Bidirectional response type nano friction generator and preparation method thereof

Abstract

The invention belongs to the technical field of micro-nano energy, and discloses a bidirectional response type nano friction generator and a preparation method thereof. The surface of a TPU / PEG / GO film is coated with a solution A containing TPU / PEG and a curing agent, and a TPU-PEG / TPU-PEG-GO composite film is prepared through curing and cooling and serves as a positive electrode; the PVDF / BaTiO3 fiber membrane is used as a negative electrode, and the PVDF / BaTiO3 composite material is prepared by assembling. The positive electrode material of the nanometer friction generator has bidirectional response shape memory performance at a certain temperature, and the positive electrode and the negative electrode are automatically contacted and separated through external photo-thermal stimulation so as to carry out electric energy conversion. The friction nanometer generator is ensured to still provide stable power output even in a deformation state of bending or stretching and the like, and the requirements of equipment with different shapes, sizes and flexibility requirements can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano energy, and particularly to a preparation method for materials applicable to the technical field of micro-nano energy. Background Art

[0002] With the rapid development of modern society, the demand for energy is increasing day by day. The limited nature of traditional energy and the environmental problems brought about during its use have prompted people to seek clean and sustainable new energy sources. There are still many technical problems with traditional triboelectric generators. For example: ① Low energy conversion efficiency: In the design of traditional triboelectric generators, the selection of electrode materials is often limited to common metals or simple polymers. For example, although metal electrodes such as aluminum and copper have good electrical conductivity, they have limitations in the interfacial interaction with the friction layer and the storage and transmission of charges, resulting in low charge generation and collection efficiency. The overall energy conversion efficiency is difficult to break through the bottleneck and cannot meet the continuous operation requirements of some small self-powered devices with high energy demands. ② Insufficient stability of electrode materials: In many existing triboelectric generator electrodes, during long-term friction, due to mechanical wear, chemical corrosion, and the influence of environmental factors (such as humidity and temperature changes), the electrode surface is prone to damage, oxidation, etc., causing the electrical properties of the electrodes to gradually decline, thereby affecting the output performance stability and service life of the triboelectric generator. As a technology that can collect scattered mechanical energy in the environment and convert it into electrical energy, the nanogenerator conforms to the trend of sustainable energy development and provides an innovative idea for solving energy problems. The continuous progress of nanoscience and technology provides a basis for the research and development of nanogenerators. People have a deeper understanding of the properties and preparation methods of nanomaterials and can design and synthesize nanomaterials with specific structures and properties for constructing high-performance triboelectric nanogenerators.

[0003] Traditional nanogenerators often only respond to a single type of external stimulus, such as pure pressure or friction, resulting in relatively single functions. The performance of nanogenerators may be greatly affected by environmental factors, such as temperature, humidity, dust, etc. Under different environmental conditions, their output performance may fluctuate greatly, limiting their application in some extreme environments or complex working conditions. The energy collection efficiency of traditional nanogenerators is limited in some cases. Although nanogenerators have made progress in collecting mechanical energy and converting it into electrical energy, there is still room for improvement in the overall energy conversion efficiency. In practical applications, due to factors such as energy loss during the friction process and charge transfer efficiency, the final electrical energy output is different from the theoretical value. Summary of the Invention

[0004] To address the limitations of the single response of traditional tribogenerators, as well as the technical problems of low environmental adaptability and low energy harvesting efficiency, the present invention proposes a dual-response nanogenerator and its preparation method. By integrating the dual response mechanisms of mechanical energy and thermal energy, and combining the enhanced electret effect and the environmental self-adaptive characteristics of shape memory materials, the energy harvesting efficiency and environmental adaptability are significantly improved. Through optimizing the electret material and surface micro-nano structure design, the generator has efficient charge storage and migration capabilities. At the same time, through the shape memory characteristics of the flexible substrate, long-term stable operation and self-recovery performance in complex environments are achieved, providing new ideas for the development of multifunctional self-powered devices. The energy management circuit of traditional tribogenerators is not efficient enough to effectively convert the harvested energy into usable electrical energy, and its output power and voltage are relatively low. For example, the open-circuit voltage and power density of traditional contact-separation tribogenerators are low, while the open-circuit voltage of the optimized new tribogenerator can reach 205V, much higher than the traditional structure, such as Figure 3 . The low energy harvesting efficiency of traditional triboelectric nanogenerators (TENGs) is mainly due to their relatively low output performance. Specifically, the triboelectricity of triboelectric materials is weak, resulting in low charge transfer and accumulation efficiency; the friction layer structure design is unreasonable, affecting the migration and storage of charges; the device structure is simple and cannot make full use of mechanical energy. In addition, the external charge injection technology has high requirements and high costs, and the injected charges are easy to dissipate, affecting the output stability and durability of TENGs. These factors together lead to the problem of low energy harvesting efficiency of traditional TENGs.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: A preparation method of a dual-response nanogenerator, the steps are as follows: (1) Dissolve TPU in a solvent, add PEG1000 and a curing agent in sequence and dissolve them, and obtain solution A after heating and standing; (2) Add graphene oxide to solution A to obtain solution B. After heating and standing, coating and curing, a TPU / PEG / GO film is obtained; coat solution A on the surface of the TPU / PEG / GO film, and obtain a dual-shape memory material, that is, a TPU-PEG / TPU-PEG-GO composite film after curing and cooling; among them, TPU-PEG in the TPU-PEG / TPU-PEG-GO composite film is used as the passive layer of the dual-shape memory material, and the TPU / PEG / GO film is used as the active layer of the dual-shape memory material; first coat solution A on the surface of the TPU / PEG / GO film, then put it into an oven to cure it, and put it into a hot press after curing to hot press it evenly.

