Preparation method of triboelectric-piezoelectric nano generator with hollow fiber structure

Abstract

The invention relates to a preparation method of a triboelectric-piezoelectric nano generator with a hollow fiber structure. The preparation method comprises the following steps: drying PVDF powder, TPU beads and PVP powder; adding the LMs into a mixed solvent of DMF (Dimethyl Formamide) and acetone, and completely dispersing the LMs; adding PVDF powder into the dispersion liquid to obtain a PVDF spinning solution; adding the PVP powder into absolute ethyl alcohol to obtain a PVP spinning solution; preparing a coaxial solid PVDF / LMs coated PVP nanofiber film by taking a PVDF spinning solution as a shell layer solution and a PVP spinning solution as a core layer solution; carrying out drying, soaking, heating, ultrasonic treatment and drying on the PVDF / LMs coated PVP nano-fiber thin film to obtain a hollow PVDF / LMs nano-fiber thin film; tPU beads are added into a mixed solvent of DMF and THF, and a TPU spinning solution is obtained; carrying out electrostatic spinning on the TPU spinning solution to obtain a TPU nanofiber film; and constructing the triboelectricity-piezoelectricity hybrid nano-generator by using the PVDF / LMs nano-fiber film and the TPU nano-fiber film. According to the invention, a piezoelectric material PVDF is used as one pole of a friction nano generator (TEGN), so that the friction electricity-piezoelectric effect is cooperated.

Description

TECHNICAL FIELD The application belongs to the technical field of triboelectric-piezoelectric nanogenerator, and particularly relates to a preparation method of a triboelectric-piezoelectric nanogenerator with a hollow fiber structure. BACKGROUND The existing triboelectric-piezoelectric hybrid nanogenerator (HNG) technology mostly adopts the physical stacking or separate packaging mode of TENG and PENG, which leads to the complication of the mechanical energy transmission path, and it is difficult to meet the needs of simple and lightweight flexible electronic devices. In addition, the conventional PVDF-based piezoelectric material has low beta phase crystallinity (usually < 60%) and limited polarization process, and is often internally modified by adding fillers, but the commonly used nano fillers mainly include ZnO nanosheets and nanowires, silver nanowires, MXene nanosheets, BaTiO3 nanofibers, graphene and carbon nanotubes, etc. The cost is high, the synthesis method is complex, and it is difficult to mass-produce. Secondly, in the existing triboelectric-piezoelectric hybrid nanogenerator (HNG), the friction layer mostly adopts dense film or micro-sized solid fiber structure, and the deformation freedom is limited, which leads to the piezoelectric effect only triggering in single deformation, and even difficult to trigger.

[0001] With the rapid development of Internet of Things, wearable electronic devices and distributed sensor networks, environmental energy harvesting technology has become a key direction to break through the limitations of traditional battery endurance and volume. Mechanical energy (such as human motion, wind energy, and vibration energy) is considered as an ideal energy source due to its wide existence, but its low frequency and non-steady-state characteristics pose high adaptability requirements on energy conversion devices. Traditional electromagnetic power generation technology is difficult to apply due to low efficiency at low frequency and bulky size, while the triboelectric nanogenerator (TENG) based on contact electrification and the piezoelectric nanogenerator (PENG) based on polarization effect have become the mainstream solution with high energy density and structural flexibility. However, single mechanism has significant shortcomings: TENG relies on contact separation efficiency and is easily disturbed by environmental humidity, and PENG has insufficient response to small deformation and relies on high-frequency excitation. In this context, exploring the synergistic mechanism of triboelectric and piezoelectric effects and building a composite nanogenerator to realize wide-frequency and high-efficiency energy harvesting have become an important research direction in the field.

