Aerogel film triboelectric material suitable for full humidity environment and preparation method thereof

Abstract

The application discloses an aerogel film triboelectric material suitable for full-humidity environment and a preparation method thereof, and belongs to the technical field of functional materials. The preparation method comprises the following technical steps: (1) taking a chitosan and polyvinyl alcohol solution, dissolving the chitosan and polyvinyl alcohol solution in water, uniformly mixing after mechanical stirring, then adding acetic acid, and obtaining a mixed solution through ultrasonic treatment; (2) performing directional freezing on the mixed solution to obtain a block-shaped gel; (3) performing low-temperature preservation on the block-shaped gel, and then performing freeze-drying to obtain an aerogel material; (4) performing cold pressing forming on the aerogel material, and then performing drying in an oven to obtain the aerogel film triboelectric material suitable for full-humidity environment. The material prepared by the application still has high output electric performance in an extremely high humidity environment (RH 99%), solves the problems that triboelectric materials are charge dissipation and electric performance attenuation under high humidity conditions, and provides a new idea for the construction and application of functional materials under full-humidity environment conditions.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to an aerogel film triboelectric material suitable for all humidity environments and its preparation method. Background Technology

[0002] Triboelectric nanogenerators (TENGs) are a novel type of power generation device that converts mechanical energy into electrical energy. Among various energy harvesting devices, they have emerged as a self-powered device with great development potential. Because TENGs can harvest energy from the surrounding environment and convert it into electrical energy, and possess characteristics such as high output voltage, low cost, and simple structure, they are suitable for use in portable soft electronic devices. In recent years, TENGs applied to extreme environments (high temperature, high humidity, high corrosion, and radiation, etc.) have been extensively studied. However, in high humidity environments, TENGs suffer from charge dissipation, resulting in a significant degradation in their output electrical performance. Therefore, stabilizing and improving the electrical performance of TENGs in high humidity environments and expanding their application in self-powered devices presents significant challenges.

[0003] Chitosan (CS), also known as deacetylated chitin, is a product of chitin after the de-N-acetylation. It is mainly derived from animal shells, fungi, and the cell walls of higher plants. It is a non-toxic, biocompatible, biodegradable natural polysaccharide polymer with excellent broad-spectrum antibacterial properties. Chitosan is insoluble in water but soluble in acidic aqueous solutions. Its molecular chain contains numerous hydroxyl and amino groups; under acidic conditions, these amino groups are protonated, resulting in a positive charge. However, chitosan also has significant drawbacks: poor water resistance, brittle and easily degraded films, easy solubility in acid, and slightly insufficient mechanical properties. These shortcomings hinder its widespread application.

[0004] Polyvinyl alcohol (PVA) is a white granular or powdery substance with the molecular formula (C2H4O)n. Due to the relatively large number of hydroxyl groups (-OH) in its molecular chain, PVA is hygroscopic and soluble in water. Composite materials made from PVA exhibit relatively poor mechanical properties and insufficient water resistance. Because PVA contains numerous hydroxyl groups, it can form hydrogen bonds with chitosan. Therefore, blending PVA and chitosan can improve the water resistance of chitosan. Simultaneously, the good toughness of PVA can optimize and improve the brittleness of chitosan, thus enhancing the physical and mechanical properties of chitosan materials after blending.

[0005] Based on the above-mentioned problems, it is necessary to develop a method for preparing aerogel film triboelectric materials with chitosan and polyvinyl alcohol as the substrate, so as to solve the problems of charge dissipation and electrical performance degradation of triboelectric materials under high humidity environment conditions. Summary of the Invention

[0006] To address the above problems, this invention utilizes chitosan and polyvinyl alcohol as substrates and employs a combination of directional freezing, freeze-drying, and cold-pressing processes to prepare aerogel film triboelectric materials. These materials retain high electrical output performance even under high humidity conditions, thus solving the problems of charge dissipation and electrical performance degradation in triboelectric materials under high humidity conditions.

