A thermoelectric fabric and a method of making the same

Abstract

The present application relates to a kind of thermoelectric fabric and its preparation method, belong to thermoelectric fabric technical field.The preparation method of the present application includes the following steps, S1, by dipping coating method, matrix yarn is respectively dipped in single-walled carbon nanotube aqueous slurry and multi-walled carbon nanotube / aqueous polyurethane composite slurry, carbon nanotube composite yarn is obtained by drying;S2, carbon nanotube composite yarn is wound on template, silver paste is coated at two side nodes, poly (3,4-ethylenedioxythiophene) : polystyrene sulfonic acid solution and polyethyleneimine alcohol solution are respectively coated on the surface of carbon nanotube composite yarn which is not coated with silver paste, thermoelectric yarn with PN interval structure is obtained by drying;S3, thermoelectric yarn with PN interval structure is implanted into three-dimensional warp-knitted interval fabric by embroidery process, and the thermoelectric fabric is obtained.The preparation method of the present application is made by the thermoelectric yarn with specific PN interval structure, and the thermoelectric fabric that can effectively collect human thermal energy is made.

Description

Technical Field

[0001] This invention belongs to the field of thermoelectric fabric technology, and particularly relates to a thermoelectric fabric and its preparation method. Background Technology

[0002] Smart textiles can provide more effective healthcare and other functions by collecting human biosignals and detecting the surrounding environment, greatly improving people's quality of life. However, most wearable electronic devices currently use traditional batteries for power, which are bulky and inconvenient to use, limiting their application. Wearable thermoelectric generators (TEGs), on the other hand, utilize temperature differences (ΔT) to convert heat energy into direct current, effectively converting human body heat energy into electrical energy and thus solving the shortcomings of traditional batteries.

[0003] Since the human body continuously radiates heat, collecting this heat and using it to power thermoelectric generators for wearable electronic devices has become a new option for wearable energy harvesting. Textiles are indispensable materials in daily life, and combining thermoelectric generators with textiles allows for effective energy harvesting by utilizing the temperature difference (ΔT) between the human body and the environment. Furthermore, traditional thermoelectric generators require multiple pairs of materials with P-type and N-type semiconductor properties connected in series to form an alternating PNPN-…-PNPN structure. Therefore, alternately integrating P and N materials on a single yarn and further fabricating it into thermoelectric fabric has become one of the best options currently available, balancing flexibility and output performance.

[0004] Existing methods for preparing PN-spaced composite yarns typically involve segmented deposition of P and N thermoelectric materials using atomic layer deposition (ALD) and magnetron sputtering, which are difficult and costly. Furthermore, commonly used PN thermoelectric materials have certain toxicity and are made from scarce raw materials (such as bismuth antimonide-based thermoelectric materials), hindering large-scale adoption. Since the P and N properties of carbon nanotubes can be adjusted using simple solution processing, researchers have prepared thermoelectric yarns with PN-spaced structures based on carbon nanotube fibers, achieving excellent thermoelectric performance and effectively collecting heat energy from the human body. However, the production of such pure carbon nanotube fibers remains complex, cumbersome, and costly. Moreover, due to the limited thickness of carbon nanotube fibers (a single carbon nanotube fiber is typically less than 100 micrometers), their mechanical strength is insufficient to meet the requirements of traditional textile fibers, often requiring multiple carbon nanotube fibers to be wound and twisted, further increasing costs. While carbon nanotube-based thermoelectric materials are abundant and their PN-spaced structure can be controlled through solution processing, the limited production of pure carbon nanotube fibers with high thermoelectric performance results in their high price due to the nascent stage of their preparation.

[0005] Traditional carbon nanotube composite yarns, prepared using a single type of carbon nanotube powder as raw material, cannot simultaneously achieve high Seebeck coefficient and high electrical conductivity due to the different types of carbon nanotubes. Creating a simple and scalable method to produce cost-effective, high-strength thermoelectric yarns is crucial. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the problems of high raw material cost and poor mechanical strength of thermoelectric yarn in the prior art.

[0007] To address the aforementioned technical problems, this invention provides a thermoelectric fabric and its preparation method.

[0008] The first objective of this invention is to provide a method for preparing thermoelectric fabrics, comprising the following steps:

[0009] S1. The matrix yarn is impregnated with single-walled carbon nanotube aqueous slurry and multi-walled carbon nanotube / aqueous polyurethane composite slurry by impregnation coating method, and then dried to obtain carbon nanotube composite yarn.

