Barrier layer for bismuth telluride-based thermoelectric device, bismuth telluride-based thermoelectric device and preparation method and application of bismuth telluride-based thermoelectric device

Abstract

The invention provides a barrier layer for a bismuth telluride-based thermoelectric device, the bismuth telluride-based thermoelectric device and a preparation method and application of the bismuth telluride-based thermoelectric device, and relates to the technical field of thermoelectric devices. Materials adopted by the barrier layer for the bismuth telluride-based thermoelectric device comprise NiSbTe3, and due to the fact that NiSbTe3 is one of thermodynamic stable phases of a Bi2 / (Se, Te) 3-NiSbTe3-Sb2Te3 phase region, NiSbTe3 does not react with a bismuth telluride thermoelectric material at an interface to generate other harmful impurity phases at the temperature of 473 K or above; in addition, the intrinsic resistivity of NiSbTe3 is low, the linear thermal expansion coefficient of NiSbTe3 is close to that of bismuth telluride, and the barrier layer prepared through sintering and the bismuth telluride material have the advantages of being high in binding force, low in contact resistivity and the like. The bismuth telluride-based thermoelectric device adopting the NiSbTe3 barrier layer has excellent thermoelectric conversion performance and extremely excellent thermal stability.

Description

Technical Field

[0001] The present invention relates to the technical field of thermoelectric devices, and in particular to a barrier layer for a bismuth telluride-based thermoelectric device, a bismuth telluride-based thermoelectric device, and a preparation method and application thereof. Background Art

[0002] Thermoelectric conversion technology achieves direct conversion of heat and electricity through the Seebeck effect in semiconductor materials. The core of thermoelectric technology lies in the thermoelectric device. A thermoelectric device typically consists of a p / n-type thermoelectric material, an alloyed diffusion barrier, a solder layer, metal electrodes, and a ceramic insulated circuit board. The hot end of a thermoelectric device is constantly exposed to high temperatures during operation. Because the thermoelectric material is in direct contact with the Sn-based solder and the Cu electrode, intense chemical reactions or atomic diffusion readily occur at the interface under high temperature conditions. These chemical reactions or atomic diffusion at this interface, on the one hand, act as a secondary doping agent for the thermoelectric material, causing it to deviate from its optimal carrier concentration and degrade its performance. On the other hand, this interdiffusion reaction of elements can lead to the formation of brittle compounds at the electrode junction, significantly increasing interfacial resistance and potentially causing brittle fracture at the interface, leading to device failure. Therefore, a barrier layer is needed on the surface of the thermoelectric material to inhibit interdiffusion and reactions between the different materials during subsequent soldering and service, ensuring the long-term stability of the device structure and performance.

[0003] The alloyed diffusion barrier layer of thermoelectric devices needs to have properties such as low contact resistance, high bonding strength, and high thermal stability. Metallic nickel has long been used as a barrier layer material for bismuth telluride thermoelectric cooling modules due to its low price, stable performance, and thermal expansion coefficient similar to that of bismuth telluride. The ideal interface resistivity of metallic nickel is approximately 10 μΩcm. 2 However, when the hot end of a thermoelectric module is used above 473K, brittle intermetallic compounds are formed between the Ni barrier layer and the bismuth telluride matrix through elemental diffusion. This not only dramatically increases the contact resistance between the barrier layer and the matrix, but also increases the risk of interfacial cracking and failure due to the mismatch in thermal expansion coefficients. Although barrier layers such as Fe and Ti have emerged in recent years, they have not yet demonstrated comprehensive device service characteristics above 473K, including low contact resistance, high bonding strength, and high thermal stability. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a barrier layer for a bismuth telluride-based thermoelectric device, a bismuth telluride-based thermoelectric device, and a preparation method and application thereof. The barrier layer still has low contact resistance, high bonding strength and high thermal stability at temperatures above 473 K, solving the problem that the elemental Ni barrier layer in existing bismuth telluride-based thermoelectric devices cannot simultaneously achieve long-term thermal stability, high bonding strength and low contact resistance at temperatures above 473 K.

[0005] The specific technical solutions of the present invention are: In a first aspect, the present invention provides a barrier layer for a bismuth telluride-based thermoelectric device, wherein the material of the barrier layer includes NiSbTe3.

[0006] The barrier layer for bismuth telluride-based thermoelectric devices provided by the present invention uses materials including NiSbTe3. Since NiSbTe3 is one of the thermodynamically stable phases in the Bi2 / (Se,Te)3-NiSbTe3-Sb2Te3 phase region, NiSbTe3 will not react with the bismuth telluride thermoelectric material at the interface to generate other harmful impurity phases at temperatures above 473 K. At the same time, within the entire service temperature range of the bismuth telluride thermoelectric device, NiSbTe3 has a linear thermal expansion coefficient similar to that of bismuth telluride, avoiding the generation of thermal stress at high temperatures. Due to the combined action of the temperature field and pressure field of NiSbTe3 and bismuth telluride during the sintering process, the atoms at the interface will interlock with each other, thereby improving the bonding strength between the barrier layer and the thermoelectric material. In addition, NiSbTe3 also has a low intrinsic resistivity of approximately 100 μΩ cm. After high-strength and high-stability bonding, it also has a low contact resistivity between it and the bismuth telluride material over the entire temperature range.

