Pressure-resistant carbon-based mesoporous aerogel-like material and preparation method thereof

Abstract

The present application is a pressure-resistant carbon-based mesoporous aerogel material and a preparation method thereof. The pressure-resistant carbon-based mesoporous aerogel material comprises a large number of nanometer graphene petals and mesopores with a size of 2-50 nm, wherein the D50 of the pore size is 10 nm, and the structure enables the aerogel material to withstand a maximum static pressure of 50 MPa.

Description

Technical Field

[0001] This invention relates to a pressure-resistant carbon-based mesoporous aerogel material and its preparation method. Background Technology

[0002] Aerogel is a nanoscale porous solid material, also known as "frozen smoke," characterized by high porosity, low density, and high elasticity. Its internal particles are extremely small, typically on the nanometer scale. Because aerogels generally contain a large amount of air, they have excellent thermal insulation properties; one inch of aerogel is equivalent to the insulation function of 20 to 30 pieces of ordinary glass. Furthermore, although aerogels appear fragile, they are actually very strong and durable, generally able to withstand high pressure and high temperatures, making them excellent thermal insulation materials. Traditional aerogels are generally silica aerogels, but newer aerogels can also be made from graphene. Compared to traditional silica aerogels, graphene aerogels can be shaped arbitrarily and have excellent elasticity, returning to their original shape even after being compressed by 80%. In addition, it has an ultra-fast and ultra-high adsorption capacity for organic solvents. Existing oil-absorbing products can generally only absorb about 10 times their own weight in liquid, while graphene aerogels can absorb hundreds of times their weight in liquid, and it only absorbs oil, not water. Currently, the main method for preparing aerogels is to first prepare a gel using the sol-gel method, and then use air to replace the liquid in the gel through drying technology. However, this method is lengthy and complex and has not yet been commercially applied. In addition, the graphene aerogels prepared by gel drying have a relatively rough structure, cannot obtain a mesoporous structure, and have a lot of room for improvement in pressure resistance. Summary of the Invention

[0003] This invention aims to provide a pressure-resistant carbon-based mesoporous aerogel material and its preparation method. Utilizing a combination of arc technology and electron cyclotron resonance technology, carbon-based aerogels can be produced rapidly and on a large scale, overcoming the problem of lengthy processes and inability to achieve rapid industrial manufacturing in traditional aerogel preparation methods. Simultaneously, the manufactured novel aerogel possesses a novel mesoporous structure with highly concentrated pore sizes; 90% of the mesopores are smaller than 5 nm. This mesoporous structure significantly improves the mechanical strength of the aerogel, enabling it to withstand higher pressures than ordinary aerogels. It is a novel aerogel that is pressure-resistant, has good thermal insulation properties, and can be mass-produced.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A pressure-resistant carbon-based mesoporous aerogel material includes nanographene lobes, mesopores between nanographene lobes, mesoporous graphene flowers composed of nanographene lobes and mesopores, and nanosilicon / silica may be present in the mesopores. The pressure-resistant carbon-based mesoporous aerogel material is composed of a large number of mesoporous graphene flowers or mesoporous graphene flowers and nanosilica / silica therein.

[0006] The graphene nanoparticles are graphene nanosheets shaped like flower petals, with a diameter of 8–25 nm and a thickness of 4–7 carbon atom layers.

[0007] The mesopore size between the nanographene lobes is 2-50 nm, and the pores with a size <10 nm account for >50% of the total pore volume, the most probable (most numerous) mesopore size is <4 nm, and the average pore diameter is <10 nm.

[0008] Furthermore, when the nanographene lobes and mesopores are used to form three-dimensional graphene and pressure-resistant carbon-based mesoporous aerogel materials, they completely maintain their original structure and size. Specifically, the nanographene lobes do not aggregate or stack, and the mesopores do not collapse or expand.

[0009] Furthermore, the size of the nano-silicon / silicon oxide in the mesopores is 2-40 nm, and the nano-silicon / silicon oxide is located in the mesopores between the graphene lobes, and is uniformly and fully distributed in the mesoporous graphene flowers.