[0010] S2. The carbon nanotube composite yarn described in S1 is wound onto a template, and silver paste is coated at the nodes on both sides. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) solution and polyethyleneimine (PEI) alcohol solution are coated on the surface of the carbon nanotube composite yarn that is not coated with silver paste, and then dried to obtain a thermoelectric yarn with a PN spacer structure.

[0011] S3. The thermoelectric yarn with PN spacer structure described in S2 is implanted into the three-dimensional warp-knitted spacer fabric through an embroidery process to obtain the thermoelectric fabric.

[0012] In one embodiment of the present invention, in S1, the material of the base yarn is one or more of cotton, polyester, silk and viscose.

[0013] In one embodiment of the present invention, in S1, the concentration of the single-walled carbon nanotube aqueous slurry is 0.05wt%-0.5wt%.

[0014] In one embodiment of the present invention, in S1, the multi-walled carbon nanotube / polyurethane composite slurry is obtained by mixing multi-walled carbon nanotube aqueous slurry and aqueous polyurethane solution at a mass ratio of 1-4:1; the concentration of multi-walled carbon nanotube aqueous slurry is 2wt%-15wt%, and the concentration of aqueous polyurethane solution is 10wt%-30wt%.

[0015] In one embodiment of the present invention, in S1, the immersion time is 20 min to 30 min.

[0016] In one embodiment of the present invention, in S2, the concentration of the poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) solution is 1wt%-1.5wt%.

[0017] In one embodiment of the present invention, before S1, the matrix yarn is further subjected to pretreatment. The pretreatment involves ultrasonically cleaning the matrix yarn in ethanol and water, respectively, to ensure that impurities in the matrix yarn are cleaned and improved, and to loosen the matrix yarn through ultrasonic operation, which facilitates the subsequent infiltration of carbon nanotube materials.

[0018] In one embodiment of the present invention, in S2, the concentration of the polyethyleneimine solution is 5wt%-10wt%.

[0019] In one embodiment of the invention, in S2, the silver coating can prevent over-seepage of the subsequent treatment solution and serve as a marker for PN nodes during the embroidery process.

[0020] In one embodiment of the present invention, the drying temperature in both S1 and S2 is 45°C-55°C.

[0021] In one embodiment of the present invention, in S3, the thickness of the three-dimensional warp-knitted spacer fabric is 0.5cm-1cm.

[0022] A second objective of this invention is to provide a thermoelectric fabric prepared by the method described above.

[0023] In one embodiment of the present invention, the thermoelectric fabric can utilize the temperature difference between the human body surface temperature and the outer surface temperature of the fabric for thermoelectric conversion.

[0024] The technical solution of the present invention has the following advantages compared with the prior art:

[0025] (1) The preparation method of the present invention prepares carbon nanotube composite yarn with high thermoelectric properties through an impregnation coating method. Carbon nanotubes can be classified into single-walled, double-walled, and multi-walled types according to the number of walls. Carbon nanotube composite yarns made from single-walled carbon nanotubes have a high Seebeck coefficient (S, a physical quantity characterizing the voltage generated per degree Celsius) but low electrical conductivity (σ, a physical quantity measuring the strength of electrical conductivity), while carbon nanotube composite yarns supported by multi-walled carbon nanotubes have a low Seebeck coefficient but high electrical conductivity. Therefore, by using a two-stage coating method, single-walled carbon nanotube slurry and multi-walled carbon nanotube slurry are coated respectively, thereby producing a yarn with a high power factor (PF, a physical quantity used to measure the amount of electrical energy generated, PF = S). 2 A carbon nanotube composite yarn (σ) was developed. A certain amount of waterborne polyurethane was added during the coating process of multi-walled carbon nanotubes, effectively improving the stability of the carbon nanotubes in the composite yarn.

[0026] (2) The preparation method described in this invention can rapidly and massively prepare carbon nanotube composite yarns with high thermoelectric properties and high strength through an impregnation coating method. Specifically, by coordinating the use of single-walled and multi-walled carbon nanotubes, the thermoelectric collection effect of the composite yarn is effectively improved; the introduction of a small amount of waterborne polyurethane increases the mechanical strength of the composite yarn (approaching that of the initial matrix yarn, with almost no attenuation of mechanical properties) and effectively solves the problem of carbon nanotubes not being effectively attached to the composite yarn.

