A high-efficiency ball-shaped non-contact friction nanogenerator for collecting low-frequency wave energy

Abstract

The application discloses a ball-shaped non-contact friction nanogenerator for efficiently collecting low-frequency wave energy, and relates to the field of wave energy collection.The ball-shaped non-contact friction nanogenerator is composed of a stator and a rotor, and the stator and the rotor correspond to the outer shell and the inner shell of a concentric ball respectively.A copper electrode on the inner surface of the outer shell and a polytetrafluoroethylene (PTFE) film on the outer surface of the inner shell form a non-contact TENG, which converts mechanical energy into electrical energy.The widely-distributed, low-frequency and irregular-peak wave energy can be collected to supply power to small electronic devices.The provided non-contact TENG is low in cost, simple in structure and stable in performance, and provides a feasible scheme for collecting / using irregular wave energy, and has important practical significance.

Description

TECHNICAL FIELD

[0001] The application relates to the field of wave energy collection, in particular to a high-efficiency low-frequency wave energy collection ball-shaped non-contact friction nanogenerator with high durability. BACKGROUND

[0002] The massive consumption of fossil fuels brings heavy economic burden, severe energy crisis and long-term greenhouse effect, prompting people to find and utilize clean and environmentally friendly new energy. The global renewable energy is rich in variety, and a large amount of renewable blue energy is contained in the ocean which accounts for about 71% of the total area of the earth, including wave energy, tidal energy and the like. The wave energy has the advantages of green environmental protection, strong energy storage capacity, sustainability, wide distribution and strong predictability, and has great development significance.

[0003] In the current wave energy collection field, the traditional electromagnetic generator based on Faraday's law of electromagnetic induction is the mainstream wave energy collector. Since the output power of the traditional electromagnetic generator is proportional to the square of the frequency, a high and stable working frequency is required to obtain effective output. However, the wave energy belongs to high-entropy low-frequency energy, which greatly limits the application of conventional electromagnetic generators, and new wave energy collection technology needs to be developed urgently. In recent years, the friction nanogenerator (TENG) has developed rapidly, which is based on triboelectric and electrostatic induction effects. It has high applicability for low-frequency and low-amplitude energy collection and revolutionary significance in efficiently realizing large-scale wave energy collection. It is an important direction for future offshore power generation.

[0004] TENG has been widely used in various forms of environmental mechanical energy collection, such as mechanical vibration, walking, raindrops and the like. In the aspect of wave energy collection, TENGs with different structures such as ball-shaped, pendulum-shaped, buoy-shaped and seesaw-shaped have been proposed. Among them, the TENG based on the direct contact of the triboelectric electrode is the most widely used in the contact-separation working mode. However, continuous mechanical contact can cause wear and interface heating between the triboelectric electrodes, thereby reducing the durability of the TENG and causing the output performance to decay. SUMMARY

[0005] The application aims to solve the above problems, and provides a high-efficiency low-frequency wave energy collection ball-shaped non-contact friction nanogenerator. The ball-shaped structure is adopted, the outer spherical shell and the inner spherical shell are used as the stator and the rotor respectively, and the non-contact friction nanogenerator is formed, the durability and the energy conversion efficiency are improved, the wave energy can be converted into electric energy, and the small electronic equipment can be directly powered after rectification. The friction nanogenerator structure is simple, stable in performance, suitable for environments that need long-term stable operation and are difficult to maintain regularly, and has certain practical value.

[0006] In order to achieve the above purpose, the application adopts the following technical scheme:

[0007] A high-efficiency ball-type non-contact friction nanogenerator for collecting low-frequency wave energy, the assembly includes an outer spherical shell, an inner spherical shell, a swing assembly, a bearing, a shaft, and a counterweight, wherein the friction power generation unit capable of converting mechanical energy into electrical energy is non-contact.

