Preparation method of power battery cushioning and heat insulation pad

Abstract

The application provides a preparation method of a power battery buffer heat insulation pad, and relates to the technical field of power battery thermal management.The method comprises the following steps: preparing a gradient core material layer, and cooperatively curing the gradient core material, to prepare a power battery buffer heat insulation pad comprising a contact layer, a transition layer and a core layer; introducing Bi2Te3 topological insulator nanosheets into the core layer, and applying an axial magnetic field during the preparation process to make the Bi2Te3 topological insulator nanosheets directional arrangement, so as to form an ultralow thermal conductivity layer, effectively reduce the thermal conductivity, and significantly improve the heat insulation performance; a multifunctional structure with elastic buffering, stress dispersion and ultralow thermal conductivity characteristics is formed; the elastic buffering characteristics of the contact layer and the stress dispersion characteristics of the transition layer effectively improve the overall mechanical strength and durability; the gradient density core material is adopted, and the sound field assisted preparation technology is combined, so that the bottleneck of the traditional process is broken, and the method has significant advantages in thermal management, mechanical performance and safety performance.

Description

Technical Field

[0001] This invention relates to the field of power battery thermal management technology, and in particular to a method for preparing a power battery buffer heat insulation pad. Background Technology

[0002] With the rapid development of new energy vehicles, thermal management of power batteries has become one of the key factors affecting battery performance and safety. Batteries generate a large amount of heat during charging and discharging. If this heat cannot be dissipated effectively and in a timely manner, the battery temperature may become too high, affecting battery life, performance, and even causing thermal runaway accidents. Therefore, developing efficient buffer and insulation materials and optimizing their manufacturing processes is particularly important.

[0003] Currently, most commercially available power battery buffer insulation pads use aerogel materials as the insulation layer, but these materials have certain limitations. Specific issues mainly include:

[0004] 1. Stress concentration problem: Traditional aerogel thermal insulation pads, due to their uniform density, are prone to stress concentration when thermal expansion is uneven, which affects the thermal insulation effect and structural stability.

[0005] 2. Double-sided adhesive peeling problem: When traditional heat insulation pads use double-sided adhesive as the bonding material, peeling is prone to occur, causing product damage or performance degradation. Especially in high-temperature environments, the peel strength will decrease rapidly, affecting safety.

[0006] 3. Poor adhesion between the core material and the frame: Because it is difficult to achieve a high-strength bond between the core material and the frame, it often leads to detachment or deformation in the working environment, affecting the overall performance of the heat insulation pad.

[0007] 4. Interface layering risk caused by multi-process production: Traditional multi-process production processes have the risk of distinct and uneven interface layers, resulting in unstable overall performance. Summary of the Invention

[0008] In view of this, in order to overcome the limitations of the above-mentioned traditional technologies, the purpose of this invention is to propose a method for preparing a power battery buffer heat insulation pad, which adopts a gradient density core material and combines sound field-assisted preparation technology, thus breaking through the bottleneck of traditional processes and having significant advantages in thermal management, mechanical properties and safety performance.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] To achieve the above objectives, the present invention provides a method for preparing a power battery buffer heat insulation pad, comprising the following steps:

[0011] Step (1) Gradient core material layering preparation:

[0012] Contact layer: SiO2 sol and Al2O3 nanowires are mixed in proportion and ultrasonically dispersed, then injected into the mold through microfluidic channels to form an elastic buffer layer as the contact layer on the power battery side.

[0013] Transition layer: SiO2 sol and Al2O3 nanowires are mixed in proportion, stirred by planetary stirring and allowed to stand to defoam. After being poured into the mold, it flows naturally and forms a stress dispersion layer on the contact layer as a transition layer.

[0014] Core layer: Al2O3@shielding agent core-shell structure and Bi2Te3 topological insulator nanosheets are doped into SiO2 sol, dispersed and degassed under vacuum, and basalt fiber woven mesh is laid flat on the naturally leveled transition layer surface for infusion. The Bi2Te3 nanosheets are oriented and formed into an ultra-low thermal conductivity layer by applying an axial magnetic field simultaneously.

[0015] Step (2) Gradient core material co-curing:

[0016] By ultrasonic treatment of the interface and core regions of the gradient core material, combined with blue light for pre-curing, microbubbles are expelled and pre-polymerization is initiated; then, hot pressing is performed while applying an axial magnetic field to induce the Bi2Te3 topological insulator nanosheets to oriented along the heat flow direction, and pressure is maintained to complete the final curing, so that the Bi2Te3 topological insulator nanosheets are oriented.

[0017] As a further embodiment of the present invention, in the contact layer, SiO2 sol with a solid content of 25wt% and Al2O3 nanowires with a solid content of 15wt% are mixed at a mass ratio of 5:3 and ultrasonically dispersed at 50°C; wherein, the diameter of the Al2O3 nanowires is 30±5nm and the aspect ratio is ≥50; the power of ultrasonic dispersion is 300W and the ultrasonic dispersion time is 30min.

[0018] As a further aspect of the present invention, when injecting into the mold through the microfluidic channel, the width of the microfluidic channel is 200±5μm and the injection flow rate is 0.8ml / min.

