A radiant cooling device and a method for manufacturing the same

Abstract

The present invention provides a radiation cooling device and a preparation method thereof. The method comprises: providing two transparent conductive glasses, etching a plurality of micro-cone structures on the non-conductive surface of one of the transparent conductive glasses, forming a frame around the other transparent conductive glass using insulating gaskets, covering the transparent conductive glass with the micro-cone structures on top of the frame to obtain a hollow structure, injecting an electrolyte into the hollow structure, and sealing the hollow structure on all sides to obtain a radiation cooling device; applying a voltage to the radiation cooling device, so that metal ions in the electrolyte can be deposited on the conductive surface of the transparent conductive glass with the micro-cone structures etched thereon, and the combined effect of the micro-cone structures on the non-conductive surface of the transparent conductive glass enables the radiation cooling device to have both high emissivity in the mid-infrared band and high reflectivity in the visible light band, thereby ensuring that the radiation cooling device has an excellent radiation cooling effect and dynamic adjustment of the cooling effect.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation refrigeration, and in particular to a radiation refrigeration device and a preparation method thereof. Background Art

[0002] In recent years, the dramatic increase in energy consumption has led to excessive greenhouse gas emissions, disrupting the climate balance and causing global warming and frequent extreme weather events. Simultaneously, the annual energy consumption for building cooling has also increased dramatically. Currently, cooling is typically achieved through convection and conduction. However, these cooling methods not only have drawbacks such as high energy consumption and pollution, but also exacerbate the urban heat island effect, creating a vicious cycle.

[0003] Radiative cooling materials achieve efficient radiative heat exchange by radiating their own heat to a cold source in space in the form of electromagnetic waves. By using radiative cooling materials, a cooling effect can be achieved without consuming additional energy, thereby reducing the consumption of cooling energy. Since the heat radiated from buildings under summer temperature conditions is mainly concentrated in the mid-infrared band, in order to achieve a better cooling effect, radiative cooling materials are generally required to have a high emissivity in the mid-infrared band and a high reflectivity in the visible light band. However, current radiative cooling materials have poor cooling effects and cannot achieve dynamic adjustment of the cooling effect; therefore, based on the above problems, it is necessary to provide a radiative cooling device with good cooling effect and dynamically adjustable cooling effect and a preparation method thereof. Summary of the Invention

[0004] An embodiment of the present invention provides a radiative cooling device and a preparation method thereof. The radiative cooling device has the advantages of excellent radiative cooling effect and dynamically adjustable cooling effect.

[0005] In a first aspect, the present invention provides a method for preparing a radiative cooling device, the method comprising the following steps:

[0006] (1) Providing a first transparent conductive glass and a second transparent conductive glass; wherein the first transparent conductive glass and the second transparent conductive glass each include a conductive surface and a non-conductive surface opposite to each other in a thickness direction;

[0007] (2) etching a plurality of micro-cone structures on the non-conductive surface of the first transparent conductive glass;

[0008] (3) Using insulating spacers to form a frame around the second transparent conductive glass, and covering the first transparent conductive glass etched with a micro-cone structure on top of the frame to obtain a hollow structure; wherein the conductive surface of the second transparent conductive glass is arranged opposite to the conductive surface of the first transparent conductive glass;

[0009] (4) injecting an electrolyte into the hollow structure and sealing the four sides of the hollow structure to obtain the radiant cooling device;

[0010] The non-conductive surface of the first transparent conductive glass etched with the micro-cone structure is connected to the negative electrode of the power supply, and the non-conductive surface of the second transparent conductive glass is connected to the positive electrode of the power supply. After voltage is applied, dynamic adjustment of the cooling effect of the radiation refrigerator is achieved.

[0011] Preferably, in step (2), the micro-cone structure is obtained by etching through the following steps:

[0012] (21) soaking the non-conductive surface of the first transparent conductive glass in a hydrophilic solution and a sodium dodecylsulfate aqueous solution in sequence to obtain a hydrophilic first transparent conductive glass;

[0013] (22) adding a polystyrene emulsion dropwise onto the non-conductive surface of the hydrophilic first transparent conductive glass to obtain a single-layer polystyrene spherical film;

[0014] (23) Reactive ion etching is performed on the single-layer polystyrene spherical film to obtain the micro-cone structure.

[0015] Preferably, in step (21): the hydrophilic solution is a mixed solution of ammonia water and hydrogen peroxide; wherein the mass concentration of the ammonia water is 22-28%, and the mass concentration of the hydrogen peroxide is 28-32%;

[0016] The volume ratio of the ammonia solution to the hydrogen peroxide solution is (1-100):(1-100);

[0017] The mass concentration of the sodium dodecylsulfate aqueous solution is 5-20%.

[0018] Preferably, in step (22): the solvent of the polystyrene emulsion is a mixed solvent of anhydrous ethanol and water; wherein the volume ratio of the anhydrous ethanol to water is (1-100):(1-100);

[0019] The mass concentration of the polystyrene emulsion is 1 to 50%.

[0020] Preferably, in step (23), the reactive ion etching gas is trifluoromethane and oxygen; wherein the flow ratio of trifluoromethane to oxygen is (20-50): (0-20);

[0021] The time of the reactive ion etching is 1 to 100 minutes, and the power of the etcher is 1 to 500W.