[0008] The outer spherical shell is composed of two identical hollow hemispheres as a stator; the interface between the two hollow hemispheres is sealed and fixed to prevent water from entering the interior of the sphere;

[0009] The inner spherical shell is also composed of two identical hollow hemispheres as a rotor, which is arranged inside the outer spherical shell and can freely rotate in the outer spherical shell; the interface between the two hollow hemispheres is sealed and fixed to prevent water from entering the interior of the sphere;

[0010] The swing assembly is fixed to the bottom of the inner spherical shell to increase the swing effect of the inner spherical shell under the action of waves;

[0011] The counterweight is arranged on the swing assembly to lower the center of gravity of the entire device;

[0012] The bearing and the shaft are arranged between the outer spherical shell and the inner spherical shell to ensure that the inner spherical shell can rotate smoothly in the outer spherical shell;

[0013] The friction power generation unit includes two structures, two friction generators with the same structure and material on the upper and lower parts of the inner surface of the outer spherical shell and the outer surface of the inner spherical shell, each friction generator includes a first friction layer arranged on the outer surface of the inner spherical shell, and a interdigital electrode layer and a second friction layer arranged on the inner surface of the outer spherical shell, for converting mechanical energy into electrical energy.

[0014] Further, the bearing adopts super-lubricating ceramic bearing, and the shaft adopts steel shaft.

[0015] Further, the outer spherical shell is made of lightweight and corrosion-resistant materials, such as acrylic material; the outer spherical shell is cut into a complete circular hole at the connecting plane of the two hollow hemispheres, which is used to embed the super-lubricating ceramic bearing and the steel shaft, and two symmetric small holes are cut on both sides of the circular hole to facilitate the installation and removal of the concentric spherical shell and the lead-out of the wire.

[0016] Further, the inner spherical shell is made of lightweight and corrosion-resistant materials, such as acrylic material; the inner spherical shell is cut into a circular hole at the interface of the upper and lower hollow hemispheres, which corresponds to the circular hole of the outer spherical shell, and is used to embed the bearing and the steel shaft; the swing assembly is adhered to the arc surface at the bottom of the lower hollow hemisphere to fix the counterweight.

[0017] Further, the swing assembly can be formed by photosensitive resin 3D printing, and the whole is a spherical cap shape that can be completely attached to the arc surface of the bottom of the lower half hollow sphere. The arc surface of the spherical cap shape is completely adhered to the arc surface of the bottom of the lower half hollow sphere. The swing assembly is cut with a certain area of circular groove in the center of the plane, which is used to fix the cylindrical copper weight to reduce the gravity center of the device and facilitate the swing of the device.

[0018] Further, the first friction layer of the friction power generation unit is selected from a non-metallic insulating electret material with strong electronegativity. The second friction layer of the friction power generation unit is selected from a non-metallic insulating electret material with weak electronegativity. The interdigital electrode layer of the friction power generation unit is selected from a metal conductive film or a single-layer conductive material with weak electronegativity.

[0019] Further, the two friction generators of the friction power generation unit are connected in parallel through wires to obtain electric energy, and a rectifier circuit is used to supply power to the load.

[0020] Further, the interface between the two hollow hemispheres is sealed with hot melt adhesive or polytetrafluoroethylene sealing tape, and further fixed with waterproof tape.

[0021] The spherical non-contact friction nanogenerator for efficiently collecting low-frequency wave energy, taking the lower half spherical shell friction generator as an example, its working mode is divided into four steps:

[0022] 1) In the initial stage, the first friction layer electret material completely overlaps with the copper electrode I. Through pre-friction, the electric charge continuously accumulates on the electret material until saturation, and equal amounts of negative and positive charges are generated on the surfaces of the first and second friction layers, respectively. Meanwhile, two groups of interdigital copper electrodes I and II respectively induce equal and opposite charges;

[0023] 2) The rotor rotates counterclockwise relative to the stator, and the potential difference between the two groups of copper electrodes changes during rotation, generating a current that flows from copper electrode I to copper electrode II along the external circuit;

[0024] 3) The rotor continues to rotate, and the current continues to flow to copper electrode II until the electret material completely overlaps with copper electrode II, and the positive charge is completely transferred to copper electrode II;

[0025] 4) The rotor rotates further counterclockwise, and the other adjacent electret material of the first friction layer moves to the copper electrode I. At this time, the process is similar to step 2), but the difference is that the current direction changes from the copper electrode II to the copper electrode I until the electret material completely faces the copper electrode I. At this time, the positive charge is completely transferred to the copper electrode I. Thus, the friction nanogenerator completes one cycle and outputs alternating current. If the rotor rotates clockwise, the same principle applies. Under the periodic triggering of waves, the rotor rotates bidirectionally, which can continuously output alternating current. The output current can be rectified by a rectifier circuit, and then the energy storage element can be charged or directly power small electronic devices.

