Method for preparing thermoelectric film based on ultrahigh temperature reduced graphene oxide film and thermoelectric film
By constructing a temperature field through ultra-high temperature reduction of graphene oxide film and high-temperature thermal shock semiconductor material, the problems of long preparation time and insufficient material performance of existing thermoelectric films have been solved, realizing the rapid preparation and widespread application of flexible films with high Seebeck coefficient.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NAT UNIV OF DEFENSE TECH
- Filing Date
- 2023-03-03
- Publication Date
- 2026-05-19
AI Technical Summary
Existing thermoelectric thin film preparation technologies are time-consuming and complex, and commonly used organic materials have low Seebeck coefficients and poor temperature resistance, making it difficult to meet the needs of flexible thermoelectric materials in aerospace and other fields.
A temperature field was constructed by using ultra-high temperature reduction of graphene oxide film, and thermoelectric films with high Seebeck coefficient and flexibility were prepared by high temperature thermal shock to semiconductor thermoelectric materials. The process was simplified and the processing time was shortened.
It enables the rapid fabrication of high Seebeck coefficient and flexible thermoelectric thin films, suitable for large-scale industrial production. The films can be fabricated on any substrate, have 360° bending performance, and meet the application requirements of aerospace and other fields.
Smart Images
Figure CN116347969B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of thermoelectric thin film technology, and relates to a method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films and thermoelectric thin films. Specifically, it relates to a method for preparing thermoelectric thin films by heating semiconductor metal thermoelectric materials using ultra-high temperature reduced graphene oxide. Background Technology
[0002] Flexible thermoelectric materials have attracted widespread attention in recent years due to their applicability in cutting-edge fields such as aerospace, deep space and deep sea exploration, and energy conversion. Studies have shown that the preparation of lightweight, flexible thermoelectric materials with good thermoelectric properties usually requires the following characteristics: low density, good bending performance, high electrical conductivity, and high Seebeck coefficient.
[0003] Currently, commonly used thermoelectric thin film preparation technologies include vacuum sputtering, electrochemical deposition, and molecular beam epitaxy. Among them, vacuum sputtering can prepare thin films with high purity and quality, but it is time-consuming and easily affected by impurities; electrochemical deposition can easily adjust the composition of the thin film, but the substrate to be deposited must be conductive, and it is also time-consuming; molecular beam epitaxy can precisely control the concentration of thin film components, but it is time-consuming and the preparation conditions are harsh.
[0004] Common thermoelectric thin film materials are mainly organic thermoelectric materials. Although organic thermoelectric materials have excellent flexibility, they have low Seebeck coefficients, poor temperature resistance, and ZT values that are much lower than those of inorganic thermoelectric materials, making it difficult to meet practical needs in many applications. Therefore, developing a flexible thermoelectric thin film with good bending properties, high electrical conductivity, and a high Seebeck coefficient is of great significance. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films that can simplify the process flow, greatly shorten the processing time, and achieve very high efficiency, as well as a thermoelectric thin film with high Seebeck coefficient, high conductivity, and excellent bending performance.
[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.
[0007] A method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films includes the following steps:
[0008] S1. The graphene oxide film is placed in an inert atmosphere and heated to 700℃~900℃ for pre-reduction to obtain a reduced graphene oxide film.
[0009] S2. The reduced graphene oxide film is placed in an inert atmosphere and heated to 2500℃~3000℃ for ultra-high temperature reduction to obtain an ultra-high temperature reduced graphene oxide film.
[0010] S3. Prepare two ultra-high temperature reduced graphene oxide films and one semiconductor thermoelectric material sheet, and prepare a fixture. Place the two ultra-high temperature reduced graphene oxide films in parallel on the fixture to construct a temperature field. Place the semiconductor thermoelectric material sheet in the temperature field to construct a "sandwich" structure and obtain a high temperature thermal shock temperature field fixture.
[0011] S4. The high-temperature thermal shock field device is subjected to high-temperature thermal shock on the semiconductor thermoelectric material sheet under vacuum conditions, with the temperature controlled at 900℃~1100℃, so that the semiconductor thermoelectric material sheet melts, evaporates and is deposited on a substrate to obtain a thermoelectric thin film.
