A method for the preparation of segmented thermoelectric devices for electronic refrigeration

Abstract

This invention discloses a segmented thermoelectric device for electronic cooling and its fabrication method, comprising an N-type thermoelectric single leg and a P-type thermoelectric single leg. The N-type thermoelectric single leg is formed by a three-step sintering process, and its chemical composition is represented as Ag-Fe / Fe. 90 Sb 10 / Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 / Fe 90 Sb 10 / Bi2Te 2.694 Se 0.3 I 0.006 / Fe 90 Sb 10 / Ag-Fe; P-type thermoelectric single leg is sintered in one step, and its chemical composition is represented as Ag-Fe / Fe. 90 Sb 10 / Bi 0.07 Ge 0.9 Te / Fe 90 Sb 10 / Ag-Fe. The results show that Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 and Bi2Te 2.694 Se 0.3 I 0.006 Two types of N-type thermoelectric materials and P-type thermoelectric material Bi 0.07 Ge 0.9 Te has good matching properties in thermoelectric performance. Through the synergistic effect of the two, the open-circuit voltage, current and output power of the final segmented thermoelectric device can be greatly improved, thereby meeting the strict requirements of precision temperature control in actual scenarios.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric cooling device technology, and specifically relates to a method for preparing a segmented thermoelectric device for electronic cooling. Background Technology

[0002] Thermoelectric cooling devices achieve highly efficient energy conversion thanks to the unique properties of thermoelectric materials. Operating based on the Peltier effect, they eliminate the need for traditional refrigerants, making them environmentally friendly and noiseless. With no moving parts, they significantly reduce the probability of mechanical failures and lower maintenance costs. They have high application value in fields with extremely high temperature control requirements, such as cold chain, electronics, and medical fields, effectively solving complex temperature control problems. For example, in the cold chain industry, they precisely maintain low-temperature environments to ensure the freshness and quality of food and medicine; in the electronics field, they provide stable heat dissipation for precision electronic equipment, extending its lifespan; and in the medical field, they meet the stringent temperature requirements of medical equipment, providing reliable support for medical diagnosis and treatment. With the continuous growth of global energy demand and increasingly stringent requirements for temperature control and energy efficiency, the research, innovation, and promotion of thermoelectric cooling devices are becoming increasingly important. Increased R&D investment not only promotes innovative development in the energy and related industries but also plays a significant role in achieving sustainable energy development, promoting energy conservation and emission reduction, and actively addressing environmental challenges.

[0003] Thermoelectric cooling devices operate based on the Peltier effect, whereby when current flows through a closed loop formed by two different conductors or semiconductors, heat absorption or release occurs at the two connection points, thus transferring heat and achieving cooling or heating. These devices typically consist of multiple P-type and N-type semiconductor elements connected in thermal parallel and electrical series. During cooling operation, a DC power supply is applied, and current flows through the device. Electrons undergo energy conversion at the junctions of the different materials. One connection point absorbs heat, achieving localized cooling; the other connection point releases heat, transferring the absorbed heat away. Device performance is influenced by various factors, including the thermoelectric properties of the materials (such as Seebeck coefficient, electrical conductivity, and thermal conductivity) and the device structure (including shape, size, connection method, and interface materials). Common thermoelectric materials include bismuth-antimony alloys, silicon-germanium alloys, and tellurium-bismuth alloys. A well-designed structure can improve cooling efficiency.

[0004] Thermoelectric cooling materials encompass various types, among which bismuth telluride and its alloys are among the most widely used materials in the field of thermoelectric cooling. Their optimal operating temperature is below 450K, exhibiting superior thermoelectric properties in the low-temperature range, enabling efficient conversion of heat and electrical energy to achieve a cooling effect. As a result, it frequently appears in many everyday and professional scenarios, such as small freezers, precisely maintaining a low-temperature environment to ensure proper storage; thermostats, constantly controlling temperature stability; and in the cooling systems of electronic devices, effectively dissipating heat to ensure normal equipment operation. It also plays a crucial role in professional fields such as medicine, nuclear physics, and vacuum technology.

[0005] The energy conversion efficiency of thermoelectric devices is usually an important indicator for evaluating their performance. This is achieved by testing the open-circuit voltage, open-circuit current, and output power of the thermoelectric device, and then combining this with the efficiency formula. Q c It refers to cooling capacity, P. out It is the output power, from which the conversion efficiency of the thermoelectric device can be calculated.

[0006] The primary consideration in selecting Bi2Te3 and Mg3Sb2 as thermoelectric refrigeration materials is their excellent thermoelectric properties. The quality of thermoelectric materials is often measured by their thermoelectric figure of merit, T = S. 2 Using σT / κ as a scale, both exhibit high ZT values ​​within a specific temperature range. Bi2Te3, as a classic thermoelectric material, exhibits a Seebeck coefficient and electrical conductivity in balance across the low to medium temperature range, resulting in high electron carrier concentration and fast thermoelectric energy conversion efficiency. Meanwhile, the emerging Mg3Sb2 is compatible with Bi2Te3 in a similar operating temperature range and can be used as a segmented single-leg material.