[0006] (3) Dissolve BaTiO3 nanoparticles in the PVDF solution and prepare a PVDF / BaTiO3 fiber membrane by electrospinning; among them, the diameter of the fibers in the PVDF / BaTiO3 fiber membrane is 1-2 μm.

[0007] (4) Use the TPU-PEG / TPU-PEG-GO composite membrane as the positive electrode and the PVDF / BaTiO3 fiber membrane as the negative electrode to assemble a dual-responsive nanogenerator.

[0008] In the above step (1), the addition amount of PEG 1000 is 10-40% of the mass of TPU, and the mass ratio of TPU to the curing agent is 5: (1-2).

[0009] In the above step (1), 0.6-0.7 g of TPU is added to each gram of the solvent.

[0010] In the above step (2), the graphene oxide in solution B is 1%-5% of the mass of TPU.

[0011] In the above step (2), the thickness of TPU-PEG in the TPU-PEG / TPU-PEG-GO composite membrane is 0.3-0.5 cm.

[0012] Furthermore, in step (1), the solvent is N,N-dimethylformamide or tetrahydrofuran.

[0013] Furthermore, in step (1), the curing agent is 4,4'-diaminodiphenyl sulfone (DDS); the curing is to raise the temperature from room temperature to 60-100 °C and cure for 2-4 h.

[0014] In the above step (3), the content of PVDF in the PVDF solution is 12 wt%; the solvent is N,N-dimethylformamide, tetrahydrofuran.

[0015] In the above step (3), the mass ratio of BaTiO3 nanoparticles to PVDF is 0.1-0.7:1.

[0016] In the above step (3), the process parameters of electrospinning are: the applied voltage is 15-20 kV, the injection speed is 11-22 mL / min, the receiving distance is 13-20 cm, the receiver rotation speed is 1600 r.p.m, the chamber temperature is controlled at 33-50 °C, and the spinning current is 2-5 mA.

[0017] A dual-responsive nanogenerator prepared by the above preparation method.

[0018] The beneficial effects produced by the present invention are: (1) The nano triboelectric generator of the present invention can convert the alternating current (AC) generated in both the forward and reverse directions into direct current (DC). The bi-directional responsive shape memory material can automatically adjust its shape in response to photothermal stimuli at a specific temperature, realizing the automatic contact and separation of the positive and negative electrodes, thereby controlling the generation and transmission of electric energy. This material not only responds to forward stimuli but also to reverse stimuli, ensuring that the generation and transmission of electric energy can be carried out efficiently in both directions, enabling the generator to maintain a stable electric energy output under different mechanical motion states. With the shape memory property of the material, the positive and negative electrodes are dynamically adjusted during the contact and separation process, and thus a stable electric energy output can be generated during both the forward and reverse processes of mechanical motion. Therefore, this nano triboelectric generator can directly convert the alternating current (AC) generated in both the forward and reverse directions into direct current (DC) output without a bridge rectifier, significantly improving the efficiency and flexibility of energy collection and conversion. Moreover, the positive electrode composite film has bi-directional responsive shape memory performance in an environment at a certain temperature, so the bi-directional responsive shape memory property of the positive electrode material can be utilized to make the positive and negative electrodes automatically contact and separate through external photothermal stimuli for electric energy conversion. This ensures that the triboelectric nanogenerator can still provide a stable power output even in a deformed state such as bending or stretching.