[0007] This invention is achieved through the following technical solution:

[0008] A method for preparing aerogel film triboelectric materials suitable for use in all humidity environments includes the following steps:

[0009] (1) Take chitosan and polyvinyl alcohol solution and dissolve them in water. Mix them evenly after mechanical stirring. Then add acetic acid, sonicate, and let stand to obtain a mixed solution.

[0010] (2) The mixed solution is introduced into a mold for directional freezing to obtain a frozen block gel;

[0011] (3) The block gel is placed in a refrigerator for low-temperature storage, and then freeze-dried to obtain the aerogel material;

[0012] (4) The aerogel material is cold-pressed using a flat vulcanizing machine and then dried in an oven to obtain an aerogel film triboelectric material suitable for all humidity environments.

[0013] Further, in step (1), the mass ratio of chitosan to polyvinyl alcohol solution, water, and acetic acid is 2 g : 4-10 mL : 85-95 mL : 1-2 mL; the mass percentage of the polyvinyl alcohol solution is 8-10 wt%.

[0014] Further, in step (1), the mechanical stirring speed is 300-400 rpm and the time is 4-5 h; the ultrasonic treatment time is 8-10 min.

[0015] Further, in step (2), the directional freezing uses anhydrous ethanol as the cold source, the bottom of the mold is in contact with and parallel to the surface of the anhydrous ethanol, the temperature gradient is -80 to 25°C, the mold sinks 1 cm every 0.5 h, and freezing lasts for 2 to 2.5 h.

[0016] Further, in step (2), the mold is a rectangular open container with a heat-conducting bottom and heat-insulating sides, with dimensions of (5~10)cm × (0.5~1)cm × (5~10)cm. The container is surrounded by acrylic material, wrapped with heat-insulating cotton, and sealed with glass sheets at the bottom.

[0017] Furthermore, in step (3), the temperature for cryopreservation is -20 to -22°C, and the time is 0.5 to 1 h.

[0018] Furthermore, in step (3), the vacuum degree of the freeze drying is 15 to 20 Pa, the temperature is -70 to -80°C, and the time is 45 to 48 h.

[0019] Further, in step (4), the pressure of the cold pressing is 0.8 to 1.2 MPa, the temperature is 24 to 26°C, and the time is 1 to 2 min; the compression direction of the aerogel material is parallel to the direction of ice crystal growth.

[0020] Furthermore, in step (4), the drying temperature in the oven is 45-50°C and the drying time is 22-24 h.

[0021] An aerogel film triboelectric material suitable for all humidity environments was prepared by the method described above.

[0022] The preparation principle of the aerogel film triboelectric material applicable to all humidity environments of the present invention is as follows:

[0023] This invention mixes chitosan and polyvinyl alcohol solutions. Since chitosan is insoluble in water, acetic acid is added to dissolve the chitosan. In the resulting mixed solution, chitosan and polyvinyl alcohol undergo physical cross-linking, including the formation of cross-linked network structures within and between chitosan molecules (between -OH, -NH2 and -OH), the formation of cross-linked network structures within and between polyvinyl alcohol molecules (between -OH), and the formation of hydrogen bonds between chitosan and polyvinyl alcohol (the -OH and -NH2 of chitosan and the -OH of polyvinyl alcohol).

[0024] During the directional freezing of a mixture of chitosan and polyvinyl alcohol, the bottom of the mold contacts the cold source, creating a bottom-up temperature gradient, causing ice crystals to grow from the bottom. Due to the low viscosity of the solution, the movement of chitosan and polyvinyl alcohol chains is almost unrestricted, and they grow along with the directional growth of the ice crystals. The molecular chains enter the gaps between the ice crystals, forming a layered, honeycomb-like porous block gel. Freeze-drying the block gel removes the ice crystals and moisture. Subsequent cold-pressing shortens the spacing between the components, reducing the pore size of the aerogel film and effectively improving its mechanical properties, dimensional stability, and triboelectric effect, thus enhancing its stability.

