Method for preparing multi-segment thermoelectric arms and multi-segment thermoelectric devices in batches

Abstract

The invention relates to a method for preparing multi-segment thermoelectric arms and multi-segment thermoelectric devices in batches. The method for preparing the multi-section thermoelectric arms in batches comprises the steps that at least one to-be-welded multi-section thermoelectric arm is placed between a heat source device and a cold source device, the temperature of the heat source device and the temperature of the cold source device are adjusted, meanwhile, the pressure applied to the to-be-welded thermoelectric arm through the heat source device and the cold source device is adjusted, and welding of the multi-section thermoelectric arm is achieved; the multi-segment thermoelectric arm to be welded is formed by combining at least two types of thermoelectric materials in different temperature zones along the temperature gradient direction, and a solder layer is arranged between every two adjacent types of thermoelectric materials. The at least two types of thermoelectric materials are at least two types of p-type thermoelectric materials or at least two types of n-type thermoelectric materials.

Description

Technical Field

[0001] The invention relates to a method for batch preparing multi-segment thermoelectric arms and multi-segment thermoelectric devices, belonging to the field of thermoelectric devices. Background Art

[0002] Thermoelectric power generation devices have the characteristics of no moving parts, environmental friendliness, long service life, and no need for light. They have broad application prospects in the fields of special power sources for deep space exploration, industrial waste heat utilization, and human body temperature power generation.

[0003] Energy conversion efficiency is an important output performance evaluation index of thermoelectric power generation devices. There are two main ways to improve energy conversion efficiency. On the one hand, methods of improving the thermoelectric figure of merit of materials by means of doping, alloying, nano-sizing, and composites have been widely adopted; designing and developing wide-temperature range thermoelectric devices that can work under a larger temperature difference is another way to improve energy conversion efficiency. Wide-temperature range thermoelectric devices use cascade or multi-stage structures to improve the average thermoelectric figure of merit of the device within a certain operating temperature difference, thereby improving the conversion efficiency. The structure of the cascade device is simple, but an intermediate insulating ceramic layer is introduced between the stages, resulting in large heat losses, and the total heat flow of the device is limited by the primary structure. In the multi-stage structure, the thermoelectric arms are connected by different thermoelectric materials, which is the main method currently adopted by wide-temperature range thermoelectric devices. Energy & Environmental Science 10 (2017) 956-963 The conversion efficiency of the dual-stage structure device using bismuth telluride and skutterudite materials reached 12% at a temperature difference of 541°C. Energy & Environmental Science 12 (2019) 3390-3399, the conversion efficiency of the dual-stage structure device using bismuth telluride and half-Heusler materials reached 13.3% at a temperature difference of 774K. Science 337 (2022) 208-213, the conversion efficiency of the dual-stage structure device using Bi2Te3 and germanium telluride materials reached 13.3% at a temperature difference of 506℃. Limited by the material use temperature and node temperature, the preparation of the above-mentioned dual-stage devices and the multi-stage thermoelectric devices proposed in Chinese Patent 1 (publication number CN107681044 A, 2018.02.09) is all top-down, that is, the high-temperature thermoelectric material / high-temperature electrode is connected to the thermoelectric materials in different temperature zones and then to the low-temperature electrode. Materials Science in Semiconductor Processing 13 (2010) 221-224 proposed a method for preparing a dual-stage thermoelectric device, in which the connection between the two thermoelectric materials is formed by superimposing powders and sintering in one step. Chinese Patent 2 (grant number CN105006517 B, 2017.12.12) proposed a multi-stage cascade thermoelectric device and its preparation method, in which the multi-stage thermoelectric columns are connected by a heat shielding layer and a brazing process, and the high-temperature end of the thermoelectric column is electrically connected and heat-conducted with the electrode by a mechanical contact method.

[0004] The preparation technology of the above-mentioned multi-segment device has the following disadvantages: in the process of top-down connection, problems such as solder extrusion and thermoelectric arm misalignment are prone to occur between blocks of different materials, which will deteriorate the performance of the device and even cause the device to short-circuit and fail, greatly reducing the device preparation yield. In addition, when materials in different temperature zones are connected, the p-type and n-type thermoelectric arms are welded at the same time, the welding temperature range is narrow, the process is difficult, and it is even difficult to select a suitable welding temperature when the welding temperature difference between the two materials is large. The one-time molding method of powder superposition sintering is sensitive to the sintering temperature, and the sintering temperatures of the two thermoelectric materials need to be close, which seriously limits the material selection space. Devices connected by high-temperature end mechanical contact have poor electrical and thermal contact, high performance loss, and reduced device efficiency.

