Thermal insulation layer, preparation method thereof and battery

Abstract

The invention provides a thermal insulation layer, a preparation method thereof and a battery, and belongs to the technical field of batteries, the thermal insulation layer comprises micro-nano ceramic particles, micro-nano aerogel particles, layered micro-nano sheets, a microencapsulated phase change material and an interfacial compatibility enhancer; wherein the surface of the micro-nano ceramic particle contains a first active group, the surface of the layered micro-nano sheet contains a second active group, the surface of the microencapsulation phase change material contains a third active group, and the interface compatibility enhancer contains a fourth active group. At least two of the micro-nano ceramic particles, the micro-nano aerogel particles, the layered micro-nano sheets and the microencapsulated phase change material are mutually bonded by the interfacial compatibility enhancer. The micro-nano ceramic particles, the micro-nano aerogel particles, the layered micro-nano sheets and the microencapsulated phase change material are bonded, so that the mechanical strength, the wear resistance and the crack resistance of the heat insulation layer are improved; a specific composite structure formed by different components effectively hinders heat conduction, and the heat insulation effect is improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to a heat insulation layer and its preparation method, and a battery. Background Technology

[0002] With the rapid development of the new energy vehicle industry, power batteries have become a research hotspot. As the requirements for high energy density and rapid charge / discharge of lithium-ion batteries increase, the thermal management needs of lithium-ion batteries are becoming increasingly stringent. Simultaneously, batteries are susceptible to high-temperature environments during use, which can affect their performance and lifespan. Therefore, research on thermal insulation layers has received widespread attention. Existing thermal insulation materials struggle to meet the following key requirements: Currently, the heat insulation layers of power batteries mainly employ traditional technologies such as polymer heat insulation films, ceramic coatings, single nanomaterial coatings, and aerogel materials. These heat insulation layers have the following drawbacks: (1) limited heat insulation performance, unable to effectively block heat conduction, and difficult to prevent thermal runaway; (2) poor mechanical stability, easily leading to cracking or detachment of the heat insulation layer due to thermal expansion and contraction or mechanical stress; (3) poor interfacial bonding, with weak interfaces between materials, affecting the overall structural stability and durability. Therefore, the existing heat insulation layers have relatively poor heat insulation performance and mechanical strength. Summary of the Invention

[0003] This application provides a heat insulation layer and its preparation method, as well as a battery, aiming to solve the problem that the heat insulation performance and mechanical strength of existing heat insulation layers are relatively poor.

[0004] In a first aspect, this application provides a heat insulation layer comprising micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, microencapsulated phase change material, and an interface compatibility enhancer; wherein the surface of the micro / nano ceramic particles contains a first active group, the surface of the layered micro / nano sheets contains a second active group, the surface of the microencapsulated phase change material contains a third active group, and the interface compatibility enhancer contains a fourth active group, wherein the interface compatibility enhancer bonds at least two of the micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change material to each other.

[0005] The micro / nano ceramic particles of this application have a first active group on their surface, the layered micro / nano sheets have a second active group on their surface, the microencapsulated phase change material has a third active group on its surface, and the interface compatibility enhancer has a fourth active group. The first, second, third, and fourth active groups can bond to each other or undergo chemical reactions to couple with each other, thereby making the micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change material in the heat insulation layer uniformly distributed and strongly bonded, avoiding particle agglomeration, and forming a heat insulation layer with a specific microstructure. The resulting heat insulation layer has excellent mechanical strength, wear resistance, and crack resistance. Micro- and nano-aerogel particles possess extremely low thermal conductivity and a nanoscale porous structure, enabling them to form a multi-level porous thermal insulation framework with micro- and nano-ceramic particles. Layered micro- and nano-sheets can construct a continuous sheet-like support network within the insulation layer, improving its mechanical properties. Simultaneously, the layered micro- and nano-sheets can overlap to form a "maze-like" thermal conduction barrier, extending the heat transfer path and reducing the thermal conductivity of the insulation layer. In other words, the specific composite structure formed by micro- and nano-ceramic particles, micro- and nano-aerogel particles, and layered micro- and nano-sheets effectively hinders heat conduction, significantly reducing thermal conductivity and improving insulation performance. Microencapsulated phase change materials can absorb heat and undergo phase change within a certain temperature range, enabling temperature-responsive thermal management and intelligent temperature control. Interface compatibility enhancers not only improve the bonding force between micro- and nano-ceramic particles, micro- and nano-aerogel particles, layered micro- and nano-sheets, and microencapsulated phase change materials, thereby enhancing the mechanical properties of the insulation layer, but also improve its flexibility, preventing cracking and allowing the insulation layer to better adapt to the internal structure of the battery.

