Friction nanometer generator for collecting low-frequency wave energy and power generation method thereof

Abstract

The invention is suitable for the technical field of ocean power generation, and provides a friction nano-generator for collecting low-frequency wave energy and a power generation method thereof. According to the invention, the electrode distribution in the friction nanometer generator (TENG) is optimized, and the flowing direction of the current is fixed, so that the design of a power management circuit is simplified. Meanwhile, TENG aims at reducing friction loss, a friction structure adopts a solid-solid contact separation mode, and a solid-solid sliding mode is not adopted. In addition, according to the buoy using the device, rolling balls are distributed in a packaging shell module of the buoy to trigger an array composed of TENG to work, and all-directional collection of sea wave energy is achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of ocean energy power generation, and in particular, relates to a friction nanogenerator for collecting low-frequency wave energy and a power generation method thereof. Background Art

[0002] Compared with electromagnetic generators (EMGs), triboelectric nanogenerators (TENGs) can more efficiently convert various forms of tiny mechanical energy into electrical energy. Due to the unpredictability of ocean waves, an ideal wave energy harvesting device must be durable, highly sensitive, able to respond to low-frequency and low-amplitude waves, and equipped with power management circuits. In addition, the device should be able to capture wave energy from any direction in order to have practical application value in natural marine environments.

[0003] In the prior art, one strategy is to convert low-frequency wave motion into high-frequency motion that can be efficiently utilized by TENG through mechanical design, thereby achieving the capture of low-frequency wave energy. However, this power generation scheme may be relatively complex in terms of structure and power management circuit. Another strategy is to combine EMGs with TENG to collect wave energy. Such a combination can make up for the problem of insufficient energy output of TENG under low-frequency conditions. However, due to the different working principles of EMGs and TENG, suitable power management circuits are required to couple their outputs, which requires precise coordination between the two, making the structure of the device more complicated. Therefore, there is an urgent need to develop a new type of TENG that can capture low-frequency wave energy in all directions, simplify the design of power management circuits, and extend the service life of the device to adapt to the changing marine environment, and the prior art has shortcomings. Summary of the invention

[0004] The purpose of this application is to provide a friction nanogenerator for collecting low-frequency wave energy and a power generation method thereof, aiming to solve the technical problems of complex generator structure and power management circuit design when collecting low-frequency wave energy through structural improvements on the friction nanogenerator.

[0005] On the one hand, the present application provides a friction nanogenerator for collecting low-frequency wave energy, which comprises, from the outside to the inside, an outer frame (6), an internal support frame (7), a middle electrode (8) and a friction layer (9);

[0006] The outer frame (6) is composed of two pieces of elastic material bent into curved surfaces, and the guide planes of the two pieces are fitted to each other to form a double-layer arched structure with an olive-shaped through hole; both ends of the olive-shaped through hole are flat surfaces;

[0007] The internal support frame (7) is supported in the concave surface of the elastic material, and comprises a support plate which is parallel to the guide plane and has an area smaller than that of the guide plane, and a support beam connected between the support plate and the concave surface; the side edge of the support plate in the width direction is in contact with the unstretched concave surface;

[0008] The middle electrode (8) comprises an insulating plate and two first electrodes (Cu-1); the insulating plate is located on the guide plane, and its side in the length direction is fixedly connected to the outer frame (6); the two first electrodes (Cu-1) are respectively attached to two surfaces of the insulating plate;

[0009] The friction layer (9) is arranged on a surface of the support plate pointing to the middle electrode (8), and corresponds in space to the closest first electrode (Cu-1); the friction layer (9) comprises a third electrode (Cu-3) and a composite layer which are insulated from each other; the composite layer comprises an adhesion layer, a second electrode (Cu-2) and a rectangular friction material which are stacked in sequence from the support plate to the middle electrode (8); the adhesion layer stretches naturally when not subjected to pressure from the outer frame (6), so that the composite layer is closer to the corresponding first electrode (Cu-1) relative to the third electrode (Cu-3); a wire is provided between the third electrode (Cu-3) and the second electrode (Cu-2) to access a load.

[0010] Furthermore, the material of the internal support frame (7) is acrylic.

[0011] Furthermore, the first electrode (Cu-1), the second electrode (Cu-2) and the third electrode (Cu-3) are made of copper.

[0012] Furthermore, the material of the outer frame (6) is polyethylene terephthalate.

