阅读说明：本技术 一种p-n热电纱线及其制备方法和应用 (P-n thermoelectric yarn and preparation method and application thereof ) 是由 刘宇 余弘 闫畅 胡海蓉 于 2021-09-03 设计创作，主要内容包括：本发明公开了一种p-n热电纱线,所述p-n热电纱线是以碳纳米管纱线为基体,分别以PEI溶液和FeCl-(3)溶液作为n型改性剂和p型改性剂进行改性处理,并以银涂层作为电极连接n型纱线段和p型纱线段而得到。本发明还公开的所述p-n热电纱线的制备方法及其应用。本发明的p-n热电纱线的制备方法简单易行,所得的p-n热电纱线具有规模化的连续结构,能够与间隔织物组装形成热电器件,捕捉人体余热并将其转换成电能,在可穿戴领域具有重要的科学价值和广泛应用前景。(The invention discloses a p-n thermoelectric yarn, which takes carbon nanotube yarn as a substrate and respectively takes PEI solution and FeCl as raw materials 3 The solution is used as an n-type modifier and a p-type modifier for modification treatment, and the silver coating is used as an electrode to connect the n-type yarn segment and the p-type yarn segment. The invention also discloses a preparation method and application of the p-n thermoelectric yarn. The preparation method of the p-n thermoelectric yarn is simple and feasible, the obtained p-n thermoelectric yarn has a large-scale continuous structure, can be assembled with the spacer fabric to form a thermoelectric device, captures the waste heat of a human body and converts the waste heat into electric energy, and has important scientific value and wide application prospect in the wearable field.)

1. The p-n thermoelectric yarn is characterized in that the p-n thermoelectric yarn takes carbon nanotube yarn as a substrate and respectively takes PEI solution and FeCl solution₃The solution is used as an n-type modifier and a p-type modifier for modification treatment, and the silver coating is used as an electrode to connect the n-type yarn segment and the p-type yarn segment.

2. The p-n thermoelectric yarn of claim 1 wherein the p-type and n-type yarn segments alternate in sequence, adjacent p-type and n-type yarn segments being separated by a silver coating.

3. A method of making a p-n thermoelectric yarn as claimed in claim 1 or 2, characterized in that it comprises the steps of:

s1: twisting and fixing the carbon nanotube film by a wet method to obtain large-scale continuous carbon nanotube yarn;

s2: fixing the carbon nano tube yarn obtained in S1 on a template, and respectively using PEI solution and FeCl₃The solution is used as an n-type modifier and a p-type modifier, is subjected to physical adsorption modification at high temperature, is cooled to room temperature, and is connected with an n-type yarn segment and a p-type yarn segment by taking a silver coating as an electrode to obtain the p-n thermoelectric yarn.

4. The method of claim 3, wherein deionized water is continuously sprayed to wet the carbon nanotube film during the wet twisting in step S1, the twisting speed is 300-1250 rpm, and the twist value is 500-1200 twist/m.

5. The preparation method according to claim 3, wherein the temperature for fixing and forming the carbon nanotube yarn in the step S1 is 30-80 ℃, and the fixing and forming time is 6-48 h.

6. The manufacturing method according to claim 3, wherein the size of the template used in step S2 is: the width is 4-20 mm, and the thickness is 0.2-2 mm.

7. The method according to claim 3, wherein the temperature of the modification in the step S2 is 100 to 160 ℃; the concentration of the n-type modification reagent PEI solution is 1-15 wt.%; the p-type modifying reagent FeCl₃The concentration of the solution is 10-50 wt.%.

8. The method according to claim 3, wherein in step S2:

the physical adsorption modification is to use a high-temperature resistant brush to respectively carry out PEI solution and FeCl₃The solution is brushed and coated on the surfaces of the carbon nanotube yarns on the upper surface and the lower surface of the template;

the silver coating is used as an electrode to connect the n-type yarn section and the p-type yarn section, and high-conductivity silver paste is brushed on the surface of the carbon nano tube yarn on the side face of the template to form the silver coating.