[0007] In a second aspect, the present invention further provides a bismuth telluride-based thermoelectric device using the above-mentioned barrier layer.

[0008] In a third aspect, the present invention further provides a method for preparing the above-mentioned bismuth telluride-based thermoelectric device, comprising the following steps: S1, NiSbTe3 material and p-type bismuth telluride-based material are sintered to form a NiSbTe3 barrier layer on the hot end surface of the p-type bismuth telluride-based material to obtain a NiSbTe3 / p-type bismuth telluride sample; S2, NiSbTe3 material and n-type bismuth telluride-based material are sintered to form a NiSbTe3 barrier layer on the hot end surface of the n-type bismuth telluride-based material, thereby obtaining a NiSbTe3 / n-type bismuth telluride sample; S3. A nickel barrier layer is plated on the cold end surface of the NiSbTe3 / p-type bismuth telluride sample described in step S1 and the cold end surface of the NiSbTe3 / n-type bismuth telluride sample described in step S2, and then the cold end surfaces are cut and welded on a substrate to obtain a bismuth telluride-based thermoelectric device.

[0009] The present invention provides a method for preparing a bismuth telluride-based thermoelectric device, which constructs a NiSbTe3 barrier layer by directly sintering NiSbTe3 on the surface of p-type bismuth telluride powder or n-type bismuth telluride block, so that the interface stress between the prepared barrier layer and the p-type bismuth telluride powder or n-type bismuth telluride is small, and under the combined action of the temperature field and the pressure field during the sintering process, the atoms at the interface will bite each other, thereby improving the bonding strength between the barrier layer and the thermoelectric material, so that the mechanical structure of the prepared bismuth telluride-based thermoelectric device is stable when it serves in typical working conditions such as long-term high temperature and hot and cold alternation.

[0010] In the present invention, the hot end of the p-type bismuth telluride-based material and the hot end of the n-type bismuth telluride-based material refer to the end used for thermoelectric conversion in a high-temperature environment after the p-type bismuth telluride-based material and the n-type bismuth telluride-based material are assembled into a thermoelectric device; the cold end of the NiSbTe3 / p-type bismuth telluride sample and the cold end of the NiSbTe3 / n-type bismuth telluride sample refer to the end used for thermoelectric conversion in a low-temperature environment after the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample are assembled into a thermoelectric device.

[0011] In one possible embodiment, the sintering treatment in step S1 and step S2 is performed under an atmosphere of N2, a pressure of 50-100 MPa, and a temperature of 673-723 K.

[0012] In a possible implementation manner, the sintering treatment time in step S1 is 3-20 minutes.

[0013] In a possible implementation manner, the sintering treatment time in step S2 is 10-20 minutes.

[0014] In one possible embodiment, the p-type bismuth telluride-based material is Bi co-doped with Ag, Cu, Cd, Mn, Mg, Ca and S. 0.4 Sb 1.6 Te3.

[0015] In one possible embodiment, the p-type bismuth telluride-based material is Bi co-doped with Ag, Cu, Cd, Mn, Mg, Ca and Se. 0.5 Sb 1.5 Te3.

[0016] In one possible embodiment, the n-type bismuth telluride-based material is Bi2Te doped with one or two of BiCl3, AgI, SbI3, PbI2 and TeI4. 2.65 Se 0.35 .

[0017] In one possible embodiment, the n-type bismuth telluride-based material is Bi2Te doped with one or two of BiCl3, AgI, SbI3, PbI2 and TeI4. 2.7 Se 0.3 .

[0018] In one possible embodiment, the sintering process described in step S1 is to place NiSbTe3 powder in a graphite mold and flatten it to obtain a NiSbTe3 layer, place p-type bismuth telluride-based material powder on the NiSbTe3 layer and flatten it to obtain a NiSbTe3 / p-type bismuth telluride preform, and then sinter the NiSbTe3 / p-type bismuth telluride preform under N2 atmosphere, 50-100 MPa pressure and 673-723 K temperature conditions for 3-20 min.

[0019] In one possible embodiment, the sintering process described in step S2 is to place NiSbTe3 powder in a graphite mold and flatten it to obtain a NiSbTe3 layer, place an n-type bismuth telluride-based block on the NiSbTe3 layer and flatten it to obtain a NiSbTe3 / n-type bismuth telluride preform, and then sinter the NiSbTe3 / n-type bismuth telluride preform in an N2 atmosphere, a pressure of 50-100 MPa and a temperature of 673-723K for 10-30 min.

