A triboelectric nanogenerator and its power generation method, and a flexible sensor

Abstract

This invention provides a triboelectric nanogenerator and its power generation method, as well as a flexible sensor, to provide a triboelectric nanogenerator capable of directly outputting direct current, thereby avoiding the power loss problem caused by converting alternating current to direct current through a rectifier in the prior art. The triboelectric nanogenerator includes: a first electrode layer, a second electrode layer, and a friction layer; wherein the friction layer is disposed between the first electrode layer and the second electrode layer, and the friction layer is attached to the surface of the first electrode layer, with a fluid layer flowing through one side of the friction layer opposite to the second electrode layer.

Description

Technical Field

[0001] This invention relates to the field of triboelectric nanogenerator technology, and more particularly to a triboelectric nanogenerator and power generation method, as well as a flexible sensor. Background Technology

[0002] Currently, to address the energy crisis and environmental pollution caused by the combustion of fossil fuels, collecting and utilizing renewable energy sources (such as wind energy, ocean energy, tidal energy, and biomechanical energy) has become a major development area. There are two main methods for collecting renewable energy: one targets high-frequency energy, utilizing Faraday's law of electromagnetic induction combined with the energy's inherent physical properties; the other targets low-frequency and ultra-low-frequency energy, converting mechanical energy into electrical energy output through triboelectric charging and electrostatic induction coupling.

[0003] The second method described above generates electricity through triboelectric nanogenerators. Due to the principle of electrostatic induction, the triboelectric nanogenerator operates by moving charges back and forth between two electrodes, resulting in alternating current (AC) energy after energy conversion. Therefore, an external rectifier is needed to convert the AC to DC output, powering energy storage devices or directly driving small electronic devices. However, the external rectifier not only causes energy loss in the triboelectric nanogenerator output, but its large rigidity and size also make it difficult to apply the nanogenerator to flexible electronic devices. Therefore, current technology lacks a triboelectric nanogenerator that can directly output DC to avoid the energy loss problem caused by rectifiers. Summary of the Invention

[0004] This invention provides a triboelectric nanogenerator and a method for generating electricity, as well as a flexible sensor, to provide a triboelectric nanogenerator that can directly output direct current, thereby avoiding the power loss problem caused by converting alternating current to direct current through a rectifier in the prior art.

[0005] In a first aspect, embodiments of this application provide a triboelectric nanogenerator, comprising:

[0006] A first electrode layer, a second electrode layer, and a friction layer; wherein the friction layer is disposed between the first electrode layer and the second electrode layer, and the friction layer is attached to the surface of the first electrode layer, and a fluid layer flows through one side of the friction layer opposite to the second electrode layer.

[0007] In the triboelectric nanogenerator provided in this application embodiment, the characteristic that the ion-driven current is much greater than the contact displacement current allows the nanogenerator to continuously output direct current flowing from the second electrode layer to the first electrode layer. Simultaneously, during operation, the triboelectric layer is replenished with charge in situ by the fluid layer flowing across its surface. This avoids wear and tear on the triboelectric layer while ensuring a large short-circuit current (not less than 20 μA) is output at a relative motion frequency of 1.0 Hz, thus achieving a high energy output rate.

[0008] In one possible implementation, the friction layer and the second electrode layer are staggered, such that the fluid layer completely covers one side surface of the friction layer opposite to the second electrode layer.

[0009] In one possible implementation, the thickness of the friction layer is no greater than 1 mm.

[0010] In one possible implementation, the materials of the first electrode layer and the second electrode layer are each independently selected from at least one of the following: alloy conductive materials, composite metal materials, carbon materials, and organic conductive materials.

[0011] In one possible implementation, the material of the friction layer is selected from at least one of: polytetrafluoroethylene, fluororubber, polyvinylidene fluoride, polyimide, polyethylene, polystyrene, polyurethane rubber, cellulose, polypropylene, cis-1,4-polyisoprene, synthetic fiber, polymethyl methacrylate, polyvinylidene fluoride, and perfluoroethylene propylene copolymer.

[0012] In one possible implementation, the fluid layer is selected from at least one of: deionized water, charged deionized water, aqueous lithium chloride solution, aqueous hydrogen chloride solution, lithium bis(trifluoromethanesulfonyl)imide, aqueous 1-ethyl-3-methylimidazolium chloride solution, and organic solutions.