[0022] Preferably, the micro-cone structures are arranged in an array on the non-conductive surface; and the height of each micro-cone structure is 1-2 μm.

[0023] Preferably, in step (3): the insulating gasket is polyimide or polytetrafluoroethylene;

[0024] The insulating gasket has a width of 30 to 35 mm and a thickness of 0.2 to 0.6 mm.

[0025] Preferably, in step (4): the electrolyte is prepared by dissolving silver nitrate, tetrabutylammonium bromide, copper chloride and polyvinyl butyral in dimethyl sulfoxide.

[0026] Preferably, in the electrolyte, the concentration of silver nitrate is 0.1-100 mmol / L, the concentration of tetrabutylammonium bromide is 1-1000 mmol / L, the concentration of copper chloride is 0.1-100 mmol / L, and the mass concentration of polyvinyl butyral is 8-12%.

[0027] Preferably, in step (4), a negative pressure of -2 to -3 V is applied to the radiant cooling device to achieve deposition of the silver film, and a positive pressure of 0.5 to 1 V is applied to dissolve the silver film.

[0028] In a second aspect, the present invention provides a radiative cooling device, which is prepared using any of the preparation methods described in the first aspect.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] In the present invention, two transparent conductive glasses are first provided, and a plurality of micro-cone structures are etched on the non-conductive surface of one of the transparent conductive glasses. Then, the conductive surfaces of the two transparent conductive glasses are arranged relative to each other using an insulating gasket to form a hollow structure. An electrolyte is injected into the hollow structure to seal it, thereby obtaining a radiative cooling device. When a negative voltage is applied to the radiative cooling device, metal ions in the electrolyte can be deposited on the conductive surface of the transparent conductive glass on which the micro-cone structure is etched to form a metal film. Combined with the combined effect of the micro-cone structures on the non-conductive surface of the transparent conductive glass, the radiative cooling device can have both high emissivity in the mid-infrared band and high reflectivity in the visible light band, thereby ensuring that the radiative cooling device has an excellent radiative cooling effect. Moreover, by changing the magnitude of the voltage applied to the radiative cooling device, the optical state of the radiative cooling device can be dynamically adjusted, thereby achieving dynamic adjustment of the cooling effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is a schematic structural diagram of a radiative cooling device provided by the present invention when no voltage is applied;

[0033] Figure 2 This is a schematic structural diagram of a radiative cooling device provided by the present invention after negative pressure is applied;

[0034] In the figure, 100 is a first transparent conductive glass; 200 is a second transparent conductive glass; 300 is an insulating spacer; 400 is an electrolyte; 102 is a micro-cone structure; and 500 is a silver mirror. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] Silicon dioxide is an ideal infrared radiation material, offering good spatial stability and no absorption in the solar wavelength range. However, due to the phonon-polariton resonance effect, its emissivity is low in the 8-14μm infrared atmospheric window. Under high temperatures, heat radiated from buildings is primarily concentrated in the mid-infrared band. Therefore, to achieve optimal cooling, radiative cooling materials are generally required to have both high emissivity in the mid-infrared band and high reflectivity in the visible light band. However, current radiative cooling materials only achieve high emissivity in the mid-infrared band, and cannot simultaneously achieve high reflectivity in the visible light band, resulting in poor cooling performance and the inability to dynamically adjust the cooling effect.

[0037] In view of the above problems, the present invention provides a method for preparing a radiative cooling device, which comprises the following steps:

[0038] (1) Providing a first transparent conductive glass and a second transparent conductive glass; wherein the first transparent conductive glass and the second transparent conductive glass each include a conductive surface and a non-conductive surface opposite to each other in a thickness direction;

[0039] (2) etching a plurality of micro-cone structures on the non-conductive surface of the first transparent conductive glass;

[0040] (3) Using insulating spacers to form a frame around the second transparent conductive glass, and covering the first transparent conductive glass etched with a micro-cone structure on top of the frame to obtain a hollow structure; wherein the conductive surface of the second transparent conductive glass is arranged opposite to the conductive surface of the first transparent conductive glass;

[0041] (4) injecting an electrolyte into the hollow structure and sealing the four sides of the hollow structure to obtain the radiant cooling device;

[0042] The non-conductive surface of the first transparent conductive glass etched with the micro-cone structure is connected to the negative electrode of the power supply, and the non-conductive surface of the second transparent conductive glass is connected to the positive electrode of the power supply. After voltage is applied, dynamic adjustment of the cooling effect of the radiant cooling device is achieved.

[0043] In the present invention, two transparent conductive glasses are first provided, and a plurality of micro-cone structures are etched on the non-conductive surface of one of the transparent conductive glasses. Then, the conductive surfaces of the two transparent conductive glasses are arranged relative to each other using an insulating spacer to form a hollow structure. An electrolyte is injected into the hollow structure to seal it, thereby obtaining a radiative cooling device. When different voltages are applied to the radiative cooling device, metal ions in the electrolyte can be deposited on the conductive surface of the transparent conductive glass etched with the micro-cone structure to form a silver film. Combined with the combined effect of the micro-cone structures on the non-conductive surface of the transparent conductive glass, the radiative cooling device can have both high emissivity in the mid-infrared band and high reflectivity in the visible light band, thereby ensuring that the radiative cooling device has an excellent radiative cooling effect. Moreover, by changing the magnitude of the voltage applied to the radiative cooling device, the optical state of the radiative cooling device can be dynamically adjusted, thereby achieving dynamic adjustment of the cooling effect.

