Nanometer thermal insulation board and preparation method and application thereof

Abstract

The invention discloses a nano thermal insulation board and a preparation method and application thereof, and relates to the technical field of nano thermal insulation board preparation, the method comprises the following steps: S1, weighing fumed silica, green silicon carbide and high silica glass fiber according to a preset mass ratio, and stirring in batches to obtain a uniformly mixed mixture; s2, after the mixture is fed into a press mold, pressure intensity is applied, the pressure is maintained for 3-5 minutes, and a pressed and formed plate blank is obtained; s3, placing the pressed and formed plate blank in a drying oven for baking to obtain a dried nano heat insulation plate; and S4, vacuum packaging is conducted on the dried nanometer heat insulation plate, so that the nanometer heat insulation plate is sealed by the packaging bag. The technical problem that it is difficult to balance between the shading requirement and the enhancement requirement of the nanometer heat insulation plate and the ultralow heat conduction performance is solved.

Description

Technical Field

[0001] This invention relates to the field of nano-insulation plate preparation technology, and in particular to a nano-insulation plate, its preparation method and application. Background Technology

[0002] With the development of new energy vehicles, electric vehicles are gradually entering the market, and the demand for increased driving range is becoming increasingly prominent. To solve this problem, higher and higher battery energy density is required. As battery energy density gradually increases, the battery cycle expansion rate also gradually increases, leading to a gradual decrease in battery safety. After being assembled into modules, the expansion force between cells increases, increasing the probability of thermal runaway and potentially causing an explosion that could endanger human lives. To prevent the risk of thermal runaway between batteries, heat insulation films are usually installed.

[0003] In existing technologies, nanoporous thermal insulation materials have become a research hotspot due to their ultra-low thermal conductivity. Traditional thermal insulation panels use fumed silica as the insulation matrix, and their strength can be improved by adding reinforcing fibers (such as ceramic fibers); infrared radiation can be suppressed by adding light-blocking agents. However, the above-mentioned thermal insulation panels still have some limitations. On the one hand, the introduction of reinforcing fibers improves mechanical properties, but excessive addition will form heat conduction pathways, leading to an increase in thermal conductivity. On the other hand, the addition of light-blocking agents (such as carbon black) can effectively suppress infrared radiation, but high addition amounts will clog pores, increase solid-phase thermal conductivity, and reduce flexibility. Therefore, due to the limitations of the above two approaches, it is difficult to achieve a balance between the light-blocking and reinforcement requirements of nano-insulation panels and their ultra-low thermal conductivity. Summary of the Invention

[0004] The purpose of this invention is to provide a nano-insulation plate, its preparation method and application, which solves the technical problem of the difficulty in balancing the requirements for light shading and reinforcement with ultra-low thermal conductivity.

[0005] To achieve this objective, the present invention adopts the following technical solution: According to a first aspect, the present invention provides a method for preparing a nano-insulating plate, comprising: Step S1: Weigh fumed silica, green silicon carbide and high silica glass fiber in a predetermined mass ratio, and obtain a uniformly mixed mixture by stirring in batches. Step S2: After the mixture is fed into the press mold, pressure is applied and held for 3-5 minutes to obtain the pressed sheet blank; Step S3: Place the pressed and shaped sheet blank in a drying oven for baking to obtain a dried nano-insulation board. Step S4: Vacuum seal the dried nano-insulation plate so that the packaging bag seals the nano-insulation plate.

[0006] Optionally, step S1 includes: Step S11: Sequentially weigh the fumed silica, the green silicon carbide, and the high-silica glass fiber according to the preset mass ratio to obtain the fumed silica, the green silicon carbide, and the high-silica glass fiber in the preset mass ratio. Step S12: Place the weighed fumed silica and green silicon carbide into a stirrer and stir the fumed silica and green silicon carbide at a first stirring speed to obtain a uniformly mixed first mixture. Step S13: Place the weighed high-silica glass fiber into another stirrer and stir the high-silica glass fiber at a second stirring speed to obtain the high-silica glass fiber that is evenly dispersed. Step S14: The uniformly dispersed high-silica glass fiber is placed into the first mixture, and the first mixture and the high-silica glass fiber are stirred again at a third stirring speed to obtain the uniformly mixed mixture.

[0007] Optionally, the mass ratio of the fumed silica, the green silicon carbide, and the high-silica glass fiber is 4:1:1, the particle size of the fumed silica is 7~40nm, the particle size of the green silicon carbide is 1~5μm, the diameter of the high-silica glass fiber is 6~9μm, and the length of the high-silica glass fiber is 3~12mm.