[0019] As a further embodiment of the present invention, the pore size of the elastic buffer layer is 100±10μm, the shear force is 12Pa, and the thickness of the elastic buffer layer is 0.2mm.

[0020] As a further embodiment of the present invention, in the transition layer, SiO2 sol with a viscosity of 120 cP and Al2O3 nanowires with a viscosity of 90 cP are mixed at a mass ratio of 3:1, stirred at a speed of 800 rpm for 20 min, and then allowed to stand for defoaming for 15 min. After pouring, it naturally flows and levels to form a stress dispersion layer with a pore size of 50 ± 5 μm, wherein the thickness of the stress dispersion layer is 0.5 mm.

[0021] As a further aspect of the present invention, the Al2O3@opacifier core-shell structure doped in SiO2 sol is made by mixing Al2O3 nanowires and BiOI opacifier at a mass ratio of 3:1, deposited by magnetron sputtering, and then dispersed by mixing with SiO2 sol and Bi2Te3 topological insulator nanosheets and vacuum degassed; wherein the magnetron sputtering power is 200W, the Ar gas flow rate is 20sccm, and the substrate temperature is 80℃.

[0022] As a further aspect of the present invention, 5 wt% of Bi2Te3 topological insulator nanosheets are doped into SiO2 sol, wherein the thickness of the Bi2Te3 topological insulator nanosheets is 10±2 nm, and the nanosheets are dispersed after being pre-oriented by a 0.5T magnetic field for 10 min and then degassed under vacuum at a vacuum degree of -0.1 MPa.

[0023] As a further aspect of the present invention, basalt fiber woven mesh is laid flat on the surface of a naturally leveled transition layer, and then injected after applying a pre-compression force of 0.5 MPa; wherein the basis weight of the basalt fiber woven mesh is 80 g / m². 2 Fiber diameter 7μm, warp and weft density 12×12 fibers / cm 2 .

[0024] As a further embodiment of the present invention, the ultra-low thermal conductivity layer has a thickness of 0.1 mm, a pore size of 20 ± 2 μm, and a thermal conductivity of ≤ 0.017 W / m·K.

[0025] As a further aspect of the present invention, when preparing the gradient core material in layers, the method further includes alternating electric field control of the density gradient abrupt change between the contact layer, transition layer and core layer. During infusion, an alternating electric field of 5kV / cm and 1kHz is applied at the interlayer interface of the contact layer, transition layer and core layer, and the electrode spacing is controlled to be 10mm for 120 seconds to complete the alternating electric field control.

[0026] As a further aspect of the present invention, the interface region and core region of the gradient core material are ultrasonically treated with 40kHz ultrasound, and the sound pressure gradient during ultrasonic treatment is controlled as follows: 8W / cm² in the interface region. 2 Core region 3.5W / cm 2 .

[0027] As a further aspect of the present invention, when performing pre-curing with blue light, 405nm blue light is used, and the light intensity is controlled at 100mW / cm². 2 The light is applied at a 90° vertical angle and subjected to 300 seconds of blue light treatment, combined with ultrasonic treatment to induce polymerization and expel microbubbles.

[0028] As a further aspect of the present invention, when applying an axial magnetic field simultaneously during hot pressing, hot pressing is performed at 150°C and 10MPa, with a heating rate of 5°C / min. An axial magnetic field of 0.5T is applied simultaneously, with the magnetic field direction parallel to the heat flow direction. The pressure is maintained for 600 seconds for final curing, thereby oriented the Bi2Te3 topological insulator nanosheets.

[0029] As a further aspect of the present invention, the thermal conductivity of the oriented Bi2Te3 topological insulator nanosheets is ≤0.017W / m·K.

[0030] As a further embodiment of the present invention, after the gradient core material is co-cured, an L-shaped opening release paper is provided on the power battery side of the contact layer and double-sided adhesive is attached, with the L-shaped opening 2-6mm from the edge; a PI film with an easy-tear line is provided on the environmental side of the core layer for encapsulation, the PI film thickness is 0.03mm and the easy-tear line depth is 50% of the film thickness.

[0031] Compared with existing technologies, the method for preparing a power battery buffer heat insulation pad proposed in this invention has the following beneficial effects:

[0032] 1. This invention introduces Bi₂Te₃ topological insulator nanosheets into the core layer and applies an axial magnetic field during fabrication to orient them, thereby forming an ultra-low thermal conductivity layer. This effectively reduces the thermal conductivity and significantly improves the thermal insulation performance. Furthermore, by layering a contact layer, a transition layer, and a core layer within a gradient core material, a multifunctional structure with elastic buffering, stress dispersion, and ultra-low thermal conductivity is formed. The elastic buffering properties of the contact layer and the stress dispersion properties of the transition layer effectively enhance the overall mechanical strength and durability.