[0025] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0026] 1. This invention produces an aerogel film triboelectric material using chitosan and polyvinyl alcohol as substrates, employing a combination of directional freezing, freeze-drying, and cold-pressing processes. The material exhibits a rough, porous surface structure and a layered cross-section. It retains high electrical output performance even under extremely high humidity conditions (RH 99%), solving the problems of charge dissipation and electrical performance degradation in triboelectric materials under high humidity conditions. This provides a new approach for the construction and application of functional materials under all humidity environments.

[0027] 2. The present invention utilizes a combination of directional freezing, freeze-drying, and cold-pressing processes to create a more rough and porous surface for the aerogel film material. This porous structure increases electrostatic induction, allowing for the formation of more charges on the porous surface. Simultaneously, the film's oriented structure forms a neat and compact arrangement, concentrating the electrostatic effect and resulting in a higher output voltage. Therefore, it exhibits high electrical performance under normal temperature and humidity conditions. Under high humidity conditions, the abundant hydrophilic groups -OH and -NH2 in the material can bind with free water molecules in the air, fixing them to participate in friction, thus enhancing its electrical performance compared to normal humidity conditions. Furthermore, the rough and porous structure of the material increases the adsorption sites for water molecules, thereby enhancing the material's electrical performance under extremely high humidity conditions.

[0028] 3. The chitosan aerogel membrane triboelectric material of this invention can effectively convert electrical energy, and the added polyvinyl alcohol can improve the mechanical properties of chitosan. Polyvinyl alcohol contains abundant hydrogen bonds, as does the hydrogen bonds formed by the combination of chitosan and polyvinyl alcohol, which can compensate for the problem of the material's inability to recover quickly after absorbing water, thus preventing cracking. The presence of numerous amino groups in the chitosan molecules within the material's network provides excellent electron-donating affinity, resulting in high output electrical performance. Furthermore, the material is biodegradable; therefore, it has the potential to serve as a positive friction layer material in triboelectric nanogenerators.

[0029] 4. The aerogel film triboelectric material of this invention exhibits high output electrical performance. Using it as the positive electrode material and the FEP film as the negative electrode material to form a vertical-contact separation mode TENG, tests show a maximum current of 13.35 μA, a maximum charge density of 39.9 nC, and a maximum voltage of 214 V. In environments with low relative humidity (<55% RH), the voltage drop is small; as humidity increases, the voltage rises slowly, reaching a maximum of 128.8 V in extremely high relative humidity environments (99% RH). After the material becomes saturated with moisture, the voltage (155.1 V) in extremely high relative humidity environments (99% RH) is 153.1% higher than the voltage (101.3 V) in normal humidity environments (50% RH). Therefore, using this material as the positive-positive triboelectric layer material of the TENG can significantly improve the output electrical performance of the TENG in high humidity environments. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of directional freezing in Example 3.

[0031] Figure 2 This is a SEM image of the surface of the aerogel material in Example 3 at 1000x magnification.

[0032] Figure 3 The image shows a cross-section of the aerogel material in Example 3 at 1000x magnification using an SEM.

[0033] Figure 4 This is a SEM image of the surface of the aerogel film triboelectric material of Example 3 at 500x magnification.

[0034] Figure 5 The image shows the surface of the aerogel film triboelectric material of Example 3 at 10,000x magnification.

[0035] Figure 6 The image shows a cross-section of the aerogel film triboelectric material of Example 3 at 1000x magnification.

[0036] Figure 7 The image shows a cross-section of the aerogel film triboelectric material of Example 3 at a magnification of 6000.

[0037] Figure 8 The images show the FTIR spectra of the aerogel film triboelectric materials of Examples 1-4.

[0038] Figure 9 The current diagrams are for the aerogel film triboelectric materials of Examples 1-4.

[0039] Figure 10 The charge density diagrams are for the aerogel film triboelectric materials of Examples 1-4.

[0040] Figure 11 The voltage diagrams are for the aerogel film triboelectric materials of Examples 1-4.

