A triboelectric nanogenerator and its preparation method

Abstract

This invention provides a triboelectric nanogenerator and its fabrication method. The generator operates in a vertical contact-separation mode, with a positive friction layer of PET film and a negative friction layer of PDMS composite film with a single layer of dense SiO₂ microspheres inserted on its surface. The fabrication process employs a two-step spin-coating method: first, a PDMS solution is spin-coated onto a substrate; then, a suspension of SiO₂ microspheres is spin-coated onto the uncured surface. After heating and curing, a composite negative friction layer is formed, which is then assembled with electrodes and a support structure. This invention significantly increases the triboelectric contact area and enhances charge trapping capability by constructing the SiO₂ microsphere insertion layer, thereby greatly improving output performance. Furthermore, the fabrication process is simple and low-cost, making it suitable for powering microelectronic devices and self-powered sensing applications.

Description

Technical Field

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

[0002] Triboelectric nanogenerators (TENGs) are a novel energy harvesting technology that converts environmental mechanical energy into electrical energy based on contact electrification and electrostatic induction coupling effects. Since their initial report in 2012, TENGs have attracted widespread attention from academia and industry due to their advantages such as a wide range of material choices, flexible structural design, low cost, and high energy conversion efficiency under low-frequency vibration environments. Currently, TENGs have been explored for applications in several cutting-edge fields, including self-powered microelectronic devices, wearable electronic devices, environmental monitoring sensor networks, and ocean wave energy harvesting.

[0003] Depending on their operating modes, TENGs are mainly classified into four basic types: vertical contact-separation mode, horizontal sliding mode, single-electrode mode, and independent-layer mode. Among them, the vertical contact-separation mode has become one of the most commonly used and most popular operating modes due to its advantages such as simple structure, high instantaneous power density, and ease of integration and packaging. A typical vertical contact-separation mode TENG usually includes two electrodes, two friction layers with opposite triboelectric polarities, and a support structure for deformation recovery. When an external force causes the two friction layers to come into contact, equal amounts of opposite charges are generated on the surface due to the difference in triboelectric sequence. When the external force is released and the two friction layers separate, a potential difference is formed between the electrodes, driving electrons to flow in the external circuit, thereby outputting electrical energy.

[0004] Despite its numerous advantages, the triboelectric effect (TENG) still faces a key bottleneck in practical applications: its output current is typically low, limiting its overall output power density and making it difficult to meet the power demands of some high-power microelectronic devices. Research indicates that the output performance of the TENG is closely related to the charge density on the surface of the triboelectric layer, which in turn largely depends on the effective contact area between the two triboelectric layers. Therefore, maximizing the contact area of ​​the triboelectric interface within a limited device volume has become one of the core scientific challenges in improving the output performance of the TENG.

[0005] To address this issue, research teams both domestically and internationally have conducted extensive work. Common techniques include: constructing periodic microstructures, such as pyramid arrays, cubic arrays, or nanowire arrays, on the surface of the friction layer using micro / nano fabrication techniques such as photolithography, plasma etching, and chemical etching; or preparing friction layers with porous or fibrous structures through electrospinning, template methods, and phase separation methods. While these methods have increased the contact area and improved output performance to some extent, they also have significant limitations. First, the aforementioned micro / nano fabrication techniques typically rely on expensive equipment (such as photolithography machines and reactive ion etching machines) and complex processes, resulting in long preparation cycles and high costs, which are not conducive to large-scale industrialization. Second, some surface microstructures are prone to wear, collapse, or peeling during long-term repeated contact-separation processes, leading to a decrease in device stability and lifespan. In addition, some studies have attempted to improve dielectric properties and charge storage capacity by doping the friction layer material with nanofillers that have high dielectric constants or high charge trapping capabilities. However, this method often requires solving the problem of filler dispersion in the polymer matrix, and the filler is embedded inside the matrix, limiting its effect on improving the surface contact state.