[0033] 2. This invention also employs SiO2 sol and Al2O3 nanowires, which possess high thermal stability, as the main materials. Combined with the use of basalt fiber woven mesh, the material's fire resistance and mechanical stability are improved. The encapsulation design using L-shaped release paper and a PI film with easy-tear lines enhances safety and convenience during use. The preparation process incorporates microfluidic infusion, ultrasonic dispersion, magnetron sputtering, vacuum degassing, ultrasonic treatment, blue light pre-curing, and simultaneous application of an axial magnetic field during hot pressing, ensuring the uniformity and functionality of the material's microstructure. In particular, the material's performance is further optimized by controlling the density gradient abrupt change using an alternating electric field. By precisely controlling the proportions and preparation conditions of each layer (such as the mixing ratio of SiO2 sol and Al2O3 nanowires, ultrasonic dispersion power and time, and microfluidic channel infusion flow rate), efficient material utilization and performance maximization are achieved. Detailed Implementation

[0034] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention are further described in detail below with reference to specific examples. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0036] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. Example 1

[0037] An embodiment of the present invention provides a method for preparing a power battery buffer heat insulation pad. The raw materials and equipment prepared by the method are shown in Table 1 below:

[0038] Table 1. Raw materials and equipment for the preparation method of power battery buffer heat insulation pad.

[0039] category Specifications and parameters effect raw material <![CDATA[SiO2 sol]]> Solid content 25wt%, viscosity 120cP The matrix material forms a porous structure. <![CDATA[Al2O3 nanowires]]> Diameter 30±5nm, aspect ratio ≥50, pre-dispersed in sol with a viscosity of 90cP Enhance mechanical strength and control aperture <![CDATA[Bi2Te3 nanosheets]]> Thickness 10±2nm, 5wt% doped into the core layer, pre-treated with a 0.5T magnetic field for 10min. Topological insulators, directionally blocking heat conduction Basalt Fiber Mesh <![CDATA[Grammage 80g / m 2 , fiber diameter 7μm, warp and weft density 12×12 roots / cm 2 , pre-pressure 0.5MPa]]> Increase tensile strength and prevent interlayer delamination <![CDATA[Al2O3@BiOI core-shell]]> <![CDATA[Al2O3 nanowires: BiOI light blocker = 3:1, magnetron sputtering deposition (coverage rate ≥ 95%)]]> Reflects infrared radiation (reflectivity ≥ 95%) equipment Microfluidic infusion machine Channel width 200±5μm, flow rate 0.8ml / min±0.1ml, shear force control ±1Pa Precisely control the pore size of the contact layer (100±10μm) Alternating electric field meter Output 5kV / cm, frequency 1kHz, electrode spacing 10mm±0.1mm Eliminating interlayer density abrupt changes Ultrasonic Blue Light Therapy 40kHz ultrasound (power gradient adjustable), 405nm blue light (light intensity 100mW / cm², vertical irradiation 90°). Pre-curing and defoaming initiate polymerization. Magnetic field hot press Axial magnetic field 0.5T, pressure 0-15MPa (zone control), temperature control accuracy ±1℃ <![CDATA[Final curing and oriented arrangement of Bi2Te3]]>

[0040] The method in this embodiment includes the following steps:

[0041] Step 1: Layered preparation of gradient core material:

[0042] (1) Contact layer (elastic buffer layer): SiO2 sol (solid content 25wt%) and Al2O3 nanowire sol (solid content 15wt%) are mixed at a mass ratio of 5:3 and ultrasonically dispersed at 50℃ (power 300W, time 30min); the mixture is then infused through a 200μm wide channel at a flow rate of 0.8ml / min, and the shear force is controlled at 12Pa to form a buffer layer with a pore size of 100±10μm and a thickness of 0.2mm.

[0043] (2) Transition layer (stress dispersion layer): SiO2 sol with a viscosity of 120 cP and Al2O3 sol with a viscosity of 90 cP are mixed at a mass ratio of 3:1, stirred by planetary stirring (800 rpm, 20 min), and allowed to stand for 15 min to defoam; natural leveling is used to form a transition layer with a pore size of 50 ± 5 μm and a thickness of 0.5 mm, with a compressive strength ≥ 12 MPa.

[0044] (3) Core layer (ultra-low thermal conductivity layer): 5wt% Bi2Te3 nanosheets (10±2nm thick) were oriented by a 0.5T magnetic field for 10min and dispersed in SiO2 sol; basalt fiber mesh was laid flat on the surface of the transition layer and a pre-compression force of 0.5MPa was applied; sol was injected under a vacuum of -0.1MPa, and a core layer with a pore size of 20±2μm and a thickness of 1.0mm was formed with magnetic field assistance, and the thermal conductivity was ≤0.017W / m·K.

[0045] Among them, applying an alternating electric field of 5kV / cm and 1kHz (electrode spacing 10mm) for 120 seconds at the interlayer interface eliminates abrupt changes in density gradient.

[0046] Step 2: Gradient core material co-curing:

[0047] (4) Pre-curing (ultrasound-blue light synergy): for the interface area (sound pressure 8W / cm) 2 ) and core region (3.5W / cm 2 The microbubbles were removed by ultrasonic treatment at 40 kHz; then vertically irradiated with 405 nm blue light (100 mW / cm²). 2 300 seconds, initiating pre-polymerization, synchronously stabilizing the interface with ultrasound.

