CN109851312B - Graphene heat insulation film and preparation method thereof - Google Patents
Graphene heat insulation film and preparation method thereof Download PDFInfo
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- CN109851312B CN109851312B CN201811603259.XA CN201811603259A CN109851312B CN 109851312 B CN109851312 B CN 109851312B CN 201811603259 A CN201811603259 A CN 201811603259A CN 109851312 B CN109851312 B CN 109851312B
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Abstract
The invention provides a preparation method of a graphene thermal insulation material, which comprises the following steps: mixing the graphene carbon material dispersion system with the hollow microsphere and/or aerogel dispersion system liquid to obtain composite slurry; defoaming, coating and drying the composite slurry to form a composite film; and carrying out heat treatment on the composite film to decompose functional groups on the graphene carbon material, and finally forming the graphene heat insulation film. According to the graphene heat insulation film provided by the invention, graphene/graphene oxide composite aerogel or cenospheres are adopted to form graphene in-plane directional arrangement (minimum energy assembly among sheet layers, hydrogen bond and capillary pressure assembly), and aerogel nanoparticles and/or cenospheres are positioned among graphene sheet layers. The graphene has tens of thousands of layers to form an effective reflecting partition plate, and the aerogel or hollow microspheres between the layers play a role in reducing the contact of graphene sheets and increasing the thermal resistance. Gaps formed between graphene layers and the aerogel or the hollow microspheres are small, and convection of gas inside the graphene layers is blocked.
Description
Technical Field
The invention relates to a heat insulation material and a preparation method thereof, in particular to a heat insulation carbon material and a preparation method thereof.
Background
The lithium ion battery is used as an energy drive for the electric automobile, certain potential safety hazards exist in the lithium ion battery at present, and the electric automobile fires are frequently reported every year. In order to solve or delay the thermal runaway of the electric automobile and even the ignition, engineers make various efforts, wherein a heat insulation film is adopted between each electric core to separate the electric cores, so that the instant ignition caused by the thermal runaway of one electric core is avoided.
The pre-oxidized fiber aerogel felt has a thermal conductivity coefficient of less than 0.018W/m.K, has excellent heat insulation performance, and is applied to a power battery pack to delay the time of dangerous states such as runaway and ignition of the battery pack. However, it is too costly; during processing, the dust pollution is large.
Patent CN201710384128.6 is a method for preparing a closed-cell graphene oxide-based heat insulation material, which comprises preparing graphite oxide into emulsion, and freeze-drying for 5-7 days. The freeze drying has high manufacturing cost and long production period.
The statements in the background section are merely prior art as they are known to the inventors and do not, of course, represent prior art in the field.
Disclosure of Invention
In order to overcome one or more of the problems in the prior art, the invention provides a graphene thermal insulation material with good thermal insulation effect and low density;
the invention also aims to provide a preparation method of the graphene thermal insulation material.
The above object is achieved by the following technical solutions.
A preparation method of a graphene thermal insulation material comprises the following steps:
mixing the graphene carbon material dispersion system with the hollow microsphere and/or aerogel dispersion system liquid to obtain composite slurry;
defoaming, coating and drying the composite slurry to form a composite film; and
and carrying out heat treatment on the composite film to decompose functional groups on the graphene carbon material, and finally forming the graphene heat insulation film.
According to one aspect of the invention, the graphene carbon material is graphene oxide and/or graphene.
According to one aspect of the invention, the graphene oxide has a carbon content of 48-60 wt% and an oxygen content of 41-53 wt%.
According to one aspect of the present invention, the graphene is graphene prepared by a redox method.
According to one aspect of the invention, the graphene carbon material is graphene oxide or a mixture of graphene oxide and a small amount of graphene, and the amount of doped graphene is not less than 5 according to the mass ratio of graphene oxide to graphene.
More preferably, the graphene carbon material is graphene oxide.
According to an aspect of the present invention, in the graphene carbon material dispersion system, the content of the graphene carbon material and the first solvent is 3 to 10 wt%, and preferably 8 wt%.
Preferably, the first solvent is selected from water and/or NMP; further preferably, the first solvent is water and NMP according to (3-5): 1, preferably, the first solvent is water and NMP in a mass ratio of 4: the mass ratio of 1 is configured as a mixed solvent.
According to one aspect of the invention, the graphene carbon material system is prepared according to the following method:
adding the graphene carbon material into the first solvent, and stirring uniformly by using a planetary stirrer at 300-2200 rpm.
Preferably, the slurry is stirred until the fineness of the slurry is less than 20 mu m and the viscosity is 20000-40000 mPa.s.
Preferably, stirring is carried out for 60. + -.30 min.
According to one aspect of the invention, the insulating material is a cenosphere and/or aerogel.
According to one aspect of the present invention, the heat insulating material is cenospheres, or a mixed material in which aerogel is mixed in the cenospheres, and the mixing amount of the aerogel is in the following ratio: the mass ratio of the aerogel is more than or equal to 0.5.
Preferably, when the heat insulating material is a mixed material in which aerogel is mixed in cenospheres, the mixing amount of aerogel is in the range of cenospheres: the mass ratio of the aerogel is preferably more than or equal to 1; the best is hollow micro-bead: the mass ratio of the aerogel is 3: 2.
