Three-dimensional structured metal selenide flexible thermoelectric material, preparation method and application thereof

Abstract

The application provides a three-dimensional structured metal selenide flexible thermoelectric material and a preparation method and application thereof. 2+ The preparation method comprises the following steps: pretreating a flexible substrate with an alkali solution, and obtaining a substrate material after cleaning; dissolving a tin salt in water to prepare a Sn n solution, then adding acid until the solution becomes clear, immersing the substrate material in the clear solution for more than 10 min, and then cleaning and drying to obtain a template; depositing metal X on the surface of the template and the inner surface of the holes of the template to obtain a metalized substrate; wherein X is at least one of Cu, Ag and Sn; immersing the metalized substrate in a selenium solution for soaking, and reacting to obtain a three-dimensional structured X n Se metal selenide flexible thermoelectric material, wherein 2 >= n >= 1. By adopting the technical scheme of the application, the obtained thermoelectric material has high porosity, low density, low thermal conductivity and excellent flexibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermoelectric materials, in particular to a three-dimensional structure metal selenide flexible thermoelectric material and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of the Internet of Things technology, wearable electronic devices, flexible electronic devices, electronic skin and other devices have entered people's lives. Flexible thermoelectric materials can directly convert human body surface heat into electrical energy, have the advantages of no working fluid, no moving parts, quiet operation, maintenance-free, light weight and fast response time, and can be used for power supply of flexible electronic devices. Developing flexible thermoelectric materials with high thermoelectric performance, high flexibility, high reliability, low production cost and batch production is the key to its large-scale application.

[0003] The current flexible thermoelectric materials can be divided into two categories: inorganic thermoelectric materials and organic thermoelectric materials. Among them, the inorganic flexible thermoelectric material is mainly a thermoelectric film, and the common preparation methods include magnetron sputtering method, electroplating method, etc. These methods usually involve high vacuum technology and special equipment, and the production cost is high and it is difficult to realize batch production. In addition, Ag2Se nanowires can also be prepared by synthesizing selenium nanowires and further reacting with silver. This way has more synthesis steps, complex process, and requires a long reaction time, and the production efficiency is low. Moreover, general inorganic thermoelectric materials do not have flexibility and elasticity. Organic thermoelectric materials include conductive polymers such as PEDOT:PSS. Although these materials can be prepared by solution-based methods and have excellent mechanical properties, the intrinsic Seebeck coefficient is low, and the thermoelectric performance is poorer than inorganic materials. SUMMARY

[0004] In view of the above technical problems, the present application discloses a three-dimensional structure metal selenide flexible thermoelectric material and a preparation method and application thereof. The metal selenide thermoelectric material with three-dimensional network structure is prepared by two-step soaking method, has large porosity, small density and good thermal insulation performance; low cost, simple process, and batch production.

[0005] To this end, the technical scheme adopted by the present application is as follows:

[0006] A preparation method of a three-dimensional structure metal selenide flexible thermoelectric material, comprising the following steps:

[0007] Step S1, pretreat the flexible substrate with an alkali solution, and obtain a substrate material after cleaning; dissolve tin salt in water to prepare a Sn 2+ solution, then add acid until the solution becomes clear, immerse the substrate material in the clear solution for more than 10 minutes, then clean and dry to obtain a template;

[0008] Step S2, depositing metal X on the surface of the template and the inner surface of the template hole obtained in step S1 to obtain a metalized substrate; wherein element X is at least one of Cu, Ag and Sn;

[0009] Step S3, soaking the metalized substrate obtained in step S2 in a selenium solution to obtain a three-dimensional structure of X n Se metal selenide flexible thermoelectric material, wherein 2 > n > 1.