[0008] Optionally, the first stirring speed is 1000~3000 rpm, the second stirring speed is 200~600 rpm, and the third stirring speed is 400~800 rpm.

[0009] Optionally, step S2 includes: Step S21: The mixture is evenly spread into the cavity of the press mold. The upper and lower pressure plates of the press mold are provided with V-shaped venting micro-grooves with a depth of 0.5~1mm. The press mold is preheated to 50±5℃. Step S22: Apply gradient pressure to the press mold to obtain a formed sheet blank; Step S23: After depressurization, remove the sheet blank to ensure that the density of the sheet blank is 0.35~0.45 g / cm³. 3 .

[0010] Optionally, step S22 includes: Step S221: In the first stage, the press mold is pressurized to 5-8 MPa at a rate of 0.5-1 MPa / s and held for 30-60 seconds. Step S222: In the second stage, the pressure is increased to 12-15 MPa at a rate of 0.2-0.5 MPa / s and held for 60-90 seconds; Step S223, the third stage pressurizes to 18-20 MPa at a rate of 1-2 MPa / s and holds the pressure for 3-5 minutes.

[0011] Optionally, step S3 includes: Step S31: Place the plate blank on the ceramic porous support of the drying oven. The surface of the ceramic porous support is provided with a grid-like guide groove with a depth of 2~3mm, and the distance between two adjacent plate blanks is ≥30mm. Step S32: The plate blank is subjected to a three-stage variable temperature and humidity baking treatment; Step S33: After baking, the material is naturally cooled to below 40°C in the drying oven to obtain the dried nano-insulation board.

[0012] Optionally, step S32 includes: Step S321: The baking temperature of the first stage is set to 60±5℃, the humidity is 80±5%, the wind speed of the horizontal air supply is 0.5~1m / s, and it lasts for 2~3 hours. Step S322: The baking temperature in the second stage is set to 80±5℃ and the humidity to 40±5%. Vertical and horizontal air supply are alternately switched with a switching cycle of 10 minutes. The wind speed of both vertical and horizontal air supply is 1~2m / s and continues for 3~4 hours. Step S323: The baking temperature of the third stage is set to 105±5℃, the humidity is ≤10%, the wind speed of the negative pressure pulse air supply is 3~5m / s, and it lasts for 1~2 hours.

[0013] According to a second aspect, the present invention provides a nano-insulation panel comprising fumed silica, green silicon carbide, and high-silica glass fiber, wherein the mass ratio of the fumed silica, the green silicon carbide, and the high-silica glass fiber is 4:1:1, and the nano-insulation panel is prepared by the nano-insulation panel preparation method described in the first aspect.

[0014] According to a third aspect, the present invention provides an application of the nano-insulating plate as described in the first aspect in the preparation of an insulating film for battery cells.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a nano-insulation board, its preparation method, and its application. Through a scientifically proportioned mixture of fumed silica, green silicon carbide, and high-silica glass fiber, batch-by-batch stirring ensures thorough mixing of the components, forming a homogeneous mixture that effectively improves the mechanical properties and thermal stability of the subsequent board material. A mold-pressing process, controlling appropriate pressure and holding time, ensures a dense structure and uniform dimensions of the board blank, providing a fundamental guarantee for excellent thermal insulation performance. Drying effectively removes residual moisture from the board, solving the problem of increased thermal conductivity due to moisture content, while simultaneously improving the material's temperature resistance and service life. Vacuum sealing of the nano-insulation board isolates it from air and moisture penetration, significantly improving its storage stability and adaptability to complex environments, avoiding performance degradation caused by moisture absorption. Therefore, this invention solves the technical problem of balancing the requirements for light shading and reinforcement with ultra-low thermal conductivity in nano-insulation boards. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0018] Figure 1 This is a flowchart illustrating a method for preparing a nano-insulation plate according to an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0020] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component positioned centrally in the connection.

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] This invention provides a method for preparing a nano-insulating plate, comprising: Step S1: Weigh fumed silica, green silicon carbide, and high-silica glass fiber in a predetermined mass ratio, and obtain a uniformly mixed material by batch stirring. In this embodiment, the mass ratio of fumed silica, green silicon carbide, and high-silica glass fiber is 4:1:1. The particle size of fumed silica is 7~40nm, which is beneficial for forming a highly dispersed nanostructure framework and significantly reducing the overall thermal conductivity of the material. The particle size of green silicon carbide is 1~5μm, which enhances the material's heat radiation blocking ability without significantly improving thermal conductivity. The diameter of high-silica glass fiber is 6~9μm, and the length of high-silica glass fiber is 3~12mm. High-silica glass fiber has good flexibility and thermal stability, and can form a network framework in the plate structure, improving the overall mechanical strength and preventing shrinkage cracking.

