Friction nanometer generator based on friction layer of sandwich structure

Abstract

The invention discloses a friction nano-generator based on a friction layer of a sandwich structure, which comprises a charge output device and a main friction nano-generator which are connected with each other, and the friction layer of the main friction nano-generator adopts the friction layer of the sandwich structure; the friction layer of the sandwich structure comprises a first high-molecular material layer, a metal layer and a second high-molecular material layer, the upper face and the lower face of the metal layer are connected with the first high-molecular material layer and the second high-molecular material layer in a gapless mode respectively, and the periphery of the metal layer is sealed and does not make contact with air. The problems that an existing friction nanometer generator is complex in structure, cannot effectively store charges, and is low in response speed can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of friction nanogenerators, and in particular to a friction nanogenerator based on a sandwich structure friction layer. Background Art

[0002] With the continuous increase in global energy demand and the increasingly severe environmental problems, the development of new sustainable energy technologies has become one of the hot spots in current scientific research and industrial applications. As an energy harvester based on the coupling of triboelectric charging and electrostatic induction, the triboelectric nanogenerator has been widely used in small sensors, wearable devices, environmental monitoring, and self-powered systems because of its high energy conversion efficiency, flexibility, and environmental friendliness. Its electrical output performance is proportional to the amount of charge carried by the surface friction layer. Therefore, in order to increase the charge carried by the two materials, researchers have adopted a variety of strategies. For example, by studying the difference in electronegativity of common friction materials, we can find material pairs with large charge transfer; by constructing microscopic or nanoscale structures on the surface of friction materials to increase the friction area and thus increase the amount of charge accumulation; by adding polar substances or nanoparticles to the material, the surface of the friction material obtains a polarization effect, thereby improving its charge transfer ability; the working environment of the triboelectric nanogenerator is set to a vacuum to reduce the recombination of charges with charged particles in the air and thus reduce charge loss. However, since friction materials usually have good insulation properties, this will cause the charges to be unevenly distributed on their surface, limiting the amount of charge they can carry and weakening the electrical output capacity of the friction nanogenerator to a certain extent.

[0003] Since metals have a high free electron density and excellent electrical conductivity, they can effectively conduct and evenly distribute charges in materials, making metals far superior to polymer materials in carrying charges. Therefore, related studies have proposed a friction nanogenerator with a charge pump structure. The main idea of ​​this structure is to connect the electrical output generated by a friction nanogenerator (called a "pump friction nanogenerator") to the friction layer of another friction nanogenerator (called a "main friction nanogenerator"), so that the friction electrification process is replaced by the pumped charge. Since the friction layer of the main friction nanogenerator is made of metal, the more charges carried will greatly improve its output performance. However, this method also has some limitations. First, the electrode that stores the friction charge is directly exposed to the air and is easily affected by the humidity of the environment. At the same time, the carried charge will also directly recombine with the charged particles in the air, thereby increasing the loss of charge. Secondly, the shape of the electrode of the friction nanogenerator needs to be carefully designed to ensure the electrical output performance, and its structure is also more complex.

[0004] In order to design a more concise friction nanogenerator, Jian et al. proposed a vertical contact separation friction nanogenerator. The design adopts a cascade method to input the lower output voltage of the pump friction nanogenerator II into the pump friction nanogenerator I through a rectifier bridge, thereby improving its electrical output performance. Then, the higher output of the pump friction nanogenerator I is input to the main friction nanogenerator again through a rectifier bridge. 2 The friction nanogenerator finally makes the short-circuit current and open-circuit voltage of the main friction nanogenerator reach 3mA and 2300V respectively. In this structure, since the charge storage layer and output layer of the pump friction nanogenerator I and the main friction nanogenerator are the same metal layer, the charge input from the previous level will be directly output to the next level, resulting in the metal layer being unable to effectively store the friction charge. In addition, the short-circuit current of the pump friction nanogenerator II, the pump friction nanogenerator I and the main friction nanogenerator when working alone are 1.62mA, 0.69mA and 1.8mA, respectively, and the open-circuit voltage is 320V, 1300V and 1300V, respectively. Through the cascade method, although the overall short-circuit current and open-circuit voltage reach 3mA and 2300V, however, this improvement is achieved at the expense of the output of the first two levels, and the overall electrical output performance is not even as good as the sum of the electrical outputs of the three friction nanogenerators when working alone. Therefore, this scheme is unreasonable. Summary of the invention

[0005] In view of the above problems, the present invention aims to provide a friction nanogenerator based on a sandwich structure friction layer.