[0044] It should be noted that the first transparent conductive glass and the second transparent conductive glass in the present invention are both ITO transparent conductive glass.

[0045] According to some preferred embodiments, in step (2): the micro-cone structure is obtained by etching through the following steps:

[0046] (21) soaking the non-conductive surface of the first transparent conductive glass in a hydrophilic solution and a sodium dodecylsulfate aqueous solution in sequence to obtain a hydrophilic first transparent conductive glass;

[0047] (22) adding a polystyrene emulsion dropwise onto the non-conductive surface of the hydrophilic first transparent conductive glass to obtain a single-layer polystyrene spherical film;

[0048] (23) Reactive ion etching is performed on the single-layer polystyrene spherical film to obtain the micro-cone structure.

[0049] In the present invention, before soaking the first transparent conductive glass, the first transparent conductive glass can be pretreated to remove impurities on its surface. During the pretreatment, the glass can be ultrasonically cleaned sequentially using deionized water, detergent, 99% acetone, and 75% ethanol, each ultrasonic cleaning lasting 10 to 20 minutes. The glass is then blown dry with nitrogen to obtain a clean first transparent conductive glass. The cleaned first transparent conductive glass is then sequentially soaked in a hydrophilic solution and an aqueous sodium dodecylsulfate solution for 6 to 8 hours. The hydrophilic solution can increase the hydrophilicity of the surface of the first transparent conductive glass, while the aqueous sodium dodecylsulfate solution can enhance the surface tension of the first transparent conductive glass, reduce its surface energy, and promote the subsequent formation of a dense, ordered polystyrene sphere film on the surface of the first transparent conductive glass.

[0050] It should be noted that, to reduce the difficulty of experimental operation, in the present invention, the entire first transparent conductive glass can be immersed in the hydrophilic solution and the sodium dodecylsulfonate aqueous solution. Furthermore, after the sodium dodecylsulfonate aqueous solution is prepared, ultrasonic treatment is also performed to ensure more uniform mixing of the aqueous solution, each time for 1 to 30 minutes, repeated 1 to 10 times.

[0051] When etching the micro-cone structure, specifically, the first transparent conductive glass can be first placed in a watch glass filled with deionized water, with its non-conductive surface facing up and the deionized water covering the non-conductive surface, and the polystyrene emulsion is slowly dripped onto the surface of the deionized water. In order to ensure that a tight polystyrene single-layer spherical film is formed on the non-conductive surface of the first transparent conductive glass, a sodium dodecylsulfate aqueous solution with a mass concentration of 5-6% can be continued to be dripped when a large film appears in the watch glass. Thereafter, the first transparent conductive glass is slowly taken out of the watch glass. At this time, the polystyrene balls are transferred from the surface of the deionized water to the non-conductive surface of the first transparent conductive glass, and dried at room temperature (25°C) until there is no moisture on the surface, thereby forming a single-layer polystyrene spherical film on the non-conductive surface.

[0052] According to some preferred embodiments, in step (21), the hydrophilic solution is a mixed solution of ammonia water and hydrogen peroxide; wherein the mass concentration of the ammonia water is 22-28% (for example, 22%, 24%, 25%, 26% or 28%), and the mass concentration of the hydrogen peroxide is 28-32% (for example, 28%, 30% or 32%);

[0053] The volume ratio of the ammonia water and the hydrogen peroxide solution is (1-100):(1-100) (for example, it can be 1:1, 1:20, 1:50, 1:80, 1:100, 7:3, 10:3, 20:5, 50:10, 50:80, 50:100 or 100:1); in the present invention, it is preferably (5-15):(2-5) (for example, it can be 5:2, 7:3, 10:4, 12:4 or 15:5); the mass concentration of the sodium dodecylsulfate aqueous solution is 5-20% (for example, it can be 5%, 10%, 15% or 20%).

[0054] According to some preferred embodiments, in step (22): the solvent of the polystyrene emulsion is a mixed solvent of anhydrous ethanol and water; wherein the volume ratio of anhydrous ethanol to water is (1-100):(1-100) (for example, it can be 1:1, 1:20, 1:50, 1:80, 1:100, 10:3, 20:5, 50:10, 50:80, 50:100 or 100:1), and in the present invention, it is preferably (20-50):(10-30); the mass concentration of the polystyrene emulsion is 1-50% (for example, it can be 1%, 5%, 10%, 20%, 30%, 40% or 50%), and in the present invention, it is preferably 2-5% (for example, it can be 2%, 3%, 4% or 5%).

[0055] In the present invention, it is preferred to use a polystyrene emulsion with a mass concentration of 2 to 5%, which is more conducive to forming a single-layer polystyrene spherical film on the surface of the first transparent conductive glass. If the mass concentration of the polystyrene emulsion is too low, it is not conducive to the formation of a dense and ordered polystyrene spherical film. If the mass concentration of the polystyrene emulsion is too high, a multi-layer polystyrene spherical film will be formed, which is not conducive to the formation of a single-layer polystyrene spherical film and affects the etching structure.

