Wide-temperature-range anti-freezing water-retaining type moisture power generator and preparation method thereof

Abstract

This invention discloses a wide-temperature-range freeze-resistant and water-retaining humidifier and its preparation method. The generator includes: a bottom electrode layer; a freeze-resistant and moisture-absorbing ionogel layer loaded on the bottom electrode layer, formed by fixing functionalized ionic liquid in a hydrophilic polymer network through in-situ polymerization or physical blending; a hydrophobic and breathable top layer with radiative cooling function, covering the ionogel layer and forming an adhesive layer; and a top electrode electrically connected to the ionogel layer. This invention passively cools and suppresses moisture evaporation at high temperatures through a top-layer radiative cooling porous membrane, while its hydrophobic and breathable porous structure addresses the dual requirements of "high-temperature water retention" and "open-type moisture absorption"; the ionic liquid lowers the freezing point of the gel layer to below -30°C, achieving low-temperature freeze resistance. The synergistic effect of the three layers enables the generator to stably output power within a wide temperature range of -30°C to 60°C, making it suitable for self-powered systems in extreme environments.

Description

Technical Field

[0001] This invention relates to the technical field of wet generator manufacturing, and more particularly to a wide-temperature-range antifreeze and water-retaining wet generator and its manufacturing method. Background Technology

[0002] With the explosive growth of the Internet of Things and wearable electronic devices, the development of sustainable self-powered technologies has become a key focus of international attention. Among numerous environmental energy harvesting technologies, wet energy generation, as an emerging green energy harvesting method, converts environmental heat energy into electrical energy through the interaction of functional materials and water molecules, offering advantages such as being green, environmentally friendly, and continuously available.

[0003] However, existing wet power generation devices face severe environmental adaptability challenges in practical outdoor applications: (1) Low temperature failure: In sub-zero environments, water molecules, which serve as charge transport media, freeze, leading to blockage of ion channels, infinite internal resistance of the device, and a basic loss of power generation function. (2) High temperature drying: In high temperature or direct sunlight environments, the water adsorbed inside the device evaporates and dissipates rapidly, causing the electrolyte layer to crack and the output performance to drop sharply.

[0004] To address the aforementioned issues, existing technologies typically employ physical encapsulation (which hinders moisture adsorption) or the addition of a single antifreeze agent (which fails to solve the problem of high-temperature evaporation). However, while physical encapsulation can suppress moisture evaporation to some extent, the encapsulation layer simultaneously blocks the continuous diffusion of ambient moisture into the device, disrupting the "open-type moisture absorption" channel necessary for moisture power generation, leading to a technical dilemma of "water retention requires sealing, but sealing makes absorption difficult." On the other hand, while adding a single antifreeze agent can lower the freezing point, it cannot solve the problem of rapid moisture evaporation in high-temperature environments, and the addition of antifreeze agents often affects the intrinsic moisture absorption properties of the material, resulting in another dilemma of "antifreeze but not water retention." Therefore, existing technologies struggle to simultaneously achieve "open-type moisture absorption" and "wide-temperature range stability," necessitating the development of a novel device structure that integrates thermal management, antifreeze, and moisture-absorbing power generation. Summary of the Invention

[0005] This application provides a wide-temperature-range antifreeze and water-retaining wet generator and its manufacturing method. Through biomimetic structural design and the synergistic effect of functional materials, it can achieve stable and continuous power output in a wide temperature range from -30℃ to 60℃.

[0006] A wide-temperature-range antifreeze and water-retaining wet generator, characterized in that it comprises:

[0007] Bottom electrode layer;

[0008] An antifreeze-hygroscopic ionic gel layer is loaded on the bottom electrode layer. The antifreeze-hygroscopic ionic gel layer is formed by immobilizing functionalized ionic liquid in a hydrophilic polymer network through in-situ polymerization or physical blending.

[0009] A hydrophobic and breathable top layer with radiative cooling function covers the antifreeze and moisture-absorbing ionogel layer and forms a bond;

[0010] The top electrode is electrically connected to the antifreeze and moisture-absorbing ionogel layer.