[0006] Therefore, how to develop a friction interface optimization scheme that is simple in process, low in cost, can be mass-produced, and can simultaneously achieve high output performance and good mechanical stability remains a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a triboelectric nanogenerator and its preparation method. By constructing a single-layer dense SiO2 microsphere insertion layer on the surface of a PDMS triboelectric layer, the microstructure of the triboelectric interface is optimized in a simple, controllable, and low-cost manner, significantly improving the output performance and mechanical stability of the TENG.

[0008] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0009] A triboelectric nanogenerator, operating in a vertical contact-separation mode, comprises, from top to bottom:

[0010] Top electrode;

[0011] A positive friction layer, wherein the positive friction layer is a PET film;

[0012] A support structure is set around the electrode to maintain the spacing between the positive friction layer and the negative friction layer;

[0013] The negative friction layer is a PDMS composite film, and a single-layer dense insertion layer formed by monodisperse SiO2 microspheres is attached to the surface of the PDMS composite film.

[0014] Bottom electrode.

[0015] Furthermore, both the top and bottom electrodes are copper foils; the supporting structure material is elastic sponge.

[0016] Furthermore, the particle content of SiO2 microspheres per unit area on the surface of the monolayer dense insertion layer is 0.17~0.31 particles / μm. 2 .

[0017] Furthermore, the thickness of the positive friction layer is 0.02-0.05 mm, the thickness of the negative friction layer is 0.04-0.08 mm, the diameter of the SiO2 microspheres is 0.5-3 μm, and the spacing between the positive friction layer and the negative friction layer is 0.5-2 mm.

[0018] A method for preparing the triboelectric nanogenerator includes the following steps:

[0019] The PDMS prepolymer and curing agent are mixed, and then stirred and degassed to obtain a PDMS solution.

[0020] Monodisperse SiO2 microspheres were added to anhydrous ethanol, and after stirring and ultrasonic treatment, a uniform suspension of SiO2 microspheres was obtained.

[0021] On the substrate, the PDMS solution is first spin-coated, and then SiO2 microsphere suspension is spin-coated on the surface of the uncured PDMS film.

[0022] Heating and curing form a PDMS composite film with a single layer of dense SiO2 microspheres firmly attached to the surface. The PDMS composite film is a negative friction layer.

[0023] The negative friction layer, positive friction layer, electrode, and support structure are assembled in sequence to obtain a triboelectric nanogenerator.

[0024] Furthermore, the mass ratio of the PDMS prepolymer to the curing agent is 5:1 to 15:1; the stirring time is 20-60 minutes, and the degassing time is 10-30 minutes.

[0025] Furthermore, the mass fraction of the SiO2 microsphere suspension is 1-15 wt%.

[0026] Furthermore, the spin coating speed of the PDMS solution is 1000-2500 rpm, and the time is 20-60 seconds; the spin coating speed of the SiO2 microsphere suspension is 800-2000 rpm, and the time is 5-30 seconds.

[0027] Furthermore, the heat curing is carried out at 60-120°C for 1-4 hours.

[0028] Furthermore, the dispersion treatment includes stirring and / or ultrasonic treatment.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. The triboelectric nanogenerator and its fabrication method described in this invention significantly increase the effective contact area of ​​the triboelectric interface by constructing a monolayer dense SiO2 microsphere insertion layer. This invention employs a two-step spin-coating method to introduce monodisperse SiO2 microspheres onto the surface of uncured PDMS. Utilizing the rapid evaporation of the solvent and the surface self-assembly behavior of the microspheres, a micron-scale array of spherical protrusions is formed. This microstructure transforms the contact between the positive and negative triboelectric layers from a traditional "surface-to-surface" contact to a "surface-to-multipoint" contact, changing the contact mode from macroscopic planar contact to microscopic point array contact, thus significantly increasing the effective contact area. Based on the fundamental principle of contact electrification, the increased contact area directly leads to an increase in the amount of triboelectric charge generated, thereby laying the structural foundation for enhanced device output performance.