[0013] In one possible implementation, the side surface of the friction layer relative to the second electrode layer is a hydrophilic surface; preferably, the side surface of the friction layer relative to the second electrode layer is the hydrophilic surface obtained by plasma sputtering and / or laser engraving.

[0014] In one possible implementation, the fluid layer is subjected to ultrasonic vibration at a frequency of not less than 500 Hz, thereby increasing the positive charge content in the fluid layer.

[0015] Secondly, embodiments of this application provide a method for generating electricity using a triboelectric nanogenerator based on the first aspect and any possible implementation, comprising:

[0016] The frequency of relative motion between the triboelectric nanogenerator's triboelectric layer and the second electrode layer is kept no greater than 10 Hz to output direct current; wherein,

[0017] The frequency of relative motion refers to the frequency at which the friction layer and the second electrode layer periodically contact and separate; when the friction layer separates from the second electrode layer, the fluid layer flows on the surface of the friction layer on the side opposite to the second electrode layer, and there is no contact between the fluid layer and the second electrode layer; when the friction layer contacts the second electrode layer, the surface of the friction layer coincides with the surface of the second electrode layer.

[0018] Thirdly, embodiments of this application provide a flexible sensor, including:

[0019] The triboelectric nanogenerator described in the first aspect and any possible implementation thereof. Attached Figure Description

[0020] Figure 1 A cross-sectional view of a triboelectric nanogenerator provided in an embodiment of this application;

[0021] Figure 2 This is a schematic diagram illustrating the state of a triboelectric nanogenerator during the power generation process, as provided in an embodiment of this application.

[0022] Figure 3 A cross-sectional view of another triboelectric nanogenerator provided in an embodiment of this application;

[0023] Figure 4 The equivalent circuit diagram of the DC triboelectric nanogenerator based on the variable supercapacitor structure provided in this application;

[0024] Figure 5 The equivalent circuit diagram of a triboelectric nanogenerator in the prior art is shown below.

[0025] Figure 6 The DC signal diagram obtained by performing a short-circuit current test on Example 1 at a relative motion frequency of 1.0 Hz, which is provided for the embodiments of this application;

[0026] Figure 7 The DC signal diagram obtained by performing a short-circuit current test on Example 2 at a relative motion frequency of 1.0 Hz, which is provided for the embodiments of this application;

[0027] Figure 8 The DC signal diagram obtained by performing a short-circuit current test on Example 3 at a relative motion frequency of 1.0 Hz, which is provided for the embodiments of this application;

[0028] Figure 9 The DC signal diagram obtained by performing a short-circuit current test on Example 4 at a relative motion frequency of 1.0 Hz, which is provided for the embodiments of this application;

[0029] Figure 10The DC signal diagram obtained by performing a short-circuit current test on Example 4 at a relative motion frequency of 10.0 Hz, which is provided for the embodiments of this application;

[0030] Wherein, 100—first electrode layer; 200—second motor layer; 300—friction layer; 400—fluid layer; 500—device to be powered; 600—AC power supply; 700—variable supercapacitor; 800—variable capacitor. Detailed Implementation

[0031] To address the lack of a nanogenerator that directly outputs direct current in existing technologies, this application provides a triboelectric nanogenerator. Please refer to [link / reference needed]. Figure 1 The triboelectric nanogenerator includes a first electrode layer 100, a second electrode layer 200, and a triboelectric layer 300.

[0032] A friction layer is disposed between the first electrode layer 100 and the second electrode layer 200, and the friction layer 300 is attached to the surface of the first electrode layer 100. A fluid layer flows through one side of the friction layer 300 opposite to the second electrode layer 200. The area of ​​the side of the friction layer 300 opposite to the surface of the second electrode layer 200 is the same as the area of ​​the side of the second electrode layer 200 opposite to the friction layer 300. Preferably, the contact surface area between the friction layer 300 and the first electrode layer 100 is the same.

[0033] In the aforementioned triboelectric nanogenerator, the triboelectric layer 300 is an electronegative material. When the solution 400 flows over the surface of the triboelectric layer 300, the surface of the triboelectric layer 300 adsorbs positive charges from the fluid layer 400. As the fluid layer 400 continues to flow over the surface of the triboelectric layer 300, the surface of the triboelectric layer 300 becomes rich in layered positive charges. Correspondingly, negative charges accumulate above the layered positive charges, and these negative charges also form a layered arrangement. This creates an "electric double layer" structure at the interface between the triboelectric layer 300 and the fluid layer 400, resulting in a built-in electric field between them. (Please refer to [reference needed]). Figure 1 Obviously, the longer the fluid layer 400 flows over the surface of the friction layer 300, the more positive and negative charges there are in the electric double layer, and the stronger the built-in electric field between them.

