Flexible triboelectric nanogenerator based on superhydrophobic film and preparation method thereof

Abstract

This invention discloses a flexible triboelectric nanogenerator (TENG) based on a superhydrophobic thin film, comprising a positive friction layer and a negative friction layer. The positive and negative friction layers are made of flexible thin films as the electrode base materials, and both electrodes are based on flexible materials. A gap exists between the positive and negative friction layers, and the edges of the two friction layers are electrically connected. At the connection points, the two friction layers can contact each other to generate positive and negative static charges, and electrons flow between the two electrode layers to form alternating current. By using flexible thin films as the electrode base materials for the positive and negative friction layers, this invention achieves a high dielectric constant while maintaining the flexibility and stretchability of the polymer matrix, effectively improving the output power of the TENG and resulting in better electrical performance.

Description

Technical Field

[0001] This invention belongs to the field of triboelectric nanogenerator technology, and relates to a flexible triboelectric nanogenerator based on a superhydrophobic thin film, as well as a method for preparing the aforementioned flexible triboelectric nanogenerator based on a superhydrophobic thin film. Background Technology

[0002] Triboelectric nanogenerators (TENGs) are the smallest existing generators that convert mechanical energy into electrical energy. Compared with piezoelectric nanogenerators (PENGs), TENGs have advantages such as high output, high efficiency, low cost, simple structural design, excellent stability, and environmental friendliness. Based on the coupling mechanism of triboelectric effect and electrostatic induction, when two friction materials with different polarities come into contact, charges are generated at the contact surface. When the positive and negative electrodes are separated, a potential difference is generated, thereby forming a current output of the external circuit.

[0003] TENG (Tension Engine) not only effectively converts mechanical energy into electrical energy, but can also be used as a self-powered sensor in fields such as human motion detection, healthcare, infrastructure monitoring, and security. Meanwhile, flexible electronic devices have garnered significant attention in recent years as one of the future directions of electronic device development. Compared to traditional electronic components, flexible electronic devices are lightweight, thin, flexible, and bendable, exhibiting high flexibility, stretchability, and bendability. Consequently, concepts such as wearable devices, implantable medical devices, electronic skin, and smart electronic fabrics have been continuously proposed, forming part of the blueprint for future human life. To meet the requirements of flexible electronic devices for being lightweight, thin, transparent, flexible, stretchable, insulating, and corrosion-resistant, common flexible materials include: polyvinyl alcohol (PVA), polydimethylsiloxane (PDMS), polyester (PET), polyimide (PI), polyacrylamide (PAM), and textile materials. These materials all possess advantages such as easy availability, chemical stability, transparency, and good thermal stability.

[0004] Flexible triboelectric nanogenerators (TENGs) utilize triboelectric effect and electrostatic induction to convert the mechanical energy of human movement into electrical energy. However, existing TENGs have the following problems: 1. The electronegativity difference between the positive and negative triboelectric electrode materials of existing TENGs is relatively small, resulting in low output power; 2. Due to the low conductivity, poor mechanical and biocompatibility, and slow response to external stimuli of flexible materials, the high toughness of flexible materials cannot be guaranteed under the condition of output electrical performance, which greatly limits practical applications; 3. Most current TENGs do not have tight encapsulation and are often in direct contact with the external environment, making their output performance highly susceptible to the influence of external humidity or dust contamination. Summary of the Invention

[0005] One objective of this invention is to provide a flexible triboelectric nanogenerator based on a superhydrophobic film, which solves the problems of low output performance and susceptibility to external humidity or dust contamination in existing flexible TENGs.

[0006] Another object of the present invention is to provide a method for preparing a flexible triboelectric nanogenerator based on a superhydrophobic thin film.

[0007] One technical solution adopted in this invention is a flexible triboelectric nanogenerator based on a superhydrophobic thin film, comprising a positive friction layer and a negative friction layer. The positive and negative friction layers are made of flexible thin film as the electrode base material. Both the positive and negative friction electrodes are based on flexible materials. There is a gap between the positive and negative friction layers. The edges of the two friction layers are electrically connected. The two friction layers can contact each other at the connection point to generate positive and negative static charges. Electrons flow between the two electrode layers to form alternating current.

[0008] The invention is further characterized in that,

[0009] The negative friction layer is a PDMS / PVDF-HFP / PAM composite film with a uniform cubic microstructure. The cubic microstructure negative friction layer film is fabricated by using micro-nano cubic film tools.

[0010] The positive friction layer is a flexible superhydrophobic composite film of PAM / CITf / MWCNT / FCNT / RGO, and the positive friction electrode material is coated on the surface of PAM hydrogel. The components of the flexible superhydrophobic composite film of the positive friction layer include a composite film formed by a mixture of CITf, MWCNT, FCNT and RGO nanoparticles.