[0048] (5) Final curing (hot pressing-magnetic field orientation): Step hot pressing was carried out at 150℃ and 10MPa (heating rate 5℃ / min), and the pressure was held for 600 seconds; a 0.5T axial magnetic field (parallel to the heat flow direction) was applied simultaneously to orient the Bi2Te3 nanosheets.

[0049] (6) Packaging process: On the power battery side, L-shaped opening release paper (opening distance from edge 4±0.5mm) and double-sided adhesive are bonded together, with peel force ≤0.1N / cm; on the environmental side, PI film with easy-tear line (thickness 0.03mm, line depth 50%) is wound, with tension controlled at 5±0.5N / cm (closed-loop feedback). Example 2

[0050] An embodiment of the present invention provides a method for preparing a power battery buffer heat insulation pad. The raw materials and equipment prepared by this method are shown in Table 2 below:

[0051] Table 2. Raw materials and equipment for the preparation method of power battery buffer heat insulation pad.

[0052] category Specifications and parameters effect raw material <![CDATA[SiO2 sol]]> Solid content 25wt%, viscosity 120cP (contact layer) / 90cP (transition layer) The matrix material forms a porous structure. <![CDATA[Al2O3 nanowires]]> Diameter 30±5nm, aspect ratio ≥50, pre-dispersed in sol (contact layer 15wt%, transition layer 25wt%). Enhance mechanical strength and control aperture <![CDATA[Bi2Te3 nanosheets]]> Thickness 10±2nm, 5wt% doped into the core layer, pre-treated with a 0.5T magnetic field for 10min. Topological insulators, directionally blocking heat conduction Basalt Fiber Mesh <![CDATA[Grammage 80 g / m 2 , warp and weft density 12×12 threads / cm 2 , preloading 0.5 MPa]]> Increase tensile strength and prevent interlayer delamination <![CDATA[Al2O3@BiOI core-shell]]> <![CDATA[Al2O3 nanowires: BiOI light blocker = 3:1, magnetron sputtering deposition (coverage rate ≥ 95%)]]> Reflects infrared radiation (reflectivity ≥ 95%) equipment Microfluidic infusion machine Channel width 200±5μm, flow rate 0.8ml / min±0.1ml, shear force control ±1Pa Precisely control the pore size of the contact layer (100±10μm) Alternating electric field meter Output 5kV / cm, frequency 1kHz, electrode spacing 10mm±0.1mm Eliminating interlayer density abrupt changes Ultrasonic Blue Light Therapy 40kHz ultrasound (power gradient adjustable), 405nm blue light (light intensity 100mW / cm², vertical irradiation 90°). Pre-curing and defoaming initiate polymerization. Magnetic field hot press Axial magnetic field 0.5T, pressure 0-15MPa (zone control), temperature control accuracy ±1℃ <![CDATA[Final curing and oriented alignment of Bi2Te3]]> Lamination device Hydraulic rod + compression pad structure with paddle buffer mechanism Encapsulation prevents warping; pressure uniformity ±0.05MPa.

[0053] The method includes the following steps:

[0054] Step 1: Layered preparation of gradient core material:

[0055] (1) Contact layer (elastic buffer layer): SiO2 sol (solid content 25wt%) and Al2O3 nanowire sol (solid content 15wt%) are mixed at a mass ratio of 4:3 and ultrasonically dispersed at 50℃ (power 300W, time 30min); it is then infused through a 200μm wide channel at a flow rate of 0.8ml / min, and the shear force is controlled at 12Pa to form a buffer layer with a pore size of 100±10μm and a thickness of 0.2mm.

[0056] (2) Transition layer (stress dispersion layer): SiO2 sol with a viscosity of 120 cP and Al2O3 sol with a viscosity of 90 cP are mixed at a mass ratio of 2:1, stirred by planetary stirring (800 rpm, 20 min), and allowed to stand for 15 min to defoam; natural leveling is used to form a transition layer with a pore size of 50 ± 5 μm and a thickness of 0.5 mm, with a compressive strength ≥ 12 MPa.

[0057] (3) Core layer (ultra-low thermal conductivity layer): 5wt% Bi2Te3 nanosheets (10±2nm thick) were oriented by a 0.5T magnetic field for 10min and dispersed in SiO2 sol; basalt fiber mesh was laid flat on the surface of the transition layer and a pre-compression force of 0.5MPa was applied; sol was injected under a vacuum of -0.1MPa, and a core layer with a pore size of 20±2μm and a thickness of 1.0mm was formed with magnetic field assistance, and the thermal conductivity was ≤0.017W / m·K.

[0058] Among them, applying an alternating electric field of 5kV / cm and 1kHz (electrode spacing 10mm) for 120 seconds at the interlayer interface eliminates abrupt changes in density gradient.

[0059] Step 2: Gradient core material co-curing:

[0060] (4) Pre-curing (ultrasound-blue light synergy): for the interface area (sound pressure 8W / cm) 2 ) and core region (3.5W / cm 2 The microbubbles were removed by ultrasonic treatment at 40 kHz; then vertically irradiated with 405 nm blue light (100 mW / cm²). 2 300 seconds to initiate prepolymerization, synchronous ultrasonic stabilization of the interface, microbubble removal rate ≥99%.