[0013] Furthermore, the outer frame (6) seals the olive-shaped through hole after reserving the connection line of the load.

[0014] Furthermore, the length of the support plate is consistent with the height of the olive-shaped through hole.

[0015] Furthermore, the support beam is vertically arranged to the support plate; the support beam is fixedly connected to the concave surface; and the number of the support beams is not less than two.

[0016] On the other hand, the present application also provides a method for generating electricity by collecting low-frequency wave energy, using a friction nanogenerator for collecting low-frequency wave energy as described in any of the above items; the method for generating electricity comprises:

[0017] s1. When the outer frame (6) is not squeezed and deformed, the first electrode (Cu-1) on the middle electrode (8) is separated from the rectangular friction material on the friction layer (9), and a negative charge remains on the surface of the rectangular friction material, while the first electrode (Cu-1) and the second electrode (Cu-2) have a positive charge;

[0018] s2. When an external force is applied to the outer frame (6), the elastic material of the outer frame (6) is deformed and squeezes the internal support frame (7) inward, so that the rectangular friction material on the internal support frame (7) contacts the first electrode (Cu-1) on the corresponding side of the middle electrode (8); at the same time, the adhesion layer is also compressed so that the third electrode (Cu-3) also contacts the first electrode (Cu-1); in the friction layer (9), the rectangular friction material contacts and rubs with the second electrode (Cu-2), so that the number of positive charges on the second electrode (Cu-2) is greater than that on the first electrode (Cu-1). Since the surface potential of the first electrode (Cu-1) is lower than that of the second electrode (Cu-2), the potential difference will induce the positive charge in the second electrode (Cu-2) to be transferred to the first electrode (Cu-1) through the external load and the third electrode (Cu-3); so that the external load generates current;

[0019] s3. When the external force is removed, the elasticity of the adhesive layer and the outer frame (6) will preferentially cause the first electrode (Cu-1) to separate from the third electrode (Cu-3), while the second electrode (Cu-2) remains in contact with the rectangular friction material; this action will cut off the original circuit and prevent the positive charge from returning from the first electrode (Cu-1) to the second electrode (Cu-2);

[0020] s4. When the rebound of the outer frame (6) further causes the first electrode (Cu-1) to separate from the rectangular friction material again and establish a potential difference, the positive charge will remain in the first electrode (Cu-1); this rapid increase in voltage will cause electrostatic breakdown of the edge air between the first electrode (Cu-1) and the second electrode (Cu-2) to form an ionized air channel (10); allowing the positive charge to be transferred back to the second electrode (Cu-2), thereby ultimately restoring the friction nanogenerator to the state of the first stage.

[0021] On the other hand, the present application also provides a self-generating buoy, comprising a waterproof and adaptive center of gravity shell (2), a light-emitting LED set and a supporting circuit; a plurality of friction nanogenerators (1) for collecting low-frequency wave energy as described in any of the above items are arranged in the sealed space of the shell (2); the planar end of the friction nanogenerator (1) is arranged perpendicular to the horizontal plane, and the arched narrow side edges are connected end to end to form a power generation unit array (4), and the convex surface of the outer frame (6) points to the center of the polygon of the power generation unit array (4); a sphere (3) is arranged in the central area of ​​the polygon, and the mass of the sphere (3) is arranged to ensure that the rolling energy of the sphere squeezes the friction nanogenerator (1) in the impact direction, so that the outer frame (6) undergoes deformation and generates electricity; the light-emitting LED serves as the load of the friction nanogenerator (1).

[0022] Furthermore, the number of the friction nanogenerators is set to 6.

[0023] This application simplifies the design of the power management circuit by optimizing the electrode distribution in the friction nanogenerator (TENG) and fixing the flow direction of the current. At the same time, the TENG in this application aims to reduce friction loss, and the friction structure adopts a solid-solid contact separation mode instead of a solid-solid sliding mode. The buoy is applied to place rolling balls in the internal space of the encapsulation shell module to trigger the array composed of TENGs to generate electricity, thereby realizing the all-round collection of wave energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of a buoy structure that uses the friction nanogenerator of the present application to generate electricity and drive LED light;

[0025] Figure 2 This is a schematic diagram of the overall structure of the friction nanogenerator of the present application;

[0026] Figure 3 This is a diagram showing the power generation working principle of the friction nanogenerator of the present application;

[0027] Figure 4 This is a schematic diagram of the omnidirectional test of the friction nanogenerator of the present application after forming a six-unit array;