[0023] In one embodiment, step S1 specifically includes: Step S11: Sequentially weigh the corresponding preset masses of fumed silica, green silicon carbide, and high-silica glass fiber to obtain a preset mass ratio of fumed silica, green silicon carbide, and high-silica glass fiber. By accurately weighing the mass of each component, the uniformity of the subsequent mixing process and the consistency of the final product performance are ensured, and the deviation of raw materials is avoided from having an adverse effect on thermal conductivity or mechanical properties.

[0024] Step S12: The weighed fumed silica and green silicon carbide are placed in a stirrer and stirred at a first stirring speed to obtain a uniformly mixed first mixture; wherein, the first stirring speed is 1000~3000 rpm; In this embodiment, by mixing fumed silica and green silicon carbide at the first stirring speed (1000~3000 rpm), under the action of high-speed shear force, full contact and uniform dispersion of nanoparticles and micron-sized particles are achieved, preventing agglomeration and improving the uniformity of subsequent composite and the thermal stability of the board.

[0025] Step S13: The weighed high-silica glass fiber is placed in another stirrer and stirred at a second stirring speed to obtain uniformly dispersed high-silica glass fiber; wherein, the second stirring speed is 200~600 rpm; in this embodiment, by using a second stirring speed of 200~600 rpm to pre-treat the high-silica glass fiber, it is helpful to gently disperse the high-silica glass fiber, avoid fiber breakage or clumping caused by high shear force, thereby maintaining its structural integrity and reinforcement effect.

[0026] Step S14: The uniformly dispersed high-silica glass fibers are added to the first mixture, and the first mixture and high-silica glass fibers are stirred again at a third stirring speed to obtain a uniformly mixed material. In this embodiment, the third stirring speed is 400~800 rpm. In this embodiment, adding the pre-dispersed high-silica glass fibers to the mixed silica-green silicon carbide mixture and performing composite stirring at a third stirring speed of 400~800 rpm can effectively prevent the sedimentation or segregation of nanomaterials and glass fibers, forming a uniform three-phase mixed system, and ensuring the synergistic performance of the final molded board in terms of structure, thermal conductivity, and mechanical strength.

[0027] It should be noted that, through the aforementioned multi-stage, differentiated stirring strategy and fine particle size control, the nano-insulation board prepared by this invention exhibits excellent performance in terms of thermal insulation, high-temperature resistance, mechanical properties, and material stability. It is particularly suitable for applications requiring high thermal protection in high-temperature environments, such as aerospace, electronic packaging, industrial furnace linings, and battery cells. Step S14 provides a uniform raw material distribution foundation for the subsequent pressing process in step S2, avoiding structural weaknesses caused by uneven density or fiber concentration during pressing.

[0028] Step S2 involves feeding the mixture into a press mold, applying pressure, and holding the pressure for 3-5 minutes to obtain a pressed sheet blank. In this embodiment, the press mold is a known technology and will not be described further. By feeding the mixture into a preheated press mold equipped with a venting structure, gradient pressing and controlled pressure holding are implemented to ultimately form a dense, uniformly thick, and appropriately dense sheet blank. This step not only preliminarily shapes the structural outline of the insulation board but also significantly improves its mechanical strength and stability, providing an ideal foundation for subsequent steps S3 (drying) and S4 (vacuum sealing).

[0029] In one embodiment, step S2 specifically includes: Step S21: The mixture is evenly spread into the cavity of the press mold. The upper and lower pressure plates of the press mold are both provided with V-shaped venting microgrooves with a depth of 0.5~1mm, and the press mold is preheated to 50±5℃. In this embodiment, the even spreading of the mixture ensures balanced stress distribution during pressing, avoiding thickness errors or stress concentration caused by uneven filling, and improving the consistency of the sheet dimensions. The 0.5~1mm deep V-shaped venting microgrooves help release air, moisture, or residual gas in the particle gaps during pressing, preventing bubbles, holes, or internal cracks in the sheet, and improving the internal density and thermal conductivity stability of the sheet. Preheating the press mold to 50±5℃ reduces the impact of temperature differences on the pressing effect, helps improve the material's fluidity and the stability of the pressing reaction, increases pressing efficiency and yield, and prevents material cracking due to temperature differences.