[0041] Figure 12 The voltage diagrams for the aerogel film triboelectric material of Example 3 under different relative humidity environments are shown.

[0042] Figure 13 The voltage diagrams for the aerogel film triboelectric material of Example 3 after moisture absorption saturation under different relative humidity environments are shown. Detailed Implementation

[0043] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of protection of the present invention.

[0044] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of protection of the present invention.

[0045] Example 1

[0046] Suitable for the preparation of aerogel film triboelectric materials in all humidity environments:

[0047] Take 2 g of chitosan and 10 mL of 10 wt% PVA solution, dissolve them in 86.24 mL of deionized water, and mechanically stir (300 rpm) for 5 h at room temperature until homogeneous. Then add 1.76 mL of acetic acid, sonicate for 10 min to remove bubbles, and let stand to obtain a mixed solution (the mass ratio of chitosan to PVA is 2:1). Transfer the mixed solution to a mold for directional freezing. The mold is a rectangular open container with a heat-conducting bottom and insulated sides, with dimensions of 5 cm × 0.5 cm × 5 cm. The container is surrounded by acrylic material and wrapped with thermal insulation cotton. The bottom is sealed with a glass plate. Place the mold containing the mixed solution on an anhydrous ethanol cold source, with the glass plate at the bottom of the mold touching and parallel to the liquid surface. The temperature gradient is -80 to 25℃. The mold sinks 1 cm every 0.5 h and is frozen for 2 h to obtain a formed block gel. The block gel was stored in a -22°C freezer for 0.5 h. The block gel was then removed from the mold and freeze-dried at a vacuum of 15 Pa and a temperature of -80°C for 45 h to obtain a dried aerogel material. The aerogel material was compressed using a flatbed vulcanizing machine at a temperature of 26°C, a pressure of 0.8 MPa, and a time of 1 min. It was then dried in an oven at a temperature of 45°C for 20 h to obtain an aerogel film triboelectric material suitable for use in all humidity environments.

[0048] Example 2

[0049] Suitable for the preparation of aerogel film triboelectric materials in all humidity environments:

[0050] Take 2 g of chitosan and 6.7 mL of 10 wt% PVA solution, dissolve them in 89.5 mL of deionized water, and mechanically stir (400 rpm) for 4 h at room temperature until homogeneous. Then add 1.83 mL of acetic acid, sonicate for 8 min to remove bubbles, and let stand to obtain a mixed solution (the mass ratio of chitosan to PVA is 3:1). Transfer the mixed solution to a mold for directional freezing. The mold is a rectangular open container with a heat-conducting bottom and insulated sides, with dimensions of 5 cm × 0.5 cm × 5 cm. The sides of the container are made of acrylic material and wrapped with thermal insulation cotton. The bottom is sealed with a glass plate. Place the mold containing the mixed solution on an anhydrous ethanol cold source, with the glass plate at the bottom of the mold touching and parallel to the liquid surface. The temperature gradient is -80 to 25℃. The mold sinks 1 cm every 0.5 h and is frozen for 2 h to obtain a formed block gel. The block gel was stored in a -20°C freezer for 0.5 h. The block gel was then removed from the mold and freeze-dried at a vacuum of 20 Pa and a temperature of -70°C for 45 h to obtain a dried aerogel material. The aerogel material was compressed using a flatbed vulcanizing machine at a temperature of 24°C, a pressure of 1 MPa, and a time of 1 min. It was then dried in an oven at a temperature of 45°C for 24 h to obtain an aerogel film triboelectric material suitable for use in all humidity environments.