9. The method as claimed in claim 8, wherein the material of the brush is selected from: nylon (PA), polyethylene terephthalate (PBT), Polyethylene (PE), silicone, and hog bristle brushes.

10. The method according to claim 8, wherein the brushing speed is 0.5 to 5 cm/s.

11. Use of a p-n thermoelectric yarn according to claim 1 or 2 for the preparation of a flexible thermoelectric fabric.

Technical Field

The invention belongs to the field of thermoelectric materials and preparation and application thereof, and particularly relates to a p-n thermoelectric yarn and a preparation method and application thereof.

Background

The development and popularity of 5G technology is opening the world of everything interconnection, and portable electronic devices are therefore expanding. At present, chemical batteries commonly used in portable electronic devices can generate a large amount of toxic and harmful substances in the production and scrapping processes, and the chemical batteries are inconsistent with the current era background of green energy. The direct conversion of energy in the environment into electrical energy and the supply of energy to microelectronics are the development direction of wearable devices in the future. The human body is a huge energy source and the heat power emitted to the environment is about 2.5W per day. The conversion of human body waste heat into usable electricity has received much attention, but human body and environment can only form low temperature difference heat energy, and thus it is difficult to capture effectively.

Thermoelectric materials have been widely studied for sensing and converting various kinds of thermal energy due to temperature differences, among which semiconductor materials are excellent in thermoelectric properties and have been applied to commercial thermoelectric devices. Semiconductor materials can be divided into two classes by conductivity type: p-type semiconductors and n-type semiconductors. p-type semiconductors are also referred to as hole-type semiconductors, in which holes are majority electrons and free electrons are minority electrons, and conduction is mainly by holes. The p-type semiconductor obtained by doping modification is an extrinsic semiconductor, holes of the p-type extrinsic semiconductor are mainly provided by impurity atoms, and free electrons are formed by thermal excitation. The more impurities are doped, the higher the concentration of the majority (holes) and the stronger the conductivity. The same applies to n-type semiconductors. Therefore, the physical properties of the semiconductor material can be regulated and controlled through impurity atom doping, and the semiconductor material with excellent thermoelectric property is obtained.

At present, bulk thermoelectric materials and devices have been applied to the fields of aerospace, mechanical plane heat source capture and the like due to high heat energy conversion efficiency, but the defects of heavy weight and rigidity limit the application of the bulk thermoelectric materials and devices in the wearable field. Therefore, flexible thermoelectric materials and devices have been extensively studied by virtue of efficient curved surface adaptability. However, the flexible thermoelectric materials and devices reported at present can only convert heat energy in the plane direction of a heat source, and when the flexible thermoelectric materials and devices are applied to human body heat energy capture, a series of defects of low efficiency, poor comfort and the like exist. Therefore, there is a need to develop a material structure and a device capable of capturing the residual heat of the human body in the direction of temperature difference.

Disclosure of Invention

The invention aims to solve the technical problem of providing a continuous p-n thermoelectric yarn and a preparation method and application thereof, so as to solve the problem that flexible thermoelectric materials and devices in the prior art can only convert heat energy in the plane direction of a heat source.

In order to achieve the above object, according to a first aspect of the present invention, there is provided a p-n thermoelectric yarn, wherein the p-n thermoelectric yarn is based on carbon nanotube yarn, and PEI solution and FeCl solution are used as matrix, respectively₃The solution is used as an n-type modifier and a p-type modifier for modification treatment, and the silver coating is used as an electrode to connect the n-type yarn segment and the p-type yarn segment.

According to the invention, the p-type and n-type yarn segments alternate in sequence, adjacent p-type and n-type yarn segments being separated by a silver coating.