[0011] Preferably, the ionic liquid is selected from one or more of choline bis(trifluoromethanesulfonyl)imine salt, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium acetate, and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt; and the polymer is one or more of polyacrylamide, polyvinyl alcohol, polyacrylic acid, or copolymers thereof.

[0012] Preferably, the hydrophobic and breathable top layer is a polymer with high infrared emissivity in the 8-13μm band of the atmospheric window, which is used as the substrate and is prepared as a nanofiber porous film by electrospinning.

[0013] Preferably, the polymer substrate is selected from one or more of cellulose acetate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, and polylactic acid.

[0014] Preferably, the polymer substrate is cellulose acetate, polyvinylidene fluoride-hexafluoropropylene, or polyvinylidene fluoride; the functionalized ionic liquid is choline bis(trifluoromethanesulfonyl)imine salt, 1-ethyl-3-methylimidazolium tetrafluoroborate, or 1-butyl-3-methylimidazolium chloride; and the polymer is polyacrylamide, polyvinyl alcohol, or polyacrylic acid.

[0015] Preferably, the substrate is polyvinylidene fluoride, and the nanofiber porous film is also doped with an infrared emission enhancing filler, wherein the infrared emission enhancing filler is barium sulfate nanoparticles.

[0016] This invention also provides a method for preparing any of the above-mentioned wide-temperature-range antifreeze and water-retaining wet generators, comprising the following steps:

[0017] Step 1: Preparation of a hydrophobic and breathable top layer with radiative cooling function

[0018] Step 2: Preparation of the antifreeze and moisture-absorbing ionogel layer

[0019] Specific ionic liquids are immobilized in a hydrophilic polymer network through in-situ polymerization or physical blending to form an antifreeze and moisture-absorbing ionic gel layer.

[0020] Step 3: Generator Assembly

[0021] The antifreeze-hygroscopic ionogel layer prepared in step two is loaded onto the surface of the bottom electrode layer. Then, the hydrophobic and breathable top layer with radiation cooling function prepared in step one is covered on the surface of the antifreeze-hygroscopic ionogel layer, and a top electrode is configured to construct a sandwich structure of "substrate-gel-porous film".

[0022] One technical solution provided in this application embodiment has at least the following technical effects:

[0023] 1. This invention creatively combines passive radiative cooling with an ionic liquid antifreeze mechanism, and innovatively employs a hydrophobic and breathable porous membrane as the top layer structure. This top layer passively cools the water at high temperatures and inhibits moisture evaporation through radiative cooling, while retaining micro- and nano-pores as water vapor diffusion channels. It perfectly balances the dual requirements of "high-temperature water retention" and "open-type moisture absorption," breaking through the technical bottleneck of traditional technology where "water retention requires sealing, and sealing makes absorption difficult." The synergistic effect of the three layers enables the generator to maintain stable power output within a wide temperature range of -30℃ to 60℃.

[0024] 2. The top layer of the generator of the present invention is made of nanofiber porous membrane prepared by electrospinning, which has both hydrophobicity and air permeability. The hydrophobic design can effectively block the scouring of external liquid water and prevent electrolyte loss; the micro-nano pores serve as open moisture diffusion channels, ensuring that water vapor channels enter the gel layer, maintaining the generator's "breathing" function and continuous power generation capability.

[0025] 3. The functionalized ionic liquid (especially hydroxyl-containing cations) used in the generator of this invention not only has an antifreeze effect, but its rich polar groups can also significantly enhance the ability to capture moisture in the air, thereby improving the power generation efficiency in low humidity environments.

[0026] 4. The technical solution in Embodiment 3 of this invention further enhances the radiative cooling effect by doping the top polymer substrate with infrared emission-enhancing filler. The synergistic effect of the two enhances the infrared emissivity and solar reflectivity of the thin film in the atmospheric window band, providing an optional optimization solution for high-performance application scenarios. Attached Figure Description

[0027] Figure 1 A represents the microstructure of the top-layer radiation-cooling thin film prepared in Example 1 of this invention; Figure 1 B represents the microstructure of the intermediate ion gel prepared in Example 1 of this invention;

[0028] Figure 2 The contact angle of the top-layer radiation-cooling thin film prepared in Embodiment 1 of the present invention;

[0029] Figure 3The DSC curves are of the intermediate ionic gel and the pure hydrogel without ionic liquid prepared in Example 1 of the present invention.