[0020] Furthermore, the particle size distribution range of the NiSbTe3 powder is 10-100 μm.

[0021] Furthermore, the particle size of the p-type bismuth telluride-based material powder is 200 nm-2 μm.

[0022] Furthermore, the n-type bismuth telluride-based block is a bismuth telluride-based block with a diameter of 20-30 mm obtained by a zone melting method.

[0023] In a possible implementation manner, the process of plating the nickel barrier layer in step S3 includes wax immersion protection, corrosion, and electroplating.

[0024] Furthermore, the wax immersion protection process is to immerse the hot ends of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample in melted low-temperature wax respectively, and the low-temperature wax solidifies on the surface of the hot end to form a protective layer.

[0025] Furthermore, the corrosion process is to immerse the cold ends of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample in a mixed acid solution composed of hydrochloric acid, nitric acid and water, corrode for 3-5 minutes, and then ultrasonically clean them in an ethanol solution to obtain the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after corrosion treatment.

[0026] Furthermore, the mass percentage of the hydrochloric acid is 60-70% hydrochloric acid, and the mass percentage of the nitric acid is 85-98% nitric acid.

[0027] Furthermore, in the mixed acid solution, the volume ratio of the hydrochloric acid to the nitric acid is 1:(3-4), and the volume ratio of the hydrochloric acid to the water is 1:(4-6).

[0028] Furthermore, the electroplating process is to immerse the NiSbTe3 / p-type bismuth telluride sample after corrosion treatment and the NiSbTe3 / n-type bismuth telluride sample in an electroplating solution containing Ni(NH2SO3)2, NiCL·6H2O, H3BO3 and a solvent as a cathode, and use a single Ni plate as an anode at a temperature of 313-318 K for electroplating for 20-40 minutes.

[0029] Furthermore, in the electroplating solution, the concentration of Ni(NH2SO3)2 is 250-350 g / L, the concentration of NiCL·6H2O is 15-40 g / L, and the concentration of H3BO3 is 20-40 g / L.

[0030] Furthermore, the solvent in the electroplating solution is water.

[0031] In one possible embodiment, the welding process in step S3 is to use Cu-coated alumina ceramic as the upper substrate and the lower substrate, the upper substrate is connected to the NiSbTe3 barrier layer through SnPbAg solder, and the lower substrate is connected to the nickel barrier layer through SnBi solder.

[0032] In a fourth aspect, the present invention also provides applications of the above-mentioned bismuth telluride-based thermoelectric device in the field of thermoelectric conversion.

[0033] The above embodiments can be combined arbitrarily based on the common knowledge in this field.

[0034] The reagents and raw materials used in the present invention are commercially available.

[0035] The positive progress effect of the present invention is: The barrier layer for thermoelectric devices provided by the present invention uses NiSbTe3 material, which enables the barrier layer to still have low contact resistance, high bonding strength and high thermal stability at temperatures above 473 K. The contact resistivity of the NiSbTe3 barrier layer and the p / n-type bismuth telluride heterojunction can be as low as 5 μΩ cm 2 The contact resistance remained essentially unchanged after 30 days of continuous annealing at 523 K, ensuring the stability of the bismuth telluride-based thermoelectric device. The difference in thermal expansion coefficient between the NiSbTe3 barrier layer and the bismuth telluride substrate was within 20% across the entire service temperature range of the bismuth telluride-based thermoelectric device, significantly superior to that of the Ti barrier layer. Compared to the conventional electroplated Ni barrier layer, the shear and tensile strengths of the NiSbTe3 barrier layer increased by more than five times, reaching 5 MPa and 10 MPa, respectively. The bismuth telluride-based thermoelectric device fabricated with the NiSbTe3 barrier layer maintained a stable output power and conversion efficiency of 0.83 W and 6.8%, respectively, after 15 days of service at a hot-end temperature of 540 K and a cold-end temperature of 285 K. These results demonstrate that the device exhibits excellent thermoelectric performance and exceptional thermal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a scanning electron microscope image of the NiSbTe3 / p-type bismuth telluride sample prepared in Example 1 at the two-phase interface after annealing and the corresponding line scanning elemental map.

[0037] Figure 2 This is a graph showing the contact resistance test data of the NiSbTe3 / p-type bismuth telluride sample prepared in Example 1 before and after annealing.

[0038] Figure 3 This is a comparison chart of the contact resistivity of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample prepared in Example 1 after annealing and the contact resistance values ​​of samples using other materials as barrier layers.

[0039] Figure 4 The figure compares the test data of linear thermal expansion coefficient of NiSbTe3 material alone, p-type bismuth telluride, and n-type bismuth telluride.

[0040] Figure 5 This is a comparison chart of the shear strength and tensile strength test data of the NiSbTe3 barrier layer and the Ni barrier layer on the bismuth telluride substrate.

