Cu-doped PbTe-based thermoelectric material and preparation method thereof

Abstract

The application discloses a Cu-doped PbTe-based thermoelectric material and a preparation method thereof. The Cu-doped PbTe-based thermoelectric material is carbon-coated high-entropy second phase composite Cu-doped n-type PbTe; wherein the high-entropy second phase is Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 ; and the composite mass ratio of the high-entropy second phase is 1% to 10%. The preparation method is based on vacuum melting, ball milling coating and rapid hot-pressing sintering, is mature and controllable, is suitable for large-scale preparation of bulk materials, and ensures stability of thermoelectric performance and microstructure.

Description

Technical Field

[0001] This application relates to the field of thermoelectric materials technology, specifically to a Cu-doped PbTe-based thermoelectric material and its preparation method. Background Technology

[0002] In recent years, thermoelectric technology has received widespread attention in the field of energy utilization, with applications such as waste heat recovery from automobiles, thermoelectric refrigeration, flexible electronic sensors, and localized cooling for integrated circuits. Among these, industrial waste heat recovery is a major application area. The waste heat generated in industrial processes is generally at a temperature of 500-900 K, and the development of mid-temperature thermoelectric materials is of great significance for sustainable energy development.

[0003] PbTe-based thermoelectric materials are representative materials in the mid-temperature range and have been applied to core components of thermoelectric generators used in NASA's deep space exploration. The significant energy difference between the heavy and light bands in the electronic structure of n-type PbTe means that electron transport relies primarily on a single energy band, limiting the potential for improving its electron transport performance through band degeneracy. Therefore, research on improving the thermoelectric performance of n-type PbTe mainly focuses on optimizing carrier concentration and reducing lattice thermal conductivity.

[0004] Dynamic doping is currently a relatively mature method for carrier manipulation in this field. Studies have shown that small atomic radius metal elements with temperature-sensitive properties, such as Cu, Ag, and Mn, can diffuse into the intercrystalline interstitial spaces during heating, releasing carriers and thus improving carrier concentration and power factor. However, dynamic doping mainly improves the power factor by regulating electron transport, with limited effect on reducing lattice thermal conductivity; furthermore, because its effect is temperature-dependent, the thermal properties of the material may fluctuate over a wide temperature range. Therefore, its application remains limited by the doping amount and temperature control.

[0005] Reducing lattice thermal conductivity is typically achieved by constructing multi-scale structures, i.e., introducing defects or second phases ranging from atomic to micrometer scales into the material to achieve phonon scattering across the entire frequency range, thereby reducing thermal conductivity without significantly affecting electrical properties. Endogenous modulation doping can induce the spontaneous precipitation of nanoscale second phases, but the particle size and content are difficult to control precisely, and they tend to grow during molding or annealing. External nanocomposites are created by incorporating pre-fabricated nanoparticles into the material, and carbon coating can be used to suppress particle growth, but the preparation process is complex, with low yield and high cost, limiting large-scale applications. Summary of the Invention

[0006] To address the aforementioned deficiencies in this field, this application aims to provide a Cu-doped PbTe-based thermoelectric material and its preparation method.

[0007] According to one aspect of this application, a Cu-doped PbTe-based thermoelectric material is provided, comprising carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe; Among them, the high-entropy second phase is Cu. 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 ; The composite mass ratio of the high-entropy second phase is 1%-10%.

[0008] According to some embodiments of this application, the doping atomic ratio of Cu is 0.05-0.25 at.

[0009] According to some embodiments of this application, the doping ratio of Cu is 0.15 at.

[0010] According to some embodiments of this application, the composite mass ratio of the high-entropy second phase is 7%.

[0011] According to another aspect of this application, a method for preparing the above-mentioned Cu-doped PbTe-based thermoelectric material is provided, comprising: 0.05-0.25 at% Cu-PbTe powder was prepared by vacuum melting method; Cu was prepared by vacuum melting method 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 powder; Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 The powder reacts with dopamine hydrochloride to prepare Cu 0.004 Pb 0.99 Sn 0.0 1Se 0.5 Te 0.25 S 0.25 @PDA powder; Mix 0.05-0.25 at% Cu-PbTe powder with Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder was mixed and then annealed to obtain carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe powder.

