A multi-layer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator structure

Abstract

This invention provides a multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator structure, comprising, from bottom to top: a first electrode layer, a polarization-enhancing dielectric layer, a triboelectric layer, a second electrode layer, and a surface nanoparticle modification layer. Both the first and second electrode layers are made of copper foil and are used to collect charges generated by electrostatic induction. The polarization-enhancing dielectric layer is a PVDF thin film, used to enhance the interfacial charge storage capacity and electric field coupling strength, thereby enhancing the electrostatic induction effect and significantly improving the device's output voltage and current. The triboelectric layer is a FEP thin film, which can acquire electrons upon contact with the droplet. The surface nanoparticle modification layer is composed of PTFE nanoparticles, which adhere to the FEP thin film, further increasing the surface triboelectric charge density and thus improving the output voltage. This invention, through liquid-solid contact electrification and electrostatic induction mechanisms, can efficiently convert the mechanical energy of rainwater into electrical energy to provide power for low-power sensors in rainfall detection.

Description

Technical Field

[0001] This invention relates to the field of triboelectric nanogenerator technology, specifically to a liquid-solid triboelectric nanogenerator structure based on the liquid-solid contact electrification effect and its micro-energy harvesting device. Background Technology

[0002] Triboelectric nanogenerators (TENGs) are a novel energy conversion technology based on the triboelectric effect and electrostatic induction. This technology achieves the conversion of mechanical energy into electrical energy by generating charge transfer during the contact and separation of two different materials, creating a potential difference in an external circuit. Triboelectric nanogenerators offer advantages such as simple structure, a wide range of material choices, low cost, and good response to low-frequency mechanical energy, thus showing broad application prospects in fields such as micro-energy harvesting, self-powered sensors, and environmental energy utilization.

[0003] Depending on the form of the friction interface, triboelectric nanogenerators can be classified into several types, including solid-solid contact, liquid-solid contact, and gas-solid contact. Among them, liquid-solid triboelectric nanogenerators generate charge transfer through the contact and separation of liquid and solid surfaces, effectively utilizing liquid mechanical energy resources widely available in nature, such as raindrops, water flow, and ocean waves. Compared with traditional solid-solid triboelectric nanogenerators, liquid-solid triboelectric nanogenerators have advantages such as strong adaptability to liquid flow, flexible contact methods, and rich application scenarios, and therefore have attracted widespread attention in recent years.

[0004] However, existing liquid-solid triboelectric nanogenerators still have certain shortcomings in practical applications. For example, the hydrophobicity of the friction surface in some structures is insufficient, leading to instability in the contact and separation process of the liquid on the surface, thus affecting the charge generation efficiency. At the same time, some friction layer materials have weak electronegativity, limiting their triboelectric charging ability and thus restricting the output performance of the device. In addition, some structures are complex in terms of electrode arrangement and friction layer design, increasing the difficulty and cost of fabrication.

[0005] Therefore, designing a liquid-solid triboelectric nanogenerator structure with simple structure, good triboelectric performance and excellent hydrophobic properties to improve the triboelectric efficiency of the liquid-solid interface and enhance the charge output capability is of great significance for improving the practical application performance of liquid-solid triboelectric nanogenerators.

[0006] This invention constructs an improved liquid-solid triboelectric nanogenerator structure by introducing a polytetrafluoroethylene (PTFE) coating onto the surface of a fluorinated ethylene propylene copolymer (FEP) friction layer and combining it with a polyvinylidene fluoride (PVDF) dielectric layer and a copper electrode structure. This structure enhances the hydrophobicity and electronegativity of the friction surface, thereby strengthening the triboelectric effect at the liquid-solid interface and improving the device's output performance, while maintaining the advantages of simple structure and convenient fabrication process. Summary of the Invention

[0007] The purpose of this invention is to provide a multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator structure. Compared with ordinary liquid-solid contact separation triboelectric nanogenerators, this invention increases the triboelectric charge density at the liquid-solid interface and enhances the power output capability, thereby improving the practical application value of triboelectric nanogenerators in environmental energy harvesting.

[0008] Firstly, this paper provides a multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator, the overall structure of which, from bottom to top, includes: a first electrode layer, a polarization-enhancing dielectric layer, a triboelectric layer, a second electrode layer, and a surface nanoparticle modification layer. The first electrode layer is made of conductive copper foil (1); the polarization enhancement dielectric layer is a PVDF film (2) and is disposed above the first electrode layer; the triboelectric layer is an FEP film (3) and covers the upper surface of the polarization enhancement dielectric layer; the second electrode layer is a strip copper foil (4) and is disposed at 3 / 4 of the triboelectric layer; the surface nanoparticle modification layer is PTFE nanoparticles (5), which are made by diluting PTFE emulsion and dripping it onto the triboelectric layer while avoiding the second electrode layer.

[0009] The first electrode layer is a 5*5cm conductive copper foil (1). The copper foil (1) has high conductivity and is used to collect the induced charge generated by electrostatic induction and form an electron flow through an external circuit.