[0028] Figure 5 This is a performance test diagram of the friction nanogenerator of the present application under low-frequency excitation;

[0029] Figure 6 It is a test diagram of using the friction nanogenerator of the present application to supply energy to capacitors of different capacities;

[0030] Figure 7 It is a diagrammatic representation of the state of a buoy using the friction nanogenerator of the present application when used in an actual marine environment. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0032] The specific implementation of this application is described in detail below in conjunction with specific embodiments:

[0033] Embodiment 1:

[0034] Figure 2 The structure of the friction nanogenerator (TENG) for collecting low-frequency wave energy provided in the first embodiment of the present application is shown. For the sake of convenience, only the part related to the embodiment of the present application is shown, which is described in detail as follows:

[0035] On the one hand, if Figure 2 As shown, the present application provides a friction nanogenerator for collecting low-frequency wave energy, which includes an outer frame 6, an internal support frame 7, a middle electrode 8 and a friction layer 9 from the outside to the inside;

[0036] The outer frame 6 is made of two pieces of elastic material bent into curved surfaces, and the guide planes of the two pieces fit each other to form a double-layer arch structure with an olive-shaped through hole; both ends of the olive-shaped through hole are flat surfaces;

[0037] The internal support frame 7 is supported in the concave surface of the elastic material, and includes a support plate which is parallel and smaller in area than the guide plane, and a support beam connected between the support plate and the concave surface; the side edge of the support plate in the width direction contacts the unstretched concave surface;

[0038] The middle electrode 8 includes an insulating plate and two first electrodes Cu-1; the insulating plate is located on the guide plane, and its side in the length direction is fixedly connected to the outer frame 6; the two first electrodes Cu-1 are respectively attached to the two surfaces of the insulating plate;

[0039] The friction layer 9 is arranged on the side of the support plate pointing to the middle electrode 8, and corresponds to the closest first electrode Cu-1 in space; the friction layer 9 includes a third electrode Cu-3 and a composite layer which are insulated from each other; the composite layer is stacked in sequence from the support plate to the middle electrode 8 with an adhesion layer, a second electrode Cu-2 and a rectangular friction material (FEP film); the adhesion layer stretches naturally when not subjected to pressure from the outer frame 6, so that the composite layer is closer to the corresponding first electrode Cu-1 relative to the third electrode Cu-3; a wire is provided between the third electrode Cu-3 and the second electrode Cu-2 to access the load.

[0040] Furthermore, the material of the internal support frame 7 is acrylic.

[0041] Furthermore, the first electrode Cu-1, the second electrode Cu-2 and the third electrode Cu-3 are made of copper.

[0042] Furthermore, the material of the outer frame 6 is polyethylene terephthalate.

[0043] Furthermore, the outer frame 6 seals the olive-shaped through hole after reserving the connection line of the load.

[0044] Furthermore, the length of the support plate is consistent with the height of the olive-shaped through hole.

[0045] Furthermore, the support beam and the support plate are vertically arranged; the support beam is fixedly connected to the concave surface; and the number of the support beams is not less than two.

[0046] like Figure 2 As shown in the figure, TENG is designed as a double-layer arch structure, which is mainly composed of an outer frame 1, an internal support frame 2, a middle electrode 3, and a friction layer 4. The arch curvature of the outer frame 1 is the natural curvature of the polyethylene glycolterephthalate (PET) material after heating, and the internal support frame 2 is made of acrylic material. Two rectangular copper electrodes 3 are attached to both sides of the middle support plate, and a rectangular friction material (fluorinated ethylene propylene, FEP) 4 is tightly attached to the outside of the middle copper electrode. The upper and lower layers of PET arch structures are combined to form a double-layer arch structure.

[0047] Among them, the design of the arch structure can solve the problem of collecting low-frequency wave energy. The generator for collecting wave energy in this application relies on the impact of the central ball, which then generates electrical energy through contact and separation movement. The design of the arch structure can effectively disperse the external pressure applied to it, increase its overall mechanical stability, reduce material wear and damage, and increase service life. The arch design allows the structure to deform appropriately when subjected to external force, thereby maintaining good friction contact and rebound conditions. It can also achieve a certain shock-absorbing effect, reducing energy loss caused by environmental vibration.

