Preparation method of high-performance silver sulfide-based inorganic plastic thermoelectric composite material

Abstract

The invention belongs to the technical field of thermoelectric materials, and discloses a preparation method of a high-performance silver sulfide-based inorganic plastic thermoelectric composite material, which comprises the following steps: respectively weighing silver, sulfur, selenium and tellurium elementary substance powder according to the nominal chemical dosage ratio of Ag2S1 / 3Se1 / 3Te1 / 3, mixing to obtain mixed powder, and carrying out vacuum melting to obtain an Ag2S1 / 3Se1 / 3Te1 / 3 cast ingot; grinding the cast ingot to obtain Ag2S1 / 3Se1 / 3Te1 / 3 powder; and proportioning the Ag2S1 / 3Se1 / 3Te1 / 3 powder and the raw material constantan fiber, carrying out ball-milling mixing, and then carrying out spark plasma sintering to obtain the silver sulfide-based inorganic plastic thermoelectric material compounded with the constantan fiber. The preparation method is improved, the Ag2S1 / 3Se1 / 3Te1 / 3 matrix is formed through smelting, then the second-phase constantan alloy fiber is introduced through spark plasma sintering, the second-phase constantan alloy is dispersed and distributed in the matrix phase in the form of fiber, and the obtained composite material can effectively solve the problem that in the prior art, the power factor of an Ag2 (S, Se and Te) system material is low.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric materials technology, and more specifically, relates to a method for preparing a high-performance silver sulfide-based inorganic plastic thermoelectric composite material. Background Technology

[0002] To alleviate global environmental problems and the energy crisis, improving energy efficiency has become a key theme in global development. Thermoelectric materials can directly convert heat energy into electrical energy, recovering vast amounts of waste heat and converting it into high-quality electricity. Flexible thermoelectric materials and devices can generate electricity using relatively small temperature differences, utilizing not only industrial waste heat but also natural solar and human body heat as sustainable green energy sources. Currently, some emerging flexible thermoelectric materials, such as conductive polymers and low-dimensional semiconductors, exhibit low thermoelectric properties, making it difficult to produce devices with high output. Furthermore, the inherent brittleness of some cutting-edge inorganic thermoelectric materials results in poor flexibility in thermoelectric devices, becoming a major obstacle to their development. Therefore, developing thermoelectric materials that combine excellent thermoelectric properties with plasticity is crucial for advancing flexible thermoelectric technology.

[0003] Ag₂S is the first room-temperature ductile inorganic thermoelectric semiconductor discovered, opening new avenues for flexible thermoelectric energy conversion technology. To improve its thermoelectric performance, researchers have modified its inherent defects by doping it with Se or Te, thereby achieving high power factor and low thermal conductivity. The Ag₂S-Ag₂Se-Ag₂Te pseudo-ternary solid solution structure is particularly advantageous for forming highly symmetric phases (such as cubic phases). This highly symmetric crystal structure provides a multiple slip system, allowing the material to adopt more spatial orientations during slip, thus improving its ductility. However, the multi-component nature of the material makes composition control and performance optimization more complex and difficult. Currently, the average power factor of Ag₂(S, Se, Te) system materials is generally below 6 μW / cm². - ¹K - The value ² indicates that its output performance in thermoelectric devices is not yet ideal. Therefore, significantly improving its power factor without sacrificing its plasticity would be of great significance to the research and development of inorganic plastic thermoelectric materials. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a method for preparing high-performance silver sulfide-based inorganic plastic thermoelectric composite materials. This method improves the preparation process by first melting to form Ag₂S. 1 / 3Se 1 / 3 Te 1 / 3 The matrix is ​​then sintered with spark plasma to introduce second-phase constantan alloy fibers, which are then dispersed in the matrix phase Ag2S in the form of fibers.1 / 3 Se 1 / 3 Te 1 / 3 The resulting composite material can effectively solve the problem of low power factor in existing Ag2(S, Se, Te) system materials.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a silver sulfide-based inorganic plastic thermoelectric material is provided, characterized by comprising the following steps: (1) Under a protective atmosphere, according to Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 The nominal chemical dosage ratios of silver elemental powder, sulfur elemental powder, selenium elemental powder, and tellurium elemental powder were weighed out respectively. (2) Thoroughly mix the powders obtained in step (1) to obtain a mixed powder; (3) Place the mixed powder obtained in step (2) into a quartz tube and evacuate it to a pressure not exceeding 10. -5 After sealing, a vacuum-sealed quartz tube is obtained; (4) Melt the vacuum-sealed quartz tube obtained in step (3) to obtain Ag2S. 1 / 3 Se 1 / 3 Te 1 / 3 Ingot casting; (5) The Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 The ingot was ground to obtain Ag2S. 1 / 3 Se 1 / 3 Te 1 / 3 powder; (6) The Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 The powder and constantan fiber are mixed in a mass ratio of 1:x and then ball-milled in a planetary ball mill. The mixture is then subjected to discharge plasma sintering to obtain a silver sulfide-based inorganic plastic thermoelectric material composited with constantan fiber; wherein x does not exceed 30%.