[0030] Step S22: Apply gradient pressure to the press mold to obtain the formed sheet blank. In this embodiment, by applying gradient pressure (gradually increasing pressure), the glass fiber breakage or local crushing caused by instantaneous high pressure can be avoided, thus protecting the integrity of the internal three-dimensional structure. During the compaction process, the gas and voids in the mixture are released more fully, improving the structural density and mechanical strength of the formed sheet. The rebound and springback stress of the material are reduced, and the dimensional stability is improved.

[0031] Step S23: After depressurization, remove the sheet blank to ensure its density is 0.35~0.45 g / cm³. 3 In this embodiment, the density of the sheet blank is set to 0.35~0.45 g / cm³, which is an optimized parameter range that balances thermal insulation performance and structural strength. Too low a density of the sheet blank will affect the compressive strength and service life of the insulation board; while too high a density will significantly increase thermal conductivity and reduce the thermal insulation effect. By quantitatively controlling the sheet blank, the performance stability and consistency of the formed blank are ensured, providing a substrate with controllable physical properties for subsequent processes (especially the vacuum sealing in step S4).

[0032] It should be noted that step S21, by introducing gas channels and ensuring temperature uniformity, facilitates more uniform material deformation and effective venting during subsequent pressure application, thereby improving the compaction quality of the sheet. The good compaction quality and reasonable internal pore distribution in step S22 facilitate the gradual and uniform removal of moisture from the interior during the drying process in step S3, preventing cracking and localized over-drying caused by uneven compaction. Steps S21 to S23 form a complete process chain from mold design, temperature control, pressure loading to density setting. This not only improves the structural integrity and dimensional accuracy of the sheet blank but also significantly enhances its adaptability to heat treatment and the consistency of the final product, laying a solid quality foundation for the drying in step S3 and the vacuum sealing in step S4. Through these measures, the final nano-insulation board exhibits lower thermal conductivity, higher mechanical stability, and a longer service life.

[0033] In one embodiment, step S22 specifically includes: Step S221: In the first stage, the press mold is pressurized to 5-8 MPa at a rate of 0.5-1 MPa / s and held for 30-60 seconds. In this embodiment, the first stage achieves preliminary pre-compaction, which compresses and flattens the loose mixture, and initially removes air and some free moisture from the gaps between large particles. This effectively reduces the problem of sudden movement, local crushing, or interlayer separation of the raw materials in the subsequent high-pressure stage. Holding the pressure for 30-60 seconds helps to stabilize the material position and form a uniform stress-bearing starting surface, providing a structural basis for the subsequent pressurization stage.

[0034] In step S222, the second stage pressurizes the material to 12-15 MPa at a rate of 0.2-0.5 MPa / s and holds the pressure for 60-90 seconds. In this embodiment, the pressure rate in the second stage is lower than that in the first stage, which allows the internal structure to undergo dense rearrangement under a more gradual increase in pressure, which is beneficial for the formation of a stable synergistic effect between nanoparticles and glass fibers. In the medium-pressure stage, it helps to promote the infiltration of fumed silica particles into the gaps in the glass fibers, enhances the filling capacity, forms a continuous thermally conductive blocking path, and improves the thermal insulation performance. The extended holding time further stabilizes the structure of the compressed material, avoids compression rebound or structural springback problems, and improves the final dimensional accuracy.

[0035] Step S223: In the third stage, the pressure is increased to 18-20 MPa at a rate of 1-2 MPa / s and held for 3-5 minutes. In this embodiment, the third stage achieves final high-pressure shaping, ensuring that the material reaches the target density (0.35-0.45 g / cm³), while simultaneously compacting the internal microporous structure. Under high pressure, the glass fibers and nanoparticles form a physical bond and interlock, improving mechanical properties and the structural stability of the plate. The long-term pressure holding (3-5 minutes) can fully release residual gas or minor stress, effectively suppressing microcracks or later deformation, and improving the long-term stability of the material.

[0036] It should be noted that the three-stage pressing strategy, from rapid low-pressure compaction to slow degassing and structural rearrangement under medium pressure, and finally to high-pressure densification and shaping, forms a gradient stress management mechanism. This effectively avoids problems such as fiber breakage, interlayer slippage of raw materials, and material fragmentation. While ensuring fiber continuity, it achieves high-density pressing, improving the material's thermal resistance, compressive strength, and shape retention. It provides a well-structured and structurally stable substrate for subsequent drying, preventing thermal stress concentration or substrate deformation during the drying process. The dense and uniform substrate structure allows for more even moisture release during the drying process in step S3, effectively preventing edge cracking or central moisture accumulation. The substrate is less prone to moisture absorption or deformation, providing an ideal geometric and physical basis for vacuum sealing in step S4. The particle intercalation network formed under high pressure exhibits excellent shape retention and compressive strength after sealing, enhancing the stability and reliability of the nano-insulation board during long-term use. The three-stage pressing process design of steps S221 to S223 is the key to ensuring that the nano-insulation plate of the present invention has high density, low thermal conductivity, high mechanical stability and good dimensional accuracy, effectively enhancing the controllability of the preparation process and its industrial practical value.