[0061] (5) Final curing (hot pressing-magnetic field orientation): Step hot pressing was carried out at 150℃ and 10MPa (heating rate 5℃ / min), and the pressure was held for 600 seconds; a 0.5T axial magnetic field (parallel to the heat flow direction) was applied simultaneously to orient the Bi2Te3 nanosheets, wherein the orientation angle deviation of the Bi2Te3 nanosheets was ≤5°, and the measured thermal conductivity was 0.016 W / m·K;

[0062] (6) Packaging process: On the power battery side, L-shaped opening release paper (opening distance from edge 4±0.5mm) and double-sided adhesive are bonded together, with peel force ≤0.1N / cm; on the environmental side, PI film with easy-tear line (thickness 0.03mm, line depth 50%) is wound, with tension controlled at 5±0.5N / cm (closed-loop feedback). Example 3

[0063] An embodiment of the present invention provides a method for preparing a power battery buffer heat insulation pad. The method uses the same raw materials and equipment as in Example 1, and the preparation method includes the following steps:

[0064] Step 1: Layered preparation of gradient core material:

[0065] (1) Contact layer (elastic buffer layer): SiO2 sol (solid content 25wt%) and Al2O3 nanowire sol (solid content 15wt%) are mixed at a mass ratio of 5:3. The Al2O3 nanowires have a diameter of 30±5nm and an aspect ratio of ≥50. They are ultrasonically dispersed at 50℃ (power 300W, time 30min). They are then infused through a 200μm wide channel at a flow rate of 0.8ml / min, with the shear force controlled at 12Pa, to form a buffer layer with a pore size of 100±10μm and a thickness of 0.2mm.

[0066] (2) Transition layer (stress dispersion layer): SiO2 sol with a viscosity of 120 cP and Al2O3 sol with a viscosity of 90 cP are mixed at a mass ratio of 3:1, stirred by planetary stirring (800 rpm, 20 min), and allowed to stand for 15 min to defoam; natural leveling is used to form a transition layer with a pore size of 50 ± 5 μm and a thickness of 0.5 mm, with a compressive strength ≥ 12 MPa.

[0067] (3) Core layer (ultra-low thermal conductivity layer):

[0068] Al2O3@shielding agent core-shell structure and Bi2Te3 topological insulator nanosheets were doped into SiO2 sol, dispersed and degassed under vacuum. Basalt fiber woven mesh was laid flat on the surface of the naturally leveled transition layer and infused. Bi2Te3 nanosheets were oriented and arranged by applying an axial magnetic field simultaneously to form an ultra-low thermal conductivity layer as the core layer.

[0069] Among them, the Al2O3@opacity shielding core-shell structure: Al2O3 nanowires and BiOI opacifier are mixed at a mass ratio of 3:1 and formed into a core-shell structure by magnetron sputtering (power 200W, Ar gas flow rate 20sccm, substrate temperature 80℃).

[0070] Topological insulator doping: 5 wt% Bi2Te3 topological insulator nanosheets (10 ± 2 nm thick) were doped in SiO2 sol and pre-oriented in a 0.5 T magnetic field for 10 min.

[0071] Fiber reinforcement: Basalt fiber is woven into a mesh (80g / m²). 2 Fiber diameter 7μm, warp and weft density 12×12 fibers / cm 2 Lay it flat on the surface of the transition layer and apply a pre-compression force of 0.5MPa.

[0072] Magnetic field-assisted infusion: After vacuum degassing of the sol (vacuum degree -0.1MPa), infusion is performed, and an axial magnetic field is simultaneously applied to induce the directional alignment of Bi2Te3 nanosheets, forming an ultra-low thermal conductivity layer with a pore size of 20±2μm, a thermal conductivity of ≤0.017W / m·K, and a thickness of 0.1mm.

[0073] During the infusion process, an alternating electric field of 5 kV / cm and 1 kHz (electrode spacing 10 mm) is applied to the interlayer interface for 120 seconds to eliminate abrupt changes in density gradient.

[0074] Step 2: Gradient core material co-curing:

[0075] (4) Pre-curing (ultrasound-blue light synergy): for the interface area (sound pressure 8W / cm) 2 ) and core region (3.5W / cm 2 The microbubbles were removed by ultrasonic treatment at 40 kHz; then vertically irradiated with 405 nm blue light (100 mW / cm²). 2 300 seconds, initiating pre-polymerization, synchronously stabilizing the interface with ultrasound.

[0076] (5) Final curing (hot pressing-magnetic field orientation): Step hot pressing was carried out at 150℃ and 10MPa (heating rate 5℃ / min), and the pressure was held for 600 seconds; a 0.5T axial magnetic field (parallel to the heat flow direction) was applied simultaneously to orient the Bi2Te3 nanosheets.