[0006] Optionally, micro-nano ceramic particles account for 40% to 50% of the mass of the insulation layer; and / or, micro-nano aerogel particles account for 5% to 10% of the mass of the insulation layer; and / or, layered micro-nano sheets account for 8% to 12% of the mass of the insulation layer; and / or, microencapsulated phase change materials account for 12% to 18% of the mass of the insulation layer; and / or, interfacial compatibility enhancers account for 2% to 5% of the mass of the insulation layer.

[0007] The relatively high proportion of micro / nano ceramic particles in this application can construct a continuous basic thermal insulation framework for the thermal insulation layer, while also endowing the thermal insulation layer with certain mechanical strength and high temperature resistance. An appropriate amount of micro / nano aerogel particles can form a suitable amount of nanoscale pores in the thermal insulation layer, thereby effectively suppressing heat convection and avoiding its weakening of the mechanical properties of the thermal insulation layer. An appropriate amount of layered micro / nano sheets can effectively improve the mechanical properties of the thermal insulation layer while forming a small amount of heat conduction channels in the thermal insulation layer, reducing its impact on the thermal insulation performance. An appropriate amount of microencapsulated phase change material can enable the thermal insulation layer to dynamically regulate temperature changes within a certain range. An appropriate amount of micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change material can effectively improve the interfacial bonding force between the micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change material, and reduce their impact on the thermal insulation performance of the thermal insulation layer.

[0008] Optionally, the D50 particle size of the micro / nano ceramic particles is 10 nm to 50 nm; and / or, the D50 particle size of the micro / nano aerogel particles is 5 nm to 20 nm; and / or, the sheet size of the layered micro / nano sheets is 1 μm to 3 μm; and / or, the D50 particle size of the microencapsulated phase change material is 2 μm to 8 μm.

[0009] The micro-nano ceramic particles of suitable size in this application can uniformly fill the interlayer gaps of layered micro-nano sheets, effectively blocking the heat conduction channels formed between the layered micro-nano sheets and improving the heat insulation performance of the insulation layer; the micro-nano aerogel particles of suitable size can uniformly and fully fill the gaps between micro-nano ceramic particles, achieving gradient dense stacking and forming a relatively dense multi-level porous heat insulation skeleton, further improving the heat insulation performance of the insulation layer; the layered micro-nano sheets of suitable size form a continuous support network while avoiding their stacking, forming a heat insulation layer with both mechanical strength and flexibility; the microencapsulated phase change material of suitable size can accommodate sufficient phase change material, reducing the damage to the heat insulation layer structure caused by the phase change process of the phase change material.

[0010] Optionally, the insulation layer includes an insulation body layer and a hydrophobic layer disposed on at least one side surface of the insulation body layer; and / or, the thickness of the insulation layer is 20 μm to 50 μm.

[0011] This application provides a hydrophobic layer on at least one side of the heat insulation body layer, making the heat insulation layer hydrophobic and significantly reducing the wetting and adsorption capacity of water vapor, thereby enabling the heat insulation layer to have an anti-condensation function; and by setting the thickness to 20μm~50μm, while ensuring that it has good heat insulation and mechanical properties, it reduces its impact on battery energy density.

[0012] Optionally, the first active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group; and / or, the second active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group; and / or, the third active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group; and / or, the fourth active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group.

[0013] The oxygen-containing, nitrogen-containing, and sulfur-containing active groups approved in this application have high activity. These groups can form covalent bonds through hydrogen bonding or chemical reactions, thereby improving the interfacial bonding force between micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, microencapsulated phase change materials, and interfacial compatibility enhancers, and improving the mechanical properties of the thermal insulation layer.