According to one aspect of the present invention, the heat insulating material dispersion system includes a heat insulating material and a second solvent, and the heat insulating material is contained in an amount of 3 to 15 wt%, preferably 5 wt%.
Preferably, the second solvent is selected from water and/or NMP; further preferably, the second solvent is water and NMP according to (3-5): 1, preferably, the second solvent is water and NMP in a mass ratio of 4: the mass ratio of 1 is configured as a mixed solvent.
According to one aspect of the invention, the thermal insulation material is prepared as follows:
and adding the heat insulating material into the second solvent, and uniformly stirring to form stable suspension without sedimentation.
According to one aspect of the invention, the cenospheres have a particle size of 1 to 50 μm, preferably 5 μm.
According to one aspect of the invention, the wall thickness of the air beads is 0.2-2.0 μm, preferably 1.0 μm.
According to one aspect of the invention, the cenospheres are selected from the group consisting of glass cenospheres, ceramic cenospheres.
According to one aspect of the invention, the aerogel has a particle size of 20 to 100nm, preferably 50 nm.
According to one aspect of the invention, the aerogel is selected from silica aerogels.
According to one aspect of the invention, the liquid-liquid mixing method comprises the following specific steps: adding the gas insulation material dispersion system into the graphene carbon material dispersion system according to the proportion relation that the heat insulation material accounts for 0.5-10 wt% of the graphene carbon material, and uniformly dispersing.
Preferably, the heat insulation material accounts for 1 wt% of the graphene carbon material.
Preferably, the dispersion is carried out uniformly at a stirring speed of 300-1000 rpmg.
According to one aspect of the invention, the defoaming method comprises the following steps: and (4) defoaming by continuous thin film or stirring and defoaming in vacuum. According to one aspect of the invention, the slurry is knife coated or die coated onto the base tape with the base tape as a support.
According to one aspect of the present invention, the composite paste is coated to a thickness of 2 to 3 mm.
According to one aspect of the invention, the drying temperature is room temperature to 90 ℃, and the drying time is 1 to 3 hours;
according to one aspect of the invention, the drying temperature is 50-90 ℃ and the drying time is 2 hours.
According to one aspect of the invention, the thickness of the composite film formed after drying is 80 to 150 μm.
According to one aspect of the invention, the temperature of the heat treatment is 100-300 ℃, and the constant temperature is kept for 2-12h at the heat treatment temperature.
Preferably, the temperature of the heat treatment is 200 ℃, and the constant temperature is kept for 3 hours.
According to one aspect of the invention, the heat treatment temperature is constant until the composite film expands to a thickness of 300-1000 μm;
according to one aspect of the invention, the temperature rise rate of the heat treatment is 0.01-2 ℃/min, the temperature is raised to the heat treatment temperature, and then the temperature is constant.
According to one aspect of the present invention, the apparatus used for the heat treatment may be an oven, a heating furnace, a tunnel furnace, or the like.
The graphene heat insulation film comprises graphene and cenospheres and/or aerogel, wherein the cenospheres and/or aerogel are distributed among layers of the graphene and packaged in a network formed among graphene sheets.
According to one aspect of the invention, the thermal conductivity of the graphene thermal insulation film is below 0.018W/m-K.
According to one aspect of the invention, the graphene thermal insulation film has a density of 0.15g/cm3The following.
According to an aspect of the present invention, the compressive strength of the graphene thermal insulation film is greater than 10 MPa.
According to one aspect of the present invention, the graphene has an oxygen content of 10 to 30 wt%. According to the invention, the oxygen content of graphene in the graphene heat insulation film is finally controlled to be 10-30 wt%, when the oxygen content of graphene is less than 10 wt%, the heat insulation performance of the heat insulation film is obviously reduced, when the oxygen content of graphene is more than 30 wt%, the temperature resistance of the heat insulation film is obviously reduced, and the oxygen content of graphene in the heat insulation film is ensured to be 10-30 wt%, so that the performance of the graphene heat insulation film is optimal.
According to the graphene heat insulation film provided by the invention, graphene/graphene oxide composite aerogel or cenospheres are adopted to form graphene in-plane directional arrangement (minimum energy assembly among sheet layers, hydrogen bond and capillary pressure assembly), and aerogel nanoparticles and/or cenospheres are positioned among graphene sheet layers. The graphene has tens of thousands of layers to form an effective reflecting partition plate, and the aerogel or hollow microspheres between the layers play a role in reducing the contact of graphene sheets and increasing the thermal resistance. Gaps formed between graphene layers and the aerogel or the hollow microspheres are small, and convection of gas inside the graphene layers is blocked. The invention realizes low heat conduction, inhibits air heat convection and infrared reflection, and prepares the excellent heat insulation film. And the aerogel nanoparticles and/or the hollow microspheres are encapsulated between graphene layers, so that the product has no powder falling problem.
The preparation method of the graphene heat-insulating film provided by the invention is simple in production process and short in manufacturing period. The nano or micron particles are fixed between the graphene layers to prevent powder falling, and the defects of the heat insulation material are overcome.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic view of a microstructure of a cut surface of a graphene thermal insulation film according to the present invention;
wherein, 1-graphene, 2-aerogel and 3-cenosphere.
Detailed Description
In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.
In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features.
