Deep sea nano-generator, preparation method thereof and water flow energy collecting device

Abstract

The invention discloses a deep sea nano-generator, a preparation method thereof and a water flow energy collecting device. The nano-generator is of a symmetrical structure and comprises a packaging film layer, an electrode layer, a positive friction film layer, an oil layer, a negative friction film layer, an electrode layer and a packaging film layer which are sequentially stacked from top to bottom, and the electrode layer is connected with a wire; the negative friction film layer is a polyvinylidene fluoride film doped with titanium dioxide. According to the invention, the PVDF film doped with titanium dioxide is used as the negative friction layer, so that the mechanical property of the nano-generator is improved, and the nano-generator adapts to a high-pressure working environment of a deep sea; a single oil layer air layer is adopted, and the oil content of the oil layer is reduced, so that the performance output of the nano generator under the deep sea pressure is improved. The water flow energy collecting device can still supply power stably in a deep sea environment with high pressure under the condition that the water flow speed is low; and the device can still work normally under the hydrostatic pressure of 20Mpa.

Description

Technical Field

[0001] The present invention belongs to the technical field of generators, and in particular relates to a deep-sea nanogenerator and a preparation method thereof, and a water flow energy collection device. Background Art

[0002] The Marine Internet of Things (MIoT) is an increasingly important foundation for marine development and protection. It consists of various underwater marine distributed sensors. However, its energy supply problem has always troubled researchers. The traditional battery power supply method is not only costly, but also needs to be replaced regularly. For sensors in deep-sea environments, frequent power supply replacement means high maintenance costs. At the same time, submarine sensors used for military target monitoring are not suitable for regular maintenance. Frequent battery replacement is likely to increase exposure risks. Therefore, it is urgent to develop a self-powered technology suitable for submarine sensors, which can greatly reduce the maintenance cost of submarine sensors, increase the service life of sensors, and expand the application field of submarine sensors. Therefore, it is particularly important to find an efficient, stable and economical self-powered technology. Friction nanogenerators have attracted much attention due to their low material price, simple device structure, and high energy collection efficiency.

[0003] In recent years, some studies have proposed flexible seaweed-like triboelectric nanogenerators (S-TENGs) that can harvest wave energy underwater (see reference: M.Xu, et al., ACS Nano, 15, 10 (2021)), which can be used in a wide range of marine scenarios. The seaweed-like structure of S-TENG can swing under the action of water flow to convert kinetic energy into electrical energy. Among them, multiple S-TENGs connected in parallel have been shown to power LEDs and thermometers in marine environments. Since most marine Internet of Things (MIoT) sensors operate using micropower, the inherently stable and cost-effective S-TENG can be an effective way to achieve battery independence for most marine Internet of Things. However, below 100m from the ocean surface, the reduction in water flow velocity and the change in water flow direction make it difficult to collect wave energy, making it very inconvenient for the current underwater triboelectric nanogenerators to collect this energy. Moreover, on the seabed, especially in the deep sea, the hydrostatic pressure will increase by 1MPa for every 100m increase in ocean depth. The influence of pressure will cause the air layer in the friction nanogenerator to be squeezed, making it difficult for the friction layers to contact and separate. At the same time, some electronic components connected to the nanogenerator will also be squeezed, causing the friction nanogenerator to fail to work properly on the seabed.

[0004] Therefore, there is an urgent need to provide a new friction nanogenerator that can adapt to the high pressure and low flow rate conditions of the deep sea environment, work effectively under these conditions and power micro-electrical appliances. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a deep-sea nanogenerator and a preparation method thereof, and a water flow energy collection device. The nanogenerator described in the present invention can adapt to the deep-sea environment, and can still provide stable power supply in a deep-sea environment with high pressure and complex flow rate, which is beneficial to the power supply maintenance of deep-sea equipment (such as sensors).

[0006] The inventive concept of the present invention is as follows: the present invention uses a polyvinylidene fluoride (PVDF) film doped with titanium dioxide as a negative friction layer, and utilizes the high tensile strength of PVDF (more than 50MPa at room temperature). When doped with titanium dioxide, the roughness is increased while the mechanical properties are slightly reduced. Compared with the traditional bacterial cellulose doped film, the titanium dioxide doped PVDF film has higher mechanical properties and is more suitable for the high-pressure working environment of the deep sea. At the same time, the present invention uses a single oil layer to be added between the film layer and the electrode layer to replace the air layer, and reduces the oil content of the oil layer to reduce the adverse effect of the oil layer on the output performance of the nanogenerator, thereby improving the performance output of the nanogenerator under deep-sea pressure.