[0041] Figure 6 This is a physical picture of the bismuth telluride-based thermoelectric device prepared in Example 1.

[0042] Figure 7Graph showing the conversion efficiency of the bismuth telluride-based thermoelectric device prepared in Example 1 after 100 cycles at hot-end temperatures of 540 K, 478 K, and 416 K.

[0043] Figure 8 This is a graph showing the output power and conversion efficiency data of the bismuth telluride-based thermoelectric device prepared in Example 1 after serving for 15 days at a hot-end temperature of 540 K and a cold-end temperature of 285 K. DETAILED DESCRIPTION

[0044] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only intended to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter ranges described in the present invention. Reasonable variations derived therefrom are still within the scope of protection of the claims of the present invention.

[0045] It should be noted that the endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0046] Unless otherwise defined, all terms, symbols and other scientific terms used herein are intended to have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In some cases, terms with conventional meanings are defined herein for the purpose of clarification or ease of reference, and such definitions herein should not be construed as indicating significant differences from conventional understandings in the art. The technical methods described or cited herein are generally well understood by those skilled in the art and are adopted by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents and instruments was carried out in accordance with the protocols and parameters given by the manufacturers.

[0047] Example 1

[0048] This embodiment provides a bismuth telluride-based thermoelectric device, which is composed of a p / n-type bismuth telluride-based thermoelectric material, a barrier layer, a solder layer, a metal electrode, and a ceramic insulating circuit board, wherein the barrier layer is made of NiSbTe3; It is prepared by the following method: (1) 1 g of NiSbTe3 powder with a particle size of 50±10 μm was placed in a graphite mold and flattened to obtain a NiSbTe3 layer; 25 g of p-type bismuth telluride-based material powder with a particle size of 1000±300 nm was placed on the NiSbTe3 layer and flattened. The components of the p-type bismuth telluride-based material are Bi0.4 Sb 1.592 Cd 0.008 Te3, to obtain NiSbTe3 / p-type bismuth telluride layered powder, which was then sintered in N2 atmosphere, 60 MPa pressure and 693 K temperature for 8 min to obtain a NiSbTe3 / p-type bismuth telluride sample with a NiSbTe3 barrier layer on one end. The NiSbTe3 / p-type bismuth telluride sample had a height of 5 mm and a diameter of 25 mm after leveling. (2) 1 g of NiSbTe3 powder with a particle size of 50±10 μm was placed in a graphite mold and flattened to obtain a NiSbTe3 layer. 28 g of n-type bismuth telluride-based region frit material with a diameter of 25 mm was placed on the NiSbTe3 layer and flattened. The specific composition of the n-type bismuth telluride-based region frit material is Bi2Te 2.65 Se 0.35 + 0.12wt% AgI to obtain NiSbTe3 / n-type bismuth telluride, which was then sintered for 20 min in an N2 atmosphere at a pressure of 80 MPa and a temperature of 713 K to obtain a NiSbTe3 / n-type bismuth telluride sample with a NiSbTe3 barrier layer at one end. The NiSbTe3 / n-type bismuth telluride sample had a height of 5 mm and a diameter of 25 mm after leveling. (3) immersing the hot ends of the NiSbTe3 / p-type bismuth telluride sample in step (1) and the NiSbTe3 / n-type bismuth telluride sample in step (2) into melted low-temperature wax, respectively, so that the low-temperature wax solidifies on the surface of the hot end to form a protective layer; (4) At an ambient temperature of 303 K, the cold ends of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after completing step (3) are immersed in a mixed acid solution consisting of hydrochloric acid, nitric acid and water for 4 minutes, wherein the mass percentage of hydrochloric acid is 65%, the mass percentage of nitric acid is 90%, the volume ratio of 65% hydrochloric acid to 90% nitric acid in the mixed acid solution is 1:3.5, and the volume ratio of 65% hydrochloric acid to water is 1:5. Then, ultrasonic cleaning is carried out in an ethanol solution to obtain the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after corrosion treatment; (5) Under the temperature condition of 315K, the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after the corrosion treatment in step (4) are immersed in an electroplating solution containing Ni(NH2SO3)2, NiCl·6H2O, H3BO3 and solvent as the cathode, and a single Ni plate is used as the anode. The electroplating treatment is carried out for 30 minutes. The concentration of Ni(NH2SO3)2 in the electroplating solution is 300 g / L, the concentration of NiCl·6H2O is 25 g / L, and the concentration of H3BO3 is 30 g / L, thereby obtaining NiSbTe3 / p-type bismuth telluride sample and NiSbTe3 / n-type bismuth telluride sample with a NiSbTe3 barrier layer at the hot end and a Ni barrier layer at the cold end; (6) The NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample that have completed step (5) are cut into thermoelectric arm particles by a dicing machine. The length and width of the thermoelectric arm particles are both 2.3 mm. Then, Cu-coated alumina ceramics are used as the upper substrate and the lower substrate respectively. The size of the upper substrate and the lower substrate are 20 mm×20 mm×0.3 mm. The upper substrate is the hot end, and 17 Cu electrodes with a size of 2.5 mm×2.5 mm×0.6 mm are attached. 92.5 Ag 2.5 The solder is connected to the NiSbTe3 barrier layer end, and the soldering temperature is 603 K; the lower substrate is the cold end, and 18 Cu electrodes with a size of 2.5 mm × 2.5 mm × 0.6 mm are attached. 42 Bi 58 The solder was connected to the Ni barrier layer at a soldering temperature of 423 K. The solder was kept at this temperature for 3 minutes and then transferred to a 303 K constant temperature water cooling plate to cool to room temperature. Copper wires were then soldered to lead out the electrodes to obtain a bismuth telluride-based thermoelectric device.