[0012] According to some embodiments of this application, Cu 0.004 Pb 0.99 Sn 0.01Se 0.5 Te 0.25 S 0.25 Before the powder reacts with dopamine hydrochloride, the process also includes: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 The powder is ball-milled.

[0013] According to some embodiments of this application, Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 The powder reacts with dopamine hydrochloride to prepare Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder, including: Cu ball-milled powder 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 The powder was dispersed in deionized water, mixed and stirred with an equal mass of dopamine hydrochloride, and then a triaminomethane solution was added to react.

[0014] According to some embodiments of this application, 0.05-0.25 at% Cu-PbTe powder is mixed with Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder is mixed and then annealed, including: mixing 0.05-0.25 at% Cu-PbTe powder with Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder is mixed in anhydrous ethanol and then dried to obtain a mixed powder; The mixed powder was annealed at 280-320 °C for 2.5-4.0 h in a hydrogen-argon mixed atmosphere.

[0015] According to some embodiments of this application, the preparation method further includes: hot pressing carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe powder to obtain carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe bulk material.

[0016] According to some embodiments of this application, the hot pressing process includes: hot pressing at a constant temperature of 500-600 °C for 10 min under vacuum conditions with an axial pressure of 45-55 MPa and a pressure of less than 10 Pa.

[0017] According to some embodiments of this application, the heating rate of the hot pressing process is 80-120°C / minute.

[0018] According to some embodiments of this application, 0.15 at% Cu-PbTe powder was prepared by vacuum melting. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the preparation process of Cu-doped PbTe-based thermoelectric materials in an example embodiment of this application.

[0020] Figure 2 The electrical transport properties of the thermoelectric material sample y at% Cu-PbTe (y=0, 0.05, 0.15, 0.25) as a function of temperature in the example embodiment of this application are shown in the graphs: (a) conductivity; (b) Seebeck coefficient; (c) power factor.

[0021] Figure 3 The thermal transport properties of the thermoelectric material sample y at% Cu-PbTe (y=0, 0.15, 0.25) as a function of temperature in the example embodiment of this application are shown in the following graphs: (a) total thermal conductivity; (b) electronic thermal conductivity; (c) lattice thermal conductivity.

[0022] Figure 4 ZT values ​​of the thermoelectric material sample y at% Cu-PbTe (y=0, 0.15, 0.25) as a function of temperature in an example embodiment of this application.

[0023] Figure 5 This is a grain diagram of the thermoelectric material before and after composite processing in an example embodiment of this application.

[0024] Figure 6 This is a diagram showing the dislocation distribution before and after the thermoelectric material is combined in an example embodiment of this application.

[0025] Figure 7 The electrical performance test data of the thermoelectric materials in the example embodiments of this application are provided.

[0026] Figure 8 The thermal performance test data of the thermoelectric materials in the example embodiments of this application are provided.

[0027] Figure 9 The thermoelectric figure of merit (ZT) test data of the thermoelectric materials in the example embodiments of this application. Detailed Implementation

[0028] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] It should be particularly noted that similar substitutions and modifications made to this application are obvious to those skilled in the art, and they are all considered to be included in this application. Those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this application to implement and apply the technology of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0030] Unless otherwise specified, this application is conducted under standard conditions or conditions recommended by the manufacturer. The raw materials or excipients used, as well as the reagents or instruments used, whose manufacturers are not specified, are all conventional products that can be obtained commercially.

[0031] The following is a detailed description of this application.

[0032] This application aims to improve the overall thermoelectric performance and microstructural stability of n-type PbTe-based thermoelectric materials prepared by existing processes. Currently, n-type PbTe-based thermoelectric materials still face several technical limitations in mid-temperature applications. First, the conduction band of n-type PbTe consists of a heavy band and a light band with a large energy difference, meaning electron transport mainly relies on a single band, limiting the improvement of the power factor. Second, although small atomic radius metals such as Cu can improve the power factor by optimizing carrier concentration through dynamic doping, their effect on reducing lattice thermal conductivity is limited and temperature-dependent, potentially leading to fluctuations in thermal performance over a wide temperature range. Traditional endogenous or exogenous nanocomposite methods can introduce a second phase to reduce lattice thermal conductivity, but precise control over particle size, distribution, and content is difficult, and the preparation process is complex and costly, hindering large-scale industrial production.