[0030] Figure 4 The electrical output performance curves of the power generation device prepared in Embodiment 1 of the present invention under cyclic testing in a wide temperature range (e.g., -30 ℃, 20 ℃, 60 ℃). Detailed Implementation

[0031] The technical solution in this application is to solve the above problems, and the overall approach is as follows:

[0032] By constructing a three-layered moisture generator, radiative cooling, antifreeze and water retention, and moisture power generation are integrated into one unit. The top layer utilizes a nanofiber porous membrane prepared by electrospinning to achieve passive radiative cooling, reducing the device's operating temperature to suppress moisture evaporation. Simultaneously, this nanofiber porous membrane possesses hydrophobic and breathable properties—the hydrophobicity prevents the intrusion of external liquid water, while the micron-sized pores provide open diffusion channels for ambient moisture, ensuring the middle layer can continuously capture moisture, overcoming the technical contradiction of traditional encapsulation technology: "water retention requires sealing, sealing makes absorption difficult." The middle layer introduces functionalized ionic liquids into a hydrophilic polymer network, enhancing moisture capture capabilities while imparting antifreeze properties to the material. The bottom conductive substrate serves as a channel for charge collection and transport. The synergistic effect of the three layers solves the technical problem of performance degradation in existing moisture generators under extreme temperatures. The following detailed embodiments illustrate the technical solution of this invention.

[0033] To better understand the above technical solution, the following will provide a detailed explanation of the above technical solution using specific implementation methods.

[0034] Example 1

[0035] This embodiment provides a wide-temperature-range freeze-resistant and water-retaining wet gas generator and its preparation method, the specific steps of which are as follows:

[0036] Step 1: Preparation of a hydrophobic and breathable top layer with radiative cooling function

[0037] Cellulose acetate (CA) with an acetyl content of 39.8% was used as the base material and dissolved in a mixed solvent of acetone and dimethylacetamide (DMAc) at a volume ratio of 2:1. The solution was stirred at room temperature for 12 hours to prepare a 15 wt% spinning precursor solution. The spinning precursor solution was injected into a syringe, and spinning was performed using an electrospinning machine.

[0038] The spinning process parameters were set as follows: applied voltage 20 kV, needle-to-receiving plate distance 15 cm, feed rate 1.0 mL / h, and ambient humidity controlled below 40%. A white cellulose acetate (CA) nanofiber membrane with a thickness of approximately 50 μm was collected on an aluminum foil substrate.

[0039] Tests showed that the CA nanofiber membrane prepared in this embodiment had an average reflectance of >85% in the solar spectrum band (0.3-2.5μm) and an average infrared emissivity of >92% in the atmospheric window band (8-13μm).

[0040] Step 2: Preparation of the antifreeze and moisture-absorbing ionogel layer

[0041] First, choline bis(trifluoromethanesulfonyl)imine salt ionic liquid was synthesized by ion exchange. Then, 5 g of ionic liquid was taken, and 2 g of acrylamide AAM monomer, 0.01 g of N,N'-methylenebisacrylamide MBA and 0.05 g of ammonium persulfate APS were added. The mixture was stirred evenly and ultrasonically defoamed to obtain a clear precursor solution.

[0042] The precursor solution was injected into a glass mold with a thickness of 1 mm and irradiated under a 365 nm, 10 W UV lamp for 10 minutes. Through in-situ polymerization, a transparent, soft and highly adhesive antifreeze and hygroscopic ionogel was obtained.

[0043] Step 3: Generator Assembly

[0044] (1) Cut a hydrophilic carbon cloth with a size of 2 cm × 2 cm as the bottom electrode layer.

[0045] (2) The ion gel layer prepared in step two is laid flat on the bottom electrode. Then, the cellulose acetate CA nanofiber membrane prepared in step one is covered on the upper surface of the antifreeze and moisture-absorbing ion gel layer, and the gel itself is used to achieve a tight fit.