[0049] Example 2 This embodiment provides a bismuth telluride-based thermoelectric device, which is composed of a p / n-type bismuth telluride-based thermoelectric material, a barrier layer, a solder layer, a metal electrode, and a ceramic insulating circuit board, wherein the barrier layer is made of NiSbTe3; It is prepared by the following method: (1) 1 g of NiSbTe3 powder with a particle size of 50±10 μm was placed in a graphite mold and flattened to obtain a NiSbTe3 layer; 25 g of p-type bismuth telluride-based material powder with a particle size of 1000±300 nm was placed on the NiSbTe3 layer and flattened. The components of the p-type bismuth telluride-based material are Bi 0.4 Sb 1.592 Cd 0.008Te3, to obtain NiSbTe3 / p-type bismuth telluride layered powder, which was then sintered in N2 atmosphere, 50 MPa pressure and 693K temperature for 20 min to obtain a NiSbTe3 / p-type bismuth telluride sample with a NiSbTe3 barrier layer at one end. The NiSbTe3 / p-type bismuth telluride sample had a height of 5 mm and a diameter of 25 mm after leveling. (2) 1 g of NiSbTe3 powder with a particle size of 50±10 μm was placed in a graphite mold and flattened to obtain a NiSbTe3 layer. 28 g of n-type bismuth telluride-based region frit material with a diameter of 25 mm was placed on the NiSbTe3 layer and flattened. The specific composition of the n-type bismuth telluride-based region frit material is Bi2Te 2.65 Se 0.35 + 0.12wt% AgI to obtain NiSbTe3 / n-type bismuth telluride, which was then sintered for 10 min in an N2 atmosphere at a pressure of 100 MPa and a temperature of 713 K to obtain a NiSbTe3 / n-type bismuth telluride sample with a NiSbTe3 barrier layer at one end. The NiSbTe3 / n-type bismuth telluride sample had a height of 5 mm and a diameter of 25 mm after leveling. (3) respectively immersing the hot ends of the NiSbTe3 / p-type bismuth telluride sample in step (1) and the NiSbTe3 / n-type bismuth telluride sample in step (2) into melted low-temperature wax, so that the low-temperature wax solidifies on the surface of the hot end to form a protective layer; (4) At an ambient temperature of 303 K, the cold ends of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after completing step (3) are immersed in a mixed acid solution consisting of hydrochloric acid, nitric acid and water for 4 minutes, wherein the mass percentage of hydrochloric acid is 60%, the mass percentage of nitric acid is 85%, the volume ratio of 65% hydrochloric acid to 90% nitric acid in the mixed acid solution is 1:4, and the volume ratio of 65% hydrochloric acid to water is 1:6, and then ultrasonically cleaned in an ethanol solution to obtain the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after corrosion treatment; (5) Under the temperature condition of 315K, the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after the corrosion treatment in step (4) are immersed in an electroplating solution containing Ni(NH2SO3)2, NiCl·6H2O, H3BO3 and solvent as the cathode, and a single Ni plate is used as the anode. The electroplating treatment is carried out for 30 minutes. The concentration of Ni(NH2SO3)2 in the electroplating solution is 250 g / L, the concentration of NiCl·6H2O is 45 g / L, and the concentration of H3BO3 is 20 g / L, thereby obtaining NiSbTe3 / p-type bismuth telluride sample and NiSbTe3 / n-type bismuth telluride sample with a NiSbTe3 barrier layer at the hot end and a Ni barrier layer at the cold end; (6) The NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample that have completed step (5) are cut into thermoelectric arm particles by a dicing machine. The length and width of the thermoelectric arm particles are both 2.3 mm. Then, Cu-coated alumina ceramics are used as the upper substrate and the lower substrate respectively. The size of the upper substrate and the lower substrate are 20 mm×20 mm×0.3 mm. The upper substrate is the hot end, and 17 Cu electrodes with a size of 2.5 mm×2.5 mm×0.6 mm are attached. 92.5 Ag 2.5 The solder is connected to the NiSbTe3 barrier layer end, and the soldering temperature is 603 K; the lower substrate is the cold end, and 18 Cu electrodes with a size of 2.5 mm × 2.5 mm × 0.6 mm are attached. 42 Bi 58 The solder was connected to the Ni barrier layer at a soldering temperature of 423 K. The solder was kept at this temperature for 3 minutes and then transferred to a 303 K constant temperature water cooling plate to cool to room temperature. Copper wires were then soldered to lead out the electrodes to obtain a bismuth telluride-based thermoelectric device.