[0048] Embodiment 2:

[0049] As attached Figure 3 Based on the principle shown, the present application also provides a method for generating electricity by collecting low-frequency wave energy, using a friction nanogenerator for collecting low-frequency wave energy as described above; the method for generating electricity includes:

[0050] s1. When the outer frame 6 is not squeezed and deformed, the first electrode Cu-1 on the middle electrode 8 is separated from the rectangular friction material on the friction layer 9, and a negative charge remains on the surface of the rectangular friction material, while the first electrode Cu-1 and the second electrode Cu-2 carry a positive charge;

[0051] s2. When external force is applied to the outer frame 6, the elastic material of the outer frame 6 is deformed and squeezes the internal support frame 7 inward, so that the rectangular friction material on the internal support frame 7 contacts the first electrode Cu-1 on the corresponding side of the middle electrode 8; at the same time, the adhesion layer is also compressed so that the third electrode Cu-3 also contacts the first electrode Cu-1; in the friction layer 9, the rectangular friction material contacts and rubs with the second electrode Cu-2, so that the number of positive charges on the second electrode Cu-2 is greater than that on the first electrode Cu-1. Since the surface potential of the first electrode Cu-1 is lower than that of the second electrode Cu-2, the potential difference will induce the positive charge in the second electrode Cu-2 to be transferred to the first electrode Cu-1 through the external load and the third electrode Cu-3, so that the external load generates current;

[0052] Among them, the current flowing through the load only flows from the second electrode Cu-2 to the third electrode Cu-3, so that the output current of the friction nanogenerator has only one direction, and the current direction can be regulated without passing through the current sorting unit, which is conducive to simplifying the structure of the power management circuit in the prior art.

[0053] s3. When the external force is removed, the elasticity of the adhesive layer and the outer frame 6 will preferentially cause the first electrode Cu-1 to separate from the third electrode Cu-3, while the second electrode Cu-2 is still in contact with the rectangular friction material; this action will cut off the original circuit and prevent the positive charge from returning from the first electrode Cu-1 to the second electrode Cu-2;

[0054] s4. When the rebound of the outer frame 6 further causes the first electrode Cu-1 to separate from the rectangular friction material again and establish a potential difference, the positive charge will remain in the first electrode Cu-1; this rapid increase in voltage will cause electrostatic breakdown of the edge air between the first electrode Cu-1 and the second electrode Cu-2 to form an ionized air channel 10; allowing the positive charge to be transferred back to the second electrode Cu-2, thereby ultimately restoring the friction nanogenerator to the state of the first stage.

[0055] In the specific implementation, as shown in the attached Figure 3 As shown, the specific principle of the above power generation method is described as follows:

[0056] Phase I Figure 3 -i), the first electrode Cu-1 is separated from the FEP film, and a negative charge remains on the surface of the FEP film, while the first electrode Cu-1 and the second electrode Cu-2 have a positive charge.

[0057] In the second stage ( Figure 3-ii), when external force is applied to TENG, the first electrode Cu-1 contacts the FEP film, and the compressed adhesive film contacts the third electrode Cu-3. Since the surface potential of the first electrode Cu-1 is low, the negative charge on the FEP film will induce the positive charge in the second electrode Cu-2 to transfer to the first electrode Cu-1 through the external load and the third electrode Cu-3.

[0058] Among them, the lower surface potential of the first electrode Cu-1 is equivalent to that of the second electrode Cu-2. After the FEP film contacts and rubs with the second electrode Cu-2, the number of positive charges on the second electrode Cu-2 is greater than that on the first electrode Cu-1. When TENG is in the second stage, when TENG contacts, the positive charge on the second electrode Cu-2 will be transferred to the first electrode Cu-1 through the third electrode Cu-3.

[0059] Phase III Figure 3 -iii), when the pressure is removed, the elasticity of the adhesive film and the PET frame will first cause the first electrode Cu-1 to separate from the third electrode Cu-3, while the second electrode Cu-2 is still in contact with the FEP film; this action will cut off the original circuit and prevent the positive charge from returning from the first electrode Cu-1 to the second electrode Cu-2. Therefore, when the first electrode Cu-1 is separated from the FEP film again and the potential difference is established, the positive charge will remain in the first electrode Cu-1. This rapidly increasing voltage will cause electrostatic breakdown at the edges of the two electrodes, the first electrode Cu-1 and the second electrode Cu-2.

[0060] In the fourth stage ( Figure 3 -iv), the ionized air channel caused by the electrostatic breakdown between the first electrode Cu-1 and the second electrode Cu-2 allows the positive charges to be transferred back to Cu-2, thus finally restoring the TENG to the state described in the first stage.