[0056] According to some preferred embodiments, in step (23): the reactive ion etching gas is trifluoromethane and oxygen; wherein the flow ratio of trifluoromethane and oxygen is (20-50): (0-20) (for example, it can be 20:1, 20:5, 20:10, 20:20, 30:20, 30:10, 30:5, 30:1, 50:1, 50:10, 50:15, or 50:20), preferably (40~50): (5~10); the time of the reactive ion etching is 1~100min (for example, it can be 1min, 10min, 20min, 50min, 80min or 100min), and the power of the etcher is 1~500W (for example, it can be 1W, 10W, 20W, 50W, 100W, 200W, 300W, 400W or 500W), preferably 1~300W.

[0057] In some preferred embodiments, the micro-cone structures are all conical in shape, and each micro-cone structure is arranged in an array on the non-conductive surface; the height of the micro-cone structures is 1 to 2 μm (for example, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm or 2 μm).

[0058] In the present invention, reactive ion etching is used to etch a single layer of polystyrene sphere film on the surface of the first transparent conductive glass. By comprehensively controlling parameters such as the gas flow rate ratio, etching time, and etching power during the etching process, it is advantageous to form a plurality of conical micro-cone structures of the same size and arranged in an array on the surface of the first transparent conductive glass. The conical micro-cone structures have a high absorptivity in the infrared region, thereby significantly improving the emissivity of the first transparent conductive glass in the mid-infrared band and ensuring that the radiative cooling device has a good cooling effect. In the present invention, if the gas flow rate ratio, etching time, or etching power is too small, the height of the formed conical micro-cone structures will be small, which is not conducive to ensuring a good cooling effect of the radiative cooling device. If the gas flow rate ratio, etching time, or etching power are too high, the polystyrene spheres will be completely polished, unable to protect the structure of the transparent conductive glass at the bottom, resulting in a rough surface and a reduced depth, which is not conducive to enhancing the cooling effect of the radiative cooling device.

[0059] It should be noted that the etching power in the present invention specifically refers to the RF2 power of the etcher.

[0060] In some preferred embodiments, in step (3): the insulating gasket is polyimide or polytetrafluoroethylene; the width of the insulating gasket is 30 to 35 mm (for example, it can be 30 mm, 31 mm, 32 mm, 33 mm, 34 mm or 35 mm), and the thickness is 0.2 to 0.6 mm (for example, it can be 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm or 0.6 mm).

[0061] In the present invention, the second transparent conductive glass can be treated using the same method as the pretreatment of the first transparent conductive glass to remove impurities on the surface of the second transparent conductive glass, thereby obtaining a clean second transparent conductive glass. Subsequently, the conductive surface of the first transparent conductive glass, on which the non-conductive surface is etched with a conical micro-cone structure, and the conductive surface of the clean second transparent conductive glass are placed opposite each other and separated by an insulating spacer of a certain width and thickness. After an electrolyte is injected into the space between the two, the insulating spacer and the transparent conductive glass are finally sealed around the contact area using ultraviolet curing adhesive to obtain a radiant cooling device.

[0062] According to some preferred embodiments, in step (4): the electrolyte is prepared by dissolving silver nitrate, tetrabutylammonium bromide, copper chloride and polyvinyl butyral in dimethyl sulfoxide; in the electrolyte, the concentration of silver nitrate is 0.1 to 100 mmol / L (for example, 0.1 mmol / L, 0.5 mmol / L, 1 mmol / L, 5 mmol / L, 10 mmol / L, 20 mmol / L, 50 mmol / L, 80 mmol / L or 100 mmol / L), the concentration of tetrabutylammonium bromide is 1 to 1000 mmol / L (for example, 1 mmol / L, 5 mmol / L, 10 mmol / L, 20 mmol / L, 50 mmol / L, 80 mmol / L or 100 mmol / L), and the concentration of tetrabutylammonium bromide is 1 to 1000 mmol / L (for example, 1 mmol / L, 5 mmol / L, 10 mmol / L, 20 mmol / L, 50 mmol / L, 80 mmol / L or 100 mmol / L). mol / L, 50mmol / L, 100mmol / L, 300mmol / L, 500mmol / L, 800mmol / L or 1000mmol / L), copper chloride has a concentration of 0.1 to 100mmol / L (for example, it can be 0.1mmol / L, 0.5mmol / L, 1mmol / L, 5mmol / L, 10mmol / L, 20mmol / L, 50mmol / L, 80mmol / L or 100mmol / L), and the mass concentration of polyvinyl butyral is 8 to 12% (for example, it can be 8%, 9%, 10%, 11% or 12%).

[0063] In the present invention, a certain voltage is applied to the radiative cooling device. Under the action of the certain voltage, the silver nitrate and tetrabutylammonium bromide in the above-mentioned electrolyte will undergo redox reactions respectively. After the silver ions are reduced, they will become elemental silver. The elemental silver will be deposited on the conductive surface of the first transparent conductive glass, thereby causing the first transparent conductive glass to change from a transparent state to a silver mirror state. At this time, a synergistic effect occurs between the conical micro-cone structure on the non-conductive surface of the first transparent conductive glass and the silver mirror formed on the conductive surface, thereby further improving the cooling effect of the radiative cooling device. At the same time, a certain voltage is applied to the radiative cooling device again. At this time, the silver elemental silver adsorbed on the conductive surface of the first transparent conductive glass will be oxidized into silver ions, and the silver mirror state of the first transparent conductive glass will fade and return to its original transparent state, thereby achieving dynamic adjustment of the cooling effect of the radiative cooling device.