[0026] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0027] 1. Innovative non-contact design: The present application proposes a new type of spherical non-contact friction nanogenerator. The generator is composed of a stator and a rotor. The stator corresponds to the outer shell of a concentric sphere, while the rotor corresponds to the inner shell. This design allows the copper electrode on the inner surface of the outer shell to form a non-contact friction nanogenerator structure with the PTFE film on the outer surface of the inner shell. Through this non-contact structure, the present application can effectively convert mechanical energy into electrical energy. In particular, it can collect widely distributed, low-frequency, and irregular wave energy and convert it into electrical energy to power small electronic devices. The provided non-contact TENG has low cost, simple structure, and stable performance, providing a practical solution for collecting and utilizing irregular wave energy, which has important practical significance and broad application prospects.

[0028] 2. High energy output performance: Compared with traditional electromagnetic generators, the spherical non-contact friction nanogenerator described in the present application has higher output efficiency when collecting low-frequency sea wave fluctuations. According to the theory, the output current is proportional to the mechanical energy frequency, so the friction nanogenerator performs particularly well when facing high-entropy low-frequency wave energy. The output efficiency of the friction nanogenerator is much higher than that of traditional electromagnetic generators. This high energy output performance makes the present application have a significant advantage in collecting and utilizing wave energy, which can greatly increase the output performance and provide new possibilities for the development and utilization of wave energy.

[0029] 3. Large-scale integration and self-powered system: The present application can integrate multiple friction power generation units on a large scale according to specific environmental and actual needs, and collect blue wave energy in an array form. This integrated application not only improves the efficiency of energy collection, but also makes the entire system more stable and reliable. Through large-scale integration, the present application can form a self-powered system to convert continuous wave energy into electrical energy to power various small electronic devices. For example, it can light up LED lights and provide power support for small devices such as thermohygro meters, thereby achieving energy self-sufficiency.

[0030] 4. Low cost and long life: the non-contact friction nanogenerator made of copper electrode on the inner surface of the outer sphere and PTFE film on the outer surface of the inner sphere has low cost, simple structure, easy mass production and popularization and application. The non-contact design fundamentally avoids the physical contact of the friction material, thereby reducing the damage to the friction layer material and the energy loss caused by friction. This design not only prolongs the life of the device, but also reduces the performance decay, improves the energy conversion efficiency, and makes the whole system more stable and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a schematic diagram of the 3D structure of the present application.

[0032] Figure 2 is a schematic diagram of the cross-sectional structure of the present application.

[0033] Figure 3 is a schematic diagram of the structure and shape of the electrode layer and the friction layer material.

[0034] Figure 4 is a schematic diagram of the principle of the non-contact friction power generation unit.

[0035] Figure 5 is a test result diagram of the electrical output of the present application in a simulated wave environment.

[0036] Figure 6 is a durability test result diagram of the present application in a simulated wave environment.

[0037] Figure 7 is an effect diagram of the present application lighting a commercial LED. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and beneficial effects of the present application more clear, specific, and obvious, the present application will be further described in detail below in combination with the drawings and examples.

[0039] As shown in Figure 1 and 2 , the present embodiment is a spherical non-contact friction nanogenerator for efficiently collecting low-frequency wave energy, which comprises an outer sphere 1, an inner sphere 2, a swing assembly 3, an ultra-lubricating ceramic bearing 4, a stainless steel shaft 5, a counterweight copper block 6, and a friction power generation unit capable of converting mechanical energy into electrical energy, which is a non-contact friction nanogenerator.