[0051] Example 3

[0052] Suitable for the preparation of aerogel film triboelectric materials in all humidity environments:

[0053] Take 2 g of chitosan and 5 mL of 10 wt% PVA solution, dissolve them in 91.14 mL of deionized water, and mechanically stir (300 rpm) for 5 h at room temperature until homogeneous. Then add 1.86 mL of acetic acid, sonicate for 10 min to remove bubbles, and let stand to obtain a mixed solution (the mass ratio of chitosan to PVA is 4:1). Transfer the mixed solution to a mold for directional freezing. The mold is a rectangular open container with a heat-conducting bottom and insulated sides, measuring 5 cm × 0.5 cm × 5 cm. The container is surrounded by acrylic material and wrapped with insulating cotton. The bottom is sealed with a glass plate. Place the mold containing the mixed solution on an anhydrous ethanol cold source, with the glass plate at the bottom of the mold touching and parallel to the liquid surface. The temperature gradient is -80 to 25℃. The mold sinks 1 cm every 0.5 h, and is frozen for 2.5 h. Figure 1As shown, a shaped block gel was obtained. The block gel was stored in a -20°C freezer for 1 hour. The block gel was then removed from the mold and freeze-dried at a vacuum of 15 Pa and a temperature of -80°C for 48 hours to obtain a dried aerogel material. The aerogel material was compressed using a flat vulcanizing machine at a temperature of 25°C, a pressure of 1 MPa, and a time of 1 minute. It was then dried in an oven at a temperature of 50°C for 24 hours to obtain an aerogel film triboelectric material suitable for use in all humidity environments.

[0054] Example 4

[0055] Suitable for the preparation of aerogel film triboelectric materials in all humidity environments:

[0056] Take 2 g of chitosan and 4 mL of 10 wt% PVA solution, dissolve them in 91.12 mL of deionized water, and mechanically stir (400 rpm) for 4 h at room temperature until homogeneous. Then add 1.88 mL of acetic acid, sonicate for 10 min to remove bubbles, and let stand to obtain a mixed solution (the mass ratio of chitosan to PVA is 5:1). Transfer the mixed solution to a mold for directional freezing. The mold is a rectangular open container with a heat-conducting bottom and insulated sides, with dimensions of 5 cm × 0.5 cm × 5 cm. The container is surrounded by acrylic material and wrapped with insulating cotton. The bottom is sealed with a glass plate. Place the mold containing the mixed solution on an anhydrous ethanol cold source, with the glass plate at the bottom of the mold touching and parallel to the liquid surface. The temperature gradient is -80 to 25℃. The mold sinks 1 cm every 0.5 h, and is frozen for 2.5 h to obtain a formed block gel. The block gel was stored in a -20°C freezer for 1 hour. The block gel was then removed from the mold and freeze-dried at a vacuum of 15 Pa and a temperature of -80°C for 48 hours to obtain a dried aerogel material. The aerogel material was compressed using a flatbed vulcanizing machine at a temperature of 25°C, a pressure of 1.2 MPa, and a time of 2 minutes. It was then dried in an oven at 50°C for 24 hours to obtain an aerogel film triboelectric material suitable for use in all humidity environments.

[0057] Material characterization analysis

[0058] (I) SEM Analysis

[0059] The aerogel material and aerogel film triboelectric material in Example 3 were characterized and analyzed using scanning electron microscopy (SEM). The analysis results are as follows: Figures 2-7 As shown, Figure 2 and Figure 3 The images show SEM images of the surface and cross-section of the aerogel material, respectively. Figures 4-7 The images show SEM images of the surface and cross-section of the aerogel film triboelectric material at different magnifications.

[0060] Depend on Figure 2 and Figure 3 It is known that the surface of aerogel materials has a honeycomb-like porous structure, with wrinkled pore walls and interconnected pores. These pores and wrinkles on the pore wall surface are formed due to the loss of moisture during freeze-drying. The cross-section of aerogel materials is composed of continuous stacked parallel sheets. This is because during directional freezing, molecular chains grow along the direction of ice crystals, becoming hard templates for forming pores, causing solutes in the solution to be squeezed into the spaces between ice crystals to obtain an oriented structure. After freeze-drying, moisture is lost, and the solute retains its original morphology.