[0010] The polarization enhancement dielectric layer is a PVDF thin film (2) with a thickness of 30 μm, which is completely attached to the top of the first electrode layer. PVDF has strong molecular polarization characteristics and can form stable polarization under the action of an external electric field or triboelectric charge, thereby improving the electric field strength of the liquid-solid triboelectric nanogenerator.

[0011] The triboelectric layer is an FEP thin film (3) that is tightly bonded to the polarization-enhanced electrode layer. FEP is a strongly negatively charged material that easily gains electrons from water droplets when in contact with them, making the FEP surface negatively charged and able to retain electrons on the surface for a longer period of time.

[0012] The second electrode layer is a 50*2mm strip copper foil (4), located at 3 / 4 of the triboelectric layer, used to sense the change in electric field generated during the movement of the droplet, and to drive electrons to flow in the external circuit when a potential difference is generated between the first electrode layer and the second electrode layer.

[0013] The surface nanoparticle modification layer is made by diluting PTFE emulsion and drop-coating it onto the triboelectric layer. After the water evaporates, PTFE nanoparticles (5) are left on the surface of the FEP film (3). PTFE and FEP are both strongly negatively charged materials. The PTFE nanoparticles (5) attached to the FEP film (3) can increase the contact area with the droplets and further improve the surface triboelectric charge density.

[0014] The present invention has the following advantages and beneficial effects: One of the advantages of this invention is the addition of a high dielectric constant polarization dielectric layer. A PVDF film (2) is added between the first electrode layer and the tribological layer, which can enhance the storage capacity of interface charge and the electric field coupling strength, thereby increasing the charge density during friction and improving the output voltage. It can also serve as an insulating barrier to effectively prevent direct charge conduction between the first electrode layer and the tribological charging layer. The second advantage of this invention is that it uses a composite triboelectric layer formed by combining PTFE and FEP. FEP and PTFE are both strongly negatively charged materials. Attaching PTFE nanoparticles (5) to the FEP film (3) can effectively increase the contact area and enhance the negative charge of the friction surface. At the same time, it can promote the rapid sliding of droplets on the surface of the friction layer, thereby enhancing the electrostatic induction effect and improving the output performance and stability of the device. The third advantage of this invention is that the structure is simple to manufacture and the performance is significantly improved. Compared with the single-friction-layer contact-separated liquid-solid triboelectric nanogenerator, the multi-layer polarization-enhanced liquid-solid contact-separated triboelectric nanogenerator generates a larger induced voltage and is simple to manufacture. Attached Figure Description

[0015] Figure 1 A schematic diagram of the three-dimensional structure of a multi-layer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator; Figure 2 A cross-sectional view of the hierarchical structure of a multi-polarized enhanced liquid-solid contact separation triboelectric nanogenerator; Figure 3 The waveform of the induced voltage of a single droplet passing through a multi-layered polarization-enhanced liquid-solid contact separation triboelectric nanogenerator; Figure 4 A comparison of the output voltages of a conventional liquid-solid contact separation triboelectric nanogenerator and a multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator. Figure 5 A schematic diagram of the fabrication process for a multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator; Wherein: 1: copper foil, 2: PVDF film, 3: FEP film, 4: strip copper foil, 5: PTFE nanoparticles. Detailed Implementation

[0016] This paper presents a multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator, whose structure from bottom to top includes: a first electrode layer, a polarization-enhancing dielectric layer, a triboelectric layer, a second electrode layer, and a surface nanoparticle modification layer. The first electrode layer is a copper foil (1) with a thickness of 0.1 mm and adhesive backing. It is designed as a 5*5 cm square, and the first wire is led out from the adhesive backing. The polarization enhancement dielectric layer is a PVDF film (2) with a thickness of 30 μm and also has an adhesive backing. It is completely bonded to the copper foil (1) without obvious air bubbles. The triboelectric layer is an FEP film (3) with a thickness of 0.15 mm, and the FEP film (3) is tightly bonded to the PVDF film (2); The second electrode layer is a 50*2mm strip copper foil (4) with a thickness of 0.1mm, located at 3 / 4 of the FEP film (3), with a second wire leading out from its edge and connected to the first wire to form a closed loop in the external circuit; The surface nanoparticle modification layer is PTFE nanoparticles (5), each nanoparticle having a particle size between 0.22 μm and 0.25 μm. The preparation method is to dilute PTFE emulsion with 60% solid content with pure water at a ratio of 1:10 and then drop it onto the surface of FEP film (3), avoiding the strip copper foil (4). After the water evaporates, the entire multilayer polarization enhanced liquid-solid contact separation triboelectric nanogenerator is completed.

[0017] Working principle: This invention converts the mechanical energy of raindrops into electrical energy based on the triboelectric effect and electrostatic induction principle. A multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator is connected to an external circuit and tilted at 45 degrees. When a raindrop falls onto the composite triboelectric layer, it rubs against the FEP film (3) and PTFE nanoparticles (5). Due to the different electron affinity between the raindrop and the solid interface, electron transfer occurs, causing the FEP film (3) and PTFE nanoparticles (5) to gain electrons and become negatively charged, while the raindrop loses electrons and becomes positively charged.

