Gelatin / glycerol / tannic acid supramolecular material, preparation method thereof and friction nano generator

Abstract

The invention provides a gelatin / glycerol / tannic acid supramolecular material, a preparation method thereof and a friction nano-generator, the preparation method of the gelatin / glycerol / tannic acid supramolecular material comprises the following steps: S1, adding tannic acid into a mixed solution of water and glycerol, stirring, then adding gelatin, and stirring to obtain a gelatin / glycerol / tannic acid aqueous solution; and S2, drying the gelatin / glycerol / tannic acid aqueous solution to obtain the gelatin / glycerol / tannic acid supramolecular material. The gelatin / glycerol / tannic acid supramolecular material prepared by the invention has excellent mechanical properties and electrical conductivity, and the formed friction nano-generator has ultrahigh frictional electricity output performance.

Description

Technical Field

[0001] The invention belongs to the technical field of friction nano-power generation, and specifically relates to a gelatin / glycerol / tannic acid supramolecular material and a preparation method thereof, and a friction nano-generator. Background Art

[0002] With the rapid development of science and technology, energy crisis has come along, and it has also brought about environmental pollution problems. Triboelectric nanogenerator (TENG) is a new type of generator with a new method and principle, which can convert low-frequency mechanical energy in the environment into electrical energy and has broad application prospects in micro-energy collection.

[0003] In order to reduce environmental pollution, biomass materials such as cellulose and starch have been gradually introduced into the research of friction nanogenerators. However, biomass materials have weak ability to gain and lose electrons and poor mechanical properties. In order to obtain biomass materials with excellent triboelectric properties, a series of research strategies have been proposed, including high-performance friction material selection, ion implantation, surface physical / chemical modification and charge excitation. The performance has been improved, but the processing method is difficult and the technology is complex. The modified biomass materials can be used as friction layers and electrodes. Yang et al. reported that they used CNT@TA-Fe3+@Ag as filler and prepared hydrogel materials with gelatin and acrylamide as electrodes of TENG. Since the conductivity of hydrogel is difficult to match that of metal materials, the output voltage of the device is about 15V, which is far from the output of TENG with traditional hydrogel as friction layer material.

[0004] Therefore, the development of high-performance nanogenerator friction layer materials that are environmentally friendly, simple to prepare and have good mechanical properties remains a technical challenge that needs to be urgently solved in this field. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a gelatin / glycerol / tannic acid supramolecular material and a preparation method thereof and a friction nanogenerator. The gelatin / glycerol / tannic acid supramolecular material has excellent mechanical properties and electrical conductivity, and the friction nanogenerator composed of the material has ultra-high friction electric output performance.

[0006] The present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a method for preparing a gelatin / glycerol / tannic acid supramolecular material, comprising: S1, adding tannic acid to a mixed solution of water and glycerol, stirring, then adding gelatin, stirring, to obtain a gelatin / glycerol / tannic acid aqueous solution; S2, drying the gelatin / glycerol / tannic acid aqueous solution to obtain a gelatin / glycerol / tannic acid supramolecular material.

[0007] Preferably, in S1, the mass ratio of gelatin to tannic acid is 2.4:(0.15 - 0.3).

[0008] Preferably, in S1, the mass ratio of water to glycerol is (13 - 6):(2 - 9).

[0009] Preferably, in S1, the mass ratio of gelatin to glycerol is 2.4:(2 - 9).

[0010] Preferably, in S2, the drying temperature is 75 - 85 °C and the time is 5 - 7 h.

[0011] In a second aspect, the present invention provides a gelatin / glycerol / tannic acid supramolecular material obtained by the above preparation method.

[0012] In a third aspect, the present invention provides a triboelectric nanogenerator, comprising a positive electrode layer, a positive friction layer, a negative electrode layer, and a negative friction layer; the positive electrode layer and the positive friction layer are adhered, and the negative electrode layer and the negative friction layer are adhered; the positive friction layer and the negative friction layer are arranged opposite to each other; wherein, the positive friction layer is the gelatin / glycerol / tannic acid supramolecular material as claimed in claim 6.