[0050] Example 3 This embodiment provides a bismuth telluride-based thermoelectric device, which is composed of a p / n-type bismuth telluride-based thermoelectric material, a barrier layer, a solder layer, a metal electrode, and a ceramic insulating circuit board, wherein the barrier layer is made of NiSbTe3; It is prepared by the following method: (1) 1 g of NiSbTe3 powder with a particle size of 50±10 μm was placed in a graphite mold and flattened to obtain a NiSbTe3 layer; 25 g of p-type bismuth telluride-based material powder with a particle size of 1000±300 nm was placed on the NiSbTe3 layer and flattened. The components of the p-type bismuth telluride-based material are Bi 0.4 Sb 1.592 Cd 0.008Te3, to obtain NiSbTe3 / p-type bismuth telluride layered powder, which was then sintered in N2 atmosphere, 100 MPa pressure and 693 K temperature for 3 min to obtain a NiSbTe3 / p-type bismuth telluride sample with a NiSbTe3 barrier layer on one end. The NiSbTe3 / p-type bismuth telluride sample had a height of 5 mm and a diameter of 25 mm after leveling. (2) 1 g of NiSbTe3 powder with a particle size of 50±10 μm was placed in a graphite mold and flattened to obtain a NiSbTe3 layer. 28 g of n-type bismuth telluride-based region frit material with a diameter of 25 mm was placed on the NiSbTe3 layer and flattened. The specific composition of the n-type bismuth telluride-based region frit material is Bi2Te 2.65 Se 0.35 + 0.12wt% AgI to obtain NiSbTe3 / n-type bismuth telluride, which was then sintered for 20 min in an N2 atmosphere at a pressure of 50 MPa and a temperature of 713 K to obtain a NiSbTe3 / n-type bismuth telluride sample with a NiSbTe3 barrier layer at one end. The NiSbTe3 / n-type bismuth telluride sample had a height of 5 mm and a diameter of 25 mm after leveling. (3) respectively immersing the hot ends of the NiSbTe3 / p-type bismuth telluride sample in step (1) and the NiSbTe3 / n-type bismuth telluride sample in step (2) into melted low-temperature wax, so that the low-temperature wax solidifies on the surface of the hot end to form a protective layer; (4) At an ambient temperature of 303 K, the cold ends of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after completing step (3) are immersed in a mixed acid solution consisting of hydrochloric acid, nitric acid and water for 4 minutes, wherein the mass percentage of hydrochloric acid is 70%, the mass percentage of nitric acid is 98%, the volume ratio of 65% hydrochloric acid to 90% nitric acid in the mixed acid solution is 1:3, and the volume ratio of 65% hydrochloric acid to water is 1:4, and then ultrasonically cleaned in an ethanol solution to obtain the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after corrosion treatment; (5) Under the temperature condition of 315 K, the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after the corrosion treatment in step (4) are immersed in an electroplating solution containing Ni(NH2SO3)2, NiCl·6H2O, H3BO3 and solvent as the cathode, and a single Ni plate is used as the anode. The electroplating treatment is carried out for 30 minutes. The concentration of Ni(NH2SO3)2 in the electroplating solution is 350 g / L, the concentration of NiCl·6H2O is 40 g / L, and the concentration of H3BO3 is 40 g / L, thereby obtaining NiSbTe3 / p-type bismuth telluride sample and NiSbTe3 / n-type bismuth telluride sample with a NiSbTe3 barrier layer at the hot end and a Ni barrier layer at the cold end; (6) The NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample that have completed step (5) are cut into thermoelectric arm particles by a dicing machine. The length and width of the thermoelectric arm particles are both 2.3 mm. Then, Cu-coated alumina ceramics are used as the upper substrate and the lower substrate respectively. The size of the upper substrate and the lower substrate are 20 mm×20 mm×0.3 mm. The upper substrate is the hot end, and 17 Cu electrodes with a size of 2.5 mm×2.5 mm×0.6 mm are attached. 92.5 Ag 2.5 The solder is connected to the NiSbTe3 barrier layer end, and the soldering temperature is 603 K; the lower substrate is the cold end, and 18 Cu electrodes with a size of 2.5 mm × 2.5 mm × 0.6 mm are attached. 42 Bi 58 The solder was connected to the Ni barrier layer at a soldering temperature of 423 K. The solder was kept at this temperature for 3 minutes and then transferred to a 303 K constant temperature water cooling plate to cool to room temperature. Copper wires were then soldered to lead out the electrodes to obtain a bismuth telluride-based thermoelectric device.