[0012] In the above-described method for preparing thermoelectric films based on ultra-high temperature reduced graphene oxide films, preferably, in step S4, the high-temperature thermal shock time is 10s to 60s, the high-temperature thermal shock is a pulsed high-temperature thermal shock, the vacuum degree is 19Pa to 25Pa, the pulse interval is 1ms to 20ms, the pulse duration is 10ms to 60ms, the output current is 9A to 11A, and the output voltage is 8V to 15V.
[0013] In the above-described method for preparing thermoelectric films based on ultra-high temperature reduction of graphene oxide films, preferably, in step S2, the ultra-high temperature reduction time is 0.5h to 1.5h, and the heating rate is 8℃ / min to 12℃ / min.
[0014] In the above-described method for preparing thermoelectric films based on ultra-high temperature reduction of graphene oxide films, preferably, in step S1, the pre-reduction time is 0.5h to 1.5h, and the heating rate is 3℃ / min to 7℃ / min.
[0015] In the above-described method for preparing thermoelectric films based on ultra-high temperature reduced graphene oxide films, preferably, in step S3, the fixture includes a base plate and two support columns vertically mounted on the base plate. The base plate is provided with adjustment holes for fixing the support columns and adjusting the horizontal distance between the support columns. The tops of the two support columns are provided with clips for fixing the ultra-high temperature reduced graphene oxide films.
[0016] In the above-mentioned method for preparing thermoelectric thin films based on ultra-high temperature reduction graphene oxide thin films, preferably, the base plate is an alumina ceramic base plate, the adjustment holes are four in a cross shape, the support column is an alumina ceramic support column, and the clip is a tungsten metal clip.
[0017] In the above-described method for preparing thermoelectric thin films based on ultra-high temperature reduction of graphene oxide thin films, preferably, in step S3, the semiconductor thermoelectric material press is a p-type bismuth telluride press.
[0018] In the above-described method for preparing thermoelectric films based on ultra-high temperature reduced graphene oxide films, preferably, in step S1, the preparation process of the graphene oxide film is as follows:
[0019] S1.1. The graphene oxide aqueous dispersion stock solution is diluted with water while stirring, and after standing and homogenization, a graphene oxide aqueous dispersion is obtained; wherein, the graphene oxide aqueous dispersion stock solution is a monolayer graphene oxide aqueous dispersion stock solution, the stirring speed is 500 r / min to 1000 r / min, the volume ratio of the graphene oxide aqueous dispersion stock solution to water is 10:3, and the standing time is 1 h to 2 h;
[0020] S1.2. The above-obtained aqueous dispersion of graphene oxide is coated onto a substrate and dried to obtain a graphene oxide film; wherein the coating rate is 1.0 mm / s to 1.4 mm / s, the coating thickness is 1.5 mm to 2 mm, the drying temperature is 35℃ to 40℃, the drying time is 6 h to 12 h, and the substrate is a PET film.
[0021] As a general technical concept, the present invention also provides a thermoelectric thin film prepared by the above-mentioned method for preparing thermoelectric thin films based on ultra-high temperature reduction of graphene oxide thin films.
[0022] Preferably, the thermoelectric thin film has a thickness of 2μm to 4μm, an average Seebeck coefficient of up to 369.54μV / K, and can be bent 360°.
[0023] Compared with the prior art, the advantages of the present invention are as follows:
[0024] (1) The method of this invention constructs a temperature field by reducing graphene oxide film at ultra-high temperature, and places the semiconductor thermoelectric material sheet in the temperature field for high-temperature thermal shock, so that it generates a high thermoelectric potential under the temperature field, and the prepared film has an excellent Seebeck coefficient. At the same time, the high-temperature thermal shock can make the compound thermoelectric material nanoscale, which can further optimize the Seebeck coefficient of the film. The prepared thermoelectric film also has the advantage of flexibility. These two important technical features make the thermoelectric film have the advantages of flexibility, high Seebeck coefficient and thermoelectric potential. The method of this invention realizes the rapid preparation of thermoelectric film, which greatly shortens the processing time and the preparation cycle is short. The effective coating of thermoelectric material can be completed within 60 seconds, which is very efficient. Moreover, the process is simple, convenient and easy to operate, and suitable for large-scale industrial preparation. At present, mature coating methods such as sputtering coating require several hours when the coating thickness is 2 micrometers, and the process parameters are complex.