[0011] Another technical solution adopted in this invention is a method for preparing a flexible triboelectric nanogenerator based on a superhydrophobic thin film. The preparation of the aforementioned flexible triboelectric nanogenerator based on a superhydrophobic thin film is carried out according to the following steps:

[0012] Step 1: Prepare PDMS / PVDF-HFP / PAM composite film;

[0013] Step 2: Prepare a flexible superhydrophobic composite film of PAM / CITf / MWCNT / FCNT / RGO;

[0014] Step 3: Assemble the components.

[0015] The invention is further characterized in that,

[0016] Step 1 is implemented in the following steps:

[0017] Step 1.1: Add polyacrylamide nanoparticles and PVDF-HFP nanoparticles to a chloroform solution, stir and disperse evenly to obtain a chloroform mixture;

[0018] The mass percentage of PAM nanoparticles in the solution was controlled at 10%, and the mass percentage of PVDF-HFP nanoparticles was controlled at 5%; the mixture was stirred at 40–50 rpm for 1–2 hours.

[0019] Step 1.2: Stir the chloroform mixture obtained in Step 1.1 continuously until fully mixed, and then sonicate for 0.5 to 1 hour to evaporate the chloroform in the mixture to obtain the mixed matrix;

[0020] Step 1.3: Add the curing agent and PDMS to the mixed matrix in Step 1.2 at a weight ratio of 1:10. Sonicate the mixture of PAM, PVDF-HFP and PDMS for 15 minutes to remove air bubbles. Transfer the mixture into the cavity of a polytetrafluoroethylene membrane with a uniform cubic microstructure to obtain a composite membrane. Control the thickness of the composite membrane within the range of 135-155 μm.

[0021] Step 1.4: Place the composite film in an oven at 80°C for 2 hours to cure, and then cure at room temperature for 24 hours to obtain the PDMS / PVDF-HFP / PAM composite film.

[0022] Step 2 is implemented in the following steps:

[0023] Step 2.1: Prepare RGO;

[0024] Step 2.2: Prepare a composite film of PAM / CITf / MWCNT / FCNT / RGO.

[0025] Step 2.1 is implemented according to the following steps:

[0026] Step 2.1.1: Place graphene oxide in deionized water and sonicate for 2 hours to obtain a GO dispersion solution;

[0027] Step 2.1.2: Select L-ascorbic acid as a reducing agent, add L-AA to the dispersion solution of GO and stir thoroughly. Filter and dry the RGO on a polytetrafluoroethylene membrane to obtain RGO on the PTFE membrane.

[0028] Step 2.2 is implemented according to the following steps:

[0029] Step 2.2.1: Add polyacrylamide (PAM), cellulose (CITf), multi-walled carbon nanotubes (MWCNT), fluorinated carbon nanotubes (FCNT), and the RGO nanoparticles prepared in step 2.1 to the chloroform solution, stir to disperse evenly, and then evaporate the chloroform completely after ultrasonic treatment.

[0030] Step 2.2.2: After the hydrolysis, polycondensation and aging process, a stable PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected on the polyPTFE membrane using a vacuum filtration device. The thickness of the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is controlled to be 125-135μm. The PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected by peeling it off with a polytetrafluoroethylene scraper.

[0031] Step 3 specifically involves:

[0032] Step 3.1: Cut the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in Step 1 and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in Step 2 into 4×4cm sections. 2 ;

[0033] Step 3.2: Use the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in step 1 as the negative friction layer (3), and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in step 2 as the positive friction layer (2). Connect the two sides of the cut PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film and the PDMS / PVDF-HFP / PAM composite film.

[0034] Step 3.3: Copper tape is pasted on the negative friction layer (3) as copper electrode (1), and copper tape is pasted on the positive friction layer (2) as copper electrode (1). The positive friction layer (2) and the negative friction layer (3) are squeezed into a U-shape, and the two sides are fixed on the mover and stator of the linear motor respectively. The position, amplitude and speed of the motor mover are controlled by adjusting the drive controller, so that the positive and negative friction layers of the device can periodically contact and separate.

[0035] Step 3.4: Connect the copper electrode (1) of the device to the test terminal of the meter with a wire to measure the output electrical performance of the device. The assembly of TENG is now complete, and the measurement can be performed next.

[0036] In step 2.2.1, the mass percentage of PAM is controlled at 30%, the mass percentage of cellulose is 25%, and the mass percentages of RGO, MWCNT, and FCNT are all 15%.

[0037] The beneficial effects of the present invention are that it also has the following advantages:

[0038] 1. Both the positive and negative electrodes of this invention adopt a composite friction layer. The high dielectric constant nanocomposite material enhances the output electrical characteristics of the triboelectric nanogenerator. The charge trapping ability usually increases with the increase of the dielectric constant of the material, thereby increasing the dielectric constant of the friction layer and increasing the surface charge density.