[0064] At the same time, it should be noted that in the electrolyte of the present invention, the concentration of silver nitrate is preferably 10-50 mmol / L, the concentration of tetrabutylammonium bromide is preferably 50-250 mmol / L, the concentration of copper chloride is preferably 1-10 mmol / L, and the mass concentration of polyvinyl butyral is preferably 8-12%. This is more conducive to achieving dynamic adjustment of the refrigeration effect of the radiant refrigeration device and is conducive to further improving the refrigeration effect of the radiant refrigeration device; if the concentration of silver nitrate and tetrabutylammonium bromide is too low, it is not conducive to further improving the refrigeration effect of the radiant refrigeration device; if the concentration of silver nitrate and tetrabutylammonium bromide is too high, silver bromide precipitation will be generated in the electrolyte, which is not conducive to the occurrence of redox reaction; by adding a certain amount of polyvinyl butyral to the electrolyte, it can ensure that the silver mirror is better formed on the non-conductive surface of the first transparent conductive glass, and the copper chloride in the electrolyte can accelerate the fading rate of the silver mirror in the later stage, thereby better achieving dynamic adjustment of the refrigeration effect of the radiant refrigeration device. At the same time, it should be noted that in the present invention, the concentration ratio of silver nitrate and tetrabutylammonium bromide is preferably 1: (3 to 7). More preferably, when the concentration ratio of silver nitrate and tetrabutylammonium bromide is 1: 5, the reflectivity of the silver mirror formed by the radiant cooling device is the highest, and the reflectivity in the light band can reach up to 80%.

[0065] According to some preferred embodiments, in step (4), after applying a negative pressure of -2 to -3 V (for example, -2.0 V, -2.5 V or -3 V) to the radiant cooling device, the silver film is deposited, and after applying a positive pressure of 0.5 to 1 V (for example, 0.5 V, 0.8 V or 1.0 V), the silver film is dissolved.

[0066] like Figure 1 and Figure 2As shown, the radiative cooling device prepared in the present invention can be converted between a transparent state and a silver mirror state. The non-conductive surface of a first transparent conductive glass having a micro-cone structure etched thereon is connected to the negative electrode of a power supply, and the non-conductive surface of a clean second transparent conductive glass is connected to the positive electrode of a power supply. Specifically, after applying a voltage of -2.0 to -3.0 V for 20 to 40 seconds, Ag+ is deposited on the conductive surface of the first transparent conductive glass having the micro-cone structure, achieving a mirror state. During the negative voltage application, if the voltage application time is too short, it will be detrimental to the formation of the Ag film, resulting in a low reflectivity. If the voltage application time is too long, the Ag film will be broken down, which will also have an adverse effect on the reflectivity. After applying a voltage of 0.5 to 1.0 V for 30 to 100 seconds, the silver film deposited on the conductive surface of the first transparent conductive glass having the micro-cone structure dissolves and fades, and the device returns to a transparent state from the silver mirror state. During the positive voltage application, if the voltage application time is too short, the Ag film will not fade away. Once the Ag film fades away, there is no need to continue applying the voltage. In the present invention, by changing the magnitude of the applied voltage, dynamic adjustment of different optical states of the radiation cooling device is achieved, which meets the adjustment of different cooling needs, thereby achieving the purpose of energy saving and emission reduction.

[0067] It should be noted that, in order to clearly represent the electrolyte, the present invention Figure 1 and Figure 2 In the figure, the insulating spacers are only shown on two sides of the second conductive glass. In practice, it should be understood that the insulating spacers are arranged around the second transparent conductive glass.

[0068] The present invention also provides a radiation cooling device, which is prepared by the preparation method provided by the present invention.

[0069] The present invention utilizes silver ions in an electrolyte to deposit and dissolve on the conductive surface of a first transparent conductive glass when different voltages are applied, thereby achieving the transition of the radiative cooling device from a transparent state to a silver mirror state. Since the non-conductive surface of the first transparent conductive glass has an array of conical structures and a silver mirror state on the conductive surface, the radiative cooling device can achieve high emissivity in the mid-infrared band and high reflectivity in the infrared band. By adjusting the voltage and time of the radiative cooling device, the radiative cooling device can regulate the reflectivity of the solar spectrum. Recently, the reflectivity in the range of 250nm to 2500nm can be adjusted, meeting the dynamic regulation of the radiative cooling device for different cooling effects.

[0070] In order to more clearly illustrate the technical solutions and advantages of the present invention, a radiative cooling device and a preparation method thereof are described in detail below through several embodiments.