[0010] Furthermore, hydrofluoric acid can be used to remove nano-silicon / silica from the mesopores. Hydrofluoric acid does not affect the size and structure of the nano-graphene lobes and mesopores. After removal, a pressure-resistant carbon-based mesoporous aerogel material with unchanged structure and size is obtained.

[0011] Another objective of this invention is that the mesoporous graphene flower structure composed of nanographene lobes and mesopores can withstand a maximum static pressure of 50 MPa. That is, applying a maximum static pressure of 50 MPa to the material will not damage the microstructure of the material. After the pressure is released, the mesoporous graphene flower structure and size remain intact, while the silicon dioxide quantum dots within it are also protected intact. In other words, the pressure-resistant carbon-based mesoporous aerogel material can withstand a maximum static pressure of 50 MPa.

[0012] This invention utilizes arc-enhanced electron cyclotron resonance plasma, with methane, argon, hydrogen gas, and micron-sized silicon powder as raw materials, to prepare pressure-resistant carbon-based mesoporous aerogel materials. For example... Figures 5-6 As shown

[0013] 1) Using argon as a carrier gas, nano-silicon powder is transported to an arc gun as a precursor (plasma gas 1). The argon is ionized in the arc gun to form an argon plasma arc. The resulting high-temperature arc vaporizes and ionizes the nano-silicon, forming a mixed arc of argon and silicon. This arc is directly injected into the electron cyclotron resonance plasma cavity as a precursor for subsequent processes. For example... Figure 5 As shown

[0014] 2) Methane and hydrogen (plasma gas 2) enter the electron cyclotron resonance plasma cavity. Under the dual splitting effect of electron cyclotron resonance and the aforementioned electric arc, plasma is formed. After mixing with the plasma that entered the cavity in 1), it reaches the substrate with applied radio frequency bias and deposits a pressure-resistant carbon-based mesoporous aerogel material on the substrate. The silicon plasma forms silicon quantum dots, the methane plasma forms nano-graphene lobes, and argon and hydrogen plasmas are used to control the microstructure and size of the material.

[0015] 3) Remove the substrate from the cavity and collect the pressure-resistant carbon-based mesoporous aerogel material on the substrate. The nano-silicon in the substrate will transform into nano-silica after contact with air. If the collection process is carried out in an inert gas environment, the silicon quantum dots will not transform into nano-silica.

[0016] Furthermore, the pressure-resistant carbon-based mesoporous aerogel material can be broken down by shearing to obtain pressure-resistant carbon-based mesoporous aerogel material particles with a size of 1-15 μm. The structure and size of the nano-graphene petals and mesopores in the pressure-resistant carbon-based mesoporous aerogel material particles, as well as the structure and size of the nano-silicon / silica, remain consistent with those before breaking down.

[0017] Furthermore, the broken, pressure-resistant carbon-based mesoporous aerogel material can also be used in lithium-ion batteries as a novel silicon-carbon anode material.

[0018] Furthermore, the silica or silicon can be removed to obtain a mesoporous carbon aerogel material with a carbon content >99.99%.

[0019] This invention utilizes arc-enhanced electron cyclotron resonance plasma, with methane, argon, and hydrogen gases, and nano-silicon as raw materials, to prepare a pressure-resistant carbon-based mesoporous aerogel material. The steps are as follows:

[0020] 1) Using argon as a carrier gas, nano-silicon powder is transported to an arc gun as a precursor (plasma gas 1). The argon is ionized in the arc gun to form an argon plasma arc. The resulting high-temperature arc vaporizes and ionizes the nano-silicon, forming a mixed arc of argon and silicon. This arc is directly injected into the electron cyclotron resonance plasma cavity as a precursor for subsequent processes. For example... Figure 5 As shown

[0021] 2) Methane and hydrogen (plasma gas 2) enter the electron cyclotron resonance plasma cavity. Under the dual splitting effect of electron cyclotron resonance and the aforementioned electric arc, plasma is formed. After mixing with the plasma that entered the cavity in 1), it reaches the substrate on which radio frequency bias is applied, and a pressure-resistant carbon-based mesoporous aerogel material is deposited on the substrate.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The technical method of this invention is efficient and fast, enabling rapid industrial mass production of carbon-based aerogels.