[0010] By using the technical scheme, the three-dimensional structure of the metal selenide thermoelectric material prepared by the two-step soaking method has a large porosity, a small density and a good heat insulation performance. The small density can make the wearable thermoelectric device lightweight, and the good heat insulation performance ensures that the material has the ability to establish a temperature difference under natural convection. In step S1, the first soaking plays a sensitization role, and the liquid enters the gap for more than 10 minutes to make the plating layer uniform in the second step. In addition, the three-dimensional structure of the technical scheme can be obtained by micro-scale deformation to achieve macro tensile or compression, so that the inorganic thermoelectric material has flexibility or even elasticity.

[0011] Secondly, the preparation process of the technical scheme can be operated in a room temperature air environment and does not depend on electrical equipment, so that the processing place and sample size are not limited, and large-scale production can be realized. At the same time, the method is compatible with most flexible fabrics, or polymer skeletons, foams and other substrates, and the flexible materials can be easily processed into flexible thermoelectric materials. In addition, the prepared thermoelectric material can be processed into different shapes to meet different use requirements, and the difficulty of shape processing caused by the brittleness of traditional inorganic thermoelectric materials is overcome.

[0012] As a further improvement of the present application, in step S1, the acid is preferably hydrochloric acid.

[0013] As a further improvement of the present application, in step S3, the selenium solution is prepared by adding selenium powder and sodium sulfide nonahydrate into deionized water to obtain Se. Different soaking times can obtain three-dimensional structures of X with different n values n Se metal selenide flexible thermoelectric material, when X is Ag, the soaking time is less than 10h, the obtained metal selenide n < 2, when the soaking time is greater than or equal to 10h, the obtained metal selenide n = 2; when X is Cu, the soaking time is 2-10min, Cu2Se metal selenide flexible thermoelectric material can be obtained. By using the technical scheme, different proportions of X can be obtained according to the reaction time. n Se metal selenide flexible thermoelectric material.

[0014] As a further improvement of the present application, the flexible substrate is a fabric, a sponge, an aerogel or the like, wherein the fabric can be a cotton fabric, a linen fabric or a silk fabric.

[0015] As a further improvement of the present application, in step S1, the pre-treatment comprises: soaking the flexible substrate in NaOH solution for 30 min, and then washing with deionized water.

[0016] As a further improvement of the present application, step S2 comprises: configuring a silver-ammonia solution and a reducing agent solution, immersing the template obtained in step S1 in a mixture of the reducing agent solution and the silver-ammonia solution, squeezing out residual air bubbles, washing and drying after the silver mirror reaction is completed, to obtain a silver-plated substrate.

[0017] As a further improvement of the present application, the reducing agent solution is prepared by dissolving glucose, sodium potassium tartrate tetrahydrate, and polyethylene glycol in an ethanol solution; and the silver-ammonia solution is obtained by mixing silver nitrate, sodium hydroxide, and ammonia water.

[0018] As a further improvement of the present application, step S2 further comprises: immersing the silver-plated substrate again in the mixture of the reducing agent solution and the silver-ammonia solution for multiple times of silver plating. Further preferably, the number of silver plating is 1-3 times.

[0019] As a further improvement of the present application, in the reducing agent solution, the concentrations of C6H 12 O6·H2O, C4H4O6KNa·4H2O, PEG1000, and ethanol are 20-60 g / L, 10-20 g / L, 0.05-0.3 g / L, and 90-100 g / L, respectively.

[0020] As a further improvement of the present application, in step S2, in the silver-ammonia solution, the concentration of silver nitrate is 30-50 g / L, the concentration of NaOH is 10-25 g / L, and the concentration of ammonia water is 2-7 mol / L.

[0021] As a further improvement of the present application, in step S2, the silver mirror reaction time, i.e., the silver plating time, is 1-3 h.

[0022] As a further improvement of the present application, step S1 further comprises: after naturally drying the template, activating the template in a palladium chloride solution, and naturally air-drying after activation. Further, the concentration of the palladium chloride solution is 0.2-0.4 g / L. Further preferably, the concentration of the palladium chloride solution is 0.3 g / L.