[0007] Bi2Te3 is suitable for operation at room temperature and below, especially for applications such as electronic device cooling and small refrigeration equipment. Mg3Sb2 can also be used for low-temperature devices through doping and other processes. Both materials are compatible with metal electrodes and buffer materials when fabricating thermoelectric devices, and are suitable for welding and interface treatment, ensuring undamaged performance after being assembled into a high-efficiency thermoelectric circuit. In terms of process maturity, Bi2Te3 has methods such as melt growth, mechanical alloying, and chemical vapor deposition, making its microstructure easily controllable; Mg3Sb2's solid-state reaction method is also more conducive to mass production. Furthermore, the reserves of raw materials such as bismuth, tellurium, magnesium, and antimony are not scarce, reducing the cost of thermoelectric devices. Summary of the Invention

[0008] Therefore, the purpose of this invention is to provide a segmented thermoelectric device for electronic cooling and a method for its fabrication.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A first aspect of the present invention provides a segmented thermoelectric device for electronic cooling, the segmented thermoelectric device comprising an N-type thermoelectric leg and a P-type thermoelectric leg, wherein the N-type thermoelectric leg has a chemical composition represented as Ag-Fe / Fe. 90 Sb 10 / Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 / Fe 90 Sb 10 / Bi2Te 2.694 Se 0.3 I 0.006 / Fe 90 Sb 10 / Ag-Fe, this N-type thermoelectric single leg is composed of a first N-type thermoelectric material, a second N-type thermoelectric material, and a buffer layer and a weldable connection layer respectively laminated on both sides and in the middle of the first N-type thermoelectric material and the second N-type thermoelectric material, wherein Fe 90 Sb 10 As a buffer layer, Ag-Fe forms a weldable bonding layer, and Mg... 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 Bi2Te is the first type N thermoelectric material. 2.694 Se 0.3 I 0.006 It is a second type N thermoelectric material.

[0011] The P-type thermoelectric single leg has the chemical composition represented as Ag-Fe / Fe. 90 Sb 10 / Bi 0.07 Ge 0.9 Te / Fe 90 Sb 10 / Ag-Fe, this P-type thermoelectric single leg consists of a P-type thermoelectric material, a buffer layer sequentially laminated to both sides of the P-type thermoelectric material, and a weldable connecting layer; wherein, Fe 90 Sb 10 As a buffer layer, Ag-Fe is a weldable bonding layer, and Bi... 0.07 Ge 0.9 Te is a P-type thermoelectric material.

[0012] Preferably, in the N-type thermoelectric single leg, the thickness of the first N-type thermoelectric material is 2-4 mm, the thickness of the second N-type thermoelectric material is 0.5-1 mm, the thickness of the buffer layer is 0.1-0.3 mm, and the thickness of the weldable connection layer is 0.4-0.8 mm.

[0013] Preferably, in the P-type thermoelectric single leg, the thickness of the P-type thermoelectric material is 2-4 mm, the thickness of the buffer layer is 0.1-0.3 mm, and the thickness of the weldable connection layer is 0.4-0.8 mm.

[0014] Preferably, the dimensions of the N-type thermoelectric single leg are (1-3) mm × (1-3) mm × (3-5) mm.

[0015] Preferably, the dimensions of the P-type thermoelectric single leg are (1-3) mm × (1-3) mm × (3-5) mm.

[0016] Preferably, the segmented thermoelectric device further includes a copper electrode and an alumina ceramic substrate, wherein the copper electrode and the alumina ceramic substrate are bonded together by a copper plating (DBC) process, the thickness of the copper electrode is 0.1-0.3 mm, the thickness of the alumina ceramic substrate is 0.6-0.8 mm, and the dimensions are 5-5.5 mm × 5-5.5 mm.

[0017] A second aspect of the present invention provides a method for fabricating the above-described segmented thermoelectric device for electronic cooling, comprising the following steps:

[0018] S1. Preparation of N-type thermoelectric single leg:

[0019] S11, Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 The powder is loaded into a graphite mold and compacted, and then hot-pressed and sintered to obtain a block.

[0020] S12, Bi2Te 2.694 Se 0.3 I 0.006 The powder was loaded into a graphite mold and compacted, and then hot-pressed and sintered to obtain block two;

[0021] S13, Ag-Fe powder, Fe 90 Sb 10 The powder, block one, and block two are layered and packed into the graphite mold in the order of the N-type thermoelectric single leg composition and compacted.

[0022] S14. Place the loaded graphite mold in a vacuum hot pressing device for hot pressing and sintering to obtain a block sample.

[0023] S15, Cutting and Shaping: Cut the block sample to obtain an N-type thermoelectric single leg of the target size;

[0024] S2. Preparation of P-type thermoelectric single leg:

[0025] S21, Ag-Fe powder, Bi0.07 Ge 0.9 Te powder, Fe 90 Sb 10 The powder was loaded into the graphite mold and compacted according to the P-type thermoelectric single-leg composition structure.

[0026] S22. Place the loaded graphite mold in a spark plasma sintering equipment and perform spark plasma sintering to obtain a cylindrical sample.