[0046] (3) A copper tape is drawn out from one side of the antifreeze and moisture-absorbing ion gel layer as the top electrode to obtain the target generator.

[0047] Step 4 Performance Verification

[0048] The target generator was placed in a -20°C environment, and it remained flexible with no internal ice crystal formation, maintaining an open-circuit voltage above 0.9 V. Under simulated sunlight (1 kW / m²), the generator also performed well. 2 At an ambient temperature of 30°C, due to the radiative cooling effect of the top CA film, the device surface temperature is about 10°C lower than the ambient temperature, and after 24 hours of continuous operation, the voltage retention rate is 96% of the initial value, demonstrating excellent wide-temperature stability.

[0049] Example 2

[0050] This embodiment provides a wide-temperature-range humid gas generator based on an electrospun PVDF-HFP and physically cross-linked PVA system. The specific steps are as follows:

[0051] Step 1: Preparation of a hydrophobic and breathable top layer with radiative cooling function

[0052] Weigh out polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) powder and dissolve it in a mixed solvent of acetone and N,N-dimethylformamide (DMF) at a volume ratio of 3:2 to prepare a spinning solution with a concentration of 18 wt%. Place the spinning solution in an injection pump and prepare the solution using electrospinning.

[0053] The spinning process parameters were set as follows: voltage 18 kV, receiving distance 18 cm, and feed rate 0.8 mL / h. A hydrophobic nanofiber membrane with a thickness of approximately 60 μm was collected on the roller receiver. This membrane is composed of interlaced nanofibers stacked together, has a micro-nanoporous structure, a porosity >80%, and exhibits excellent air permeability and hydrophobicity.

[0054] Step 2: Preparation of Physically Crosslinked Antifreeze Gel

[0055] Polyvinyl alcohol (PVA-1799) was dissolved in deionized water to prepare a 10 wt% solution. After cooling to 60°C, 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid was added, maintaining a PVA to ionic liquid mass ratio of 1:1, and the mixture was thoroughly mixed. The mixture was poured into a mold and frozen at -20°C for 12 hours, then thawed at room temperature for 6 hours. This cycle was repeated three times to obtain a high-strength antifreeze gel through physical microcrystalline crosslinking.

[0056] Step 3: Generator Assembly

[0057] A generator was fabricated by using conductive carbon nanotube paper as the bottom electrode layer, loading the PVA-based antifreeze gel prepared in step two, covering the surface with a polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) nanofiber membrane prepared in step one, and then leading wires out between the layers to complete the assembly.

[0058] Step 4 Performance Verification

[0059] Tests showed that the generator's internal resistance change rate was less than 15% at -20℃. At 50℃, due to the radiative cooling effect and physical barrier effect of the PVDF-HFP top layer, the moisture retention rate of the generator in this embodiment was significantly better than that of the control generator without a top layer cover.

[0060] Example 3

[0061] This embodiment provides a composite wide-temperature-range humid gas generator based on functional particle doping and electrospinning technology. The specific steps are as follows:

[0062] Step 1: Preparation of the composite radiation cooling layer

[0063] Polyvinylidene fluoride (PVDF) was selected as the polymer matrix, and barium sulfate (BaSO4) nanoparticles (approximately 200 nm in diameter) were used as infrared emission enhancement fillers.

[0064] First, BaSO4 was ultrasonically dispersed in a DMF / acetone mixed solvent for 2 hours. Then, polyvinylidene fluoride (PVDF) powder was added and stirred to dissolve, preparing a spinning precursor solution with a PVDF concentration of 16 wt% and a BaSO4 doping amount of 20% of the PVDF mass. Electrospinning was then performed using the following parameters: voltage 22 kV, receiving distance 15 cm.

[0065] Due to the doping of BaSO4 particles, the surface of the nanofibers obtained by electrospinning has a higher roughness, and the phonon polarization resonance of BaSO4 and the Mie scattering of nanofibers work synergistically to further enhance the emissivity of the film in the atmospheric window band and the reflectivity of sunlight.

