A nano-carbon aerogel membrane and its preparation method

Abstract

This invention discloses a nano-carbon aerogel membrane and its preparation method. The nano-carbon dispersion used to prepare the nano-carbon aerogel membrane is passed through a micro / nano foaming machine to form uniform micro / nano bubbles inside. The foamed nano-carbon dispersion is then coated onto the surface of a current collector substrate and rapidly dried to obtain the nano-carbon aerogel membrane. The nano-carbon dispersion is prepared by dispersing nano-carbon, a binder, and a stabilizer in a solvent in a specific ratio. The preparation process of this invention is simple, requiring no complex operations such as freeze-drying or supercritical drying. It has low manufacturing costs, is simple and efficient, highly operable, and has broad commercial application prospects. The prepared nano-carbon aerogel membrane has high porosity (greater than 90%) and good compression resilience, and can be used in supercapacitors, electromagnetic shielding materials, flexible 3D electrodes, and 3D current collectors for batteries.

Description

Technical Field

[0001] This invention belongs to the field of high-performance carbon materials and their composite materials processing technology, specifically relating to a nano carbon aerogel membrane and its preparation method. Background Technology

[0002] Aerogels, with their three-dimensional porous structure, are characterized by ultralight weight, high porosity, and high specific surface area, making them ideal candidate materials for lightweight applications in electronic and energy devices. Since the discovery of silica aerogels, various aerogels have been extensively studied, such as polymer aerogels, nanocellulose aerogels, aramid nanofiber aerogels, cellulose nanofiber aerogels, graphene aerogels, carbon nanotube aerogels, MXene aerogels, and their composite aerogels. The diversity of aerogel types determines their different properties, and these aerogels have been widely applied in fields such as electronics, optics, and catalysis.

[0003] Aerogels are typically prepared by removing liquid solvents from wet gel precursors through critical point drying (CPD) or freeze-drying without damaging their three-dimensional porous network structure. However, both of these drying methods suffer from high costs, long processing times, cumbersome procedures, and are not suitable for large-scale production.

[0004] The present invention is made to address the aforementioned problems existing in the prior art. Summary of the Invention

[0005] To address at least one of the aforementioned technical problems, this invention provides a nano-carbon aerogel membrane and its preparation method. The method utilizes a micro-nano bubble generator to form uniform micro-nano bubbles in a carbon nanotube dispersion. Compared with conventional bubbles, micro-nano bubbles have smaller diameters, longer residence times in liquids, more stable phase interfaces, and larger specific surface areas. A three-dimensional porous nano-carbon aerogel membrane with stable structure, high elasticity, and good conductivity can be obtained through rapid drying.

[0006] The technical solution of this invention is as follows:

[0007] A method for preparing a nano-carbon aerogel membrane involves passing a nano-carbon dispersion for preparing the nano-carbon aerogel membrane through a micro-nano foaming machine to form uniform micro-nano bubbles inside, then coating the foamed nano-carbon dispersion onto the surface of a current collector substrate and drying it rapidly to obtain the nano-carbon aerogel membrane.

[0008] Preferably, the nano-carbon is dispersed in a solvent, and a certain amount of binder and stabilizer are added. The mixture is stirred continuously at a rate of 200-300 rpm for 20-30 minutes to ensure thorough and uniform mixing, thereby obtaining a nano-carbon dispersion. The nano-carbon solid content in the nano-carbon dispersion is 10%-15%, and the mass ratio of nano-carbon to binder and stabilizer is 20-10:0.7:0.3.

[0009] Preferably, the carbon nanotubes are multi-walled carbon nanotubes or a mixture of carbon nanotubes and graphene, with the carbon nanotubes having a purity greater than 99%, a diameter of 10–200 nm, and a length of 5–20 μm.

[0010] Preferably, the solvent is at least one selected from deionized water, alcohol, ethylene glycol, propanol, isopropanol, acetone, and N-methylpyrrolidone.