[0061] Embodiment three:

[0062] As attached Figure 1 As shown, the present application also provides a self-generating buoy, including a waterproof and adaptive center of gravity shell 2, a luminous LED set and a supporting circuit; a plurality of friction nanogenerators 1 for collecting low-frequency wave energy as described above are arranged in the sealed space of the shell 2; the planar end of the friction nanogenerator 1 is arranged perpendicular to the horizontal plane, and the arched narrowed sides are connected end to end to form a power generation unit array 4, and the convex surface of the outer frame 6 points to the center of the polygon of the power generation unit array 4; a sphere 3 is arranged in the central area of ​​the polygon, and the mass of the sphere 3 is arranged to ensure that the rolling energy of the sphere squeezes the friction nanogenerator 1 in the impact direction, causing the outer frame 6 to deform and generate electricity; the luminous LED serves as a load for the friction nanogenerator 1.

[0063] Furthermore, the number of friction nanogenerators is set to six.

[0064] Specifically, Figure 1 As shown, the buoy mainly consists of three parts: the buoy shell 2, the TENG power generation unit array 4, and the sphere 3 rolling inside the buoy, forming a synchronous, stable and reliable ring structure, and the whole is encapsulated in a waterproof, center of gravity adaptive cylindrical shell 5. The overall wave energy collection device is a highly symmetrical cylindrical structure. The internal single TENG power generation unit 1 is a double-layer arch structure. The TENG array is at the bottom of the buoy, and the rolling sphere 3 is arranged in the middle of the TENG array, so that the sphere 3 can trigger the single TENG power generation unit to work with the movement of the waves. The buoy shell 2 is made of 3D printed PLA material for waterproof sealing.

[0065] As attached Figure 4 As shown, TENG can effectively collect wave energy from natural ocean wave environment. This application adopts the preferred structure of six friction nanogenerators 1 (TENG) connected end to end to form a power generation unit array 4, and the array is placed at the bottom of the buoy for testing. The test results show that the power generation unit array 4 has obvious omnidirectionality.

[0066] As attached Figure 5 As shown, the power generation unit array 4 constructed in the present application is tested at ultra-low vibration frequencies of 0.1Hz, 0.2Hz and 0.3Hz, and its current density and peak value gradually increase with the increase of frequency. The output shows the characteristics of positive pulse current DC, and no additional components are required for rectification, which greatly reduces the complexity of the system. At a low frequency of 0.1Hz, the current peak can still reach 23.5μA.

[0067] As attached Figure 6 As shown, the electric energy generated by the friction nanogenerator 1 can be directly stored in the capacitor element, wherein a 33 μF capacitor can be charged to 7.5 V. When the capacitor is charged to 7.5 V, it can be proved that the friction nanogenerator 1 of the present application can collect wave energy and store the collected energy.

[0068] As attached Figure 7 As shown, the output capacity of the power generation unit array 4 set in the buoy has also been verified in the actual marine environment. The picture shows that a mooring sea trial was successfully carried out in Sanya Bay, Sanya, China, and 50 high-brightness LEDs were successfully lit up.

[0069] In summary, the friction nanogenerator and power generation method for collecting low-frequency wave energy proposed in this application have the following advantages or beneficial effects:

[0070] 1. Simplified power management circuit: The design of TENG electrode arrangement enables it to directly supply power to commercial capacitors without additional power management circuit.

[0071] 2. Can respond to low-frequency excitation: The design of the TENG arch structure enables it to obtain voltage and current output in a low-frequency trigger test of 0.1 Hz.

[0072] 3. Can collect omnidirectional wave energy: by attaching Figure 4 The test diagram shows that the TENG constructed in this application is formed into a circular array for testing, which can respond to irregular wave motion and convert the mechanical energy of wave motion into electrical energy for output. According to the size ratio of the sphere 3 and the friction nanogenerator 1, other numbers (such as 4, 5, 8, etc., depending on the matching size of the sphere and the generator arch frame) of the friction nanogenerator 1 can also be arranged in a circular array to absorb the corresponding collision kinetic energy.

[0073] 4. Strong ability to adapt to the environment: Figure 7 It was demonstrated that placing a buoy equipped with TENG in a harsh actual marine environment can directly drive commercial LEDs to light up. It is expected to provide a continuous and stable energy supply for deep-sea equipment, thereby achieving efficient conversion and utilization of clean renewable energy.