[0040] In the present embodiment, the inner sphere 2 and the outer sphere 1 are both connected by two identical hollow hemispheres, which are divided into upper and lower hemispherical shells; the interface between the two hollow hemispheres is sealed with hot melt adhesive or polytetrafluoroethylene, and further fixed with waterproof tape to prevent water from entering the interior of the sphere.

[0041] The frictional power generation unit encapsulated in the outer spherical shell 1 includes two frictional power generators with the same structure and material on the upper and lower parts of the inner surface of the outer spherical shell 1 and the outer surface of the inner spherical shell 2, each of which includes a first frictional layer 7 on the outer surface of the inner spherical shell, and an interdigital electrode layer 8 and a second frictional layer 9 on the inner surface of the outer spherical shell.

[0042] The upper and lower hemispheres of the outer spherical shell 1 are made of acrylic material. Symmetrical semicircular holes are cut on the connecting plane of the two hollow hemispheres to form a complete circular hole, and the same drilling is performed on the back symmetric position to embed the super-lubricating ceramic bearing 4 and the stainless steel shaft 5.

[0043] The upper and lower hemispheres of the inner spherical shell 2 are made of acrylic material. A semicircular hole is cut on the connecting plane of the two hollow hemispheres to form a complete circular hole corresponding to the circular hole of the outer spherical shell 1, and the super-lubricating ceramic bearing 4 and the stainless steel shaft 5 are embedded, which can assemble the inner and outer spherical shells into coaxial spherical shells; the lower half hollow spherical bottom arc surface of the inner spherical shell 2 adheres a swing assembly to fix the counterweight block.

[0044] The swing assembly 3 is made of photosensitive resin 3D printing technology, and the whole is a spherical cap shape that can completely fit the lower half hollow spherical bottom arc surface of the inner spherical shell. In this embodiment, the swing assembly 3 is a spherical cap cut from a sphere. The spherical cap arc surface is completely adhered to the lower half hollow spherical bottom arc surface, and the swing assembly 3 is cut with a circular groove of a certain area in the center of the plane to fix the cylindrical counterweight copper block 6.

[0045] The first frictional layer 7 of the frictional power generation unit is selected from a non-metallic insulating electret material with strong electronegativity. Specifically, polytetrafluoroethylene (PTFE) is used in this embodiment, with a thickness of 50 μm. The PTFE substrate is cut into a leaf-shaped PTFE strip with an arc edge as shown in the figure, with a short side of 5 mm and a long side of 300 mm, and arranged at equal intervals on the outer surface of the inner spherical shell with an interval of 7 mm. Figure 3

[0046] The second frictional layer of the frictional power generation unit is selected from a non-metallic insulating electret material with weak electronegativity. Specifically, nylon is used in this embodiment, with a thickness of 50 μm, and is pasted as the outermost layer on the inner surface of the outer spherical shell, covering the interdigital electrode of the frictional power generation unit.

[0047] ​The interdigital electrode layer of the friction power generation unit is selected from a metal conductive thin film or a single layer conductive material with weak electronegativity. Specifically, in the embodiment, a flexible interdigital copper foil electrode manufactured by a commercial PCB technology is adopted, with a thickness of 35 μm and a 25 μm thick polyimide (PI) back adhesive 10 for convenient sticking to the inner surface of the outer spherical shell. The copper foil electrode is similar to the PTFE strip, in the shape of a blade with arc edges, with a short edge of 5 mm and a long edge of 300 mm, and is arranged on the inner surface of the outer spherical shell at a spacing of 1 mm. The copper foil electrode is divided into two groups (such as copper electrode I 81 and copper electrode II 82 in Figure 2 the embodiment), and each group of copper foil electrodes is connected in parallel to form an interdigital electrode. A nylon film covers the interdigital electrode layer to prevent breakdown discharge and increase output.

[0048] The friction power generation unit includes two friction power generators in the upper and lower halves of the hollow spherical shell, which are connected in parallel by wires to obtain electrical energy and supply power to the load by using a rectifier circuit.

[0049] The working mode of the lower half of the spherical shell friction power generator is divided into four steps.