[0019] (2) The present invention utilizes the bi-directional responsive property of the positive electrode material to achieve automatic contact and separation power generation of the positive and negative electrodes through photothermal stimuli. Electrospinning is used to prepare PVDF / BaTiO3 nanofibers with a diameter of 1 - 2 μm to optimize charge transfer. The components of TPU / PEG / GO are precisely regulated, and 0.2% BaTiO3 is evenly dispersed in PVDF to increase the dielectric constant, realizing the AC-to-DC output without a bridge rectifier, and it can instantaneously light up 50 LED bulbs, as Figure 4 . At the same time, the ratio is precisely controlled (the ratio of TPU to PEG is 100:10, and the ratio of the curing agent to TPU is 100:20), and 0.2% BaTiO3 is added to PVDF through stirring and ultrasonic treatment to obtain a stable composite material; when preparing the TPU / PEG / GO composite film, it is cured at 60 °C for 2 hours to enhance its adhesion and durability to the substrate film; and the photothermal response of the positive electrode is utilized to make the positive and negative electrodes automatically contact and separate, solving the problem of unstable electrode materials.

[0020] (3) Compared with traditional power sources, the novel bi-directional responsive nano triboelectric generator shows great advantages in terms of weight, volume, personal safety, material diversity, and environmental friendliness, and it is convenient to prepare triboelectric nanogenerators of various structures and forms, which can meet the device requirements of different shapes, sizes, and flexibility requirements. Description of the Drawings

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 It is the SEM image of PVDF / BaTiO3 fiber.

[0023] Figure 2 It is the test chart of the electrical performance of the triboelectric nanogenerator prepared by the present invention. Among them, (a) is the schematic diagram of the performance test process; (b) is the simple measurement chart of the performance of the triboelectric nanogenerator with a multimeter.

[0024] Figure 3 It is the test result chart of the output electrical signal of the generator prepared in Example 1. Among them, (a) is the current I-t chart; (b) is the voltage V-t chart.

[0025] Figure 4 It is the test result of the TENG lighting an LED small light bulb. Specific embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0027] Example 1 The preparation method of the bidirectional response type triboelectric nanogenerator in this embodiment is as follows: (1) Prepare a TPU / PEG solution (solution A) a. Weigh 5 g of TPU and add 7.5 g of N,N-dimethylformamide solvent into a beaker with a magnetic rotor, and heat and stir on a constant temperature magnetic stirrer at a rotation speed of 100 r / min and 30 °C to obtain a TPU solution.

[0028] b. Add 10% of the weight of PEG1000 based on the weight of TPU to the TPU solution obtained in step a, and stir evenly to obtain a PU / PEG solution.

[0029] c. Add the curing agent - 4,4'-diaminodiphenyl sulfone (DDS, the weight ratio of TPU to the curing agent is 100:20) to the PU / PEG solution obtained in step b, stir evenly, and then continue to heat and stand to obtain solution A.

[0030] (2) Preparation of TPU-PEG / TPU-PEG-GO composite film a. Prepare solution A according to the preparation method in step (1), add 0.15 g of graphene oxide under the condition of heating at 30 °C, stir evenly and then continue heating and standing. After 5 min, lay the film on a PET release film and place it in an electrothermal constant temperature blast drying oven for curing. Among them, the curing temperature gradually rises from room temperature to 60 °C, take it out after 2 h, and obtain the TPU / PEG / GO film.

[0031] b. Coat solution A on the strip of TPU / PEG / GO to obtain a composite film. Place the composite film in an oven and gradually heat it to 60 °C. After 2 h of curing, remove the composite film from the PET release film; place it at room temperature for cooling. After cooling, the film material bends to obtain a solid composite film, that is, the TPU-PEG / TPU-PEG-GO composite film.

[0032] (3) Preparation of PVDF / BaTiO3 fiber membrane Add BaTiO3 nanoparticles (0.1 g) to the prepared 5 g of PVDF solution with a PVDF mass fraction of 12 wt% (the solvent is N,N-dimethylformamide), stir for 4 h, and then ultrasonically treat for 2 h. And at a rotation speed of 100 r / min and 45 °C, stir the PVDF / BaTiO3 solution for half an hour to obtain a spinning solution. The spinning solution is electrospun under the conditions of an applied voltage of 15 kV, a spinning distance of 13 cm, a drum collector (receiver) set at 1600 r.p.m, a flow rate of 11 mL / min, a chamber temperature of 33 °C, and an electrospinning current of 2 mA. After electrospinning for 2 h, the PVDF / BaTiO3 fiber membrane is prepared. Figure 1 Figure

[0033] Assembly of bidirectional response type nanogenerator Using the TPU-PEG / TPU-PEG-GO composite film as the positive electrode, the PVDF / BaTiO3 fiber membrane as the negative electrode, and copper tape as the positive and negative friction layer parts, stick both the TPU-PEG / TPU-PEG-GO composite film and the PVDF / BaTiO3 fiber membrane on an elastic PI board, and then fold the PI board in half (as Figure 2As shown in Figure b), the TPU-PEG / TPU-PEG-GO composite film and the PVDF / BaTiO3 fiber film are placed on both sides, enabling contact separation. When an external mechanical force acts on the elastic PI plastic plate to press the upper and lower fiber films, the two films come into contact and friction with each other; when the external mechanical force is withdrawn, the upper and lower fiber films bounce off under the self-recovery and rebound of the PI plate, causing the two films to be in a separated state. A copper foil is led out on the back of the double-conductive copper tape as an electrode wire to connect the test system and the low-power load, and finally a triboelectric nanogenerator is assembled and fabricated.