[0023] As a further improvement of the present application, step S2 comprises: configuring a chemical copper plating solution, adding a copper reducing agent, immersing the template obtained in step S1 in a mixture of the reducing agent and the chemical copper plating solution, squeezing out residual air bubbles, washing and drying after the reaction is completed, to obtain a copper-plated substrate.

[0024] As a further improvement of the present application, step S2 comprises configuring a chemical tin plating solution, adding a tin reducing agent, immersing the template obtained in step S1 in a mixture of the reducing agent and the chemical tin plating solution, extruding residual bubbles, and after the reaction is completed, cleaning, drying to obtain a tin plated substrate.

[0025] As a further improvement of the present application, the chemical copper plating solution is prepared by dissolving copper sulfate, sodium potassium tartrate tetrahydrate and polyethylene glycol in an ethanol solution; and the copper reducing agent is formaldehyde.

[0026] As a further improvement of the present application, in step S2, for the technical solutions of copper plating and tin plating, multiple copper plating or tin plating can be performed.

[0027] The present application also discloses a three-dimensional metal selenide flexible thermoelectric material prepared by the preparation method of the three-dimensional metal selenide flexible thermoelectric material.

[0028] The present application also discloses an application of the three-dimensional metal selenide flexible thermoelectric material as described above, which is used in wearable electronic devices, flexible electronic devices and electronic skin.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] First, by using the technical solution of the present application, the prepared thermoelectric material has a high porosity structure, extremely low density, extremely low thermal conductivity and excellent flexibility. Thanks to the above advantages, the thermoelectric device based on the thermoelectric material has the characteristics of high output power, light weight, soft texture and good reliability.

[0031] Second, the technical solution of the present application uses a two-step immersion method to prepare the thermoelectric material. This method is simple to operate, can be batch produced, has low production cost and is not limited by large equipment. Moreover, this method is universal and can be compatible with various fabric substrates and polymer materials, so that common clothes, fabrics and textiles can be simply processed into thermoelectric material thermoelectric devices. Moreover, the thermoelectric material produced by this method can be subjected to secondary special processing to adapt to different service environments. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Fig. 1 is a picture of a metal selenide flexible thermoelectric material sample prepared by the embodiment 1 of the present application, wherein (a) is a large-size sample prepared, and (b) is a special-shaped sample processed.

[0033] Figure 2 Fig. 2 is a thermoelectric network microstructure characterization of the metal selenide flexible thermoelectric material prepared by the embodiment 1 of the present application, wherein (a) is a sample micro-morphology diagram, (b) is a local detail enlarged view, and (c) is a pore area statistical diagram.

[0034] Figure 3 These are partial enlarged views of flexible thermoelectric materials made from different fabric substrates according to embodiments of the present invention, wherein (a) is cotton fabric, (b) is linen fabric, and (c) is silk fabric.

[0035] Figure 4 The mechanical properties characterization results of the Ag2Se flexible thermoelectric material prepared in Example 1 of this invention are shown below. (a) is the resistance change curve under different stress and strain conditions; (b) is the stress-strain curve after cyclic testing with different strain conditions; (c) is the stress-strain curve after cyclic testing with maximum strain; and (d) is the resistance change curve under different stress-strain cycles. Wherein ε... t This represents the tension at this strain (50%, 100%), ε c This indicates compression at that strain (50%, 80%).

[0036] Figure 5 These are the thermoelectric performance results of the Ag2Se flexible thermoelectric material prepared in Example 1 of the present invention, where (a) is resistivity and Zebeck coefficient, and (b) is power factor and zT.

[0037] Figure 6 These are the thermoelectric performance results of the Cu2Se flexible thermoelectric material prepared in Example 2 of the present invention, where (a) is resistivity and Zebeck coefficient, and (b) is power factor and zT.

[0038] Figure 7 These are the electrical performance results of the wearable thermoelectric device prepared in Example 3 of the present invention, where (a) is the measured open-circuit voltage and (b) is the measured power density.