[0014] Optionally, the micro / nano ceramic particles include at least one of micro / nano alumina particles, micro / nano zirconia particles, micro / nano silicon nitride particles, and micro / nano aluminum titanate particles; and / or, the micro / nano aerogel particles have a porosity higher than 80%, and the micro / nano aerogel particles include at least one of micro / nano silica aerogel particles, micro / nano alumina aerogel particles, micro / nano silicon carbide aerogel particles, micro / nano silica-micro / nano alumina composite aerogel, and polyurethane-micro / nano silica composite aerogel; and / or, the layered micro / nano sheets include graphene oxide micro / nano sheets, boron nitride micro / nano sheets, and so on. The material comprises at least one of graphene oxide micro / nanosheets, mica micro / nanosheets, and montmorillonite micro / nanosheets, wherein the oxygen-containing functional group content of the graphene oxide micro / nanosheets is ≥30 at%; and / or, the microencapsulated phase change material comprises a core layer and a coating layer, wherein the coating layer is disposed on the surface of the core layer, the core layer comprises at least one of polyethylene glycol phase change materials, paraffin phase change materials, and fatty acid phase change materials, and the coating layer comprises urea-formaldehyde resin; and / or, the interface compatibility enhancer comprises at least one of hydroxyl-terminated polydimethylsiloxane, hydroxyl-terminated polyurethane prepolymer, carboxyl-terminated nitrile butadiene rubber, silane coupling agent, and silane coupling agent-modified polyethylene glycol.

[0015] This application achieves a high-performance thermal insulation layer by rationally configuring the types of micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change materials, allowing these materials to fully exert their functions. The porosity of the micro / nano aerogel particles exceeds 80%, enabling them to exert excellent thermal insulation effects and thus improving the overall thermal insulation performance of the insulation layer. Furthermore, the graphene oxide micro / nano sheets have an oxygen-containing functional group content ≥30 at%, resulting in high activity and better integration with the micro / nano ceramic particles, micro / nano aerogel particles, and microencapsulated phase change materials. The microencapsulated phase change material comprises a core layer and a coating layer; the coating layer provides space for the core layer, preventing core material leakage. By rationally setting the types of interface compatibility enhancers to have abundant highly active groups, the combination of micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets and microencapsulated phase change materials can be better realized, while also enabling the heat insulation layer to form a strong bond with the battery interior.

[0016] Optionally, the micro / nano ceramic particles are micro / nano ceramic particles modified with silane coupling agents and titanate coupling agents; and / or, the layered micro / nano sheets are layered micro / nano sheets modified with silane coupling agents; and / or, the microencapsulated phase change material is a microencapsulated phase change material modified with hydroxyl-terminated polydimethylsiloxane.

[0017] This application modifies micro / nano ceramic particles using silane coupling agents and titanate coupling agents. Silane coupling agent modification increases the bonding strength between the micro / nano ceramic particles and layered micro / nano sheets, micro / nano aerogel particles, and microencapsulated phase change materials. Titanate coupling agent modification strengthens the coordination ability of the micro / nano ceramic particles with interfacial compatibility enhancers, thereby improving interfacial bonding. By modifying layered micro / nano sheets with silane coupling agents, the interfacial bonding strength with other components is increased. By modifying the microencapsulated phase change material with hydroxyl-terminated polydimethylsiloxane, the hydroxyl-terminated polydimethylsiloxane modification not only increases its interfacial bonding strength with other components but also coordinates it with the titanate coupling agent on the surface of the micro / nano ceramic particles, further enhancing the interfacial bonding strength.

[0018] Secondly, embodiments of this application provide a method for preparing the heat insulation layer provided in the first aspect of this application, comprising: Micro-nano ceramic particles and micro-nano aerogel particles are dispersed in a first solvent to obtain a first dispersion. The layered micro / nanosheets are dispersed in a second solvent to obtain a second dispersion. The second dispersion was added to the first dispersion. After dispersion, microencapsulated phase change material and interfacial compatibility enhancer were added to the first dispersion. After dispersion, a dispersion slurry was obtained. The dispersed slurry is coated and molded, and then dried and cured to form a heat insulation layer.