[0006] The technical solution of the present invention is as follows:

[0007] A friction nanogenerator based on a sandwich structure friction layer, comprising a charge output device and a main friction nanogenerator connected to each other, wherein the friction layer of the main friction nanogenerator adopts a sandwich structure friction layer;

[0008] The sandwich structure friction layer includes a polymer material layer 1, a metal layer, and a polymer material layer 2. The upper and lower surfaces of the metal layer are connected to the polymer material layer 1 and the polymer material layer 2 without gaps, respectively, and the metal layer is sealed on all sides and has no contact with air.

[0009] Preferably, the polymer material layer 1 and the polymer material layer 2 are made of polyimide, polyethylene, polypropylene or polyvinylidene fluoride respectively.

[0010] Preferably, when the polymer material layer 1 is made of polyimide and the polymer material layer 2 is made of polyvinylidene fluoride, the sandwich structure friction layer is prepared by the following steps:

[0011] A PI film is made of polyimide, and metal is sprayed on the upper surface of the PI film to form the metal layer;

[0012] A PVDF solution is prepared by using polyvinylidene fluoride, and the PVDF solution is scraped onto the upper surface of the PI film containing the metal layer, and dried to form a PVDF film;

[0013] The PVDF film is connected to the PI film and the metal layer without a gap, and the metal layer is isolated from contact with air around the metal layer through the portion connected to the upper surface of the PI film.

[0014] Preferably, the PVDF solution also includes graphene oxide.

[0015] Preferably, the metal layer is made of copper or silver.

[0016] Preferably, when the charge output device outputs alternating current, the charge output device is connected to the main friction nanogenerator via a rectifier bridge; when the charge output device outputs direct current, the charge output device is directly connected to the main friction nanogenerator.

[0017] Preferably, the main friction nanogenerator comprises two substrates with the same structure and arranged opposite to each other, the substrates comprise a friction layer and a conductive layer connected to each other, and the friction layers of the two substrates are arranged opposite to each other.

[0018] Preferably, the conductive layer is made of aluminum foil or copper foil.

[0019] Preferably, the substrate further comprises an insulating fixed support plate connected to the conductive layer.

[0020] Preferably, the charge output device adopts a pump friction nanogenerator.

[0021] The beneficial effects of the present invention are:

[0022] 1. The sandwich structure friction layer of the present invention can store relatively high friction charges, and a simple vertical contact separation friction nanogenerator can be designed based on the sandwich structure friction layer.

[0023] 2. The main friction nanogenerator of the present invention can achieve high energy conversion efficiency under extremely low frequency and extremely low output of the pump friction nanogenerator, and the short-circuit current, open-circuit voltage and charge can reach a maximum of 51.61μA, 550V and 218.38nC.

[0024] 3. The main friction nanogenerator described in the present invention has a fast response capability and excellent charge retention ability: when the pump friction nanogenerator is switched from an unopened state to an opened state, the short-circuit current, open-circuit voltage and charge can all reach the ideal output state within 1 to 2 seconds; when the pump friction nanogenerator is switched from an opened state to an unopened state, the main friction nanogenerator decreases from the ideal output to a lower output after 40 to 45 seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 This is a schematic diagram of the structure of the sandwich structure friction layer of the present invention;

[0027] Figure 2 It is a schematic structural diagram of the main friction nanogenerator of the present invention;

[0028] Figure 3 It is a schematic diagram of the structure of the friction nanogenerator of the present invention;

[0029] Figure 4 Schematic diagram of the effect of different PVDF film thicknesses on the main friction nanogenerator in a specific embodiment; wherein (a) is the short-circuit current, (b) is the open-circuit voltage, and (c) is the charge;

[0030] Figure 5 Schematic diagram of the effect of different pump triboelectric nanogenerator operating frequencies on the main triboelectric nanogenerator in a specific embodiment; wherein (a) is the short-circuit current, (b) is the open-circuit voltage, and (c) is the charge;

[0031] Figure 6 Schematic diagram of the test results of the rapid response capability and charge retention capability of the main friction nanogenerator in a specific embodiment; wherein (a)-(c) are the short-circuit current, open-circuit voltage, and charge of the pump friction nanogenerator when it switches from an unopened state to an open state, respectively; (d) and (e) are the short-circuit current and charge of the pump friction nanogenerator when it switches from an open state to an unopened state, respectively;