[0005] Theoretically, thermoelectric devices prepared with three or more sections have higher energy conversion efficiency, but there are currently few publicly reported three-section or more section thermoelectric devices in the world. The increased complexity of the preparation process and process loss with the increase in the number of sections are one of the important reasons restricting its development. The preparation process of the existing two-section wide temperature range thermoelectric device is not suitable for low performance loss and batch preparation, and there is still a lack of suitable preparation process for three or more section thermoelectric devices. Summary of the invention

[0006] In view of the above problems, the present invention provides a method for batch preparation of multi-segment thermoelectric devices with simple process, flexible structure and integrally welded thermoelectric arms.

[0007] In a first aspect, the present invention provides a method for batch preparing multi-segment thermoelectric arms, comprising: placing at least one multi-segment thermoelectric arm to be welded between a heat source device and a cold source device, adjusting the temperature of the heat source device and the cold source device while adjusting the pressure applied to the thermoelectric arm to be welded by the heat source device and the cold source device, so as to achieve welding of the multi-segment thermoelectric arm; The multi-segment thermoelectric arm to be welded includes: at least two types of thermoelectric materials in different temperature zones are combined along the temperature gradient direction, and a solder layer is arranged between the two adjacent types of thermoelectric materials; the at least two types of thermoelectric materials are at least two types of p-type thermoelectric materials or at least two types of n-type thermoelectric materials. The method for batch preparation of multi-segment thermoelectric arms in the present invention greatly reduces the difficulty of preparing multi-segment thermoelectric arms. When preparing multi-segment thermoelectric arms, p-type thermoelectric materials in different temperature zones use columns with parallel upper and lower bottom surfaces, the same cross-sectional area and a larger size. Pressure is applied to both ends of the welded parts before and during welding to ensure that there is no obvious offset during pressure welding, and then the p-type multi-segment thermoelectric arm with the required cross-sectional area is obtained by cutting. Even if there is a small amount of offset, it will become scraps after cutting.

[0008] The multiple thermoelectric arms are obtained by connecting and cutting the temperature gradients of various thermoelectric materials in sequence. The temperature gradient descends in the direction from the high-temperature material to the low-temperature material.

[0009] Preferably, the p-type thermoelectric material is at least two of bismuth telluride, Mg3Sb2, germanium telluride, lead telluride, skutterudite, half-Heusler, silicon germanium, Zintle phase and lanthanum telluride; The n-type thermoelectric material is selected from at least two of bismuth telluride, Mg3Sb2, germanium telluride, lead telluride, skutterudite, half-Heusler, silicon germanium, Zintle phase and lanthanum telluride.

[0010] Preferably, the solder layer is in the form of a solder sheet, solder powder or solder paste; the material of the solder layer includes at least one of Sn-based solder, Bi-based solder, In-based solder, Cu-based solder and Ag-based solder, such as tin, copper and silver, and materials mainly composed of tin, copper and silver.

[0011] Preferably, the temperature of the heat source device is 300-900° C., the temperature of the cold source device is 10-60° C., and the insulation time is 1-60 minutes.

[0012] Preferably, when the at least two types of thermoelectric materials contain any one of silicon germanium, Zintle phase, and lanthanum telluride, the temperature of the heat source device is 650-900° C., the temperature of the cold source device is 10-60° C., and the insulation time is 1-60 minutes.

[0013] When the at least two types of thermoelectric materials are at least two types of materials selected from bismuth telluride, Mg3Sb2, germanium telluride, lead telluride, and skutterudite, the temperature is 300-650°C, the temperature of the cold source device is 10-60°C, and the insulation time is 1-60 minutes.

[0014] Preferably, the pressure applied to the thermoelectric arm to be welded by the heat source device and the cold source device is 1 MPa to 15 MPa.

[0015] Preferably, the upper surface and the bottom surface of the thermoelectric material are parallel and have the same shape, and the cross-sectional area is 15 mm 2 ~5000mm 2 , height is 0.5mm~20mm.