[0039] Figure 8 The following are performance characterizations of Ag2Se flexible thermoelectric materials obtained by different preparation processes in Example 4 of this invention, wherein (a) is the silver load with different ammonia concentrations, (b) is the silver load with different silver plating times, (c) is the silver selenide load with different silver plating times, (d) is the density of samples prepared with different silver plating times, (e) is the porosity calculated from the sample density in Figure (d), and (f) is the resistivity of samples obtained with different silver plating times. Detailed Implementation

[0040] The preferred embodiments of the present invention will be described in further detail below.

[0041] The technical solution of this invention employs a two-step immersion method to prepare binary compound thermoelectric materials. The first element in the prepared compound can be, but is not limited to, one or a combination of silver (Ag), copper (Cu), and tin (Sn); the second element is, but is not limited to, selenium (Se). Specific details are provided below.

[0042] Example 1

[0043] A three-dimensional structure of Ag2Se flexible thermoelectric material is prepared by the following method:

[0044] Pre-treatment of the substrate: the flexible fabric is first immersed in NaOH solution for 30 min, and then washed with deionized water. SnCl2·2H2O is dissolved in deionized water (40 g / L) to prepare Sn 2+ solution, and then hydrochloric acid is added until the solution becomes clear. Then the substrate material is immersed in the Sn 2+ solution for 2 h, and then transferred to deionized water for washing. Finally, the treated substrate is naturally dried to obtain a template.

[0045] Surface metallization of the substrate: a first step is to deposit a metal layer on the outer surface and inner surface of the pores of the substrate by electroless silver plating.

[0046] First, C6H 12 O6·H2O, C4H4O6KNa·4H2O, and PEG1000 are dissolved in a dilute ethanol solution to prepare a reducing agent. A silver ammonia solution is prepared by mixing AgNO3, NaOH, and ammonia water. In this embodiment, the concentrations of C6H 12 O6·H2O, C4H4O6KNa·4H2O, PEG1000, and ethanol in the reducing agent are 40 g / L, 14 g / L, 0.1 g / L, and 100 g / L, respectively. The concentrations of AgNO3 and NaOH in the silver ammonia solution are 50 g / L and 25 g / L, respectively, and the concentration of ammonia water is 4.5 mol / L.

[0047] Second, the above template is immersed in a mixture of the reducing agent and the silver ammonia solution for reaction, and is gently squeezed to squeeze out residual air bubbles. After 3 h, when the silver mirror reaction is completed, the obtained silver-plated substrate is washed and dried. The reaction rate and the number of reactions affect the loading of silver, and thus affect the loading amount of Ag2Se. Therefore, the loading amount of silver can be adjusted by changing the ratio of reactants and the number of reactions.

[0048] In addition, the methods for plating copper and tin are similar to the above silver plating.

[0049] Selenization: a selenium solution is prepared by dissolving Na2S·9H2O and selenium powder in deionized water to obtain a selenium solution, and the concentration of selenium in the selenium solution is 20 g / L. Then the above metallized substrate is immersed in the selenium solution for 10 h to synthesize Ag2Se thermoelectric material. Considering the reaction efficiency, subsequent samples are prepared twice with a concentration of 4.4 mol / L of ammonia in the silver ammonia solution as a reference. The loading amount of Ag2Se can be adjusted by changing the ratio of reactants and the number of reactions.

[0050] In this embodiment, the concentration of sodium sulfide in the sodium sulfide solution is 60 g / L; and the concentration of selenium in the selenium solution is 20 g / L.

[0051] The large-size sample and the sample after special processing of the Ag2Se flexible thermoelectric material prepared in this embodiment are shown in Figure 1 .

[0052] Figure 2 is a thermoelectric network microstructure diagram of the Ag2Se flexible thermoelectric material, and it can be seen from Figure 2 (a) and Figure 2 (b) that there is a layer of thermoelectric material on the outer wall of the fabric fiber in the Ag2Se flexible thermoelectric material. It can be seen from Figure 2 (c) that the pore area of the material of this embodiment is mostly between 1000-2000 μm 2 .