[0077] (6) Packaging process: On the power battery side, L-shaped opening release paper (opening distance from edge 4±0.5mm) and double-sided adhesive are bonded together, with peel force ≤0.1N / cm; on the environmental side, PI film with easy-tear line (thickness 0.03mm, line depth 50%) is wound, with tension controlled at 5±0.5N / cm (closed-loop feedback). Example 4

[0078] An embodiment of the present invention provides a method for preparing a power battery buffer heat insulation pad, the method comprising the following steps:

[0079] Step 1: Layered preparation of gradient core material:

[0080] (1) Contact layer (elastic buffer layer): SiO2 sol (solid content 28wt%) and Al2O3 nanowire sol (solid content 18wt%) are mixed at a mass ratio of 4:3. The Al2O3 nanowires have a diameter of 25±5nm and an aspect ratio ≥60. They are ultrasonically dispersed at 55℃ (0-10min: 200W; 10-30min: 400W). They are then infused through a 200μm wide channel at a flow rate of 0.8ml / min, with the shear force controlled at 12Pa, to form a buffer layer with a pore size of 100±10μm and a thickness of 0.2mm.

[0081] (2) Transition layer (stress dispersion layer): SiO2 sol with a viscosity of 120 cP and Al2O3 sol with a viscosity of 90 cP are mixed at a mass ratio of 2:1, stirred by planetary stirring (1000 rpm, 15 min), and allowed to stand for 15 min to defoam; natural leveling is used to form a transition layer with a pore size of 50 ± 5 μm and a thickness of 0.5 mm, with a compressive strength ≥ 12 MPa.

[0082] (3) Core layer (ultra-low thermal conductivity layer):

[0083] Al2O3@shielding agent core-shell structure and Bi2Te3 topological insulator nanosheets were doped into SiO2 sol, dispersed and degassed under vacuum. Basalt fiber woven mesh was laid flat on the surface of the naturally leveled transition layer and infused. Bi2Te3 nanosheets were oriented and arranged by applying an axial magnetic field simultaneously to form an ultra-low thermal conductivity layer as the core layer.

[0084] Among them, the Al2O3@opacity shielding core-shell structure: Al2O3 nanowires and BiOI opacifier are mixed at a mass ratio of 3:1 and formed into a core-shell structure by magnetron sputtering (power 200W, Ar gas flow rate 20sccm, substrate temperature 80℃).

[0085] Topological insulator doping: 5 wt% Bi2Te3 topological insulator nanosheets (10 ± 2 nm thick) were doped in SiO2 sol and pre-oriented in a 0.8 T magnetic field for 15 min.

[0086] Fiber reinforcement: Basalt fiber is woven into a mesh (80g / m²). 2 Fiber diameter 7μm, warp and weft density 12×12 fibers / cm 2 Lay it flat on the surface of the transition layer and apply a pre-compression force of 0.5MPa.

[0087] Magnetic field-assisted infusion: After vacuum degassing of the sol (vacuum degree -0.1MPa), infusion is performed, and an axial magnetic field is simultaneously applied to induce the directional alignment of Bi2Te3 nanosheets, forming an ultra-low thermal conductivity layer with a pore size of 20±2μm, a thermal conductivity of ≤0.017W / m·K, and a thickness of 0.1mm.

[0088] During the infusion process, an alternating electric field of 5 kV / cm and 1 kHz (electrode spacing 10 mm) is applied to the interlayer interface for 120 seconds to eliminate abrupt changes in density gradient.

[0089] Step 2: Gradient core material co-curing:

[0090] (4) Pre-curing (ultrasound-blue light synergy): for the interface area (sound pressure 10W / cm) 2 ) and core region (5W / cm 2 The microbubbles were removed by 60kHz ultrasonic treatment; then vertically irradiated with 385nm blue light (120mW / cm²). 2 300 seconds, initiating pre-polymerization, synchronously stabilizing the interface with ultrasound.

[0091] (5) Final curing (hot pressing-magnetic field orientation): First stage: 80℃ / 5MPa (heating rate 8℃ / min) for 200 seconds; Second stage: 170℃ / 12MPa for 400 seconds; Simultaneously apply 0.7T axial magnetic field (parallel to the heat flow direction) to orient the Bi2Te3 nanosheets.

[0092] (6) Packaging process: On the power battery side, L-shaped opening release paper (opening distance from edge 4±1mm) and double-sided adhesive are bonded together, with peel force ≤0.1N / cm; on the environmental side, a PI film with easy-tear line (thickness 0.03mm, line depth 50%) is wound, with tension controlled at 5±0.5N / cm (closed-loop feedback).

[0093] The standardized test experimental design and corresponding results of the power battery buffer heat insulation pads prepared in Examples 1 to 4 were systematically verified according to core industry standards (such as GB / T, ISO, and battery module-specific test methods):

[0094] I. Thermal insulation performance test (thermal runaway simulation).

[0095] Test equipment: heating plate (600W), thermocouple, temperature recorder;

[0096] Test standards: Thermal conductivity ≤0.020 W / m·K is acceptable, and barrier time ≥15min is excellent.

[0097] Test steps:

[0098] (1) Place the heat insulation pad between two fully charged battery cells and connect a heating plate to one side to simulate thermal runaway (constant temperature of 600℃).

[0099] (2) Monitor the temperature changes on both sides of the heat insulation pad (sampling frequency 10Hz) and record the time when adjacent battery cells reach the thermal runaway threshold (≥60℃ and heating rate ≥1℃ / s for 3s);

[0100] (3) Calculate the thermal conductivity decay rate: (initial thermal conductivity - real-time thermal conductivity) / initial thermal conductivity × 100%.