[0013] Preferably, the negative friction layer is an Ecoflex film.

[0014] Preferably, both the positive electrode layer and the negative electrode layer are copper foils.

[0015] Preferably, the thickness of the positive friction layer is 0.75 - 3.3 mm, and the thickness of the negative friction layer is 120 - 810 μm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The triboelectric nanogenerator is based on the charge transfer caused by the different electron gain and loss abilities between the positive and negative friction layers. Based on this, the present invention introduces glycerol into gelatin containing a large number of electron-donating groups to construct a flexible ionic conductive network and reduce the internal resistance of the material; at the same time, the added tannic acid has abundant hydroxyl groups, which can form hydrogen bond interactions with gelatin, thereby constructing a supramolecular network structure and improving the mechanical properties of the material. Moreover, tannic acid also has electron-donating groups, making the supramolecular network structure form an electron-rich group system, further improving the conductivity of the material. Therefore, the positive friction layer material of the triboelectric nanogenerator constructed by the present invention has excellent mechanical properties and electrical conductivity, can reduce the electron migration resistance during compression, and cooperate with triboelectrification and electrostatic induction to further improve the output performance of the triboelectric nanogenerator. The overall manufacturing process and flow of the present invention are simple, and the prepared triboelectric nanogenerator can be used for energy harvesting. In addition, gelatin and glycerol are both biocompatible materials, and the prepared supramolecular has almost no impact on the environment.

[0017] The triboelectric nanogenerator of the present invention has excellent electrical output performance, with a maximum output voltage of up to 1250 V, a maximum current of 26 μA, and a maximum output power density of 5.5 W / m 2 . Through 80,000 cycles of testing on the prepared triboelectric nanogenerator, it is proved that it has the ability to output continuously and stably. Description of the Drawings

[0018] In order 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 use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are 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.

[0019] Figure 1 It is a diagram showing the influence of different glycerol contents on the triboelectric properties of gelatin / glycerol films in Example 1 of the present invention.

[0020] Figure 2 It is an infrared spectrum of the gelatin / glycerol / tannic acid supramolecular material corresponding to Example 2 of the present invention.

[0021] Figure 3 It is a scanning electron microscope image of gelatin and the gelatin / glycerol / tannic acid supramolecular material corresponding to Example 2 of the present invention.

[0022] Figure 4 It is a diagram showing the compressive mechanical properties of the gelatin / glycerol / tannic acid supramolecular material corresponding to Example 2 of the present invention.

[0023] Figure 5 It is a diagram showing the influence of different tannic acid contents on the triboelectric properties of the gelatin / glycerol / tannic acid supramolecular material corresponding to Example 2 of the present invention.

[0024] Figure 6 It shows the influence of different thicknesses of the gelatin / glycerol / tannic acid supramolecular material on the triboelectric properties of the device corresponding to Example 3 of the present invention.

[0025] Figure 7 It shows the influence of different thicknesses of the Ecoflex film on the triboelectric properties of the device corresponding to Example 3 of the present invention.

[0026] Figure 8 It is a diagram showing the influence of frequency on the open-circuit voltage of the assembled device corresponding to Example 4 of the present invention.

[0027] Figure 9 It is a diagram showing the influence of pressure on the open-circuit voltage of the assembled device corresponding to Example 5 of the present invention.

[0028] Figure 10It is the output current diagram of 8000 cycles of the assembled device corresponding to Embodiment 6 of the present invention.

[0029] Figure 11 It is the resistance change and voltage comparison diagram of the supramolecular material corresponding to Embodiment 6 of the present invention during the compression process.

[0030] Figure 12 It is the current and power density under different external load resistances corresponding to Embodiment 7 of the present invention.

[0031] Figure 13 It is the curve diagram of different capacitor chargings corresponding to Embodiment 7 of the present invention.

[0032] Figure 14 It is the curve diagram of power supply for low-power electronic devices corresponding to Embodiment 7 of the present invention. Detailed implementation manners

[0033] The following illustrates the implementation manners of the present invention through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0034] It should be noted that the process equipment or devices not specifically noted in the following embodiments all adopt conventional equipment or devices in the art.