[0053] The partial enlarged view of the flexible thermoelectric material made of different flexible fabrics in this embodiment is shown in Figure 3 , and it can be seen that the thermoelectric material is uniformly coated on the surface of the fabric fiber.

[0054] Generally speaking, three-dimensional inorganic thermoelectric materials do not have flexibility and elasticity. However, the structured thermoelectric material prepared by the method of this embodiment can realize stretching or compression on the macro scale by means of micro-scale structural deformation.

[0055] The stress-strain test of the Ag2Se flexible thermoelectric material obtained in this embodiment was carried out, and the results are shown in Figure 4 . It can be seen from the stress-strain curves of Figure 4 (b) and 4(c) that the tensile strain (ε t ) of the tested sample reaches 100%, and the compressive strain (ε c ) reaches 80%. It can be deduced from the stress-strain curve that the Young's modulus of the sample is about 0.03 MPa, which is considered to be an ideal modulus similar to human tissues. Such Young's modulus can make the thermoelectric device closely fit the uneven skin and reduce the influence of mechanical load. The relative resistance gradually increases under tensile strain and gradually decreases under compressive strain as the sample changes with the stretching. In addition, we also carried out resistance change tests of the material under different strains and resistance changes under different cyclic strains, as shown in Figure 4 (a), 4(d), and it can be seen that after experiencing continuous cyclic strain, the sample can still return to the initial state, and the conductivity also remains stable.

[0056] The thermoelectric performance test of the Ag2Se flexible thermoelectric material obtained in this embodiment was carried out, and the results are shown in Figure 5 . It can be seen that in the room temperature test, the Seebeck coefficient of the prepared Ag2Se sample reaches -130 V K-1 Meanwhile, due to its higher porosity, the thermal conductivity of the sample is only about 0.04 W m -1 K -1 The zT value of the three-dimensional flexible thermoelectric material or elastic material based on polymer composite reported in the prior art is mostly lower than 0.03, compared with which the two-step immersion method of Ag2Se in the embodiment achieves a room temperature zT of more than 0.1, achieving a large performance improvement.

[0057] Embodiment 2

[0058] On the basis of embodiment 1, the difference of the embodiment is that the template is plated with copper instead of silver. Specifically, it comprises the following steps:

[0059] Pre-treatment of the substrate: the flexible fabric, sponge or other substrate is first immersed in a NaOH solution for 30 min, and then washed with deionized water. Tin chloride dihydrate (SnCl2·2H2O) is dissolved in deionized water (40 g / L) to prepare a Sn 2+ solution, and then hydrochloric acid is added until the solution becomes clear. Then the substrate material is immersed in the Sn 2+ solution for 2 h, and then transferred to deionized water for washing. Finally, the treated substrate is naturally dried to obtain the template.

[0060] After the treated substrate is naturally dried, it is placed in a palladium chloride solution (0.3 g / L) for activation. After activation, it is naturally air-dried for use.

[0061] Metalization of the substrate surface: first, a metal layer is coated on the outside of the substrate by chemical copper plating. Specifically, copper sulfate (CuSO4), sodium potassium tartrate tetrahydrate (C4H4O6KNa·4H2O) and polyethylene glycol (PEG1000) are dissolved in a dilute ethanol solution to prepare a chemical copper plating solution. Formaldehyde (HCHO) is used as a reducing agent. The reducing agent is added to the chemical copper plating solution, and the concentrations of CuSO4, C4H4O6KNa·4H2O, PEG1000 and formaldehyde are 30 g / L, 14 g / L, 0.1 g / L and 10 g / L, respectively.

[0062] The activated template is immersed in a mixture of the reducing agent and the chemical copper plating solution, gently squeezed to squeeze out residual bubbles. After the reaction is completed, the obtained copper-plated substrate is washed and dried. The tin plating method is similar to the copper plating method.

[0063] Selenization: a selenium solution is prepared by dissolving sodium sulfide nonahydrate (Na2S·9H2O) and selenium powder in deionized water to obtain a selenium solution, wherein the concentration of selenium in the selenium solution is 20 g / L. Then the above metalized substrate is immersed in the above selenium solution for 2-10 min to synthesize the Cu2Se flexible thermoelectric material.