[0039] 2. Compared with traditional metal electrodes, PDMS and PVDF-HFP are introduced into the hydrogel in the negative tribological electrode to improve the electronegativity of the hydrogel; PAM is used as a substrate in the positive tribological material to construct a superhydrophobic composite film to enhance the overall mechanical and biocompatibility, so as to realize a multifunctional flexible tribological hydrogel composite film.

[0040] 3. The flexible superhydrophobic structure can suppress the formation of water films on the surface in high humidity environments, and the self-cleaning property of the flexible superhydrophobic surface prevents TENG from being contaminated by dust and other environmental pollutants. The fiber nano-aqueous coating is biodegradable, low-pollution, and widely available, possessing superior strength and flexibility. The flexible superhydrophobic friction layer material of this invention is simple and reliable to develop, and has significant implications for widespread application. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the PDMS / PVDF-HFP / PAM composite membrane structure with uniform cubic microstructure in the negative friction layer of the present invention;

[0042] Figure 2 This is a schematic diagram of the performance testing connection structure of the flexible triboelectric nanogenerator based on superhydrophobic thin film of the present invention.

[0043] In the figure, 1. Copper electrode, 2. Positive friction layer, 3. Negative friction layer. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0045] The flexible triboelectric nanogenerator based on a superhydrophobic thin film prepared in this invention has the following structure: Figure 1 As shown, it includes a positive friction layer 2 and a negative friction layer 3. The positive and negative friction layers 2 are made of flexible thin film as the electrode base material, which obtains a high dielectric constant while ensuring the flexibility and stretchability of the polymer matrix. Both the positive and negative friction electrodes are based on flexible materials. There is a gap between the positive friction layer 2 and the negative friction layer 3. The edges of the two friction layers are electrically connected. At the connection point, the two friction layers can contact each other to generate positive and negative static charges. Electrons flow between the two electrode layers to form alternating current.

[0046] The negative friction layer 3 is a PDMS / PVDF-HFP / PAM composite film with a uniform cubic microstructure, which enhances the electronegativity of the negative friction layer 3. The cubic microstructure negative friction layer film is fabricated using micro / nano cubic film tools, such as... Figure 1As shown, a good triboelectric structure lays the foundation for the efficient triboelectric charging of PDMS films. By changing the contact structure of the negative triboelectric electrode material, the coefficient of friction is increased, thereby increasing the charge density and storage space of the negative triboelectric material film, so as to achieve higher electrical performance output of TENG.

[0047] Compared with pure PVDF, PVDF-HFP copolymerizes with vinylidene fluoride (VDF) by introducing hexafluoropropylene (HFP) groups onto the VDF groups, which effectively increases the fluorine content in the polymer. PVDF-HFP has a strong ability to acquire electrons from other materials and has an ideal piezoelectric constant and a high electromechanical coupling factor. Adding PVDF-HFP composite fibers to PDMS, the base material of the negative triboelectric electrode, effectively improves the output performance of TENG.

[0048] The positive friction layer 2 is a flexible superhydrophobic composite film of PAM / CITf / MWCNT / FCNT / RGO, with the positive friction electrode material coated onto the PAM hydrogel surface. The flexible superhydrophobic composite film of the positive friction layer 2 comprises a composite film formed by mixed nanoparticles of CITf, MWCNT, FCNT, and RGO, effectively preventing contamination of the device by dust and moisture from the environment. The modified PVDF-HFP material improves the TENG power, while the PAM hydrogel enhances the tensile strength, self-healing properties, and conductivity of the negative friction layer material.

[0049] The present invention discloses a method for fabricating a flexible triboelectric nanogenerator based on a superhydrophobic thin film, which is implemented according to the following steps:

[0050] Step 1: Prepare PDMS / PVDF-HFP / PAM composite film, specifically by following these steps:

[0051] Step 1.1: Add polyacrylamide (PAM) nanoparticles and PVDF-HFP nanoparticles to a chloroform solution, stir and disperse evenly to obtain a chloroform mixture; control the mass percentage of PAM nanoparticles in the solution to be 10%, and control the mass percentage of PVDF-HFP nanoparticles to be 5%; stir at 40-50 rpm for 1-2 hours.

[0052] Step 1.2: Stir the chloroform mixture obtained in Step 1.1 continuously until fully mixed, and then sonicate for 0.5 to 1 hour to evaporate the chloroform in the mixture to obtain the mixed matrix;

[0053] Step 1.3: Add the curing agent and PDMS to the mixed matrix in Step 1.2 at a weight ratio of 1:10. Sonicate the mixture of PAM, PVDF-HFP and PDMS for 15 minutes to remove air bubbles. Transfer the mixture into the cavity of a polytetrafluoroethylene (PTFE) membrane with a uniform cubic microstructure to obtain a composite membrane. Control the thickness of the composite membrane to be in the range of 135-155 μm; the thickness of the cubic microstructure is 5 μm.