[0051] Test results description: Figure 1 This is a scanning electron micrograph of the NiSbTe3 / p-type bismuth telluride sample prepared in Example 1 after annealing, along with the corresponding line-scan elemental map. As can be seen, there is no significant reaction between the barrier layer and the material interface, and the material is well bonded. No cracks are present within the material, confirming its structural stability and excellent thermal stability.

[0052] Figure 2 The contact resistivity test data of the NiSbTe3 / p-type bismuth telluride sample prepared in Example 1 before and after continuous annealing at 523 K for 30 days is shown in the figure. As can be seen from the figure, the contact resistivity between the p-type bismuth telluride and the barrier layer is 3.7 μΩ cm 2 , and remains basically unchanged after annealing for 30 days, indicating that the NiSbTe3 barrier layer has good contact with the p-type bismuth telluride-based material and has good thermal stability.

[0053] Figure 3 The following figure compares the contact resistivity of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample prepared in Example 1 after annealing, and the contact resistance values ​​of samples using other materials as barrier layers. It can be seen that the barrier layer interface contact resistivity prepared in Example 1 is significantly better than that of other materials.

[0054] Figure 4 This chart compares the measured linear thermal expansion coefficients of NiSbTe3 alone, p-type bismuth telluride, and n-type bismuth telluride. The linear thermal expansion coefficient test is based on the widely used expansion rod method, which uses the change in length of the test object to calculate the thermal expansion coefficient. A solid rectangular specimen measuring 8 mm × 8 mm × 3 mm was used. When the ambient temperature varied from room temperature to 550 K, the length of the solid specimen changed due to thermal expansion. By measuring the length change and temperature change of the solid specimen, the linear thermal expansion coefficient (CTE) of the solid specimen material was calculated. The figure shows that across the full service temperature range of the bismuth telluride power generation device, the difference in CTE between the NiSbTe3 barrier material and the bismuth telluride-based thermoelectric material is within 20%, significantly superior to previously reported Ti barrier materials.

[0055] Figure 5 A comparison of shear and tensile strength test data for a NiSbTe3 barrier layer and a Ni barrier layer on a bismuth telluride substrate is shown. The shear strength test is based on the widely used single shear test, which measures shear strength by applying a shear force until the specimen breaks. The tensile strength test is based on a widely used tensile testing machine, which applies a tensile force at a constant rate until the specimen breaks. Before the specimen breaks, the tensile testing machine records the changes in tension and elongation, which can be used to calculate the tensile strength of the material. As shown in the figure, compared to the traditional electroplated Ni barrier layer, the shear and tensile strengths of the NiSbTe3 barrier layer are increased by more than five times, reaching 5 MPa and 10 MPa, respectively, demonstrating a strong and reliable mechanical structure.

[0056] Figure 6 This is a physical picture of the bismuth telluride-based thermoelectric device prepared in Example 1.

[0057] Figure 7 This figure shows the conversion efficiency data for the bismuth telluride-based thermoelectric device prepared in Example 1 after 100 cycles at hot-end temperatures of 540 K, 478 K, and 416 K. Each hot-end temperature point represents a single test, with each conversion efficiency point representing one test, for a total of 100 cycles. The figure shows that the efficiency of the bismuth telluride-based thermoelectric device remains relatively stable after 100 cycles.

[0058] Figure 8The following graph shows the output power and conversion efficiency data for the bismuth telluride-based thermoelectric device prepared in Example 1 after 15 days of service at a hot-end temperature of 540 K and a cold-end temperature of 285 K. As can be seen from the figure, the output power and conversion efficiency remain stable at 0.83 W and 6.8%, respectively, after 15 days of service, and neither decreases significantly with service time. This demonstrates that the bismuth telluride-based thermoelectric device prepared with a NiSbTe3 barrier layer has excellent device performance and exceptional thermal stability.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A barrier layer for a bismuth telluride-based thermoelectric device, characterized in that: The material of the barrier layer includes NiSbTe3.

2. A bismuth telluride-based thermoelectric device, characterized in that: A barrier layer as claimed in claim 1 is used.

3. A method for preparing a bismuth telluride-based thermoelectric device as claimed in claim 2, characterized in that: The following steps are involved: S1, NiSbTe3 material and p-type bismuth telluride-based material are sintered to form a NiSbTe3 barrier layer on the hot end surface of the p-type bismuth telluride-based material, thereby obtaining a NiSbTe3 / p-type bismuth telluride sample; S2, NiSbTe3 material and n-type bismuth telluride-based material are sintered to form a NiSbTe3 barrier layer on the hot end surface of the n-type bismuth telluride-based material, thereby obtaining a NiSbTe3 / n-type bismuth telluride sample; S3. A nickel barrier layer is plated on the cold end surface of the NiSbTe3 / p-type bismuth telluride sample described in step S1 and the cold end surface of the NiSbTe3 / n-type bismuth telluride sample described in step S2, and then the cold end surfaces are welded on a substrate after cutting to obtain a bismuth telluride-based thermoelectric device.