[0019] This application employs a step-by-step, gradient dispersion process to uniformly disperse different components in a dispersion slurry. The uniformly dispersed slurry is then coated, molded, dried, and cured to obtain a high-performance thermal insulation layer. This application utilizes a solution dispersion, coating, and drying process, which is simple, easy to scale up for production, suitable for industrial applications, and cost-effective.

[0020] Optionally, in the step of coating the dispersed slurry into a mold, followed by drying and curing to form a heat insulation layer, the drying process includes: First, dry at 50℃~70℃ for 5h~7h to remove the solvent; Then heat to 70℃~90℃ and dry for 5h~7h to allow the interfacial compatibility enhancer, micro-nano ceramic particles, layered micro-nano sheets and microencapsulated phase change material to initially crosslink and obtain the intermediate film layer. Curing includes: The intermediate film layer is UV-cured to further crosslink the interfacial compatibility enhancer, micro / nano ceramic particles, layered micro / nano sheets, and microencapsulated phase change material.

[0021] This application sets the drying process as a gradual heating drying process. First, the free solvent is removed, so that the components in the dispersion slurry can be more uniform and fully contacted. Then, the initial cross-linking reaction between the first active group, the second active group, the third active group and the fourth active group is promoted to form a dense network. Then, ultraviolet curing is used to further promote the cross-linking between the first active group, the second active group, the third active group and the fourth active group, thereby improving the mechanical strength of the heat insulation layer.

[0022] Optionally, the microencapsulated phase change material includes a core layer and a coating layer, wherein the coating layer is disposed on the surface of the core layer and the coating layer includes urea-formaldehyde resin and silica; Methods for preparing the coating layer include: The core layer and surfactant are dispersed in deionized water to form an emulsion; The first monomer and the second monomer are mixed to obtain a mixture. The pH of the mixture is adjusted to 8-9, and after heating and reaction, a urea-formaldehyde resin prepolymer is obtained. The first monomer includes urea, and the second monomer includes formaldehyde solution. Prepolymer and nano-silica are added to an emulsion to allow the prepolymer to polymerize in situ and coat the core layer surface, thus obtaining a microencapsulated phase change material.

[0023] This application first disperses the core layer and surfactant in deionized water, so that the core layer is uniformly dispersed in the deionized water to form an emulsion; then, through the addition reaction of the first monomer and the second monomer, a urea-formaldehyde resin prepolymer with active groups is synthesized; then, the urea-formaldehyde resin prepolymer and nano-silica are added to the emulsion, and the prepolymer is cured through cross-linking, while the nano-silica is uniformly embedded in the coating layer to obtain a high-strength microencapsulated phase change material.

[0024] Thirdly, embodiments of this application provide a battery, including a heat insulation layer prepared by the method for preparing the heat insulation layer provided in the first aspect of this application or the method for preparing the heat insulation layer provided in the second aspect of this application.

[0025] This application improves the battery's thermal insulation performance, reduces the risk of thermal runaway, and enhances the battery's electrochemical performance and stability by applying a thermal insulation layer to the battery. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart illustrating the preparation process of the heat insulation layer provided in the embodiments of this application. Detailed Implementation

[0028] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of this application.

[0029] This application provides a heat insulation layer, its preparation method, and a battery. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative and do not impose numerical requirements or establish an order. Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0030] The technical solution of this application is as follows: In a first aspect, embodiments of this application provide a heat insulation layer comprising micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, microencapsulated phase change material, and an interface compatibility enhancer; wherein the surface of the micro / nano ceramic particles contains a first active group, the surface of the layered micro / nano sheets contains a second active group, the surface of the microencapsulated phase change material contains a third active group, and the interface compatibility enhancer contains a fourth active group, wherein the interface compatibility enhancer bonds at least two of the micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change material to each other.