[0035] It should be noted that the terms "include" and "have" and any of their variations are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, rather than limiting the arrangement order of each method step or the scope in which the present invention can be implemented. The change or adjustment of their relative relationships, without substantial change in technical content, should also be regarded as the scope in which the present invention can be implemented.

[0036] The preparation method of the gelatin / glycerol / tannic acid supramolecular material described in the present invention includes: S1. Add tannic acid to the mixed solution of water and glycerol, stir, and then add gelatin and stir to obtain an aqueous solution of gelatin / glycerol / tannic acid; S2. Dry the aqueous solution of gelatin / glycerol / tannic acid to obtain the gelatin / glycerol / tannic acid supramolecular material.

[0037] In some embodiments of the present invention, in S1, the mass ratio of gelatin to tannic acid is 2.4:(0.15 - 0.3).

[0038] In some embodiments of the present invention, in S1, the mass ratio of water to glycerol is (13 - 6):(2 - 9).

[0039] In some embodiments of the present invention, in S1, the mass ratio of gelatin to glycerol is 2.4:(2 - 9).

[0040] In some embodiments of the present invention, in S1, after adding gelatin, stir at 55 - 65 °C for 4 - 6 h. After stirring is completed, keep warm for 5 - 15 min to remove bubbles.

[0041] In some embodiments of the present invention, in S2, the drying temperature is 75 - 85 °C and the time is 5 - 7 h.

[0042] The gelatin / glycerol / tannic acid supramolecular material prepared by the above preparation method can be used as the positive friction layer to assemble a triboelectric nanogenerator, which specifically includes a positive electrode layer, a positive friction layer, a negative electrode layer, and a negative friction layer; the positive electrode layer and the positive friction layer are bonded, and the negative electrode layer and the negative friction layer are bonded; the positive friction layer and the negative friction layer are arranged opposite to each other; wherein, the positive friction layer is the gelatin / glycerol / tannic acid supramolecular material as described above.

[0043] In some embodiments of the present invention, the negative friction layer is an Ecoflex film.

[0044] In some embodiments of the present invention, both the positive electrode layer and the negative electrode layer are copper foils.

[0045] In some embodiments of the present invention, the thickness of the positive friction layer is 0.75 - 3.3 mm, and the thickness of the negative friction layer is 120 - 810 μm.

[0046] The triboelectric nanogenerator assembled with the gelatin / glycerol / tannic acid supramolecular material as the positive friction layer and the Ecoflex film prepared by the above preparation method has excellent electrical output performance under the test conditions of 30 N and 1.5 Hz. The maximum output voltage can reach 1250 V, the current is 21 μA, and it has good stability. The power density is 5.5 W / m 2 , and it can charge a 1 μF capacitor to 10 V in 40 s. As the capacitance of the capacitor increases, the charging rate will decrease; and it can supply energy for small - power electronic devices.

[0047] Example 1 Step 1: Dissolve 2.4 g of gelatin in mixed solutions where the mass of water and glycerol are 13 g and 2 g, 12 g and 3 g, 9 g and 6 g, 7.5 g and 7.5 g, 6 g and 9 g respectively. Then stir with a magnetic stirrer at 60 °C for 30 min. After removing all the bubbles, pour the obtained gelatin / glycerol aqueous solution into a square polytetrafluoroethylene mold with side length of 6 cm × 6 cm. Cool at room temperature for 15 min, and then put it into an oven and dry at 80 °C for 6 h to form a gelatin / glycerol film as the positive triboelectric layer.

[0048] Step 2: Attach a Cu electrode to a square polytetrafluoroethylene mold with side length of 6 cm × 6 cm. Mix 1.5 g of Ecoflex A liquid and 1.5 g of Ecoflex B liquid with 6 ml of diluent evenly, and pour it into the mold to prepare the negative triboelectric layer. Among them, Ecoflex A is a platinum-catalyzed silicone rubber matrix, and Ecoflex B is a platinum-catalyzed silicone rubber curing agent, both purchased from smooth-on company in the United States.