In a second aspect of the invention, a method for preparing the p-n thermoelectric yarn is provided, which comprises the following steps:

s1: twisting and fixing the carbon nanotube film by a wet method to obtain large-scale continuous carbon nanotube yarn;

s2: fixing the carbon nano tube yarn obtained in S1 on a template, and respectively using PEI solution and FeCl₃The solution is used as an n-type modifier and a p-type modifier, is subjected to physical adsorption modification at high temperature, is cooled to room temperature, and is connected with the n-type yarn segment and the p-type yarn segment by taking the silver coating as an electrode to obtain the p-n thermoelectric yarn.

According to the invention, deionized water is continuously sprayed to wet the carbon nanotube film in the wet twisting process in the step S1, the twisting speed is 300-1250 r/min, and the twist value is 500-1200 twist/m.

According to the invention, the temperature for fixing and forming the carbon nanotube yarn in the step S1 is 30-80 ℃, and the fixing and forming time is 6-48 h.

According to the invention, the size of the template used in step S2 is: the width is 4-20 mm, and the thickness is 0.2-2 mm.

According to the invention, the temperature of modification in the step S2 is 100-160 ℃; the concentration of the n-type modification reagent PEI solution is 1-15 wt.%; the p-type modifying reagent FeCl₃The concentration of the solution is 10-50 wt.%.

According to the preferred embodiment of the present invention, in step S2:

the articleThe physical adsorption modification is to use a high-temperature resistant brush to respectively carry out PEI solution and FeCl₃The solution is brushed and coated on the surfaces of the carbon nanotube yarns on the upper surface and the lower surface of the template;

the silver coating is used as an electrode to connect the n-type yarn section and the p-type yarn section, and high-conductivity silver paste is brushed on the surface of the carbon nano tube yarn on the side face of the template to form the silver coating.

According to the invention, the material of the high temperature resistant brush is selected from: nylon (PA), polyethylene terephthalate (PBT), Polyethylene (PE), silicone, and hog bristle brushes.

According to the invention, the brushing speed is 0.5-5 cm/s.

In a third aspect of the invention, the use of said p-n thermoelectric yarn for the preparation of a flexible thermoelectric fabric is provided.

The invention has the following beneficial effects:

1. the preparation method of the p-n thermoelectric yarn is simple and easy to implement, and the obtained p-n thermoelectric yarn has a scaled continuous structure, wherein the carbon nanotube yarn is used as a matrix, and PEI and FeCl are added₃The solution is used as an n-type modifier and a p-type modifier respectively, and the silver coating is used as an electrode to connect the p-type segment and the n-type segment.

2. The p-n thermoelectric yarn can be assembled with the spacer fabric to form a thermoelectric device, captures the waste heat of a human body and converts the waste heat into electric energy, and has important scientific value and wide application prospect in the wearable field.

3. The continuous p-n thermoelectric yarn obtained by modifying the carbon nanotube yarn in sections not only can exert the excellent electrical and mechanical properties of the carbon nanotube, but also has the sectional electron and hole conducting characteristics, and can improve the thermoelectric conversion efficiency of the yarn.

4. The preparation method is simple in preparation process, environment-friendly, pollution-free, suitable for industrial production and low in cost.

5. The continuous thermoelectric yarn can directly capture the waste heat of the human body, and can also be applied to the fields of sunlight heat, mechanical waste heat conversion and the like.

Drawings

Fig. 1 is a schematic view showing a modification of a thermoelectric yarn in example 1.

Fig. 2a is a photomicrograph of a p-n thermoelectric yarn made in example 1, and fig. 2B is a schematic illustration of the corresponding partial construction.

Fig. 3 is an SEM photograph of the carbon nanotube yarn and the thermoelectric yarn prepared in example 2; wherein FIG. 3a is a low power SEM photograph of the surface of the carbon nanotube yarn, FIG. 3b is a high power SEM photograph of the carbon nanotube yarn, FIG. 3c is a high power SEM photograph of the PEI-modified carbon nanotube yarn, and FIG. 3d is a FeCl₃High power SEM photograph of the modified carbon nanotube yarn.

