dispersing and ball-milling the vacuum-dried bismuth telluride-based thermoelectric material powder. The specific method includes: S1. Add bismuth telluride-based thermoelectric material powder to deionized water, and ultrasonically disperse it at a frequency of 40-80 kHz for 20-40 minutes to obtain a suspension; add 1 mol / L hydrochloric acid to the suspension to adjust the pH of the suspension to 4-5; then add polyethylene glycol-400 to the suspension, ultrasonically disperse it at a frequency of 80-100 kHz for 20-40 minutes, and let it stand for 24-36 hours; filter the stationary suspension, wash it with anhydrous ethanol several times, and dry it to obtain a dispersed powder; the dosage ratio of bismuth telluride-based thermoelectric material powder, polyethylene glycol-400, and deionized water is 2-10 g:0.2-5 mL:250-500 mL, the average relative molecular weight of polyethylene glycol-400 is ≤300 g / mol, and the viscosity is ≤80 mPa·s; S2, the dispersed powder is placed in a ball mill with a ball-to-material ratio of 3:1, ethyl acetate is added to the ball mill as a dispersant, the amount of ethyl acetate is 0.2-1wt% of the dispersed powder, the ball mill speed is 600-800 r / min, the ball milling time is 20-60 min, after ball milling, separation, washing, and drying to obtain pre-dispersed and ball-milled bismuth telluride-based thermoelectric material powder; Step 2: Prepare bismuth telluride-based thermoelectric material powder, solvent, and cross-linking agent according to the component ratio, wherein the solid content of the thermoelectric material powder is 50-80wt%, the mass proportion of the cross-linking agent is 1-5wt%, and the mass proportion of the solvent is 20-50wt%; the cross-linking agent is one or more of polyacrylic acid, polyethyleneimine, polyvinyl pyrrolidone, and methyl cellulose; Step 3: mixing bismuth telluride-based thermoelectric material powder, solvent, and cross-linking agent by mechanical stirring and ball milling to obtain bismuth telluride-based thermoelectric material ink for 3D printing; In the step 1, a thickener is added to the bismuth telluride-based thermoelectric material powder to adjust the rheological properties and fluid behavior, and the mass of the thickener accounts for 0.1-5wt% of the mass of the bismuth telluride-based thermoelectric material powder; The thickener includes one or more of polyvinyl pyrrolidone, methyl cellulose, gelatin, beta-cyclodextrin, hydroxyethyl cellulose, and chitosan.

2. The method for preparing bismuth telluride-based thermoelectric material ink for 3D printing according to claim 1, characterized in that: In the step 2, the mass proportion of the bismuth telluride-based thermoelectric material powder is 50-80 wt %, the mass proportion of the cross-linking agent is 1-5 wt %, and the mass proportion of the solvent is 20-50 wt %.

3. The method for preparing bismuth telluride-based thermoelectric material ink for 3D printing according to claim 1, characterized in that: In the step 1, the bismuth telluride-based thermoelectric material powder is Bi2Te 2.7 Se 0.3 Thermoelectric material powder, wherein the particle size of the bismuth telluride-based thermoelectric material powder is less than 30 μm, wherein the proportion of particles with a size of more than 1 μm cannot be less than 90%, and the proportion of particles with a size of less than 10 μm cannot be less than 50%.

4. The method for preparing bismuth telluride-based thermoelectric material ink for 3D printing according to claim 1, characterized in that: In the step 2, the solvent is one or a mixture of deionized water, ethanol, glycerol, and N,N-dimethylformamide.

5. The method for preparing bismuth telluride-based thermoelectric material ink for 3D printing according to claim 1, characterized in that: In the step three, the specific method of mixing the bismuth telluride-based thermoelectric material powder, the solvent, and the cross-linking agent by mechanical stirring and ball milling includes: mixing the cross-linking agent and the solvent, the mechanical stirring speed is 100~400r / min, and the stirring time is 0.5~2h to obtain a solution; then the obtained solution is mixed with the bismuth telluride-based thermoelectric material powder by ball milling, and the specific parameters are: setting the ball-to-material ratio to 1:1, the clockwise rotation speed is 200~400r / min, and the ball milling is stopped for 5 minutes every 10 minutes; counterclockwise, the rotation speed is 200~400r / min, and the ball milling is stopped for 5 minutes every 10 minutes; the total time is 120~360 minutes.

6. The method for preparing bismuth telluride-based thermoelectric material ink for 3D printing according to claim 1, characterized in that: In the second step, an electrolyte solution is added to the solvent to adjust the pH value of the solvent and control the rheological properties and fluid behavior, and the volume percentage of the electrolyte solution to the solvent is 0.01% to 1%:1; The electrolyte solution includes one or more of ammonia water, sodium hydroxide, sodium bicarbonate, sodium carbonate, sulfuric acid, hydrochloric acid, and nitric acid.

7. An application of a bismuth telluride-based thermoelectric material ink for 3D printing, wherein the bismuth telluride-based thermoelectric material ink is prepared by the method for preparing a bismuth telluride-based thermoelectric material ink for 3D printing according to any one of claims 1 to 6, characterized in that: The bismuth telluride-based thermoelectric material ink is used for 3D printing of thermoelectric devices. The specific application method includes: using an ink direct writing 3D printer to print the bismuth telluride-based thermoelectric material ink according to a preset three-dimensional model to obtain a thermoelectric device, with the gas flow rate set to 0.01-1 mL / min and the platform movement speed set to 1-10 mm / s during printing.

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