[0007] When the nanogenerator of the present invention is used, it is installed at the tail of the guide plate, and a triangular bluff body is arranged on the truncated cone base. The critical flow rate range of the nanogenerator is expanded by increasing the vortex formed by the water flowing through the triangular bluff body. The device is selected according to the direction of the flow rate by assembling the truncated cone base, the triangular bluff body and the guide plate, so that the nanogenerator can still generate electricity stably when the water flow direction is not fixed and the flow rate environment is unstable. In addition, the triangular bluff body, the guide plate and the truncated cone base of the present invention are all made of polytetrafluoroethylene by milling, and the structure is simple. There is no assembly interface problem of different materials between the various parts, and there is no mismatch problem under high hydrostatic pressure.

[0008] Therefore, the present invention obtains a nano-engine with high output performance through the selection and preparation of specific materials, and optimizes the structural design to collect underwater low water flow energy, thereby obtaining a high-performance water flow energy collection device, which can still provide stable power supply in a deep-sea environment with a high pressure of 20Mpa and a complex flow rate environment.

[0009] In order to solve the above technical problems, the first aspect of the present invention provides a nanogenerator, which has a symmetrical structure and includes, from top to bottom, an encapsulation film layer, an electrode layer, a positive friction film layer, an oil layer, a negative friction film layer, an electrode layer and an encapsulation film layer stacked in sequence, wherein the electrode layer is connected to a wire; and the negative friction film layer is a polyvinylidene fluoride film doped with titanium dioxide.

[0010] Preferably, in the negative friction film layer, the mass ratio of titanium dioxide to polyvinylidene fluoride is (1-7):(93-99); for example, the mass ratio of titanium dioxide to polyvinylidene fluoride is 1:99, 4:96, 5:95, 7:93.

[0011] Preferably, the positive friction film layer is selected from bacterial nanocellulose film.

[0012] Preferably, the encapsulation film layer is selected from polytetrafluoroethylene film.

[0013] Preferably, the electrode layer is aluminum foil, silver foil or copper foil.

[0014] Preferably, the components of the oil layer include at least one of perfluoropolyether, squalane and paraffin oil.

[0015] Preferably, the dimensions of the positive friction film layer and the negative friction film layer are equal, which is length×width=(10-12)cm×(5-10)cm; for example, the dimensions of the positive friction film layer and the negative friction film layer are length×width=8cm×4cm and length×width=10cm×5cm.

[0016] Preferably, the sizes of the electrode layer, the oil layer, the positive friction film layer and the negative friction film layer are consistent.

[0017] Preferably, the size of the encapsulation film layer is slightly larger than that of the electrode layer, with a length and width of (12-16) cm×(6-10) cm.

[0018] A second aspect of the present invention provides a method for preparing a nanogenerator, comprising the following steps:

[0019] (1) Two electrodes are taken and pasted on the surfaces of two packaging films respectively, with the surfaces of the two electrodes facing each other, to form two electrode layers and two packaging film layers;

[0020] (2) coating the surfaces of the two electrode layers in step (1) with a titanium dioxide-doped polyvinylidene fluoride solution and a bacterial nanocellulose solution, respectively, to form a negative friction film layer and a positive friction film layer; and then adding perfluoropolyether, squalane or paraffin oil between the negative friction film layer and the positive friction film layer to form an oil layer;

[0021] (3) Two electrode layers are connected respectively with two wires and packaged to obtain the nanogenerator.

[0022] Preferably, in step (2), the amount of perfluoropolyether, squalane or paraffin oil added is 10-100 μL; further preferably, the amount of perfluoropolyether, squalane or paraffin oil added is 20-50 μL.

[0023] Preferably, in step (3), the packaging material is waterproof glue.

[0024] Preferably, the waterproof adhesive is silicone or PTFE tape.