[0027] S23. Cut the cylindrical sample to obtain a P-type thermoelectric single leg of the target size;

[0028] S3, gold plating, soldering, and assembly:

[0029] The obtained N-type and P-type thermoelectric single legs are gold-plated and soldered, and then assembled with copper electrodes and alumina ceramic substrates to obtain segmented thermoelectric devices.

[0030] Preferably, in step S11, the hot pressing sintering temperature is 700–780 K, the sintering pressure is 750–800 Kg, and the sintering time is 15–35 min. Since hot pressing sintering equipment typically uses kilograms (Kg) as the pressure display unit, kilograms (Kg) are used as the pressure measurement unit in this invention.

[0031] Preferably, in step S12, the hot pressing sintering temperature is 500-580K, the sintering pressure is 600-680Kg, and the sintering time is 15-35min.

[0032] Preferably, in step S14, the hot pressing sintering temperature is 400-550K, the sintering pressure is 400-480Kg, and the sintering time is 60-70min.

[0033] Preferably, in step S22, the discharge plasma sintering temperature is 700–780 K and the sintering time is 6–15 min.

[0034] Preferably, the cutting and forming process conditions are as follows: the sample is cut using an electrical discharge wire with a wire diameter of 0.35 to 0.45 mm.

[0035] Preferably, after the cutting and shaping, it is necessary to clean it. The cleaning conditions are: ultrasonic cleaning with ethanol for 20 to 30 minutes.

[0036] Preferably, in step S3, the gold plating process is carried out using a micro ion sputtering instrument with cold plating technology; the welding process uses tin-lead solder and the welding time is 20-25 seconds.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) This invention clarifies the differences in cooling capacity among different materials through simulation. Simultaneously, it strictly adheres to the thermoelectric figure of merit (zT) selection principle and further evaluates the thermoelectric conversion efficiency of the materials to screen out the high-performance P-type thermoelectric material Bi. 0.07 Ge 0.9 Te exhibits unique advantages and potential in thermoelectric properties. Based on the scientific screening principle of tolerance factor S, Mg was further selected. 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 and Bi2Te 2.694 Se 0.3 I 0.006 These two N-type thermoelectric materials form an N-type segmented single leg. Fe is selected. 90 Sb 10 The buffer layer is Ag-Fe, which is a weldable bonding layer. The barrier layer is Fe. 90 Sb 10 It possesses unique properties, specifically: First, its coefficient of thermal expansion (CTE) is not significantly different from that of the selected first-type N-type thermoelectric materials and second-type N-type thermoelectric materials; at a temperature of 373K, its CTE value is 15.3 × 10⁻⁶. -6 K -1 Secondly, the Fe barrier layer 90 Sb 10 The thermal diffusion is small. In N-type monolithic layered materials, the middle barrier layer can connect the first N-type thermoelectric material and the second N-type thermoelectric material, and can also increase the stability of the N-type monolithic layered material, while effectively preventing the thermal diffusion of the "Sb" element in the first and second N-type thermoelectric materials. The barrier layers on both sides, in addition to having the same functions as the middle barrier layer, can also prevent the thermal diffusion of the "Fe" element in the solderable layer. The solderable layer has a number of unique and important properties and functions. In terms of properties, firstly, the coefficient of thermal expansion (CTE) of the solderable layer is not much different from that of the selected first and second N-type thermoelectric materials. At 373K, its CTE value is 18.3 × 10⁻⁶. -6 K -1 Secondly, the electrical conductivity of the solderable layer is very high, reaching 3.17 × 10⁻⁶. 7 cm -3 Thirdly, the "Ag" in the solderable layer can form an intermetallic compound AgSn with the "Sn" in the solder, and the CTE of this compound is 19.3 × 10⁻⁶. -6 K -1Fourth, the Fe in the solderable layer does not react with the solder and exists in elemental form at the joint. Functionally, the solderable layer enhances the stability of the weld, allowing the thermoelectric material to be stably welded to the copper electrode.

[0039] The research results indicate that the above-mentioned Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 and Bi2Te 2.694 Se 0.3 I 0.006 Two types of N-type thermoelectric materials and P-type Bi 0.07 Ge 0.9 Te materials exhibit excellent thermoelectric properties, and through their synergistic effect, the open-circuit voltage, current, and output power of the resulting thermoelectric devices are significantly improved. This enables them to meet the stringent requirements of high-precision, stable, and reliable device cooling and precise temperature control technologies in practical applications. It provides a superior cooling solution for high-precision semiconductor lasers, quantum computing, and other precision low-temperature applications, thereby enhancing their practicality and market competitiveness in various scenarios and demonstrating significant industrial value and innovative significance.

[0040] (2) Existing thermoelectric devices suffer from significant differences in the sintering temperatures of different N-type materials, making it difficult to successfully sinter these materials together. This directly limits the achievement of high open-circuit voltage, high current, and high output power in thermoelectric cooling devices. To address this challenge, this invention innovates at the design level, abandoning the traditional commercial N-type single thermoelectric material Bi2Te. 2.694 Se 0.3 I 0.006 The invention designs the thermoelectric material into segmented first and second N-type thermoelectric materials and connects them using a barrier layer, effectively improving the open-circuit voltage, current, and output power of the thermoelectric cooling device. In terms of manufacturing process, this invention employs a three-step method to prepare the N-type thermoelectric single leg, overcoming the technical challenge of fabrication failure caused by excessively large differences in sintering temperatures between different materials in existing segmented thermoelectric single legs.