[0033] This application utilizes a Cu dynamic doping and carbon-coated high-entropy second-phase composite strategy to effectively optimize carrier concentration, reduce lattice thermal conductivity, and suppress grain growth and interface degradation, thereby improving the thermoelectric performance and microstructure stability of the material over a wide temperature range. Furthermore, this method is suitable for large-scale fabrication and engineering applications.

[0034] The technical solution of this application includes at least one of the following beneficial effects: Achieving synergistic optimization of Cu dynamic doping and high-entropy second phase: By dynamically diffusing Cu elements to release charge carriers during the heating process, high-entropy second phase particles provide multi-scale interface scattering, and lattice distortion enhances phonon scattering, thus simultaneously optimizing charge carrier concentration and lattice thermal conductivity. This mechanism increases the material's peak ZT value to 1.38 and the average ZT value from 0.58 to 1.01.

[0035] Significantly reduces lattice thermal conductivity and inhibits grain growth: High-entropy second-phase particles generate a Zener pinning effect on grain boundaries, and the carbon coating layer prevents particle agglomeration and growth. The average grain size is reduced from 55.77 μm to about 8.51 μm, and the lattice thermal conductivity can be reduced to as low as 0.39 W / m / K.

[0036] Excellent performance over a wide temperature range: Cu dynamic doping provides temperature-dependent carrier regulation, and the high-entropy second phase and carbon-coated interface ensure that the electrical conductivity remains at a high level from room temperature to 850 K, while effectively maintaining the Seebeck coefficient. At the same time, the lattice thermal conductivity is below 1 W / m / K across the entire temperature range, enabling the material to achieve good thermoelectric performance over a wide temperature range.

[0037] Suitable for large-scale preparation and engineering applications: The preparation method is based on vacuum melting, ball milling coating and rapid hot pressing sintering. The process is mature and controllable, suitable for the large-scale preparation of bulk materials, while ensuring thermoelectric performance and microstructure stability.

[0038] In some examples, such as Figure 1 As shown, the preparation method of the Cu-doped PbTe-based thermoelectric material of this application includes: Step S110: Raw material preparation: Weigh 0.05 at% - 0.25 at% Cu-PbTe according to atomic ratio; Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 Weigh according to atomic ratio: Cu foil, Pb particles (1~3 mm), Te particles (1~10 mm), Sn particles (1~3 mm), Se particles (1~6 mm), S powder.

[0039] Steps S120-S130: Prepare 0.05 at%-0.25 at% Cu-PbTe and high-entropy Cu, respectively. 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 Powder: Place the weighed raw materials into clean, dry quartz test tubes (φ=15 mm), and evacuate to a vacuum level below 5×10⁻⁶. -3After Pa, the test tube was sealed. To prevent the test tube from breaking during melt annealing, it was placed in a test tube with a slightly larger inner diameter (φ=20 mm) for secondary vacuum sealing. The sealed test tube was then placed in a muffle furnace and heated from room temperature to 1100 °C at a rate of 2.5 °C / min, held for 12 h, and then rapidly cooled by water quenching. After cooling, the quartz tube was placed back in the muffle furnace, heated to 600 °C, held for 48 h, and finally allowed to cool naturally to room temperature. The test tube was broken to remove the ingot, which was then ground into powder using an agate mortar and pestle to obtain the initial powder samples for each series.

[0040] Step S140: Preparation of Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder: The above Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 The powder was placed in a planetary ball mill and wet-milled at a speed of 500 rpm for 6 hours. Anhydrous ethanol was used as the grinding medium, with the following ratio: 20 g grinding balls: 50 mL ethanol: 1 g powder. After drying, a certain amount of the high-entropy powder after ball milling was dispersed in deionized water and stirred for 30 min. An equal mass of dopamine hydrochloride was added and stirred for another 30 min. Then, a buffer solution of triaminomethane was added, and the reaction was carried out for 4 hours. After washing several times with deionized water and anhydrous ethanol, the sample was dried in a vacuum drying oven at 60 ℃ to obtain a sample with polydopamine-coated surface—Cu. 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder.