[0074] 5. Simple manufacturing process: The TENG is made using a laser engraving machine for the outer shell and support frame, and the electrodes are pasted onto the acrylic substrate. The overall manufacturing process is simple and suitable for batch production.

[0075] Other Alternatives

[0076] 1. The negative friction material in the present invention is replaced by polytetrafluoroethylene, polydimethylsiloxane, polyimide film, aniline formaldehyde resin film, polyoxymethylene film, ethyl cellulose film, polyamide film, melamine formaldehyde film, polyethylene glycol succinate film, cellulose film, cellulose acetate film, polyethylene adipate film, polydiallyl phthalate film, regenerated fiber sponge film, polyurethane elastomer film, styrene propylene copolymer film, styrene butene copolymer film, artificial fiber film, polymethyl film, methacrylate film, polyethylene Polyvinyl chloride film, polyester film, polyisobutylene film, polyurethane flexible sponge film, polyethylene terephthalate film, polyvinyl butyral film, phenolic resin film, chloroprene rubber film, butadiene propylene copolymer film, natural rubber film, polyacrylonitrile film, poly(vinylidene chloride-co-acrylonitrile) film or polyethylene propylene carbonate film, polystyrene, polymethyl methacrylate, polycarbonate or liquid crystal polymer, polychloroprene, polyacrylonitrile, polybisphenol carbonate, polychloroether, polyvinylidene chloride, polyethylene, polypropylene, polyvinyl chloride and other polymers.

[0077] 2. There are many options for modifying the surface of the friction material, including but not limited to ion etching, physical vapor deposition (PVD) coating and other technologies. In addition, other modification technologies can also be used, such as surface plasma treatment, sputtering deposition, chemical vapor deposition, etc. These modification methods are intended to adjust the chemical composition, structure and properties of the surface of the friction material to enhance its triboelectric effect, wear resistance, conductivity and other properties, thereby enhancing the overall performance of the friction power generation module. In an embodiment, the selection of an applicable modification technology will depend on the requirements of the specific materials and applications to meet the different requirements for the performance of the friction power generation system. Therefore, this modification step is not limited to a specific technical means, but includes but is not limited to the above-mentioned ion etching, PVD coating and other methods.

[0078] 3. The electrode material can be selected from commonly used electrode materials, such as metals, alloys, conductive oxides or organic conductors, etc. The selection of specific electrode materials is not a factor limiting the scope of protection of the present invention. In practice, those skilled in the art can determine the selection of corresponding electrode layer materials and preparation methods based on the selection of each friction layer material to ensure good conductive contact between the electrode and the negative friction material. The selection of specific electrode layer materials is not a condition limiting the scope of protection of the present invention, and can be set by a method of fixing the material by pasting, or by preparing the electrode layer on the surface of the negative friction material.

[0079] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A friction nanogenerator for collecting low-frequency wave energy, characterized in that: From outside to inside, it includes an outer frame (6), an internal support frame (7), a middle electrode (8) and a friction layer (9); The outer frame (6) is composed of two pieces of elastic material bent into curved surfaces, and the guide planes of the two pieces are fitted to each other to form a double-layer arched structure with an olive-shaped through hole; both ends of the olive-shaped through hole are flat surfaces; The internal support frame (7) is supported in the concave surface of the elastic material, and comprises a support plate which is parallel to the guide plane and has an area smaller than that of the guide plane, and a support beam connected between the support plate and the concave surface; the side edge of the support plate in the width direction is in contact with the unstretched concave surface; The middle electrode (8) comprises an insulating plate and two first electrodes (Cu-1); the insulating plate is located on the guide plane, and its side in the length direction is fixedly connected to the outer frame (6); the two first electrodes (Cu-1) are respectively attached to two surfaces of the insulating plate; The friction layer (9) is arranged on a surface of the support plate pointing to the middle electrode (8), and corresponds in space to the closest first electrode (Cu-1); the friction layer (9) comprises a third electrode (Cu-3) and a composite layer which are insulated from each other; the composite layer comprises an adhesion layer, a second electrode (Cu-2) and a rectangular friction material which are stacked in sequence from the support plate to the middle electrode (8); the adhesion layer stretches naturally when not subjected to pressure from the outer frame (6), so that the composite layer is closer to the corresponding first electrode (Cu-1) relative to the third electrode (Cu-3); a wire is provided between the third electrode (Cu-3) and the second electrode (Cu-2) to access a load.