[0002] The current research and development of triboelectric-piezoelectric hybrid generator (HNG) faces multi-dimensional technical bottlenecks. From the material level, the polarization efficiency of traditional piezoelectric materials is insufficient, resulting in low conversion sensitivity of low-frequency mechanical energy; the weak dielectric performance of friction materials further limits the improvement of surface charge density. From the perspective of structural design, the existing hybrid schemes mostly use physically stacked discrete devices, which leads to complex mechanical energy transmission path, significant interface energy loss, and volume redundancy that is difficult to meet the demand of flexible electronic ultra-thinning. In addition, the contradiction between device structure rigidity and insufficient deformation freedom makes it difficult for piezoelectric effect to dynamically couple with triboelectric effect, resulting in energy conversion efficiency far lower than the theoretical expectation. Although recent research attempts to optimize performance through nanostructure modification or material compounding, how to realize the integrated design of material polarization enhancement, interface charge cooperative transport and efficient coupling of mechanical deformation remains a core challenge to be broken through. SUMMARY The present application improves the prior art, that is, the technical problem to be solved by the present application is to provide a preparation method of a triboelectric-piezoelectric nanogenerator with a hollow fiber structure.

[0003] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: a preparation method of a triboelectric-piezoelectric nanogenerator with a hollow fiber structure, comprising the following steps: Step S1: dry PVDF powder, TPU beads and PVP powder to remove moisture; Step S2: add LMs to a mixed solvent of DMF and acetone, and ultrasonicate the solution to completely disperse the LMs; Step S3: add the dried PVDF powder to the LMs dispersion liquid in step S2 and heat and stir to obtain a PVDF spinning solution; Step S4: add the dried PVP powder to anhydrous ethanol and heat and stir to obtain a PVP spinning solution; Step S5: prepare a coaxial solid PVDF / LMs@PVP nanofiber film with the PVDF spinning solution as the shell layer solution and the PVP spinning solution as the core layer solution; Step S6: dry the PVDF / LMs@PVP nanofiber film, then soak it in deionized water, heat it in a water bath, change the water and put it in an ultrasonic machine, finally take it out and dry the moisture to obtain a hollow PVDF / LMs nanofiber film; Step S7: add the dried TPU beads to a mixed solvent of DMF and THF and heat and stir to obtain a TPU spinning solution; Step S8: electrospun the TPU spinning solution to obtain a TPU nanofiber film with uniform fibers; Step S9: cutting the hollow PVDF / LMs nanofiber membrane and the TPU nanofiber membrane into a block shape, then using a PTFE film as a substrate, and fixing a piece of PTFE film with the same size as the PVDF / LMs nanofiber membrane and the TPU nanofiber membrane at the center position of the substrate; then, sequentially placing the wire, copper electrode sheet and PVDF / LMs nanofiber membrane on the PTFE film at the middle position of the substrate to construct one pole of the triboelectric-piezoelectric hybrid nanogenerator; in the same way, stacking the TPU nanofiber membrane to construct the other pole of the triboelectric-piezoelectric hybrid nanogenerator; finally, connecting the two poles with a sponge to prepare the triboelectric-piezoelectric nanogenerator.

[0004] Further, the specific steps of step S1 include: drying the PVDF powder, TPU beads and PVP powder in an oven at 60°C for 6 hours.

[0005] Further, the specific steps of step S2 include: adding 0.036 g of LMs to 8.2 g of a mixed solvent of DMF and acetone, wherein the mass ratio of DMF to acetone is 3:2, and ultrasonically treating the solution for 2 hours to completely disperse the LMs.

[0006] Further, the specific steps of step S3 include: adding 1.8 g of dried PVDF powder to the LMs dispersion solution in step S2, and performing oil bath heating and stirring at 60°C, to obtain a 18 wt.% PVDF spinning solution with a 2 wt.% LMs content after 4 hours.

[0007] Further, the specific steps of step S4 include: adding 1.4 g of dried PVP powder to 8.6 g of anhydrous ethanol, and performing oil bath heating and stirring at 60°C, to obtain a 14 wt.% PVP spinning solution after 4 hours.

[0008] Further, the specific steps of step S5 include: using the PVDF spinning solution with 2 wt.% LMs as the shell layer solution, and using the 14 wt.% PVP spinning solution as the core layer solution.