[0071] Example 1:

[0072] (1) providing a first transparent conductive glass and a second transparent conductive glass; wherein the first transparent conductive glass and the second transparent conductive glass each include conductive surfaces and non-conductive surfaces opposite to each other in a thickness direction;

[0073] (2) etching a plurality of micro-cone structures on the non-conductive surface of the first transparent conductive glass; the micro-cone structures have a height of 2 μm, and the micro-cone structures are arranged in an array on the non-conductive surface;

[0074] (21) A hydrophilic solution is obtained by mixing ammonia water with a mass concentration of 25% and hydrogen peroxide with a mass concentration of 30% in a volume ratio of 10:3; after pretreating a first transparent conductive glass, the non-conductive surface of the first transparent conductive glass is immersed in the hydrophilic solution and a sodium dodecylsulfate aqueous solution with a mass concentration of 15% for 8 hours to obtain a hydrophilic first transparent conductive glass;

[0075] (22) Deionized water was added to a watch glass, and the first transparent conductive glass was placed in the watch glass with its non-conductive surface facing up. A 15% polystyrene emulsion (the solvent was anhydrous ethanol and water in a volume ratio of 1:1) was slowly added dropwise to the surface of the deionized water. When a large film appeared, a 5% sodium dodecylsulfate aqueous solution was added dropwise. The first transparent conductive glass was then slowly taken out. At this time, the polystyrene balls were transferred from the deionized water surface to the non-conductive surface of the first transparent conductive glass. The film was dried at room temperature (25°C) for 12 hours to obtain a single-layer polystyrene ball film.

[0076] (23) Reactive ion etching was performed on the surface of a single-layer polystyrene spherical film to obtain a micro-cone structure; wherein, the etching gas was trifluoromethane and oxygen with a flow ratio of 50:10, the etcher power was 70 W, and the etching time was 20 min;

[0077] (3) Using insulating spacers with a width of 30 mm and a thickness of 0.5 mm to form a frame around the second transparent conductive glass, and covering the first transparent conductive glass etched with a micro-cone structure on top of the frame to obtain a hollow structure; wherein the conductive surface of the second transparent conductive glass is arranged opposite to the conductive surface of the first transparent conductive glass;

[0078] (4) injecting an electrolyte into the hollow structure and sealing the four sides of the hollow structure with a UV-curing adhesive to obtain a radiative cooling device; wherein the electrolyte is prepared by dissolving silver nitrate, tetrabutylammonium bromide, copper chloride, and polyvinyl butyral in 20 mL of dimethyl sulfoxide, wherein the concentration of silver nitrate is 50 mmol / L, the concentration of tetrabutylammonium bromide is 250 mmol / L, the concentration of copper chloride is 10 mmol / L, and the concentration of polyvinyl butyral is 10%;

[0079] The non-conductive surface of the first transparent conductive glass etched with a micro-cone structure is connected to the negative electrode of the power supply, and the non-conductive surface of the second transparent conductive glass is connected to the positive electrode of the power supply. After applying a negative voltage of -3V for 30s, the radiative cooling device changes from a transparent state to a silver mirror state. At this time, the reflectivity of the radiative cooling device in the visible light band is 80%, and the emissivity in the mid-infrared band is 92%. Afterwards, after applying a positive voltage of +1V to the positive electrode of the power supply for 60s, the radiative cooling device fades from the silver mirror state to the transparent state.

[0080] Example 2:

[0081] (1) providing a first transparent conductive glass and a second transparent conductive glass; wherein the first transparent conductive glass and the second transparent conductive glass each include conductive surfaces and non-conductive surfaces opposite to each other in a thickness direction;

[0082] (2) etching a plurality of micro-cone structures on the non-conductive surface of the first transparent conductive glass; the micro-cone structures are conical in shape, the height of the conical structures is 1 μm, and the micro-cone structures are arranged in an array on the non-conductive surface;

[0083] (21) A hydrophilic solution is obtained by mixing ammonia water with a mass concentration of 25% and hydrogen peroxide with a mass concentration of 30% in a volume ratio of 1:1; after pretreating a first transparent conductive glass, the non-conductive surface of the first transparent conductive glass is immersed in the hydrophilic solution and a 5% sodium dodecylsulfate aqueous solution for 12 hours to obtain a hydrophilic first transparent conductive glass;

[0084] (22) Deionized water was added to a watch glass. The first transparent conductive glass was placed in the watch glass with its non-conductive surface facing upward. A 1% polystyrene emulsion (the solvent was anhydrous ethanol and water in a volume ratio of 1:1) was slowly added dropwise to the surface of the deionized water. When a large film appeared, a 5% sodium dodecylsulfate aqueous solution was added dropwise. The first transparent conductive glass was then slowly taken out. At this time, the polystyrene balls were transferred from the deionized water surface to the non-conductive surface of the first transparent conductive glass. The film was dried at room temperature (25°C) for 12 hours to obtain a single-layer polystyrene ball film.

[0085] (23) Reactive ion etching was performed on the surface of a single-layer polystyrene spherical film to obtain a micro-cone structure; wherein the etching gas was trifluoromethane and oxygen with a flow ratio of 20:1, the etcher power was 1 W, and the etching time was 100 min;

[0086] (3) Using insulating spacers with a width of 30 mm and a thickness of 0.5 mm to form a frame around the second transparent conductive glass, and covering the first transparent conductive glass etched with a micro-cone structure on top of the frame to obtain a hollow structure; wherein the conductive surface of the second transparent conductive glass is arranged opposite to the conductive surface of the first transparent conductive glass;

[0087] (4) injecting an electrolyte into the hollow structure and sealing the four sides of the hollow structure with a UV-curing adhesive to obtain a radiative cooling device; wherein the electrolyte is prepared by dissolving silver nitrate, tetrabutylammonium bromide, copper chloride, and polyvinyl butyral in 2 mL of dimethyl sulfoxide, wherein the concentration of silver nitrate is 1 mmol / L, the concentration of tetrabutylammonium bromide is 3 mmol / L, the concentration of copper chloride is 0.5 mmol / L, and the concentration of polyvinyl butyral is 8%;

[0088] The non-conductive surface of the first transparent conductive glass etched with a micro-cone structure is connected to the negative electrode of the power supply, and the non-conductive surface of the second transparent conductive glass is connected to the positive electrode of the power supply. After applying a negative voltage of -3V for 30s, the radiative cooling device changes from a transparent state to a silver mirror state. At this time, the reflectivity of the radiative cooling device in the visible light band is 68%, and the emissivity in the mid-infrared band is 87%. Afterwards, after applying a positive voltage of 1V to the positive electrode of the power supply for 60s, the radiative cooling device fades from the silver mirror state to the transparent state.