[0054] Step 1.4: Place the composite film in an oven at 80°C for 2 hours to cure, and then cure at room temperature for 24 hours to obtain the PDMS / PVDF-HFP / PAM composite film.

[0055] Step 2: Prepare PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic films, specifically following these steps:

[0056] Step 2.1: Prepare RGO nanoparticles;

[0057] Step 2.1.1: Place graphene oxide (GO) in deionized water and sonicate for 2 hours to obtain a GO dispersion solution. Since deionized water has a strong ion absorption capacity, clean and uniformly dispersed GO can be obtained after sonication in deionized water.

[0058] Step 2.1.2: Select L-ascorbic acid (L-AA) as a reducing agent, add L-AA to the GO dispersion solution and stir thoroughly. Filter and dry the RGO on a polytetrafluoroethylene (PTFE) membrane to obtain RGO on the PTFE membrane. The RGO nanoparticles have an outer diameter of 20 nm and a length of 15 μm.

[0059] Step 2.2: Prepare PAM / CITf / MWCNT / FCNT / RGO composite film;

[0060] Step 2.2.1: Add polyacrylamide (PAM), cellulose (CITf), multi-walled carbon nanotubes (MWCNT), fluorinated carbon nanotubes (FCNT), and RGO prepared in step 2.1 to the chloroform solution, respectively. Control the mass percentage of PAM to 30%, the mass percentage of cellulose to 25%, and the mass percentages of RGO, MWCNT, and FCNT to 15%. Stir to disperse evenly, and then evaporate the chloroform completely after ultrasonic treatment.

[0061] Among them, the FCNT nanoparticles have an outer diameter of 25 nm and a length of 20 μm, and the hydrophobic cationic cellulose derivative effectively disperses MWCNT; the synergistic effect of the cationic cellulose derivative and MWCNT effectively disperses RGO.

[0062] Step 2.2.2: After the hydrolysis, polycondensation, and aging process, a stable PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected on the polyPTFE membrane using a vacuum filtration device. The thickness of the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is controlled to be 125-135 μm. The PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film is collected by peeling it off with a polytetrafluoroethylene (PTFE) scraper.

[0063] Due to the various nanostructures with different shapes and sizes in the dispersion and the adhesive effect of cellulose derivatives, flexible superhydrophobic films with self-similar micro-nano structures spontaneously form from the inside out.

[0064] Step 3: Assemble the components;

[0065] Step 3.1: Cut the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in Step 1 and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in Step 2 into 4×4cm sections. 2 ;

[0066] Step 3.2: Use the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in Step 1 as negative friction layer 3, and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in Step 2 as positive friction layer 2. Connect the two sides of the cut PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film and the PDMS / PVDF-HFP / PAM composite film.

[0067] Step 3.3: Copper tape is adhered to the negative friction layer 3 as copper electrode 1, and simultaneously, copper tape is adhered to the positive friction layer 2 as copper electrode 1. The positive friction layer 2 and the negative friction layer 3 are pressed together into a U-shape, as shown below. Figure 2 As shown, the positive friction layer 2 and the negative friction layer 3 are fixed on the mover and stator of the linear motor respectively. The position, amplitude and speed of the motor mover are controlled by adjusting the drive controller, so that the positive and negative friction layers of the device can periodically contact and separate.

[0068] Step 3.4: Connect the copper electrode 1 of the device to the test terminal of the meter with a wire to measure the output electrical performance of the device. The assembly of TENG is now complete, and the measurement can be performed next.

[0069] Example 1

[0070] Example 1 of this invention describes a method for preparing a flexible triboelectric nanogenerator based on a superhydrophobic thin film, which is implemented according to the following steps:

[0071] Step 1: Prepare PDMS / PVDF-HFP / PAM composite film, specifically by following these steps:

[0072] Step 1.1: Add polyacrylamide nanoparticles and PVDF-HFP nanoparticles to a chloroform solution and stir to disperse them evenly to obtain a chloroform mixture; control the mass percentage of PAM nanoparticles in the solution to be 10% and the mass percentage of PVDF-HFP nanoparticles to be 5%; stir at 40-50 rpm for 1-2 hours.

[0073] Step 1.2: Stir the chloroform mixture obtained in Step 1.1 continuously until fully mixed, and then sonicate for 0.5 to 1 hour to evaporate the chloroform in the mixture to obtain the mixed matrix;

[0074] Step 1.3: Add the curing agent and PDMS to the mixed matrix in Step 1.2 at a weight ratio of 1:10. Sonicate the mixture of PAM, PVDF-HFP and PDMS for 15 minutes to remove air bubbles. Transfer the mixture into the cavity of a polytetrafluoroethylene membrane with a uniform cubic microstructure to obtain a composite membrane. Control the thickness of the composite membrane within the range of 135-155 μm.