[0041] (3) The preparation method of this invention has many outstanding advantages, specifically as follows: This invention improves the open-circuit voltage, current, and output power of thermoelectric cooling devices by changing the traditional commercial N-type single thermoelectric material to a segmented design and using a barrier layer for connection. This innovative technology provides new ideas and directions for industry development. In terms of process operation, this invention uses a three-step method to prepare N-type thermoelectric single legs, which is simple, easy to operate, and easy to master, effectively simplifying the manufacturing process and greatly improving production efficiency. Moreover, the method of this invention effectively solves the technical problem of manufacturing failure caused by excessive differences in sintering temperatures of different materials. It has good compatibility with various materials and can adapt to the sintering requirements of different types of N-type materials, demonstrating strong adaptability. At the same time, because the method of this invention has clear steps, stable parameters, and high repeatability, it can ensure the consistency of product quality, and is therefore suitable for large-scale industrial production. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A schematic flowchart illustrating a method for fabricating a segmented thermoelectric device for electronic refrigeration provided by the present invention.

[0044] Figure 2 This is a schematic diagram of the N-type thermoelectric single leg and P-type thermoelectric single leg of the segmented structure in the segmented thermoelectric device prepared in Example 1.

[0045] Figure 3 This is a schematic diagram of the N-type thermoelectric single leg and the P-type thermoelectric single leg in the thermoelectric device prepared in Comparative Example 1.

[0046] Figure 4 The performance measurement results of the segmented thermoelectric device prepared in Example 1 are as follows: (a) open-circuit voltage; (b) resistance; (c) open-circuit current; (d) output power.

[0047] Figure 5 The performance measurement results of the segmented thermoelectric device obtained in Example 2 are as follows: (a) open-circuit voltage; (b) resistance; (c) open-circuit current; (d) output power.

[0048] Figure 6 The performance measurement results of the segmented thermoelectric device prepared in Example 3 are as follows: (a) open-circuit voltage; (b) resistance; (c) open-circuit current; (d) output power.

[0049] Figure 7 The performance measurement results of the thermoelectric device prepared in Comparative Example 1 are as follows: (a) open-circuit voltage; (b) resistance; (c) open-circuit current; (d) output power. Detailed Implementation

[0050] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention may be implemented in other embodiments without these specific details.

[0051] Example 1

[0052] See Figure 1 A method for fabricating a segmented thermoelectric device for electronic refrigeration, the segmented thermoelectric device comprising a P-type thermoelectric single leg and an N-type thermoelectric single leg, comprising the following steps:

[0053] I. Material preparation for thermoelectric single leg:

[0054] 1. Preparation of N-type thermoelectric single-leg material;

[0055] (1) Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 The powder was uniformly compacted into a graphite abrasive mold with a diameter of 10.0 mm, wherein Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 The thermoelectric material has a height of 2.4 mm, and is then hot-pressed and sintered under a pressure of 775 kg to achieve a sintering temperature of 750 K and a holding time of 20 min to obtain block one.

[0056] (2) Bi2Te 2.694 Se 0.3 I 0.006 The powder was uniformly compacted into a graphite abrasive mold with a diameter of 10.0 mm, wherein Bi2Te 2.694 Se 0.3 I 0.006 The thermoelectric material has a height of 0.6 mm, and is then hot-pressed and sintered under a pressure of 643 kg at a sintering temperature of 550 K for 20 min to obtain block two.

[0057] (3) The obtained block one, block two, and Fe as a buffer layer 90 Sb 10 And the Ag-Fe as the welding layer is segmented in the order of Ag-Fe / Fe. 90 Sb10 / Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 / Fe 90 Sb 10 / Bi2Te 2.694 Se 0.3 I 0.006 / Fe 90 Sb 10 / Ag-Fe was compacted into a graphite mold with a diameter of 10.0 mm, and then hot-pressed and sintered under a pressure of 450 kg, at a sintering temperature of 500 K and a holding time of 65 min to obtain a block sample.

[0058] 2. Preparation of P-type thermoelectric single-leg material:

[0059] Bi 0.07 Ge 0.9 Te powder, Fe as a buffer layer 90 Sb 10 And Ag-F, which serves as a weldable bonding layer, is segmented in the order of Ag-Fe / Fe. 90 Sb 10 / Bi 0.07 Ge 0.9 Te / Fe 90 Sb 10 / Ag-Fe was compacted into a graphite mold with a diameter of 10.0 mm, and then the resulting powder was subjected to spark plasma (densification) sintering under a pressure of 775 kg. The sintering temperature was 750 K and the holding time was 8 mins to obtain a cylindrical sample.