[0025] The third aspect of the present invention provides a water flow energy collection device, comprising the above-mentioned nanogenerator, a guide plate, a triangular bluff body and a truncated cone base; the nanogenerator is arranged at the tail of the guide plate, and the triangular bluff body is installed on the truncated cone base; the guide plate is connected to the triangular bluff body, and can drive the triangular bluff body to rotate on the truncated cone base under the action of water flow.

[0026] Preferably, there are a plurality of the nanogenerators, and the plurality of the nanogenerators are connected in parallel.

[0027] Preferably, the number of the nanogenerators is 6-12.

[0028] Preferably, the water flow energy collection device also includes a sensor and an LED lamp.

[0029] Preferably, the guide plate, triangular bluff body and truncated cone base are all made of polytetrafluoroethylene, which avoids the interface problem between different materials and does not cause mismatch due to different Poisson's ratios between different materials under high hydrostatic pressure. At the same time, the use of non-metallic connectors can effectively avoid structural failure caused by metal corrosion in deep-sea high-pressure environments.

[0030] Compared with the prior art, the above technical solution of the present invention has at least the following technical effects or advantages:

[0031] (1) The present invention uses a PVDF film doped with titanium dioxide as a negative friction layer, and utilizes the high tensile strength of PVDF at room temperature. When doped with titanium dioxide, the roughness is increased while the mechanical properties are slightly reduced, thereby improving the mechanical properties of the nanogenerator to adapt to the high-pressure working environment of the deep sea. At the same time, a single oil layer is used to replace the air layer, and the oil content of the oil layer is reduced, thereby reducing the adverse effect of the oil layer on the output performance of the nanogenerator, thereby improving the performance output of the nanogenerator under deep-sea pressure.

[0032] (2) When the nanogenerator of the present invention is used, it is installed at the tail of the guide plate, and a triangular bluff body is arranged on the truncated cone base. The critical flow velocity range of the nanogenerator is expanded by increasing the vortex formed by the water flowing through the triangular bluff body. The device is assembled according to the direction of the flow velocity through the truncated cone base, the triangular bluff body and the guide plate, so that the nanogenerator can still generate electricity stably when the water flow direction is not fixed and the flow velocity environment is unstable. At the same time, the structure can adjust its own shape according to the flow velocity direction and turn to the direction with the maximum flow velocity by itself, so as to effectively collect ocean current energy.

[0033] (3) The present invention is based on the self-powered technology of ocean energy friction nanogenerators. Through the design and optimization of materials, mechanical structures, circuits, etc., it provides clean energy for seabed sensors, expands the application field of friction nanogenerators, and provides cutting-edge and leading technical support for the development of a new generation of self-powered seabed sensors. Through the design and optimization of device materials, mechanical structures, etc., a friction nanogenerator that can collect low-frequency ocean energy, store, and sense and is suitable for the seabed environment is developed, which can still provide stable power supply in a deep-sea environment with a high pressure of 20Mpa and a complex flow rate environment, which is equivalent to having the potential to generate electricity 2,000 meters underwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of a nanogenerator according to Embodiment 1 of the present invention;

[0035] Figure 2 Schematic diagram of the structure of a water flow energy collection device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention is described in detail below in conjunction with the examples, so that the technical personnel of the relevant technical field can understand the present invention. It is necessary to point out here that the examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. The non-essential improvements and adjustments made to the present invention by the skilled person in the relevant field according to the above invention content should still belong to the scope of protection of the present invention. At the same time, the raw materials mentioned below that are not described in detail are all commercially available products; the process steps or preparation methods that are not mentioned in detail are all process steps or preparation methods known to those skilled in the art.

[0037] The schematic diagram of the structure of the nanogenerator prepared in each embodiment of the present invention is as follows Figure 1 As shown, Figure 1 110 represents the encapsulation film layer, 120 represents the electrode layer, 130 represents the positive friction film layer, 140 represents the oil layer, 150 represents the negative friction film layer, and 160 represents the wire. Figure 1 It can be seen that the nanogenerator has a symmetrical structure, with the oil layer 140 as the axis of symmetry, and includes, from top to bottom, an encapsulation film layer 110, an electrode layer 120, a positive friction film layer 130, an oil layer 140, a negative friction film layer 150, an electrode layer 120 and an encapsulation film layer 110 stacked in sequence, and the two electrode layers 120 are connected to two wires 160 respectively.