[0041] Step S150: Preparation of carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe powder: The prepared 0.05at%-0.25at% Cu-PbTe powder is mixed with Cu... 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25@PDA was mechanically stirred in anhydrous ethanol at a mass ratio of 100%:(1-10)% for 24 h. After filtration, the solid was placed in a vacuum drying oven at 60 ℃ and dried for 24 h. Then, the mixed powder was placed in a tube furnace and annealed at 300 ℃ for 3 h under a hydrogen-argon mixed atmosphere. At this temperature, the PDA coating layer will carbonize to form carbon coating, thus obtaining carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe powder.

[0042] Step S160: Preparation of carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe bulk: Carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe powder is filled into a graphite mold with a diameter of φ12.5 mm or 14 mm × 14 mm. The bulk sample is obtained by using a rapid hot press furnace (FHP-828, Suzhou Haten Technology Co., Ltd., Suzhou, China) under an axial pressure of 50 MPa and a vacuum condition of less than 10 Pa, and is kept at 550 ℃ for 10 min (heating rate: 100 ℃ / min).

[0043] Example 1 The samples are denoted as y at% Cu-PbTe (y = 0, 0.05, 0.15, 0.25), and the relevant electrical properties are as follows: Figure 2 As shown. From Figure 2 (a) and Figure 2 (b) It can be observed that with the increase of Cu doping concentration, the conductivity of the sample shows a significant increasing trend, while the Seebeck coefficient shows a corresponding decrease. This typical electrical complementary behavior reflects the effective regulation of carrier concentration. This is attributed to the tendency of Cu atoms to occupy interstitial sites in the PbTe lattice, contributing additional electrons as donor impurities, thereby significantly increasing the carrier concentration of the system. Comprehensive analysis of electrical transport parameters shows that when the Cu doping concentration is 0.25 at%, the power factor of the material reaches its peak, approximately 29.15 μW / cm / K. 2 ,like Figure 2 As shown in (c), the average power factor of each sample is shown in Table 1 below.

[0044] Table 1

[0045] according to Figure 2 Based on the data results in Table 1, this application further selected samples (y = 0, 0.15, 0.25) for thermal conductivity testing, and the test results are as follows. Figure 8 As shown in the figure. The results show that, in the low-temperature range, the samples doped with 0.15 at% Cu and 0.25 at% Cu exhibit a lower overall thermal conductivity (κ). tot The phenomenon that is slightly higher than that of the undoped matrix ( Figure 3 (a)). Through formula κ L=κ tot κ e The calculated lattice thermal conductivity as a function of temperature is shown in Figure 3(c). As can be seen from the figure, the lattice thermal conductivity of the Cu-doped material exhibits a significant decrease. This is mainly due to two reasons: firstly, Cu atoms entering the PbTe lattice, whether replacing Pb sites or occupying interstitial positions, can act as point defects, enhancing the scattering of phonons; secondly, at high temperatures, Cu atoms in interstitial positions exhibit "liquid-like" behavior, generating additional phonon scattering as moving atoms or ions, thus significantly suppressing lattice thermal transport and achieving effective control over the overall thermal transport properties of the material.

[0046] Based on the comprehensive test results of the above-mentioned electrical transport and thermal properties, this application calculated and evaluated the ZT values ​​of all prepared samples within the test temperature range (300-800 K). The results are as follows: Figure 4 As shown in the figure, experimental data demonstrate that Cu doping effectively enhances the thermoelectric properties of the PbTe matrix. The introduction of Cu atoms into the PbTe lattice not only increases the carrier concentration and significantly enhances electrical conductivity, but also increases phonon scattering centers and reduces lattice thermal conductivity, ultimately leading to improved thermoelectric performance. Among all tested samples, the sample with Cu doping at y = 0.15 exhibits the best thermoelectric performance, achieving a maximum ZT value of 1.12 at 786 K, representing a significant performance improvement compared to the undoped PbTe matrix.

[0047] Example 2 The thermoelectric materials of this application were prepared according to the above preparation method.