[0061] Depend on Figure 4 and Figure 5 It can be seen that the surface of the aerogel film triboelectric material exhibits a rough porous structure, with the solute arranged in parallel and uniformly distributed pores. From Figure 6 and Figure 7 It is known that the cross-section of the aerogel film triboelectric material has a vertically aligned layered structure with small pores distributed between the layers. This is because after cold pressing, the spacing between the components is shortened, the porosity of the material decreases, the density increases, the surface structure becomes rough and porous, and the cross-section exhibits a layered structure.

[0062] (ii) FT-IR analysis

[0063] The aerogel film triboelectric materials prepared in Examples 1-4 were characterized and analyzed using Fourier transform infrared spectroscopy (FT-IR). The analytical results are as follows: Figure 8 As shown. Figure 8 In this context, Pure CS, Pure PVA, CP-21, CP-31, CP-41, and CP-51 represent pure chitosan, pure polyvinyl alcohol, and aerogel film triboelectric materials prepared by chitosan and polyvinyl alcohol in different mass ratios (2:1, 3:1, 4:1, and 5:1) in Examples 1-4, respectively.

[0064] Depend on Figure 8 It can be seen that the OH absorption peak of pure chitosan is at 3294 cm⁻¹. -1 The CH absorption peak is at 2865 cm⁻¹ -1 1636 cm -1 and 1560 cm -1 The absorption band is attributed to the stretching vibration of C=O (amide I) and the bending vibration of −NH2 (amide II); 1377 cm⁻¹ -1 and 1062 cm -1 The absorption bands are due to the scissor vibration of the -NH2 group and the stretching vibration of the C−O−C glycosidic bond in the polymer. The OH absorption peak of pure PVA is at 3280 cm⁻¹. -1 The CH absorption peak is at 2915 cm⁻¹. -11716 cm -1 For the second bending and stretching of O−H; 1087 cm -1 For C−H angular deformation; 1023 cm -1 The stretching is due to the C−O groups. Comparing the infrared spectra of the aerogel triboelectric material with those of the pure polymer, it can be seen that as the PVA content increases, the OH vibration peak of the composite film gradually shifts towards the higher wavenumber region (i.e., a blue shift). This indicates that the addition of PVA disrupts the intramolecular and intermolecular hydrogen bonds of the original chitosan molecules, and the hydroxyl groups on both macromolecules are highly likely to undergo intermolecular association. 3000–3600 cm⁻¹ -1 The overlapping and downward stretching of nearby vibrational bands confirms the formation of hydrogen bonds between the −OH and −NH groups of chitosan and the −OH group of PVA. The introduction of further components did not produce new characteristic peaks, indicating that no chemical reaction occurred between the two materials during the crosslinking process, and no new chemical bonds were formed; the mixture is considered a physical mixture.

[0065] Material property testing

[0066] (a) Electrical performance testing

[0067] Pure chitosan and the aerogel film triboelectric materials prepared in Examples 1-4 were cut into 3 cm × 3 cm squares and attached to an acrylic plate with conductive adhesive as the positive electrode material. A fluorinated ethylene propylene copolymer (FEP) film of the same size was cut as the negative electrode material and also attached to the acrylic plate with conductive adhesive. The positive and negative electrode plates were mounted on a TENG electrical test bench to form a TENG in a vertical-contact separation mode. Testing was conducted at a frequency of 2 Hz, and the test results are as follows: Figures 9-11 As shown. Figures 9-11 In the text, Pure CS, CP-21, CP-31, CP-41, and CP-51 represent pure chitosan, aerogel film triboelectric materials prepared by chitosan and polyvinyl alcohol in different mass ratios (2:1, 3:1, 4:1, and 5:1) in Examples 1-4, respectively.