[0060] II. Cutting thermoelectric materials:

[0061] (1) The above-obtained block sample was cut into cuboid blocks with dimensions of 1.6mm × 1.6mm × 3.0mm by wire electrical discharge machining, and then ultrasonically cleaned with ethanol for 20 minutes to obtain an N-type thermoelectric single leg (see...). Figure 2 );

[0062] (2) The cylindrical sample obtained above was cut into cuboid blocks with dimensions of 1.6 × 1.6 × 3.0 mm by wire electrical discharge machining. Then, it was ultrasonically cleaned with ethanol for 20 min to obtain a highly dense cylindrical sample (diameter 10.0 mm × height 3.0 mm), i.e., a P-type thermoelectric single leg (see...). Figure 2 );

[0063] III. Gold plating and soldering:

[0064] The obtained N-type thermoelectric single leg and P-type thermoelectric single leg were gold-plated using a micro ion sputtering instrument and cold plating technology, and then soldered using tin-lead solder.

[0065] IV. Assembly and Independent Testing:

[0066] A 0.2 mm thick copper electrode and a 0.635 mm thick alumina ceramic substrate are bonded together using the direct copper cladding (DBC) process and then assembled to obtain a segmented thermoelectric device with a 2×2 structure.

[0067] In the laboratory, a platform was built to conduct independent performance tests on the obtained segmented thermoelectric devices. The temperature of the cold end of the N-type thermoelectric device was set at 18.4℃, and the temperature of the hot end of the P-type thermoelectric device was set at 33.4℃, with a temperature difference of 15K. A 60-second test was conducted, and the results are shown below. Figure 4 .

[0068] Depend on Figure 4 (a)- Figure 4 (d) The results show that the highest open-circuit voltage of the segmented thermoelectric device prepared in this embodiment is 19.9261mV, the average internal resistance is 0.670165Ω, the highest open-circuit current is 2.40393A, and the highest output power is 18.30924mW.

[0069] Example 2

[0070] A method for fabricating a segmented thermoelectric device for electronic cooling, the segmented thermoelectric device comprising a P-type thermoelectric leg and an N-type thermoelectric leg, comprising the following steps:

[0071] I. Material preparation for thermoelectric single leg:

[0072] 1. Preparation of N-type thermoelectric single-leg material;

[0073] (1) Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 The powder was uniformly compacted into a graphite abrasive mold with a diameter of 10.0 mm, wherein Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 The thermoelectric material has a height of 2.4 mm, and is then hot-pressed and sintered under a pressure of 750 kg to achieve a sintering temperature of 700 K and a holding time of 15 min to obtain block one.

[0074] (2) Bi2Te 2.694 Se 0.3 I 0.006The powder was uniformly compacted into a graphite abrasive mold with a diameter of 10.0 mm, wherein Bi2Te 2.694 Se 0.3 I 0.006 The thermoelectric material has a height of 0.6 mm, and is then hot-pressed and sintered under a pressure of 600 kg at a sintering temperature of 500 K for 15 min to obtain block two.

[0075] (3) The obtained block one, block two, and Fe as a buffer layer 90 Sb 10 And the Ag-Fe as the welding layer is segmented in the order of Ag-Fe / Fe. 90 Sb 10 / Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 / Fe 90 Sb 10 / Bi2Te 2.694 Se 0.3 I 0.006 / Fe 90 Sb 10 / Ag-Fe was compacted into a graphite mold with a diameter of 10.0 mm, and then hot-pressed and sintered under a pressure of 400 kg, at a sintering temperature of 400 K and a holding time of 60 min to obtain a bulk sample.

[0076] 2. Preparation of P-type thermoelectric single-leg material:

[0077] Bi 0.07 Ge 0.9 Te powder, Fe as a buffer layer 90 Sb 10 And Ag-F, which serves as a weldable bonding layer, is segmented in the order of Ag-Fe / Fe. 90 Sb 10 / Bi 0.07 Ge 0.9 Te / Fe 90 Sb 10 / Ag-Fe was compacted into a graphite mold with a diameter of 10.0 mm, and then the resulting powder was subjected to spark plasma (densification) sintering under a pressure of 775 kg. The sintering temperature was 750 K and the holding time was 8 mins to obtain a cylindrical sample.

[0078] II. Cutting thermoelectric materials:

[0079] (1) The above-obtained block sample was cut into a cuboid block with a size of 1.6mm×1.6mm×3.0mm by wire electrical discharge machining, and then ultrasonically cleaned with ethanol for 20 minutes to obtain an N-type thermoelectric single leg.

[0080] (2) The cylindrical sample obtained above was cut into a cuboid block with a size of 1.6×1.6×3.0mm by wire electrical discharge machining. Then it was ultrasonically cleaned with ethanol for 20min to obtain a highly dense cylindrical sample (diameter 10.0mm×height 3.0mm), i.e. P-type thermoelectric single leg.

[0081] III. Gold plating and soldering:

[0082] The obtained N-type thermoelectric single leg and P-type thermoelectric single leg were gold-plated using a micro ion sputtering instrument and cold plating technology, and then soldered using tin-lead solder.

[0083] IV. Assembly and Independent Testing:

[0084] A 0.2 mm thick copper electrode and a 0.635 mm thick alumina ceramic substrate are bonded together using the direct copper cladding (DBC) process and then assembled to obtain a segmented thermoelectric device with a 2×2 structure.