[0009] Further, the coaxial solid PVDF / LMs@PVP nanofiber membrane is prepared using a shell layer solution and a core layer solution at a flow rate ratio of 5:3, a shell layer solution push speed of 1 mL / h, a core layer solution push speed of 0.6 mL / h, a spinning voltage of 12 kV, a collection speed of 300 rpm, a collection distance of 15 cm, and a 22G / 17G coaxial needle.

[0010] Further, the specific steps of the step S6 include: placing the PVDF / LMs@PVP nanofiber film into an oven for 8 hours, then cutting into blocks and soaking in ionized water, heating in a water bath at 40 DEG C for 2 hours, changing the water and placing in an ultrasonic machine for half an hour, finally taking out and drying in an oven to obtain the hollow PVDF / LMs nanofiber film.

[0011] Further, the specific steps of the step S7 include: adding 2 g of the dried TPU beads into 8 g of a mixed solvent of DMF and THF, the mass ratio of DMF and THF being 1:2, and performing oil bath heating and stirring at 60 DEG C, to obtain a 20wt.% TPU spinning solution after 6 h.

[0012] Further, the specific steps of the step S8 include: selecting a 20 G needle head to perform single-needle head electrospinning on the TPU spinning solution, and the electrospinning process parameters are as follows: precursor solution concentration 20wt.%, spinning voltage 10 kV, temperature 25 DEG C, solution flow rate 1 mL / h, drum collection rotation speed 300 rpm, and collection distance 15 cm, to obtain a TPU nanofiber film with uniform fibers.

[0013] Compared with the prior art, the present application has the following effects: (1) The filler gallium-based liquid metal (LMs) selected by the present application has unique fluidity, high electrical conductivity, low toxicity, good chemical stability, and relatively low price; the gallium-based liquid metal can not only maintain a continuous conductive network during mechanical deformation, but also adapt to the microstructure changes of the PVDF fiber film through its fluidity, effectively avoiding performance degradation caused by stress concentration, thereby ensuring excellent electrical output performance; (2) The two electrodes of the present application are both nanofiber films prepared by electrospinning process, and have larger specific surface area, so that greater triboelectric effect is generated when the two electrodes are in contact and separated, thereby improving the overall electrical output performance; (3) The present application constructs a hollow structure of nanofiber, which increases the deformation space of the fiber to enhance the piezoelectric effect, and increases the internal specific surface area, thereby synergizing with the gallium-based liquid metal (LMs) for secondary polarization to improve the triboelectric charge generation capacity. BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a preparation process schematic diagram of an embodiment of the present application; Figure 2 : (a) SEM image of the surface of the PLPE fiber film; (b) SEM image of the fiber cross section; (c) magnified image of the cross section of a single fiber; (d) EDS energy spectrum analysis image of each element; Figure 3 is a structure schematic diagram of a triboelectric-piezoelectric nanogenerator in an embodiment of the present application; Figure 4 (a) FTIR spectra of pure PVDF, PVDF@2wt.%LMs (PL2), PLP, and PLPE fiber membranes; (b) Open-circuit voltages of nanogenerators assembled with TPU from pure PVDF, PL2, PLP, and PLPE, respectively. Figure 5 The following are the application diagrams of the present invention in human body signal monitoring and wearable self-powered devices: (a1) Signals when the arm is bent at different angles and (a2) The generated current lights up the LED light; (b) Electrical signals generated when the arm is squeezed while walking; (c) Electrical signals generated when squatting; (d) Electrical signals generated when clenching a fist; (e1) The HNG is assembled on the surface of clothing, and the LED light will light up during nighttime running and exercise, and its corresponding electrical signal curve (e2).

[0014] In the picture: 1-Substrate; 2-PTFE film; 3-Wire; 4-Copper electrode sheet; 5-PVDF / LMs nanofiber film; 6-TPU nanofiber film; 7-Sponge. Detailed implementation method: The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0015] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to 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 this invention.