[0034] Example 2 The preparation method of the bidirectional response type triboelectric nanogenerator in this example is as follows: (1) Prepare the TPU / PEG solution (Solution A) a. Weigh 6 g of TPU and add 9 g of N,N-dimethylformamide solvent into a beaker with a magnetic rotor, and heat and stir on a constant temperature magnetic stirrer at a rotation speed of 200 r / min and a temperature of 40 °C to obtain the TPU solution.

[0035] b. Add PEG 1000 accounting for 20% of the weight of TPU to the TPU solution obtained in step a, and stir evenly to obtain the PU / PEG solution.

[0036] c. Add the curing agent - 4,4'-diaminodiphenylsulfone (DDS, the weight ratio of TPU to the curing agent is 100:30) to the PU / PEG solution obtained in step b, stir evenly, and then continue to heat and let stand to obtain Solution A.

[0037] (2) Prepare the TPU-PEG / TPU-PEG-GO composite film a. Prepare Solution A according to the preparation method in step (1), add 0.18 g of graphene oxide under the condition of heating at 40 °C, stir evenly, and then continue to heat and let stand. After 5 min, spread the film on the PET release film and place it in an electrothermal constant temperature blast drying oven for curing. Among them, the curing temperature gradually rises from room temperature to 70 °C, and it is taken out after 2 h to obtain the TPU / PEG / GO film.

[0038] b. Coat Solution A on the strip of TPU / PEG / GO to obtain a composite film. Place the composite film in an oven and gradually heat it to 70 °C. After 2 h of curing, remove the composite film from the PET release film; let it cool at room temperature. After cooling, the film material bends to obtain a solid composite film, that is, the TPU-PEG / TPU-PEG-GO composite film.

[0039] (3) Preparation of the PVDF / BaTiO3 fiber film 0.2 g of BaTiO3 nanoparticles were added to 5 g of the prepared PVDF solution with a PVDF mass fraction of 12 wt% (the solvent was N,N-dimethylformamide), and the mixture was stirred for 4 h and then ultrasonicated for 2.5 h. Then, at a rotation speed of 200 r / min and 55 °C, the PVDF / BaTiO3 solution was stirred for half an hour to obtain a spinning solution. The spinning solution was electrospun under the conditions of an applied voltage of 16 kV, a spinning distance of 15 cm, a drum collector (receiver) set at 1600 r.p.m, a flow rate of 15 mL / min, a chamber temperature of 35 °C, and an electrospinning current of 2.5 mA. After electrospinning for 2 h, a PVDF / BaTiO3 fiber membrane was prepared.

[0040] Assembly of a Bidirectional Responsive Nanogenerator Using the TPU-PEG / TPU-PEG-GO composite membrane as the positive electrode and the PVDF / BaTiO3 fiber membrane as the negative electrode, and using copper tape as the friction layer part of the positive and negative electrodes, both the TPU-PEG / TPU-PEG-GO composite membrane and the PVDF / BaTiO3 fiber membrane were adhered to the elastic PI plate. Then, the PI plate was folded in half so that the TPU-PEG / TPU-PEG-GO composite membrane and the PVDF / BaTiO3 fiber membrane were on both sides, enabling contact separation. When an external mechanical force acts on the elastic PI plastic plate to press the upper and lower fiber membranes to promote contact friction between the two membranes; when the external mechanical force is withdrawn, the upper and lower fiber membranes bounce off under the self-recovery and rebound of the PI plate, causing the two membranes to be in a separated state. A copper foil was led out from the back of the double-conductive copper tape as an electrode wire to connect the test system and the low-power load, and finally, a triboelectric nanogenerator was assembled.

[0041] Example 3 The preparation method of the bidirectional responsive nanogenerator in this example is as follows: (1) Prepare the TPU / PEG solution (Solution A) a. Weigh 8 g of TPU and add 12 g of N,N-dimethylformamide solvent to a beaker with a magnetic rotor. Heat and stir on a constant temperature magnetic stirrer at a rotation speed of 300 r / min and 50 °C to obtain a TPU solution.

[0042] b. Add PEG1000 accounting for 30% of the weight of TPU to the TPU solution obtained in step a and stir evenly to obtain a PU / PEG solution.

[0043] c. Add the curing agent - 4,4'-diaminodiphenyl sulfone (DDS, the weight ratio of TPU to the curing agent is 100:35) to the PU / PEG solution obtained in step b, stir evenly, and then continue to heat and let stand to obtain Solution A.