[0050] 1) Initial stage: The electret material (PTFE film in the embodiment, as the first friction layer) completely overlaps the copper electrode I (part of the interdigital electrode), and the charge on the electret material continuously accumulates until it reaches a saturated state through pre-friction or electron injection. At this time, the first friction layer (PTFE film) has an equal amount of negative charge on its surface, while the second friction layer (nylon film) has an equal amount of positive charge on its surface. At the same time, due to the electrostatic induction effect, the two groups of interdigital electrodes (copper electrode I and copper electrode II) respectively induce equal but opposite polarity charges.

[0051] 2) Counterclockwise rotation stage: When the rotor rotates counterclockwise relative to the stator, the potential difference between the two groups of interdigital electrodes (copper electrode I and copper electrode II) changes during rotation. Due to the uneven distribution of charges on the electret material, a potential difference is generated during rotation, thereby driving electrons to flow in the external circuit. Specifically, the current flows out of the copper electrode I with negative charge (which is in contact with the electret material at this time), flows along the external circuit to the copper electrode II with positive charge induction.

[0052] 3) Complete overlap stage: As the rotor continues to rotate, the current continues to flow to the copper electrode II until the electret material completely overlaps the copper electrode II. At this time, the positive charge on the electret material is completely transferred to the copper electrode II, and the copper electrode I returns to a neutral state due to the loss of negative charge.

[0053] 4) Another piece of electret material moves to electrode I stage: the rotor further rotates counterclockwise, at this time, another piece of electret material moves to copper electrode I, at this time, similar to step 2), the difference is that the current direction changes from copper electrode II to copper electrode I, due to the change of the charge distribution on the electret material again, the positive charge on the copper electrode II begins to decrease, and the copper electrode I begins to induce negative charge. Therefore, the current direction changes from copper electrode II to copper electrode I, this process continues until another piece of electret material completely faces copper electrode I. At this time, TENG completes a complete cycle, outputting alternating current, the detailed process is shown in Figure 4

[0054] It should be pointed out that if the rotor rotates clockwise, the above process is also applicable, but the current direction will be reversed. That is, the current flows from copper electrode II to copper electrode I (in the initial stage), and then flows reversely with the rotation of the rotor.

[0055] Under the periodic triggering of waves, the rotor rotates bidirectionally, thereby continuously outputting alternating current. In order to utilize these alternating currents to charge energy storage elements or directly power small electronic devices, a rectifier circuit needs to be used to rectify the output current. The rectifier circuit can convert alternating current into direct current, thereby meeting the power supply needs of various electronic devices.

[0056] In this embodiment, the first friction layer and the second friction layer are PTFE film and nylon film respectively, and the two materials have good electronegativity difference and wear resistance. The two groups of interdigital electrodes (copper electrode I and copper electrode II) respectively include 25 copper electrodes. These copper electrodes are arranged on the inner surface of the outer spherical shell through a precise manufacturing process, and form effective friction power generation units with the electret material.

[0057] In order to verify the effectiveness of the present application, the following embodiment is applied to illustrate:

[0058] I. Wave simulation system and electrical performance test

[0059] A wave simulation system is successfully built by using a water tank and a wave making pump group to simulate a real low frequency water wave vibration environment. Under this simulated wave condition, the electrical performance test of the present application is carried out.

[0060] From the electrical performance test data shown in Figure 5 It can be seen that the spherical non-contact TENG in this embodiment exhibits excellent performance in the simulated wave system. The open circuit voltage of TENG in the simulated wave system is as high as 130.6 V with low frequency water wave vibration, and the short circuit current is 16.3 μA. These data fully prove that the present application can effectively generate electric energy under the condition of low frequency water wave vibration.

[0061] In Figure 5 ​In the above experimental environment, the durability test of the application is carried out for 5 hours. As shown in the durability test data, the current output of the application does not show any signs of attenuation in 5 hours of continuous work. This result not only verifies the excellent durability of the application, but also shows that the application can provide stable power for a long time in practical application.

