High-stability GO / PEI flexible film, product comprising same, preparation method and application
By preparing highly stable GO/PEI flexible films, the problem of long-term stability and limited lifespan of triboelectric nanogenerators in wearable sensors was solved, achieving efficient energy harvesting and low-cost fabrication, and improving the mechanical durability and charge transfer efficiency of the sensors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-26
- Publication Date
- 2026-03-20
AI Technical Summary
Existing triboelectric nanogenerators in wearable motion sensors suffer from problems such as insufficient long-term stability, insufficient material flexibility leading to structural collapse, severe mechanical wear at the triboelectric interface, decreased charge transfer efficiency, and complex and costly fabrication processes.
Highly stable GO/PEI flexible films were prepared using graphene oxide (GO) and polyethyleneimine (PEI). Through a vacuum filtration-assisted self-assembly method, films with high flexibility and mechanical strength were prepared and applied to triboelectric nanogenerators.
This improved the mechanical durability and charge transfer efficiency of triboelectric nanogenerators, reduced material preparation costs, and enabled long-term stable operation and efficient energy harvesting of wearable sensors.
Smart Images
Figure CN121699203A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of flexible sensor technology, and particularly relates to a highly stable GO / PEI flexible film, products containing the same, preparation methods, and applications. Background Technology
[0002] With the increasing aging of the global population and the growing demand for personalized healthcare, wearable devices for real-time, non-invasive monitoring of physiological and motor signals have become a research focus. Motion sensors are key components of these systems, capable of capturing a wide range of movements, from subtle gestures to whole-body motions such as finger flexion and extension, joint rotation, and gait dynamics, providing valuable data for activity assessment and rehabilitation guidance. However, the widespread application of wearable motion sensors is constrained by a long-standing bottleneck: their reliance on conventional batteries. Limited battery life, the need for frequent replacements, and negative environmental impacts severely affect the practicality and sustainability of such devices. To address this challenge, integrated energy harvesting and sensing strategies have attracted widespread attention. Among these, piezoelectric nanogenerators (PENGs), while extensively studied, typically require high mechanical stress and have limited efficiency at low frequencies, making them unsuitable for biomechanical sensing. In contrast, triboelectric nanogenerators (TENGs) have garnered significant attention due to their ability to efficiently harvest low-frequency mechanical energy (approximately 1-5 Hz) from human activity, as well as their advantages of lightweight, flexible structure, and diverse materials.
[0003] Although the output performance and environmental adaptability of triboelectric nanogenerators have improved significantly in recent years, demonstrating excellent application potential in wearable motion sensors, existing technologies still suffer from several key drawbacks that restrict practical applications. For example, in terms of long-term stability, insufficient material flexibility can easily lead to structural collapse during operation, and severe mechanical wear at the triboelectric interface results in decreased charge transfer efficiency and limited device lifespan after long-term operation. Regarding material preparation, the complex fabrication process and high cost of large-scale production, coupled with the difficulty in precisely arranging the material's microstructure, lead to poor performance repeatability, further hindering the technology's transition from the laboratory to industrial application. Summary of the Invention
[0004] To address the technical problem of poor charge transfer efficiency (i.e., poor cycle life) of triboelectric nanogenerators in wearable motion sensors after long-term operation, this invention proposes a highly stable GO / PEI flexible film, products containing the film, preparation methods, and applications.
[0005] To achieve the above objectives, the present invention provides the following technical solution:
[0006] A method for preparing a highly stable GO / PEI flexible film includes the following steps:
[0007] Aqueous dispersions of graphene oxide (GO) and polyethyleneimine (PEI) were mixed, centrifuged, and washed with pH-adjusting solution. The resulting product was then redispersed and deposited onto a polyethersulfone microporous membrane by vacuum filtration. After drying, the membrane was peeled off to obtain a highly stable GO / PEI flexible film.
[0008] Beneficial Effects: This invention utilizes graphene oxide (GO) and polyethyleneimine (PEI) to prepare highly stable GO / PEI flexible films. GO possesses a high specific surface area, mechanical flexibility, and abundant oxygen-containing functional groups, which promote efficient triboelectric charge generation. PEI is a water-soluble polycation that can generate strong electrostatic interactions with GO, enhancing interfacial adhesion and structural stability. The combined properties of these two materials endow the GO / PEI composite film with excellent flexibility and mechanical strength (see details). Figure 7 The redshift of the C=O and NH peaks in the infrared spectrum of Example 1 compared to Comparative Example 1 indicates that there is an electrostatic interaction between PEI and GO. Figure 10 The Young's modulus of Example 1 is higher than that of Comparative Example 1, indicating that GO / PEI has better mechanical properties than GO; that is... Figure 7 , 10 Together, they demonstrate a synergistic effect between GO and PEI to enhance mechanical properties. Furthermore, the GO / PEI membrane disclosed in this invention is prepared using a simple and environmentally friendly vacuum filtration-assisted self-assembly method, enabling large-scale production and conformal integration into wearable sensors.