[0006] As a further preferred embodiment of the present invention, in step (6), the sintering temperature of the discharge plasma sintering is 573-623K and the pressure is 40-50MPa; x is 10%-30%.

[0007] As a further preferred embodiment of the present invention, in step (4), the smelting is carried out at a smelting temperature of 1000℃-1100℃; Preferably, for the melting process, the heating time from room temperature to the melting temperature is 10-12 hours.

[0008] As a further preferred embodiment of the present invention, in step (5), the grinding is performed by first grinding the Ag2S... 1 / 3 Se 1 / 3 Te 1 / 3 After the ingot is cooled in liquid nitrogen, it is then ground and crushed in a mortar to obtain Ag₂S. 1 / 3 Se 1 / 3 Te 1 / 3 powder; Preferably, the Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 The particle size of the powder is 50-100 micrometers.

[0009] As a further preferred embodiment of the present invention, in step (6), the diameter of the raw material constantan fiber is 30-40 micrometers and the length is 1-2 millimeters.

[0010] As a further preferred embodiment of the present invention, in step (6), the ball milling speed used for ball milling is 300-500 rpm, and the ball milling time is 1-2 hours; Preferably, the ball milling is a wet ball milling; more preferably, the solvent used in the wet ball milling is alcohol.

[0011] As a further preferred embodiment of the present invention, in step (1), the protective atmosphere is argon.

[0012] According to another aspect of the present invention, the present invention provides a silver sulfide-based inorganic plastic thermoelectric material prepared by the above method.

[0013] According to another aspect of the present invention, the present invention provides the application of the above-mentioned silver sulfide-based inorganic plastic thermoelectric material as a thermoelectric material.

[0014] As a further preferred embodiment of the present invention, the application is for a human body thermoelectric energy harvesting device; Preferably, the human body thermoelectric energy harvesting device is a self-powered health monitoring patch or a flexible power generation wristband.

[0015] Compared with the prior art, the above technical solution conceived by this invention, due to the prior melting to form Ag2S, achieves a higher efficiency. 1 / 3Se 1 / 3 Te 1 / 3 The matrix is ​​then sintered with constantan alloy fibers as a second phase into Ag2S by discharge plasma sintering. 1 / 3 Se 1 / 3 Te 1 / 3In the matrix, the silver sulfide-based inorganic plastic thermoelectric material composited with constantan fibers effectively improves the electrical conductivity. While maintaining excellent plasticity, the power factor of this composite material is significantly improved. The silver sulfide-based inorganic plastic thermoelectric material composited with constantan fibers obtained using the method of this invention includes a matrix phase of Ag₂S. 1 / 3 Se 1 / 3 Te 1 / 3 The constantan alloy and the second phase are in a mass ratio of 1:x, and the second phase constantan alloy is distributed in the form of fibers in the Ag2S matrix. 1 / 3 Se 1 / 3Te 1 / 3 The silver sulfide-based inorganic plastic thermoelectric material with constantan fiber obtained by the method of this invention exhibits high performance, including a high power factor. Taking an embodiment of this invention as an example, the silver sulfide-based inorganic plastic thermoelectric composite material obtained by this invention has an average power factor of 9.2 μW / cm² at 300-700 K. -1 K -2 The highest power factor is 11.7 μWcm. -1 K -2 .