[0044] (2) Preparation of TPU-PEG / TPU-PEG-GO composite membrane a. Prepare solution A according to the preparation method in step (1), add 0.24 g of graphene oxide under the condition of heating at 40 °C, stir evenly and then continue to heat and stand. After 8 min, spread the membrane on a PET release film and place it in an electrothermal constant temperature blast drying oven for curing. Among them, the curing temperature gradually rises from room temperature to 80 °C, and it is taken out after 3.5 h to obtain the TPU / PEG / GO membrane.

[0045] b. Coat solution A on the strip of TPU / PEG / GO to obtain a composite membrane. Place the composite membrane in an oven and gradually heat it to 80 °C. After 3.5 h of curing is completed, remove the composite membrane from the PET release film; place it at room temperature for cooling. After cooling, the membrane material bends to obtain a solid composite membrane, that is, the TPU-PEG / TPU-PEG-GO composite membrane.

[0046] (3) Preparation of PVDF / BaTiO3 fiber membrane Add BaTiO3 nanoparticles (0.3 g) to the prepared 5 g of PVDF solution with a PVDF mass fraction of 12 wt% (the solvent is N,N-dimethylformamide), stir for 4.5 h, and then ultrasonically treat for 2.5 h. And at a rotation speed of 300 r / min and 50 °C, stir the PVDF / BaTiO3 solution for half an hour to obtain a spinning solution. The spinning solution is electrospun under the conditions of an applied voltage of 18 kV, a spinning distance of 18 cm, a drum collector (receiver) set at 1600 r.p.m, a flow rate of 11 mL / min, a chamber temperature of 40 °C, and an electrospinning current of 3 mA. After electrospinning for 2 h, the PVDF / BaTiO3 fiber membrane is prepared.

[0047] (4) Assembly of a bi-directional responsive nanogenerator Using the TPU-PEG / TPU-PEG-GO composite membrane as the positive electrode and the PVDF / BaTiO3 fiber membrane as the negative electrode, and using copper tape as the friction layer part of the positive and negative electrodes, stick both the TPU-PEG / TPU-PEG-GO composite membrane and the PVDF / BaTiO3 fiber membrane on an elastic PI plate, and then fold the PI plate in half so that the TPU-PEG / TPU-PEG-GO composite membrane and the PVDF / BaTiO3 fiber membrane are on both sides, so that contact separation can be carried out. When an external mechanical force acts on the elastic PI plastic plate to press the upper and lower fiber membranes to promote mutual contact and friction between the two membranes; and when the external mechanical force is withdrawn, the upper and lower fiber membranes bounce off under the self-recovery and rebound action of the PI plate, so that the two layers of membranes are in a separated state. A copper foil is led out on the back of the double-conductive copper tape as an electrode wire to connect to the test system and a low-power load, and finally a triboelectric nanogenerator is assembled.

[0048] Example 4 The preparation method of the two-way response type nanogenerator in this example is as follows: (1) Prepare the TPU / PEG solution (solution A) a. Weigh 10 g of TPU and add 15 g of N,N-dimethylformamide solvent into a beaker with a magnetic rotor. Heat and stir on a constant temperature magnetic stirrer at a speed of 350 r / min and 60 °C to obtain the TPU solution.

[0049] b. Add PEG1000 accounting for 40% of the weight of TPU into the TPU solution obtained in step a, and stir evenly to obtain the PU / PEG solution.

[0050] c. Add the curing agent - 4,4'-diaminodiphenylsulfone (DDS, the weight ratio of TPU to the curing agent is 100:40) into the PU / PEG solution obtained in step b, stir evenly, and then continue to heat and stand to obtain solution A.

[0051] (2) Prepare the TPU-PEG / TPU-PEG-GO composite film a. Prepare solution A according to the preparation method in step (1), add 0.3 g of graphene oxide under the condition of heating at 40 °C, stir evenly, and then continue to heat and stand. After 10 min, spread the film on a PET release film and place it in an electrothermal constant temperature forced air drying oven for curing. Among them, the curing temperature gradually rises from room temperature to 100 °C, and take it out after 4 h to obtain the TPU / PEG / GO film.

[0052] b. Coat solution A on the strip of TPU / PEG / GO to obtain a composite film. Place the composite film in an oven and gradually heat it to 100 °C. After 4 h of curing, remove the composite film from the PET release film; place it at room temperature for cooling. After cooling, the film material bends to obtain a solid composite film, that is, the TPU-PEG / TPU-PEG-GO composite film.