[0011] The adhesive is at least one of the following: polyvinylpyrrolidone, polyvinyl alcohol, polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, perfluorosulfonic acid polymer, alginate (lithium, sodium or potassium salt), and pectate (lithium, sodium or potassium salt).

[0012] The stabilizer is sodium carboxymethyl cellulose (CMC).

[0013] Preferably, the current collector substrate is one of copper foil, aluminum foil, copper mesh, and aluminum mesh.

[0014] Preferably, the dispersion flow rate during foaming is 150–300 L / h, and the air flow rate is 50–200 L / h.

[0015] Preferably, the micro / nano foaming machine consists of a swirling Venturi bubble generator and a Venturi tube, wherein the swirling Venturi bubble generator is installed downstream of the Venturi tube.

[0016] Preferably, the dimensions of the venturi tube are as follows: the length of both the converging and diverging sections is 40 mm, the diameter of both the inlet and outlet is 11 mm; the throat diameter is 1.5 mm, the distance from the air inlet to the throat is 35 mm, the inner diameter of the air inlet is 4 mm, and the length is 10 mm.

[0017] Preferably, the vortex-type Venturi bubble generator consists of three parts: an inlet fan-shaped baffle, an intermediate spiral channel, and an outlet divergence section; the inlet fan-shaped baffle has a three-blade structure with an outlet angle of 45°, a cone angle of 12°, and a divergence angle of 55°.

[0018] A nano-carbon aerogel membrane was prepared using the above-described method.

[0019] The beneficial effects of this invention are:

[0020] 1) This invention utilizes a micro-nano bubble generator to form uniform micro-nano bubbles in a carbon nanotube dispersion. Compared with conventional bubbles, micro-nano bubbles have smaller diameters, longer residence time in liquids, more stable phase interfaces, and larger specific surface areas. They can be rapidly dried to obtain a three-dimensional porous nanocarbon aerogel membrane with stable structure, high elasticity, and good conductivity.

[0021] 2) The preparation process of this invention is simple and does not require complex operations such as freeze drying and supercritical drying, which greatly reduces the manufacturing cost of aerogel materials. The method is simple and efficient, highly operable, and produces products with good consistency, and has broad commercial application prospects. The nano-carbon aerogel membrane prepared by this invention has high porosity (greater than 90%), low density, good conductivity, and excellent compression resilience, and can be used in fields such as supercapacitors, electromagnetic shielding materials, flexible 3D electrodes, and 3D current collectors for batteries. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0023] Figure 1 This is a schematic diagram of the foaming system used in this invention;

[0024] Figure 2 This is a schematic diagram of the micro / nano foaming mechanism used in this invention;

[0025] Figure 3 (a, b) are SEM images of the nano-carbon aerogel membrane prepared in Example 1 of the present invention at different magnifications;

[0026] Figure 3 (c,d) are SEM images of the carbon nanofilm prepared in Comparative Example 1 of this invention at different magnifications.

[0027] In the diagram: 1-1 is a liquid storage tank; 1-2 is a peristaltic pump; 1-3 is a liquid flow meter; 1-4 is a micro-nano foaming machine; 1-5 is a gas flow meter. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0029] The laboratory-scale foaming system used in this invention is as follows: Figure 1As shown, the foaming system includes a cylindrical storage tank 1-1 with a volume of 2000 mL, a peristaltic pump 1-2, a liquid flow meter 1-3, a micro / nano foaming machine 1-4, and a gas flow meter 1-5. The foaming process is as follows: driven by the peristaltic pump 1-2, the dispersion in the storage tank 1-1 passes through the liquid flow meter 1-3 and a valve, entering the micro / nano foaming machine 1-4. Air is automatically drawn into the dispersion through the air inlet, and the gas flow rate can be adjusted by the valve. All experiments were conducted at room temperature and atmospheric pressure, with the dispersion flow rate set in the range of 150–300 L / h and the air flow rate in the range of 50–200 L / h.