[0024] 2) The material of the present invention has a mesoporous structure, which greatly improves the mechanical strength of the aerogel and can withstand high pressure without being damaged.

[0025] 3) Compared with traditional aerogel technology, this invention is very environmentally friendly, does not produce any wastewater, and the residual silicon in the exhaust gas generated during the production process can be recycled after filtration. The remaining exhaust gas is hydrogen, which can be collected and used as industrial hydrogen, making it economical and environmentally friendly.

[0026] 4) The aerogel material of the present invention can be used as an active material for a novel silicon-carbon lithium battery anode after being broken down.

[0027] Figure and Table Description

[0028] Figure 1 Photographs of the pressure-resistant carbon-based mesoporous aerogel material of the present invention.

[0029] Figure 2 Scanning electron microscope images of the microstructure of the pressure-resistant carbon-based mesoporous aerogel material of the present invention.

[0030] Figure 3 Transmission electron microscope images of graphene nanolobes and mesoporous microstructures in this invention.

[0031] Figure 4 A schematic diagram of the arc gun structure used in this invention.

[0032] Figure 5 A schematic diagram of the electron cyclotron resonance cavity structure used in this invention.

[0033] Figure 6 The thermal conductivity of pressure-resistant carbon-based mesoporous aerogel materials

[0034] Figure 7 Rate performance diagram of pressure-resistant carbon-based mesoporous aerogel material as a lithium battery anode

[0035] Figure 8 Cyclic performance of pressure-resistant carbon-based mesoporous aerogel materials as lithium-ion battery anodes

[0036] Table 1: Performance data of pressure-resistant carbon-based mesoporous aerogel materials as lithium-ion battery anodes

[0037] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0040] Example 1: Preparation of pressure-resistant carbon-based mesoporous aerogel material and its thermal insulation performance test

[0041] As Figure 4 and 5 Argon gas at a flow rate of 1 slm is first introduced into the inlets of plasma gases 1 and 2 to purge air from the cavity and fill the entire cavity with argon gas. Then, the argon gas flow rate is turned off. Figure 4 The plasma shown is introduced with 1 slm of argon carrier gas at port 1, mixed with micron-sized silicon powder at a mass flow rate of 0.25 g / min. The arc gun nozzle has a diameter of 1.2 mm, the power supply is set to a pulsed current of 60 A, a single pulse duration of 40 μs, and a duty cycle of 50%. Simultaneously, in... Figure 5 A mixture of methane and hydrogen gas is introduced into each of the plasma ports shown in the figure. The flow rate of methane is 600 sccm and the flow rate of hydrogen is 4.8 slm. The microwave frequency in the electron cyclotron resonator is 2.45 GHz, introduced through the dielectric windows around the cavity as indicated by the arrows in the figure. The power is 1000 W, the magnetic field strength parallel to the microwave direction is 875 G, the heating zone temperature is 1400 °C, the substrate is a graphite substrate, the radio frequency bias voltage on the substrate is 13.56 MHz, the magnetic field strength of the multi-stage magnet is 0.15 T, and the gas pressure in the electron cyclotron resonator is 1 mtorr. After generating plasma in an arc gun and an electron cyclotron resonant cavity, the raw materials are mixed within the cavity to achieve reactive deposition of a pressure-resistant carbon-based mesoporous aerogel material on a graphite substrate. After 30 minutes, 15g of the pressure-resistant carbon-based mesoporous aerogel material is obtained, containing 6g of nano-silicon material and the remaining 9g of nano-graphene petrosities. The material is then collected from the graphite substrate, and the nano-silicon material oxidizes to nano-silicon oxide in air. The pressure resistance and thermal insulation properties of the pressure-resistant carbon-based mesoporous aerogel material are tested. The material is first shaped using a mold as shown in the image. Figure 1The block shown is subjected to a longitudinal pressure of 50 MPa for 5 minutes. The pressure is then released, and the material returns to its initial shape. The steps for testing the thermal insulation performance are as follows: The thermal conductivity is used to quantify the material's insulation effect. A fixed thermal conductivity meter is used to measure the thermal conductivity. The test principle is the transient hot wire method. The model is TC 3010. The measurement range of this device is 0.005~100W / (m·K), with an accuracy of ±2~3% and a resolution of 0.001W / (m·K). The test range is room temperature to 150℃. The measurement time is 20 seconds. The test results are as follows. Figure 6 As shown in the figure, the thermal conductivity curves indicate that the material has excellent thermal insulation properties. Curve 1 represents the data for commercial nano-silica aerogel felt, and curve 2 represents the pressure-resistant carbon-based mesoporous aerogel material of this embodiment.