[0037] To further suppress the structural springback problem of the sheet metal blank, step S2 further includes the following between steps S22 and S23: Step S2a: While maintaining the first pressure of the press mold, heat the press mold to 70~90℃ and heat-stabilize it for 3~5 minutes. In this embodiment, the first pressure ranges from 3~6MPa, and can be 4MPa or 5MPa. Utilizing the viscous properties of fumed silica and the thermal softening behavior of glass fiber, a slight bond is formed at the raw material interface, temporarily locking the internal skeleton structure and preventing structural damage caused by rebound after pressure release. By using the critical soft adhesion between nano-silica and glass fiber at medium temperature, a resin-free pre-curing mechanism is formed, achieving structural stability while maintaining the high heat resistance of the inorganic material system. This step strengthens the material structure through the synergistic effect of temperature and pressure. Excessive pressure will affect the density and fiber distribution of the board, while insufficient pressure cannot effectively prevent material rebound.

[0038] Step S2b involves structurally limiting the press mold to prevent the pressure plate from moving. In this embodiment, a limiting post or limiting ring is added inside the press mold. Under pressure holding conditions, the mold is mechanically limited and fixed, preventing the pressure plate from moving upwards, thus controlling the finished product thickness fluctuation within ±0.1mm. The thickness of the limiting post or limiting ring can be designed according to the size of the press mold. By setting the limiting post or limiting ring, it is possible to prevent the pressure plate from rebounding too quickly or the internal elastic rebound from causing the thickness of the sheet metal blank to increase.

[0039] Step S2c involves vacuuming the press mold while maintaining its second pressure. In this embodiment, the second pressure ranges from 0.5 to 2 MPa, and can be 0.5 MPa, 1 MPa, or 2 MPa. This pressure range is sufficient to maintain uniform pressure within the mold during vacuum extraction, thereby preventing structural instability or springback due to sudden pressure drops. During heating and stabilization, an external vacuum system known in the art is connected via a V-shaped venting groove to expel residual gas or micro-water from the press mold cavity through micro-vacuum extraction, preventing blistering or internal cracking of the sheet metal blank during the drying stage in subsequent step S3. While conventional pressure evacuation only occurs before molding, this invention performs micro-vacuum extraction after molding without depressurization, which is more beneficial for the internal stability of the sheet metal blank.

[0040] Step S3 involves placing the pressed sheet blank in a drying oven for baking to obtain the dried nano-insulation board. In this embodiment, the drying oven is a well-known device in the art and will not be described in detail here. In this embodiment, this step, by controlling the ambient temperature and humidity parameters and employing a scientific bracket structure and a staged baking strategy, systematically removes moisture from the pressed sheet blank, significantly improving the structural stability and thermal performance of the nano-insulation board. The entire drying process balances stress release, structural protection, and optimization of moisture diffusion channels, effectively preventing problems such as cracking, deformation, and moisture reabsorption.

[0041] In one embodiment, step S3 specifically includes: Step S31: Place the plate blank on the ceramic porous support of the drying oven. The surface of the ceramic porous support is provided with a grid-like guide groove with a depth of 2-3mm, and the distance between two adjacent plate blanks is ≥30mm. In this embodiment, since the ceramic porous support has good high-temperature stability and air permeability, it can improve the hot air circulation efficiency and prevent uneven drying due to insufficient heat exchange at the bottom. By setting the grid-like guide groove (2-3mm), it can promote the rapid diffusion and discharge of heat flow and water vapor at the bottom and sides of the plate, improving drying efficiency and uniformity. Since the distance between the plates is not less than 30mm, it can prevent heat interference, heat accumulation and steam backflow, and ensure that each plate is dried in an independent air circulation area, which is beneficial to control the consistency of large-scale production in multiple batches.

[0042] Step S32 involves a three-stage variable temperature and humidity baking process on the sheet metal blank. In this embodiment, the three-stage variable temperature control effectively matches the moisture diffusion rate with the material shrinkage strain change process, achieving slow moisture release and low-stress drying. This significantly reduces volumetric stress caused by changes in internal porosity, minimizing the risk of cracking and deformation. The staged temperature control process helps to create a gradual stress release path, providing a foundation for structural stability during the cooling stage.