[0075] Step 1.4: Place the composite film in an oven at 80°C for 2 hours to cure, and then cure at room temperature for 24 hours to obtain the PDMS / PVDF-HFP / PAM composite film.

[0076] Step 2: Prepare PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic films, specifically following these steps:

[0077] Step 2.1: Prepare RGO;

[0078] Step 2.1.1: Place graphene oxide in deionized water and sonicate for 2 hours to obtain a GO dispersion solution;

[0079] Step 2.1.2: Select L-ascorbic acid as a reducing agent, add L-AA to the GO dispersion solution and stir thoroughly, filter and dry the RGO on a polytetrafluoroethylene membrane to obtain RGO on the PTFE membrane;

[0080] Step 2.2: Prepare a composite film of PAM / CITf / MWCNT / FCNT / RGO;

[0081] Step 2.2.1: Add polyacrylamide (PAM), cellulose (CITf), multi-walled carbon nanotubes (MWCNT), fluorinated carbon nanotubes (FCNT), and RGO nanoparticles prepared in step 2.1 to a chloroform solution, respectively. Control the mass percentage of PAM to 30%, the mass percentage of cellulose to 25%, and the mass percentages of RGO, MWCNT, and FCNT to 15%. Stir to ensure uniform dispersion, and then evaporate the chloroform completely after ultrasonic treatment.

[0082] Step 2.2.2: After the hydrolysis, polycondensation and aging process, a stable PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected on the polyPTFE membrane using a vacuum filtration device. The thickness of the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is controlled to be 125-135μm. The PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected by peeling it off with a polytetrafluoroethylene scraper.

[0083] Step 3: Assemble the components;

[0084] Step 3.1: Cut the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in Step 1 and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in Step 2 into 4×4cm sections. 2 ;

[0085] Step 3.2: Connect the two sides of the cut PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film and PDMS / PVDF-HFP / PAM composite film together;

[0086] Step 3.3: Copper tape is attached to the PDMS / PVDF-HFP / PAM composite film on one side as copper electrode 1, and copper tape is attached to the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film on the other side as copper electrode 1. The two sides are fixed to the mover and stator of the linear motor respectively. The position, amplitude and speed of the motor mover are controlled by adjusting the drive controller, so that the positive and negative friction layers of the device can periodically contact and separate.

[0087] Step 3.4: Connect the copper electrode 1 of the device to the test terminal of the meter with a wire to measure the output electrical performance of the device. The assembly of TENG is now complete, and the measurement can be performed next.

[0088] Example 2

[0089] Example 2 of this invention describes a method for preparing a flexible triboelectric nanogenerator based on a superhydrophobic thin film, which is implemented according to the following steps:

[0090] Step 1: Prepare PDMS / PVDF-HFP / PAM composite film, specifically by following these steps:

[0091] Step 1.1: Add polyacrylamide nanoparticles and PVDF-HFP nanoparticles to a chloroform solution, stir to disperse evenly, and obtain a chloroform mixture; control the mass percentage of PAM nanoparticles in the solution to be 10%, and control the mass percentage of PVDF-HFP nanoparticles to be 5%; stir at 45 rpm for 1.5 h.

[0092] Step 1.2: Stir the chloroform mixture obtained in Step 1.1 continuously until fully mixed, and then sonicate for 0.8 hours to evaporate the chloroform in the mixture, thereby obtaining the mixed matrix;

[0093] Step 1.3: Add the curing agent and PDMS to the mixed matrix in Step 1.2 at a weight ratio of 1:10. Sonicate the mixture of PAM, PVDF-HFP and PDMS for 15 minutes to remove air bubbles. Transfer the mixture into the cavity of a polytetrafluoroethylene membrane with a uniform cubic microstructure to obtain a composite membrane. Control the thickness of the composite membrane within the range of 135-155 μm.

[0094] Step 1.4: Place the composite film in an oven at 80°C for 2 hours to cure, and then cure at room temperature for 24 hours to obtain the PDMS / PVDF-HFP / PAM composite film.

[0095] Step 2: Prepare PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic films, specifically following these steps:

[0096] Step 2.1: Prepare RGO;

[0097] Step 2.1.1: Place graphene oxide in deionized water and sonicate for 2 hours to obtain a GO dispersion solution;

[0098] Step 2.1.2: Select L-ascorbic acid as a reducing agent, add L-AA to the GO dispersion solution and stir thoroughly, filter and dry the RGO on a polytetrafluoroethylene membrane to obtain RGO on the PTFE membrane;

[0099] Step 2.2: Prepare PAM / CITf / MWCNT / FCNT / RGO composite film;

[0100] Step 2.2.1: Add polyacrylamide (PAM), cellulose (CITf), multi-walled carbon nanotubes (MWCNT), fluorinated carbon nanotubes (FCNT), and RGO nanoparticles prepared in step 2.1 to a chloroform solution, respectively. Control the mass percentage of PAM to 30%, the mass percentage of cellulose to 25%, and the mass percentages of RGO, MWCNT, and FCNT to 15%. Stir to ensure uniform dispersion, and then evaporate the chloroform completely after ultrasonic treatment.