[0009] Optionally, the weight-average molecular weight of polyethyleneimine in the polyethyleneimine aqueous dispersion is 2000 Da (linear PEI), 25000 Da (branched PEI), or 750000 Da (linear PEI).
[0010] Optionally, the mass ratio of graphene oxide in the graphene oxide aqueous dispersion to polyethyleneimine in the polyethyleneimine aqueous dispersion is 1:10.
[0011] Furthermore, the concentration of the graphene oxide aqueous dispersion is 0.5 mg / mL. -1 ;
[0012] The concentration of the polyethyleneimine aqueous dispersion is 2 mg / mL. -1 .
[0013] Furthermore, the pH of the polyethyleneimine aqueous dispersion is 2-12.
[0014] Furthermore, when the pH of the polyethyleneimine aqueous dispersion is ≤6, the pH adjusting solution is dilute hydrochloric acid at the corresponding pH.
[0015] When the pH of the polyethyleneimine aqueous dispersion is greater than 6, the pH adjusting solution is deionized water.
[0016] Optionally, the centrifugation conditions are: a rotation speed of 3200 rpm and a centrifugation time of 45 min.
[0017] Optionally, the vacuum filtration time is 6-12 hours; and / or,
[0018] The drying time is 6-12 hours.
[0019] A highly stable GO / PEI flexible film was prepared by the above-described preparation method.
[0020] The application of the aforementioned highly stable GO / PEI flexible film in the fabrication of triboelectric nanogenerators.
[0021] A triboelectric nanogenerator, the raw material of which includes the highly stable GO / PEI flexible film.
[0022] The triboelectric nanogenerator comprises, from bottom to top:
[0023] Indium tin oxide / polyethylene terephthalate (ITO / PET) film underlayer;
[0024] Kapton PI thin film layer;
[0025] High-stability GO / PEI flexible thin film layer;
[0026] Kapton PI thin film layer;
[0027] Aluminum foil top layer.
[0028] Compared with the prior art, the present invention has the following advantages and technical effects:
[0029] The high-stability GO / PEI flexible film disclosed in this invention has two advantages. First, the preparation process is simple, requiring only vacuum filtration to obtain a uniform film, which can effectively reduce the cost of large-scale material production. Second, the strong electrostatic interaction between the flexible skeleton of GO and the flexible molecular chains of PEI enhances the stability of the molecular interface, endowing the film with excellent flexibility and mechanical strength, greatly improving the mechanical durability of the film, and effectively solving the problem of limited lifespan of wearable motion sensors based on triboelectric nanogenerators. Attached Figure Description
[0030] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:
[0031] Figure 1This is a schematic diagram of the triboelectric nanogenerator structure prepared using the highly stable GO / PEI flexible thin film obtained in the embodiments of the present invention;
[0032] Figure 2 Scanning electron microscope image (40 μm) of the surface of the highly stable GO / PEI flexible film 1 prepared in Example 1.
[0033] Figure 3 Scanning electron microscope image (5 μm) of a cross section of the highly stable GO / PEI flexible thin film 1 prepared in Example 1.
[0034] Figure 4 The elemental surface distribution of the highly stable GO / PEI flexible film 1 prepared in Example 1 is shown in the diagram.
[0035] Figure 5 A scanning electron microscope image of the surface of the pure GO film prepared in Comparative Example 1;
[0036] Figure 6 A scanning electron microscope image of the cross-section of the pure GO thin film prepared in Comparative Example 1;
[0037] Figure 7 Infrared spectra of the highly stable GO / PEI flexible film 1 prepared in Example 1, the pure GO film prepared in Comparative Example 1, and the PEI raw material;
[0038] Figure 8 X-ray diffraction patterns of the highly stable GO / PEI flexible films 1-2 prepared in Examples 1-2 and the pure GO film prepared in Comparative Example 1;
[0039] Figure 9 The graph shows a comparison of the output voltages of the triboelectric nanogenerators fabricated from the thin films of Examples 1-4 and Comparative Examples 1-2.