[0038] The structural schematic diagram of the water flow energy collection device prepared in each embodiment of the present invention is as follows Figure 2 As shown, Figure 2 210 represents a truncated cone base, 220 represents a triangular blunt body, 230 represents a guide plate, and 240 represents a nanogenerator. Figure 2 It can be seen that the water flow energy collection device includes a nanogenerator 240, a guide plate 230, a triangular bluff body 220 and a truncated cone base 210. The nanogenerator 240 is installed at the tail of the guide plate 230, and the triangular bluff body 220 is installed on the truncated cone base 210. Under the action of the water flow, the guide plate 230 can promote the rotation of the triangular bluff body 220 and the truncated cone base 210 underwater.

[0039] When the water flow energy collection device is working, the guide plate 230 is used to collect the water flow and drive the triangular bluff body 220 to rotate on the truncated cone base 210; after rotating to the direction of maximum flow velocity, the triangular bluff body 220 will cut the water flow to form disturbance, driving the nanogenerator 240 fixed at the tail of the guide plate 230 to vibrate, thereby achieving stable power generation at low water flow velocity.

[0040] As a preferred embodiment, the guide plate 230, the triangular bluff body 220 and the truncated cone base 210 are all made of polytetrafluoroethylene, which will not cause mismatch due to different Poisson's ratios between different materials under high hydrostatic pressure, and can effectively avoid structural failure caused by metal corrosion in deep-sea high-pressure environments.

[0041] Example 1

[0042] A method for preparing a nanogenerator comprises the following steps:

[0043] (1) Take two electrodes (length × width = 8 cm × 4 cm) and paste them on the surfaces of two packaging films (length × width = 10 cm × 5 cm) respectively, with the surfaces of the two electrodes facing each other, to form two electrode layers and two film layers;

[0044] (2) dissolving polyvinylidene fluoride with a molecular weight of 600,000 in dimethylformamide (DMF) to obtain a polyvinylidene fluoride solution with a concentration of 13 wt%, adding titanium dioxide (the mass ratio of titanium dioxide to polyvinylidene fluoride is 4:96), and ultrasonically dispersing to obtain a polyvinylidene fluoride solution doped with titanium dioxide; then coating the solution on the surface of an electrode prepared in step (1), and drying the solution by scraping to form a negative friction film layer;

[0045] (3) dissolving bacterial nanocellulose in water to obtain a bacterial nanocellulose solution with a concentration of 10 wt%, and then coating the solution on the surface of another electrode prepared in step (1), and vacuum drying the solution to form a positive friction film layer;

[0046] (4) Add 20 μL of perfluoropolyether between the negative friction film layer obtained in step (2) and the positive friction film layer obtained in step (3) to form an oil layer; then use two copper wires to connect the two electrode layers respectively to play a lead-out role; then use PTFE tape with a length × width = 18 cm × 12 cm to encapsulate and fix, and use silicone (Dow Corning 734) to waterproof the part where the copper wire is led out to obtain a nanogenerator.

[0047] A method for preparing a water flow energy collection device comprises the following steps:

[0048] (1) rectifying the nanogenerator prepared in this embodiment using a rectifier (DB207);

[0049] (2) Place the truncated cone base, triangular blunt body, guide plate and the six parallel-connected nanogenerators rectified as above, Figure 2 The structure shown in the figure is assembled; and the nanogenerator is connected with the LED light and the underwater electronic sensor. The electronic sensor and the LED light are encapsulated with epoxy resin in the reserved space of the triangular blunt body to obtain a water flow energy collection device.

[0050] Example 2

[0051] The difference between Example 2 and Example 1 is that, when preparing the nanogenerator of Example 2, the mass ratio of titanium dioxide to polyvinylidene fluoride is 1:99, and the other preparation processes are the same as those of Example 1.

[0052] Example 3

[0053] The only difference between Example 3 and Example 1 is that, when preparing the nanogenerator of Example 3, the mass ratio of titanium dioxide to polyvinylidene fluoride is 5:95, and the other preparation processes are the same as those of Example 1.

[0054] Example 4

[0055] The only difference between Example 4 and Example 1 is that, during the preparation of the nanogenerator of Example 4, the mass ratio of titanium dioxide to polyvinylidene fluoride is 7:93, and the other preparation processes are the same as those of Example 1.