[0053] (3) Preparation of the PVDF / BaTiO3 fiber membrane 0.4 g of BaTiO3 nanoparticles were added to 5 g of the prepared PVDF solution with a PVDF mass fraction of 12 wt% (the solvent was N,N-dimethylformamide), and the mixture was stirred for 5 h and then ultrasonically treated for 3 h. Then, at a rotation speed of 350 r / min and 60 °C, the PVDF / BaTiO3 solution was stirred for half an hour to obtain a spinning solution. The spinning solution was electrospun under the conditions of an applied voltage of 20 kV, a spinning distance of 20 cm, a drum collector (receiver) set at 1600 r.p.m, a flow rate of 22 mL / min, a chamber temperature of 50 °C, and an electrospinning current of 5 mA. After electrospinning for 2 h, a PVDF / BaTiO3 fiber membrane was prepared.

[0054] (4)Assembly of the bidirectional response type nanogenerator Using the TPU-PEG / TPU-PEG-GO composite film as the positive electrode and the PVDF / BaTiO3 fiber membrane as the negative electrode, and using copper tape as the friction layer part of the positive and negative electrodes, both the TPU-PEG / TPU-PEG-GO composite film and the PVDF / BaTiO3 fiber membrane were adhered to the elastic PI plate. Then the PI plate was folded in half so that the TPU-PEG / TPU-PEG-GO composite film and the PVDF / BaTiO3 fiber membrane were on both sides, enabling contact separation. When an external mechanical force acts on the elastic PI plastic plate to press the upper and lower fiber membranes to make the two membranes contact and rub against each other; when the external mechanical force is withdrawn, the upper and lower fiber membranes bounce off under the self-recovery and rebound of the PI plate, causing the two membranes to be in a separated state. Copper foil was led out from the back of the double conductive copper tape as the electrode wire to connect the test system and the low-power load, and finally a triboelectric nanogenerator was assembled.

[0055] Example 5 The preparation method of the bidirectional response type nanogenerator in this example is as follows: (1)Prepare the TPU / PEG solution (Solution A) a. Weigh 5 g of TPU and add 7.5 g of N,N-dimethylformamide solvent to a beaker with a magnetic rotor, and heat and stir on a constant temperature magnetic stirrer at a rotation speed of 100 r / min and 30 °C to obtain a TPU solution.

[0056] b. Add 10% of the weight of TPU of PEG1000 to the TPU solution obtained in step a and stir evenly to obtain a PU / PEG solution.

[0057] c. Add the curing agent - 4,4'-diaminodiphenyl sulfone (DDS, the weight ratio of TPU to the curing agent is 100:20) to the PU / PEG solution obtained in step b, stir evenly and then continue to heat and let stand to obtain Solution A.

[0058] (2) Preparation of TPU-PEG / TPU-PEG-GO composite membrane a. Prepare solution A according to the preparation method in step (1), add 0.05 g of graphene oxide under the condition of heating at 30 °C, stir evenly and then continue to heat and stand. After 5 min, spread the film on the PET release film and place it in an electrothermal constant temperature blast drying oven for curing. Among them, the curing temperature gradually rises from room temperature to 60 °C, and it is taken out after 2 h to obtain the TPU / PEG / GO membrane.

[0059] b. Coat solution A on the strip of TPU / PEG / GO to obtain a composite membrane. Place the composite membrane in an oven and gradually heat it to 60 °C. After 2 h of curing, remove the composite membrane from the PET release film; place it at room temperature for cooling. After cooling, the membrane material bends to obtain a solid composite membrane, that is, the TPU-PEG / TPU-PEG-GO composite membrane.

[0060] (3) Preparation of PVDF / BaTiO3 fiber membrane Add BaTiO3 nanoparticles (0.1 g) to the prepared 5 g PVDF solution with a PVDF mass fraction of 12 wt% (the solvent is N,N-dimethylformamide), stir for 4 h, and then ultrasonically treat for 2 h. And at a rotation speed of 100 r / min and 45 °C, stir the PVDF / BaTiO3 solution for half an hour to obtain a spinning solution. The spinning solution is electrospun under the conditions of an applied voltage of 15 kV, a spinning distance of 13 cm, a drum collector (receiver) set at 1600 r.p.m, a flow rate of 11 mL / min, a chamber temperature of 33 °C, and an electrospinning current of 2 mA. After electrospinning for 2 h, the PVDF / BaTiO3 fiber membrane is prepared. Figure 1 is the SEM image of the PVDF / BaTiO3 fiber membrane. It can be seen from the figure that the surface of the nanofibers is uneven, and there are multiple protrusions on the surface of each nanofiber. This is caused by the doping of BaTiO3 electret particles. These protrusions are generally nanoscale in size, which further increases the specific surface area of the nanofiber surface. Therefore, it will also have a certain promoting effect on the output performance of the generator.