[0043] Step S33: After baking, the material is naturally cooled to below 40°C in a drying oven to obtain the dried nano-insulation board. In this embodiment, natural slow cooling avoids thermal stress concentration and microcrack formation caused by rapid cooling; when the temperature is cooled to below 40°C, the board reaches a safe temperature for removal from the oven, avoiding thermal damage or moisture absorption during subsequent handling and packaging; the stable structural state helps maintain the pressing density and dimensional accuracy, providing an ideal condition for the vacuum packaging in the subsequent step S4.

[0044] It should be noted that step S3 forms an organically integrated drying system, encompassing structural support, airflow organization, temperature and humidity control, and stress management. This effectively achieves graded moisture release and structural stabilization, improving the thermal stability, shape retention, and long-term performance of the final nano-insulation board. The dried board exhibits uniform pores and a dense structure, crucial for achieving high performance and low thermal conductivity. The significantly reduced moisture content of the board lowers the risk of internal moisture absorption and expansion or increased thermal conductivity after encapsulation. Cooling to room temperature prevents damage to the heat-sealing material or the generation of internal pressure during encapsulation. The stable shape and accurate dimensions of the board facilitate efficient and tight packaging sealing, improving sealing performance and product appearance consistency. Steps S31 to S33 constitute a scientifically sound drying system. Through the integration of optimized support, temperature and humidity control, and natural cooling, this system not only effectively improves the drying quality and physical properties of the nano-insulation board but also provides a stable and controllable technical foundation for the subsequent vacuum encapsulation process in step S4.

[0045] In one embodiment, step S32 specifically includes: Step S321: The baking temperature for the first stage is set to 60±5℃, the humidity to 80±5%, and the horizontal airflow velocity to 0.5~1m / s, lasting for 2~3 hours. In this embodiment, the relatively low temperature of 60±5℃ helps to avoid excessive thermal stress on the surface and inside, thereby reducing the risk of surface cracks or structural damage. The higher humidity of 80±5% allows for the slow evaporation of moisture inside the board, preventing cracking due to excessive moisture loss. The gentle airflow velocity of 0.5~1m / s maintains air circulation, avoiding physical impact on the board surface from excessively high airflow, while also helping moisture evaporate evenly. The 2~3-hour duration ensures that moisture is gradually released from the surface of the board, preparing for the higher temperature treatment in subsequent stages.

[0046] Step S322: The baking temperature for the second stage is set to 80±5℃, slightly increasing the temperature based on the first stage to further promote moisture evaporation, reduce residual moisture inside the board, and avoid excessive drying or deformation caused by excessively high temperatures. The humidity is 40±5%. In this stage, the humidity is reduced to further accelerate moisture evaporation, while avoiding thermal stress caused by rapid moisture loss due to excessively low humidity. Vertical and horizontal air supply are alternately switched at a cycle of 10 minutes. The alternating air supply mode ensures that moisture is evenly distributed on the surface and inner layers of the board, avoiding localized drying that is too fast or too slow due to unidirectional airflow. The air velocity for both vertical and horizontal air supply is 1~2m / s. The moderate air velocity ensures uniform water vapor flow and airflow distribution, avoiding excessively high local humidity caused by water vapor retention, which can lead to deformation or cracks. This process continues for 3~4 hours. This duration ensures that the moisture on the surface and inside of the board can be stably removed, reaching a state suitable for rapid dehydration in the third stage.

[0047] Step S323: The baking temperature for the third stage is set at 105±5℃. This higher temperature effectively removes residual moisture, ensuring complete removal of moisture from the board's interior while preventing moisture from affecting thermal conductivity and material properties. Humidity is ≤10%, ensuring thorough moisture removal and preventing any residual moisture from affecting the board's physical properties. The negative pressure pulse airflow velocity is 3~5m / s. This accelerates moisture evaporation in a short time, ensuring rapid and uniform removal of moisture from the inner layers of the board, effectively preventing excessive internal stress caused by moisture accumulation. This process continues for 1~2 hours; appropriate time control ensures complete moisture evaporation, allowing the board to reach a stable, dry state. The pulsed negative pressure extracts trapped water vapor from the gaps between the green silicon carbide particles, preventing high-temperature oxidation of the particles. Step S323 uses a pulse with a negative pressure of -5~-10kPa and a frequency of 5Hz.