[0056] Comparative Example 1

[0057] The only difference between Comparative Example 1 and Example 1 is that, during the preparation of the nanogenerator in Comparative Example 1, the negative friction film layer does not contain titanium dioxide, that is, a polyvinylidene fluoride solution not doped with titanium dioxide is coated, and the other preparation processes are the same as those in Example 1.

[0058] Comparative Example 2

[0059] The only difference between Comparative Example 2 and Example 1 is that, during the preparation of the nanogenerator in Comparative Example 2, an equal amount of barium titanate is used to replace titanium dioxide in the negative friction film layer, that is, a polyvinylidene fluoride solution doped with barium titanate is coated, and the other preparation processes are the same as those in Example 1.

[0060] Comparative Example 3

[0061] The only difference between Comparative Example 3 and Example 1 is that the water flow energy collection device of Comparative Example 3 does not include the triangular blunt body and the frustum base during assembly, that is, the guide plate is only connected to the nanogenerator.

[0062] Comparative Example 4

[0063] The nanogenerator is prepared according to the preparation method disclosed in Example 1 of the Chinese invention patent (publication number CN116885970 A), comprising the following steps:

[0064] (1) Take two electrodes (aluminum foil electrodes) and two films [perfluoroethylene propylene copolymer (FEP) films], cut them into a size of 10 cm × 5 cm in length and width, and stick the two electrodes on the surfaces of the two films [perfluoroethylene propylene copolymer (FEP) films] to form two electrode layers, and then place the two electrode layers opposite to each other;

[0065] (2) inserting a perfluoroethylene propylene copolymer (FEP) film between the electrode layer and the film layer in step (1) with a length and width of 10 cm × 5 cm, polishing both sides of the film with 20000 grit sandpaper, and then adding 20 μL of perfluoropolyether (PFPE) to form two oil layers;

[0066] (3) Two copper wires are used to connect the two electrode layers respectively and fixed with PTFE tape to serve as the lead-out. Then, a 16 cm × 12 cm long and wide PTFE tape is used to encapsulate and fix the lead-out portion of the copper wire. Silicone (Dow Corning734) is used to encapsulate and waterproof the lead-out portion to obtain a nanogenerator.

[0067] A nanogenerator prepared in Comparative Example 4 was fixed on a rectangular flagpole and placed in a water tank, and a cylinder with a diameter of 5 cm and a length of 30 cm was placed on the left side of the nanogenerator to obtain the water flow energy collection device of this comparative example.

[0068] Comparative Example 5

[0069] The nanogenerator is prepared according to the preparation method disclosed in Example 1 of the Chinese invention patent (publication number CN118199437A), comprising the following steps:

[0070] (1) Weighing barium titanate and bacterial nanocellulose at a mass ratio of 2.5:97.5, dispersing barium titanate in bacterial nanocellulose, and ultrasonically dispersing the solution by a cell crusher to form a uniform solution, then pouring the solution into a vacuum filtration device for filtration to form a film, and then placing the solution in a vacuum drying oven at 60° C. for 12 hours to obtain a positive friction layer film;

[0071] (2) Cutting the positive friction layer film and the negative friction layer polytetrafluoroethylene film obtained in step (1) into sizes of length × width = 12 cm × 8 cm, and then placing the two opposite to each other to perform contact and separation;

[0072] (3) spraying silver ink onto the surfaces of two perfluoroethylene-propylene copolymer film layers, and after drying and curing, cutting them into electrode layers with a size of length×width=12 cm×8 cm to form two electrode layers attached to the film layers;

[0073] (4) Compounding one electrode layer obtained in step (3) with the positive friction layer film, and compounding the other electrode layer with the negative friction layer polytetrafluoroethylene film; then using two copper wires to connect the two electrode layers respectively to play a lead-out role; then using PTFE tape with a length × width = 18 cm × 12 cm to package and fix, and using silicone (Dow Corning734) to waterproof the part where the copper wire is led out to obtain a nanogenerator.