[0061] Assembly of the two-way responsive nanogenerator Using the TPU-PEG / TPU-PEG-GO composite membrane as the positive electrode, the PVDF / BaTiO3 fiber membrane as the negative electrode, and copper tape as the frictional layer part of the positive and negative electrodes, both the TPU-PEG / TPU-PEG-GO composite membrane and the PVDF / BaTiO3 fiber membrane are adhered to the elastic PI plate. Then the PI plate is folded in half so that the TPU-PEG / TPU-PEG-GO composite membrane and the PVDF / BaTiO3 fiber membrane are on both sides, enabling contact separation. When an external mechanical force acts on the elastic PI plastic plate to press the upper and lower fiber membranes to make them contact and rub against each other; when the external mechanical force is withdrawn, the upper and lower fiber membranes bounce off under the self-recovery and rebound of the PI plate, making the two membranes in a separated state. A copper foil is led out from the back of the double-conductive copper tape as an electrode wire to connect the test system and the low-power load, and finally a triboelectric nanogenerator is assembled and made.

[0062] Example 6 The preparation method of the bidirectional response type triboelectric nanogenerator in this example is as follows: (1) Prepare the TPU / PEG solution (solution A) a. Weigh 5 g of TPU and add 7.5 g of N,N-dimethylformamide solvent into a beaker with a magnetic rotor, and heat and stir on a constant temperature magnetic stirrer at a rotation speed of 100 r / min and 30 °C to obtain the TPU solution.

[0063] b. Add PEG1000 accounting for 10% of the weight of TPU into the TPU solution obtained in step a, and stir evenly to obtain the PU / PEG solution.

[0064] c. Add the curing agent - 4,4'-diaminodiphenyl sulfone (DDS, the weight ratio of TPU to the curing agent is 100:20) into the PU / PEG solution obtained in step b, stir evenly, and then continue to heat and let stand to obtain solution A.

[0065] (2) Prepare the TPU-PEG / TPU-PEG-GO composite membrane a. Prepare solution A according to the preparation method in step (1), and add 0.25 g of graphene oxide under the condition of heating at 30 °C, stir evenly, and then continue to heat and let stand. After 5 min, spread the film on the PET release film and place it in an electrothermal constant temperature blast drying oven for curing. Among them, the curing temperature gradually rises from room temperature to 60 °C, and it is taken out after 2 h to obtain the TPU / PEG / GO membrane.

[0066] b. Coat Solution A on the strip of TPU / PEG / GO to obtain a composite film. Place the composite film in an oven and gradually heat it to 60 °C. After 2 h of curing, remove the composite film from the PET release film. Let it cool at room temperature. After cooling, the film material bends to obtain a solid composite film, namely the TPU-PEG / TPU-PEG-GO composite film.

[0067] (3)Preparation of PVDF / BaTiO3 fiber membrane Add BaTiO3 nanoparticles (0.1 g) to the prepared 5 g PVDF solution with a PVDF mass fraction of 12 wt% (the solvent is N,N-dimethylformamide), stir for 4 h, and then perform ultrasonic treatment for 2 h. Then, stir the PVDF / BaTiO3 solution at a rotation speed of 100 r / min and 45 °C for half an hour to obtain a spinning solution. The spinning solution is electrospun under the conditions of an applied voltage of 15 kV, a spinning distance of 13 cm, a drum collector (receiver) set at 1600 r.p.m, a flow rate of 11 mL / min, a chamber temperature of 33 °C, and an electrospinning current of 2 mA. After 2 h of electrospinning, the PVDF / BaTiO3 fiber membrane is prepared. Figure 1 Figure is the SEM image of the PVDF / BaTiO3 fiber membrane. It can be seen from the figure that the surface of the nanofibers is uneven, and there are multiple protrusions on the surface of each nanofiber. This is caused by the doping of BaTiO3 electret particles. These protrusions are generally nanoscale in size, which further increases the specific surface area of the nanofiber surface. Therefore, it will also have a certain promoting effect on the output performance of the generator.

[0068] Assembly of the bidirectional response type nanogenerator Use the TPU-PEG / TPU-PEG-GO composite film as the positive electrode and the PVDF / BaTiO3 fiber membrane as the negative electrode. Use copper tape as the friction layer part of the positive and negative electrodes. Stick both the TPU-PEG / TPU-PEG-GO composite film and the PVDF / BaTiO3 fiber membrane on the elastic PI plate. Then fold the PI plate in half so that the TPU-PEG / TPU-PEG-GO composite film and the PVDF / BaTiO3 fiber membrane are on both sides, so that contact separation can be carried out. When an external mechanical force acts on the elastic PI plastic plate to press the upper and lower fiber membranes to make the two membranes contact and rub against each other; when the external mechanical force is withdrawn, the upper and lower fiber membranes bounce off under the self-recovery and rebound of the PI plate, making the two layers of membranes in a separated state. Lead out copper foil on the back of the double-conductive copper tape as the electrode wire to connect the test system and the low-power load. Finally, assemble and make the triboelectric nanogenerator.