[0025] (2) The thermoelectric thin film of the present invention can be prepared on any substrate and has advantages such as high flexibility, excellent temperature resistance, and high Seebeck coefficient. The average Seebeck coefficient can reach up to 369.54 μV / K, which meets the performance requirements of thermoelectric materials. It can be widely used in the field of energy conversion and has high application value and good application prospects. The thermoelectric thin film prepared by the method of preparing thermoelectric thin film based on ultra-high temperature reduction graphene oxide film of the present invention has the characteristic of flexibility and can be bent 360°. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the high-temperature thermal shock temperature field tooling in Embodiment 1 of the present invention.
[0027] Figure 2 The above are the EDS energy dispersive spectroscopy results of the thermoelectric thin films prepared in Examples 1-3 and Comparative Example 1 of this invention.
[0028] Figure 3 These are scanning electron microscope (SEM) images of the thermoelectric thin films prepared in Examples 1-3 and Comparative Example 1 of the present invention, wherein (a)-(d) are SEM images of samples Cu-800, Cu-900, Cu-1000, and Cu-1100, respectively.
[0029] Figure 4 The figures show the Seebeck coefficient test results of the thermoelectric thin films prepared in Examples 1-3 and Comparative Example 1 of this invention.
[0030] Legend:
[0031] 1. Base plate; 2. Support column; 3. Adjustment hole; 4. Clip; 5. Ultra-high temperature reduced graphene oxide film; 6. p-type bismuth telluride pellet. Detailed Implementation
[0032] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.
[0033] Example 1
[0034] A method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films according to the present invention specifically involves preparing thermoelectric coatings using ultra-high temperature reduced graphene oxide thermal shock p-type bismuth telluride thermoelectric materials, comprising the following steps:
[0035] (1) Take 20 mL of a single-layer graphene oxide aqueous dispersion stock solution with a concentration of 10 mg / mL (the average radial dimension of the single-layer graphene oxide stock solution is 40 μm-50 μm and the single-layer rate is >95%), place it on a magnetic stirrer and stir rapidly at a stirring rate of 500 r / min. During the stirring process, add 6 mL of deionized water dropwise. After the addition is complete, continue stirring for 30 min. After the stirring is completed, let it stand for 1 h. Then, mix it with a homogenizer to obtain the diluted single-layer graphene oxide aqueous dispersion.
[0036] (2) Pour the diluted monolayer graphene oxide aqueous dispersion obtained in step (1) into the hopper, and use a scraper to uniformly coat the solution onto the PET substrate at a speed of 1.0 mm / s. The coating thickness is 2 mm. Dry at 35°C for 6 h to obtain a graphene oxide film.
[0037] (3) Cut the graphene oxide film obtained in step (2) into 4cm×4cm samples, place them in a tube furnace, heat them to 800℃ at a heating rate of 5℃ / min, hold them at 800℃ for 30min, and then cool them down to room temperature at a cooling rate of 5℃ / min. The entire heat treatment reduction process is carried out in an argon atmosphere to obtain a pre-reduced graphene oxide film at 800℃, denoted as rGO-800.
[0038] (4) The reduced graphene oxide film rGO-800 obtained in step (3) at 800℃ is placed in a graphite furnace and heated to 2500℃ at a heating rate of 10℃ / min. It is then held at 2500℃ for 60min and then cooled to room temperature at a cooling rate of 10℃ / min. The entire heat treatment reduction process is carried out in an argon atmosphere to obtain an ultra-high temperature reduced graphene oxide film reduced at 2500℃, which is denoted as rGO-2500.
[0039] (5) Cut the reduced graphene oxide film rGO-2500 obtained in step (4) at 2500℃ into two small pieces of 9mm×20mm for later use.
[0040] (6) 0.3g of p-type bismuth telluride powder with a particle size of 10μm is pressed into a 9mm×12mm×1mm sheet using a mold. The sheet is pressed under a pressure of 4MPa for 1min to obtain a well-shaped sheet.