[0048] Among them, 0.15at% Cu-PbTe and Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA quality ratio includes: 100%: 1% (sample abbreviation: 0.15 at% Cu-PbTe + 1% HE2P) 100%: 4% (sample abbreviation: 0.15 at% Cu-PbTe + 4% HE2P) 100%: 7% (sample abbreviation: 0.15 at% Cu-PbTe + 7% HE2P) 100%:10% (sample abbreviation: 0.15 at% Cu-PbTe + 10% HE2P) Test case The performance of the carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe bulk material prepared in the above embodiments was tested.

[0049] 1. Grain size distribution Test results are as follows Figure 5 As shown, where Figure 5 (ae) represents the inverse pole figure orientation map and grain boundary distribution map (IPF+GB) of each sample. Figure 5 (f) shows the corresponding statistical results for the average grain size. From Figure 5 As can be seen in (a), the sample without HE2P composite (x = 0%) exhibits a distinct coarse grain structure with an average grain size of up to 55.77 μm. Figure 5 (b) and Figure 5 (c) The test results of the composite 1% and 4% HE2P samples are respectively. As the HE2P content increases, the grain size decreases significantly. The finest grain structure is reached when x = 4%, and the average grain size decreases to 4.34 μm. Figure 5 (d) and Figure 5 (e) shows the test results for the composite 7% and 10% HE2P samples, with average grain sizes of approximately 8.51 μm and 8.09 μm, respectively, which are somewhat higher than those of the 4% HE2P sample. Figure 5 (f) shows the statistical results of the average grain size of the corresponding samples. The results indicate that the introduction of high-entropy second-phase particles in this application can effectively suppress matrix grain growth and achieve significant grain refinement. This is mainly because the high-entropy second-phase particles have a pinning effect on grain boundary migration, thereby limiting the grain coarsening process; however, when the HE2P content is too high, the second-phase particles may coarsen or locally agglomerate, thus weakening their inhibitory effect on grain boundary migration.

[0050] 2. Dislocation distribution Test results are as follows Figure 6 As shown, Figure 6 (a) Figure 6 (b) The geometrically required dislocation (GND) distribution diagrams of the sample without HE2P and the sample of this application with 0.15 at% Cu-PbTe + 7% HE2P, respectively. The comparison shows that after introducing 7% HE2P into 0.15 at% Cu-PbTe, the density of geometrically required dislocations inside the material increases significantly, and a wider range of micro-distortion and dislocation enrichment regions are formed at grain boundaries and heterojunctions. These features provide abundant phonon scattering centers, which helps to reduce lattice thermal conductivity and improve electrical transport properties.

[0051] 3. Electrical performance testing Test results are as follows Figure 7 As shown, where, Figure 7(a) shows the relationship between the conductivity of each sample and temperature. It can be seen that all composite samples show similar trends. Compared with the uncomposite samples, the overall conductivity of the material decreased after being composited with HE2P. This is because the high-entropy second-phase particles introduce more interface and defect scattering, thereby increasing the obstruction of carrier transport. Figure 7 (b) shows the Seebeck coefficient as a function of temperature. The absolute value of the composite sample is slightly higher than that of the uncomposite sample in the low temperature region. The change is stable as the temperature increases, indicating that the high-entropy second phase particles may have a slight effect on the carrier energy distribution, and the carrier transport remains stable. Figure 7 (c) shows the power factor as a function of temperature. The results indicate that the HE2P composite sample still maintains a high power factor, with the 1% HE2P sample exhibiting a superior power factor over a wider temperature range. These results demonstrate that the introduction of a high-entropy second phase in this application improves the electrical transport properties of the material to some extent while maintaining relative microstructural stability.