[0016] Specifically, the present invention can achieve the following beneficial effects: 1. Constantan alloys have good ductility. This invention introduces constantan fibers into the inorganic plastic thermoelectric material Ag2S. 1 / 3 Se 1 / 3 Te 1 / 3 In the process of maintaining the fiber morphology of constantan fiber in the second phase, a silver sulfide-based inorganic plastic thermoelectric composite material was obtained, which not only maintained excellent plasticity but also significantly improved its power factor.

[0017] 2. In the silver sulfide-based inorganic plastic thermoelectric composite material obtained in this invention, the second phase constantan alloy is dispersed in the matrix phase Ag2S in the form of fibers. 1 / 3 Se 1 / 3 Te 1 / 3 In this process, the composite material as a whole achieves a larger power factor. There are three main reasons for this: (1) Seebeck coefficient matching ensures no loss of electromotive force. Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 Both the matrix and constantan fibers exhibit similar Seebeck coefficients (approximately -40 μVK) at room temperature. -1(2) The construction of a fibrous high-conductivity continuous network significantly improves conductivity. Constantan fibers are uniformly penetrated and extended in the inorganic plastic matrix in a fiber morphology, which can form highly interconnected channels for rapid migration of charge carriers. The aspect ratio advantage of the fibers makes the threshold for the formation of conductive pathways significantly lower than that of the particulate second phase system, so that the overall resistance of the composite can be effectively reduced at a lower addition amount, and the conductivity can be significantly improved. (3) The fiber phase reinforcement structure maintains inorganic plasticity and stress synergistic dispersion. The constantan fiber embedding can share the stress with the plastic inorganic matrix, inhibit the brittle fracture propagation of the matrix, and help maintain the overall structural integrity and strain coordination ability of the material. The synergistic effect of this structure ensures that the composite material still has the inorganic plasticity characteristics of being compressible and machinable while ensuring the improvement of thermoelectric performance.

[0018] 3. The inorganic plastic thermoelectric composite material provided in this technical solution is composed of Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 The power factor of the final inorganic plastic thermoelectric composite material, made with constantan alloy, depends on the effect of different concentrations of constantan alloy on Ag₂S. 1 / 3 Se 1 / 3 Te 1 / 3 The material's role is that an excessive amount (mass fraction exceeding 30%) of the second phase leads to a shift in electrical transport from semiconductor-dominated to metal-dominated, resulting in a weaker thermoelectric output that is closer to metallic properties, thus causing the power factor to decrease instead of increase. Of course, with an addition ratio not exceeding 30%, the higher the addition percentage, the more significant the improvement in the material's power factor. In this invention, the constantan addition amount x can be preferably controlled at 10%-30%.

[0019] 4. The inorganic plastic thermoelectric composite material prepared based on this scheme is suitable for flexible and conformable thermoelectric energy harvesting devices for the human body. The material maintains stable thermoelectric properties during deformation, allowing for closer adhesion to the curved surface of the skin, thereby reducing interfacial thermal resistance, minimizing heat loss, and improving temperature difference utilization efficiency. For example, it can be further applied to wearable electronic systems such as self-powered health monitoring patches and flexible power generation wristbands. Furthermore, the material's excellent plasticity helps meet the processing requirements of devices in different geometries and complex working environments, making its application scenarios more diverse.

[0020] In summary, the synthesis method used in this invention is simple, the raw materials are relatively inexpensive and readily available, and the prepared composite material has both excellent plasticity and thermoelectric properties, and has broad application prospects in the field of flexible wearable thermoelectric devices. Attached Figure Description

[0021] Figure 1 This is a scanning electron microscope image of the product of Example 1 of the present invention.

[0022] Figure 2 The figures show the electrical conductivity of the products from Examples 1-3 and Comparative Example 1 as a function of temperature.

[0023] Figure 3 The curves show the Seebeck coefficient of the products of Examples 1-3 and Comparative Example 1 as a function of temperature.

[0024] Figure 4 The curves show the power factor of the products of Examples 1-3 and Comparative Example 1 as a function of temperature.

[0025] Figure 5 The image shows the compressive stress-strain curve of the product from Example 1.

[0026] Figure 6 The curve shows the change in conductivity of the product of Comparative Example 2 with temperature.