[0027] (3) The preparation method described in this invention utilizes the adjustable thermoelectric properties of carbon nanotubes. Combined with a solution treatment method (PEI alcohol solution), the p-type thermoelectric properties of carbon nanotubes can be converted to n-type thermoelectric properties. PEDOT:PSS solution can enhance the p-type thermoelectric properties of the carbon nanotube composite yarn. A thermoelectric yarn with a PN spacer structure is prepared by intermittently coating PEDOT:PSS solution and PEI alcohol solution using an intermittent coating method. Thermoelectric yarns with a PN spacer structure are rapidly and accurately prepared by coating materials using a simple template intermittent coating method.

[0028] (4) The preparation method described in this invention uses embroidery to insert the thermoelectric yarn into a three-dimensional spacer fabric to make a thermoelectric fabric.

[0029] (5) The preparation method described in this invention uses thermoelectric yarn with a specific PN spacer structure to make a thermoelectric fabric that can effectively collect human body heat energy. Attached Figure Description

[0030] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0031] Figure 1 This is a flowchart illustrating the preparation process of the carbon nanotube composite yarn of the present invention.

[0032] Figure 2 This is a flowchart illustrating the preparation process of the thermoelectric yarn with a PN spacer structure according to the present invention.

[0033] Figure 3 This is a structural diagram of the thermoelectric fabric of the present invention; wherein, a) is a schematic diagram and b) is a physical object diagram.

[0034] Figure 4 The images shown are scanning electron microscope images of the materials in Test Example 1 of the present invention; where a) is after coating with a single-walled carbon nanotube aqueous slurry, and b) is after coating with a multi-walled carbon nanotube / aqueous polyurethane composite slurry.

[0035] Figure 5The figures show the thermoelectric properties and actual wearability of the material in Test Example 2 of this invention; where a) is the thermoelectric properties of the thermoelectric yarn before and after modification, and b) is the actual voltage output of the thermoelectric fabric worn on the human body.

[0036] Figure 6 This refers to the mechanical strength of the material in Test Example 3 of this invention. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0038] In this invention, unless otherwise stated, the single-walled carbon nanotube aqueous slurry used in the following examples was purchased from Zhongke Times Nano Energy Co., Ltd., and the concentration was 0.2 wt%.

[0039] In this invention, unless otherwise stated, the multi-walled carbon nanotube / aqueous polyurethane composite slurry used in the following examples is obtained by mixing multi-walled carbon nanotube aqueous slurry and aqueous polyurethane solution at a mass ratio of 1-4:1. The multi-walled carbon nanotube aqueous slurry was purchased from Chengdu Times Nano Co., Ltd., with a concentration of 13 wt%; the aqueous polyurethane solution was purchased from BGI Chemical Group Co., Ltd., with a concentration of 30 wt%.

[0040] In this invention, unless otherwise stated, the PEDOT:PSS aqueous solution used in the following examples was purchased from Heraeus Group Inc. and had a concentration of 1.2 wt%.

[0041] In this invention, unless otherwise stated, the PEI alcohol solution used in the following examples was prepared with anhydrous ethanol, and PEI (Mw=600) was purchased from Shanghai Titan Technology Co., Ltd.

[0042] Example 1

[0043] A thermoelectric fabric and its preparation method, specifically including the following steps:

[0044] S1, such as Figure 1 As shown, the preparation of carbon nanotube composite yarn

[0045] S11. Clean the pure cotton yarn, which is about 3m long and 40tex fineness, with ethanol and water three times, each time for 20 minutes.

[0046] S12. Immerse the cleaned pure cotton yarn in a water-based slurry containing single-walled carbon nanotubes. After ultrasonic immersion in a water bath for 30 minutes, dry it in a 50°C oven. Repeat this operation 3 times to ensure the adhesion of single-walled carbon nanotubes.

[0047] S13. The yarn is immersed in multi-walled carbon nanotube / waterborne polyurethane composite slurry (the mass ratio of multi-walled carbon nanotube waterborne slurry to waterborne polyurethane solution is 4:1) for 30 minutes and dried in an oven at 50°C to obtain carbon nanotube composite yarn.

[0048] S2, such as Figure 2 As shown, the fabrication of thermoelectric yarn with PN spacer structure

[0049] S21. Tightly bind the carbon nanotube composite yarn onto a polytetrafluoroethylene template with a width and thickness of 1cm × 0.5cm; brush conductive silver paste onto the two short sides (0.5cm) as electrode markings.

[0050] S22. Immerse one long side in a PEI alcohol solution (5wt%) to achieve N-type modification of this part; immerse the other long side in a PEDOT:PSS aqueous solution to achieve P-type modification of this part; place the modified composite yarn in a 50℃ oven to dry, remove the template, and obtain a thermoelectric yarn with a PN spacer structure.