[0040] Figure 10 This is a comparison chart of the Young's modulus of the thin films in Examples 1-4 and Comparative Examples 1-2;
[0041] Figure 11 Comparison of the cyclic performance of the triboelectric nanogenerators prepared in Examples 1-4 and Comparative Examples 1-2 at a force frequency of 1 Hz;
[0042] Figure 12 The voltage signal response diagram of the triboelectric nanogenerator 1 based on the highly stable GO / PEI flexible thin film 1 obtained in Example 1 for detecting various human motion signals is shown. Detailed Implementation
[0043] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.
[0044] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.
[0045] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.
[0046] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.
[0047] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.
[0048] The first aspect of the present invention provides a highly stable GO / PEI flexible film, wherein the electrostatic interaction between the flexible skeleton of GO and the flexible molecular chains of PEI endows the GO / PEI flexible film with excellent flexibility and mechanical strength, thereby possessing excellent mechanical durability.
[0049] A second aspect of the present invention provides a method for preparing the highly stable GO / PEI flexible film described in the first aspect, comprising the following steps:
[0050] The original graphene oxide aqueous dispersion (concentration 5 mg / mL) -1 (40 mL) Dilute 10 times to obtain the GO aqueous dispersion to be used;
[0051] Dissolve 800 mg of polyethyleneimine (PEI) in 400 mL of NaCl solution (concentration 0.1 mol / L). -1 ), to obtain the PEI aqueous dispersion to be used (concentration 2 mg / mL) -1 );
[0052] The pH of the PEI aqueous dispersion was adjusted to different values using hydrochloric acid or sodium hydroxide solution.
[0053] Take six 50 mL centrifuge tubes and add 8 mL of graphene oxide dispersion (0.5 mg / mL) to each tube. -1 ) and 20 mL of polyethyleneimine dispersion (2 mg / mL) -1 Mix thoroughly. Centrifuge the mixture, remove the supernatant, and then wash it with the corresponding pH adjustment solution. The purpose of washing with the corresponding pH adjustment solution is to ensure the pH environment of the mixture so as to ensure that the molecular structure of the film prepared later is not affected. After centrifugation, remove the supernatant and collect all the precipitate into a centrifuge tube and add sufficient pH adjustment solution to disperse it evenly, so as to obtain the mixture to be filtered and formed into a film.
[0054] The mixture to be filtered and film-forming obtained above is vacuum filtered through a polyethersulfone (PES) microporous filter membrane. After filtration, a GO / PEI membrane with a polyethersulfone filter membrane is obtained. After drying in a drying cabinet, the GO / PEI membrane is peeled off from the polyethersulfone filter membrane to obtain a high-stability GO / PEI flexible membrane.
[0055] In some optional embodiments, the weight-average molecular weights of the PEIs used in the PEI aqueous dispersions are 2000 Da, 25000 Da, and 750000 Da, respectively, wherein the PEI with a weight-average molecular weight of 25000 Da is a branched PEI, and the other two are linear PEIs.
[0056] And / or, the pH range of the PEI aqueous dispersion is adjusted to 2–12, the hydrochloric acid used is 37% by mass, and the concentration of the sodium hydroxide solution is 1 mol / mL. -1 ;
[0057] And / or, the mass ratio of GO to PEI in the mixture is 1:10.
[0058] In some alternative embodiments, the centrifugation speed is 3200 rpm and the time is 45 min;
[0059] And / or, the pH adjusting solution is dilute hydrochloric acid with different pH values, wherein when pH>6, the pH adjusting solution used is deionized water;
[0060] And / or, the pH adjustment liquid volume used to disperse the GO / PEI precipitate is 25~35 mL;
[0061] And / or, the vacuum filtration time is 6~12 h;
[0062] And / or, the drying time is 6~12 h.
[0063] A third aspect of the present invention provides the application of the above-described highly stable GO / PEI flexible film to a triboelectric nanogenerator.
[0064] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.
[0065] All raw materials used in this invention were purchased from the market.
[0066] The technical solution of the present invention will be further illustrated by the following embodiments.
[0067] Example 1
[0068] This embodiment 1 provides a method for preparing a highly stable GO / PEI flexible thin film 1 and a triboelectric nanogenerator 1, the specific steps of which are as follows:
[0069] (1) Preparation of highly stable GO / PEI flexible film 1:
[0070] The original graphene oxide (GO) dispersion (concentration 5 mg / mL) -1 (40 mL) Diluted 10 times to obtain a concentration of 0.5 mg / mL -1 GO aqueous dispersion to be used;
[0071] 800 mg of branched polyethyleneimine (PEI, weight average molecular weight 25000 Da) was dissolved in 400 mL of 0.1 mol / L solution. -1 In NaCl solution, a PEI aqueous dispersion (PEI concentration of 2 mg / mL) was obtained for use. -1 Adjust the pH of the PEI aqueous dispersion to 10 using hydrochloric acid or sodium hydroxide solution.