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
In one embodiment of the present invention, a method for preparing a graphene thermal insulation material is provided, including:
mixing the graphene carbon material dispersion system with the hollow microsphere and/or aerogel dispersion system liquid to obtain composite slurry;
defoaming, coating and drying the composite slurry to form a composite film; and
and carrying out heat treatment on the composite film to decompose functional groups on the graphene carbon material, and finally forming the graphene heat insulation film.
The graphene carbon material is graphene oxide and/or graphene. The carbon content of the graphene oxide is 48-60 wt%, and the oxygen content is 41-53 wt%. The graphene is prepared by an oxidation-reduction method. The graphene carbon material according to the present embodiment is preferably graphene oxide. Or a mixture of graphene oxide and a small amount of graphene doped in the graphene oxide, wherein the doping amount of the graphene is more than or equal to 5 according to the mass ratio of the graphene oxide to the graphene. In the graphene carbon material dispersion system, the content of the graphene carbon material and the first solvent is 3-10 wt%, for example: 3-2 wt%, 3-5 wt%, 5-6 wt%, 5-8 wt%, 6-9 wt%, 6-10 wt%, 7-9 wt%, 7.5-9 wt%, 6-8.5 wt%, 7-10 wt%, 8.5-10 wt%, etc.; preferably 8 wt%. The first solvent is selected from water and/or NMP. As an alternative to the first solvent preference, the first solvent is water and NMP according to (3-5): 1 is configured as a mixed solvent, for example: 3:1, 3.5:1, 4:1, 4.2:1, 4.5:1, 5:1, etc.; as an alternative to the first solvent, the first solvent is water and NMP in a ratio of 4: the mass ratio of 1 is configured as a mixed solvent.
The graphene carbon material system is prepared by the following method:
adding the graphene carbon material into the first solvent, and stirring uniformly by using a planetary stirrer at 300-2200 rpm. The uniform indexes are as follows: stirring until the fineness of the slurry is less than 20 mu m and the viscosity is 20000-40000 mPa.s. Generally, the above indexes can be realized by stirring for 60 +/-30 min.
The heat insulating material is hollow microspheres, or is a mixed material mixed with aerogel in the hollow microspheres, and the mixing amount of the aerogel is as follows: the mass ratio of the aerogel is more than or equal to 0.5, such as: hollow microspheres: the mass ratio of the aerogel is 0.5, 0.6, 0.8, 1, 1.5, 2, 3, 5, 6, 8, 10, 15, 20, 30, 50, 70, 90, 100, etc. As a preferred option for the heat insulating material, the heat insulating material is a hollow microsphere: the mass ratio of the aerogel is more than or equal to 1, for example: hollow microspheres: the mass ratio of the aerogel is 1, 1.2, 1.5, 1.7, 2, 3, 4, 5, 8, 10, 12, 14, 18, 20, 50, 70, 100, 200, 300, 500, and the like; as a best scheme selection of the heat insulation material, the heat insulation material is prepared by mixing the following components in percentage by weight: the mass ratio of the aerogel is 3: 2. The heat insulation material dispersion system comprises a heat insulation material and a second solvent, wherein the heat insulation material is contained in an amount of 3-15 wt%, for example: 3-5 wt%, 3-8 wt%, 3-10 wt%, 3.5-6 wt%, 4-5 wt%, 4.5-6.5 wt%, 4-6 wt%, 3.5-5.5 wt%, 4-6.5 wt%, 5-7 wt%, 6-10 wt%, 8-9 wt%, etc.; preferably 5 wt%. The second solvent is selected from water and/or NMP; as a preferable embodiment of the second solvent, the second solvent is water and NMP according to (3-5): 1 is configured as a mixed solvent, for example: 3: 1. 3.2: 1. 3.5: 1. 3.8: 1. 4: 1. 4.3: 1. 4.5: 1. 4.9: 1. 5:1, etc.; in a preferred embodiment, the second solvent is water and NMP in a ratio of 4: the mass ratio of 1 is configured as a mixed solvent.
The heat insulation material is prepared by the following method:
and adding the heat insulating material into the second solvent, and uniformly stirring to form stable suspension without sedimentation.