[0032] Figure 7 Schematic diagram of the output test results of the main friction nanogenerator under different loads in a specific embodiment; wherein (a) is the output current and output voltage under different loads, and (b) is the output power under different loads. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, in the absence of conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other. It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as those generally understood by those of ordinary skill in the art to which this application belongs. The words "including" or "comprising" and the like used in the disclosure of the present invention mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0034] like Figure 1-3 As shown, the present invention provides a friction nanogenerator based on a sandwich structure friction layer, comprising a connected charge output device and a main friction nanogenerator, wherein the friction layer of the main friction nanogenerator adopts a sandwich structure friction layer;

[0035] The sandwich structure friction layer includes a polymer material layer 1, a metal layer, and a polymer material layer 2. The upper and lower surfaces of the metal layer are connected to the polymer material layer 1 and the polymer material layer 2 without gaps, respectively, and the metal layer is sealed on all sides and has no contact with air.

[0036] In a specific embodiment, the polymer material layer 1 and the polymer material layer 2 are respectively made of polyimide, polyethylene, polypropylene or polyvinylidene fluoride. It should be noted that the polymer material of this embodiment is only the preferred polymer material of the present invention, and other insulating materials in the prior art can also be applied to the present invention.

[0037] In a specific embodiment, when the polymer material layer 1 is made of polyimide and the polymer material layer 2 is made of polyvinylidene fluoride, the sandwich structure friction layer is prepared by the following steps:

[0038] A PI film is made of polyimide, and metal is sprayed on the upper surface of the PI film to form the metal layer;

[0039] A PVDF solution is prepared by using polyvinylidene fluoride, and the PVDF solution is scraped onto the upper surface of the PI film containing the metal layer, and dried to form a PVDF film;

[0040] The PVDF film is connected to the PI film and the metal layer without a gap, and the metal layer is isolated from contact with air around the metal layer through the portion connected to the upper surface of the PI film.

[0041] In a specific embodiment, the PVDF solution is prepared by adding PVDF powder to an organic solvent, and the concentration of the PVDF solution is 10%. It should be noted that the concentration of the PVDF solution in this embodiment is the preferred concentration of the present invention, and the concentration can be reduced or increased to a certain extent, but the concentration cannot be too large or too small. If the concentration is too large, the PVDF solution is not easy to scrape, and the PVDF membrane is easily damaged during drying; if the concentration is too small, the PVDF membrane will be thin, and the PVDF membrane cannot be thickened by scraping multiple times at this time, because during the scraping again, the solvent in the PVDF solution will dissolve the dried PVDF membrane again.

[0042] In a specific embodiment, the PVDF solution also includes graphene oxide. Optionally, the amount of graphene oxide is 1.25% of the mass of PVDF powder in the PVDF solution. In this embodiment, the addition of graphene oxide can increase the dielectric constant of the material and increase the surface charge density of the friction material. It should be noted that the amount of graphene oxide in this embodiment is only the preferred amount of the present invention. The inventor has made an embodiment of 0-2% dosage. When graphene oxide is not added, the present invention can still achieve high energy conversion efficiency under extremely low frequency and extremely low output conditions of the pump friction nanogenerator; when graphene oxide is added, the surface charge density of the friction material shows a trend of first increasing and then decreasing. When the dosage is 1.25%, the increase in the surface charge density of the friction material is the largest.

[0043] In a specific embodiment, the metal layer is made of copper or silver. It should be noted that the metal layer needs to be formed by spraying metal paint on one of the polymer material layers, and then completely sealed with another polymer material layer to isolate the metal layer from the air. The inventors set a formed metal layer (aluminum foil) on one of the polymer material layers, and then completely sealed with another polymer material layer to isolate the metal layer from the air, but the sandwich structure friction layer made in this way cannot achieve the technical effect that the sandwich structure friction layer described in the present invention can store higher friction charges. In addition, the preferred metal raw material of this embodiment is the raw material that can be directly purchased for metal spray paint, and other metal raw materials that can be sprayed to form a metal layer are also applicable to the present invention.

[0044] In a specific embodiment, when the charge output device outputs alternating current, the charge output device is connected to the main friction nanogenerator through a rectifier bridge; when the charge output device outputs direct current, the charge output device is directly connected to the main friction nanogenerator.

[0045] In a specific embodiment, the main friction nanogenerator includes two substrates with the same structure and arranged opposite to each other, the substrates include a friction layer and a conductive layer connected to each other, and the friction layers of the two substrates are arranged opposite to each other.