[0068] Depend on Figure 9 It can be seen that when the mass ratio of chitosan to polyvinyl alcohol in Example 3 is 4:1, the current of the prepared aerogel film triboelectric material is 13.35 μA, which is higher than that of pure chitosan and the materials in Examples 1, 2, and 4. Figure 11It was found that when the mass ratio of chitosan to polyvinyl alcohol in Example 3 was 4:1, the voltage of the material was the highest, at 214 V. The voltage of pure chitosan was relatively low because chitosan contains a large number of amino and hydroxyl groups, and its structure itself easily generates a large number of hydrogen bonds, which restricts the reorientation space of polarization groups, thus affecting their mobility. The voltage increased after adding PVA because PVA increases the mobility of polarization molecular groups, thereby enhancing the dielectric constant of the blend. When a small amount of PVA was added (Example 4), the crystal structure of the blend changed, directly increasing the boundary between crystalline and amorphous regions, thereby enhancing interfacial polarization and increasing the dielectric constant. The voltage was highest when an appropriate amount of PVA was added (Example 3). However, when excessive PVA was added (Examples 1 and 2), although the interfacial area increased, the increase in hydrogen bonds reduced the mobility of polarization groups in chitosan, thereby reducing the dielectric constant and resulting in a decrease in output voltage.

[0069] Depend on Figure 10 It can be seen that when the mass ratio of chitosan to polyvinyl alcohol in Example 1 is 2:1, the charge density of the prepared aerogel film triboelectric material is 39.9 nC. Adding different amounts of PVA results in different mechanical strengths and slight differences in the degree of compression. Higher PVA content leads to lower compression, higher density, and higher porosity. The porous structure can lead to increased electrostatic induction, thereby allowing more charges to form on the porous surface. Therefore, the material in Example 1 has the highest surface charge density.

[0070] (ii) Electrical performance testing under different relative humidity environments

[0071] When testing the electrical performance under different humidity conditions, the TENG device was placed in a sealed container, and the relative humidity of the sealed container was adjusted to 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 99% using a humidifier. The aerogel film triboelectric material prepared in Example 3 was cut into 2 cm × 2 cm squares and attached to an acrylic plate with conductive adhesive as the positive electrode material. A fluorinated ethylene propylene copolymer (FEP) film of the same size was cut as the negative electrode material and also attached to an acrylic plate with conductive adhesive. The positive and negative electrode plates were respectively mounted on a sealed TENG electrical test bench, forming a TENG in a vertical-contact separation mode. Testing was performed at a frequency of 2 Hz, and the test results are as follows: Figure 12 As shown.

[0072] Depend on Figure 12It can be seen that in an environment with low relative humidity (<55% RH), when the relative humidity increases from 10% to 50%, the voltage changes from 122.2 V to 117.2 V, with a voltage drop rate of 4.1%, which is relatively small. This is because the material is hydrophobic at this temperature, and the water molecule content in the sealed container is low. Only a very small portion of the free water molecules participate in the contact separation of the positive and negative electrode materials, and the water molecules carry away a very small amount of charge. When the relative humidity becomes 60%, the voltage is 110.3 V, which is the lowest voltage, because the number of free water molecules is the highest at this temperature. As the relative humidity increases, the voltage rises slowly, reaching 128.5 V and 128.8 V at 90% and 99% RH, respectively. This is because during the humidification process, water molecules and the positive electrode material form hydrogen bonds, fixing a small portion of bound water on the membrane surface to participate in friction, thus enhancing the electrical properties of the material.

[0073] (III) Electrical performance testing under different relative humidity environments after moisture absorption saturation

[0074] Using mixed solutions of glycerol and water at different concentrations, the relative humidity of a sealed container was adjusted to 50%, 60%, 70%, 80%, 90%, and 99% at room temperature (25°C). An aerogel membrane was placed in these solutions until it reached hygroscopic saturation, and then the TENG electrical performance was tested. The aerogel membrane TENG devices treated at different relative humidities were placed in a sealed container, and the relative humidity of the sealed container was adjusted to 50%, 60%, 70%, 80%, 90%, and 99% using a humidifier. After the relative humidity stabilized, the aerogel membrane triboelectric material prepared in Example 3 was cut into 2 cm × 2 cm squares and attached to an acrylic plate with conductive adhesive as the positive electrode material. A fluorinated ethylene propylene copolymer (FEP) film of the same size was cut as the negative electrode material and also attached to an acrylic plate with conductive adhesive. The positive and negative electrode plates were mounted on a sealed TENG electrical test bench, forming a vertical-contact separation mode TENG. Testing was performed at a frequency of 2 Hz, and the test results are as follows. Figure 13 As shown.