FIG. 4 shows the Seebeck coefficient and mechanical properties of the thermoelectric yarn prepared in example 3; fig. 4a shows seebeck coefficients of the carbon nanotube yarn, the p-type segment thermoelectric yarn and the n-type segment thermoelectric yarn, and fig. 4b shows a stress-strain curve of the continuous thermoelectric yarn.

FIG. 5 shows the thermoelectric fabric prepared in example 4 and the output performance; wherein, fig. 5a is a physical diagram of the thermoelectric fabric, and fig. 5b is an output voltage of the thermoelectric fabric under different temperature differences.

Description of the figure numbers:

1-carbon nanotube yarn; 2-high temperature resistant brush; 3-silver coating; 4-n type yarns; 5-template; 6-p type yarns; 7-heating the table.

Detailed Description

The invention is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

The carbon nanotube films, PEI (Mw 600) and FeCl3 (. gtoreq.98%) used in the following examples are available from conventional commercial sources, for example, carbon nanotube films are available from Jiidi nanotechnology, Suzhou, PEI (Mw 600) and FeCl3 (. gtoreq.98%) are available from Shanghai Tantake technologies, Inc.

In the following examples, PEI solution (polyethyleneimine solution) and FeCl for physical high-temperature adsorption modification₃All solutions are adopted to beAnd preparing the product by using water ethanol as a solvent.

The materials used in the following examples were selected from: nylon (PA), polyethylene terephthalate (PBT), Polyethylene (PE), silicone, and bristle brushes, among others.

EXAMPLE 1 preparation of p-n thermoelectric yarn

S1, fastening two ends of the carbon nano tube film with the length and the width of 1 multiplied by 0.5m on a twisting machine, setting the twisting twist value to be 500 twists/m, and twisting at the speed of 300 turns/min; and continuously spraying deionized water to wet the carbon nanotube film during twisting, placing the carbon nanotube film in an environment of 30 ℃ after twisting is finished, fixing and forming for 6 hours, and naturally cooling to room temperature to obtain the carbon nanotube yarn.

S2, referring to fig. 1, the carbon nanotube yarn 1 obtained in S1 was spirally wound on a template 5 having a width and thickness of 4 × 0.2mm, and placed on a hot stage 7 at 100 ℃. For n-type modification, a high-temperature resistant brush 2 is used for dipping a PEI solution with the concentration of 1 wt.%, and the PEI solution is uniformly brushed on the surface of the carbon nano tube yarn 1 above the template 5 at the speed of 0.5cm/s to form an n-type yarn 4; for the p-type modification, after the template 5 is turned over, FeCl with a concentration of 10 wt.% is dipped by a high temperature resistant brush 2₃And (3) coating the solution on the surface of the carbon nanotube yarn 1 above the overturned template 5 at a speed of 0.5cm/s to form a p-type yarn 6. And cooling to room temperature, and brushing high-conductivity silver paste on the surface of the carbon nanotube yarn 1 on the side surface of the template 5 to form a silver coating 3. As shown in fig. 2a and 2b, the p-n thermoelectric yarn is obtained in which p-type yarn segments and n-type yarn segments alternate in sequence, adjacent p-type yarn segments and n-type yarn segments are separated by a silver coating 3, and the silver coating 3 simultaneously serves as an electrode.

And assembling continuous p-n thermoelectric yarns with the length of 4mm in a wavy structure on the spacer fabric, wherein the adjacent silver coatings are respectively positioned at the lowest point and the lowest point adjacent to the wavy structure, so as to obtain the flexible thermoelectric fabric.

Example 2 preparation of p-n thermoelectric yarn

S1, fastening two ends of the carbon nano tube film with the length and width of 1.5 multiplied by 0.5m on a twisting machine, setting the twisting twist value to be 800 twists/m, and twisting at the speed of 600 turns/min; and continuously spraying deionized water to wet the carbon nanotube film during twisting, placing the carbon nanotube film in an environment of 50 ℃ after twisting is finished, fixing and forming for 20 hours, and naturally cooling to room temperature to obtain the carbon nanotube yarn.