[0027] Figure 7 The curve shows the Seebeck coefficient of the product of Comparative Example 2 as a function of temperature.

[0028] Figure 8 The curve shows the power factor of the product of Comparative Example 2 as a function of temperature.

[0029] Figure 9 The curve shows the change in conductivity of the product of Comparative Example 3 with temperature.

[0030] Figure 10 The curve shows the Seebeck coefficient of the product of Comparative Example 3 as a function of temperature.

[0031] Figure 11 The curve shows the power factor of the product of Comparative Example 3 as a function of temperature. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0033] Example 1: A silver sulfide-based inorganic plastic thermoelectric composite material, comprising a matrix phase Ag₂S 1 / 3 Se 1 / 3 Te 1 / 3The mass ratio of the second-phase constantan alloy (grade 6J40) to the constantan alloy is 1:x, and in this embodiment, x is 30%. The second-phase constantan alloy is distributed in the form of fibers in the Ag2S matrix. 1 / 3 Se 1 / 3 Te 1 / 3 middle.

[0034] The preparation method of the above-mentioned silver sulfide-based inorganic plastic thermoelectric composite material includes the following steps: (1) Under a protective atmosphere (argon is used as the protective atmosphere in this embodiment; the same applies below), weigh out elemental silver, sulfur, selenium, and tellurium. The mass of each element is calculated according to the Ag₂S content. 1 / 3 Se 1 / 3 Te 1 / 3 Weigh the chemical formula. In this example, the amount of element Ag used is 2.9225g.

[0035] (2) Manually mix the initially weighed powder in a mortar for 30 minutes.

[0036] (3) Vacuum sealing. Place the thoroughly mixed powder into a quartz tube and evacuate to 10°C. -5 Seal after mounting.

[0037] (4) High-temperature smelting. The vacuum-sealed quartz tube is placed in a box furnace for high-temperature smelting. The smelting conditions are: slowly heating from room temperature to 1050℃ over 10 hours, holding at 1050℃ for 12 hours, and then cooling down with the furnace to obtain the smelted ingot.

[0038] (5) Ingot crushing. The ingot obtained by high-temperature melting is placed in liquid nitrogen for cooling, and then ground and crushed in a mortar to obtain powder with a particle size of 50-100 micrometers.

[0039] (6) Measure the Ag2S obtained in step (5) respectively. 1 / 3 Se 1 / 3 Te 1 / 3 3g of powder and 0.9g of constantan fiber with a diameter of 40 micrometers and a length of 1-2 mm were placed in a planetary ball mill for wet ball milling and mixing. The ball milling speed was 400 rpm and the time was 1.5 hours. The solvent used for wet ball milling was alcohol.

[0040] (7) After drying the powder mixed in step (6), it is subjected to discharge plasma sintering at a temperature of 573 K and a pressure of 40 MPa to obtain bulk Ag2S. 1 / 3 Se 1 / 3 Te 1 / 3 +30wt% Constantan inorganic plastic composite thermoelectric material (denoted as "Ag2S") 1 / 3 Se 1 / 3 Te 1 / 3(sample with +30wt% constantan).

[0041] Example 2: The only difference between this embodiment and Example 1 is that the amount of constantan fiber added in step (6) is 0.6g, i.e., x is 20%. All other steps and specific parameters are the same as in Example 1.

[0042] In this embodiment, Ag2S was obtained in bulk form. 1 / 3 Se 1 / 3 Te 1 / 3 +20wt% Constantan inorganic plastic composite thermoelectric material (denoted as "Ag2S") 1 / 3 Se 1 / 3 Te 1 / 3 (sample with +20wt% constantan).

[0043] Example 3: The only difference between this embodiment and Example 1 is that the amount of constantan fiber added in step (6) is 0.3g, i.e., x is 10%. All other steps and specific parameters are the same as in Example 1.

[0044] In this embodiment, Ag2S was obtained in bulk form. 1 / 3 Se 1 / 3 Te 1 / 3 +10wt% Constantan inorganic plastic composite thermoelectric material (denoted as "Ag2S") 1 / 3 Se 1 / 3 Te 1 / 3 (sample with +10wt% constantan).