[0042] Example 2: Preparation of pressure-resistant carbon-based mesoporous aerogel material and its performance in lithium-ion battery anodes

[0043] As Figure 4 and 5 Argon gas at a flow rate of 1 slm is first introduced into the inlets of plasma gases 1 and 2 to purge air from the cavity and fill the entire cavity with argon gas. Then, the argon gas flow rate is turned off. Figure 4 The plasma shown is introduced with 1 slm of argon carrier gas at port 1, mixed with micron-sized silicon powder at a mass flow rate of 0.25 g / min. The arc gun nozzle has a diameter of 1.2 mm, the power supply is set to a pulsed current of 60 A, a single pulse duration of 40 μs, and a duty cycle of 50%. Simultaneously, in... Figure 5 The plasma ports shown in the diagram are filled with a mixture of methane and hydrogen gas, with a methane flow rate of 600 scc and a hydrogen flow rate of 4.8 slm. The microwave frequency in the electron cyclotron resonator is 2.45 GHz, introduced through the dielectric windows around the cavity as indicated by the arrows in the diagram, with a power of 1000 W. The magnetic field strength parallel to the microwave direction is 875 G, the heating zone temperature is 1400 °C, the substrate is a graphite substrate, the radio frequency bias voltage on the substrate is 13.56 MHz, the magnetic field strength of the multi-stage magnet is 0.15 T, and the gas pressure in the electron cyclotron resonator is 1 mtorr. The raw materials are mixed after plasma is generated in an arc gun and an electron cyclotron resonant cavity, and then reacted and deposited on a graphite substrate to form a pressure-resistant carbon-based mesoporous aerogel. After 30 minutes, 15g of pressure-resistant carbon-based mesoporous aerogel is obtained, of which 6g is nano-silicon material and the remaining 9g is nano-graphene petriles. After being removed in an inert gas environment, the pressure-resistant carbon-based mesoporous aerogel is collected from the graphite substrate. During subsequent use, the material is kept in an inert gas environment to prevent the nano-silicon in the material from being oxidized.

[0044] The prepared pressure-resistant carbon-based mesoporous aerogel material was used as the lithium-ion battery anode material. It was mixed with a binder, conductive agent, and dispersant to prepare an aqueous slurry in the following proportions: anode material 93: conductive agent 2: dispersant 2: binder 3. The conductive agent was one of SP / CB / KS-600, the dispersant was CMC, and the binder was SBR. The slurry was poured onto the copper foil of the anode current collector, and the coating height was adjusted. After drying, the net thickness was between 80-100 μm. An automatic coating machine was used for uniform coating. The slurry surface was observed to be smooth, uniform, and free of particles. The electrode was heated to approximately 80°C for 10 minutes to dry, and then placed in a drying oven at 80°C for 4-6 hours to completely remove moisture. After drying, the electrode thickness was tested, gradually rolled to a thickness of 50-60 micrometers, and the areal density was tested to be 40-60 g / m³. 2 The compacted density is 0.8–1 g / cm³. 3 The prepared electrode sheets and lithium metal sheets were assembled into coin cells. Battery performance was tested using either current density or rate testing methods at different rates: 0.1C, 0.5C, 1C, 3C, and 5C. Four to six battery sets were fabricated from each electrode sheet. Data with significant differences (more than 10%) were discarded, and the average value was taken. The test results are shown below. Figure 7 As shown in 8 and Table 1.