[0031] 2. The triboelectric nanogenerator and its fabrication method described in this invention utilize the charge-trapping ability and dielectric properties of SiO2 microspheres to significantly enhance the interfacial charge density and suppress charge dissipation. SiO2 material itself possesses a high dielectric constant and excellent charge storage capacity, enabling it to act as a charge-trapping center during contact electrification, locally enriching the charge generated by friction in the top region of the microspheres. Simultaneously, the microscopic geometric structure formed by the SiO2 microspheres on the PDMS surface leads to an uneven distribution of the interfacial electric field, resulting in a gradient potential effect. This effect effectively suppresses the dissipation of accumulated charge into the air or its migration into the material interior, allowing more charge to be retained and participate in the electrostatic induction process. This dual enhancement mechanism of charge trapping and charge retention results in a surface charge density in the TENG device of this invention that is significantly higher than that of conventional flat or simply doped triboelectric layers.

[0032] 3. The triboelectric nanogenerator and its preparation method described in this invention utilize the high hardness of SiO2 microspheres to endow the composite friction layer with excellent mechanical durability. Compared with microstructures formed by direct etching on polymer surfaces, inorganic SiO2 microspheres exhibit higher hardness and wear resistance. During long-term contact-separation cycles, the SiO2 microspheres can resist mechanical wear during friction, maintaining the integrity of the microstructure and thus ensuring the long-term stability of the device's output performance. Experiments show that the TENG device prepared by this invention does not exhibit significant performance degradation after tens of thousands of operating cycles, demonstrating good operational reliability.

[0033] 4. The triboelectric nanogenerator and its fabrication method described in this invention utilize the effect of SiO2 microsphere suspension concentration on device output performance. It was found that within an appropriate concentration range (especially around 5 wt%), a microsphere distribution closest to an ideal monolayer close packing can be formed on the PDMS surface. Under these optimized conditions, the open-circuit voltage of the TENG reaches 191 V, the short-circuit current reaches 3.54 μA, and the transferred charge reaches 62.8 nC. Compared with a comparative example using pure PDMS as the negative triboelectric layer, the above performance indicators are improved to 269%, 255%, and 262% of the latter, respectively, demonstrating a highly significant improvement. Compared with a comparative example where SiO2 microspheres are doped inside PDMS, the output performance of this invention also shows a significant advantage, fully demonstrating the superiority of the surface-inserted layer structure over the internally doped structure.

[0034] 5. The triboelectric nanogenerator and its fabrication method described in this invention employ a two-step spin-coating method that requires no expensive equipment such as photolithography or etching; all operations can be completed under conventional laboratory conditions. By adjusting process parameters such as spin-coating speed and solution concentration, the arrangement density and uniformity of SiO2 microspheres can be easily controlled. Compared with traditional micro / nano fabrication technologies, the method of this invention has a shorter process flow, lower raw material costs, and lower requirements for equipment and environment, showing good prospects for industrial application. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are some embodiments of the present invention. For those skilled in the art, it is obvious that other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the triboelectric nanogenerator described in this invention.

[0037] Figure 2 SEM image of the microstructure of the insertion layer formed on the PDMS surface by SiO2 microspheres.

[0038] Figure 3 The image shows a surface SEM image of a composite film formed by SiO2 microspheres doped inside PDMS.

[0039] Figure 4 This is a schematic diagram illustrating the working principle of the triboelectric nanogenerator of the present invention.

[0040] Figure 5 The graph shows a comparison of the open-circuit voltage, short-circuit current, and transferred charge performance of the examples and comparative examples.