S2, the carbon nanotube yarn obtained in S1 was spirally wound on a template having a width and thickness of 9X 0.8mm, and placed on a 120 ℃ hot stage. For n-type modification, a high-temperature-resistant brush is used for dipping PEI solution with the concentration of 5 wt.%, and the PEI solution is uniformly brushed on the surface of the carbon nano tube yarn above the template at the speed of 2.0 cm/s; for p-type modification, after the template was turned over, FeCl was dipped in 25 wt.% concentration with a high temperature brush₃And (3) brushing the solution on the surface of the carbon nano tube yarn above the overturned template at the speed of 2.0 cm/s. And cooling to room temperature, and brushing high-conductivity silver paste on the surface of the carbon nanotube yarn on the side surface of the template to form a silver coating. In the obtained p-n thermoelectric yarn, p-type yarn segments and n-type yarn segments are sequentially alternated, adjacent p-type yarn segments and n-type yarn segments are separated by silver coatings, and the silver coatings simultaneously serve as electrodes.

And assembling continuous p-n thermoelectric yarns with the length of 9mm in a wave-shaped structure on the spacer fabric, wherein the adjacent silver coatings are respectively positioned at the lowest point and the lowest point adjacent to the wave-shaped structure, so as to obtain the flexible thermoelectric fabric.

Fig. 3 shows SEM photographs of the carbon nanotube yarn and the thermoelectric yarn according to the present example. Wherein, fig. 3a is a low-power SEM photograph of the surface of the carbon nanotube yarn, fig. 3b is a high-power SEM photograph of the carbon nanotube yarn, fig. 3c is a high-power SEM photograph of the PEI modified carbon nanotube yarn, and fig. 3d is a high-power SEM photograph of the FeCl3 modified carbon nanotube yarn. The twisted yarn has better evenness, modified PEI is evenly coated on the surface of the carbon nano tube, and FeCl₃Cannot be represented in SEM pictures due to the smaller ion size.

Example 3 preparation of p-n thermoelectric yarn

S1, fastening two ends of the carbon nano tube film with the length and width of 1.8 multiplied by 0.8m on a twisting machine, setting the twisting twist value to be 1000 twists/m, and twisting at the speed of 950 turns/min; and continuously spraying deionized water to wet the carbon nanotube film during twisting, placing the carbon nanotube film in an environment of 70 ℃ after twisting is finished, fixing and forming for 34h, and naturally cooling to room temperature to obtain the carbon nanotube yarn.

S2, the carbon nanotube yarn obtained in S1 was spirally wound on a template having a width and thickness of 15X 1.5mm, and placed on a hot stage at 140 ℃. For n-type modification, a high-temperature-resistant brush is used for dipping a 10 wt.% PEI solution, and the solution is uniformly brushed on the surface of the carbon nano tube yarn above the template at a speed of 3.5 cm/s; for p-type modification, the template was turned over and FeCl was dipped in 40 wt.% FeCl using a high temperature brush₃And brushing the solution on the surface of the carbon nano tube yarn above the overturned template at the speed of 3.5 cm/s. And cooling to room temperature, and brushing high-conductivity silver paste on the surface of the carbon nanotube yarn on the side surface of the template to form a silver coating. In the obtained p-n thermoelectric yarn, p-type yarn segments and n-type yarn segments are sequentially alternated, adjacent p-type yarn segments and n-type yarn segments are separated by silver coatings, and the silver coatings simultaneously serve as electrodes.

And assembling the continuous p-n thermoelectric yarns with the length of 15mm in a wave-shaped structure on the spacer fabric, wherein the adjacent silver coatings are respectively positioned at the lowest point and the lowest point adjacent to the wave-shaped structure, so as to obtain the flexible thermoelectric fabric.