[0101] Step 2.2.2: After the hydrolysis, polycondensation and aging process, a stable PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected on the polyPTFE membrane using a vacuum filtration device. The thickness of the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is controlled to be 125-135μm. The PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected by peeling it off with a polytetrafluoroethylene scraper.

[0102] Step 3.1: Cut the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in Step 1 and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in Step 2 into 4×4cm sections. 2 ;

[0103] Step 3.2: Connect the two sides of the cut PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film and PDMS / PVDF-HFP / PAM composite film together;

[0104] Step 3.3: Copper tape is attached to the PDMS / PVDF-HFP / PAM composite film on one side as copper electrode 1, and copper tape is attached to the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film on the other side as copper electrode 1. The two sides are fixed to the mover and stator of the linear motor respectively. The position, amplitude and speed of the motor mover are controlled by adjusting the drive controller, so that the positive and negative friction layers of the device can periodically contact and separate.

[0105] Step 3.4: Connect the copper electrode 1 of the device to the test terminal of the meter with a wire to measure the output electrical performance of the device. The assembly of TENG is now complete, and the measurement can be performed next.

[0106] Example 3

[0107] Example 3 of this invention describes a method for preparing a flexible triboelectric nanogenerator based on a superhydrophobic thin film, which is implemented according to the following steps:

[0108] Step 1: Prepare PDMS / PVDF-HFP / PAM composite film, specifically by following these steps:

[0109] Step 1.1: Add polyacrylamide nanoparticles and PVDF-HFP nanoparticles to a chloroform solution, stir to disperse evenly, and obtain a chloroform mixture; control the mass percentage of PAM nanoparticles in the solution to be 10%, and control the mass percentage of PVDF-HFP nanoparticles to be 5%; stir at 50 rpm for 2 hours.

[0110] Step 1.2: Stir the chloroform mixture obtained in Step 1.1 continuously until fully mixed, and then sonicate for 0.8 hours to evaporate the chloroform in the mixture, thereby obtaining the mixed matrix;

[0111] Step 1.3: Add the curing agent and PDMS to the mixed matrix in Step 1.2 at a weight ratio of 1:10. Sonicate the mixture of PAM, PVDF-HFP and PDMS for 15 minutes to remove air bubbles. Transfer the mixture into the cavity of a polytetrafluoroethylene membrane with a uniform cubic microstructure to obtain a composite membrane. Control the thickness of the composite membrane within the range of 135-155 μm.

[0112] Step 1.4: Place the composite film in an oven at 80°C for 2 hours to cure, and then cure at room temperature for 24 hours to obtain the PDMS / PVDF-HFP / PAM composite film.

[0113] Step 2: Prepare PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic films, specifically following these steps:

[0114] Step 2.1: Prepare RGO;

[0115] Step 2.1.1: Place graphene oxide in deionized water and sonicate for 2 hours to obtain a GO dispersion solution;

[0116] Step 2.1.2: Select L-ascorbic acid as a reducing agent, add L-AA to the GO dispersion solution and stir thoroughly, filter and dry the RGO on a polytetrafluoroethylene membrane to obtain RGO on the PTFE membrane;

[0117] Step 2.2: Prepare PAM / CITf / MWCNT / FCNT / RGO composite film;

[0118] Step 2.2.1: Add polyacrylamide (PAM), cellulose (CITf), multi-walled carbon nanotubes (MWCNT), fluorinated carbon nanotubes (FCNT), and RGO nanoparticles prepared in step 2.1 to a chloroform solution, respectively. Control the mass percentage of PAM to 30%, the mass percentage of cellulose to 25%, and the mass percentages of RGO, MWCNT, and FCNT to 15%. Stir to ensure uniform dispersion, and then evaporate the chloroform completely after ultrasonic treatment.

[0119] Step 2.2.2: After the hydrolysis, polycondensation and aging process, a stable PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected on the polyPTFE membrane using a vacuum filtration device. The thickness of the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is controlled to be 125-135μm. The PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected by peeling it off with a polytetrafluoroethylene scraper.