[0034] Furthermore, when the second electrode layer 200 and the friction layer 300 move relative to each other, and the surfaces of the second electrode layer 200 and the friction layer 300 come into contact, please refer to... Figure 2When the fluid layer 400 no longer flows through the friction layer 300, the aforementioned built-in electric field is destroyed, and the negative charge layer in the "double electric layer" structure disappears. The positive charge is transferred to the contact surface between the second electrode layer 200 and the friction layer 300 under the action of ion diffusion, thereby forming an ion-driven current. That is, the positive charge moves directionally from the second electrode layer 200 to the first electrode layer 100 through the external circuit.

[0035] Meanwhile, because the friction layer 300 is an electronegative material, it has a stronger electron-withdrawing ability during the contact electrification process with the second electrode layer 200. Therefore, under the contact electrification effect, an electron layer accumulates on the surface of the friction layer 300, resulting in a contact displacement current between the first electrode layer 100 and the second electrode layer 200. This contact displacement current flows out from the first electrode layer 100 and through the external circuit to the second electrode layer 200.

[0036] It is worth noting that although the ion-driven current and the contact displacement current are in opposite directions, the ion-driven current is much higher than the contact displacement current (the ratio of the former to the latter is about 50:1). Therefore, the current provided by the nanogenerator still flows from the second electrode layer 200 through the power supply device 500 in the external circuit to the first electrode layer 100.

[0037] Furthermore, when the friction layer 300 and the second electrode layer 200 separate again, since ion diffusion has been largely completed during the contact phase, no charge transfer occurs when they separate because the number of positive charges on their surfaces is the same. That is, no ion-driven current is generated at this time. Only under electrostatic induction is a separation displacement current generated, which is opposite in direction to the contact displacement current. Therefore, only a separation displacement current is generated during the separation phase after contact between the friction layer 300 and the second electrode layer 200, and its direction is the same as the current direction during the contact phase: both flow out from the second electrode layer 200, through the external circuit and the device to be powered 500, and flow to the first electrode layer 100.

[0038] The aforementioned friction layer 300 and the second electrode layer 200 can be arranged facing each other, and the distance between the friction layer 300 and the second electrode layer 200 is greater than the thickness of the fluid layer 400, so as to ensure that when the friction layer 300 and the second electrode layer 200 are separated, a potential difference is generated between the friction layer 300 and the second electrode layer 200, and the second electrode layer 200 is not affected by the built-in electric field between the friction layer 300 and the fluid layer 400.

[0039] Furthermore, in this embodiment, the triboelectric nanogenerator mainly generates electricity through the contact and separation between the triboelectric layer 300 and the second electrode layer 200. Therefore, in one embodiment of this application, the triboelectric layer 300 and the second electrode layer 200 can also be staggered so that the fluid layer 400 completely covers the surface of the triboelectric layer on the side opposite to the second electrode layer 200. Please refer to [reference needed]. Figure 3 .

[0040] Furthermore, both the first electrode layer 100 and the second electrode layer 200 are conductors. In one embodiment of this application, the first electrode layer 100 and the second electrode layer 200 are each independently selected from at least one of: alloy conductive materials, composite metal materials, carbon materials, and organic conductive materials.

[0041] Furthermore, the material of the aforementioned friction layer 300 is selected from at least one of the following: polytetrafluoroethylene, fluororubber, polyvinylidene fluoride, polyimide, polyethylene, polystyrene, polyurethane rubber, cellulose, polypropylene, cis-1,4-polyisoprene, synthetic fiber, polymethyl methacrylate, polyvinylidene fluoride, and perfluoroethylene-propylene copolymer. The cellulose can be photocopy paper. The thickness of the friction layer is no greater than 1 mm.

[0042] Furthermore, the fluid layer 400 is selected from at least one of: deionized water, charged deionized water, aqueous lithium chloride solution, aqueous hydrogen chloride solution, lithium bis(trifluoromethanesulfonyl)imide, aqueous 1-ethyl-3-methylimidazolium chloride solution, and organic solution.