The particle size of the cenospheres is 1-50 μm, for example: 1-10 μm, 1-20 μm, 1-30 μm, 1-5 μm, 1-8 μm, 2-6 μm, 2-8 μm, 2-10 μm, 2-20 μm, 2-40 μm, 2-50 μm, 3-7 μm, 3-6 μm, 3-15 μm, 3-30 μm,
3.5-5.5μm、3.5-9μm、3.5-45μm、4-6μm、4-8μm、4-7μm、4-9μm、4-50μm、4-25μm、4.5-6μm、4.5-8.5μm、4.5-22μm、5-10μm、5-50μm、5-45μm、5-30μm、5-25μm、6-15μm、
8-10 μm, 8-33 μm, 10-20 μm, 20-30 μm, 15-20 μm, 18-36 μm, 30-50 μm, 35-45 μm, 40-50 μm, 45-50 μm, etc.; preferably 5 μm. The wall thickness of the air beads is 0.2-2.0 μm, for example: 0.2 to 1.5. mu.m, 0.2 to 0.5. mu.m, 0.5 to 1.2. mu.m, 0.5 to 1.5. mu.m, 0.5 to 2. mu.m, 0.6 to 1.5. mu.m, 0.6 to 1.2. mu.m, 0.8 to 2. mu.m, 0.8 to 1.5. mu.m, 0.9 to 1.1. mu.m, 0.9 to 1.5. mu.m, 0.9 to 2. mu.m, 1 to 2. mu.m, 1.2 to 2. mu.m, 0.2 to 1.5. mu.m, etc.; preferably 1.0. mu.m. In this embodiment, the cenospheres are selected from glass cenospheres and ceramic cenospheres. Other air beads may be substituted. The aerogel has a particle size of 20-100nm, for example: 20-50nm, 20-30nm, 20-25nm, 22-28nm, 25-55nm, 25-60nm, 20-80nm, 30-60nm, 30-55nm, 30-90nm, 30-75nm, 35-55nm, 35-60nm, 35-70nm, 35-80nm, 35-85nm, 40-60nm, 40-55nm, 40-52nm, 40-70nm, 40-95nm, 45-55nm, 45-60nm, 45-65nm, 45-85nm, 48-52nm, 50-60nm, 50-70nm, 50-80nm, 50-100nm, 65-80nm, 70-90nm, 75-86nm, 80-100nm, 85-90nm, 90-100nm, etc.; preferably 50 nm. In this embodiment, the aerogel is selected from silica aerogels. Other types of aerogels may be substituted.
The liquid-liquid mixing method comprises the following specific steps: adding the gas insulation material dispersion system into the graphene carbon material dispersion system according to the proportion relation that the heat insulation material accounts for 0.5-10 wt% of the graphene carbon material, and uniformly dispersing.
The proportion of the heat insulating material in the graphene carbon material is 0.5-10 wt%, for example: 0.5-9 wt%, 0.5-8 wt%, 0.5-7 wt%, 0.5-6 wt%, 0.5-5 wt%, 0.5-4 wt%, 0.5-2.5 wt%, 0.5-2 wt%, 0.5-1.5 wt%, 0.5-1.2 wt%, 0.6-6 wt%, 0.6-4.5 wt%, 0.8-1.2 wt%, 0.8-1.5 wt%, 0.8-2.5 wt%, 0.8-3 wt%, 0.8-8 wt%, 0.9-1.5 wt%, 0.9-2 wt%, 0.9-7 wt%, 0.9-9 wt%, 1-10 wt%, 1-5 wt%, 1-2 wt%, 1-3 wt%, 1.5-2.5 wt%, 2-4 wt%, 2-9 wt%, 3-5 wt%, 3.5-7 wt%, 4.5-10 wt%, 4-5 wt%, 3-10 wt%, 4.5-5 wt%, 4-10 wt%, 5 wt%, 3-10 wt%, 4.5 wt%, 4-10 wt%, 5-10 wt%, 5, 4.8-6 wt%, 5-10 wt%, 5-8 wt%, 6-9 wt%, 6-10 wt%, 8-10 wt%, etc.; preferably, the heat insulation material accounts for 1 wt% of the graphene carbon material. The dispersion is uniformly completed at a stirring speed of 300-1000rpm, for example: 300rpm, 400rpm, 450rpm, 350rpm, 500rpm, 550rpm, 600rpm, 650rpm, 700rpm, 750rpm, 800rpm, 850rpm, 900rpm, 1000rpm, and the like.
The defoaming method comprises the following steps: and (4) defoaming by continuous thin film or stirring and defoaming in vacuum. Linear continuous film defoaming
The coating is carried out by blade coating or extrusion coating the slurry on the base tape by using the base tape as a support. The coating thickness of the composite slurry is 2-3mm, for example: 2-2.5mm, 2-2.2mm, 2-2.8mm, 2.2-2.5mm, 2.2-2.7mm, 2.4-2.5mm, 2.4-2.7mm, 2.6-3mm, 2.5-2.8mm, 2.8-3mm, etc.
The temperature of the drying is room temperature to 90 ℃, for example: 25 ℃, 30 ℃, 35 ℃, 40 ℃, 50 ℃, 52 ℃, 55 ℃, 60 ℃, 63 ℃, 65 ℃, 68 ℃, 70 ℃, 75 ℃, 80 ℃, 86 ℃, 90 ℃ and the like; drying for 1-3h, for example: 1h, 1.2h, 1.5h, 2h, 2.3h, 2.5h, 2.7h, 3h, etc. In this embodiment, as a preferable scheme of the drying process conditions, the drying temperature is 50 to 90 ℃, for example: 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, 90 ℃ and the like; drying for 2 h. The thickness of the composite film formed after drying is 80-150 μm.