[0120] Step 3: Assemble the components;

[0121] Step 3.1: Cut the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in Step 1 and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in Step 2 into 4×4cm sections. 2 ;

[0122] Step 3.2: Connect the two sides of the cut PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film and PDMS / PVDF-HFP / PAM composite film together;

[0123] Step 3.3: Copper tape is attached to the PDMS / PVDF-HFP / PAM composite film on one side as copper electrode 1, and copper tape is attached to the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film on the other side as copper electrode 1. The two sides are fixed to the mover and stator of the linear motor respectively. The position, amplitude and speed of the motor mover are controlled by adjusting the drive controller, so that the positive and negative friction layers of the device can periodically contact and separate.

[0124] Step 3.4: Connect the copper electrode 1 of the device to the test terminal of the meter with a wire to measure the output electrical performance of the device. The assembly of TENG is now complete, and the measurement can be performed next.

[0125] This invention uses a flexible thin film as the electrode base material for the positive and negative friction layers, achieving a high dielectric constant while ensuring the flexibility and stretchability of the polymer matrix. PAM is added to the positive and negative friction electrode composite material, and the flexible device made with PAM hydrogel as the base exhibits high stretchability and toughness. By introducing PAM into the positive and negative friction electrode composite material, a flexible composite film based on PAM is prepared to realize a flexible, stretchable, and highly transparent multifunctional PDMS composite material, leveraging the advantages of hydrogel, improving the conductivity of hydrogel, and enhancing the overall mechanical and biocompatibility.

[0126] Adding a curing agent to PDMS at a mass ratio of 10:1 during processing can achieve cross-linking and curing relatively quickly. PDMS composite films with uniform cubic microstructures have greater friction with positive triboelectric materials compared to ordinary PDMS composite films with flat surfaces, resulting in better electrical performance.

[0127] Compared to traditional perovskite as the positive friction material, the composite film of PDMS with a uniform cubic microstructure has a 20V higher output voltage than the ordinary PDMS composite film with a flat surface.

[0128] When preparing a PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite layer, a thicker film is not necessarily better. When the mass percentage of MWCNT / FCNT / RGO is less than 10%, there are almost no micro / nano structures on the surface, and the flexible superhydrophobic phenomenon does not appear. As the content of MWCNT / FCNT / RGO increases, the number of convex micro / nano structures increases significantly. When the mass percentage of MWCNT / FCNT / RGO is higher than 30%, a flexible superhydrophobic surface is formed due to the numerous protruding micro / nano structures. However, once the critical threshold is exceeded, with the continuous increase in the content of MWCNT / FCNT / RGO, the surface negative polarity of the tribological layer near the interface is continuously shielded, which will inhibit charge transport.

[0129] Compared to the traditional method of using perovskite as the positive friction material, doping the positive friction electrode with 15% MWCNT and 15% FCNT by mass respectively can effectively improve the output electrical performance of TENG. Adding 15% MWCNT by mass increases the output voltage by 20V; adding 15% FCNT by mass increases the output voltage by 30V.

[0130] A PAM / CITf / MWCNT / FCNT / RGO composite film is added as a flexible superhydrophobic layer. The hydrophobic cationic cellulose derivative effectively disperses MWCNTs, and the synergistic effect of the cationic cellulose derivative and MWCNTs effectively disperses RGO. Due to the adhesive effect of the cellulose derivative, the self-similar flexible superhydrophobic coating of the micro / nano structure in this invention can spontaneously form.

[0131] Adding FCNTs to flexible superhydrophobic materials results in high charge trapping capacity and high conductivity. High-conductivity charge transport paths are embedded in the dielectric layer, rapidly transporting accumulated charge deep into the material to reduce charge decay on the electrode surface. Furthermore, the highly polar fluorine groups in FCNTs enhance the inductive properties of the triboelectric layer, thereby increasing the conductivity of the positive electrode and effectively improving the output power of the TENG. This flexible superhydrophobic coating exhibits excellent waterproof properties, keeping the material dry and preventing the adhesion of various contaminants, demonstrating waterproof, antifouling, anti-adhesion, anti-icing, and anti-corrosion performance. CITf acts as a binder to effectively combine MWCNTs, FCNTs, and RGOs, resulting in a lotus leaf-like micro / nano structure.