[0074] A method for preparing a water flow energy collection device comprises the following steps:

[0075] (1) A 3D printer was used to print a ring (outer ring diameter of 15 cm, inner ring diameter of 10 cm) and a cylinder (diameter of 10 cm, height of 15 cm), and a circle of small balls (diameter of 0.5 cm) were printed at the bottom of the ring as the ring part and the cylinder part; then the ring part was placed on the top of the cylinder part to form a rotating ring structure; a fishtail shape was printed as the fishtail structure; finally, spring steel plates (size of length × width = 10 cm × 1 cm) were used on both sides of the rotating ring structure to connect the fishtail structure and the PVC leaf film (size of length × width = 20 cm × 15 cm);

[0076] (2) The three nanogenerators prepared in this comparative example were fixed in parallel in the fishtail structure, and then the nanogenerators were connected to the LED lights and underwater electronic sensor equipment inserted into the breadboard, and then the LED lights and underwater electronic sensor equipment were encapsulated with silicone water (Smooth-on Dragonskin20 and SYLGARD 184) to prepare a water flow energy harvesting device.

[0077] Performance Testing

[0078] The water flow energy harvesting devices prepared in Examples 1-4 and Comparative Examples 1-3 were immersed in water, and the output current and voltage were measured at 0.5 Hz and 80 mm displacement parameters. The results are shown in Table 1.

[0079] Table 1:

[0080] Current (μA) Voltage (V) Example 1 1.18 37.8 Example 2 0.13 7.81 Example 3 0.66 14.21 Example 4 0.28 4.82 Comparative Example 1 0.13 2.17 Comparative Example 2 0.88 24.42 Comparative Example 3 0.68 29.74

[0081] As shown in Table 1, the water flow energy harvesting devices prepared in Examples 1-4 all have good output performance, among which Example 1 has the best performance. The main reasons are: in Example 1, the mass ratio of titanium dioxide to polyvinylidene fluoride is 4:96, and the added titanium dioxide improves the surface roughness of the film while improving the dielectric properties of the film, thereby improving the output performance of the assembled nanogenerator; in Example 2, the mass ratio of titanium dioxide to polyvinylidene fluoride is 1:99, and the content of titanium dioxide is lower than that in Example 1, so the output performance of the assembled nanogenerator is lower than that in Example 1; in Examples 3 and 4, the mass ratios of titanium dioxide to polyvinylidene fluoride are 5:95 and 7:93 respectively, and the increase in the content of titanium dioxide causes the titanium dioxide nanoparticles to agglomerate in the prepared polyvinylidene fluoride film, which reduces the roughness of the film, thereby causing the output performance of the nanogenerator to be lower than that of Example 1.

[0082] Compared with Example 1, Comparative Example 1 and Comparative Example 2 respectively lead to a decrease in output performance due to the fact that titanium dioxide is not added to the negative friction film layer and barium titanate is used instead of titanium dioxide.

[0083] Compared with Example 1, the water flow energy collection device of Comparative Example 3 does not include a triangular bluff body and a truncated cone base during assembly, resulting in a significant decrease in power output performance. The main reasons are: Comparative Example 3 lacks a triangular bluff body and cannot utilize the vortex shedding generated by the water flow passing through the bluff body, so the output performance is low; at the same time, it lacks a rotating mechanism of the truncated cone and bluff body combination, and cannot better collect the water flow energy after the flow direction changes; while Example 1 can turn to the direction of the maximum flow velocity according to the changed flow velocity after the flow velocity changes, so as to better collect the mechanical energy in the water flow.

[0084] The water flow energy harvesting devices prepared in Example 1 and Comparative Examples 4-5 were pressurized to 0.1-20 MPaA in an autoclave, taken out and immersed in water, and the output current and voltage were measured at 0.5 Hz and 80 mm displacement parameters. The results are shown in Table 2.

[0085] Table 2:

[0086]