The temperature of the heat treatment is 100-300 ℃, for example: at a temperature of 150 ℃ at 100-; keeping the temperature constant for 2-12h at the heat treatment temperature, for example: 2-10h, 2-8h, 2-5h, 2-4h, 2.5-3.5h, 2.5-4h, 2.5-5h, 2.5-12h, 3-5h, 3-4h, 3-8h, 3-10h, 3-12h, 5-10h, 5-8h, 5-7h, 4.5-9h, 4.5-6.5h, 6-9h, 6-7.5h, 8-12h, 6-12h, 6.5-11h, 8-10.5h, 9-12h, 10-12h and the like. As a preferable scheme of the heat treatment process parameters, the temperature of the heat treatment is 200 ℃, and the constant temperature is kept for 3 hours. The heat treatment temperature is constant until the composite film expands to a thickness of 300-1000 μm, for example: 300-500 μm, 300-700 μm, 400-800 μm, 450-750 μm, 500-800 μm, 500-900 μm, 600-800 μm, 650-750 μm, 700-900 μm, 700-750 μm, 700-1000 μm, 400-1000 μm, 800-1000 μm, etc. The heat treatment is carried out at a heating rate of 0.01-2 ℃/min, the temperature is increased to the heat treatment temperature, and then the temperature is constant. The temperature rise rate may be 0.01 ℃/min, 0.02 ℃/min, 0.03 ℃/min, 0.04 ℃/min, 0.05 ℃/min, 0.08 ℃/min, 0.1 ℃/min, 0.12 ℃/min, 0.13 ℃/min, 0.15 ℃/min, 0.16 ℃/min, 0.17 ℃/min, 0.18 ℃/min, 0.2 ℃/min, 0.3 ℃/min, 0.4 ℃/min, 0.5 ℃/min, 0.6 ℃/min, 0.7 ℃/min, 0.8 ℃/min, 1.0 ℃/min, 1.2 ℃/min, 1.5 ℃/min, 1.7 ℃/min, 1.9 ℃/min, 2 ℃/min, or the like. The equipment adopted by the heat treatment can be an oven, a heating furnace, a tunnel furnace and the like.
In another embodiment of the present invention, a graphene thermal insulation film is provided, as shown in fig. 1, and includes graphene 1 and cenospheres 3 and/or aerogel 2, where the cenospheres 3 and/or aerogel 2 are distributed between layers of the graphene 1 and encapsulated in a network formed among the graphene 1 sheets. The thermal conductivity coefficient of the graphene thermal insulation film is below 0.018W/m K. The density of the graphene heat insulation film is 0.15g/cm3The following. The compressive strength of the graphene heat insulation film is greater than 10 MPa. The oxygen content of the graphene is 10-30 wt%, for example: 10-25 wt%, 10-20 wt%, 10-15 wt%, 10-12 wt%, 12-15 wt%, 12-18 wt%, 12-25 wt%, 15-20 wt%, 15-30 wt%, 15-18 wt%, 15-15.5 wt%, 17-20 wt%, 17-26 wt%, 17-30 wt%, 17.5-19 wt%, 18-30 wt%, 18.5-20 wt%, 19-26 wt%, 19-20 wt%, 19-30 wt%, 20-25 wt%, 20-22.5 wt%, 20-30 wt%, 20-28 wt%, 27-30 wt%, 27-28 wt%, 28-30 wt%, etc. According to the invention, the oxygen content of graphene in the graphene heat insulation film is finally controlled to be 10-30 wt%, when the oxygen content of graphene is less than 10 wt%, the heat insulation performance of the heat insulation film is obviously reduced, when the oxygen content of graphene is more than 30 wt%, the temperature resistance of the heat insulation film is obviously reduced, and the oxygen content of graphene in the heat insulation film is ensured to be 10-30 wt%, so that the performance of the graphene heat insulation film is optimal.
According to the graphene heat insulation film provided by the invention, graphene/graphene oxide composite aerogel or cenospheres are adopted to form graphene in-plane directional arrangement (minimum energy assembly among sheet layers, hydrogen bond and capillary pressure assembly), and aerogel nanoparticles and/or cenospheres are positioned among graphene sheet layers. The graphene has tens of thousands of layers to form an effective reflecting partition plate, and the aerogel or hollow microspheres between the layers play a role in reducing the contact of graphene sheets and increasing the thermal resistance. Gaps formed between graphene layers and the aerogel or the hollow microspheres are small, and convection of gas inside the graphene layers is blocked. The invention realizes low heat conduction, inhibits air heat convection and infrared reflection, and prepares the excellent heat insulation film. And the aerogel nanoparticles and/or the hollow microspheres are encapsulated between graphene layers, so that the product has no powder falling problem.
In order to further illustrate the essence of the present invention, some specific examples of the preparation method of the graphene thermal insulation film are listed below.
The following examples provide methods in which graphene oxide and graphene are used from element six of the state. The technical requirement indexes of the graphene oxide are as follows: the carbon content of the graphene oxide is within the range of 48-60 wt%, and the oxygen content of the graphene oxide is within the range of 41-53 wt%. The graphene is prepared by an oxidation-reduction method.
Example 1:
preparation of a graphene heat insulation film:
adding 5.40kg of graphene oxide into 174.6kg of water, and dispersing for 30min at 1000 revolutions per minute by adopting a planetary mixer, wherein the fineness of the slurry is less than 20 mu m, and the viscosity is 20000-40000 mPa.s;
0.11kg of glass cenospheres (particle size of 1 μm, wall thickness of 0.2 μm) were added to 2.2kg of water and stirred until the suspension was substantially free from sedimentation.