[0016] Preferably, a barrier layer is provided on the upper surface and / or the bottom surface of the thermoelectric material; the material of the barrier layer is selected from at least one of Ni, Fe, Co, Ti, Nb, Cr, Mo and W; and the thickness of the barrier layer is 50 to 300 μm.

[0017] In a second aspect, the present invention provides a multi-segment thermoelectric arm prepared according to the above method, wherein the multi-segment thermoelectric arm comprises: a p-type multi-segment thermoelectric arm and an n-type multi-segment thermoelectric arm.

[0018] In a third aspect, the present invention provides a method for preparing a multi-segment thermoelectric device, comprising: (1) After preparing a first high-temperature electrode solder layer and a second high-temperature electrode solder layer on the high-temperature end surfaces of the p-type multi-segment thermoelectric arm and the n-type multi-segment thermoelectric arm, respectively, a high-temperature electrode sheet is placed on the first high-temperature electrode solder layer and the second high-temperature electrode solder layer to form a π-shaped assembly as a thermoelectric unit to be welded; (2) placing at least one unit to be welded between a heat source device and a cold source device, adjusting the temperature of the heat source device and the cold source device while adjusting the pressure applied to the thermoelectric arm to be welded by the heat source device and the cold source device to achieve high temperature electrode welding; (3) Welding the low-temperature end of at least one thermoelectric unit to the low-temperature electrode sheet to form a multi-segment thermoelectric device. In the present invention, the technical difficulty of preparing the multi-segment thermoelectric device is that the connection process of the p-type multi-segment thermoelectric arm, the n-type multi-segment thermoelectric arm, the first high-temperature electrode solder layer, the second high-temperature electrode solder layer and the high-temperature electrode sheet requires the assistance of a mold to ensure the accuracy of the relative position.

[0019] Preferably, the first high-temperature electrode solder layer is in the form of a solder sheet, solder powder or solder paste, and the material of the first high-temperature electrode solder layer includes but is not limited to silver-based, copper-based and silver-copper alloy; The second high-temperature electrode solder layer is in the form of a solder sheet, solder powder or solder paste, and the material of the second high-temperature electrode solder layer includes but is not limited to silver-based, copper-based and silver-copper alloy.

[0020] Preferably, the material of the high-temperature electrode sheet includes: Cu, Ni, Cr, W, Mo and Fe; the material of the low-temperature electrode sheet includes: Cu, Ni, Mo and Fe.

[0021] Preferably, the temperature of the heat source device is 300-900°C, the temperature of the cold source device is 10-60°C, and the insulation time is 1-60 minutes; the pressure applied to the thermoelectric arm to be welded by the heat source device and the cold source device is 1MPa-15MPa.

[0022] In a fourth aspect, the present invention provides a multi-segment thermoelectric device prepared according to the above preparation method.

[0023] Beneficial effects of the present invention: The multi-segment thermoelectric arm in the present invention is prepared by integrated welding molding and cutting, which can greatly reduce the difficulty and time of preparing the multi-segment thermoelectric arm, and has the characteristics of batch preparation. There is a self-alignment effect between different materials and welding materials in the same type of thermoelectric arm, with a consistent cross-sectional area, and there is no problem of solder extrusion and misalignment between materials, which avoids problems such as short circuit and cold welding of the device, reduces the performance loss in the connection process of the multi-segment thermoelectric arm, and improves the yield of device preparation. The combination of each segment in the p-type and n-type thermoelectric arms (including the number of segments and the height ratio of each segment) is not restricted, which provides more possibilities for the preparation of high-conversion efficiency multi-segment devices. The high-temperature electrode connection adopts a temperature gradient welding method, where only the vicinity of the welding interface is at a high temperature, and the other parts are at a relatively low temperature, which can avoid the influence of high temperature on relatively low-temperature materials and interface performance. The preparation method of the multi-segment thermoelectric device provided by the present invention is simple in process, can realize the mass production of multi-segment thermoelectric devices, and promote the research and development process of multi-segment thermoelectric devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall structure of a multi-segment thermoelectric device consisting of 8 pairs of multi-segment thermoelectric arms; Figure 2 It is a schematic diagram of the structure of a single pair of multi-segment thermoelectric devices including a p-type multi-segment thermoelectric arm and an n-type multi-segment thermoelectric arm; Figure 3 It is a schematic diagram of a temperature gradient integrated welding method for a p-type multi-segment thermoelectric arm; Figure 4 It is a schematic diagram of the temperature gradient integrated welding method of n-type multi-segment thermoelectric arms; Figure 5 It is a schematic diagram of a method for welding high-temperature electrodes of a multi-stage thermoelectric device with a temperature gradient according to the present invention; Figure 6 It is a schematic diagram of a high-temperature electrode connection mold for a multi-segment thermoelectric device of the present invention; Figure 7 It is a schematic diagram of a method for connecting low-temperature electrodes of a multi-segment thermoelectric device according to the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, but not to limit the present invention.