[0043] Furthermore, as the fluid layer 400 flows through the friction layer 300, increasing the hydrophilicity of the friction layer 300 is beneficial for increasing its ability to adsorb positive charges. It also enhances the electron-withdrawing ability of the friction layer 300 during contact electrification, thereby increasing the current provided by the triboelectric nanogenerator per unit time. Therefore, in one embodiment of this application, the surface of the friction layer 300 relative to the second electrode layer 200 is a hydrophilic surface, which can be obtained through plasma sputtering and / or laser engraving.

[0044] Furthermore, in order to enable the friction layer 300 to acquire more positive charge per unit time when the fluid layer 400 flows through it, in one embodiment of this application, the fluid layer 400 is subjected to ultrasonic vibration at a frequency of not less than 500 Hz, so that the solution or solvent corresponding to the fluid layer 400 can have more sufficient contact with the air, thereby causing triboelectric charging between the fluid layer 400 and the air, and increasing the positive charge content in the fluid layer 400. The preferred ultrasonic vibration frequency here is 2000 Hz.

[0045] Based on the same inventive concept, this application also provides a method for generating electricity based on the above-mentioned triboelectric nanogenerator, the method comprising:

[0046] The frequency of relative motion between the triboelectric nanogenerator's triboelectric layer 300 and the second electrode layer 200 is kept to no more than 10 Hz in order to output direct current.

[0047] The frequency of relative motion refers to the frequency at which the friction layer 300 and the second electrode layer 200 periodically contact and separate. When the friction layer 300 separates from the second electrode layer 200, the fluid layer 400 flows on the surface of the friction layer 300 on the side opposite to the second electrode layer 200, and there is no contact between the fluid layer 400 and the second electrode layer 200. Please refer to [reference needed]. Figure 1 or Figure 3 .

[0048] When the friction layer 300 comes into contact with the second electrode layer 200, the surface of the friction layer 300 coincides with the surface of the second electrode layer 200; that is, they completely cover each other. Please refer to [reference needed]. Figure 2 .

[0049] Figure 4 The equivalent circuit model is used to represent the above-mentioned nanogenerator. Figure 5 This is the equivalent circuit model of a conventional triboelectric nanogenerator in existing technology. (Comparison) Figure 4 and Figure 5 Therefore, in the equivalent circuit model of the triboelectric nanogenerator provided in this application embodiment, the output current of the variable supercapacitor 700 is higher than the output current of the variable capacitor 800 in the equivalent circuit diagram of the prior art triboelectric nanogenerator.

[0050] In this embodiment, the amount of charge remaining on the surface of the friction layer 300 can be controlled by controlling the duration of the continuous flow of the fluid layer 400 on the friction layer 300 and the amount of charge in the fluid layer 400. This controls the amount of positive charge transfer when the friction layer 300 contacts the second electrode layer 200, thereby controlling the magnitude of the ion-driven current and thus controlling the magnitude of the DC current supplied to the device 500. Furthermore, this can also improve the durability and stability of the triboelectric generator.

[0051] The duration of the controlled fluid layer 400 flowing on the friction layer 300 corresponds to the relative motion frequency. Clearly, the lower the relative frequency, the longer the separation and contact time between the fluid layer 400 and the friction layer 300 in the triboelectric nanogenerator completes one cycle. Correspondingly, the longer the fluid layer 400 remains on the surface of the friction layer 300, the more charges the friction layer 300 can adsorb, thus achieving higher DC output. This triboelectric nanogenerator not only effectively solves the problem in existing technologies where increased current output with increasing motion frequency is difficult to utilize efficiently, or even difficult to utilize low-frequency or ultra-low-frequency energy, but also possesses a high DC output capability.

[0052] Furthermore, both the first electrode layer 100 and the second electrode layer 200 can be thin-film electrodes or obtained through printing technology. The friction layer 300 can also be a thin film of a corresponding material or obtained through printing technology, and the thickness of the fluid layer 400 can be controlled by adjusting the flow rate or the placement angle of the triboelectric nanogenerator. Based on this, the thickness of the aforementioned triboelectric nanogenerator can be reduced to below 3 mm, thereby effectively improving its flexibility.

[0053] Based on the same inventive concept, embodiments of this application also provide a flexible device, such as a flexible sensor, flexible electronic skin, etc., which includes the above-mentioned triboelectric nanogenerator.

[0054] In summary, the direct DC output generated by the aforementioned triboelectric nanogenerator avoids the current loss and increased size burden caused by the rectifier-to-DC conversion method in existing technologies. Furthermore, by replenishing the triboelectric layer with in-situ charge through the fluid layer, the device (especially the surface of the triboelectric layer) losses caused by triboelectric power generation in existing technologies are avoided.