Dispersing the glass hollow bead suspension in the graphene oxide slurry by 300 revolutions per minute for 1 hour to obtain a composite slurry;
and (3) continuously defoaming the composite slurry by using a film, and coating the defoamed composite slurry on a base band by using the base band as a support, wherein the coating thickness is 2.0 mm. Continuous film defoaming
The base band drives the composite slurry to a drying tunnel for drying, the drying temperature of the drying tunnel is set to be 75 ℃, the drying time is 3 hours, the graphene oxide composite membrane with the thickness of 80 mu m is obtained after drying, and the graphene oxide composite membrane is separated from the base band; the graphene oxide composite membrane is placed in a heating device, the temperature is raised to 160 ℃ at the speed of 0.01 ℃/min, the graphene oxide composite membrane is treated for 10 hours at the temperature of 160 ℃, and the graphene oxide composite membrane with the thickness of 500 mu m, the thermal conductivity coefficient of 0.018W/m.K and the density of 0.13g is obtained/cm3And the compression resistance is 15 MPa.
Example 2:
preparation of a graphene heat insulation film:
adding 9.00kg of graphene oxide into 171kg of NMP, and dispersing for 30min at 800 revolutions per minute by adopting a planetary mixer, wherein the fineness of the slurry is less than 20 mu m, and the viscosity is 20000-40000 mPa.s;
adding 0.45kg of aerogel (silicon dioxide aerogel, which can be replaced by other aerogels, and the particle size of the aerogel is 20nm) into 3.00kg of NMP, and uniformly stirring until the obtained suspension does not settle basically;
adding the gel suspension into the graphene oxide slurry, and dispersing for 1h at 500 revolutions per minute to obtain a composite slurry;
performing continuous film defoaming on the composite slurry, using a base band as a support, and coating the defoamed composite slurry on the base band with the thickness of 2.5 mm;
the base band drives the composite slurry to a drying tunnel for drying, the drying temperature of the drying tunnel is 90 ℃, the drying time is 1h, a graphene oxide composite membrane with the thickness of 100 mu m is obtained after drying, and the graphene oxide composite membrane is separated from the base band;
placing the graphene oxide composite membrane in a heating device, heating to 300 ℃ at a speed of 2 ℃/min, and treating at 300 ℃ for 12h to obtain a graphene heat insulation membrane with the thickness of 800 mu m, the heat conductivity coefficient of 0.016W/m.K and the density of 0.10g/cm3And the pressure resistance is 11 MPa.
Example 3:
preparation of a graphene heat insulation film:
preparing water and NMP into a mixed solvent by adopting a mass ratio of 80: 20;
adding 14.4kg of graphene oxide into 165.6kg of mixed solvent, and dispersing for 30min at 1000 revolutions per minute by adopting a planetary mixer, wherein the fineness of the slurry is less than 20 mu m, and the viscosity is 20000-40000 mPa.s;
adding 0.15kg of a mixture of glass hollow microspheres and silicon dioxide aerogel (the mass ratio of the glass hollow microspheres to the silicon dioxide aerogel is 60:40, the particle size of the glass hollow microspheres is 5 microns, the wall thickness is 1 micron, and the particle size of the silicon dioxide aerogel is 50nm) into 2.85kg of mixed solvent, and uniformly stirring until the obtained suspension is basically not settled;
adding a turbid liquid mixed by the upper hollow microspheres and the aerogel into the graphene oxide slurry, and dispersing for 1h at 350 r/min to obtain a composite slurry;
carrying out continuous film defoaming on the composite slurry, using a base band as a support, and coating the defoamed composite slurry on the base band with the thickness of 3.0 mm;
the base band drives the composite slurry to a drying tunnel for drying, the drying temperature of the drying tunnel is 60 ℃, the drying time is 2 hours, a graphene oxide composite membrane with the thickness of 125 mu m is obtained after drying, and the graphene oxide composite membrane is separated from the base band;
placing the graphene oxide composite membrane in a heating device, heating to 200 ℃ at a speed of 1 ℃/min, and treating at 200 ℃ for 3h to obtain a graphene heat-insulating membrane with the thickness of 1000 microns, the heat conductivity coefficient of 0.015W/m.K and the density of 0.15g/cm3And the pressure resistance is 20 MPa. The microstructure schematic diagram of the graphene composite material is shown in figure 1, and the graphene composite material comprises graphene 1, cenospheres 3 and aerogel 2, wherein the cenospheres 3 and the aerogel 2 are distributed among the layers of the flaky graphene 1 and are encapsulated in a network formed among the sheets of the graphene 1.
Example 4:
preparation of a graphene heat insulation film:
preparing water and NMP into a mixed solvent by adopting a mass ratio of 100: 20;
adding 7.5kg of graphene oxide and 1.5kg of graphene into 171kg of mixed solvent, and dispersing for 90min at 300 revolutions per minute by using a planetary mixer, wherein the fineness of the slurry is less than 20 mu m, and the viscosity is 20000-40000 mPa.s;
adding 0.9kg of a mixture of ceramic hollow microspheres and silicon dioxide aerogel (the mass ratio of the ceramic hollow microspheres to the silicon dioxide aerogel is 1:1, the particle size of the glass hollow microspheres is 50 microns, the wall thickness is 2 microns, and the particle size of the silicon dioxide aerogel is 100nm) into 29.1kg of mixed solvent, and uniformly stirring until the obtained suspension is basically not settled;
dispersing the mixed suspension of the hollow microspheres and the aerogel in the mixed slurry of the graphene oxide and the graphene for 1h at 450 revolutions per minute to obtain composite slurry;
carrying out continuous film defoaming on the composite slurry, using a base band as a support, and coating the defoamed composite slurry on the base band with the thickness of 2.0 mm;
the base band drives the composite slurry to a drying tunnel for drying, the drying temperature of the drying tunnel is 50 ℃, the drying time is 2.5 hours, a graphene oxide composite membrane with the thickness of 100 mu m is obtained after drying, and the graphene oxide composite membrane is separated from the base band;
placing the graphene oxide composite membrane in a heating device, heating to 300 ℃ at a speed of 0.01 ℃/min, and treating at 300 ℃ for 3h to obtain a graphene heat insulation membrane with the thickness of 300 mu m, the heat conductivity coefficient of 0.016W/m.K and the density of 0.15g/cm3And the pressure resistance is 18.7 MPa.