[0062] II. Durability test

[0063] In the above experimental environment, the durability test of the application is carried out for 5 hours. As shown in the durability test data, the current output of the application does not show any signs of attenuation in 5 hours of continuous work. This result not only verifies the excellent durability of the application, but also shows that the application can provide stable power for a long time in practical application. Figure 6

[0064] III. Commercial LED lighting experiment

[0065] In order to further verify the ability of the application to power small electronic devices, a commercial LED lighting experiment is carried out. As shown in the effect diagram of TENG lighting commercial LED, in the simulation system, the ball-shaped non-contact TENG described in this embodiment can light more than 40 LEDs with the triggering of waves in the simulation system. And after a long time of work test for a month, the application can still stably power these LEDs. This result proves the ability of the application to power small electronic devices, as well as its excellent durability, and the application has wide potential in practical application. Figure 7

[0066] The application adopts a spherical structure, the inner spherical shell is a rotor, and rotates bidirectionally under the periodic triggering of water waves, converting mechanical energy into electrical energy. The inner and outer spherical shells constitute a non-contact TENG through the air gap between the inner and outer spherical shells and the super-lubricating ceramic bearing, so that the application has the advantages of simple structure design, easy preparation, high energy conversion rate, stable performance, long device life, easy large-scale manufacturing, array integration application, etc. Through experimental verification, the application can effectively convert the widely distributed, low-frequency high-entropy, peak irregular wave energy into electrical energy, which can be directly used to power small electronic devices after rectification, such as lighting LED, charging capacitor, etc.

[0067] The structure and shape of the application are not limited to the embodiment described above. In complex environments, the device can be modified to a multi-layer spherical structure based on this embodiment to obtain more friction power generation units and larger electrode area, thereby improving space utilization and obtaining higher output performance. The number of devices can also be increased to form a power generation array to effectively improve the output current.

[0068] ​​The application provides a ball-shaped non-contact TENG for efficiently collecting low-frequency wave energy. The non-contact TENG is formed through the air gap between the stator and the rotor, fundamentally effectively avoids the physical contact of the friction material, reduces the damage to the friction layer material, reduces the energy loss caused by friction, improves the energy conversion rate, improves the durability of the material, prolongs the service life of the device, and the output performance can be controlled by adjusting the device structure parameters such as the air gap distance, the inner and outer spherical shell diameters, and the like. The wave energy can be efficiently collected, and alternating current can be output. The alternating current is converted into direct current by the rectifier, and then small electronic equipment can be directly powered. In the efficient realization of large-scale wave energy collection, it has broad application prospects.

[0069] The above examples are only preferred embodiments of the application and cannot be considered as limiting the scope of the application. Any equivalent changes and improvements made within the scope of the application should still belong to the patent scope of the application.

Claims

1. A spherical non-contact frictional nanogenerator for efficient harvesting of low-frequency wave energy, characterized in that The device comprises an outer spherical shell, an inner spherical shell, a swing assembly, a bearing, a shaft, a counterweight, and a friction power generation unit, wherein the friction power generation unit for converting mechanical energy into electrical energy is non-contact type. The outer spherical shell is composed of two identical hollow hemispheres as stators, and the interface between the two hollow hemispheres is sealed and fixed to prevent water from entering the interior of the spherical shell. The inner spherical shell is also composed of two identical hollow hemispheres as rotors, which are arranged inside the outer spherical shell and can freely rotate in the outer spherical shell, and the interface between the two hollow hemispheres is sealed and fixed to prevent water from entering the interior of the spherical shell. The swing assembly is fixed to the bottom of the inner spherical shell and is used to increase the swing effect of the inner spherical shell under the action of waves. The counterweight is arranged on the swing assembly and is used to lower the center of gravity of the entire device. The bearing and the shaft are arranged between the outer spherical shell and the inner spherical shell to ensure that the inner spherical shell can smoothly rotate in the outer spherical shell. The friction power generation unit comprises two friction power generators with the same structure and material on the upper and lower parts of the inner surface of the outer spherical shell and the outer surface of the inner spherical shell, each of which comprises a first friction layer arranged on the outer surface of the inner spherical shell, and a second friction layer and an interdigital electrode layer arranged on the inner surface of the outer spherical shell, and is used to convert mechanical energy into electrical energy. The bearing is an ultra-lubricating ceramic bearing, and the shaft is a steel shaft.