[0045] Table 1: Electrical performance data of pressure-resistant carbon-based mesoporous aerogel materials as lithium-ion battery anodes

[0046]

[0047] Example 3: Preparation of mesoporous carbon aerogel materials

[0048] As Figure 4 and 5 Argon gas at a flow rate of 1 slm is first introduced into the inlets of plasma gases 1 and 2 to purge air from the cavity and fill the entire cavity with argon gas. Then, the argon gas flow rate is turned off. Figure 4 The plasma shown is introduced with 1 slm of argon carrier gas at port 1, mixed with micron-sized silicon powder at a mass flow rate of 0.25 g / min. The arc gun nozzle has a diameter of 1.2 mm, the power supply is set to a pulsed current of 60 A, a single pulse duration of 40 μs, and a duty cycle of 50%. Simultaneously, in... Figure 5A mixture of methane and hydrogen gas is introduced into each of the plasma ports shown in the figure. The flow rate of methane is 600 sccm and the flow rate of hydrogen is 4.8 slm. The microwave frequency in the electron cyclotron resonator is 2.45 GHz, introduced through the dielectric windows around the cavity as indicated by the arrows in the figure. The power is 1000 W, the magnetic field strength parallel to the microwave direction is 875 G, the heating zone temperature is 1400 °C, the substrate is a graphite substrate, the radio frequency bias voltage on the substrate is 13.56 MHz, the magnetic field strength of the multi-stage magnet is 0.15 T, and the gas pressure in the electron cyclotron resonator is 1 mtorr. After generating plasma in an arc gun and an electron cyclotron resonant cavity, the raw materials are mixed within the cavity to achieve the reaction deposition of a pressure-resistant carbon-based mesoporous aerogel material on a graphite substrate. After 30 minutes, 15g of pressure-resistant carbon-based mesoporous aerogel material is obtained, containing 6g of nano-silicon material and the remaining 9g of nano-graphene petrosity. The pressure-resistant carbon-based mesoporous aerogel material is then collected from the graphite substrate, where the nano-silicon is oxidized to nano-silica in air. Immersing the pressure-resistant carbon-based mesoporous aerogel material in a 10% concentration of hydrofluoric acid and heating for 2 hours completely removes the silica. Repeated rinsing with plenty of water to remove the hydrofluoric acid yields the mesoporous carbon aerogel material.