[0055] In addition, the fluid layer flowing over the surface of the friction layer can effectively increase the dielectric constant of the internal capacitance of the triboelectric nanogenerator and reduce its internal resistance. According to P=I... 2 R, the above-mentioned triboelectric nanogenerator can avoid the loss of energy (i.e. current) through the triboelectric layer during the power generation process, thereby enhancing the energy output rate.

[0056] The following examples 1-4 provide a detailed description.

[0057] Example 1

[0058] The first motor layer and the second electrode layer are both carbon electrode sheets, the friction layer is a 100μm thick polytetrafluoroethylene film, and the fluid layer is deionized water. The maximum separation distance between the friction layer and the second electrode layer is 30mm.

[0059] Wind power is collected by wind-catching devices such as wind cups and wind turbines, or water flow energy is collected by devices such as water turbines. This energy is used to drive the relative movement between the friction layer and the second electrode layer, so that the friction layer and the second electrode layer move relative to each other at 1.0 Hz. That is, the time to complete one cycle of separation and contact is 1 second. This cycle is repeated to achieve the purpose of powering the device to be powered.

[0060] For the above triboelectric nanogenerator, a short-circuit current test was performed at a relative motion frequency of 1.0 Hz, and the resulting DC signal graph is shown below. Figure 6 As shown.

[0061] Example 2

[0062] Both the first motor layer and the second electrode layer are carbon electrode sheets. The friction layer is a 100μm thick polytetrafluoroethylene film, and the fluid layer is a high-humidity water vapor fluid layer formed by high-frequency (2000Hz) ultrasonic vibration of deionized water. The maximum separation distance between the friction layer and the second electrode layer is 30mm.

[0063] In this embodiment, the fluid layer is sprayed onto the surface of the friction layer. Wind power is collected by wind-catching devices such as wind cups and wind turbines, or water flow energy is collected by devices such as water turbines. This is used to drive the relative movement between the friction layer and the second electrode layer, so that the friction layer and the second electrode layer move relative to each other at 1.00 Hz. That is, the time to complete one cycle of separation and contact is 1 second. This cycle is repeated to achieve the purpose of powering the device to be powered.

[0064] For the above triboelectric nanogenerator, the short-circuit current was measured at a relative motion frequency of 1.0 Hz, and the DC signal graph is shown below. Figure 7 As shown.

[0065] Example 3

[0066] Both the first and second electrode layers are carbon electrode sheets. The friction layer is a 100μm thick polytetrafluoroethylene (PTFE) film, which is obtained by laser engraving with a power of 2W, improving the surface hydrophilicity of the PTFE film. The fluid layer is a deionized water stream. The maximum separation distance between the friction layer and the second electrode layer is 30mm.

[0067] Wind power is collected by wind-catching devices such as wind cups and wind turbines, or water flow energy is collected by devices such as water turbines. This energy is used to drive the friction layer and the second electrode layer to move relative to each other at 1.00 Hz. That is, the time to complete one cycle of separation and contact is 1 second. This cycle is repeated to achieve the purpose of powering the device to be powered.

[0068] For the above triboelectric nanogenerator, the short-circuit current was measured at a relative motion frequency of 1.0 Hz, and the DC signal graph is shown below. Figure 8 As shown.

[0069] Example 4

[0070] Both the first and second electrode layers are carbon electrode sheets. The friction layer is a 100μm thick polytetrafluoroethylene (PTFE) film, which is obtained by plasma sputtering at 50W for 10 seconds, improving the surface hydrophilicity of the PTFE film. The fluid layer is a stream of deionized water. The maximum separation distance between the friction layer and the second electrode layer is 30mm, and the motion frequency is [missing information].

[0071] Wind power is collected by wind-catching devices such as wind cups and wind turbines, or water flow energy is collected by devices such as water turbines. This energy is used to drive the relative movement between the friction layer and the second electrode layer, so that the friction layer and the second electrode layer move relative to each other at 1.0 Hz. That is, the time to complete one cycle of separation and contact is 1 second. This cycle is repeated to achieve the purpose of powering the device to be powered.

[0072] The short-circuit current of the above-mentioned triboelectric nanogenerator was measured at a relative motion frequency of 1.0 Hz, and the DC signal graph is shown below. Figure 9 As shown. The DC signal diagram obtained was obtained when the relative motion frequency was 10.0 Hz. Figure 10 As shown.