Example 5:
preparation of a graphene heat insulation film:
preparing water and NMP into a mixed solvent by adopting a mass ratio of 60: 20;
adding 8.2kg of graphene oxide and 0.8kg of graphene into 171kg of mixed solvent, and dispersing for 60min at 2200 rpm by using a planetary mixer, wherein the fineness of the slurry is less than 20 mu m, and the viscosity is 20000-40000 mPa.s;
adding 0.045kg of a mixture of glass hollow microspheres and silicon dioxide aerogel (the mass ratio of the glass hollow microspheres to the silicon dioxide aerogel is 20:40, the particle size of the glass hollow microspheres is 15 microns, the wall thickness is 0.5 microns, and the particle size of the silicon dioxide aerogel is 80nm) into 0.255kg of mixed solvent, and uniformly stirring until the obtained suspension is basically not settled;
dispersing the turbid liquid mixed by the upper hollow microspheres and the aerogel in the mixed slurry of the graphene oxide and the graphene for 1h by adopting 7000 r/min to obtain composite slurry;
carrying out continuous film defoaming on the composite slurry, using a base band as a support, and coating the defoamed composite slurry on the base band with the thickness of 2.5 mm;
the base band drives the composite slurry to a drying tunnel for drying, the drying temperature of the drying tunnel is 90 ℃, the drying time is 1.5h, a graphene oxide composite membrane with the thickness of 110 mu m is obtained after drying, and the graphene oxide composite membrane is separated from the base band;
placing the graphene oxide composite membrane in a heating device, heating to 250 ℃ at a speed of 2 ℃/min, and treating for 2h at a temperature of 250 ℃ to obtain a graphene heat-insulating membrane with a thickness of 850 mu m, a heat conductivity coefficient of 0.017W/m.K and a density of 0.14g/cm3And the pressure resistance is 19.1 MPa.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (43)
1. A preparation method of a graphene heat-insulating film is characterized in that,
mixing the graphene carbon material dispersion system with the heat insulation material dispersion system liquid to obtain composite slurry;
defoaming, coating and drying the composite slurry to form a composite film; and
carrying out heat treatment on the composite film to decompose functional groups on the graphene carbon material, and finally forming a graphene heat insulation film;
the graphene carbon material dispersion system comprises a graphene carbon material and a first solvent, wherein the content of the graphene carbon material in the graphene carbon material dispersion system is 3-10 wt%, the first solvent is selected from water and/or NMP, and the graphene carbon material is graphene oxide and/or graphene;
the heat insulation material dispersion system comprises a heat insulation material and a second solvent, wherein the heat insulation material accounts for 3-15 wt%, the first solvent is selected from water and/or NMP, and the heat insulation material is hollow microspheres and/or aerogel.
2. The method for preparing the graphene thermal insulation film according to claim 1, wherein the graphene oxide contains 48-60 wt% of carbon and 41-53 wt% of oxygen.
3. The method according to claim 2, wherein the graphene is prepared by a redox method.
4. The preparation method of the graphene thermal insulation film according to claim 1, wherein the graphene carbon material is graphene oxide or a mixture of graphene oxide and a small amount of graphene, and the amount of graphene doped is not less than 5 according to the mass ratio of graphene oxide to graphene.
5. The method for preparing the graphene thermal insulation film according to claim 1, wherein the graphene carbon material in the graphene carbon material dispersion system is 8 wt%.
6. The method for preparing the graphene thermal insulation film according to claim 1, wherein the first solvent is water and NMP according to (3-5): the mass ratio of 1 is configured as a mixed solvent.
7. The method for preparing the graphene thermal insulation film according to claim 6, wherein the first solvent is water and NMP in a ratio of 4: the mass ratio of 1 is configured as a mixed solvent.
8. The preparation method of the graphene thermal insulation film according to claim 1, wherein the graphene carbon material system is prepared according to the following method:
adding the graphene carbon material into the first solvent, and stirring uniformly by using a planetary stirrer at 300-2200 rpm.
9. The preparation method of the graphene thermal insulation film according to claim 8, wherein the graphene thermal insulation film is stirred until the fineness of the slurry is less than 20 μm and the viscosity is 20000-40000 mPa.s.
10. The method for preparing the graphene thermal insulation film according to claim 9, wherein the stirring time is 60 ± 30 min.
11. The method for preparing the graphene thermal insulation film according to claim 1, wherein the thermal insulation material is cenospheres, or a mixed material in which aerogel is mixed in the cenospheres, and the mixing amount of the aerogel is as follows: the mass ratio of the aerogel is more than or equal to 0.5.