[0045] Example 4: The only difference between this embodiment and Embodiment 1 is that the sintering temperature of the discharge plasma sintering in step (7) is 623K. All other steps and specific parameters are the same as in Embodiment 1.

[0046] Example 5: The only difference between this embodiment and Embodiment 1 is that the pressure of the discharge plasma sintering in step (7) is 50 MPa. All other steps and specific parameters are the same as in Embodiment 1.

[0047] Comparative Example 1: The difference between this comparative example and Example 1 is that no second phase constantan fiber was added, that is, the preparation was stopped after step (4) of Example 1.

[0048] The corresponding result obtained in this comparative example is Ag2S. 1 / 3 Se 1 / 3 Te 1 / 3 Pure phase (denoted as "Ag2S") 1 / 3 Se 1 / 3 Te 1 / 3"sample).

[0049] Comparative Example 2: This comparative example utilizes the eutectic method to prepare the silver sulfide-based inorganic plastic composite thermoelectric material Ag2S. 1 / 3 Se 1 / 3Te 1 / 3 +30wt% constantan, the preparation method includes the following steps: (1) Weigh out elemental silver, sulfur, selenium, and tellurium under a protective atmosphere. The mass of each element is determined according to the mass ratio of Ag₂S. 1 / 3 Se 1 / 3Te 1 / 3 Weigh the chemical formula. Then, weigh constantan fiber (the constantan fiber is the same as in the above example, using constantan fiber with a diameter of 40 micrometers and a length of 1-2 millimeters, grade 6J40) with a mass equivalent to 30% of the total mass of elements silver, sulfur, selenium, and tellurium. In this comparative example, the amount of element Ag used is 2.4116 g.

[0050] (2) Manually mix the initially weighed mixture in a mortar for 30 minutes.

[0051] (3) Vacuum sealing. Place the thoroughly mixed powder into a quartz tube and evacuate to 10°C. -5 Seal after mounting.

[0052] (4) High-temperature smelting. The vacuum-sealed quartz tube is placed in a box furnace for high-temperature smelting. The smelting conditions are: slowly heating from room temperature to 1050℃ over 10 hours, holding at 1050℃ for 12 hours, and then cooling to obtain the smelted ingot.

[0053] The comparative example yielded blocky Ag2S. 1 / 3 Se 1 / 3 Te 1 / 3 +30wt% constantan eutectic inorganic plastic composite thermoelectric material (denoted as "Ag2S") 1 / 3 Se 1 / 3 Te 1 / 3 "+30wt% Constantan (eutectic)" sample.

[0054] Comparative Example 3: The only difference between this comparative example and Example 1 is that the amount of constantan fiber added in step (6) is 1.2g, i.e., x is 40%. All other steps and specific parameters are the same as in Example 1.

[0055] The comparative example yielded blocky Ag2S. 1 / 3 Se 1 / 3 Te 1 / 3 +40wt% Constantan inorganic plastic composite thermoelectric material (denoted as "Ag2S") 1 / 3 Se 1 / 3Te 1 / 3 (sample with +40wt% constantan).

[0056] Performance characterization: The thermoelectric material sample prepared in Example 1 was examined using a scanning electron microscope, and the resulting image is shown below. Figure 1 As shown in the figure. It can be observed from the figure that constantan fibers in Ag2S... 1 / 3 Se 1 / 3 Te 1 / 3 The fibers exhibit a uniform and diffuse distribution within the matrix, possessing a high aspect ratio and penetrating or embedding themselves in the matrix along different directions, resulting in a relatively tight interfacial bond. This distribution morphology indicates that the constantan fibers form continuous or semi-continuous conduction paths composed of a highly conductive second phase within the composite material, which is beneficial for increasing the effective cross-sectional area of ​​the overall current-carrying channels, thereby significantly reducing resistivity. Furthermore, the fibrous second phase exhibits a randomly oriented three-dimensional network structure within the matrix, which can improve the bulk conductivity of the material without significantly deteriorating the intrinsic Seebeck coefficient of the matrix, thus achieving an overall improvement in the power factor. Simultaneously, the fiber morphology can suppress electron scattering to a certain extent, improving the carrier migration capability; the interface between the fibers and the matrix can also stabilize the microstructure without significantly affecting phonon transport, contributing to maintaining the mechanical stability of the material.