[0049] Step 3: Use the different gelatin / glycerol films in Step 1 as the positive triboelectric layer and attach a Cu electrode; use the Ecoflex film as the negative triboelectric layer, with the copper sheet on the back as the electrode, attach wires, and cut into devices with a size of 3 cm × 3 cm. Then bond the two Cu electrodes with triboelectric layers to a commercial acrylic plate (PP).

[0050] For the triboelectric nanogenerator assembled with the gelatin / glycerol film and the Ecoflex film obtained in this example, test its open-circuit voltage under the conditions of 1.5 Hz and 30 N. As Figure 1 shown, it is the graph of the influence of different glycerol contents on the triboelectric performance of the gelatin / glycerol film. Among them, Gt, Gt-Gc 2 、Gt-Gc 3 、Gt-Gc 6 、Gt-Gc 7.5 、Gt-Gc 9 correspond to the mass of water and glycerol being 13 g and 2 g, 12 g and 3 g, 9 g and 6 g, 7.5 g and 7.5 g, 6 g and 9 g respectively. Figure 1 The test results show that the introduction of glycerol can significantly increase the open-circuit voltage of the triboelectric nanogenerator assembled with the gelatin / glycerol film. For the triboelectric nanogenerator assembled when the mass of water and glycerol is 9 g and 6 g, the open-circuit voltage is up to 850 V.

[0051] Example 2 Step 1: Dissolve 0.15 g, 0.2 g, 0.25 g, and 0.3 g of tannic acid in a mixed solution of 9 g of water and 6 g of glycerol respectively. Then, stir at 500 rpm for 30 min with a magnetic stirrer at 60 °C until the tannic acid is completely dissolved. Add 2.4 g of gelatin to the above solution and stir for 4 h until the gelatin is completely dissolved. Keep warm for 10 min to remove bubbles, forming a homogeneous and stable solution. Inject the obtained gelatin / glycerol / tannic acid aqueous solution into a square polytetrafluoroethylene mold with side length 6 cm × 6 cm, cool at room temperature for 15 min, and then place it in an oven to dry at 80 °C for 6 h to form a gelatin / glycerol / tannic acid supramolecular material film as the positive friction layer.

[0052] Step 2: Attach the Cu electrode to a square polytetrafluoroethylene mold with side length 6 cm × 6 cm. Mix 1.5 g of Ecoflex A liquid and 1.5 g of Ecoflex B liquid with 6 ml of diluent evenly, and pour it into the mold to prepare the negative friction layer material. Among them, Ecoflex A is a platinum-catalyzed silicone rubber matrix, and Ecoflex B is a platinum-catalyzed silicone rubber curing agent, both purchased from Smooth-On, Inc., USA.

[0053] Step 3: Use the different gelatin / glycerol / tannic acid supramolecular material films in Step 1 as the positive friction layer respectively, and attach the Cu electrode; use the Ecoflex film as the negative friction layer, with the copper sheet on the back as the electrode, attach the wire, and cut it into a device with a size of 3 cm × 3 cm. Then bond the two Cu electrodes with friction layers to a commercial acrylic plate (PP).

[0054] As Figure 2 is the infrared spectrum of the gelatin / glycerol / tannic acid supramolecular material film (Gt-Gc 6 -Ta 0.25 ) formed with 0.25 g of tannic acid content. The vibration absorption peaks of gelatin are C-O (1182 cm -1 ), C=O (1649 cm -1 ), and N-H (3328 cm -1 , 3271 cm -1 ). The vibration absorption peak of tannic acid is -OH (3286 cm -1 ). The vibration absorption peaks of Gt-Gc 6 gel are -OH (3284 cm -1 ), C-O (1145 cm -1 ), C=O (1647 cm -1 ). The vibration absorption peaks of Gt-Gc 6 -TA 0.25 gel are -OH (3281 cm -1 ), C-O (1145 cm-1 ), C=O (1645 cm -1 ). It can be seen that Gt - Gc 6 -TA 0.25 All characteristic peaks of gelatin and tannic acid can be found in the gel. In addition, the high intensity and shift of the Gt - Gc - TA peak indicate that hydrogen bonds are formed between the functional groups of the gelatin side chain and the -OH of tannic acid and glycerol.