[0026] In the present disclosure, p-type or n-type thermoelectric material blocks in different temperature zones are connected as a whole by welding under a temperature gradient, multiple sections of thermoelectric material blocks are cut to form p-type and n-type multi-section thermoelectric arms, and the p-type and n-type multi-section thermoelectric arms are connected to high-temperature electrodes under a temperature gradient to form multi-section thermoelectric pairs, which are then connected to low-temperature electrodes by welding. The thermoelectric materials include bismuth telluride, Mg3Sb2, germanium telluride, lead telluride, skutterudite, half-Heusler, silicon germanium, Zintle phase, and lanthanum telluride. There is a self-alignment effect between different materials in the same thermoelectric arm and between welding materials, which avoids short circuits and cold soldering problems, reduces process losses, and improves the yield of device preparation. The method for preparing a multi-section thermoelectric device provided by the present invention has a simple process, can realize batch preparation of multi-section thermoelectric devices, and accelerate the research and development process of multi-section thermoelectric devices.

[0027] Among them, thermoelectric material refers to a material that does not contain a barrier layer or a thermoelectric element containing a barrier layer. The height ratio of different thermoelectric materials in multiple p-type or n-type thermoelectric arms is not limited. Thermoelectric material blocks in different temperature zones are placed in sequence under a temperature gradient, and each interface is connected by integral welding to obtain multiple p-type or n-type thermoelectric material blocks. The materials of the high-temperature electrode and the low-temperature electrode include but are not limited to copper-based, nickel-based and other materials.

[0028] In an optional embodiment, the method of connecting the high-temperature electrode to the p-type and n-type thermoelectric arms is to connect to the high-temperature electrode under a temperature gradient through a welding process to form a multi-segment thermoelectric pair, and the high-temperature electrode interface is located on the high-temperature side. The multi-segment thermoelectric pairs are connected to the low-temperature electrode by low-temperature welding. The connection process between the multi-segment p-type or n-type thermoelectric arms and the high-temperature electrodes is carried out in any equipment that can provide a temperature gradient and pressure, including but not limited to commercial or self-built thermoelectric power generation device measurement systems, and the connection methods include but are not limited to soldering, brazing, and diffusion welding. The connection methods between the multi-segment thermoelectric arms and the low-temperature electrodes include but are not limited to soldering, brazing, and diffusion welding.

[0029] like Figure 1 As shown in FIG. 1 , the multi-segment thermoelectric device is composed of a plurality of multi-segment thermoelectric device basic units. Figure 2 As shown, in the p-type thermoelectric arm, the p-type high-temperature thermoelectric material 1 and the p-type medium-temperature thermoelectric material 2 are connected by a solder layer 4; the p-type medium-temperature thermoelectric material 2 and the p-type low-temperature thermoelectric material 3 are connected by a solder layer 5. In the n-type thermoelectric arm, the n-type high-temperature thermoelectric material 6 and the n-type medium-temperature thermoelectric material 7 are connected by a solder layer 9; the n-type medium-temperature thermoelectric material 7 and the n-type low-temperature thermoelectric material 8 are connected by a solder layer 10. The p-type and n-type multi-segment thermoelectric arms are connected to the high-temperature electrode 12 by a solder layer 11. The multi-segment thermoelectric pairs are connected to the low-temperature electrode 14 by a solder layer 13. Performance output is achieved by applying high temperature to the high-temperature electrode of the multi-segment thermoelectric device, applying low temperature to the low-temperature electrode, and connecting an external load.