[0051] S3, such as Figure 3 As shown, the preparation of thermoelectric fabrics

[0052] Thermoelectric yarns with a PN spacer structure are embedded into a 1cm thick three-dimensional warp-knitted spacer fabric through an embroidery process. Thermoelectric yarns coated with silver paste are located on the upper and lower surfaces of the spacer fabric to obtain the thermoelectric fabric.

[0053] Example 2

[0054] A thermoelectric fabric and its preparation method, specifically including the following steps:

[0055] Preparation of S1 carbon nanotube composite yarn

[0056] S11. Clean the pure cotton yarn, which is about 2m long and 30tex fine, with ethanol and water three times, each time for 20 minutes.

[0057] S12. Immerse the cleaned pure cotton yarn in a water-based slurry containing single-walled carbon nanotubes. After ultrasonic immersion in a water bath for 30 minutes, dry it in a 50°C oven. Repeat this operation 3 times to ensure the adhesion of single-walled carbon nanotubes.

[0058] S13. The yarn is immersed in multi-walled carbon nanotube / waterborne polyurethane composite slurry (the mass ratio of multi-walled carbon nanotube waterborne slurry to waterborne polyurethane solution is 2:1) for 30 minutes and dried in an oven at 50°C to obtain carbon nanotube composite yarn.

[0059] S2. Preparation of thermoelectric yarns with PN spacer structure

[0060] S21. Tightly bind the carbon nanotube composite yarn onto a polytetrafluoroethylene template with dimensions of 0.8cm × 0.5cm; brush conductive silver paste onto the two short sides (0.5cm) as electrode markings.

[0061] S22. Immerse one long side in a PEI alcohol solution (10wt%) to achieve N-type modification of this part; immerse the other long side in a PEDOT:PSS aqueous solution to achieve P-type modification of this part; place the modified composite yarn in a 50℃ oven to dry, remove the template, and obtain a thermoelectric yarn with a PN spacer structure.

[0062] S3. Preparation of thermoelectric fabrics

[0063] Thermoelectric yarns with a PN spacer structure are embedded into a 0.8cm thick three-dimensional warp-knitted spacer fabric through an embroidery process. Thermoelectric yarns coated with silver paste are located on the upper and lower surfaces of the spacer fabric, respectively, to obtain the thermoelectric fabric.

[0064] Example 3

[0065] A thermoelectric fabric and its preparation method, specifically including the following steps:

[0066] Preparation of S1 carbon nanotube composite yarn

[0067] S11. Clean a piece of pure cotton yarn, about 2.5m long and 35tex fineness, three times with ultrasonic cleaning in ethanol and water, 20 minutes each time.

[0068] S12. Immerse the cleaned pure cotton yarn in a water-based slurry containing single-walled carbon nanotubes. After ultrasonic immersion in a water bath for 30 minutes, dry it in a 50°C oven. Repeat this operation 3 times to ensure the adhesion of single-walled carbon nanotubes.

[0069] S13. The yarn is immersed in multi-walled carbon nanotube / waterborne polyurethane composite slurry (the mass ratio of multi-walled carbon nanotube waterborne slurry to waterborne polyurethane solution is 1:1) for 30 minutes and dried in an oven at 50°C to obtain carbon nanotube composite yarn.

[0070] S2. Preparation of thermoelectric yarns with PN spacer structure

[0071] S21. Tightly bind the carbon nanotube composite yarn onto a polytetrafluoroethylene template with dimensions of 0.5cm × 0.2cm; brush conductive silver paste onto the two short sides (0.2cm) as electrode markings.

[0072] S22. Immerse one long side in a PEI alcohol solution (8wt%) to achieve N-type modification of this part; immerse the other long side in a PEDOT:PSS aqueous solution to achieve P-type modification of this part; place the modified composite yarn in a 50℃ oven to dry, remove the template, and obtain a thermoelectric yarn with a PN spacer structure.

[0073] S3. Preparation of thermoelectric fabrics

[0074] Thermoelectric yarns with a PN spacer structure are embedded into a 0.5cm thick three-dimensional warp-knitted spacer fabric through an embroidery process. Thermoelectric yarns coated with silver paste are located on the upper and lower surfaces of the spacer fabric, respectively, to obtain the thermoelectric fabric.

[0075] Comparative Example 1

[0076] The process is basically the same as in Example 1, except that a single-walled carbon nanotube aqueous slurry is not used for treatment. The resulting yarn has a low Seebeck coefficient (18 μV / K), making it difficult to generate a high voltage output.