4. The method for preparing a bismuth telluride-based thermoelectric device according to claim 3, characterized in that: The sintering process in step S1 and step S2 is carried out under an atmosphere of N2, a pressure of 50-100 MPa, and a temperature of 673-723 K; And / or, the sintering time in step S1 is 3-20 min; And / or, the sintering time in step S2 is 10-20 min; And / or, the p-type bismuth telluride-based material is Bi co-doped with Ag, Cu, Cd, Mn, Mg, Ca and S. 0.4 Sb 1.6 Te3; And / or, the n-type bismuth telluride-based material is Bi2Te doped with one or two of BiCl3, AgI, SbI3, PbI2 and TeI4. 2.65 Se 0.35 .

5. The method for preparing a bismuth telluride-based thermoelectric device according to claim 3, characterized in that: The p-type bismuth telluride material is a modified Bi co-doped with Ag, Cu, Cd, Mn, Mg, Ca and Se. 0.5 Sb 1.5 Te3; And / or, the n-type bismuth telluride-based material is Bi2Te doped with one or two of BiCl3, AgI, SbI3, PbI2 and TeI4. 2.7 Se 0.3 ; And / or, the sintering process described in step S1 is to place NiSbTe3 powder in a graphite mold and flatten it to obtain a NiSbTe3 layer, place p-type bismuth telluride-based material powder on the NiSbTe3 layer and flatten it to obtain a NiSbTe3 / p-type bismuth telluride preform, and then sinter the NiSbTe3 / p-type bismuth telluride preform in a N2 atmosphere, a pressure of 50-100 MPa and a temperature of 673-723 K for 3-20 min; And / or, the sintering process described in step S2 is to place NiSbTe3 powder in a graphite mold and flatten it to obtain a NiSbTe3 layer, place an n-type bismuth telluride-based block on the NiSbTe3 layer and flatten it to obtain a NiSbTe3 / n-type bismuth telluride preform, and then sinter the NiSbTe3 / n-type bismuth telluride preform in a N2 atmosphere, a pressure of 50-100 MPa and a temperature of 673-723 K for 10-30 min; And / or, the process of plating the nickel barrier layer in step S3 includes wax protection, corrosion and electroplating.

6. The method for preparing a bismuth telluride-based thermoelectric device according to claim 5, characterized in that: The particle size distribution range of the NiSbTe3 powder is 10-100 μm; And / or, the particle size of the p-type bismuth telluride-based material powder is 200 nm-2 μm; And / or, the n-type bismuth telluride-based block is a bismuth telluride-based block with a diameter of 20-30 mm prepared by a zone melting method.

7. The method for preparing a bismuth telluride-based thermoelectric device according to claim 5, characterized in that: The wax immersion protection process is to immerse the hot ends of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample into melted low-temperature wax, and the low-temperature wax solidifies on the surface of the hot end to form a protective layer; And / or, the corrosion process is to immerse the cold ends of the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample in a mixed acid solution consisting of hydrochloric acid, nitric acid and water for 3-5 minutes, and then ultrasonically clean them in an ethanol solution to obtain the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after corrosion treatment; And / or, the electroplating process is to immerse the NiSbTe3 / p-type bismuth telluride sample and the NiSbTe3 / n-type bismuth telluride sample after corrosion treatment in an electroplating solution containing Ni(NH2SO3)2, NiCL·6H2O, H3BO3 and solvent as the cathode, and use a single Ni plate as the anode at a temperature of 313-318 K for electroplating for 20-40 min.

8. The method for preparing a bismuth telluride-based thermoelectric device according to claim 7, characterized in that: The mass percentage of the hydrochloric acid is 60-70% hydrochloric acid, and the mass percentage of the nitric acid is 85-98% nitric acid; And / or, in the mixed acid solution, the volume ratio of the hydrochloric acid to the nitric acid is 1:(3-4), and the volume ratio of the hydrochloric acid to the water is 1:(4-6); And / or, in the electroplating solution, the concentration of Ni(NH2SO3)2 is 250-350 g / L, the concentration of NiCL·6H2O is 15-40 g / L, and the concentration of H3BO3 is 20-40 g / L; And / or, the solvent in the electroplating solution is water.

9. The method for preparing a bismuth telluride-based thermoelectric device according to claim 3, characterized in that: The welding process in step S3 is to use Cu-coated alumina ceramic as the upper substrate and the lower substrate, the upper substrate is connected to the NiSbTe3 barrier layer through SnPbAg solder, and the lower substrate is connected to the nickel barrier layer through SnBi solder.

10. Application of the bismuth telluride-based thermoelectric device according to claim 2 in the field of thermoelectric conversion.

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