[0030] The p-type high-temperature thermoelectric material 1 and the n-type high-temperature thermoelectric material 6 can be half-Heusler, silicon germanium, Zintle phase, lanthanum telluride and other materials. The p-type medium-temperature thermoelectric material 2 and the n-type medium-temperature thermoelectric material 7 can be skutterudite, lead telluride, germanium telluride and other materials. The p-type low-temperature thermoelectric material 3 and the n-type medium-temperature thermoelectric material 8 can be bismuth telluride, Mg3Sb2 and other materials. The thermoelectric materials in different temperature zones are pure thermoelectric materials or thermoelectric materials with barrier layers at both ends.

[0031] The solder layer 4 , the solder layer 5 , the solder layer 9 , the solder layer 10 , the solder layer 11 , and the solder layer 13 are in the form of solder flakes, solder powder, or solder paste.

[0032] The specific process of preparing the p-type multi-stage thermoelectric arm is to weld a large block of p-type high-temperature thermoelectric material 1, p-type medium-temperature thermoelectric material 2 and p-type low-temperature thermoelectric material 3 under a temperature gradient, such as Figure 3 As shown, the high-temperature thermoelectric material is in contact with the heat source 16, and the low-temperature thermoelectric material is in contact with the cold source 17. Heat is conducted to each interface between different thermoelectric materials, thereby completing welding. The bulk thermoelectric material and the connecting material in different temperature zones have similar cross-sectional areas and shapes, and the cross-sectional area size is 15mm 2 -5000mm 2 The bottom surfaces of the blocks are parallel and the height is 0.5mm-20mm. The welding methods are brazing, diffusion welding, etc. The welding process is carried out in a vacuum or inert gas atmosphere, the temperature of the heat source is 30℃-900℃, and the temperature of the cold source is 10℃-60℃. Axial pressure should be provided during welding, the size is 1MPa-15MPa, and the insulation time is 1 minute-60 minutes.

[0033] The specific process of preparing an n-type multi-stage thermoelectric device is to weld a bulk n-type high-temperature thermoelectric material 6, an n-type medium-temperature thermoelectric material 7 and an n-type low-temperature thermoelectric material 8 under a temperature gradient, such as Figure 4 As shown, the high-temperature thermoelectric material is in contact with the heat source 16, and the low-temperature thermoelectric material is in contact with the cold source 17. Heat is conducted to each interface between different thermoelectric materials, thereby completing welding. The bulk thermoelectric material and the connecting material in different temperature zones have similar cross-sectional areas and shapes, and the cross-sectional area size is 15mm 2 -5000mm 2 The bottom surfaces of the blocks are parallel and the height is 0.5mm-20mm. The welding methods are brazing, diffusion welding, etc. The welding process is carried out in a vacuum or inert gas atmosphere, the temperature of the heat source is 30℃-900℃, and the temperature of the cold source is 10℃-60℃. Axial pressure should be provided during welding, the size is 1MPa-15MPa, and the insulation time is 1 minute-60 minutes.

[0034] The welded multi-section thermoelectric material blocks are cut by diamond disc cutting, diamond wire cutting, and electric spark wire cutting. Figure 3 As shown, after cutting, batches of p-type multi-segment thermoelectric arms are obtained; Figure 4 As shown, after cutting, batches of n-type multi-segment thermoelectric arms are obtained.

[0035] like Figure 5 As shown, the p-type and n-type multi-segment thermoelectric arms obtained by cutting are connected to the high-temperature electrode. The connection process is carried out under a temperature gradient. The high-temperature electrode 12 is in contact with the heat source 16, and the low-temperature end of the multi-segment thermoelectric arm is in contact with the cold source 17. There is a solder layer 11 between the p-type multi-segment thermoelectric arm and the high-temperature electrode, and between the n-type multi-segment thermoelectric arm and the high-temperature electrode. Multiple groups of multi-segment thermoelectric arms are connected by Figure 6 The high temperature limit plate 18, limit column 19 and low temperature limit plate 20 shown are positioned. The temperature of the heat source is 30℃-900℃, and the temperature of the cold source is 10℃-60℃. The heat reaches the interface between the multi-segment thermoelectric arm and the high temperature electrode through heat conduction, but has no significant effect on the interface at the lower temperature, thereby completing the welding. The welding process is carried out in a vacuum or inert gas atmosphere. Axial pressure should be provided during welding, the size is 1MPa-15MPa, and the insulation time is 1 minute-60 minutes.