[0041] Figure 6The output performance results for this example are shown under different operating frequencies and different loads. Detailed Implementation

[0042] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0044] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0045] like Figure 1As shown, the triboelectric nanogenerator of this invention operates in a vertical contact-separation mode. Its overall structure, from top to bottom, includes: a top electrode, a positive friction layer, a support structure, a negative friction layer, and a bottom electrode. The top electrode is made of copper foil with a thickness of approximately 0.03-0.05 mm, exhibiting good conductivity and flexibility. The positive friction layer, attached to the lower surface of the top electrode, is made of flexible, transparent polyethylene terephthalate (PET) film. According to the triboelectric series, PET easily loses electrons and becomes positively charged during contact electrification. The support structure is located around the perimeter of the electrode and is made of a highly elastic sponge material with certain elasticity and resilience. Its function is to maintain the initial distance between the positive and negative friction layers when no external force is applied. The negative friction layer is an improvement of this invention; it is a PDMS film with a composite structure. Specifically, it consists of a single-layer dense intercalation layer formed by monodisperse SiO2 microspheres firmly attached to the surface of a PDMS substrate. The bottom electrode, attached to the lower surface of the negative friction layer, is also made of copper foil. The height of the support structure determines the initial spacing between the positive and negative friction layers, which is controlled within the range of approximately 0.5-2 mm in this embodiment. When subjected to external mechanical action, the positive and negative friction layers come into contact, generating surface charge through friction. When the external force is released, the elastic restoring force of the support structure separates the two friction layers, thereby driving electrons to flow in the external circuit. The particle content of SiO2 microspheres per unit area on the surface of the monolayer dense insertion layer is 0.17~0.31 particles / μm. 2 .

[0046] The preparation method of the present invention and the performance of the obtained product are described in detail through multiple embodiments and comparative examples.

[0047] Example 1

[0048] Example 1 describes a method for preparing the triboelectric nanogenerator, comprising the following steps:

[0049] S01: The PDMS prepolymer and curing agent are mixed, and after stirring and degassing, a PDMS solution is obtained, specifically:

[0050] Weigh out Corning Sylgard 184 PDMS prepolymer and its matching curing agent, and mix them at a mass ratio of 10:1. At room temperature, place the mixture on a magnetic stirrer and stir at 300 rpm for 30 minutes to ensure thorough mixing. Then, place the mixture in a vacuum drying oven and degas for 15 minutes to obtain a clear, bubble-free PDMS prepolymer solution.

[0051] S02: Preparation of monodisperse SiO2 micron-sized sphere suspension.

[0052] Weigh monodisperse SiO2 microspheres with an average diameter of 1 μm and slowly add them to anhydrous ethanol to prepare a 1 wt% mixture. Stir the mixture magnetically for 30 minutes, then sonicate it for 10 minutes to fully disperse the microspheres and obtain a homogeneous and stable suspension.

[0053] S03: Preparation of negative friction layer (PDMS / SiO2 composite film).

[0054] A clean glass substrate is fixed on a spin coater. First, an appropriate amount of PDMS prepolymer solution is added, and the substrate is spin-coated at 1500 rpm for 30 seconds to form a uniform liquid film. After spin-coating, the next step is to add 1 wt% of the above-mentioned SiO2 suspension and spin-coat at 1200 rpm for 10 seconds. The spin-coated substrate is then placed in an 80°C oven for curing for 2 hours. After curing, the substrate is allowed to cool naturally to room temperature, and the composite film is removed from the substrate to obtain the negative friction layer.

[0055] S04: Cut the negative friction layer into 15mm × 15mm square pieces. Similarly, cut 15mm × 15mm PET film as the positive friction layer, and 15mm × 15mm copper foil as the top and bottom electrodes. Cut four 15mm × 1mm × 1mm strips of high-elasticity sponge as a support structure. Attach the sponge strips to the four edges of the bottom electrode, and then place the negative friction layer (SiO2 side up) in the center of the bottom electrode. Attach the top electrode to the back of the positive friction layer, and then align and place this assembly on the sponge support structure, ensuring the distance between the positive and negative friction layers is approximately 1mm. This completes the device assembly.