[0018] As the droplet slides down the inclined surface under the influence of gravity and passes through the second electrode layer, the contact position between the droplet and the strip copper foil (4) changes continuously, causing a change in the surface charge distribution. At this time, the potential difference between the first and second electrode layers continues to change. Under the action of electrostatic induction, electrons are transferred, forming a significant voltage. When the contact area between the droplet and the strip copper foil (4) is at its maximum, the rate of change of the contact area is a huge positive variable, resulting in a voltage peak.

[0019] As the droplet gradually leaves the strip copper foil (4), the contact area gradually decreases. At this point, the rate of change of the contact area is negative and small, resulting in a small negative voltage value. When the droplet completely leaves the strip copper foil (4) and the composite friction layer, electron movement stops.

[0020] Specifically, Figure 1 This is a three-dimensional structural schematic diagram of the multi-layer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator provided by the present invention, which shows the overall shape of the multi-layer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator. Figure 2 A cross-sectional view of the hierarchical structure of the multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator provided by the present invention. Figure 3 The voltage waveform of a single droplet passing through a multi-layered polarization-enhanced liquid-solid contact separation triboelectric nanogenerator is shown. Figure 4 The output voltage comparison diagram of the liquid-solid contact separation triboelectric nanogenerator and the multilayer polarization enhanced liquid-solid contact separation triboelectric nanogenerator shows the help of PVDF film (2) and PTFE nanoparticles (5) in improving the performance of the liquid-solid triboelectric nanogenerator.

[0021] Based on the above embodiments, this invention provides a method for preparing a multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator, wherein... Figure 5 The flowchart illustrating the fabrication method of the multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator of the present invention specifically includes: S1, cut a 50*50mm square copper foil from the copper foil roll as the first electrode layer.

[0022] S2, PVDF film is bonded to the adhesive backing of the copper foil.

[0023] S3, tightly bond the FEP film onto the PVDF film, and cut out a 50*2mm strip of copper foil and attach it to 3 / 4 of the FEP film.

[0024] S4. Dilute the PTFE emulsion and drop it onto the FEP film without contacting the strip copper foil.

[0025] It should be noted that the above-mentioned technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of the present invention specification; and those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims of the present invention.

Claims

1. A multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator structure, characterized by... From bottom to top, it includes: a first electrode layer, a polarization enhancement dielectric layer, a triboelectric layer, a second electrode layer, and a surface nanoparticle modification layer; The multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator structure has a first electrode layer of 50*50mm copper foil, on which a polarization-enhancing dielectric layer PVDF film is tightly bonded. An FEP film, as a triboelectric layer, is bonded to the PVDF film. The second electrode layer, a strip copper foil, and the surface nanoparticle modification layer, PTFE nanoparticles, are both located on the FEP film. The PTFE nanoparticles are only attached to the FEP film and do not contact the strip copper foil. When a droplet falls onto a multi-layered polarization-enhanced liquid-solid contact separation triboelectric nanogenerator tilted at 45 degrees, the triboelectric layer and the surface nanoparticle modification layer absorb electrons from the droplet, becoming negatively charged, while the droplet loses electrons and becomes positively charged. As the contact area between the droplet and the second electrode layer changes, an induced voltage is generated, producing a positive peak value momentarily before dropping to a negative value and then returning to its original value. The polarization-enhanced dielectric layer and the surface nanoparticle modification layer can enhance the interfacial charge storage capacity and electric field coupling strength, and further improve the surface triboelectric charge density, thereby increasing the output voltage.

2. The multi-layer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator according to claim 1, characterized in that, The PTFE nanoparticles do not completely cover the FEP film. The PTFE nanoparticles are made by diluting a PTFE emulsion with a solid content of 60% with pure water at a ratio of 1:10 and then drop-coating it onto the surface of the FEP film. Each nanoparticle has a particle size between 0.22 μm and 0.25 μm.

3. The multilayer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator according to claim 1, characterized in that, The second electrode layer is a strip of copper foil with a size of 50*2mm, attached to 3 / 4 of the FEP film, and not in contact with PTFE nanoparticles.

4. The multi-layer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator according to claim 1, characterized in that, The PVDF film serves as a polarization enhancement medium layer between the FEP film and the first electrode layer, thereby enhancing the interface charge storage capacity and electric field coupling strength.

5. The multi-layer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator according to claim 1, characterized in that, The first electrode layer is a 50*50mm copper foil, which is used as the bottom electrode.

6. The multi-layer polarization-enhanced liquid-solid contact separation triboelectric nanogenerator according to claim 1, characterized in that, The triboelectric nanogenerator is tilted at a fixed angle, allowing droplets to slide directionally along the surface of the triboelectric nanogenerator under the influence of gravity, and sequentially contact and detach from the strip copper foil.

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