[0036] like Figure 7 As shown, the multiple-segment thermoelectric pairs are connected to the low-temperature electrode through the solder layer 13. The welding is carried out by tin soldering, silver paste welding, etc. The heating plate 12 provides the required temperature for welding. The welding process is carried out in air, protective gas or vacuum. After welding, a multiple-segment thermoelectric device is obtained.

[0037] The following further examples are given to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0038] Example 1 Batch preparation of p-type multi-segment thermoelectric arms: like Figure 3 As shown, the p-type high temperature thermoelectric material is a half-Heusler material, specifically Nb 0.86 Hf 0.14 FeSb material; p-type medium-temperature thermoelectric material selects germanium telluride material, specifically Ge 0.89 Cu 0.06 Sb 0.08 Te; p-type low-temperature thermoelectric material selects bismuth telluride material, specifically Bi1.8 Sb 0.2 Te3.

[0039] The blocks of p-type half-Heusler material, p-type germanium telluride material and p-type bismuth telluride material are all columnar materials with a diameter of 30 mm, which are obtained by hot pressing sintering or ingot casting. First, the operating temperature of the thermoelectric device is determined to be 850°C at the high temperature end and 25°C at the low temperature end. Through finite element simulation or one-dimensional heat conduction calculation, it can be determined that the height of the p-type half-Heusler material is 10 mm, the height of the p-type germanium telluride material is 5 mm, and the height of the p-type bismuth telluride material is 2 mm. The thermoelectric material column of the corresponding height is obtained by grinding. Figure 3 As shown, p-type bismuth telluride material, Sn-based paste solder, p-type germanium telluride material, Cu-based solder sheet with a diameter of 30 mm, and p-type half-Heusler material are placed in order from bottom to top and placed between the heat source 16 and the cold source 17. The heat source and the p-type half-Heusler material are in contact with each other through high thermal conductivity carbon paper, and the cold source and the p-type bismuth telluride material are in contact with each other through high thermal conductivity carbon paper. A pressure of 3MPa is applied between the heat source and the cold source, the temperature of the heat source is increased to 800°C, and the temperature of the cold source is maintained at 30°C. The device used here to provide this condition is the thermoelectric device output performance test system PEM-2. After 10 minutes of heat preservation, the temperature of the heat source and the cold source is reduced to 25°C, and finally a p-type multi-segment thermoelectric material block is obtained. The p-type multi-segment thermoelectric material block is cut by electric spark cutting to obtain a large number of p-type multi-segment thermoelectric arms with a cross-sectional area of ​​4mm×4mm.

[0040] Example 2 Batch preparation of n-type multi-segment thermoelectric arms: like Figure 4 As shown, the n-type high temperature thermoelectric material is a half-Heusler material, specifically Zr 0.5 Hf 0.5 NiSn 0.985 Sb 0.015 Materials: The n-type medium-temperature thermoelectric material is selected from skutterudite materials, specifically Yb 0.3 4Sb 12 ; The n-type low-temperature thermoelectric material is selected from Mg3Sb2 material, specifically Mg3SbBi.

[0041] The blocks of n-type half-Heusler material, n-type skutterudite material and n-type Mg3Sb2 material are all columnar materials with a diameter of 30 mm, which are obtained by hot pressing sintering or ingot casting. The working temperature of the thermoelectric device is determined to be 850°C at the high temperature end and 25°C at the low temperature end. Finite element simulation or one-dimensional heat conduction calculation can determine that the height of the n-type half-Heusler material is 9 mm, the height of the n-type skutterudite material is 7.2 mm, and the height of the n-type Mg3Sb2 material is 1.8 mm. The thermoelectric material column of corresponding height is obtained by grinding. Figure 4As shown, n-type Mg3Sb2 material, Sn-based paste solder, n-type skutterudite material, Cu-based solder sheet with a diameter of 30 mm and n-type half-Heusler material are placed in order from bottom to top and placed between the heat source 16 and the cold source 17. The heat source and the n-type half-Heusler material are in contact with each other through high thermal conductivity carbon paper, and the cold source and the n-type Mg3Sb2 material are in contact with each other through high thermal conductivity carbon paper. A pressure of 3MPa is applied between the heat source and the cold source, the temperature of the heat source is increased to 800°C, and the temperature of the cold source is maintained at 30°C. The device used here to provide this condition is the thermoelectric device output performance test system PEM-2. After 10 minutes of heat preservation, the temperature of the heat source and the cold source is reduced to 25°C, and finally an n-type multi-segment thermoelectric material block is obtained. The n-type multi-segment thermoelectric material block is cut by electric spark cutting to obtain a large number of n-type multi-segment thermoelectric arms with a cross-sectional area of ​​4mm×4mm.