[0085] In the laboratory, a platform was built to conduct independent performance tests on the obtained segmented thermoelectric devices. The temperature of the cold end of the N-type thermoelectric device was set at 18.4℃, and the temperature of the hot end of the P-type thermoelectric device was set at 33.4℃, with a temperature difference of 15K. A 60-second test was conducted, and the results are shown below. Figure 5 .

[0086] Depend on Figure 5 (a)- Figure 5 (d) The results show that the highest open-circuit voltage of the segmented thermoelectric device prepared in this embodiment is 10.40892mV, the average internal resistance is 0.670163Ω, the highest open-circuit current is 1.66571A, and the highest output power is 10.92737mW.

[0087] Example 3

[0088] A method for fabricating a segmented thermoelectric device for electronic cooling, the segmented thermoelectric device comprising a P-type thermoelectric leg and an N-type thermoelectric leg, comprising the following steps:

[0089] I. Material preparation for thermoelectric single leg:

[0090] 1. Preparation of N-type thermoelectric single-leg material;

[0091] (1) Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01The powder was uniformly compacted into a graphite abrasive mold with a diameter of 10.0 mm, wherein Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 The thermoelectric material has a height of 2.4 mm, and is then hot-pressed and sintered under a pressure of 800 kg to achieve a sintering temperature of 780 K and a holding time of 35 min to obtain block one.

[0092] (2) Bi2Te 2.694 Se 0.3 I 0.006 The powder was uniformly compacted into a graphite abrasive mold with a diameter of 10.0 mm, wherein Bi2Te 2.694 Se 0.3 I 0.006 The thermoelectric material has a height of 0.6 mm, and is then hot-pressed and sintered under a pressure of 680 kg at a sintering temperature of 580 K for 35 min to obtain block two.

[0093] (3) The obtained block one, block two, and Fe as a buffer layer 90 Sb 10 And the Ag-Fe as the welding layer is segmented in the order of Ag-Fe / Fe. 90 Sb 10 / Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 / Fe 90 Sb 10 / Bi2Te 2.694 Se 0.3 I 0.006 / Fe 90 Sb 10 / Ag-Fe was compacted into a graphite mold with a diameter of 10.0 mm, and then hot-pressed and sintered under a pressure of 480 kg at a sintering temperature of 550 K for 70 min to obtain a bulk sample.

[0094] 2. Preparation of P-type thermoelectric single-leg material:

[0095] Bi 0.07 Ge 0.9 Te powder, Fe as a buffer layer 90 Sb 10 And Ag-F, which serves as a weldable bonding layer, is segmented in the order of Ag-Fe / Fe. 90 Sb 10 / Bi 0.07 Ge 0.9 Te / Fe90 Sb 10 / Ag-Fe was compacted into a graphite mold with a diameter of 10.0 mm, and then the resulting powder was subjected to spark plasma (densification) sintering under a pressure of 775 kg. The sintering temperature was 750 K and the holding time was 8 mins to obtain a cylindrical sample.

[0096] II. Cutting thermoelectric materials:

[0097] (1) The above-obtained block sample was cut into a cuboid block with a size of 1.6mm×1.6mm×3.0mm by wire electrical discharge machining, and then ultrasonically cleaned with ethanol for 20 minutes to obtain an N-type thermoelectric single leg.

[0098] (2) The cylindrical sample obtained above was cut into a cuboid block with a size of 1.6×1.6×3.0mm by wire electrical discharge machining. Then it was ultrasonically cleaned with ethanol for 20min to obtain a highly dense cylindrical sample (diameter 10.0mm×height 3.0mm), i.e. P-type thermoelectric single leg.

[0099] III. Gold plating and soldering:

[0100] The obtained N-type thermoelectric single leg and P-type thermoelectric single leg were gold-plated using a micro ion sputtering instrument and cold plating technology, and then soldered using tin-lead solder.

[0101] IV. Assembly and Independent Testing:

[0102] A 0.2 mm thick copper electrode and a 0.635 mm thick alumina ceramic substrate are bonded together using the direct copper cladding (DBC) process and then assembled to obtain a segmented thermoelectric device with a 2×2 structure.

[0103] In the laboratory, a platform was built to conduct independent performance tests on the obtained segmented thermoelectric devices. The temperature of the cold end of the N-type thermoelectric device was set at 18.4℃, and the temperature of the hot end of the P-type thermoelectric device was set at 33.4℃, with a temperature difference of 15K. A 60-second test was conducted, and the results are shown below. Figure 6 .

[0104] Depend on Figure 6 (a)- Figure 6 (d) The results show that the highest open-circuit voltage of the segmented thermoelectric device prepared in this embodiment is 9.8814mV, the average internal resistance is 0.670164Ω, the highest open-circuit current is 1.84439A, and the highest output power is 11.50606mW.