[0046] It should be noted that when the materials of the two polymer material layers of the sandwich structure friction layer are inconsistent, a polymer material layer with better insulation is selected to be connected to the conductive layer, which can reduce the charge loss caused by the conductive layer and the friction layer carrying different charges.

[0047] In a specific embodiment, the conductive layer is made of aluminum foil or copper foil. It should be noted that the conductive layer of this embodiment is only a preferred conductive layer, and conductive layers made of other conductive materials in the prior art can also be applied to the present invention.

[0048] In a specific embodiment, the substrate further comprises an insulating fixing support plate connected to the conductive layer. Optionally, the insulating fixing support plate is an acrylic plate.

[0049] In a specific embodiment, the charge output device adopts a pump friction nanogenerator. It should be noted that the charge output device mainly provides the friction charge required in the electrostatic induction process for the main friction nanogenerator. Various pump friction nanogenerators capable of generating electricity in the prior art can be applied to the present invention. The pump friction nanogenerator is a prior art, and the specific structure is not repeated here.

[0050] Example 1

[0051] A friction nanogenerator is prepared by the following steps:

[0052] (1) Preparation of the copper layer template: Take a 15×15 cm 2 PET film, use a utility knife to cut out a 4×4 cm 2 square hole.

[0053] (2) Preparation of the copper layer: Take a 15×15 cm 2 The PI film is overlapped with the metal copper layer template and the PI film, and placed at 45° to the horizontal direction. The conductive copper spray paint is sprayed at a distance of 20 cm from the PI film for 3s to 5s. The sprayed PI film is placed in a 60°C oven to dry for 30min.

[0054] (3) Preparation of PVDF solution: 25 mg of graphene oxide was added to 18 g of dimethylformamide solution and ultrasonicated for 1 h; 2 g of PVDF powder was added to the above solution and stirred at 60 °C for 12 h.

[0055] (4) Preparation of common friction layer: The PVDF solution prepared in step (3) was scraped onto the PI film without a metal copper layer to form a 750 μm liquid film, and then dried in an oven at 60° C. for 1 h. The thickness of the film after drying was 30 μm.

[0056] (5) Preparation of the pump friction nanogenerator: Two 4×4 cm 2 The aluminum foil is pasted on the surface of the acrylic plate, and the ordinary friction layer prepared in step (4) is pasted on the surface of one of the aluminum foils to obtain substrate one. The other aluminum foil is not pasted with the ordinary friction layer to obtain substrate two. The ordinary friction layer of substrate one is arranged opposite to the aluminum foil of substrate two to obtain the pump friction nanogenerator.

[0057] (6) Preparation of sandwich structure friction layer: The PVDF solution prepared in step (3) was scraped onto the PI film containing the metallic copper layer prepared in step (2) to form a 500 μm liquid film, and then dried in an oven at 60° C. for 1 h. The thickness of the film after drying was 20 μm.

[0058] (7) Preparation of the main triboelectric nanogenerator: Two 4×4 cm 2 The aluminum foil is pasted on the surface of the acrylic plate, and the two sandwich structure friction layers prepared in step (4) are pasted on the surface of the aluminum foil to obtain two substrates. The PVDF films of the two substrates are arranged opposite to each other to obtain the main friction nanogenerator.

[0059] (8) Connecting the pump friction nanogenerator and the main friction nanogenerator via a rectifier bridge to obtain the friction nanogenerator.

[0060] Example 2

[0061] Different from Example 1, the thickness of the liquid film in step (6) of this example is 750 μm, and the thickness of the film after drying is 30 μm.

[0062] Example 3

[0063] Different from Example 1, the thickness of the liquid film in step (6) of this example is 1000 μm, and the thickness of the film after drying is 40 μm.

[0064] Test Case

[0065] The working environment of the pump triboelectric nanogenerator and the main triboelectric nanogenerator of each triboelectric nanogenerator in Examples 1-3 was set to 6N and 8Hz, and the output performance of each triboelectric nanogenerator was measured using a Keithley 6514 electrometer. The working environment of the pump triboelectric nanogenerator of the triboelectric nanogenerator in Example 2 was also set to 8Hz, 4Hz, and 2Hz respectively, and other working environment conditions remained unchanged, and the influence of the pump triboelectric nanogenerator on the main triboelectric nanogenerator at different working frequencies was measured. The test results are shown in Figure 2. Figure 4-7shown.