[0057] The conductivity (σ) of the products of Examples 1-3 and Comparative Example 1 as a function of temperature is shown in the following curves. Figure 2 As shown (the target temperatures used were 300K, 375K, 475K, 575K, and 675K, respectively). Overall, the electrical conductivity of this material system decreases with increasing temperature, exhibiting typical metal-like properties. This trend did not change after the addition of constantan. With the gradual increase in the amount of constantan fiber added, the electrical conductivity of the inorganic plastic thermoelectric composite material increased significantly, reaching 2079 Scm at room temperature (300K). -1 When increased to x=30%, 4525 Scm -1 This represents an increase of more than double.

[0058] The Seebeck coefficient (S) curves of the products of Examples 1-3 and Comparative Example 1 as a function of temperature are shown below. Figure 3The target temperatures used are 300K, 375K, 475K, 575K, and 675K, respectively. As shown in the figure, the absolute value of the Seebeck coefficient of this material system increases with increasing temperature. With the gradual increase in the amount of constantan fiber added, the Seebeck coefficient of the inorganic plastic thermoelectric composite material shows a slight decreasing trend. After the introduction of constantan fiber, the overall energy filtering effect and carrier transport directionality of the composite system do not change significantly, and the macroscopic Seebeck coefficient of the system remains at a relatively stable level. With the increase of constantan content, more high-speed carrier channels composed of high-conductivity constantan fibers are formed inside the composite material, causing a redistribution of the equivalent carrier transport path: carriers tend to transport preferentially along the constantan phase. Since the Seebeck coefficient of constantan is slightly lower than that of the matrix material, its contribution weight increases with increasing content, thus the equivalent Seebeck coefficient of the composite material shows a slight decreasing trend. However, because the Seebeck coefficients of the two phases are very close, and the interface scattering does not produce a significant energy filtering effect, the overall Seebeck coefficient variation is limited.

[0059] The power factor (PF) curves of the products of Examples 1-3 and Comparative Example 1 as a function of temperature are shown below. Figure 4 As shown (the target temperature conditions used were 300K, 375K, 475K, 575K, and 675K), the average power factor corresponding to the 300-700K range was obtained by integrating the area of ​​the fitted curve. Thanks to the significantly improved conductivity after adding constantan fiber, this inorganic plastic thermoelectric composite material ultimately achieved a power factor of 9.2 μW / cm² in the temperature range of 300-700K at x=30%. - ¹K - The average power factor is 11.7 μW / cm². - ¹K - The highest power factor is 2 at 570K.

[0060] Ag2S synthesized in Example 1 1 / 3 Se 1 / 3 Te 1 / 3 The compressive stress-strain curve of the +30wt% constantan inorganic plastic composite thermoelectric material is shown below. Figure 5 As shown, the material exhibits the characteristics of a highly ductile material, with a compressive strain exceeding 50%, no fracture occurring within the test range, and the curve tending to be smooth and flat. It can be compressed from a cubic prism into a flat cylinder, indicating that the inorganic ductile composite thermoelectric material synthesized by this preparation method has extremely high ductility, which is beneficial for practical applications.

[0061] Ag2S synthesized in Examples 4 and 5 1 / 3 Se 1 / 3 Te 1 / 3The conductivity, Seebeck coefficient, and other properties of the +30wt% constantan inorganic plastic composite thermoelectric material are basically the same as those of the product in Example 1. Therefore, the temperature and pressure of discharge plasma sintering can be selected within the range of 573-623K and 40-50MPa without significantly affecting the product performance.

[0062] The conductivity, Seebeck coefficient, and power factor of the product of Comparative Example 2 as a function of temperature are shown in the figure below. Figures 6-8 The target temperatures used were 300K, 375K, 475K, 575K, and 675K, respectively. As shown in the figure, the trends of conductivity and Seebeck coefficient with temperature are similar to those in Example 1, but the improvement in conductivity is significantly weaker. This may be because during high-temperature eutectic melting, strong interdiffusion and chemical reactions occur between constantan and the matrix, causing metal elements to enter the matrix and form new solid solutions or second phases, thereby altering the carrier concentration and band structure of the matrix. Simultaneously, high-temperature treatment easily damages the morphology of the metal phase, making it impossible to form efficient and continuous conductive pathways. Ultimately, this results in a lower power factor performance compared to Example 1.