[0030] like Figure 2 As shown, the micro / nano bubble generator consists of a swirling Venturi bubble generator and a traditional Venturi tube. The swirling Venturi bubble generator is installed downstream of the traditional Venturi tube, forming the micro / nano bubble generator. The dimensions of the traditional Venturi tube are as follows: the length of both the converging and diverging sections is 40 mm, the diameter of both the inlet and outlet is 11 mm, and the throat diameter is 1.5 mm. The air inlet is 35 mm from the throat, with an inner diameter of 4 mm and a length of 10 mm (see attached diagram). Figure 2 (As shown in the left frame). This vortex-type Venturi bubble generator consists of three parts: an inlet fan-shaped baffle, a middle spiral channel, and an outlet divergence section; the inlet fan-shaped baffle has a three-blade structure, with an outlet angle of 45°, a cone angle of 12°, and a divergence angle of 55° (as shown in the attached figure). Figure 2 (As shown in the right box)

[0031] Each embodiment uses the above-described foaming system to treat the nano-carbon dispersion, thereby forming uniform micro-nano bubbles in the carbon nanotube dispersion.

[0032] Example 1

[0033] Add 100g of carbon nanotubes (Suzhou First Element, CNTp, the same below) to 900g of 40% alcohol solution. After ultrasonic treatment, add 70g of 10% sodium pectate solution and 30g of 10% sodium carboxymethyl cellulose solution to the mixture. Stir continuously at 200 rpm for 30 minutes to make it fully mixed and uniform, and the nano carbon dispersion is obtained.

[0034] The above-mentioned nano-carbon dispersion was circulated twice through a micro-nano foaming machine: driven by a peristaltic pump, the dispersion in the storage tank passed through a flow meter and valves and entered the micro-nano foaming machine; air was automatically drawn into the dispersion in the pipeline through the air inlet; the gas flow rate could be adjusted by the valves. All experiments were conducted at room temperature and atmospheric pressure, with the dispersion flow rate set at 150 L / h and the air flow rate at 75 L / h, to obtain a foamed nano-carbon dispersion.

[0035] The above-mentioned foamed nano-carbon dispersion was coated on the surface of aluminum foil and fed into a rapid drying chamber via a conveyor to obtain a nano-carbon aerogel film.

[0036] The nano-carbon aerogel film obtained in this embodiment has a thickness of 30 μm and an areal density of 184 mg / cm³. 3 The porosity is 90.8%.

[0037] Example 2

[0038] 100g of carbon nanotubes were added to 900g of 50% alcohol solution and sonicated. Then, 70g of 10% polyvinyl alcohol solution and 30g of 10% sodium carboxymethyl cellulose solution were added to the mixture. The mixture was stirred continuously at 200 rpm for 30 minutes to ensure thorough mixing and uniformity, thus obtaining the nano-carbon dispersion.

[0039] The above-mentioned nano-carbon dispersion was circulated three times through a micro-nano foaming machine, with the dispersion flow rate set at 200 L / h and the air flow rate at 100 L / h, to obtain a foamed nano-carbon dispersion.

[0040] The above-mentioned foamed nano-carbon dispersion was coated on the surface of aluminum foil and fed into a rapid drying chamber via a conveyor to obtain a nano-carbon aerogel film.

[0041] The nano-carbon aerogel film obtained in this embodiment has a thickness of 25 μm and an areal density of 153 mg / cm³. 3 The porosity is 92.3%.

[0042] Example 3

[0043] Add 90g of carbon nanotubes and 10g of graphene to 900g of 40% alcohol solution, sonicate, then add 70g of 10% polyvinyl alcohol solution and 30g of 10% sodium carboxymethyl cellulose solution to the mixture, and stir continuously at 200 rpm for 30 minutes to mix thoroughly and evenly to obtain the nano-carbon dispersion.

[0044] The above-mentioned nano-carbon dispersion was circulated 5 times through a micro-nano foaming machine, with the dispersion flow rate set at 300 L / h and the air flow rate at 150 L / h, to obtain a foamed nano-carbon dispersion.