[0073] Combination Figures 6-10 It is understood that the triboelectric nanogenerator provided in this application generates current in a direction that always flows from the second electrode through the external circuit to the first electrode during contact and separation, i.e., it always maintains a short-circuit current in the same direction, thereby generating a current such as... Figure 6-10 The direct current shown.

[0074] Further by Figure 9 As can be seen, in Example 4, the triboelectric nanogenerator with an area of ​​only 1 square centimeter can generate a short-circuit current of more than 20 μA at 1.0 Hz, which is much higher than the power density of ordinary triboelectric nanogenerators in the prior art.

[0075] Continue to refer to Figure 10 Therefore, in the embodiments of this application, the triboelectric nanogenerator can still output direct current when the relative motion frequency is 10Hz.

[0076] Further comparison Figure 9 and Figure 10 As the frequency decreases, the positive charge accumulated on the friction layer continuously increases, which further improves the output performance of the triboelectric nanogenerator provided in this application. That is, the output current of the triboelectric nanogenerator in the embodiments of this application increases with decreasing frequency, thereby achieving the purpose of fully utilizing low-frequency and ultra-low-frequency energy and using low-frequency or ultra-low-frequency energy to complete high-energy current output.

[0077] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A triboelectric nanogenerator, characterized in that, include: A first electrode layer, a second electrode layer, and a friction layer; wherein the friction layer is disposed between the first electrode layer and the second electrode layer, and the friction layer is attached to the surface of the first electrode layer, and a fluid layer flows through one side of the friction layer opposite to the second electrode layer; When the second electrode layer separates from the friction layer, after the fluid layer flows through the friction layer, the surface of the friction layer is enriched with layered positive charges and layered negative charges to form a built-in electric field between the friction layer and the fluid layer. When the second electrode layer comes into contact with the friction layer, the built-in electric field is disrupted and an ion-driven current is formed to drive a directional current between the second electrode layer and the first electrode layer.

2. The triboelectric nanogenerator as described in claim 1, characterized in that, The friction layer and the second electrode layer are staggered, so that the fluid layer completely covers the side surface of the friction layer opposite to the second electrode layer.

3. The triboelectric nanogenerator as described in claim 1 or 2, characterized in that, The thickness of the friction layer is no greater than 1 mm.

4. The triboelectric nanogenerator as described in claim 3, characterized in that, The materials of the first electrode layer and the second electrode layer are each independently selected from at least one of the following: alloy conductive materials, composite metal materials, carbon materials, and organic conductive materials.

5. The triboelectric nanogenerator as described in claim 3, characterized in that, The material of the friction layer is selected from at least one of the following: polytetrafluoroethylene, fluororubber, polyvinylidene fluoride, polyimide, polyethylene, polystyrene, polyurethane rubber, cellulose, polypropylene, cis-1,4-polyisoprene, synthetic fiber, polymethyl methacrylate, polyvinylidene fluoride, or perfluoroethylene-propylene copolymer.

6. The triboelectric nanogenerator as described in claim 3, characterized in that, The fluid layer is selected from at least one of the following: deionized water, charged deionized water, lithium chloride aqueous solution, hydrogen chloride aqueous solution, lithium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium chloride aqueous solution, and organic solution.

7. The triboelectric nanogenerator as described in claim 3, characterized in that, The friction layer has a hydrophilic surface on one side relative to the second electrode layer. Preferably, the surface of the friction layer relative to the second electrode layer is a hydrophilic surface obtained by plasma sputtering and / or laser engraving.

8. The triboelectric nanogenerator as described in claim 3, characterized in that, The fluid layer is subjected to ultrasonic vibration at a frequency of not less than 500 Hz, which increases the positive charge content in the fluid layer.

9. A method for generating electricity based on the triboelectric nanogenerator according to any one of claims 1-8, characterized in that, include: The frequency of relative motion between the triboelectric nanogenerator's triboelectric layer and the second electrode layer is kept no greater than 10 Hz to output direct current; wherein, The frequency of relative motion refers to the frequency at which the friction layer and the second electrode layer periodically contact and separate; when the friction layer separates from the second electrode layer, the fluid layer flows on the surface of the friction layer on the side opposite to the second electrode layer, and there is no contact between the fluid layer and the second electrode layer; when the friction layer contacts the second electrode layer, the surface of the friction layer coincides with the surface of the second electrode layer.

10. A flexible sensor, characterized in that, include: The triboelectric nanogenerator according to any one of claims 1-8.

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