2. The friction nanogenerator for collecting low-frequency wave energy as claimed in claim 1, characterized in that: The material of the internal support frame (7) is acrylic.

3. The friction nanogenerator for collecting low-frequency wave energy as claimed in claim 2, characterized in that: The first electrode (Cu-1), the second electrode (Cu-2) and the third electrode (Cu-3) are made of copper.

4. The friction nanogenerator for collecting low-frequency wave energy as claimed in claim 3, characterized in that: The material of the outer frame (6) is polyethylene terephthalate.

5. The friction nanogenerator for collecting low-frequency wave energy as claimed in claim 4, characterized in that: The outer frame (6) seals the olive-shaped through hole after reserving the connection line of the load.

6. The friction nanogenerator for collecting low-frequency wave energy as claimed in claim 1, characterized in that: The length of the support plate is consistent with the height of the olive-shaped through hole.

7. The friction nanogenerator for collecting low-frequency wave energy as claimed in claim 6, characterized in that: The support beam is vertically arranged to the support plate; the support beam is fixedly connected to the concave surface; and the number of the support beams is not less than two.

8. A method for generating electricity by collecting low-frequency wave energy, characterized in that: A friction nanogenerator for collecting low-frequency wave energy as claimed in any one of claims 1 to 7 is used; the power generation method comprises: s1. When the outer frame (6) is not squeezed and deformed, the first electrode (Cu-1) on the middle electrode (8) is separated from the rectangular friction material on the friction layer (9), and a negative charge remains on the surface of the rectangular friction material, while the first electrode (Cu-1) and the second electrode (Cu-2) have a positive charge; s2. When an external force is applied to the outer frame (6), the elastic material of the outer frame (6) is deformed and squeezes the internal support frame (7) inward, so that the rectangular friction material on the internal support frame (7) contacts the first electrode (Cu-1) on the corresponding side of the middle electrode (8); at the same time, the adhesion layer is also compressed so that the third electrode (Cu-3) also contacts the first electrode (Cu-1); in the friction layer (9), the rectangular friction material contacts and rubs with the second electrode (Cu-2), so that the number of positive charges on the second electrode (Cu-2) is greater than that on the first electrode (Cu-1). Since the surface potential of the first electrode (Cu-1) is lower than that of the second electrode (Cu-2), the potential difference will induce the positive charge in the second electrode (Cu-2) to be transferred to the first electrode (Cu-1) through the external load and the third electrode (Cu-3); so that the external load generates current; s3. When the external force is removed, the elasticity of the adhesive layer and the outer frame (6) will preferentially cause the first electrode (Cu-1) to separate from the third electrode (Cu-3), while the second electrode (Cu-2) remains in contact with the rectangular friction material; this action will cut off the original circuit and prevent the positive charge from returning from the first electrode (Cu-1) to the second electrode (Cu-2); s4. When the rebound of the outer frame (6) further causes the first electrode (Cu-1) to separate from the rectangular friction material again and establish a potential difference, the positive charge will remain in the first electrode (Cu-1); this rapid increase in voltage will cause electrostatic breakdown of the edge air between the first electrode (Cu-1) and the second electrode (Cu-2) to form an ionized air channel (10); allowing the positive charge to be transferred back to the second electrode (Cu-2), thereby ultimately restoring the friction nanogenerator to the state of the first stage.

9. A self-generating buoy, comprising a waterproof and gravity-adaptive housing (2), a light-emitting LED set and a matching circuit; characterized in that: A plurality of friction nanogenerators (1) for collecting low-frequency wave energy as described in any one of claims 1 to 7 are arranged in the sealed space of the shell (2); the planar end of the friction nanogenerator (1) is arranged perpendicular to the horizontal plane, and the arched narrowed sides are connected end to end to form a power generation unit array (4), and the convex surface of the outer frame (6) points to the center of the polygon of the power generation unit array (4); a sphere is arranged in the central area of ​​the polygon, and the mass of the sphere is arranged to ensure that the rolling energy of the sphere squeezes the friction nanogenerator (1) in the impact direction, so that the outer frame (6) undergoes deformation and generates electricity; the light-emitting LED serves as the load of the friction nanogenerator (1).

10. The self-generating buoy according to claim 9, characterized in that: The number of the friction nanogenerators is set to 6.

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