Claims

1. A flexible triboelectric nanogenerator based on a superhydrophobic thin film, characterized in that, It includes a positive friction layer (2) and a negative friction layer (3). The positive and negative friction layers (2) are made of flexible thin film as the electrode base material. Both the positive and negative friction electrodes are based on flexible materials. There is a gap between the positive friction layer (2) and the negative friction layer (3). The edges of the two friction layers are electrically connected. The two friction layers can contact each other at the connection point to generate positive and negative static charges. Electrons flow between the two electrode layers to form alternating current. The fabrication method of the flexible triboelectric nanogenerator based on superhydrophobic thin film is carried out according to the following steps: Step 1: Prepare PDMS / PVDF-HFP / PAM composite film; Step 2: Prepare PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film; Step 3: Assemble the components; Step 1 is implemented in the following steps: Step 1.1: Add polyacrylamide nanoparticles and PVDF-HFP nanoparticles to a chloroform solution, stir and disperse evenly to obtain a chloroform mixture; The mass percentage of PAM nanoparticles in the solution was controlled at 10%, and the mass percentage of PVDF-HFP nanoparticles was controlled at 5%; the mixture was stirred at 40-50 rpm for 1-2 hours. Step 1.2: Stir the chloroform mixture obtained in Step 1.1 continuously until fully mixed, and then sonicate for 0.5-1 hour to evaporate the chloroform in the mixture to obtain the mixed matrix; Step 1.3: Add the curing agent and PDMS to the mixed matrix in Step 1.2 at a weight ratio of 1:

10. Sonicate the mixture of PAM, PVDF-HFP and PDMS for 15 minutes to remove air bubbles. Transfer the mixture into the cavity of a polytetrafluoroethylene membrane with a uniform cubic microstructure to obtain a composite membrane. Control the thickness of the composite membrane within the range of 135-155 μm. Step 1.4: Place the composite film in an oven at 80°C for 2 hours to cure, and then cure at room temperature for 24 hours to obtain the PDMS / PVDF-HFP / PAM composite film. Step 2 is implemented in the following steps: Step 2.1: Prepare RGO; Step 2.2: Prepare PAM / CITf / MWCNT / FCNT / RGO composite film; Step 2.1 is implemented in the following steps: Step 2.1.1: Place graphene oxide in deionized water and sonicate for 2 hours to obtain a dispersion of graphene oxide (GO). Step 2.1.2: Select L-ascorbic acid as a reducing agent, add L-ascorbic acid to the dispersion solution of graphene oxide (GO) and stir thoroughly. Filter and dry the RGO on a polytetrafluoroethylene (PTFE) membrane to obtain RGO on the PTFE membrane. Step 2.2 is implemented in the following steps: Step 2.2.1: Add polyacrylamide (PAM), cellulose (CITf), multi-walled carbon nanotubes (MWCNT), fluorinated carbon nanotubes (FCNT), and the RGO nanoparticles prepared in step 2.1 to the chloroform solution, stir to disperse evenly, and then evaporate the chloroform completely after ultrasonic treatment. Step 2.2.2: After the hydrolysis, polycondensation and aging process, a stable PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected on the polyPTFE membrane using a vacuum filtration device. The thickness of the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is controlled to be 125-135μm. The PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film is collected by peeling it off with a polytetrafluoroethylene scraper.

2. The flexible triboelectric nanogenerator based on a superhydrophobic thin film according to claim 1, characterized in that, The negative friction layer (3) is a PDMS / PVDF-HFP / PAM composite film with a uniform cubic microstructure. The cubic microstructure negative friction layer film is fabricated by using micro-nano cubic film tools.

3. The flexible triboelectric nanogenerator based on a superhydrophobic thin film according to claim 1, characterized in that, The positive friction layer (2) is a PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic composite film, and the positive friction electrode material is coated on the surface of PAM hydrogel; the components of the positive friction layer (2) flexible superhydrophobic composite film include a composite film formed by mixed nanoparticles of CITf, MWCNT, FCNT and RGO.

4. The flexible triboelectric nanogenerator based on a superhydrophobic thin film according to claim 1, characterized in that, Step 3 specifically involves: Step 3.1: Cut the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in Step 1 and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in Step 2 into 4×4 cm sections. 2 ; Step 3.2: Use the PDMS / PVDF-HFP / PAM composite film with uniform cubic microstructure prepared in step 1 as the negative friction layer (3), and the PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film prepared in step 2 as the positive friction layer (2). Connect the two sides of the cut PAM / CITf / MWCNT / FCNT / RGO flexible superhydrophobic film and the PDMS / PVDF-HFP / PAM composite film. Step 3.3: Copper tape is pasted on the negative friction layer (3) as copper electrode (1), and copper tape is pasted on the positive friction layer (2) as copper electrode (1). The positive friction layer (2) and the negative friction layer (3) are squeezed into a U-shape, and the two sides are fixed on the mover and stator of the linear motor respectively. The position, amplitude and speed of the motor mover are controlled by adjusting the drive controller, so that the positive and negative friction layers of the device can periodically contact and separate. Step 3.4: Connect the copper electrode (1) of the device to the test terminal of the meter with a wire to measure the output electrical performance of the device. The assembly of TENG is completed, and the measurement can be carried out next.

5. The flexible triboelectric nanogenerator based on a superhydrophobic thin film according to claim 4, characterized in that, In step 2.2.1, the mass percentage of PAM is controlled at 30%, the mass percentage of cellulose is 25%, and the mass percentages of RGO, MWCNT, and FCNT are all 15%.

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