[0101] II. Mechanical performance test (cyclic extrusion).

[0102] Testing equipment: Universal testing machine (with force sensor), insulation resistance tester;

[0103] Test standard: After 2000 cycles, the thickness attenuation is ≤10%, the insulation resistance is ≥100MΩ, and the compressive strength loss is ≤15% to be considered qualified.

[0104] Test steps:

[0105] (1) Initial records: thickness (laser thickness gauge), insulation class (DC 1000V withstand voltage test), compressive strength (compression rate 2mm / min);

[0106] (2) Simulated charge and discharge cycle: The upper limit target force (corresponding to the charging expansion force) → lower limit target force (corresponding to the discharging contraction force) is applied alternately (frequency 1Hz), with an upper limit force of 10MPa and a lower limit force of 2MPa. Each cycle includes 5s of pressure holding.

[0107] (3) After every 500 cycles, the thickness attenuation rate, insulation class change and compressive strength loss are detected.

[0108] III. Interface stability test (high and low temperature cycling).

[0109] Testing equipment: High and low temperature alternating chamber (-40℃~150℃), ultrasonic scanning microscope;

[0110] Test standards: Delamination area ≤ 5% and peel strength ≥ 15 N / cm are considered excellent.

[0111] Test steps:

[0112] (1) Keep warm at -40℃ for 1 hour → keep warm at room temperature for 1 hour → keep warm at 150℃ for 1 hour is one cycle (100 times in total).

[0113] (2) The interlayer delamination area was detected by ultrasonic scanning (resolution 10 μm) after every 20 cycles;

[0114] (3) Peel strength after testing (90° peel test, rate 50 mm / min).

[0115] The performance test results for the above thermal insulation performance test, mechanical performance test, and interface stability test are shown in Table 3:

[0116] Table 3 Summary of performance test results for Examples 1 to 4

[0117]

[0118] Based on the above tests, it can be seen that in terms of thermal insulation performance advantages, Example 3 adopts an Al2O3@BiOI core-shell structure (infrared reflectivity ≥95%), combined with the magnetic field orientation of Bi2Te3 nanosheets (deviation angle ≤5°), which significantly improves the radiative heat blocking ability; Example 4 optimizes the resin crosslinking degree through two-stage hot pressing (80℃→170℃), reduces thermal expansion microcracks, and improves the thermal runaway blocking time by 39% compared with Example 1.

[0119] Regarding mechanical durability enhancement, the stepped ultrasonic dispersion (200W→400W) in Example 4 improved the uniformity of Al2O3 nanowire dispersion and reduced stress concentration points; the high pre-compression (0.8MPa) of the basalt fiber mesh enhanced the interlayer anchoring effect and suppressed fiber slippage under cyclic extrusion. After 2000 extrusions, the thickness attenuation rate was only 4.3%, which is better than the industry standard. Example 4 used 60kHz zoned ultrasonication (10W / cm in the interface region). 2 The combined alternating electric field (6kV / cm) smooths the interlayer density gradient, suppresses thermal stress delamination, reduces the delamination area to 1.8%, and achieves a peel strength of 24.2N / cm, which is 48% higher than that of Example 1.

[0120] This invention introduces Bi₂Te₃ topological insulator nanosheets into the core layer and applies an axial magnetic field during fabrication to orient them, thereby forming an ultra-low thermal conductivity layer. This effectively reduces the thermal conductivity and significantly improves the thermal insulation performance. Furthermore, by layering a contact layer, a transition layer, and a core layer within a gradient core material, a multifunctional structure with elastic buffering, stress dispersion, and ultra-low thermal conductivity is formed. The elastic buffering properties of the contact layer and the stress dispersion properties of the transition layer effectively enhance the overall mechanical strength and durability.

[0121] This invention also employs SiO2 sol and Al2O3 nanowires, which possess high thermal stability, as the main materials. Combined with the use of basalt fiber woven mesh, the material's fire resistance and mechanical stability are improved. The encapsulation design using an L-shaped release liner and a PI film with easy-tear lines enhances safety and convenience during use. The preparation process incorporates microfluidic infusion, ultrasonic dispersion, magnetron sputtering, vacuum degassing, ultrasonic treatment, blue light pre-curing, and simultaneous application of an axial magnetic field during hot pressing, ensuring the uniformity and functionality of the material's microstructure. In particular, the material's performance is further optimized by controlling the density gradient abrupt change using an alternating electric field. By precisely controlling the proportions and preparation conditions of each layer (such as the mixing ratio of SiO2 sol and Al2O3 nanowires, ultrasonic dispersion power and time, and microfluidic channel infusion flow rate), efficient material utilization and maximum performance are achieved.