[0072] Take six 50 mL centrifuge tubes and add 8 mL of the prepared GO aqueous dispersion (0.5 mg / mL) to each tube. -1 ) and 20 mL of polyethyleneimine dispersion (2 mg / mL) -1The mixture was then thoroughly mixed to obtain a homogeneous solution. The solution was centrifuged at 3200 rpm for 45 min. After removing the supernatant, the mixture was washed with deionized water at the same speed for 45 min. After centrifugation, the supernatant was removed, and all the precipitates were collected in a centrifuge tube and 30 mL of deionized water was added to disperse them evenly, thus obtaining the solution to be filtered and formed into a film.
[0073] The mixture to be filtered and film-forming obtained above was vacuum filtered through a polyethersulfone (PES) microporous filter membrane for 8 h. After filtration, a GO / PEI membrane with a polyethersulfone filter membrane was obtained. After drying in a drying cabinet for 8 h, the GO / PEI membrane was peeled off from the polyethersulfone filter membrane to obtain a high-stability GO / PEI flexible membrane 1.
[0074] (2) Preparation of triboelectric nanogenerator 1:
[0075] A 4.5 cm × 4.5 cm indium tin oxide / polyethylene terephthalate (ITO / PET) film was cut as the encapsulation substrate for the triboelectric nanogenerator. To detect the output voltage signal of the triboelectric nanogenerator, a high-purity copper wire was connected to the ITO layer of the substrate with silver paste and fixed with copper foil. Then, a Kapton PI film was deposited on the ITO layer. Next, the high-stability GO / PEI flexible film 1 obtained in step (1) was stacked on the Kapton PI film, and another Kapton PI film was deposited on the GO / PEI flexible film. In order to form an air gap between the film and the Kapton PI film above it to ensure the normal operation of the triboelectric nanogenerator, a 5 × 5 hole array was pierced in the Kapton PI film with a needle before the second Kapton PI film was deposited. Finally, an aluminum foil was placed on top, and the high-purity copper wire was connected to the top layer of the aluminum foil with silver paste to obtain the triboelectric nanogenerator 1. The open-circuit voltage can be tested by connecting the two high-purity copper wires of the triboelectric nanogenerator 1 to an electrochemical workstation.
[0076] Example 2
[0077] This embodiment 2 provides a method for preparing a highly stable GO / PEI flexible thin film 2 and a triboelectric nanogenerator 2, the specific steps of which are as follows:
[0078] (1) Preparation of highly stable GO / PEI flexible film 2:
[0079] The original graphene oxide (GO) dispersion (concentration 5 mg / mL) -1 (40 mL) Diluted 10 times to obtain a concentration of 0.5 mg / mL -1 GO aqueous dispersion to be used;
[0080] 800 mg of branched polyethyleneimine (PEI, weight average molecular weight 25000 Da) was dissolved in 400 mL of 0.1 mol / L solution. -1 NaCl solution was used to obtain a PEI aqueous dispersion (PEI concentration was 2 mg / mL). -1 ); Adjust the pH of the PEI aqueous dispersion to 2 using hydrochloric acid solution.
[0081] Take six 50 mL centrifuge tubes and add 8 mL of the prepared GO aqueous dispersion (0.5 mg / mL) to each tube. -1 ) and 20 mL of polyethyleneimine dispersion (2 mg / mL) -1 The mixture was then thoroughly mixed to obtain a homogeneous solution. The solution was centrifuged at 3200 rpm for 45 min. After removing the supernatant, the mixture was washed with a dilute hydrochloric acid solution at pH 2 at the same speed for 45 min. After centrifugation, the supernatant was removed, and all precipitates were collected in a centrifuge tube and 30 mL of a dilute hydrochloric acid solution at pH 2 was added to disperse the precipitate evenly, resulting in the solution to be filtered and used for film formation.
[0082] The mixture to be filtered and film-forming obtained above was vacuum filtered through a polyethersulfone (PES) microporous filter membrane for 8 h. After filtration, a GO / PEI membrane with a polyethersulfone filter membrane was obtained. After drying in a drying cabinet for 8 h, the GO / PEI membrane was peeled off from the polyethersulfone filter membrane to obtain a high-stability GO / PEI flexible membrane 2.