[0089] Example 3:

[0090] (1) providing a first transparent conductive glass and a second transparent conductive glass; wherein the first transparent conductive glass and the second transparent conductive glass each include conductive surfaces and non-conductive surfaces opposite to each other in a thickness direction;

[0091] (2) etching a plurality of micro-cone structures on the non-conductive surface of the first transparent conductive glass; the micro-cone structures are conical in shape, the height of the conical structures is 1.5 μm, and the micro-cone structures are arranged in an array on the non-conductive surface;

[0092] (21) A hydrophilic solution is obtained by mixing ammonia water with a mass concentration of 25% and hydrogen peroxide with a mass concentration of 30% in a volume ratio of 1:100; after pretreating a first transparent conductive glass, the non-conductive surface of the first transparent conductive glass is immersed in the hydrophilic solution and a 20% sodium dodecylsulfate aqueous solution for 8 hours, thereby obtaining a hydrophilic first transparent conductive glass;

[0093] (22) Deionized water was added to a watch glass. The first transparent conductive glass was placed in the watch glass with its non-conductive surface facing upward. A 50% polystyrene emulsion (the solvent was anhydrous ethanol and water in a volume ratio of 1:1) was slowly added dropwise to the surface of the deionized water. When a large film appeared, a 5% sodium dodecylsulfate aqueous solution was added dropwise. The first transparent conductive glass was then slowly taken out. At this time, the polystyrene balls were transferred from the deionized water surface to the non-conductive surface of the first transparent conductive glass. The film was dried at room temperature (25°C) for 12 hours to obtain a single-layer polystyrene ball film.

[0094] (23) Reactive ion etching was performed on the surface of a single-layer polystyrene spherical film to obtain a micro-cone structure; wherein, the etching gas was trifluoromethane and oxygen with a flow ratio of 30:10, the etcher power was 500 W, and the etching time was 1 min;

[0095] (3) Using insulating spacers with a width of 30 mm and a thickness of 0.5 mm to form a frame around the second transparent conductive glass, the first transparent conductive glass etched with a micro-cone structure is covered on top of the frame to obtain a hollow structure; wherein the conductive surface of the second transparent conductive glass is arranged opposite to the conductive surface of the first transparent conductive glass;

[0096] (4) injecting an electrolyte into the hollow structure and sealing the four sides of the hollow structure with a UV curing adhesive to obtain a radiant cooling device; wherein the electrolyte is prepared by dissolving silver nitrate, tetrabutylammonium bromide, copper chloride, and polyvinyl butyral in 200 mL of dimethyl sulfoxide, wherein the concentration of silver nitrate is 100 mmol / L, the concentration of tetrabutylammonium bromide is 700 mmol / L, the concentration of copper chloride is 100 mmol / L, and the concentration of polyvinyl butyral is 10%;

[0097] The non-conductive surface of the first transparent conductive glass etched with a micro-cone structure is connected to the negative electrode of the power supply, and the non-conductive surface of the second transparent conductive glass is connected to the positive electrode of the power supply. After applying a negative voltage of -3V for 30s, the radiative cooling device changes from a transparent state to a silver mirror state. At this time, the reflectivity of the radiative cooling device in the visible light band is 64%, and the emissivity in the mid-infrared band is 90%. Afterwards, after applying a positive voltage of 1V to the positive electrode of the power supply for 60s, the radiative cooling device fades from the silver mirror state to the transparent state.

[0098] Example 3:

[0099] Example 3 is basically the same as Example 1, except that in step (2), the height of the micro-cone structure is 500 nm.

[0100] In this example, applying a negative voltage of -3V for 30 seconds transformed the radiative cooling device from a transparent state to a silver mirror state. At this point, the device's reflectivity in the visible light band was 80%, and its emissivity in the mid-infrared band was 85%. Subsequently, applying a positive voltage of 1V for 60 seconds caused the device to fade from the silver mirror state to a transparent state.

[0101] Example 4:

[0102] Example 4 is substantially the same as Example 1, except that in step (4), the concentration of silver nitrate is 100 mmol / L, the concentration of tetrabutylammonium bromide is 200 mmol / L, the concentration of cupric chloride is 10 mmol / L, and the concentration of polyvinyl butyral is 10%.

[0103] In this example, applying a negative voltage of -3V for 30 seconds transformed the radiative cooling device from a transparent state to a silver mirror state. At this point, the device exhibited a reflectivity of 60% in the visible light band and an emissivity of 92% in the mid-infrared band. Subsequently, applying a positive voltage of 1V for 60 seconds to the positive terminal of the power supply caused the device to fade from the silver mirror state to a transparent state.