[0105] Comparative Example 1

[0106] A method for fabricating a thermoelectric device based on a single unlayered N-type material includes the following steps:

[0107] I. Material preparation for thermoelectric single leg:

[0108] 1. Preparation of N-type thermoelectric single-leg material;

[0109] (1) Bi2Te 2.694 Se 0.3 I 0.006 Powder, Fe as a buffer layer 90 Sb 10 And the Ag-Fe as the welding layer, in the unsegmented order, is Ag-Fe / Fe. 90 Sb 10 Bi2Te 2.694 Se 0.3 I 0.006 / Fe 90 Sb 10 / Ag-Fe was compacted into a graphite mold with a diameter of 10.0 mm, and then hot-pressed and sintered under a pressure of 643 kg at a sintering temperature of 550 K for 20 min to obtain a bulk sample.

[0110] 2. Preparation of P-type thermoelectric single-leg material:

[0111] Bi 0.07 Ge 0.9 Te powder, Fe as a buffer layer 90 Sb 10 And Ag-F, which serves as a weldable bonding layer, is segmented in the order of Ag-Fe / Fe. 90 Sb 10 / Bi 0.07 Ge 0.9 Te / Fe 90 Sb 10 / Ag-Fe was compacted into a graphite mold with a diameter of 10.0 mm, and then the resulting powder was subjected to spark plasma (densification) sintering under a pressure of 775 kg. The sintering temperature was 750 K and the holding time was 8 mins to obtain a cylindrical sample.

[0112] II. Cutting thermoelectric materials:

[0113] (1) The above-obtained block sample was cut into cuboid blocks with dimensions of 1.6mm × 1.6mm × 3.0mm by wire electrical discharge machining, and then ultrasonically cleaned with ethanol for 20 minutes to obtain an N-type thermoelectric single leg (see...). Figure 3 );

[0114] (2) The cylindrical sample obtained above was cut into cuboid blocks with dimensions of 1.6 × 1.6 × 3.0 mm by wire electrical discharge machining. Then, it was ultrasonically cleaned with ethanol for 20 min to obtain a highly dense cylindrical sample (diameter 10.0 mm × height 3.0 mm), i.e., a P-type thermoelectric single leg (see...). Figure 3 ):

[0115] III. Gold plating and soldering:

[0116] The obtained N-type thermoelectric single leg and P-type thermoelectric single leg were gold-plated using a micro ion sputtering instrument and cold plating technology, and then soldered using tin-lead solder.

[0117] IV. Assembly and Independent Testing:

[0118] A 0.2 mm thick copper electrode and a 0.635 mm thick alumina ceramic substrate are bonded together using the direct copper cladding (DBC) process and then assembled to obtain a segmented thermoelectric device with a 2×2 structure.

[0119] In the laboratory, a platform was built to conduct independent performance tests on the obtained segmented thermoelectric devices. The temperature of the cold end of the N-type thermoelectric device was set at 18.4℃, and the temperature of the hot end of the P-type thermoelectric device was set at 33.4℃, with a temperature difference of 15K. A 60-second test was conducted, and the results are shown below. Figure 7 .

[0120] Depend on Figure 7 (a)- Figure 7 (d) The results show that the thermoelectric device prepared in this comparative example has a maximum open-circuit voltage of 7.529567mV, an average internal resistance of 0.70751Ω, a maximum open-circuit current of 0.90934A, and a maximum output power of 6.15369mW.

[0121] The performance results of the thermoelectric devices prepared in Examples 1-3 and Comparative Example 1 are compared, and the specific results are shown in Table 1.

[0122] Table 1.

[0123] Implementation Name Maximum open-circuit voltage (mV) Average internal resistance (Q) Maximum open-circuit current (mA) Maximum output power (mW) Comparative Example 1 7.529567 0.70751 0.90934 6.15369 Example 1 19.9261 0.670165 2.40393 18.30924 Example 2 10.40892 0.670163 1.66571 10.92737 Example 3 9.88154 0.670164 1.84439 11.50606

[0124] As shown in Table 1, the highest open-circuit voltage, open-circuit current, and output power of the segmented thermoelectric devices prepared in Examples 1-3 of this invention are all higher than those of Comparative Example 1, while the average internal resistance is lower. This indicates that the thermoelectric devices based on layered N-type materials (two types of N-type materials) prepared in Examples 1-3 of this invention exhibit significantly improved performance compared to the thermoelectric device based on a single, unlayered N-type material prepared in Comparative Example 1.

[0125] Comparing the results of Example 1 and Examples 2-3, it can be seen that the highest open-circuit voltage, open-circuit current, and output power of the segmented thermoelectric devices prepared in Examples 2-3 are all lower than those in Comparative Example 1. This is because the sintering temperature and pressure are significantly reduced or increased. It can be seen that if the sintering temperature and pressure are too low or too high, it will lead to failure to sinter densely, resulting in increased resistance and irreversible consequences such as non-conductivity. In addition, the thermoelectric single leg prepared under this condition will face mechanical deformation, including irreversible reactions such as cracks and twisting, resulting in the inability to assemble it into a thermoelectric device.

[0126] This invention is not limited to the specific embodiments described above. Any modifications made by those skilled in the art based on the above concept without creative effort are within the scope of protection of this invention.