[0083] (2) Preparation of triboelectric nanogenerator 2:
[0084] A 4.5 cm × 4.5 cm indium tin oxide / polyethylene terephthalate (ITO / PET) film was cut as the encapsulation substrate for the triboelectric nanogenerator. To detect the output voltage signal of the triboelectric nanogenerator, a high-purity copper wire was connected to the ITO layer of the substrate with silver paste and fixed with copper foil. Then, a Kapton PI film was deposited on the ITO layer. Next, the high-stability GO / PEI flexible film 2 obtained in Example 2 was stacked on the Kapton PI film, and another Kapton PI film was deposited on top of the GO / PEI flexible film. To form an air gap between the film and the Kapton PI film above it to ensure the normal operation of the triboelectric nanogenerator, a 5 × 5 hole array was pierced in the Kapton PI film with a needle before depositing the second Kapton PI film. Finally, an aluminum foil was placed on top, and a high-purity copper wire was connected to the top layer of the aluminum foil with silver paste, thus obtaining the triboelectric nanogenerator 2. The open-circuit voltage can be tested by connecting the two high-purity copper wires of the triboelectric nanogenerator 2 to an electrochemical workstation.
[0085] Example 3
[0086] This embodiment 3 provides a method for preparing a highly stable GO / PEI flexible thin film 3 and a triboelectric nanogenerator 3, the specific steps of which are as follows:
[0087] (1) Preparation of highly stable GO / PEI flexible film 3:
[0088] The original graphene oxide (GO) dispersion (concentration 5 mg / mL) -1 (40 mL) Diluted 10 times to obtain a concentration of 0.5 mg / mL -1 GO aqueous dispersion to be used;
[0089] 800 mg of linear polyethyleneimine (PEI, weight-average molecular weight 2000 Da) was dissolved in 400 mL of 0.1 mol / L solution. -1 NaCl solution was used to obtain a PEI aqueous dispersion (PEI concentration was 2 mg / mL). -1 Adjust the pH of the PEI aqueous dispersion to 10 using hydrochloric acid or sodium hydroxide solution.
[0090] Take six 50 mL centrifuge tubes and add 8 mL of the prepared GO aqueous dispersion (0.5 mg / mL) to each tube. -1 ) and 20 mL of polyethyleneimine dispersion (2 mg / mL) -1 The mixture was then thoroughly mixed to obtain a homogeneous solution. The solution was centrifuged at 3200 rpm for 45 min. After removing the supernatant, the mixture was washed with deionized water at the same speed for 45 min. After centrifugation, the supernatant was removed, and all the precipitates were collected in a centrifuge tube and 30 mL of deionized water was added to disperse them evenly, thus obtaining the solution to be filtered and formed into a film.
[0091] The mixture to be filtered and film-forming obtained above was vacuum filtered through a polyethersulfone (PES) microporous filter membrane for 8 h. After filtration, a GO / PEI membrane with a polyethersulfone filter membrane was obtained. After drying in a drying cabinet for 8 h, the GO / PEI membrane was peeled off from the polyethersulfone filter membrane to obtain a high-stability GO / PEI flexible membrane 3.
[0092] (2) Preparation of triboelectric nanogenerator 3:
[0093] A 4.5 cm × 4.5 cm indium tin oxide / polyethylene terephthalate (ITO / PET) film was cut as the encapsulation substrate for the triboelectric nanogenerator. To detect the output voltage signal of the triboelectric nanogenerator, a high-purity copper wire was connected to the ITO layer of the substrate with silver paste and fixed with copper foil. Then, a Kapton PI film was deposited on the ITO layer. Next, the high-stability GO / PEI flexible film 3 obtained in Example 3 was stacked on the Kapton PI film, and another Kapton PI film was deposited on top of the GO / PEI flexible film. To form an air gap between the film and the Kapton PI film above it to ensure the normal operation of the triboelectric nanogenerator, a 5 × 5 hole array was pierced in the Kapton PI film with a needle before depositing the second Kapton PI film. Finally, an aluminum foil was placed on top, and a high-purity copper wire was connected to the top layer of the aluminum foil with silver paste, thus obtaining the triboelectric nanogenerator 3. The open-circuit voltage can be tested by connecting the two high-purity copper wires of the triboelectric nanogenerator 3 to an electrochemical workstation.