[0122] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0123] It should be understood that, as used herein, the singular form "a" is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations of one or more of the associatedly listed items. The embodiment numbers disclosed above are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0124] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for preparing a power battery buffer heat insulation pad, characterized in that, The method includes the following steps: Step (1) Gradient core material layering preparation: Contact layer: SiO2 sol and Al2O3 nanowires are mixed in proportion and ultrasonically dispersed, then injected into the mold through microfluidic channels to form an elastic buffer layer as the contact layer on the power battery side. Transition layer: SiO2 sol and Al2O3 nanowires are mixed in proportion, stirred by planetary stirring and allowed to stand to defoam. After being poured into the mold, it flows naturally and forms a stress dispersion layer on the contact layer as a transition layer. Core layer: Al2O3@shielding agent core-shell structure and Bi2Te3 topological insulator nanosheets are doped into SiO2 sol, dispersed and degassed under vacuum, and basalt fiber woven mesh is laid flat on the naturally leveled transition layer surface for infusion. The Bi2Te3 nanosheets are oriented and formed into an ultra-low thermal conductivity layer by applying an axial magnetic field simultaneously. Step (2) Gradient core material co-curing: By ultrasonic treatment of the interface and core regions of the gradient core material, combined with blue light for pre-curing, microbubbles are expelled and pre-polymerization is initiated; then, hot pressing is performed while applying an axial magnetic field to induce the Bi2Te3 topological insulator nanosheets to oriented along the heat flow direction, and pressure is maintained to complete the final curing, so that the Bi2Te3 topological insulator nanosheets are oriented.

2. The method for preparing the power battery buffer heat insulation pad as described in claim 1, characterized in that, In the contact layer, SiO2 sol with a solid content of 25wt% and Al2O3 nanowires with a solid content of 15wt% are mixed at a mass ratio of 5:3 and ultrasonically dispersed at 50°C; wherein the diameter of the Al2O3 nanowires is 30±5nm and the aspect ratio is ≥50; the ultrasonic dispersion power is 300W and the ultrasonic dispersion time is 30min.

3. The method for preparing the power battery buffer heat insulation pad as described in claim 2, characterized in that, When injecting into the mold through the microfluidic channel, the width of the microfluidic channel is 200±5μm and the injection flow rate is 0.8ml / min.

4. The method for preparing the power battery buffer heat insulation pad as described in claim 3, characterized in that, The elastic buffer layer has a pore size of 100±10μm, a shear force of 12Pa, and a thickness of 0.2mm.

5. The method for preparing the power battery buffer heat insulation pad as described in claim 1, characterized in that, In the transition layer, SiO2 sol with a viscosity of 120 cP and Al2O3 nanowires with a viscosity of 90 cP are mixed at a mass ratio of 3:1, stirred at 800 rpm for 20 min, and then allowed to stand for 15 min to defoam. After pouring, it naturally flows and levels to form a stress dispersion layer with a pore size of 50 ± 5 μm, wherein the thickness of the stress dispersion layer is 0.5 mm.

6. The method for preparing the power battery buffer heat insulation pad as described in claim 5, characterized in that, The Al2O3@opacity core-shell structure doped in SiO2 sol was prepared by mixing Al2O3 nanowires and BiOI opacifier at a mass ratio of 3:1, deposited by magnetron sputtering, and then dispersed by mixing with SiO2 sol and Bi2Te3 topological insulator nanosheets and vacuum degassing. The magnetron sputtering power was 200W, the Ar gas flow rate was 20sccm, and the substrate temperature was 80℃.

7. The method for preparing the power battery buffer heat insulation pad as described in claim 6, characterized in that, 5 wt% Bi2Te3 topological insulator nanosheets were doped into SiO2 sol, wherein the thickness of the Bi2Te3 topological insulator nanosheets was 10±2 nm. After being pre-oriented by a 0.5T magnetic field for 10 min, the nanosheets were dispersed and then degassed under vacuum at a vacuum degree of -0.1 MPa.

8. The method for preparing the power battery buffer heat insulation pad as described in claim 1, characterized in that, Basalt fiber woven mesh is laid flat on the surface of the naturally leveled transition layer, and then injected after applying a pre-compression force of 0.5 MPa; wherein the basis weight of the basalt fiber woven mesh is 80 g / m². 2 Fiber diameter 7μm, warp and weft density 12×12 fibers / cm 2 .

9. The method for preparing the power battery buffer heat insulation pad as described in claim 1, characterized in that, During the preparation of the gradient core material in layers, the alternating electric field is also used to control the abrupt change in density gradient between the contact layer, transition layer and core layer. During the infusion process, an alternating electric field of 5kV / cm and 1kHz is applied to the interlayer interface of the contact layer, transition layer and core layer, and the electrode spacing is controlled to be 10mm for 120 seconds to complete the alternating electric field control.

10. The method for preparing the power battery buffer heat insulation pad as described in claim 9, characterized in that, During blue light pre-curing, 405nm blue light is used, and the light intensity is controlled at 100mW / cm². 2 The irradiation angle is 90° vertical, and blue light treatment is performed for 300 seconds. Combined with ultrasonic treatment, polymerization is initiated and microbubbles are expelled. When hot pressing is performed with an axial magnetic field applied simultaneously, hot pressing is carried out at 150℃ and 10MPa with a heating rate of 5℃ / min. A 0.5T axial magnetic field is applied simultaneously, with the magnetic field direction parallel to the heat flow direction. The pressure is held for 600 seconds for final curing, so that the Bi2Te3 topological insulator nanosheets are oriented.

Images