Figure 4 shows the seebeck coefficient and mechanical properties of the p-n thermoelectric yarn obtained in this example. Wherein, fig. 4a is the seebeck coefficient of the carbon nanotube yarn, the p-type segment and the n-type segment thermoelectric yarn, and fig. 4b is the stress-strain curve of the continuous thermoelectric yarn. It can be seen that the Seebeck coefficient of the p-type section of the modified yarn is increased to a certain extent, while the Seebeck coefficient of the n-type section is changed into a negative value; the breaking strength of the thermoelectric yarn is more than 250MPa, and the mechanical strength requirement in wearable application is met.

Example 4 preparation of p-n thermoelectric yarn

S1, fastening two ends of the carbon nano tube film with the length and the width of 2 multiplied by 1m on a twisting machine, setting the twisting twist value to be 1200 twist/m, and twisting at the speed of 1250 revolutions/min; and continuously spraying deionized water to wet the carbon nanotube film during twisting, placing the carbon nanotube film in an environment of 80 ℃ after twisting is finished, fixing and forming for 48 hours, and naturally cooling to room temperature to obtain the carbon nanotube yarn.

S2, the carbon nano tube yarn obtained in the S2 is spirally wound on a template with the width and thickness of 20 multiplied by 2mm, and is placed on a hot table at 160 ℃. For n-type modification, a high-temperature-resistant brush is used for dipping a PEI solution with the concentration of 15 wt.%, and the PEI solution is uniformly brushed on the surface of the carbon nano tube yarn above the template at the speed of 5 cm/s; for p-type modification, after the template was turned over, FeCl was dipped in a concentration of 50 wt.% with a high temperature brush₃And brushing the solution on the surface of the carbon nano tube yarn above the turned template at the speed of 5 cm/s. And cooling to room temperature, and brushing high-conductivity silver paste on the surface of the carbon nanotube yarn on the side surface of the template to form a silver coating. In the obtained p-n thermoelectric yarn, p-type yarn segments and n-type yarn segments are sequentially alternated, adjacent p-type yarn segments and n-type yarn segments are separated by silver coatings, and the silver coatings simultaneously serve as electrodes.

And assembling the continuous p-n thermoelectric yarns with the length of 20mm in a wave-shaped structure on the spacer fabric, wherein the adjacent silver coatings are respectively positioned at the lowest point and the lowest point adjacent to the wave-shaped structure, so as to obtain the flexible thermoelectric fabric.

Fig. 5 shows the thermoelectric fabric made of the p-n thermoelectric yarn obtained in the present embodiment and the output performance, wherein fig. 5a is a physical diagram of the thermoelectric fabric, and fig. 5b is the output voltage of the thermoelectric fabric at different temperature differences. It can be seen that the thermoelectric yarn assembled in a wave shape in the spacer fabric can generate about 23mV of voltage at a temperature difference of 14.4K.

Comparative example 1

The p-n thermoelectric yarn prepared in example 3 was compared to thermoelectric yarns prepared in the literature (Nature Communication,2020,11, 572): in the literature, n-type modification is realized by an electrostatic spraying oleylamine method, the freezing point of oleylamine is 15-20 ℃, and the carbon nano tube cannot be modified at a lower temperature; and the electrostatic spraying has higher requirements on the environment and equipment. The modification method by brushing PEI in example 3 is simple and efficient, and can be popularized to industrial application.

Comparative analysis shows that the thermoelectric yarn method is more suitable for future industrial preparation.

Comparative example 2

The p-n thermoelectric yarn prepared in example 3 was compared to thermoelectric yarn prepared in the literature (Nature Communication,2020,11, 6006): the maximum breaking strength of the thermoelectric yarn prepared by the gel extrusion process in the literature is about 35MPa, and the optimal output voltage of the assembled thermoelectric fabric is about 8mV at a temperature difference of 15K. Whereas the breaking strength of the thermoelectric yarn of example 3 was greater than 250MPa, the output voltage of the assembled thermoelectric fabric was about 23mV at a temperature difference of 14.4K.

Comparative analysis shows that the mechanical property and the fabric output performance of the thermoelectric yarn are far higher than those of thermoelectric yarns and devices reported in the literature.