[0016] like Figure 1 As shown, this invention discloses a method for fabricating a triboelectric-piezoelectric nanogenerator with a hollow fiber structure, addressing the problems of structural complexity and increased interfacial resistance caused by the physical superposition of existing hybrid nanogenerators. Simultaneously, it introduces special liquid metal nanofillers and a hollow structure that provides greater deformation space, improving the material polarization process and increasing the content of the polar β-phase molecules, thereby enhancing the triboelectric and piezoelectric effects and improving the electrical output performance of the nanogenerator. Specifically, it includes the following steps: Step S1: Dry PVDF (polyvinylidene fluoride) powder, TPU (thermoplastic polyurethane) beads and PVP (polyvinylpyrrolidone) powder in an oven at 60°C for 6 hours to remove moisture; Step S2: Add 0.036g of LMs (gallium-based liquid metals) to a mixed solvent of 8.2g of DMF (N,N-dimethylformamide) and acetone, wherein the mass ratio of DMF to acetone is 3:2, and sonicate the solution for 2 hours to completely disperse the LMs. Step S3: Add 1.8g of dried PVDF powder to the LMs dispersion in step S2, and heat and stir in an oil bath at 60°C for 4 hours to obtain a PVDF spinning solution with 2 wt.% LMs content (relative to PVDF). Step S4: Add 1.4g of dried PVP powder to 8.6g of anhydrous ethanol, heat and stir in an oil bath at 60℃ for 4h to obtain a 14 wt.% PVP spinning solution; Step S5: Using a PVDF spinning solution with 2 wt.% LMs added as the shell solution and a PVP spinning solution with 14 wt.% added as the core solution, a shell solution to core solution flow rate ratio of 5:3 was adopted, i.e., the shell solution push rate was 1 mL / h and the core solution push rate was 0.6 mL / h. Under the conditions of a spinning voltage of 12 kV, a collection speed of 300 rpm and a collection distance of 15 cm, a 22 G / 17 G coaxial needle was used to prepare a coaxial solid PVDF / LMs@PVP nanofiber film (PLP). Step S6: After placing the PVDF / LMs@PVP nanofiber film (PLP) in an oven for 8 hours, remove it, cut it into small pieces, soak it in deionized water, heat it in a water bath at 40°C for 2 hours, change the water and place it in an ultrasonic machine for half an hour, and finally remove it and place it in an oven to dry the moisture to obtain hollow PVDF / LMs nanofiber film (PLPE). Figure 2 (a) is a surface morphology diagram of the fibrous membrane. Figure 2 (b) is a cross-sectional morphology diagram of the fiber. Figure 2 (c) is Figure 2 (b) is a magnified view of a single fiber, from which the hollow structure of the fiber can be clearly observed.

[0017] Step S7: Add 2 g of dried TPU beads to a mixed solvent of 8 g DMF and THF (tetrahydrofuran), with a mass ratio of DMF to THF of 1:2. Heat and stir in an oil bath at 60°C for 6 h to obtain a 20 wt.% TPU spinning solution. Step S8: Use a 20 G needle to perform single-needle electrospinning on the TPU spinning solution. The electrospinning process parameters are: precursor solution solubility 20 wt.%, spinning voltage 10 kV, temperature 25℃, solution flow rate 1 mL / h, roller collection speed 300 rpm, collection distance 15 cm, to obtain a TPU nanofiber film with uniform fibers. Step S9: Cut hollow PVDF / LMs nanofiber films (PLPE) and TPU nanofiber films into 2x2 (cm) blocks. Then, select a 0.5 mm thick commercial PTFE (polytetrafluoroethylene) film as the substrate, and tightly adhere a PTFE film (2x2 (cm) of the same size as the PVDF / LMs and TPU nanofiber films to the center of the substrate. Next, sequentially stack the wires, copper electrode sheet, and PVDF / LMs nanofiber film onto the PTFE film in the center of the substrate, thus constructing one electrode (negative electrode) of the triboelectric-piezoelectric hybrid nanogenerator. Stack the TPU nanofiber film in the same manner to construct the other electrode (positive electrode) of the triboelectric-piezoelectric hybrid nanogenerator. Finally, connect the two electrodes using a 40 ppi, 1 cm high sponge to fabricate the triboelectric-piezoelectric nanogenerator (HNG). Figure 3 As shown.