[0094] Example 4
[0095] This embodiment 4 provides a method for preparing a highly stable GO / PEI flexible thin film 4 and a triboelectric nanogenerator 4, the specific steps of which are as follows:
[0096] (1) Preparation of highly stable GO / PEI flexible film 4:
[0097] The original graphene oxide (GO) dispersion (concentration 5 mg / mL) -1 (40 mL) Diluted 10 times to obtain a concentration of 0.5 mg / mL -1 GO aqueous dispersion to be used;
[0098] 800 mg of linear polyethyleneimine (PEI, weight-average molecular weight 750,000 Da) was dissolved in 400 mL of 0.1 mol / L solution. -1 NaCl solution was used to obtain a PEI aqueous dispersion (PEI concentration was 2 mg / mL). -1 Adjust the pH of the PEI aqueous dispersion to 10 using hydrochloric acid or sodium hydroxide solution.
[0099] Take six 50 mL centrifuge tubes and add 8 mL of the prepared GO aqueous dispersion (0.5 mg / mL) to each tube. -1 ) and 20 mL of polyethyleneimine dispersion (2 mg / mL) -1The mixture was then thoroughly mixed to obtain a homogeneous solution. The solution was centrifuged at 3200 rpm for 45 min. After removing the supernatant, the mixture was washed with deionized water at the same speed for 45 min. After centrifugation, the supernatant was removed, and all the precipitates were collected in a centrifuge tube and 30 mL of deionized water was added to disperse them evenly, thus obtaining the solution to be filtered and formed into a film.
[0100] The mixture to be filtered and film-forming obtained above was vacuum filtered through a polyethersulfone (PES) microporous filter membrane for 8 hours. After filtration, a GO / PEI membrane with a polyethersulfone filter membrane was obtained. After drying in a drying cabinet for 8 hours, the GO / PEI membrane was peeled off from the polyethersulfone filter membrane to obtain a high-stability GO / PEI flexible membrane 4.
[0101] (2) Preparation of triboelectric nanogenerator 4:
[0102] A 4.5 cm × 4.5 cm indium tin oxide / polyethylene terephthalate (ITO / PET) film was cut as the encapsulation substrate for the triboelectric nanogenerator. To detect the output voltage signal of the triboelectric nanogenerator, a high-purity copper wire was connected to the ITO layer of the substrate with silver paste and fixed with copper foil. Then, a Kapton PI film was coated on the ITO layer. Next, the high-stability GO / PEI flexible film 4 obtained in step (1) was stacked on the Kapton PI film, and another Kapton PI film was coated on the GO / PEI flexible film. In order to form an air gap between the film and the Kapton PI film above it to ensure the normal operation of the triboelectric nanogenerator, a 5 × 5 hole array was pierced in the Kapton PI film with a needle before coating the second Kapton PI film. Finally, an aluminum foil was coated on the top layer, and the high-purity copper wire was connected to the top layer of the aluminum foil with silver paste to obtain the triboelectric nanogenerator 4. The open circuit voltage can be tested by connecting the two high-purity copper wires of the triboelectric nanogenerator 4 to an electrochemical workstation.
[0103] Comparative Example 1
[0104] In Comparative Example 1, 48 mL of the prepared GO aqueous dispersion (0.5 mg / mL) was directly added. -1 After vacuum filtration through a polyethersulfone (PES) microporous filter membrane and peeling to obtain a pure GO film, a triboelectric nanogenerator was prepared according to the methods described in Examples 1-4 above, and the open-circuit voltage was tested.
[0105] Comparative Example 2
[0106] Comparative Example 2 provides a method for preparing a GO / PEI flexible thin film and a triboelectric nanogenerator. The only difference from Example 1 is that the weight-average molecular weight of branched polyethyleneimine (PEI, with a weight-average molecular weight of 25,000 Da) is replaced with 800 Da. The other preparation process and conditions are the same as in Example 1.
[0107] Effect verification
[0108] To verify the relevant properties of the high-stability GO / PEI flexible films 1-4 prepared in Examples 1-4 and the films prepared in Comparative Examples 1-2, performance tests were conducted on the high-stability GO / PEI flexible films 1-4 prepared in Examples 1-4 and the films prepared in Comparative Examples 1-2. The test results are shown in Table 1 and Table 2. Figures 2-12 As shown.
[0109] Figure 1 This is a schematic diagram of the triboelectric nanogenerator structure fabricated using the highly stable GO / PEI flexible thin film obtained in this embodiment of the invention. It shows the subdivided structure of the triboelectric nanogenerator fabricated from the highly stable GO / PEI flexible thin film. The highly stable GO / PEI flexible thin film and the underlying Kapton PI thin film form a triboelectric couple, which outputs AC voltage through a continuous contact-separation cycle mechanism.