Claims

1. A method for preparing a pressure-resistant carbon-based mesoporous aerogel material, characterized in that, The pressure-resistant carbon-based mesoporous aerogel material includes nano-graphene lobes, mesopores between nano-graphene lobes, mesoporous graphene flowers composed of nano-graphene lobes and mesopores, mesopores filled with nano-silicon / nano-silica, and pressure-resistant carbon-based mesoporous aerogel materials composed of a large number of mesoporous graphene flowers or mesoporous graphene flowers and nano-silicon / nano-silica within them. The production steps and parameters are as follows: A pressure-resistant carbon-based mesoporous aerogel material was prepared using arc-enhanced electron cyclotron resonance plasma as the reaction medium and methane, argon, hydrogen gas, and micron-sized silicon powder as raw materials. 1) Using 1slm argon as the carrier gas, micron-sized silicon powder is transported to the arc gun as a precursor. The argon is ionized in the arc gun to form an argon plasma arc. The generated high-temperature arc vaporizes and ionizes the 0.25g / min mass flow rate of micron-sized silicon to form a mixed arc of argon and silicon. This arc is directly injected into the electron cyclotron resonance plasma cavity as a precursor for subsequent processes. 2) Methane with a flow rate of 600 sccm and hydrogen with a flow rate of 4.8 slm enter the electron cyclotron resonance plasma cavity. Under the dual splitting effect of electron cyclotron resonance and the aforementioned electric arc, plasma is formed. It mixes with the plasma entering the cavity in 1) and then reaches the substrate on which radio frequency bias is applied, and a pressure-resistant carbon-based mesoporous aerogel material is deposited on the substrate. 3) The microwave frequency in the electron cyclotron resonant cavity is 2.45 GHz, introduced through the dielectric window around the cavity, with a power of 1000 W, a magnetic field strength parallel to the microwave direction of 875 G, a heating zone temperature of 1400 ℃, a graphite substrate, an RF bias voltage of 13.56 MHz and 1000 W on the substrate, a magnetic field strength of 0.15 T for the multi-stage magnet, and a gas pressure of 1 mtorr in the electron cyclotron resonant cavity. 4) Silicon plasma forms nano-silicon, methane plasma forms nano-graphene petals, argon plasma is used to assist in the vaporization and ionization of micron-sized silicon, as well as to regulate the microstructure and size of the material, and hydrogen plasma is used to regulate the microstructure and size of the material. 5) Remove the substrate from the cavity and collect the pressure-resistant carbon-based mesoporous aerogel material on the substrate. The nano-silicon in the substrate will transform into nano-silica after contact with air. If the collection process is carried out in an inert gas environment, the nano-silicon will not transform into nano-silica.

2. The method for preparing the pressure-resistant carbon-based mesoporous aerogel material according to claim 1, characterized in that, The graphene nanoparticles are graphene nanosheets shaped like flower petals, with a diameter of 8-25 nm and a thickness of 4-7 carbon atom layers.

3. The method for preparing the pressure-resistant carbon-based mesoporous aerogel material according to claim 1, characterized in that, The mesopore size between the nanographene lobes is 2~50nm, and the pores with a mesopore size <10nm account for ≥50% of the total pore volume, the most probable mesopore size is <4nm, and the average pore diameter is ≤10nm.

4. The method for preparing the pressure-resistant carbon-based mesoporous aerogel material according to claim 1, characterized in that, When the nanographene petals and mesopores form mesoporous graphene flowers and pressure-resistant carbon-based mesoporous aerogel materials, they completely maintain their original structure and size. The nanographene petals do not aggregate or stack, and the mesopores do not collapse or expand.

5. The method for preparing the pressure-resistant carbon-based mesoporous aerogel material according to claim 1, characterized in that, The size of the nano-silicon / silicon oxide in the mesopores is 2~40nm. The nano-silicon / silicon oxide is located in the mesopores between the graphene lobes and is uniformly and fully distributed in the mesoporous graphene flowers.

6. The method for preparing the pressure-resistant carbon-based mesoporous aerogel material according to claim 1, characterized in that, Hydrofluoric acid was also used to remove nano-silicon / silicon oxide from the mesopores. Hydrofluoric acid does not affect the size and structure of the nano-graphene lobes and mesopores. After removal, a pressure-resistant carbon-based mesoporous aerogel material with unchanged structure and size was obtained.

7. The method for preparing the pressure-resistant carbon-based mesoporous aerogel material according to claim 1, characterized in that, The pressure-resistant carbon-based mesoporous aerogel material was broken down by shearing to obtain pressure-resistant carbon-based mesoporous aerogel material particles with a size of 1~15μm. The structure and size of the nanographene lobes and mesopores in the pressure-resistant carbon-based mesoporous aerogel material particles, as well as the structure and size of the nanosilicon / silica, remained consistent with those before breaking.

8. The method for preparing the pressure-resistant carbon-based mesoporous aerogel material according to any one of claims 1 to 7, characterized in that, The broken, pressure-resistant carbon-based mesoporous aerogel material is used in lithium-ion batteries as a silicon-carbon anode material.

9. The method for preparing the pressure-resistant carbon-based mesoporous aerogel material according to claim 1, characterized in that, The silica or silicon is removed to obtain a mesoporous carbon aerogel material with a carbon content >99.99%.

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