Claims

1. A segmented thermoelectric device for electronic cooling, comprising an N-type thermoelectric leg and a P-type thermoelectric leg, characterized in that, The N-type thermoelectric single leg has the chemical composition represented as Ag-Fe / Fe. 90 Sb 10 / Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 / Fe 90 Sb 10 / Bi2Te 2.694 Se 0.3 I 0.006 / Fe 90 Sb 10 / Ag-Fe, the N-type thermoelectric single leg is composed of a first N-type thermoelectric material, a second N-type thermoelectric material, and a buffer layer and a weldable connection layer respectively laminated on both sides and in the middle of the first N-type thermoelectric material and the second N-type thermoelectric material, wherein Fe 90 Sb 10 As a buffer layer, Ag-Fe forms a weldable bonding layer, and Mg... 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 Bi2Te is the first type N thermoelectric material. 2.694 Se 0.3 I 0.006 It is a second type N thermoelectric material; The P-type thermoelectric single leg has the chemical composition represented as Ag-Fe / Fe. 90 Sb 10 / Bi 0.07 Ge 0.9 Te / Fe 90 Sb 10 / Ag-Fe, the P-type thermoelectric single leg is composed of a P-type thermoelectric material, a buffer layer and a weldable connection layer respectively laminated on both sides of the P-type thermoelectric material; wherein, Fe 90 Sb 10 As a buffer layer, Ag-Fe is a weldable bonding layer, and Bi... 0.07 Ge 0.9 Te is a P-type thermoelectric material.

2. The segmented thermoelectric device for electronic cooling according to claim 1, characterized in that, In the aforementioned N-type thermoelectric single leg, the thickness of the first N-type thermoelectric material is 2~4mm, the thickness of the second N-type thermoelectric material is 0.5~1mm, the thickness of the buffer layer is 0.1~0.3mm, and the thickness of the weldable connection layer is 0.4~0.8mm.

3. The segmented thermoelectric device for electronic cooling according to claim 1, characterized in that, In the P-type thermoelectric single leg, the thickness of the P-type thermoelectric material is 2~4mm, the thickness of the buffer layer is 0.1~0.3mm, and the thickness of the weldable connection layer is 0.4~0.8mm.

4. The segmented thermoelectric device for electronic cooling according to claim 1, characterized in that, The dimensions of the N-type thermoelectric single leg are (1~3) mm × (1~3) mm × (3~5) mm; the dimensions of the P-type thermoelectric single leg are (1~3) mm × (1~3) mm × (3~5) mm.

5. A method for fabricating a segmented thermoelectric device for electronic cooling as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Preparation of N-type thermoelectric single leg: S11, Mg 3.2 Bi 1.5 Sb 0.498 Te 0.002 Cu 0.01 The powder is loaded into a graphite mold and compacted, and then hot-pressed and sintered to obtain a block. S12, Bi2Te 2.694 Se 0.3 I 0.006 The powder was loaded into a graphite mold and compacted, and then hot-pressed and sintered to obtain block two; S13, Ag-Fe powder, Fe 90 Sb 10 The powder, block one, and block two are layered and packed into the graphite mold in the order of the N-type thermoelectric single leg composition and compacted. S14. Place the loaded graphite mold in a vacuum hot pressing device for hot pressing and sintering to obtain a block sample. S15. Cut the block sample to obtain an N-type thermoelectric single leg of the target size; S2. Preparation of P-type thermoelectric single leg: S21, Ag-Fe powder, Bi 0.07 Ge 0.9 Te powder, Fe 90 Sb 10 The powder was loaded into the graphite mold and compacted according to the P-type thermoelectric single-leg composition structure. S22. Place the loaded graphite mold in a spark plasma sintering equipment and perform spark plasma sintering to obtain a cylindrical sample. S23. Cut the cylindrical sample to obtain a P-type thermoelectric single leg of the target size; S3, gold plating, soldering, and assembly: The obtained N-type and P-type thermoelectric single legs are gold-plated and soldered, and then assembled with copper electrodes and alumina ceramic substrates to obtain segmented thermoelectric devices.

6. The method for fabricating a segmented thermoelectric device according to claim 5, characterized in that, In step S11, the hot pressing sintering temperature is 700~780K, the sintering pressure is 750~800Kg, and the sintering time is 15~35min; in step S12, the hot pressing sintering temperature is 500~580K, the sintering pressure is 600~680Kg, and the sintering time is 15~35min.

7. The method for fabricating a segmented thermoelectric device according to claim 5, characterized in that, In step S14, the hot pressing sintering temperature is 400~550K, the sintering pressure is 400~480Kg, and the sintering time is 60~70min.

8. The method for fabricating a segmented thermoelectric device according to claim 5, characterized in that, The cutting process conditions are as follows: the sample is cut using an electrical discharge machining (EDM) wire with a diameter of 0.35~0.45mm.

9. The method for fabricating a segmented thermoelectric device according to claim 5, characterized in that, After cutting, the material needs to be cleaned. The cleaning conditions are: ultrasonic cleaning with ethanol for 20-30 minutes.

10. The method for fabricating a segmented thermoelectric device according to claim 5, characterized in that, The copper electrode has a thickness of 0.1~0.3mm, and the alumina ceramic substrate has a thickness of 0.6~0.8mm and a size of 5~5.5mm×5~5.5mm.

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