[0055] Such as Figure 3 are the microscopic morphology characterization results of the gelatin / glycerol / tannic acid supramolecular material film formed with 0.25 g of tannic acid content and gelatin at different magnification levels, where (a) - (c) are the microscopic morphology characterization results of gelatin, and (d) - (f) are the microscopic morphology characterization results of the gelatin / glycerol / tannic acid supramolecular material film. It can be seen from Figure 3 that the addition of glycerol and tannic acid causes the disappearance of the porous structure in gelatin.

[0056] Such as Figure 4 is the compressive mechanical property of the gelatin / glycerol / tannic acid supramolecular material film with 0.25 g of tannic acid content, 9 g of water and 6 g of glycerol. It can be seen that the compression and release curves of the material almost coincide and no fatigue occurs after multiple cycles, indicating that it can withstand long-term contact separation as a TENG device without affecting its material structure.

[0057] For the triboelectric nanogenerator assembled with the gelatin / glycerol / tannic acid supramolecular material film obtained in this example and the Ecoflex film, its open-circuit voltage is tested under the conditions of 1.5 Hz and 30 N. Such as Figure 5 shown, is the influence diagram of different tannic acid contents on the triboelectric performance of the gelatin / glycerol / tannic acid supramolecular material film. Among them, Gt - Gc 6 -Ta 0.15 , Gt - Gc 6 -Ta 0.2 , Gt - Gc 6 -Ta 0.25 , Gt - Gc 6 -Ta 0.3 correspond to tannic acid contents of 0.15 g, 0.2 g, 0.25 g, and 0.3 g respectively. Figure 5 The test results show that the introduction of tannic acid can significantly increase the open-circuit voltage of the triboelectric nanogenerator assembled with the gelatin / glycerol / tannic acid supramolecular material film. For the device assembled when the tannic acid content is 0.25 g, and the mass of water and glycerol is 9 g and 6 g, the open-circuit voltage is up to 1250 V.

[0058] Example 3 Step 1: Prepare supramolecular solutions with different volumes according to the mass ratio of gelatin: tannic acid: water: glycerol of 2.4:0.25:9:6. Inject them into a square polytetrafluoroethylene mold with a side length of 6 cm × 6 cm, cool at room temperature for 15 min, and then place them in an oven and dry at 80 °C for 6 h to form gelatin / glycerol / tannic acid supramolecular material films with thicknesses of 0.75, 1.04, 1.57, 1.71, 2.04, and 3.3 mm respectively, which are used as the positive friction layers.

[0059] Step 2: Mix 1.5 g, 1.2 g, 0.8 g, and 0.5 g of Ecoflex Liquid A and Ecoflex Liquid B respectively with 6 ml of diluent, inject them into a square polytetrafluoroethylene mold with a side length of 6 cm × 6 cm pasted with Cu to prepare the negative friction layer material, and after curing at room temperature for 6 h, Ecoflex films with thicknesses of 810 μm, 420 μm, 210 μm, and 120 μm are obtained respectively, which are used as the negative friction layers.

[0060] Step 3: Use the gelatin / glycerol / tannic acid supramolecular material films with different thicknesses prepared in Step 1 as the positive friction layers, paste Cu electrodes, and use the Ecoflex films with different thicknesses obtained in Step 2 as the negative friction layers, with Cu as the electrodes. Lead out a wire from the back of the copper electrodes respectively and fix them on the two contact-separation surfaces of the linear motor, set different contact-separation parameters to characterize the output performance of the triboelectric nanogenerator, and test its output performance under the contact-separation conditions of 1.5 Hz and 30 N.

[0061] As Figure 6 shown in the open-circuit voltage measured by assembling the triboelectric nanogenerator with the gelatin / glycerol / tannic acid supramolecular material films with different thicknesses as the positive friction layer and the 420-μm Ecoflex film, it can be seen that when the thickness of the gelatin / glycerol / tannic acid supramolecular material film is 2.04 mm, it has the best electrical output performance.