[0075] Depend on Figure 13 It is known that after the aerogel film triboelectric material undergoes moisture absorption treatment, the voltage of the material is 101.3 V at a relative humidity of 50%. As the relative humidity increases, the voltage slowly increases, reaching 155.1 V at extremely high relative humidity (99% RH), an increase of 153.1% compared to the normal relative humidity (50% RH). This is because in extremely high humidity environments, there are a large number of water molecules, and when the material reaches moisture saturation, it becomes hydrophilic. Water molecules combine with hydroxyl groups on the material's surface and inside to form hydrogen bonds, participating in friction and thus increasing the voltage.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing aerogel film triboelectric materials suitable for use in all humidity environments, characterized in that, Includes the following steps: (1) Take chitosan and polyvinyl alcohol solution and dissolve them in water. Mix them evenly after mechanical stirring. Then add acetic acid, sonicate, and let stand to obtain a mixed solution. The mass ratio of chitosan to polyvinyl alcohol solution, water, and acetic acid is 2 g : 4–10 mL : 85–95 mL : 1–2 mL; the mass percentage of the polyvinyl alcohol solution is 8–10 wt%. (2) The mixed solution is introduced into a mold for directional freezing to obtain a frozen block gel; The directional freezing uses anhydrous ethanol as the cold source. The bottom of the mold is in contact with and parallel to the surface of the anhydrous ethanol liquid. The temperature gradient is -80 to 25°C. The mold sinks 1 cm every 0.5 h and is frozen for 2 to 2.5 h. (3) The block gel is placed in a refrigerator for low-temperature storage, and then freeze-dried to obtain the aerogel material; (4) The aerogel material is cold-pressed using a flat vulcanizing machine and then dried in an oven to obtain an aerogel film triboelectric material suitable for all humidity environments.

2. The method for preparing aerogel film triboelectric material suitable for all humidity environments according to claim 1, characterized in that, In step (1), the mechanical stirring speed is 300-400 rpm and the time is 4-5 h; the ultrasonic treatment time is 8-10 min.

3. The method for preparing aerogel film triboelectric material suitable for all humidity environments according to claim 1, characterized in that, In step (2), the mold is a rectangular open container with a heat-conducting bottom and heat-insulating sides, with dimensions of (5~10)cm×(0.5~1)cm×(5~10)cm. The container is made of acrylic material around its sides, wrapped with heat-insulating cotton, and sealed with glass sheets at the bottom.

4. The method for preparing aerogel film triboelectric material suitable for all humidity environments according to claim 1, characterized in that, In step (3), the low-temperature preservation temperature is -20 to -22°C, and the time is 0.5 to 1 h.

5. The method for preparing aerogel film triboelectric material suitable for all humidity environments according to claim 1, characterized in that, In step (3), the vacuum degree of the freeze drying is 15 to 20 Pa, the temperature is -70 to -80°C, and the time is 45 to 48 h.

6. The method for preparing aerogel film triboelectric material suitable for all humidity environments according to claim 1, characterized in that, In step (4), the pressure of the cold pressing is 0.8 to 1.2 MPa, the temperature is 24 to 26°C, and the time is 1 to 2 min; the compression direction of the aerogel material is parallel to the direction of ice crystal growth.

7. The method for preparing aerogel film triboelectric material suitable for all humidity environments according to claim 1, characterized in that, In step (4), the drying temperature in the oven is 45-50°C and the drying time is 22-24 h.

8. An aerogel film triboelectric material suitable for all humidity environments, prepared by the preparation method of the aerogel film triboelectric material suitable for all humidity environments as described in any one of claims 1-7.

Images