[0069] Example of implementation effect The conductive wire led out from the triboelectric nanogenerator is connected to a Keithley 2612b digital source meter, and the Keithley 2612b is connected to a computer. The PC controls the slider to act on the generator, and the digital source meter receives the converted electrical signal. The computer controls the reception, storage, and processing of the output electrical signal, and the output electrical signal can be directly observed from the computer display screen, such as Figure 2 a. Figure 2 Figure b is a simple measurement diagram of the performance of the triboelectric nanogenerator using a multimeter. It can be seen from the figure that the multimeter measures the performance parameters of the triboelectric nanogenerator, and the parameters displayed by it can help us initially understand the performance of the triboelectric nanogenerator, such as the output power and energy conversion efficiency. This is for more accurate testing and analysis of the performance of the triboelectric nanogenerator using a professional testing system later.

[0070] Figure 3 Figure shows the test results of the output electrical signal voltage V-t and current I-t of the sample. The figure shows the test results of the voltage and current of the triboelectric nanogenerator (TENG) changing with time. The current varies between -400 nA and 600 nA, and the voltage fluctuates between -150 V and 250 V. During the period from 50 seconds to 150 seconds, the current and voltage fluctuate violently because the frequency and amplitude of the mechanical motion increase, resulting in more frequent and significant charge transfer. In other time periods, the fluctuations are smaller, showing stability because the frequency and amplitude of the mechanical motion decrease or the motion pattern is more uniform. The TENG shows a higher energy conversion efficiency between 50 seconds and 150 seconds, indicating that the mechanical motion parameters in this period may reach the optimal matching state.

[0071] Figure 4 Figure shows the test result of the TENG lighting an LED light bulb. It can be seen from the figure that the TENG can effectively convert mechanical energy (such as mechanical motions like friction, vibration, and pressing) into electrical energy. The lighting of the LED light bulb indicates that this energy conversion process is effective. In addition, the TENG contains electret materials, and the experiment of lighting the LED can also prove that the electret effect has an obvious role in enhancing charge capture and charge storage.

[0072] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a bidirectional response type nanogenerator, characterized in that The steps are as follows: (1) Dissolve TPU in a solvent, add PEG1000 and a curing agent in sequence and dissolve them. After heating and standing, solution A is obtained; (2) Add graphene oxide to solution A to obtain solution B. After heating and standing, film spreading and curing, a TPU / PEG / GO film is obtained; Coat solution A on the surface of the TPU / PEG / GO film. After curing and cooling, a TPU-PEG / TPU-PEG-GO composite film is obtained; (3) Dissolve BaTiO3 nanoparticles in a PVDF solution and prepare a PVDF / BaTiO3 fiber membrane by electrospinning; (4) Using the TPU-PEG / TPU-PEG-GO composite film as the positive electrode and the PVDF / BaTiO3 fiber membrane as the negative electrode, a dual-responsive nanogenerator is prepared by assembly.

2. The preparation method of the bidirectional response type nanogenerator according to claim 1, wherein In the step (1), the addition amount of PEG 1000 is 10%-40% of the mass of TPU, and the mass ratio of TPU to the curing agent is 5: (1-2).

3. The preparation method of the bidirectional response type nanogenerator according to claim 2, wherein, In the step (1), 0.6-0.7 g of TPU is added to each gram of the solvent.

4. The preparation method of the bidirectional response type nanogenerator according to claim 3, wherein, In the solution B of the step (2), the graphene oxide is 1%-5% of the mass of TPU.

5. The preparation method of the bidirectional response type nanogenerator according to any one of claims 1-4, characterized in that, The solvent is N,N-dimethylformamide or tetrahydrofuran.

6. The preparation method of the bidirectional response type nanogenerator according to any one of claims 1-4, characterized in that, The curing agent is 4,4'-diaminodiphenylsulfone; the curing is to raise the temperature from room temperature to 60-100 °C and cure for 2-4 h.

7. The preparation method of the bidirectional response type nanogenerator according to claim 6, wherein, In the step (3), the content of PVDF in the PVDF solution is 12 wt%, and the solvent is N,N-dimethylformamide or tetrahydrofuran.

8. The preparation method of the bidirectional response type nanogenerator according to claim 7, wherein In the step (3), the mass ratio of the BaTiO3 nanoparticles to the mass of PVDF is 0.1-0.7:

1.

9. The preparation method of the bidirectional response type nanogenerator according to claim 8, characterized in that, The process parameters of the electrospinning in the step (3) are: the applied voltage is 15-20 kV, the injection speed is 11-22 mL / min, the receiving distance is 13-20 cm, the rotational speed of the receiver is 1600 r.p.m, the chamber temperature is controlled at 33-50 °C, and the spinning current is 2-5 mA.

10. A dual-responsive nanogenerator prepared by the preparation method according to any one of claims 1-4 or 7-9.

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