[0077] Comparative Example 2

[0078] The process is basically the same as in Example 1, except that multi-walled carbon nanotube / waterborne polyurethane composite slurry is not used. The resulting yarn has a low electrical conductivity (0.5 S / m), which affects the final output power.

[0079] Test Example 1

[0080] Based on Example 1, yarns coated with single-walled carbon nanotube aqueous slurry and yarns coated with multi-walled carbon nanotube / aqueous polyurethane composite slurry were characterized, and the results are as follows: Figure 4 As shown. From Figure 4 It can be seen that single-walled carbon nanotubes are largely attached to the fibers of cotton yarn, while multi-walled carbon nanotubes / waterborne polyurethane composites are tightly wrapped on the surface of the yarn, greatly increasing the adhesion stability of carbon nanotubes.

[0081] Test Example 2

[0082] Based on Example 1, the wearability of the thermoelectric yarn and thermoelectric fabric before and after modification was tested, and the results are as follows: Figure 5 As shown. From Figure 5 It can be seen that PEDOT:PSS aqueous solution treatment can effectively improve the thermoelectric properties of the composite yarn, while PEI alcohol solution treatment can make the composite yarn exhibit N-type thermoelectric properties. The thermoelectric fabric can generate a voltage output of 8.3mV when worn on the arm.

[0083] Test Example 3

[0084] Based on Example 1, the mechanical strength of pure cotton yarn and yarns coated with single-walled carbon nanotube waterborne and multi-walled carbon nanotube / waterborne polyurethane composite slurries were tested, and the results are shown in Figure 6. Figure 6 It can be seen that the extensive adhesion of carbon nanotubes reduces the cohesion of cotton fibers in pure cotton yarn, thus lowering the mechanical strength of the composite yarn. However, after coating with multi-walled carbon nanotubes / waterborne polyurethane, the waterborne polyurethane acts as an adhesive, greatly improving the strength of the composite yarn to a level comparable to that of pure cotton yarn.

[0085] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a thermoelectric fabric, characterized in that, Includes the following steps, S1. The matrix yarn is sequentially immersed in a single-walled carbon nanotube aqueous slurry and a multi-walled carbon nanotube / aqueous polyurethane composite slurry by an impregnation coating method, and then dried to obtain a carbon nanotube composite yarn. S2. The carbon nanotube composite yarn described in S1 is wound onto a template, and silver paste is applied to the nodes on both sides. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid solution and polyethyleneimine alcohol solution are respectively applied to the carbon nanotube composite yarn surfaces on opposite sides of the template where silver paste is not applied. After drying, a thermoelectric yarn with a PN spacer structure is obtained. S3. The thermoelectric yarn with PN spacer structure described in S2 is implanted into the three-dimensional warp-knitted spacer fabric through an embroidery process to obtain the thermoelectric fabric.

2. The method for preparing thermoelectric fabric according to claim 1, characterized in that, In S1, the material of the base yarn is one or more of cotton, polyester, silk and viscose.

3. The method for preparing thermoelectric fabric according to claim 1, characterized in that, In S1, the concentration of the single-walled carbon nanotube aqueous slurry is 0.05wt%-0.5wt%.

4. The method for preparing thermoelectric fabric according to claim 1, characterized in that, In S1, the multi-walled carbon nanotube / polyurethane composite slurry is obtained by mixing multi-walled carbon nanotube aqueous slurry and aqueous polyurethane solution at a mass ratio of 1-4:1; the concentration of multi-walled carbon nanotube aqueous slurry is 2wt%-15wt%, and the concentration of aqueous polyurethane solution is 10wt%-30wt%.

5. The method for preparing thermoelectric fabric according to claim 1, characterized in that, In S1, the immersion time is 20-30 minutes.

6. The method for preparing thermoelectric fabric according to claim 1, characterized in that, In S2, the concentration of the poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid solution is 1wt%-1.5wt%.

7. The method for preparing thermoelectric fabric according to claim 1, characterized in that, In S2, the concentration of the polyethyleneimine solution is 5wt%-10wt%.

8. The method for preparing thermoelectric fabric according to claim 1, characterized in that, In both S1 and S2, the drying temperature is 45℃-55℃.

9. The method for preparing thermoelectric fabric according to claim 1, characterized in that, In S3, the thickness of the three-dimensional warp-knitted spacer fabric is 0.5cm-1cm.

10. The thermoelectric fabric prepared by the method according to any one of claims 1-9.

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