2. The spherical non-contact frictional nanogenerator for efficiently harvesting low-frequency wave energy according to claim 1, characterized in that The outer spherical shell is made of acrylic material, and symmetric semicircular holes are cut at the connecting plane of the two hollow hemispheres to form a complete circular hole for embedding the ultra-lubricating ceramic bearing and the steel shaft. Two symmetric small holes are cut on both sides of the circular hole to facilitate the installation and removal of the concentric spherical shell and the leading of wires.

3. The spherical non-contact frictional nanogenerator for efficiently harvesting low-frequency wave energy according to claim 1, wherein The inner spherical shell is made of acrylic material, and a circular hole is cut at the interface between the upper and lower hollow hemispheres to correspond with the circular hole of the outer spherical shell for embedding the bearing and the steel shaft. The bottom arc surface of the lower hollow hemisphere is adhered with the swing assembly for fixing the counterweight.

4. The spherical non-contact frictional nanogenerator for efficiently harvesting low-frequency wave energy according to claim 1, wherein The swing assembly is made by 3D printing of photosensitive resin and has a spherical cap shape that can completely fit the bottom arc surface of the lower hollow hemisphere of the inner spherical shell. The arc surface of the spherical cap shape is completely adhered to the bottom arc surface of the lower hollow hemisphere, and a circular groove with a certain area is cut at the center of the swing assembly plane for fixing the cylindrical copper counterweight to lower the center of gravity of the device and facilitate the swing of the device.

5. The spherical non-contact frictional nanogenerator for efficiently harvesting low-frequency wave energy according to claim 1, wherein The first friction layer of the friction power generation unit is selected from a non-metallic insulating electret material with strong electronegativity, the second friction layer is selected from a non-metallic insulating electret material with weak electronegativity, and the interdigital electrode layer is selected from a metallic conductive film or a single-layer conductive material with weak electronegativity.

6. The spherical non-contact frictional nanogenerator for efficiently harvesting low-frequency wave energy according to claim 1, wherein The two friction power generators of the friction power generation unit are connected in parallel through wires to obtain electrical energy, and a rectifier circuit is used to supply power to the load.

7. The spherical non-contact frictional nanogenerator for efficiently harvesting low-frequency wave energy according to claim 1, wherein The interface between the two hollow hemispheres is sealed with hot melt adhesive or polytetrafluoroethylene sealing tape and further fixed with waterproof tape.

8. The spherical non-contact frictional nanogenerator for efficiently harvesting low-frequency wave energy according to claim 1, wherein The working mode is as follows:

9. The spherical non-contact frictional nanogenerator for efficiently harvesting low-frequency wave energy according to claim 1, wherein 1) In the initial stage, the first friction layer electret material completely overlaps with the copper electrode I. Through pre-friction, the electric charge continuously accumulates on the electret material until saturation, and equal amounts of negative and positive charges are generated on the surfaces of the first and second friction layers, respectively. Meanwhile, two groups of interdigital copper electrodes I and II respectively induce equal and opposite charges. ​ 2) The rotor rotates counterclockwise relative to the stator, the potential difference between the two groups of copper electrodes changes during the rotation, and the current generated flows from copper electrode I to copper electrode II along the external circuit; 3) The rotor continues to rotate, and the current continues to flow to copper electrode II until the electret material completely overlaps with copper electrode II, and the positive charge is completely transferred to copper electrode II; 4) The rotor further rotates counterclockwise, and the other adjacent electret material of the first friction layer moves to copper electrode I. At this time, the process is similar to step 2), but the current direction changes from copper electrode II to copper electrode I until the electret material completely faces copper electrode I, at which time the positive charge is completely transferred to copper electrode I. At this point, the friction nanogenerator completes one cycle and outputs alternating current. If the rotor rotates clockwise, the same applies. Under the periodic triggering of waves, the rotor rotates in both directions, continuously outputting alternating current. The output current is rectified using a rectifier circuit, which can then charge energy storage elements or directly power small electronic devices.

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