[0056] Working principle as follows Figure 4 As shown. When PET and PDMS film come into contact with each other under external force, as... Figure 4 -i, According to the principle of contact electrification, the PET surface loses electrons and becomes positively charged, while the PDMS film surface gains electrons and becomes negatively charged. On one hand, during contact electrification, the SiO2 microspheres, acting as an intermediate intercalation layer, concentrate the generated charge in the top region of the spherical particles, enhancing the local charge density. Simultaneously, the uneven electric field distribution caused by the SiO2 microspheres effectively suppresses charge dissipation due to the resulting gradient potential. On the other hand, due to the difference in dielectric constant between SiO2 and PDMS, when charges are trapped at the interface between SiO2 and PDMS, the electrostatically induced charges redistribute to form a space charge region, thus preventing charge dissipation. After the external force is removed, the positive and negative friction layers begin to gradually separate, as... Figure 4As shown in -ii. At this time, a built-in electric field will be formed between the friction layers, generating a potential difference. Due to electrostatic induction, electrons generated on the copper electrode will be driven from the bottom electrode to the top electrode through the external circuit, thereby generating an electrical signal. When the positive and negative friction layers are completely separated, the potential difference reaches its maximum value, the charges of the positive and negative friction layers and the upper and lower electrodes reach equilibrium, and the electrical properties of the two electrodes return to a neutral state, as shown in -ii. Figure 4 As shown in -iii, no electrical signal is generated at this point. When the positive and negative friction layers approach each other again, the electrostatic balance of the system is disrupted, thereby inducing electrons to migrate from the top electrode to the bottom electrode, generating an electrical signal in the opposite direction to the previous one, such as... Figure 4 -iv is shown.

[0057] Example 2:

[0058] The preparation method of Example 2 is basically the same as that of Example 1, except that: in step S01, the mass ratio of PDMS prepolymer to curing agent is adjusted to 12:1; and in S02, the concentration of the SiO2 microsphere suspension is 5 wt%. In step S03, the spin-coating speed of the PDMS solution is adjusted to 2000 rpm for 20 seconds; and in step S04, the curing temperature is adjusted to 100℃ for 1.5 hours. The microstructure of the negative friction layer surface formed in Example 2 is as follows: Figure 2 Scanning electron microscopy (SEM) images show that SiO2 microspheres form a relatively ideal, dense monolayer arrangement on the PDMS surface. Image analysis and statistical analysis indicate that the particle content of SiO2 microspheres per unit area on the surface is approximately 0.20–0.25 particles / μm. 2 .

[0059] Example 3:

[0060] The preparation method of Example 3 is basically the same as that of Example 1, except that the concentration of the SiO2 microsphere suspension prepared in S02 is 15wt%. In step S03, the spin-coating speed of the PDMS solution is adjusted to 1000 rpm for 50 seconds; the spin-coating speed of the SiO2 suspension is adjusted to 800 rpm for 25 seconds. In Example 3, the negative friction layer exhibits multi-layer stacking of microspheres in some areas, which is a decrease compared to the proportion of a single-layer dense area in Example 2.

[0061] Comparative Example 1

[0062] Comparative Example 1 provides a triboelectric nanogenerator using a pure PDMS thin film as the negative friction layer. The preparation method is basically the same as that of Example 1, except that the steps involving SiO2 microspheres are completely omitted. That is, only the PDMS prepolymer solution is spin-coated onto a clean glass substrate and cured to obtain a pure PDMS thin film as the negative friction layer, while the other components and assembly method remain unchanged.