[0042] Example 3 Preparation of multi-stage thermoelectric device (1) Figure 5 As shown, the p-type multi-segment thermoelectric arm prepared in Example 1 and the n-type multi-segment thermoelectric arm prepared in Example 2 are placed in the middle part of the low-temperature end limiting mold 20 in the order of pnpn, and then four limiting columns 19 are placed in the corresponding holes on the edge of the limiting mold, and the high-temperature end limiting mold 18 is placed on the limiting columns 19 and positioned by the limiting columns 19. A Cu-based welding sheet with a cross-sectional area of ​​4mm×4mm is placed on the p-type multi-segment thermoelectric arm, and a Cu-based welding sheet with a cross-sectional area of ​​4mm×4mm is placed on the n-type multi-segment thermoelectric arm. A Cu electrode with a size of 4.5mm×9mm×1mm is placed above the welding sheet and positioned by the high-temperature end limiting mold. High thermal conductivity carbon paper is placed on the cold source, and the above-mentioned thermoelectric unit to be welded is placed thereon. High thermal conductivity carbon paper is placed on the upper surface of the thermoelectric unit to be welded to reduce the thermal resistance between the unit to be welded and the heat source. As shown Figure 5 As shown, an initial pressure of 0.5 MPa is applied between the heat source 16 and the cold source 17, the cold source temperature is kept at 25°C, the heat source temperature is increased from room temperature to 860°C, and the pressure is increased to 3 MPa. After maintaining the temperature and pressure for 10 minutes, the heat source temperature is slowly reduced to room temperature, and the pressure is slowly reduced to below 0.5 MPa. The high-temperature end limit mold 18, the limit column 19 and the low-temperature end limit mold 20 are removed in sequence to obtain 8 π-shaped thermoelectric elements consisting of p-type multi-segment thermoelectric arms, n-type multi-segment thermoelectric arms and copper electrodes.

[0043] (2) Apply paste tin-based solder to the low-temperature ends of the eight π-shaped thermoelectric elements and place them on the copper-clad alumina ceramic plate 15, with element 14 as the low-temperature end electrode material. Place the assembly on a flat heater 21 and apply an axial pressure of 2 MPa. Raise the temperature of the flat heater to 230°C, keep it warm for 2 minutes, and cool it to room temperature to complete the low-temperature end welding of the three-stage thermoelectric device, and finally obtain a three-stage thermoelectric device composed of p-bismuth telluride / germanium telluride / half-Heusler and n-Mg3Sb2 / skutterudite / half-Heusler materials.

Claims

1. A method for batch preparation of multi-segment thermoelectric arms, characterized in that: include: Place at least one multi-segment thermoelectric arm to be welded between a heat source device and a cold source device, adjust the temperature of the heat source device and the cold source device, and adjust the pressure applied to the thermoelectric arm to be welded by the heat source device and the cold source device, so as to achieve welding of the multi-segment thermoelectric arm; The multi-segment thermoelectric arm to be welded comprises: at least two types of thermoelectric materials in different temperature zones are combined along the temperature gradient direction, and a solder layer is arranged between two adjacent types of thermoelectric materials; The at least two types of thermoelectric materials are at least two types of p-type thermoelectric materials or at least two types of n-type thermoelectric materials.

2. The method for batch preparing thermoelectric arms according to claim 1, characterized in that: The p-type thermoelectric material is selected from at least two of bismuth telluride, Mg3Sb2, germanium telluride, lead telluride, skutterudite, half-Heusler, silicon germanium, Zintle phase and lanthanum telluride; The n-type thermoelectric material is selected from at least two of bismuth telluride, Mg3Sb2, germanium telluride, lead telluride, skutterudite, half-Heusler, silicon germanium, Zintle phase and lanthanum telluride.