[0052] 4. Thermal performance testing Test results are as follows Figure 8 As shown, where, Figure 8 (a) shows the relationship between total thermal conductivity and temperature. It can be seen that the total thermal conductivity of the composite HE2P sample is significantly lower than that of the pure PbTe sample. In particular, the 7% and 10% HE2P samples show low thermal conductivity throughout the entire test temperature range. Figure 8 (b) shows the relationship between electronic thermal conductivity and temperature, and its trend is basically consistent with that of electrical conductivity. Figure 8 (c) shows the relationship between lattice thermal conductivity and temperature. It can be seen that the lattice thermal conductivity decreases significantly after incorporating 7% and 10% HE2P, remaining below 1 W / m / K throughout the entire temperature range. The 10% HE2P sample achieves the lowest lattice thermal conductivity of 0.30 W / m / K near approximately 573 K. The results indicate that the introduction of a high-entropy second phase in this application forms a large number of point defects, grain boundaries, dislocations, and heterojunctions within the material. These structures effectively enhance phonon scattering, thereby significantly suppressing lattice thermal transport and reducing the material's thermal conductivity.

[0053] 5. Thermoelectric figure of merit Test results are as follows Figure 9The figure shows the relationship between the ZT values ​​of each sample and temperature. Compared with the pure PbTe sample, the ZT values ​​of the samples with HE2P composite were significantly improved. Among them, the 7% HE2P sample showed the highest ZT value in the high-temperature region, reaching approximately 1.38 at about 823 K. The results indicate that after introducing a high-entropy second phase, the lattice thermal conductivity was effectively reduced through the synergistic effect of grain boundaries, dislocations, and heterostructures, while maintaining good electrical transport properties, thus achieving a significant improvement in thermoelectric performance. When the HE2P content was further increased to 10%, the ZT value decreased to some extent due to the significant decline in electrical transport properties. Overall, this application effectively optimized the comprehensive thermoelectric performance of the material by introducing an appropriate amount of high-entropy second phase.

[0054] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A Cu-doped PbTe-based thermoelectric material, characterized in that, This includes carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe; The high-entropy second phase is Cu. 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 ; The composite mass ratio of the high-entropy second phase is 1%-10%; The doping atomic ratio of Cu is 0.05-0.25 at.

2. The Cu-doped PbTe-based thermoelectric material according to claim 1, characterized in that, The composite mass ratio of the high-entropy second phase is 7%.

3. A method for preparing a Cu-doped PbTe-based thermoelectric material as described in claim 1 or 2, characterized in that, include: 0.05-0.25 at% Cu-PbTe powder was prepared by vacuum melting method; Cu was prepared by vacuum melting method 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 powder; The Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 The powder reacts with dopamine hydrochloride to prepare Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder; The 0.05-0.25 at% Cu-PbTe powder was mixed with the Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder was mixed and then annealed to obtain carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe powder.

4. The preparation method according to claim 3, characterized in that, In the Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.2 5S 0.25 Before the powder reacts with dopamine hydrochloride, the process further includes: [the process involves] reacting the Cu... 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 The powder is ball-milled.

5. The preparation method according to claim 4, characterized in that, The Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.2 5S 0.25 The powder reacts with dopamine hydrochloride to prepare Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder, including: Cu after ball milling 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 The powder was dispersed in deionized water, mixed and stirred with an equal mass of dopamine hydrochloride, and then a triaminomethane solution was added to react.

6. The preparation method according to claim 3, characterized in that, The 0.05-0.25 at% Cu-PbTe powder was mixed with the Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder is mixed and then annealed, including: The 0.05-0.25 at% Cu-PbTe powder was mixed with the Cu 0.004 Pb 0.99 Sn 0.01 Se 0.5 Te 0.25 S 0.25 @PDA powder is mixed in anhydrous ethanol and then dried to obtain a mixed powder; The mixed powder was annealed at 280-320 °C for 2.5-4.0 h in a hydrogen-argon mixed atmosphere.

7. The preparation method according to claim 3, characterized in that, Also includes: The carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe powder is subjected to hot pressing to obtain a carbon-coated high-entropy second-phase composite Cu-doped n-type PbTe bulk.

8. The preparation method according to claim 7, characterized in that, The hot pressing process includes: Under vacuum conditions with an axial pressure of 45-55 MPa and a pressure below 10 Pa, hot press at a constant temperature of 500-600℃ for 10 min. The heating rate of the hot pressing process is 80-120℃ / minute.

9. The preparation method according to any one of claims 3-8, characterized in that, 0.15 at% Cu-PbTe powder was prepared by vacuum melting method.

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