[0048] It should be noted that the temperature and humidity control in step S321 ensures that surface moisture removal is relatively slow, creating favorable conditions for moisture to diffuse from deep within the board during further heating, and preventing stress concentration in the material due to excessive temperature differences in the subsequent baking stage. The second stage of baking in step S322 effectively removes most of the moisture, laying the foundation for rapid moisture evaporation under high temperature and humidity conditions; alternating airflow ensures uniform moisture diffusion, helping to maintain the structural stability of the board and preventing cracking due to uneven drying. The third stage of baking in step S323 completely removes moisture from the board, preventing moisture absorption problems during subsequent packaging and reducing dimensional changes caused by moisture expansion or absorption; a thoroughly dried board structure is more stable, helping to improve packaging sealing and preventing packaging materials from becoming damp or deformed.

[0049] It should also be noted that the precise control of the three-stage baking process not only effectively removes moisture from the board but also avoids stress concentration or structural cracks caused by excessively rapid or slow moisture loss. This controlled process ensures the uniformity, thermal stability, and dimensional accuracy of the nano-insulation board, providing a high-quality substrate for subsequent vacuum sealing. Temperature and humidity control and airflow adjustment at each stage allow the board to maximize its excellent thermal insulation performance while maintaining structural stability. The baking process in step S32 thoroughly removes moisture from the board, ensuring that performance degradation is not caused by moisture penetration during sealing; it maintains the stability of the board's shape, reducing deformation and cracking during drying, providing an ideal shape and dimensions for vacuum sealing in step S4; it improves the stability of the sealed product, prevents changes in physical properties due to moisture content, and enhances the overall lifespan and reliability of the product.

[0050] Step S4 involves vacuum sealing the dried nano-insulation board to enclose it in a packaging bag. In this embodiment, after the dried board is placed into the packaging bag, the bag is heat-sealed on three sides. Then, a vacuum pump is connected to create a vacuum, and after holding the pressure for 10-30 seconds, the last side is quickly heat-sealed to achieve vacuum sealing of the nano-insulation board. The heat-sealing process is well-known in the art and will not be described in detail here.

[0051] It should be noted that the high-temperature heat-sealing process seals three sides of the packaging bag, effectively preventing external air, moisture, and impurities from entering, creating a stable environment for subsequent vacuum extraction. A vacuum pump is then used to extract the air from the packaging bag, achieving a low vacuum level (depending on product requirements), effectively isolating external air and moisture, further stabilizing the physical properties of the nano-insulation board. Holding the pressure for 10-30 seconds ensures that all gas inside the packaging bag is completely expelled under vacuum, guaranteeing high sealing and isolation during packaging. This moderate holding time effectively eliminates air while avoiding negative impacts on the material from excessively long periods. This vacuum sealing process ensures that the nano-insulation board effectively isolates itself from external moisture and air after packaging, maintaining stable thermal insulation performance during storage and transportation. Vacuum sealing not only extends the material's shelf life but also enhances the product's compressive strength and durability, preventing external contaminants from affecting the board's quality. This process significantly improves the long-term performance and mechanical properties of the board, providing end users with high-quality, long-lasting, and stable nano-insulation board products.

[0052] Working Principle: This invention provides a nano-insulation board, its preparation method, and its application. Through a scientifically proportioned mixture of fumed silica, green silicon carbide, and high-silica glass fiber, batch-by-batch stirring ensures thorough mixing of the components, forming a homogeneous mixture that effectively improves the mechanical properties and thermal stability of the subsequent board material. A mold-pressing process, controlling appropriate pressure and holding time, ensures a dense structure and uniform dimensions of the board blank, providing a fundamental guarantee for excellent thermal insulation performance. Drying effectively removes residual moisture from the board, solving the problem of increased thermal conductivity due to moisture content, while simultaneously improving the material's temperature resistance and service life. Vacuum sealing of the nano-insulation board isolates it from air and moisture penetration, significantly improving its storage stability and adaptability to complex environments, avoiding performance degradation caused by moisture absorption. Therefore, this invention solves the technical problem of balancing the requirements for light shading and reinforcement with ultra-low thermal conductivity in nano-insulation boards.

[0053] This invention also provides a nano-insulation board, comprising fumed silica, green silicon carbide and high-silica glass fiber, wherein the mass ratio of fumed silica, green silicon carbide and high-silica glass fiber is 4:1:1, and the nano-insulation board is prepared by the above-described method.

[0054] The present invention also provides an application of the above-described nano heat insulation plate in the preparation of heat insulation film for battery cells.

[0055] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a nano-insulating plate, characterized in that, include: Step S1: Weigh fumed silica, green silicon carbide and high silica glass fiber in a predetermined mass ratio, and obtain a uniformly mixed mixture by stirring in batches. Step S2: After the mixture is fed into the press mold, pressure is applied and held for 3-5 minutes to obtain the pressed sheet blank; Step S3: Place the pressed and shaped sheet blank in a drying oven for baking to obtain a dried nano-insulation board. Step S4: Vacuum seal the dried nano-insulation plate so that the packaging bag seals the nano-insulation plate.