3. The method for batch preparing thermoelectric arms according to claim 1, characterized in that: The solder layer is in the form of solder flakes, solder powder or solder paste; the material of the solder layer includes at least one of Sn-based solder, Bi-based solder, In-based solder, Cu-based solder and Ag-based solder.

4. The method for batch preparing thermoelectric arms according to claim 1, characterized in that: The temperature of the heat source device is 300-900° C., the temperature of the cold source device is 10-60° C., and the heat preservation time is 1-60 minutes.

5. The method for batch preparing thermoelectric arms according to claim 4, characterized in that: When the at least two types of thermoelectric materials include any one of silicon germanium, Zintle phase, and lanthanum telluride, the temperature of the heat source device is 650-900° C., the temperature of the cold source device is 10-60° C., and the insulation time is 1-60 minutes; When the at least two types of thermoelectric materials are at least two types of materials selected from bismuth telluride, Mg3Sb2, germanium telluride, lead telluride, and skutterudite, the temperature is 300-650°C, the temperature of the cold source device is 10-60°C, and the insulation time is 1-60 minutes.

6. The method for batch preparing thermoelectric arms according to claim 1, characterized in that: The pressure applied to the thermoelectric arm to be welded by the heat source device and the cold source device is 1MPa to 15MPa.

7. The method for batch preparing thermoelectric arms according to claim 1, characterized in that: The upper surface and the bottom surface of the thermoelectric material are parallel and have the same shape, and the cross-sectional area is 15 mm 2 ~5000mm 2 , height is 0.5mm~20mm.

8. The method for batch preparing thermoelectric arms according to claim 7, characterized in that: A barrier layer is arranged on the upper surface and / or the bottom surface of the thermoelectric material; the material of the barrier layer is selected from at least one of Ni, Fe, Co, Ti, Nb, Cr, Mo and W; the thickness of the barrier layer is 50 to 300 μm.

9. A multi-segment thermoelectric arm prepared according to the method of any one of claims 1 to 8, the multi-segment thermoelectric arm comprising: p-type multi-segment thermoelectric arm and n-type multi-segment thermoelectric arm.

10. A method for preparing a multi-segment thermoelectric device, characterized in that: include: (1) After preparing a first high-temperature electrode solder layer and a second high-temperature electrode solder layer on the high-temperature end surfaces of the p-type multi-segment thermoelectric arm and the n-type multi-segment thermoelectric arm, respectively, a high-temperature electrode sheet is placed on the first high-temperature electrode solder layer and the second high-temperature electrode solder layer to form a π-shaped assembly as a thermoelectric unit to be welded; (2) placing at least one unit to be welded between a heat source device and a cold source device, adjusting the temperature of the heat source device and the cold source device while adjusting the pressure applied to the thermoelectric arm to be welded by the heat source device and the cold source device to achieve high temperature electrode welding; (3) Welding the low-temperature end of at least one thermoelectric unit to the low-temperature electrode sheet to form a multi-stage thermoelectric device.

11. The preparation method according to claim 10, characterized in that: The first high-temperature electrode solder layer is in the form of a solder sheet, solder powder or solder paste, and the material of the first high-temperature electrode solder layer includes Ag-based and Cu-based solders; The second high-temperature electrode solder layer is in the form of a solder sheet, solder powder or solder paste, and the material of the second high-temperature electrode solder layer includes Ag-based and Cu-based solders.

12. The preparation method according to claim 10, characterized in that: The materials of the high-temperature electrode sheet include: Cu, Ni, Cr, W, Mo and Fe; the materials of the low-temperature electrode plate include: Cu, Ni, Mo and Fe.

13. The preparation method according to any one of claims 10 to 12, characterized in that: The temperature of the heat source device is 300-900°C, the temperature of the cold source device is 10-60°C, and the insulation time is 1-60 minutes; the pressure applied to the thermoelectric arm to be welded by the heat source device and the cold source device is 1MPa-15MPa.

14. A multi-segment thermoelectric device prepared according to the preparation method according to any one of claims 10 to 13.

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