[0110] Figure 2 Scanning electron microscope image (40 μm) of the surface of the highly stable GO / PEI flexible film 1 prepared in Example 1. According to... Figure 2 It can be seen that the high-stability GO / PEI flexible film 1 prepared in Example 1 has a wrinkled structure on its surface, which creates an uneven surface, increases the surface roughness of the film, and is beneficial to triboelectric output.
[0111] Figure 3 Scanning electron microscope image (5 μm) of a cross-section of the highly stable GO / PEI flexible thin film 1 prepared in Example 1. According to... Figure 3 It can be seen that the highly stable GO / PEI flexible film 1 prepared in Example 1 has an obvious layered stacked structure and the thickness of the film is about 12 μm.
[0112] Figure 4 The elemental distribution of the highly stable GO / PEI flexible film 1 prepared in Example 1 is shown in the figure. Figure 4 It can be seen that the N element on the surface of the highly stable GO / PEI flexible film 1 prepared in Example 1 is uniformly distributed, indicating that PEI is uniformly intercalated between the GO layers.
[0113] Figure 5 Scanning electron microscope image of the surface of the pure GO film prepared for Comparative Example 1. According to... Figure 5It can be seen that the pure GO film prepared in Comparative Example 1 has a smooth and flat surface with few wrinkles.
[0114] Figure 6 Scanning electron microscope image of a cross-section of the pure GO thin film prepared for Comparative Example 1. According to... Figure 6 It can be seen that the pure GO film prepared in Comparative Example 1 has a distinct layered stacked structure and a film thickness of about 5 μm.
[0115] Figure 7 Infrared spectra of the highly stable GO / PEI flexible film 1 prepared in Example 1, the pure GO film prepared in Comparative Example 1, and the PEI raw material. Figure 7 It can be seen that the infrared spectrum of the highly stable GO / PEI flexible film 1 prepared in Example 1 simultaneously exhibits the characteristic peaks of both the pure GO film prepared in Comparative Example 1 and the PEI raw material, further demonstrating that GO and PEI were successfully composited, and the highly stable GO / PEI flexible film 1 was successfully prepared. Furthermore, the C=O and NH characteristic peaks of the highly stable GO / PEI flexible film 1 prepared in Example 1 show a redshift compared to the C=O characteristic peak of the pure GO film prepared in Comparative Example 1 and the NH characteristic peak of the raw material PEI, indicating that there is an electrostatic interaction between GO and PEI, which improves the mechanical properties of the film.
[0116] Figure 8 X-ray diffraction patterns of the highly stable GO / PEI flexible films 1-2 prepared in Examples 1-2 and the pure GO film prepared in Comparative Example 1. Figure 8 It can be seen that the X-ray diffraction pattern of the pure GO film prepared in Comparative Example 1 shows a single peak, with the peak position corresponding to an interlayer spacing of 7.1 Å for the pure GO film. The diffraction peaks of the high-stability GO / PEI flexible films 1-2 prepared in Examples 1-2 all appear at positions with smaller diffraction angles θ, indicating larger interlayer spacing, further illustrating that the structure of GO / PEI is a layered stacked structure with PEI intercalated between GO layers. Among them, the X-ray diffraction pattern of the high-stability GO / PEI flexible film 2 prepared in Example 2 shows a single peak, with a corresponding interlayer spacing of 11.4 Å. This is because the low pH environment causes PEI molecular chains to intercalate in an extended state between GO layers and enhances the protonation degree of PEI, weakening the triboelectric output. The X-ray diffraction pattern of the high-stability GO / PEI flexible film 1 prepared in Example 1 shows a double peak, corresponding to interlayer spacings of 21.6 Å and 10.9 Å, respectively. This is because the high pH environment reduces the protonation degree of PEI, and PEI molecular chains intercalate in a randomized state between GO layers, not only constructing an uneven surface (see Figure 2 Furthermore, the weakening effect of PEI on triboelectric output is greatly reduced due to protonation, thereby promoting triboelectric output.
[0117] Table 1 summarizes and displays data on various effects, such as Young's modulus, output voltage, and cycle performance of the thin films prepared in Examples 1-4 and Comparative Examples 1-2.