[0041] (7) Prepare the fixture. The fixture includes a base plate 1 and two support columns 2 vertically mounted on the base plate 1. The base plate 1 is an alumina ceramic base plate with dimensions of 150mm×150mm×6mm. The base plate 1 has four adjustment holes 3 arranged in a cross shape. The adjustment holes 3 have dimensions of 55mm×10mm×6mm. The adjustment holes 3 are used to fix the support columns 2 and adjust the horizontal distance between the support columns 2. The support columns 2 are alumina ceramic support columns with dimensions of 20mm×20mm×60mm. The top of each of the two support columns 2 is provided with a clip 4 for fixing the ultra-high temperature reduced graphene oxide film. The clip 4 has an opening width of about 9mm and is a tungsten metal clip. Each of the two clips 4 clamps an ultra-high temperature reduced graphene oxide film rGO-2500 and makes them parallel to form a temperature field. The p-type bismuth telluride pellet 6 obtained in step (6) is placed between two rGO-2500 sheets, usually with a distance of less than 1 mm, or they can be directly clamped together to form a "sandwich" structure, thus obtaining a high-temperature thermal shock field tooling, such as... Figure 1 As shown, this structure allows the p-type bismuth telluride film to be heated uniformly.
[0042] (8) The high-temperature thermal shock temperature field fixture obtained in step (7) is assembled into the high-temperature thermal shock test chamber (e.g., a vacuum chamber, which can be connected to a pulse power supply), and a copper foil with a size of 8cm×8cm is fixed on the receiving plate in the chamber. The clamp on the top of the support column is connected to the power supply of the pulse voltage. The chamber is closed, and the atmosphere in the chamber is extracted by a vacuum pump. The vacuum degree is controlled at 23Pa. The pulse interval is controlled at 1ms, the pulse duration is 50ms, the output current is 10A, and the output voltage is 9.1V. The high-temperature thermal shock is performed, and the temperature is controlled at 900℃. The power supply is turned off after 30s. The p-type bismuth telluride pellet melts and evaporates after high-temperature thermal shock, and then a film is deposited on the copper foil substrate to obtain a p-BiSbTe / Cu thermoelectric film (Sb comes from the p-type bismuth telluride pellet). That is, the p-type bismuth telluride copper foil sample prepared by thermal shock of bismuth telluride film material at 900℃ is denoted as Cu-900.
[0043] Example 2
[0044] The present invention provides a method for preparing thermoelectric thin films based on ultra-high temperature reduction of graphene oxide thin films, which is basically the same as the method in Example 1, except that in step (8), the pulse voltage is 10.2V and the temperature is controlled at 1000℃, denoted as Cu-1000.
[0045] Example 3
[0046] The method for preparing thermoelectric thin films based on ultra-high temperature reduction of graphene oxide thin films of the present invention is basically the same as the method in Example 1, except that: in step (8), the pulse voltage is 11.2V and the temperature is controlled at 1100℃, denoted as Cu-1100.
[0047] Comparative Example 1
[0048] The present invention provides a method for preparing thermoelectric thin films based on ultra-high temperature reduction of graphene oxide thin films, which is basically the same as the method in Example 1, except that in step (8), the pulse voltage is 7V and the temperature is controlled at 800℃, denoted as Cu-800.
[0049] Figure 2 The EDS energy dispersive spectroscopy results are shown for the p-BiSbTe / Cu thermoelectric thin films prepared in Comparative Example 1, Examples 1, 2, and 3 of this invention. It can be observed that as the rapid thermal shock temperature increases, the proportion of tellurium (Te) atoms in the p-type bismuth telluride coating continuously decreases, while the proportion of bismuth (Bi) atoms continuously increases.
[0050] Figure 3 The scanning electron microscope images of the p-BiSbTe / Cu thermoelectric thin films prepared in Comparative Example 1, Examples 1, 2, and 3 of this invention show that a dense thin film was formed on the surface of the copper foil substrate, indicating that a complete p-type bismuth telluride coating was successfully prepared on the copper foil surface, with a surface morphology similar to "cauliflower".
[0051] Figure 4 The Seebeck coefficient test results are shown for the p-BiSbTe / Cu thermoelectric thin films prepared in Comparative Example 1, Examples 1, 2, and 3 of this invention. It can be found that the method of this invention has a significant effect on improving the Seebeck coefficient of the coating; the increase in temperature makes the composition of the coating more closely resemble the composition of the raw materials.