[0018] In this embodiment, step S10 is also included, which tests the electrical output performance of the triboelectric-piezoelectric nanogenerator (HNG) prepared in step S9: Figure 4(a) shows that pure PVDF, PVDF@2wt.% LMs (PL2), PLP, and PLPE fiber films are assembled with TPU to form nanogenerators. The open circuit voltage of the nanogenerators under a contact pressure of 20N and a contact frequency of 1Hz is measured. It can be observed that the open circuit voltage of the PLPE-TPU based nanogenerator is up to 272V. The hollow structure of the surface fibers improves the output voltage.

[0019] In this embodiment, the PLPE-TPU-based nanogenerator has the characteristics of being lightweight, fast-responding, flexible, and having excellent stability, and can be widely used in the field of self-powered wearable devices. Figure 5 The invention demonstrates its potential as a self-powered sensor in detecting human motion signals, such as arm bending, walking, squatting, fist clenching, and integrating it into clothing to light up LEDs. The stability and versatility shown in these applications indicate that the PLPE-TPU-based nanogenerator self-powered sensor of this invention has strong application potential in the fields of human motion and wearable devices.

[0020] In this embodiment, existing HNGs mostly adopt a physical superposition design of TENG and PENG, which leads to increased device size, increased interfacial contact resistance, and energy dissipation during mechanical energy transfer. In contrast, this invention constructs an integrated triboelectric-piezoelectric hybrid nanogenerator (HNG) by using PVDF as the negative electrode and TPU as the positive electrode, thereby achieving in-situ coupling of triboelectric and piezoelectric effects, eliminating interfacial impedance, and improving the mechanical energy to electrical energy conversion efficiency.

[0021] In this embodiment, the β-phase content of conventional piezoelectric material PVDF is relatively low, and the nanofillers commonly used for internal polarization are difficult to mass-produce due to their high cost and complex synthesis methods. However, this invention uses gallium-based liquid metal doping combined with electrospinning to simultaneously induce β-phase crystallization during PVDF fiber formation and achieve secondary polarization through the dielectric regulation effect of liquid metal, thereby improving piezoelectric output.

[0022] In this embodiment, the solid friction layer structure struggles to balance the need for high contact area with the degree of freedom of deformation. While achieving triboelectricity and piezoelectricity, the flexibility of ordinary solid fibers makes it difficult for them to undergo significant deformation, resulting in a weak piezoelectric effect. This invention, however, constructs PVDF nanofibers with hollow channels. This increases the degree of freedom of deformation to enhance the piezoelectric response, and also increases surface roughness and active site density through topological structure control, synergistically improving the triboelectric charge generation capability and significantly enhancing the overall electrical performance output.

[0023] If this invention discloses or relates to mutually fixedly connected components or structural parts, then unless otherwise stated, a fixed connection can be understood as: a detachable fixed connection (e.g., using bolts or screws) or a non-detachable fixed connection (e.g., riveting, welding). Of course, mutually fixed connections can also be replaced by an integral structure (e.g., manufactured using a casting process) (except where it is obviously impossible to use an integral molding process).

[0024] In addition, unless otherwise stated, the terms used in any of the technical solutions disclosed in this invention to indicate positional relationships or shapes include states or shapes that are similar to, close to, or approximate with those states or shapes.

[0025] Any component provided by this invention can be assembled from multiple individual components or can be a single component manufactured by a one-piece molding process.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications can still be made to the specific implementation of the present invention or equivalent substitutions can be made to some technical features without departing from the spirit of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the technical solutions claimed in the present invention.