[0045] The above-mentioned foamed nano-carbon dispersion was coated on the surface of aluminum foil and fed into a rapid drying chamber via a conveyor to obtain a nano-carbon aerogel film.

[0046] The nano-carbon aerogel film obtained in this embodiment has a thickness of 25 μm and a density of 118 mg / cm³. 3 The porosity is 94%.

[0047] Comparative Example 1

[0048] 100g of carbon nanotubes (Suzhou First Element, CNTp) were added to 900g of 40% alcohol solution. After ultrasonic treatment, 70g of 10% sodium pectate solution and 30g of 10% sodium carboxymethyl cellulose solution were added to the mixture. The mixture was stirred continuously at 200 rpm for 30 minutes to ensure thorough mixing and uniformity, thus obtaining the nano-carbon dispersion.

[0049] The above-mentioned nano-carbon dispersion was coated on the surface of aluminum foil and fed into a rapid drying chamber via a transmission machine to obtain a nano-carbon film.

[0050] The nanocarbon film obtained in this comparative example has a thickness of 30 μm and an areal density of 1.1 g / cm³. 3 The porosity is 45%.

[0051] SEM images of the nano-carbon aerogel membrane prepared in Example 1 at different magnifications are shown below. Figure 3 a, Figure 3 b, SEM images of the carbon nanofilm prepared in Comparative Example 1 at different magnifications are shown below. Figure 3 c. Figure 3 d. Comparison Figure 3 It is evident that the nano-carbon aerogel membrane prepared by the method of the present invention has a three-dimensional porous structure with pore sizes ranging from 100 nm to 3 μm, while the nano-carbon membrane obtained in the comparative example is significantly denser with fewer and smaller pores.

[0052] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for preparing a nanocarbon aerogel film, characterized by, The nanocarbon dispersion liquid for preparing the nanocarbon aerogel film is made to form uniform micro-nano bubbles inside by a micro-nano foaming machine, and then the foamed nanocarbon dispersion liquid is coated on the surface of the current collector substrate and quickly dried to obtain the nanocarbon aerogel film, wherein the porosity of the nanocarbon aerogel film is greater than 90%. The preparation process of the nanocarbon dispersion liquid is as follows: nanocarbon, binder and stabilizer are dispersed in a solvent in a certain proportion to obtain the nanocarbon dispersion liquid; the dispersion liquid flow rate is 150-300 L / h and the air flow rate is 50-200 L / h during foaming; The solid content of nanocarbon in the nanocarbon dispersion liquid is 10%-15%, the nanocarbon is multi-walled carbon nanotubes or a mixture of carbon nanotubes and graphene, and the mass ratio of nanocarbon, binder and stabilizer is 20-10:0.7:0.3; The micro-nano foaming machine is composed of a cyclone type Venturi bubble generator and a Venturi tube, the cyclone type Venturi bubble generator is installed downstream of the Venturi tube, the cyclone type Venturi bubble generator is composed of an inlet sector baffle, a middle spiral channel and an outlet divergent section, and the inlet sector baffle has a three-blade structure.

2. The method for producing a nanocarbon aerogel film according to claim 1, characterized by, The solvent is at least one of deionized water, alcohol, ethylene glycol, propanol, isopropanol, acetone and N-methyl pyrrolidone; The binder is at least one of polyvinylpyrrolidone, polyvinyl alcohol, polytetrafluoroethylene, polyethylene terephthalate, polybutylene terephthalate, perfluorosulfonic acid polymer, lithium alginate, sodium alginate, potassium alginate, pectin acid lithium salt, pectin acid sodium salt and pectin acid potassium salt; The stabilizer is sodium carboxymethyl cellulose.

3. The method for preparing the nano-carbon aerogel membrane according to claim 1, characterized in that, The current collector substrate is one of copper foil, aluminum foil, copper mesh and aluminum mesh.

4. A nanocarbon aerogel film, characterized by, The preparation method is prepared by any one of claims 1-3. The preparation method is prepared by any one of claims 1-3.

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