[0063] The conductivity, Seebeck coefficient, and power factor of the product in Comparative Example 3 as a function of temperature are shown in the following figures. Figures 9-11 As shown in the figure (the target temperature conditions used were 300K, 375K, 475K, 575K, and 675K, respectively). As can be seen from the figure, although the conductivity of the product of Comparative Example 3 was still improved compared with Examples 1 to 3, the improvement was limited, resulting in a decrease in the power factor instead of an increase (this may be because excessive constantan fiber causes the electrical transport to shift from semiconductor-dominated to metal-dominated, and the material as a whole exhibits a weak thermoelectric output that is closer to that of metal, thus leading to a decrease in the power factor instead of an increase).

[0064] The above embodiments are merely examples. For instance, in addition to argon, the protective atmosphere can also be N2 or other inert gases; and for example, after melting, in addition to furnace cooling, temperature-controlled cooling (cooling time can be controlled for 8-12 hours) or natural cooling can also be used.

[0065] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing a silver sulfide-based inorganic plastic thermoelectric material, characterized by, The method comprises the following steps: (1) In the protective atmosphere environment, the nominal chemical dose ratio of silver, sulfur, selenium and tellurium is respectively taken as the basis to weigh the elemental silver powder, elemental sulfur powder, elemental selenium powder and elemental tellurium powder; 1 / 3 Se 1 / 3 Te 1 / 3 ​ (2) mixing the powders obtained in step (1) to obtain a mixed powder; (3) The mixed powder obtained in step (2) is placed in a quartz tube, vacuumed to a pressure of not more than 10 -5 The quartz tube is sealed by a back seal to obtain a vacuum-sealed quartz tube; (4) The vacuum-sealed quartz tube obtained in step (3) is subjected to smelting to obtain Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 ingot (5) The Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 The ingot was ground to obtain Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 powder; (6) the Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 The powder and raw constantan fiber are mixed in a planetary ball mill at a mass ratio of 1 :x, and then the mixture is sintered by spark plasma sintering, so as to obtain the silver sulfide-based inorganic plastic thermoelectric material with the constantan fiber compounded; wherein x is not more than 30%.

2. The preparation method according to claim 1, characterized in that, In step (6), the sintering temperature of the spark plasma sintering is 573-623 K, and the pressure is 40-50 MPa; x is 10%-30%.

3. The preparation method according to claim 1, characterized in that, In step (4), the smelting is performed at a smelting temperature of 1000-1100 °C. Preferably, for the smelting, the temperature rising time for rising the temperature from room temperature to the smelting temperature is 10-12 hours.

4. The preparation method according to claim 1, characterized in that, In step (5), the grinding is first grinding the Ag2S 1 / 3Se 1 / 3 Te 1 / 3 The ingot is cooled in liquid nitrogen and then ground in a mortar to obtain Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 powder; Preferably, the Ag2S 1 / 3 Se 1 / 3 Te 1 / 3 The particle size of the powder is 50-100 microns.

5. The method of claim 1, wherein the step of forming the first and second layers is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (6), the diameter of the raw material constantan fiber is 30-40 microns, and the length is 1-2 millimeters.

6. The method of claim 1, wherein the step of forming the first and second layers is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step (6), the ball milling speed for the ball milling mixing is 300-500 rpm, and the ball milling time is 1-2 hours. Preferably, the ball milling mixing is wet ball milling; more preferably, the solvent used in the wet ball milling is alcohol.

7. The preparation method according to claim 1, characterized in that, In step (1), the protective atmosphere is argon.

8. A silver sulfide-based inorganic plastic thermoelectric material prepared by the method according to any one of claims 1-7.

9. Use of the silver sulfide-based inorganic plastic thermoelectric material according to claim 8 as a thermoelectric material.

10. The use according to claim 9, wherein the compound is ###0006### The use is for a human body thermoelectric energy collection device. Preferably, the human body thermoelectric energy collection device is a self-powered health monitoring patch or a flexible power generation wristband.

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