2. The method for preparing the nano-insulation plate according to claim 1, characterized in that, Step S1 includes: Step S11: Sequentially weigh the fumed silica, the green silicon carbide, and the high-silica glass fiber according to the preset mass ratio to obtain the fumed silica, the green silicon carbide, and the high-silica glass fiber in the preset mass ratio. Step S12: Place the weighed fumed silica and green silicon carbide into a stirrer and stir the fumed silica and green silicon carbide at a first stirring speed to obtain a uniformly mixed first mixture. Step S13: Place the weighed high-silica glass fiber into another stirrer and stir the high-silica glass fiber at a second stirring speed to obtain the high-silica glass fiber that is evenly dispersed. Step S14: The uniformly dispersed high-silica glass fiber is placed into the first mixture, and the first mixture and the high-silica glass fiber are stirred again at a third stirring speed to obtain the uniformly mixed mixture.

3. The method for preparing the nano-insulating plate according to claim 1 or 2, characterized in that, The mass ratio of the fumed silica, the green silicon carbide, and the high-silica glass fiber is 4:1:

1. The particle size of the fumed silica is 7~40nm, the particle size of the green silicon carbide is 1~5μm, the diameter of the high-silica glass fiber is 6~9μm, and the length of the high-silica glass fiber is 3~12mm.

4. The method for preparing the nano-insulation plate according to claim 2, characterized in that, The first stirring speed is 1000~3000 rpm, the second stirring speed is 200~600 rpm, and the third stirring speed is 400~800 rpm.

5. The method for preparing the nano-insulation plate according to claim 1, characterized in that, Step S2 includes: Step S21: The mixture is evenly spread into the cavity of the press mold. The upper and lower pressure plates of the press mold are provided with V-shaped venting micro-grooves with a depth of 0.5~1mm. The press mold is preheated to 50±5℃. Step S22: Apply gradient pressure to the press mold to obtain a formed sheet blank; Step S23: After depressurization, remove the sheet blank to ensure that the density of the sheet blank is 0.35~0.45 g / cm³. 3 .

6. The method for preparing the nano-insulation plate according to claim 5, characterized in that, Step S22 includes: Step S221: In the first stage, the press mold is pressurized to 5-8 MPa at a rate of 0.5-1 MPa / s and held for 30-60 seconds. Step S222: In the second stage, the pressure is increased to 12-15 MPa at a rate of 0.2-0.5 MPa / s and held for 60-90 seconds; Step S223, the third stage pressurizes to 18-20 MPa at a rate of 1-2 MPa / s and holds the pressure for 3-5 minutes.

7. The method for preparing the nano-insulation plate according to claim 1, characterized in that, Step S3 includes: Step S31: Place the plate blank on the ceramic porous support of the drying oven. The surface of the ceramic porous support is provided with a grid-like guide groove with a depth of 2~3mm, and the distance between two adjacent plate blanks is ≥30mm. Step S32: The plate blank is subjected to a three-stage variable temperature and humidity baking treatment; Step S33: After baking, the material is naturally cooled to below 40°C in the drying oven to obtain the dried nano-insulation board.

8. The method for preparing the nano-insulation plate according to claim 7, characterized in that, Step S32 includes: Step S321: The baking temperature of the first stage is set to 60±5℃, the humidity is 80±5%, the wind speed of the horizontal air supply is 0.5~1m / s, and it lasts for 2~3 hours. Step S322: The baking temperature in the second stage is set to 80±5℃ and the humidity to 40±5%. Vertical and horizontal air supply are alternately switched with a switching cycle of 10 minutes. The wind speed of both vertical and horizontal air supply is 1~2m / s and continues for 3~4 hours. Step S323: The baking temperature of the third stage is set to 105±5℃, the humidity is ≤10%, the wind speed of the negative pressure pulse air supply is 3~5m / s, and it lasts for 1~2 hours.

9. A nano-insulation panel, characterized in that, The nano-insulation board comprises fumed silica, green silicon carbide, and high-silica glass fiber, wherein the mass ratio of the fumed silica, the green silicon carbide, and the high-silica glass fiber is 4:1:1, and the nano-insulation board is prepared by the method for preparing a nano-insulation board as described in any one of claims 1 to 8.

10. The application of the nano-insulating plate as described in claim 9 in the preparation of the heat insulation film for battery cells.

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