12. The method of manufacturing a graphene thermal insulation film according to claim 11, wherein when the thermal insulation material is a mixture in which aerogel is mixed in cenospheres, the mixing amount of the aerogel is as follows: the mass ratio of the aerogel is more than or equal to 1.
13. The method for preparing a graphene thermal insulation film according to claim 12, wherein the thermal insulation material is a hollow microsphere: the mass ratio of the aerogel is 3: 2.
14. The method of manufacturing a graphene thermal insulation film according to claim 1, wherein the content of the thermal insulation material in the thermal insulation material dispersion system is 5 wt%.
15. The method for preparing the graphene thermal insulation film according to claim 1, wherein the second solvent is water and NMP according to (3-5): the mass ratio of 1 is configured as a mixed solvent.
16. The method for preparing the graphene thermal insulation film according to claim 15, wherein the second solvent is water and NMP, and the ratio of the second solvent to the NMP is 4: the mass ratio of 1 is configured as a mixed solvent.
17. The method for preparing a graphene thermal insulation film according to claim 1, wherein the thermal insulation material dispersion is prepared according to the following method:
and adding the heat insulating material into the second solvent, and stirring until a stable suspension liquid is formed without sedimentation.
18. The method for preparing a graphene thermal insulation film according to claim 1, wherein the cenospheres have a particle size of 1-50 μm.
19. The method for preparing a graphene thermal insulation film according to claim 18, wherein the cenospheres have a particle size of 5 μm.
20. The method for preparing a graphene thermal insulation film according to claim 1, wherein the wall thickness of the cenospheres is 0.2-2.0 μm.
21. The method for preparing a graphene thermal insulation film according to claim 20, wherein the wall thickness of the cenospheres is 1.0 μm.
22. The method for preparing the graphene thermal insulation film according to claim 1, wherein the cenospheres are selected from glass cenospheres and ceramic cenospheres.
23. The preparation method of the graphene thermal insulation film according to claim 1, wherein the particle size of the aerogel is 20-100 nm.
24. The method for preparing the graphene thermal insulation film according to claim 23, wherein the particle size of the aerogel is 50 nm.
25. The method for preparing the graphene thermal insulation film according to claim 1, wherein the aerogel is selected from silica aerogels.
26. The preparation method of the graphene thermal insulation film according to claim 1, wherein the specific method of liquid-liquid mixing is as follows: and adding the heat-insulating material dispersion system into the graphene carbon material dispersion system according to the proportion relation that the heat-insulating material accounts for 0.5-10 wt% of the graphene carbon material, and uniformly dispersing.
27. The method of manufacturing a graphene thermal barrier film according to claim 26, wherein the thermal barrier material is 1 wt% of the graphene carbon material.
28. The method as claimed in claim 26, wherein the dispersion is performed at a stirring speed of 300-1000 rpm.
29. The preparation method of the graphene thermal insulation film according to claim 1, wherein the defoaming method comprises the following steps: and (4) defoaming by continuous thin film or stirring and defoaming in vacuum.
30. The preparation method of the graphene thermal insulation film according to claim 1, wherein the coating method comprises the following steps: the slurry is knife coated or die coated onto the base tape with the base tape as a support.
31. The preparation method of the graphene thermal insulation film according to claim 1, wherein the defoaming method comprises the following steps: the coating thickness of the composite slurry is 2-3 mm.
32. The preparation method of the graphene thermal insulation film according to claim 1, wherein the defoaming method comprises the following steps: the drying temperature is room temperature-90 ℃, and the drying time is 1-2 h.
33. The preparation method of the graphene thermal insulation film according to claim 32, wherein the drying temperature is 50-90 ℃ and the drying time is 1 hour.
34. The method for preparing the graphene thermal insulation film according to claim 1, wherein the thickness of the composite film formed after drying is 80-150 μm.
35. The method for preparing the graphene thermal insulation film according to claim 1, wherein the thermal treatment temperature is 100-300 ℃, and the constant temperature is kept for 2-12 h.
36. The preparation method of the graphene thermal insulation film according to claim 35, wherein the heat treatment temperature is 200 ℃ and is kept constant for 3 hours.
37. The method for preparing the graphene thermal insulation film according to claim 1, wherein the thermal treatment temperature is constant until the composite film expands to a thickness of 300-1000 μm.
38. The preparation method of the graphene thermal insulation film according to claim 1, wherein the temperature is raised to the thermal treatment temperature at a temperature raising rate of 0.01-2 ℃/min, and then the temperature is kept constant.
39. A graphite alkene thermal-insulated membrane which characterized in that: the graphene composite material comprises graphene and cenospheres and/or aerogel, wherein the cenospheres and/or aerogel are distributed among layers of the graphene and packaged in a network formed among graphene sheets.
40. The graphene thermal barrier film of claim 39, wherein: the thermal conductivity coefficient of the graphene thermal insulation film is below 0.018W/m.K.
41. The graphene thermal barrier film of claim 39, wherein: the density of the graphene heat insulation film is 0.15g/cm3The following.
42. The graphene thermal barrier film of claim 39, wherein: the compressive strength of the graphene heat insulation film is greater than 10 MPa.
43. The graphene thermal barrier film of claim 39, wherein: the oxygen content of the graphene is 10-30 wt%.
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