[0062] Take the 2.04-mm gelatin / glycerol / tannic acid supramolecular material film as the positive friction layer, pair it with the Ecoflex films with different thicknesses prepared in Step 2 to determine the thickness of the Ecoflex film with the best electrical output performance, and set the contact-separation parameters as above. As Figure 7 shown in the open-circuit voltage measured by assembling the triboelectric nanogenerator with the 2.04-mm gelatin / glycerol / tannic acid supramolecular material film as the positive friction layer and the Ecoflex films with different thicknesses, it can be seen that when the thickness of the positive friction layer gelatin / glycerol / tannic acid supramolecular material film is 2.04 mm and the thickness of the negative friction layer Ecoflex film is 210 μm, the triboelectric nanogenerator assembled with copper foil as the electrode has the best output performance, with a maximum open-circuit voltage of 1280 V.

[0063] In this example, the triboelectric nanogenerator assembled with the 2.04-mm-thick gelatin / glycerol / tannic acid supramolecular material and the 210-μm-thick Ecoflex film was tested for its open-circuit voltage under the conditions of 1.5 Hz and 30 N, and the highest open-circuit voltage was 1250 V.

[0064] Example 4 Step 1: Prepare a supramolecular solution with a mass ratio of gelatin: tannic acid: water: glycerol of 2.4: 0.25: 9: 6. Inject it into a square polytetrafluoroethylene mold with a side length of 6 cm × 6 cm, cool it at room temperature for 15 min, and then put it into an oven and dry it at 80 °C for 6 h to form a 1.9 - 2.1-mm-thick gelatin / glycerol / tannic acid supramolecular material film as the positive friction layer.

[0065] Step 2: Mix 0.8 g of Ecoflex A liquid and 0.8 g of Ecoflex B liquid with 6 ml of diluent, inject it into a square polytetrafluoroethylene mold with a side length of 6 cm × 6 cm pasted with Cu to prepare the negative friction layer material, and after curing at room temperature for 6 h, obtain a 210-μm-thick Ecoflex film as the negative friction layer.

[0066] Step 3: Use the gelatin / glycerol / tannic acid supramolecular material film prepared in Step 1 as the positive friction layer and paste a Cu electrode. Use the Ecoflex film obtained in Step 2 as the negative friction layer with Cu as the electrode. Lead out a wire from the back of the copper foil and fix them on the two contact-separation surfaces of the linear motor respectively.

[0067] Without the influence of other factors, the separation pressure was fixed at 30 N, and the triboelectric nanogenerator was driven at contact-separation frequencies of 0.5 Hz, 1 Hz, 1.5 Hz, and 2 Hz respectively, and its generated open-circuit voltage is as Figure 8 shown. Under the flapping at different frequencies, the increase in frequency leads to an increase in the contact-separation speed on the inner surface of the electrode layer, which is caused by the charge accumulation of the TENG in the contact-separation mode; the rising trends of the output open-circuit voltage and short-circuit current will slow down with the continuous increase of the contact-separation frequency, which is because the generation of frictional charges is an accumulation process. According to this characteristic shown in the contact-separation process of the positive and negative friction layers, this generator can be applied to detect the contact-separation frequency between two materials.

[0068] Example 5 Step 1: Prepare a supramolecular solution with a mass ratio of gelatin: tannic acid: water: glycerol of 2.4: 0.25: 9: 6. Inject it into a square polytetrafluoroethylene mold with a side length of 6 cm × 6 cm, cool it at room temperature for 15 min, and then put it into an oven and dry it at 80 °C for 6 h to form a 1.9 - 2.1-mm-thick gelatin / glycerol / tannic acid supramolecular material film as the positive friction layer.