Claims

1. A method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure, characterized in that: Includes the following steps: Step S1: Dry the PVDF powder, TPU beads and PVP powder to remove moisture; Step S2: Add LMs to a mixed solvent of DMF and acetone, and sonicate the solution to completely disperse the LMs; Step S3: Add the dried PVDF powder to the LMs dispersion in step S2, and heat and stir to obtain the PVDF spinning solution; Step S4: Add the dried PVP powder to anhydrous ethanol, heat and stir to obtain PVP spinning solution; Step S5: Using PVDF spinning solution as the shell layer solution and PVP spinning solution as the core layer solution, prepare coaxial solid PVDF / LMs@PVP nanofiber films; Step S6: Dry the PVDF / LMs@PVP nanofiber film, then soak it in deionized water, heat it in a water bath, change the water and put it in an ultrasonic machine, and finally take it out and dry the water to obtain a hollow PVDF / LMs nanofiber film. Step S7: Add the dried TPU beads to a mixed solvent of DMF and THF, and heat and stir to obtain a TPU spinning solution; Step S8: Electrospin the TPU spinning solution to obtain a uniform TPU nanofiber film; Step S9: Cut the hollow PVDF / LMs nanofiber film and TPU nanofiber film into block shapes. Then, use a PTFE film as a substrate and fix a PTFE film with the same specifications as the PVDF / LMs nanofiber film and TPU nanofiber film at the center of the substrate. Next, sequentially stack the wires, copper electrode sheet, and PVDF / LMs nanofiber film on the PTFE film in the middle of the substrate to construct one pole of the triboelectric-piezoelectric hybrid nanogenerator. Stack the TPU nanofiber film in the same way to construct the other pole of the triboelectric-piezoelectric hybrid nanogenerator. Finally, connect the two poles with a sponge to prepare the triboelectric-piezoelectric nanogenerator.

2. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 1, characterized in that: The specific steps of step S1 include: drying PVDF powder, TPU beads and PVP powder in an oven at 60°C for 6 hours.

3. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 1, characterized in that: The specific steps of step S2 include: adding 0.036g of LMs to a mixed solvent of 8.2g of DMF and acetone, wherein the mass ratio of DMF to acetone is 3:2, and sonicating the solution for 2 hours to completely disperse the LMs.

4. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 3, characterized in that: The specific steps of step S3 include: adding 1.8 g of dried PVDF powder to the LMs dispersion in step S2, and heating and stirring in an oil bath at 60°C for 4 h to obtain a PVDF spinning solution with a 2 wt.% LMs content of 18 wt.% 5. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 4, characterized in that: The specific steps of step S4 include: adding 1.4g of dried PVP powder to 8.6g of anhydrous ethanol, heating and stirring in an oil bath at 60°C, and obtaining a 14 wt.% PVP spinning solution after 4 hours.

6. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 5, characterized in that: The specific steps of step S5 include: using a PVDF spinning solution with 2 wt.% LMs added as the shell layer solution and a PVDF spinning solution with 14 wt.% PVP added as the core layer solution.

7. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 1 or 6, characterized in that: Coaxial solid PVDF / LMs@PVP nanofiber films were prepared using a shell solution to core solution flow rate ratio of 5:3, a shell solution push rate of 1 mL / h, a core solution push rate of 0.6 mL / h, a spinning voltage of 12 kV, a collection speed of 300 rpm, and a collection distance of 15 cm, with a 22 G / 17 G coaxial needle.

8. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 1, characterized in that: The specific steps of step S6 include: placing the PVDF / LMs@PVP nanofiber film in an oven for 8 hours, then taking it out, cutting it into blocks, soaking it in deionized water, heating it in a water bath at 40°C for 2 hours, changing the water and placing it in an ultrasonic machine for half an hour, and finally taking it out and placing it in an oven to dry the moisture to obtain a hollow PVDF / LMs nanofiber film.

9. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 1, characterized in that: The specific steps of step S7 include: adding 2 g of dried TPU beads to a mixed solvent of 8 g DMF and THF, with a mass ratio of DMF to THF of 1:2, heating and stirring in an oil bath at 60°C, and obtaining a 20 wt.% TPU spinning solution after 6 h.

10. The method for preparing a triboelectric-piezoelectric nanogenerator with a hollow fiber structure according to claim 1, characterized in that: The specific steps of step S8 include: using a 20 G needle to perform single-needle electrospinning on the TPU spinning solution. The electrospinning process parameters are: precursor solution solubility 20 wt.%, spinning voltage 10 kV, temperature 25℃, solution flow rate 1 mL / h, roller collection speed 300 rpm, collection distance 15 cm, to obtain a TPU nanofiber film with uniform fibers.

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