[0066] Step 2: Preparation of the antifreeze and moisture-absorbing ionogel layer

[0067] Using AA acrylic acid as the monomer, a 1-butyl-3-methylimidazolium chloride ionic liquid was added. This ionic liquid has strong hygroscopic properties, which is beneficial for applications in low-humidity environments. A highly hygroscopic ionic gel was prepared by thermally initiated in-situ polymerization at 60°C for 4 hours in the presence of crosslinking agent MBA and initiator APS.

[0068] Step 3: Generator Assembly

[0069] A generator is fabricated by aligning and stacking the composite nanofiber membrane prepared in step one, the ionogel layer prepared in step two, and the bottom flexible conductive fabric, such as nickel-plated copper cloth, using a lamination process.

[0070] Step 4 Performance Verification

[0071] The generator combines the high hygroscopicity of ionic liquids with the super-strong radiative cooling capacity of PVDF / BaSO4 composite nanofibers.

[0072] In outdoor testing (ambient humidity 40% RH, light intensity 1 kW / m²), 2 The generator surface temperature in this embodiment is 6-8°C lower than the ambient temperature, and it can still maintain a high short-circuit current output at night or under low humidity conditions, which proves the synergistic effect of the specific ionic liquid and the doped modified electrospun film.

[0073] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0074] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A wide-temperature-range antifreeze and water-retaining wet gas generator, characterized in that, include: Bottom electrode layer; An antifreeze-hygroscopic ionic gel layer is loaded on the bottom electrode layer. The antifreeze-hygroscopic ionic gel layer is formed by immobilizing functionalized ionic liquid in a hydrophilic polymer network through in-situ polymerization or physical blending. A hydrophobic and breathable top layer with radiative cooling function covers the antifreeze and moisture-absorbing ionogel layer and forms a bond; The top electrode is electrically connected to the antifreeze and moisture-absorbing ionogel layer.

2. The wide-temperature-range antifreeze and water-retaining wet generator as described in claim 1, characterized in that, The ionic liquid is selected from one or more of choline bis(trifluoromethanesulfonyl)imine salt, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium acetate, and 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imine salt; the polymer is one or more of polyacrylamide, polyvinyl alcohol, polyacrylic acid, or copolymers thereof.

3. The wide-temperature-range antifreeze and water-retaining wet gas generator as described in claim 1, characterized in that, The hydrophobic and breathable top layer is made of a polymer with high infrared emissivity in the atmospheric window 8-13μm band as the substrate, and nanofiber porous film is prepared by electrospinning process.

4. The wide-temperature-range antifreeze and water-retaining wet generator as described in claim 3, characterized in that, The polymer substrate is selected from one or more of cellulose acetate, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, and polylactic acid.

5. The wide-temperature-range antifreeze and water-retaining wet gas generator as described in claim 3, characterized in that, The polymer substrate is cellulose acetate, polyvinylidene fluoride-hexafluoropropylene, or polyvinylidene fluoride; the functionalized ionic liquid is choline bis(trifluoromethanesulfonyl)imine salt, 1-ethyl-3-methylimidazolium tetrafluoroborate, or 1-butyl-3-methylimidazolium chloride; and the polymer is polyacrylamide, polyvinyl alcohol, or polyacrylic acid.

6. The wide-temperature-range antifreeze and water-retaining wet gas generator as described in claim 5, characterized in that, The substrate is polyvinylidene fluoride, and the nanofiber porous film is also doped with infrared emission enhancing filler, wherein the infrared emission enhancing filler is barium sulfate nanoparticles.

7. The method for preparing a wide-temperature-range antifreeze and water-retaining wet generator as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Preparation of a hydrophobic and breathable top layer with radiative cooling function Step 2: Preparation of the antifreeze and moisture-absorbing ionogel layer Specific ionic liquids are immobilized in a hydrophilic polymer network through in-situ polymerization or physical blending to form an antifreeze and moisture-absorbing ionic gel layer. Step 3: Generator Assembly The antifreeze-hygroscopic ionogel layer prepared in step two is loaded onto the surface of the bottom electrode layer. Then, the hydrophobic and breathable top layer with radiation cooling function prepared in step one is covered on the surface of the antifreeze-hygroscopic ionogel layer, and a top electrode is configured to construct a sandwich structure of "substrate-gel-porous film".

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