[0069] Step 2: Mix 0.8 g of Ecoflex Liquid A and 0.8 g of Ecoflex Liquid B evenly with 6 ml of diluent, and inject the mixture into a square polytetrafluoroethylene mold with a Cu side length of 6 cm × 6 cm to prepare the negative friction layer. After curing at room temperature for 6 h, an Ecoflex film with a thickness of 210 μm is obtained as the negative friction layer.

[0070] Step 3: Use the gelatin / glycerol / tannic acid supramolecular material film prepared in Step 1 as the positive friction layer and attach a Cu electrode. Use the Ecoflex film obtained in Step 2 as the negative friction layer with Cu as the electrode. Lead out a wire from the back of the copper foil respectively and fix them on the two contact-separation surfaces of the linear motor.

[0071] Set the contact-separation frequency to 1.5 Hz and set different contact-separation pressures. When the pressure magnitudes are 30 N, 50 N, 80 N, and 110 N respectively, the open-circuit voltages generated are as Figure 9 shown. As the contact pressure increases, the contact between the friction layers will be closer, thus generating more induced charges correspondingly, and the electrical output performance of the TENG will increase accordingly. This is also related to the high elastic modulus of the Ecoflex film itself as the friction layer material.

[0072] Example 6 Step 1: Prepare a supramolecular solution with a mass ratio of gelatin:tannic acid:water:glycerol of 2.4:0.25:9:6. Inject it into a square polytetrafluoroethylene mold with a side length of 6 cm × 6 cm, cool at room temperature for 15 min, and then put it into an oven and dry at 80 °C for 6 h to form a gelatin / glycerol / tannic acid supramolecular material film with a thickness of 1.9 - 2.1 mm as the positive friction layer.

[0073] Step 2: Mix 0.8 g of Ecoflex Liquid A and 0.8 g of Ecoflex Liquid B evenly with 6 ml of diluent, and inject the mixture into a square polytetrafluoroethylene mold with a Cu side length of 6 cm × 6 cm to prepare the negative friction layer. After curing at room temperature for 6 h, an Ecoflex film with a thickness of 210 μm is obtained as the negative friction layer.

[0074] Step 3: Use the gelatin / glycerol / tannic acid supramolecular material film prepared in Step 1 as the positive friction layer and attach a Cu electrode. Use the Ecoflex film obtained in Step 2 as the negative friction layer with Cu as the electrode. Lead out a wire from the back of the copper foil respectively and fix them on the two contact-separation surfaces of the linear motor.

[0075] For the assembled triboelectric nanogenerator at a frequency of 1.5 Hz, a pressure of 30 N, and an effective contact area of 3 × 3 cm 2Under the contact-separation condition, 8,000 cycles of tests were carried out, and the device composed of the gelatin / glycerol / tannic acid supramolecular material film and the Ecoflex film showed excellent stability as Figure 10 .

[0076] Under the test conditions of a frequency of 1.5 Hz and a pressure of 30 N, the resistance change of the gelatin / glycerol / tannic acid supramolecular material film was monitored as Figure 11 . During compression, the resistance decreased instantaneously, reducing the hindrance to electron migration. At the same time, in synergy with triboelectrification and electrostatic induction, the output performance of the triboelectric nanogenerator was further improved.

[0077] Example 7 Step 1: Prepare a supramolecular solution with a mass ratio of gelatin:tannic acid:water:glycerol of 2.4:0.25:9:6. Inject it into a square polytetrafluoroethylene mold with a side length of 6 cm × 6 cm, cool it at room temperature for 15 min, and then put it into an oven and dry it at 80 °C for 6 h to form a gelatin / glycerol / tannic acid supramolecular material film with a thickness of 1.9 - 2.1 mm as the positive friction layer.

[0078] Step 2: Mix 0.8 g of Ecoflex A liquid and 0.8 g of Ecoflex B liquid with 6 ml of diluent evenly, inject it into a square polytetrafluoroethylene mold with a side length of 6 cm × 6 cm pasted with Cu to prepare the negative friction layer, and after curing at room temperature for 6 h, obtain an Ecoflex film with a thickness of 210 μm as the negative friction layer.