[0087] As shown in Table 2, the water flow energy collection device prepared in Example 1 can still generate electricity normally under a high pressure environment of 20MPaA; while the water flow energy collection devices prepared in Comparative Examples 4 and 5 cannot stably supply power under a high pressure environment, that is, they are not suitable for the high pressure environment of the deep sea. The main reason is that: in Comparative Example 4, a perfluoroethylene propylene copolymer (FEP) film with a length and width of 10cm×5cm is inserted between the polar layer and the film layer, and both sides of the film are polished with 20000 mesh sandpaper, and then 20μL of perfluoropolyether (PFPE) is added to form two oil layers. Compared with the addition of 20μL of perfluoropolyether (PFPE) between the negative friction film layer prepared in step (2) and the positive friction film layer prepared in step (3) in Example 1 to form an oil layer, the oil layer structure in Comparative Example 4 is more complicated. At the same time, PVDF (above 50MPa at room temperature) has a higher tensile strength than FEP (20-30MPa at room temperature). Therefore, in a deep-sea environment with high hydrostatic pressure, the oil layer structure is simpler, and the output performance and stability of Example 1 with better mechanical properties are better than those of Comparative Example 4. In Comparative Example 5, the ring, fishtail and cylinder in the water flow collection device use FDM 3D printing technology. The processing structure of this technology adopts the method of molten deposition, and the structure presents a multi-layer structure. Therefore, the bonding force between the layers is poor, and the overall density of the structure is also lower than that of the cut workpiece, which is difficult to adapt to the high hydrostatic pressure in the deep sea. At the same time, compared with the water flow collection device in Comparative Example 5, which uses a 3D printer to print rings and cylinders, and the rotating ring structure uses a spring steel plate to connect the fishtail structure, the water flow collection device in Example 1 uses a guide plate, a triangular blunt body and a truncated cone base cut by polytetrafluoroethylene. The three parts are made of the same material. The water flow collection device assembled will not cause mismatch due to the difference in mechanical properties under high hydrostatic pressure in the deep sea. Moreover, the components cut from polytetrafluoroethylene polymer block materials in Example 1 have a higher structural density than the components processed using FDM 3D technology in Comparative Example 5 and are more adaptable to the high hydrostatic pressure in the deep sea.

[0088] For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, without having to go through creative labor. Therefore, simple improvements made to the present invention by those skilled in the art based on the disclosure of the present invention should be within the protection scope of the present invention. The above embodiments are preferred embodiments of the present invention, and all processes similar to the present invention and equivalent changes made should belong to the protection scope of the present invention.

Claims

1. A nanogenerator, characterized in that: The nanogenerator has a symmetrical structure, and comprises, from top to bottom, an encapsulation film layer, an electrode layer, a positive friction film layer, an oil layer, a negative friction film layer, an electrode layer and an encapsulation film layer stacked in sequence, wherein the electrode layer is connected to a wire; and the negative friction film layer is a polyvinylidene fluoride film doped with titanium dioxide.

2. The nanogenerator according to claim 1, characterized in that: In the negative friction film layer, the mass ratio of titanium dioxide to polyvinylidene fluoride is (1-7): (93-99).

3. The nanogenerator according to claim 1, characterized in that: The positive friction film layer is selected from bacterial nanocellulose film.

4. The nanogenerator according to claim 1, characterized in that: The encapsulation film layer is selected from polytetrafluoroethylene film.

5. The nanogenerator according to claim 1, characterized in that: The electrode layer is aluminum foil, silver foil or copper foil.

6. The nanogenerator according to claim 1, characterized in that: The components of the oil layer include at least one of perfluoropolyether, squalane and paraffin oil.

7. A method for preparing a nanogenerator according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Two electrodes are taken and pasted on the surfaces of two packaging films respectively, with the surfaces of the two electrodes facing each other, to form two electrode layers and two packaging film layers; (2) coating the surfaces of the two electrode layers in step (1) with a titanium dioxide-doped polyvinylidene fluoride solution and a bacterial nanocellulose solution, respectively, to form a negative friction film layer and a positive friction film layer; and then adding perfluoropolyether, squalane or paraffin oil between the negative friction film layer and the positive friction film layer to form an oil layer; (3) Two electrode layers are connected respectively with two wires and packaged to obtain the nanogenerator.

8. The method for preparing a nanogenerator according to claim 7, characterized in that: In step (2), the amount of perfluoropolyether, squalane or paraffin oil added is 10-100 μL.

9. A water flow energy collection device, characterized in that: It comprises the nanogenerator, guide plate, triangular bluff body and truncated cone base as described in any one of claims 1 to 6; the nanogenerator is arranged at the tail of the guide plate, and the triangular bluff body is installed on the truncated cone base; the guide plate is connected to the triangular bluff body and can drive the triangular bluff body to rotate on the truncated cone base under the action of water flow.

10. The water flow energy collection device according to claim 9, characterized in that: The guide plate, the triangular bluff body and the truncated cone base are all made of polytetrafluoroethylene.

Images