[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.
Claims
1. A method for preparing thermoelectric thin films based on ultra-high temperature reduction of graphene oxide thin films, characterized in that, Includes the following steps: S1. The graphene oxide film is placed in an inert atmosphere and heated to 700 ℃~900 ℃ for pre-reduction to obtain a reduced graphene oxide film. S2. The reduced graphene oxide film is placed in an inert atmosphere and heated to 2500 ℃~3000 ℃ for ultra-high temperature reduction to obtain ultra-high temperature reduced graphene oxide film. S3. Prepare two ultra-high temperature reduced graphene oxide films and one semiconductor thermoelectric material sheet, and prepare a fixture. Place the two ultra-high temperature reduced graphene oxide films in parallel on the fixture to construct a temperature field. Place the semiconductor thermoelectric material sheet in the temperature field to construct a "sandwich" structure and obtain a high temperature thermal shock temperature field fixture. S4. The high-temperature thermal shock field device is subjected to high-temperature thermal shock on the semiconductor thermoelectric material sheet under vacuum conditions, with the temperature controlled at 900 ℃~1100 ℃, so that the semiconductor thermoelectric material sheet melts, evaporates and is deposited on a substrate to obtain a thermoelectric thin film.
2. The method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films according to claim 1, characterized in that, In step S4, the high-temperature thermal shock time is 10 s to 60 s, the high-temperature thermal shock is a pulsed high-temperature thermal shock, the vacuum degree is 19 Pa to 25 Pa, the pulse interval is 1 ms to 20 ms, the pulse duration is 10 ms to 60 ms, the output current is 9 A to 11 A, and the output voltage is 8 V to 15 V.
3. The method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films according to claim 1, characterized in that, In step S2, the ultra-high temperature reduction time is 0.5 h to 1.5 h, and the heating rate is 8 ℃ / min to 12 ℃ / min.
4. The method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films according to claim 1, characterized in that, In step S1, the pre-reduction time is 0.5 h to 1.5 h, and the heating rate is 3 ℃ / min to 7 ℃ / min.
5. The method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films according to any one of claims 1 to 4, characterized in that, In step S3, the fixture includes a base plate and two support columns vertically mounted on the base plate. The base plate is provided with adjustment holes for fixing the support columns and adjusting the horizontal distance between the support columns. The top of each of the two support columns is provided with a clamp for fixing the ultra-high temperature reduced graphene oxide film.
6. The method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films according to claim 5, characterized in that, The base plate is an alumina ceramic base plate, there are four adjustment holes arranged in a cross shape, the support column is an alumina ceramic support column, and the clip is a tungsten metal clip.
7. The method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films according to any one of claims 1 to 4, characterized in that, In step S3, the semiconductor thermoelectric material sheet is a p-type bismuth telluride sheet.
8. The method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films according to any one of claims 1 to 4, characterized in that, In step S1, the preparation process of the graphene oxide film is as follows: S1.
1. The graphene oxide aqueous dispersion stock solution is diluted with water while stirring, and after standing and homogenization, an aqueous dispersion of graphene oxide is obtained; wherein, the graphene oxide aqueous dispersion stock solution is a monolayer graphene oxide aqueous dispersion stock solution, the stirring speed is 500 r / min to 1000 r / min, the volume ratio of the graphene oxide aqueous dispersion stock solution to water is 10:3, and the standing time is 1 h to 2 h; S1.
2. The above-obtained aqueous dispersion of graphene oxide is coated onto a substrate and dried to obtain a graphene oxide film; wherein the coating rate is 1.0 mm / s to 1.4 mm / s, the coating thickness is 1.5 mm to 2 mm, the drying temperature is 35 ℃ to 40 ℃, the drying time is 6 h to 12 h, and the substrate is a PET film.
9. A thermoelectric thin film prepared by the method for preparing thermoelectric thin films based on ultra-high temperature reduced graphene oxide thin films as described in any one of claims 1 to 8.
10. The thermoelectric thin film according to claim 9, characterized in that, The thermoelectric film has a thickness of 2μm to 4μm, an average Seebeck coefficient of up to 369.54 μV / K, and can be bent 360°.