[0064] The Cu2Se flexible thermoelectric material obtained in the embodiment was subjected to thermoelectric performance test, and the results are shown in Figure 6 Figure 5 Compared with

[0065] Embodiment 3

[0066] A wearable thermoelectric device was prepared by using the Ag2Se flexible thermoelectric material obtained in Embodiment 1, specifically, the Ag2Se flexible thermoelectric material was used as a thermoelectric arm, copper foil was used as an electrode, and conductive silver paste was used in series.

[0067] The output characteristics of the device were tested in the embodiment, and the test results are shown in Figure 7 It can be seen that when the ambient temperature is 297K and 290K respectively, the measured open circuit voltage is 0.4mV and 0.8mV respectively, and the power density reaches 1μW cm -2 and 4μWcm -2 The measured open circuit voltage and the simulated predicted value are basically the same, which shows that the Seebeck coefficient of the thermoelectric material prepared in the embodiment and the internal temperature difference of the thermoelectric device are consistent with the simulation, and the difference in the slope of the measured current-voltage curve and the simulation curve is mainly due to the additional contact resistance. Due to the influence of the contact resistance, the power density of the thermoelectric device is also slightly lower than the simulation results, but the power density of the device based on the thermoelectric material prepared by the two-step immersion method is still comparable to the traditional rigid block filled thermoelectric generator.

[0068] Embodiment 4

[0069] In the embodiment, the concentration of the reactant was changed based on Embodiment 1.

[0070] Based on Embodiment 1, the concentration of ammonia water in the silver-ammonia solution was changed in the substrate surface metallization step, and the concentration of ammonia water was 2.2, 3.1, 3.8, 4.4, 5.0, 5.5, 5.9, 6.3, 6.7, 7.0mol / L respectively, and other conditions were unchanged. The silver load results of the obtained plating layer are shown in Figure 8 (a), it can be seen that when the concentration of ammonia water is 4-5mol / L, the silver load is the highest.

[0071] Based on Embodiment 1, the silver plating time was changed in the substrate surface metallization step, that is, the above template was immersed in the mixture of reducing agent and silver-ammonia solution for 1h, 2h and 3h, and the silver load results are shown in Figure 8 (b), it can be seen that when the silver plating time is 3h, the silver load is the highest.

[0072] ​On the basis of Example 1, in the step of metalizing the surface of the substrate, the number of silver plating is changed to be 1, 2 and 3 times respectively. Among them, the 2nd and 3rd times are the steps of repeating the surface metalization of the substrate for the template plated with silver for the first time, and the reaction is carried out by immersing in the mixture of reducing agent and silver ammonia solution for 1 time and 2 times. The results of silver selenide loading obtained after the step of selenization are shown in Table 2 Figure 8 As shown in Table 2 and Fig. (c), it can be seen that the silver selenide loading increases with the increase of the number of silver plating.

[0073] On the basis of Example 1, in the step of metalizing the surface of the substrate, the number of silver plating is changed to be 1, 2 and 3 times respectively. Among them, the 2nd and 3rd times are the steps of repeating the surface metalization of the substrate for the template plated with silver for the first time, and the reaction is carried out by immersing in the mixture of reducing agent and silver ammonia solution for 1 time and 2 times. The density of the Ag2Se thermoelectric material sample obtained after the step of selenization is shown in Table 3 Figure 8 As shown in Table 3 and Fig. (d), it can be seen that the density of the Ag2Se thermoelectric material sample increases with the increase of the number of silver plating. The porosity calculated by the density of the sample is shown in Table 4 Figure 8 As shown in Table 4 and Fig. (e), it can be seen that the porosity decreases with the increase of the number of silver plating. In addition, the resistivity of the Ag2Se thermoelectric material sample obtained by different number of silver plating is shown in Table 5 Figure 8 As shown in Table 5 and Fig. (f), it can be seen that the resistivity decreases with the increase of the number of silver plating.