[0063] Comparative Example 2

[0064] Comparative Example 2 provides a triboelectric nanogenerator in which SiO2 microspheres are mixed inside PDMS to form a composite film as a negative friction layer. The preparation method is basically the same as in Example 1, except for the preparation method of the negative friction layer: the 5wt% SiO2 suspension prepared in the second step is mixed with the PDMS prepolymer solution prepared in the first step, and after stirring and degassing, it is directly spin-coated onto a glass substrate and cured to obtain a PDMS composite film doped with SiO2 microspheres. The surface microstructure of this film is as follows... Figure 3 As shown, very few microspheres are exposed on the surface; most are embedded within the PDMS. In Comparative Example 2, the PDMS / SiO2 composite friction layer prepared by the method has a SiO2 microsphere content of 1.2 x 10⁻⁶ particles per unit area on its surface. -2 ~5x10 -2 per μm².

[0065] Performance comparison between the examples and comparative examples:

[0066] 1. Comparison of microstructure characteristics of negative friction layers:

[0067] The surface of the negative friction layer prepared in Example 2 was observed by scanning electron microscopy, and the results are as follows: Figure 2 As shown in the image, SiO2 microspheres form a dense monolayer arrangement on the PDMS surface. The microspheres are tightly packed together without obvious aggregation or stacking. Image analysis software analysis indicates that the particle content per unit area is approximately 0.17–0.31 particles / μm. 2 .

[0068] The surface of the doped composite film prepared in Comparative Example 2 was observed by scanning electron microscopy, and the results are as follows: Figure 3 As shown in the figure, the number of exposed SiO2 microspheres on the surface is extremely small, with a particle content of only 1.2 x 10⁻⁶ per unit area. -2 ~5x10 -2 With a density of 1 microsphere per μm², most microspheres are coated with PDMS and cannot effectively participate in frictional contact.

[0069] 2. Electrical output performance test results

[0070] A linear motor was used to simulate external mechanical motion, driving the TENG devices prepared in the above embodiments and comparative examples at an operating frequency of 1-5Hz. The open-circuit voltage (Voc), short-circuit current (Isc), and transferred charge (Qsc) were measured using a Keithley 6514 electrometer. Each sample was tested five times, and the average value was taken as the final result.

[0071] Table 1. Comparison of electrical output performance of different embodiments and comparative examples

[0072] Sample number <![CDATA[SiO2 concentration (wt%)]]> Open-circuit voltage Voc (V) Short-circuit current Isc (μA) Transferred charge Qsc (nC) Comparative Example 1 0 (Pure PDMS) 71.8 1.39 24.5 Comparative Example 2 5 (Internal Doping) 79.0 1.56 27.9 Example 1 1 118.5 2.31 41.3 Example 2 5 191.0 3.54 62.8 Example 3 15 121.4 2.28 40.5

[0073] Figure 5 The diagram shows a comparison of the open-circuit voltage, short-circuit current, and transferred charge performance of Embodiment 2, Comparative Example 1, and Comparative Example 2 of the present invention. Comparative Example 1 shows that without SiO2 microspheres as an intermediate insertion layer, the TENG output has an open-circuit voltage (Voc) of 71.8 V and a short-circuit current (Isc) of 1.39 V. A, the transferred charge (Q) is 24.5 nC. Comparative Example 2 shows that doping SiO2 microspheres inside PDMS increases the open-circuit voltage, short-circuit current, and transferred charge of the TENG by 10%, 12%, and 14%, respectively, which is a slight improvement compared to the pure PDMS-based TENG. The electrical output performance of the TENG with the intermediate insertion layer is significantly enhanced. Example 2 shows that when the SiO2 microsphere solution concentration is 5 wt%, its output open-circuit voltage reaches 191 V and the short-circuit current is 3.54 nC. A, with a transferred charge of 63 nC, represents 269%, 255%, and 262% of the output performance of the comparative TENG, respectively. PDMS modified with SiO2 microspheres significantly alters the output performance of TENG. As the concentration of SiO2 microspheres increases, the output performance of TENG generally shows a trend of first increasing and then decreasing, reaching its optimal performance at a SiO2 microsphere solution concentration of 5 wt%.