[0118] Table 1
[0119] Output voltage (V) Young's modulus (GPa) Cyclic performance (cycles) Example 1 15.16 2.43 38000 Example 2 13.01 1.91 15000 Example 3 12.98 1.93 15000 Example 4 11.39 2.21 20000 Comparative Example 1 10.46 1.78 9000 Comparative Example 2 10.82 1.85 10000
[0120] Figure 9 This is a comparison of the output voltages of triboelectric nanogenerators fabricated from the thin films of Examples 1-4 and Comparative Examples 1-2. According to... Figure 9 It can be seen that the output voltages of Examples 1-4 and Comparative Example 2 are all higher than that of Comparative Example 1, indicating that PEI intercalation into GO generally benefits the output of triboelectricity, but the increase in output voltage in Comparative Example 2 is not significant. It is worth noting that the output voltage of Example 1 is significantly higher than that of the other examples. This is because the high-stability GO / PEI flexible film 1 prepared in Example 1 experiences the least weakening effect of protonated PEI and has a uniformly distributed and sufficient wrinkled surface, which maximizes the triboelectric output.
[0121] Figure 10 This is a comparison chart of the Young's modulus of the films in Examples 1-4 and Comparative Examples 1-2. The Young's modulus was calculated through tensile testing. Figure 10 It can be seen that the Young's modulus of Examples 1-4 and Comparative Example 2 is higher than that of Comparative Example 1, indicating that the electrostatic interaction between PEI and GO enhances the mechanical properties of the film, which is beneficial for constructing a highly stable triboelectric nanogenerator and improving cycle life.
[0122] Figure 11 The graph shows a comparison of the cyclic performance of the triboelectric nanogenerators prepared in Examples 1-4 and Comparative Examples 1-2 at a force frequency of 1 Hz. According to... Figure 11 It can be seen that Examples 1-4 and Comparative Example 2 all exhibit better cycling performance than Comparative Example 1. Although Comparative Example 2 also shows improved cycling performance compared to Comparative Example 1, the improvement is not significant; while the cycling performance of Examples 1-4 is significantly improved compared to Comparative Examples 1 and 2. It is worth noting that the improvement in cycling performance of Example 1 is the most significant, successfully constructing a highly stable triboelectric nanogenerator, which can effectively solve the problem of limited cycle life of wearable motion monitoring sensors based on triboelectric nanogenerators.
[0123] Figure 12 This is a voltage signal response diagram for the triboelectric nanogenerator 1 based on the highly stable GO / PEI flexible thin film 1 obtained in Example 1, used to detect various human motion signals. Figure 12 It can be seen that the triboelectric nanogenerator 1 prepared in Example 1 can effectively detect various motion signals of the human body and is expected to be widely used in the field of wearable motion monitoring sensors.
[0124] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a highly stable GO / PEI flexible thin film, characterized in that, Includes the following steps: The graphene oxide aqueous dispersion and the polyethyleneimine aqueous dispersion were mixed, centrifuged, washed with pH-adjusting solution, and the resulting product was redispersed. The product was then vacuum filtered onto a polyethersulfone microporous membrane to form a film. After drying, the film was peeled off to obtain the highly stable GO / PEI flexible film.
2. The method for preparing a highly stable GO / PEI flexible film according to claim 1, characterized in that, The weight-average molecular weight of polyethyleneimine in the polyethyleneimine aqueous dispersion is 2000 Da, 25000 Da, or 750000 Da.
3. The method for preparing a highly stable GO / PEI flexible thin film according to claim 1, characterized in that, The mass ratio of graphene oxide in the aqueous dispersion to polyethyleneimine in the aqueous dispersion is 1:
10.
4. The method for preparing a highly stable GO / PEI flexible film according to claim 3, characterized in that, The concentration of the graphene oxide aqueous dispersion is 0.5 mg / mL. -1 ; and / or, The concentration of the polyethyleneimine aqueous dispersion is 2 mg / mL. -1 .
5. The method for preparing a highly stable GO / PEI flexible film according to claim 1, characterized in that, The pH of the polyethyleneimine aqueous dispersion is 2-12.
6. The method for preparing a highly stable GO / PEI flexible film according to claim 1, characterized in that, The centrifugation conditions are: centrifugation at 3200 rpm for 45 min; and / or, The vacuum filtration time is 6-12 hours; and / or, The drying time is 6-12 hours.
7. A highly stable GO / PEI flexible film, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.
8. The application of a highly stable GO / PEI flexible thin film as described in claim 7 in the fabrication of a triboelectric nanogenerator.
9. A triboelectric nanogenerator, characterized in that, The raw materials include the high-stability GO / PEI flexible film as described in claim 7.
10. A triboelectric nanogenerator according to claim 9, characterized in that, From bottom to top, they include: Indium tin oxide / polyethylene terephthalate film underlayer; Kapton PI thin film layer; The highly stable GO / PEI flexible thin film layer; Kapton PI thin film layer; Aluminum foil top layer.