[0074] The above is a further detailed description of the present application in combination with specific preferred embodiments, which cannot be regarded as limiting the specific implementation of the present application to these descriptions. For ordinary skilled in the art to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, which should be regarded as falling within the protection scope of the present application.

Claims

1. A method of making a three-dimensionally structured metal selenide flexible thermoelectric material, characterized by: The method comprises the following steps: Step S1, the flexible substrate is pretreated with an alkaline solution, and after cleaning, the substrate material is obtained; tin salt is dissolved in water to prepare Sn 2+ solution, then acid is added until the solution becomes clear, the substrate material is immersed in the clear solution for more than 10 min, then cleaned, dried, and the template is obtained; Step S2, depositing metal X on the surface and the inner surface of the holes of the template obtained in step S1 to obtain a metallized substrate; wherein element X is at least one of Cu, Ag and Sn; Step S3, the metalized substrate obtained in step S2 is immersed in a selenium solution for soaking, and a three-dimensional structure X n Se metal selenide flexible thermoelectric material, wherein 2≥n≥1.

2. The method of claim 1, wherein: In step S1, the pre-treatment comprises: soaking the flexible substrate in a NaOH solution for 30 minutes, and then cleaning with deionized water.

3. The method of claim 2, wherein the three-dimensional structured metal selenide flexible thermoelectric material is prepared by: Step S2 comprises: configuring a silver-ammonia solution and a reducing agent solution, immersing the template obtained in step S1 in a mixture of the reducing agent solution and the silver-ammonia solution, squeezing out residual air bubbles, cleaning and drying after the silver mirror reaction is completed to obtain a silver-plated substrate.

4. The method of claim 3, wherein: The reducing agent solution is prepared by dissolving glucose, sodium potassium tartrate tetrahydrate and polyethylene glycol in an ethanol solution; and the silver-ammonia solution is obtained by mixing silver nitrate, sodium hydroxide and ammonia water.

5. The method of claim 1, wherein: Step S1 further comprises: naturally drying the template and then activating it in a palladium chloride solution, and naturally air-drying after activation.

6. The method of claim 5, wherein the three-dimensional structured metal selenide flexible thermoelectric material is prepared by: Step S2 comprises: configuring a chemical copper plating solution and adding a copper reducing agent, immersing the template obtained in step S1 in a mixture of the reducing agent and the chemical copper plating solution, squeezing out residual air bubbles, cleaning and drying after the reaction is completed to obtain a copper-plated substrate. Alternatively, a chemical tin plating solution is configured and a tin reducing agent is added, the template obtained in step S1 is immersed in a mixture of the reducing agent and the chemical tin plating solution, residual air bubbles are squeezed out, and cleaning and drying are performed after the reaction is completed to obtain a tin-plated substrate.

7. The method of claim 6, wherein the three-dimensional structured metal selenide flexible thermoelectric material is prepared by: The chemical copper plating solution is prepared by dissolving copper sulfate, sodium potassium tartrate tetrahydrate and polyethylene glycol in an ethanol solution; and the copper reducing agent is formaldehyde.

8. The method of claim 1-7, wherein the method further comprises: In step S3, the selenium solution is prepared by adding selenium powder and sodium sulfide nonahydrate into deionized water, and X three-dimensional structures with different n values are obtained by using different soaking times n Se metal selenide flexible thermoelectric material, wherein 2≥n≥1.

9. A three-dimensionally structured metal selenide flexible thermoelectric material, characterized by: The three-dimensional metal selenide flexible thermoelectric material is prepared by using the preparation method of the three-dimensional metal selenide flexible thermoelectric material according to any one of claims 1-8.

10. Use of a three-dimensionally structured metal selenide flexible thermoelectric material according to claim 9, wherein: The three-dimensional metal selenide flexible thermoelectric material is used in wearable electronic devices, flexible electronic devices and electronic skins.

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