[0079] Step 3: Use the gelatin / glycerol / tannic acid supramolecular material film prepared in Step 1 as the positive friction layer and paste a Cu electrode. Use the Ecoflex film obtained in Step 2 as the negative friction layer with Cu as the electrode. Lead out a wire from the back of the copper foil and fix it on the two contact-separation surfaces of the linear motor respectively.

[0080] Step 4: For the assembled triboelectric nanogenerator under the contact-separation condition of a frequency of 1.5 Hz, a pressure of 30 N, and an effective contact area of 3 × 3 cm 2 , test its short-circuit current by connecting different-sized resistors in series in the external circuit, and calculate the power density according to P = I 2 ²R / S, as Figure 12 After testing, its maximum output power density is 5.5 W / m 2 .

[0081] Step 5: Under the test conditions of Step 4, the assembled triboelectric nanogenerator converts alternating current (AC) into direct current (DC) by using a bridge rectifier and charges different capacitors (1 μF, 4.7 μF, 10 μF, 47 μF, 100 μF, 470 μF). It is found that the 1 μF capacitor is filled in a very short time, and the charging time gradually increases with the increase of capacitance as Figure 13 .

[0082] Step 6: Under the test conditions of 4, the assembled triboelectric nanogenerator powers low-power electronic devices. First, the 47 μF capacitor is charged to a voltage of about 1.5 V within 200 s by using the TENG device. Then, it can drive the power supply to a calculator with a voltage of 1.5 V, and the calculator works stably as Figure 14 .

[0083] The triboelectric nanogenerator assembled with the gelatin / glycerol / tannic acid supramolecular material film and the Ecoflex film obtained in this embodiment can be successfully applied to energy harvesting. Under the conditions of 1.5 Hz and 30 N, its maximum power density is 5.5 W / m 2 ; it can charge a 1 μF capacitor to 10 V in 40 s. As the capacitance of the capacitor increases, the charging rate will decrease; and it can supply energy for low-power electronic devices.

Claims

1. A method for preparing a gelatin / glycerol / tannic acid supramolecular material, characterized in that: include: S1, adding tannic acid to a mixed solution of water and glycerol, stirring, then adding gelatin, stirring, to obtain a gelatin / glycerol / tannic acid aqueous solution; S2, drying the gelatin / glycerol / tannic acid aqueous solution to obtain a gelatin / glycerol / tannic acid supramolecular material.

2. The method for preparing the gelatin / glycerol / tannic acid supramolecular material according to claim 1, characterized in that: In S1, the mass ratio of gelatin to tannic acid is 2.4:(0.15-0.3).

3. The method for preparing the gelatin / glycerol / tannic acid supramolecular material according to claim 1, characterized in that: In S1, the mass ratio of water to glycerol is (13-6): (2-9).

4. The method for preparing the gelatin / glycerol / tannic acid supramolecular material according to claim 1, characterized in that: In S1, the mass ratio of gelatin to glycerol is 2.4:(2-9).

5. The method for preparing the gelatin / glycerol / tannic acid supramolecular material according to claim 1, characterized in that: In S2, the drying temperature is 75-85°C and the time is 5-7h.

6. The gelatin / glycerol / tannic acid supramolecular material obtained by the preparation method according to any one of claims 1 to 5.

7. A friction nanogenerator, characterized in that: It includes a positive electrode layer, a positive friction layer, a negative electrode layer, and a negative friction layer; the positive electrode layer and the positive friction layer are bonded together, and the negative electrode layer and the negative friction layer are bonded together; the positive friction layer and the negative friction layer are arranged opposite to each other; wherein the positive friction layer is the gelatin / glycerol / tannic acid supramolecular material as described in claim 6.

8. The triboelectric nanogenerator according to claim 7, characterized in that: The negative electrode friction layer is an Ecoflex film.

9. The triboelectric nanogenerator according to claim 7, characterized in that: The positive electrode layer and the negative electrode layer are both copper foils.

10. The triboelectric nanogenerator according to claim 7, characterized in that: The thickness of the positive electrode friction layer is 0.75-3.3 mm, and the thickness of the negative electrode friction layer is 120-810 μm.

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