[0104] Example 6:

[0105] Example 6 is substantially the same as Example 1, except that in step (4), the concentration of silver nitrate is 100 mmol / L, the concentration of tetrabutylammonium bromide is 800 mmol / L, the concentration of cupric chloride is 10 mmol / L, and the concentration of polyvinyl butyral is 10%.

[0106] In this example, applying a negative voltage of -3V for 30 seconds transformed the radiative cooling device from a transparent state to a silver mirror state. At this point, the device exhibited a reflectivity of 62% in the visible light band and an emissivity of 92% in the mid-infrared band. Subsequently, applying a positive voltage of 1V for 60 seconds to the positive terminal of the power supply caused the device to fade from the silver mirror state to a transparent state.

[0107] Comparative Example 1:

[0108] Comparative Example 1 is substantially the same as Example 1, except that in step (2), the micro-cone structure is not etched on the non-conductive surface of the first transparent conductive glass.

[0109] In this comparative example, applying a negative voltage of -3V for 30 seconds transformed the radiative cooling device from a transparent state to a silver mirror state. At this point, the device exhibited a reflectivity of 80% in the visible light band and an emissivity of 80% in the mid-infrared band. Subsequently, applying a positive voltage of 1V for 60 seconds to the positive terminal of the power supply caused the device to fade from the silver mirror state to a transparent state.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a radiative cooling device, characterized in that: The preparation method comprises the following steps: (1) Providing a first transparent conductive glass and a second transparent conductive glass; wherein the first transparent conductive glass and the second transparent conductive glass each include a conductive surface and a non-conductive surface opposite to each other in a thickness direction; (2) etching a plurality of micro-cone structures on the non-conductive surface of the first transparent conductive glass; (3) Using insulating spacers to form a frame around the second transparent conductive glass, and covering the first transparent conductive glass etched with a micro-cone structure on top of the frame to obtain a hollow structure; wherein the conductive surface of the second transparent conductive glass is arranged opposite to the conductive surface of the first transparent conductive glass; (4) injecting an electrolyte into the hollow structure and sealing the four sides of the hollow structure to obtain the radiant cooling device; The non-conductive surface of the first transparent conductive glass etched with the micro-cone structure is connected to the negative electrode of the power supply, and the non-conductive surface of the second transparent conductive glass is connected to the positive electrode of the power supply. After voltage is applied, dynamic adjustment of the cooling effect of the radiant cooling device is achieved.

2. The preparation method according to claim 1, characterized in that In step (2): The micro-cone structure is obtained by etching through the following steps: (21) soaking the non-conductive surface of the first transparent conductive glass in a hydrophilic solution and a sodium dodecylsulfate aqueous solution in sequence to obtain a hydrophilic first transparent conductive glass; (22) adding a polystyrene emulsion dropwise onto the non-conductive surface of the first transparent conductive glass to obtain a single-layer polystyrene spherical film; (23) Reactive ion etching is performed on the single-layer polystyrene spherical film to obtain the micro-cone structure.

3. The preparation method according to claim 2, characterized in that In step (21): The hydrophilic solution is a mixed solution of ammonia water and hydrogen peroxide; wherein the mass concentration of the ammonia water is 22-28%, and the mass concentration of the hydrogen peroxide is 28-32%; The volume ratio of the ammonia solution to the hydrogen peroxide solution is (1-100): (1-100); The mass concentration of the sodium dodecylsulfate aqueous solution is 5-20%.

4. The preparation method according to claim 2, characterized in that In step (22): The solvent of the polystyrene emulsion is a mixed solvent of anhydrous ethanol and water; wherein the volume ratio of the anhydrous ethanol to water is (1-100): (1-100); The mass concentration of the polystyrene emulsion is 1-50%.

5. The preparation method according to claim 2, characterized in that In step (23): The reactive ion etching gas is trifluoromethane and oxygen; wherein the flow ratio of trifluoromethane to oxygen is (20-50): (1-20); The reactive ion etching time is 1-100 min, and the power of the etcher is 1-500W.

6. The preparation method according to claim 1 or 2, characterized in that The micro-cone structures are arranged in an array on the non-conductive surface; the height of each micro-cone structure is 1-2 μm.

7. The preparation method according to claim 1, characterized in that In step (3): The insulating gasket is polyimide tape or polytetrafluoroethylene; The insulating gasket has a width of 30-35 mm and a thickness of 0.2-0.6 mm.

8. The preparation method according to claim 1, characterized in that In step (4): The electrolyte is prepared by dissolving silver nitrate, tetrabutylammonium bromide, copper chloride and polyvinyl butyral in dimethyl sulfoxide.

9. The preparation method according to claim 8, characterized in that In the electrolyte, the concentration of silver nitrate is 0.1-100 mmol / L, the concentration of tetrabutylammonium bromide is 1-1000 mmol / L, the concentration of copper chloride is 0.1-100 mmol / L, and the mass concentration of polyvinyl butyral is 8-12%.

10. The preparation method according to claim 1, characterized in that In step (4), a negative pressure of -2 to -3 V is applied to the radiant cooling device to achieve deposition of the silver film, and a positive pressure of 0.5 to 1 V is applied to achieve dissolution of the silver film.

11. A radiative cooling device, characterized in that: The preparation method according to any one of claims 1 to 10 is used.

Images