[0074] Figure 6 This demonstrates Embodiment 2 of the present invention at frequencies of 1-5 Hz and 1 kHz. -1G Performance characterization graph under load. From Figure 5 In (a), it is clearly observed that the output performance of the TENG increases with the increase of the external stimulation frequency, which is more pronounced in the lower frequency range of 1-3 Hz. The reason for this is that the TENG's working mechanism is based on contact electrification and electrostatic induction. At lower external stimulation frequencies, the contact separation period of the positive and negative friction layers is longer, resulting in insufficient charge transfer caused by electrostatic induction. As the external stimulation frequency increases, the contact period of the positive and negative friction layers is shortened, increasing the amount of charge generated by contact electrification per unit time, thereby improving the TENG's output efficiency. However, when the contact frequency reaches a certain critical value of 5 Hz, the amount of transferred charge gradually approaches saturation, and at this point, increasing the contact frequency no longer significantly improves the TENG's electrical output performance.

[0075] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0076] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A triboelectric nanogenerator, operating in a vertical contact-separation mode, characterized in that, From top to bottom, they include: Top electrode; A positive friction layer, wherein the positive friction layer is a PET film; A support structure is set around the electrode to maintain the spacing between the positive friction layer and the negative friction layer; The negative friction layer is a PDMS composite film, and a single-layer dense insertion layer formed by monodisperse SiO2 microspheres is attached to the surface of the PDMS composite film. Bottom electrode.

2. The triboelectric nanogenerator according to claim 1, characterized in that, Both the top and bottom electrodes are made of copper foil; the supporting structure material is elastic sponge.

3. The triboelectric nanogenerator according to claim 1, characterized in that, The particle content of SiO2 microspheres per unit area on the surface of the monolayer dense insert layer is 0.17~0.31 particles / μm. 2 .

4. The triboelectric nanogenerator according to claim 1, characterized in that, The thickness of the positive friction layer is 0.02-0.05 mm, the thickness of the negative friction layer is 0.04-0.08 mm, the diameter of the SiO2 microspheres is 0.5-3 μm, and the spacing between the positive and negative friction layers is 0.5-2 mm.

5. A method for preparing a triboelectric nanogenerator as described in any one of claims 1-4, characterized in that, Includes the following steps: The PDMS prepolymer and curing agent are mixed, and then stirred and degassed to obtain a PDMS solution. Monodisperse SiO2 microspheres were added to anhydrous ethanol, and after stirring and ultrasonic treatment, a uniform suspension of SiO2 microspheres was obtained. On the substrate, the PDMS solution is first spin-coated, and then SiO2 microsphere suspension is spin-coated on the surface of the uncured PDMS film. Heating and curing form a PDMS composite film with a single layer of dense SiO2 microspheres firmly attached to the surface. The PDMS composite film is a negative friction layer. The negative friction layer, positive friction layer, electrode, and support structure are assembled in sequence to obtain a triboelectric nanogenerator.

6. The method for preparing a triboelectric nanogenerator according to claim 5, characterized in that, The mass ratio of the PDMS prepolymer to the curing agent is 5:1 to 15:1; the stirring time is 20-60 minutes, and the degassing time is 10-30 minutes.

7. The method for preparing a triboelectric nanogenerator according to claim 5, characterized in that, The mass fraction of the SiO2 microsphere suspension is 1-15 wt%.

8. The method for preparing a triboelectric nanogenerator according to claim 5, characterized in that, The spin coating speed for PDMS solution is 1000-2500 rpm, and the time is 20-60 seconds; the spin coating speed for SiO2 microsphere suspension is 800-2000 rpm, and the time is 5-30 seconds.

9. The method for preparing a triboelectric nanogenerator according to claim 5, characterized in that, The heat curing is carried out at 60-120℃ for 1-4 hours.

10. The method for preparing a triboelectric nanogenerator according to claim 5, characterized in that, The dispersion process includes stirring and / or ultrasonic treatment.

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