[0066] from Figure 4 It can be seen that under the same working conditions, the triboelectric nanogenerators with different PVDF film thicknesses have relatively excellent output performance. When the PVDF film thickness is 30μm, the main triboelectric nanogenerator prepared has the best output performance, and its short-circuit current, open-circuit voltage and charge can reach up to 51.61μA, 550V and 218.38nC.

[0067] from Figure 5 It can be seen that the output performance of the main friction nanogenerator described in the present invention is minimally affected by the pump friction nanogenerator. This is because the friction layer of the sandwich structure described in the present invention has good charge retention ability. When the charge is saturated, increasing the output of the pump friction nanogenerator will hardly increase the charge carried by the copper layer of the friction layer.

[0068] from Figure 6 It can be seen that when the pump friction nanogenerator switches from the unturned state to the turned-on state, the short-circuit current, open-circuit voltage and charge of the main friction nanogenerator can reach the ideal output state within 1 to 2 seconds; when the pump friction nanogenerator switches from the turned-on state to the unturned state, the main friction nanogenerator decreases from the ideal output to a lower output after 40 to 45 seconds.

[0069] from Figure 7 It can be seen that as the load resistance increases, the output current of the main friction nanogenerator gradually decreases and the output voltage gradually increases, and both change most significantly in the resistance range of 100kΩ to 100MΩ. When the external load resistance is 7.5MΩ, the main friction nanogenerator has the maximum output power, and its power density is 6.91W / m 2 .

[0070] The above description is only a representative embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, uses the above-disclosed technical contents to make some changes or modifications to the embodiments are equivalent embodiments of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A friction nanogenerator based on a sandwich structure friction layer, characterized in that: It comprises a connected charge output device and a main friction nanogenerator, wherein the friction layer of the main friction nanogenerator adopts a sandwich structure friction layer; The sandwich structure friction layer includes a polymer material layer 1, a metal layer, and a polymer material layer 2. The upper and lower surfaces of the metal layer are connected to the polymer material layer 1 and the polymer material layer 2 without gaps, respectively, and the metal layer is sealed on all sides and has no contact with air.

2. The friction nanogenerator based on the sandwich structure friction layer according to claim 1 is characterized in that: The polymer material layer 1 and the polymer material layer 2 are respectively made of polyimide, polyethylene, polypropylene or polyvinylidene fluoride.

3. The friction nanogenerator based on the sandwich structure friction layer according to claim 2 is characterized in that: When the polymer material layer 1 is made of polyimide and the polymer material layer 2 is made of polyvinylidene fluoride, the sandwich structure friction layer is prepared by the following steps: A PI film is made of polyimide, and metal is sprayed on the upper surface of the PI film to form the metal layer; A PVDF solution is prepared by using polyvinylidene fluoride, and the PVDF solution is scraped onto the upper surface of the PI film containing the metal layer, and dried to form a PVDF film; The PVDF film is connected to the PI film and the metal layer without a gap, and the metal layer is isolated from contact with air around the metal layer through the portion connected to the upper surface of the PI film.

4. The friction nanogenerator based on the sandwich structure friction layer according to claim 3 is characterized in that: The PVDF solution also includes graphene oxide.

5. The friction nanogenerator based on the sandwich structure friction layer according to claim 1 is characterized in that: The metal layer is made of copper or silver.

6. The friction nanogenerator based on the sandwich structure friction layer according to claim 1 is characterized in that: When the charge output device outputs alternating current, the charge output device is connected to the main friction nanogenerator via a rectifier bridge; when the charge output device outputs direct current, the charge output device is directly connected to the main friction nanogenerator.

7. The friction nanogenerator based on the sandwich structure friction layer according to claim 1 is characterized in that: The main friction nanogenerator comprises two substrates with the same structure and arranged opposite to each other. The substrates comprise a friction layer and a conductive layer connected to each other. The friction layers of the two substrates are arranged opposite to each other.

8. The friction nanogenerator based on the sandwich structure friction layer according to claim 7 is characterized in that: The conductive layer is made of aluminum foil or copper foil.

9. The friction nanogenerator based on the sandwich structure friction layer according to claim 7, characterized in that: The substrate also includes an insulating fixed support plate connected to the conductive layer.

10. The triboelectric nanogenerator based on a sandwich structure friction layer according to any one of claims 1 to 9, characterized in that: The charge output device adopts a pump friction nanogenerator.

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