[0031] In this application, the heat insulation layer is configured to include micro-nano ceramic particles, micro-nano aerogel particles, layered micro-nano sheets, microencapsulated phase change materials, and an interface compatibility enhancer. The surface of the micro-nano ceramic particles contains a first active group, the surface of the layered micro-nano sheets contains a second active group, the surface of the microencapsulated phase change material contains a third active group, and the interface compatibility enhancer contains a fourth active group. The first, second, third, and fourth active groups can bond with each other or undergo chemical reactions to couple with each other. This results in the uniform distribution and strong bonding of the micro-nano ceramic particles, micro-nano aerogel particles, layered micro-nano sheets, and microencapsulated phase change materials in the heat insulation layer, preventing particle agglomeration and forming a heat insulation layer with a specific microstructure. The resulting heat insulation layer has the following advantages: (1) The heat insulation layer has excellent mechanical strength, wear resistance, and crack resistance. It can adapt to mechanical stress, deformation, and vibration during battery assembly and use, and exists stably in the battery, improving the battery's service life. (2) Micro- and nano-ceramic particles have excellent thermal stability and low thermal conductivity; micro- and nano-aerogel particles have extremely low thermal conductivity (≤0.02W / (m)). The layered micro-nanosheets possess excellent high-temperature resistance and a nanoscale porous structure, which can form a multi-level porous thermal insulation framework with micro-nano ceramic particles, effectively blocking heat conduction and convection, and improving the thermal insulation performance of the insulation layer. The layered micro-nanosheets can construct a continuous sheet support network within the insulation layer, improving its mechanical properties. Simultaneously, the layered network of the micro-nanosheets supports micro-nano ceramic particles, micro-nano aerogel particles, and microencapsulated phase change materials, preventing their aggregation and further enhancing the stability of the insulation layer. Furthermore, the layered micro-nanosheets can overlap to form a "maze-like" thermal conduction barrier, extending the heat transfer path and reducing the thermal conductivity of the insulation layer. In other words, the layered micro-nanosheets can enhance mechanical strength and assist in thermal insulation. This application utilizes a specific composite structure formed by micro-nano ceramic particles, micro-nano aerogel particles, and layered micro-nanosheets to effectively hinder heat conduction, significantly reduce thermal conductivity, improve thermal insulation performance, reduce the risk of thermal runaway, and prevent the spread of thermal runaway. (3) Microencapsulated phase change materials can absorb heat and undergo phase change within a certain temperature range, enabling the insulation layer to absorb or release heat according to the temperature change of the battery, achieving temperature-responsive thermal management and intelligent temperature control, effectively suppressing the temperature rise of the battery within a certain range, and improving the safety and stability of the battery. (4) The interface compatibility enhancer can not only improve the bonding force between micro-nano ceramic particles, micro-nano aerogel particles, layered micro-nano sheets and microencapsulated phase change materials, thereby improving the mechanical properties of the insulation layer, but also improve the flexibility of the insulation layer, avoid cracking of the insulation layer, and make the insulation layer better adapt to the internal structure of the battery; in addition, the interface compatibility enhancer can also improve the interfacial adhesion between the insulation layer and the battery separator and battery shell, further ensuring the tight and stable bonding between the insulation layer and the internal structure of the battery. That is, the insulation layer of this application has excellent thermal insulation performance, mechanical properties, stability and intelligent adjustment function, and has important technical and application value, which can significantly improve the safety and service life of lithium-ion batteries.

[0032] In some embodiments, micro / nano ceramic particles account for 40% to 50% of the mass of the insulation layer.

[0033] In this application, by making micro-nano ceramic particles account for 40% to 50% of the mass of the insulation layer, the relatively high proportion of micro-nano ceramic particles can construct a continuous basic insulation skeleton for the insulation layer, while giving the insulation layer certain mechanical strength and high temperature resistance.

[0034] In some embodiments, micro / nano aerogel particles account for 5% to 10% of the mass of the insulation layer.

[0035] It is understandable that by making micro-nano aerogel particles account for 5% to 10% of the mass of the insulation layer, an appropriate amount of micro-nano aerogel particles can form a suitable amount of nanoscale pores in the insulation layer, thereby effectively suppressing heat convection and avoiding weakening the mechanical properties of the insulation layer.

[0036] In some embodiments, layered micro / nanosheets account for 8% to 12% of the mass of the insulation layer.

[0037] It is understandable that by making layered micro-nano sheets account for 8% to 12% of the mass of the insulation layer, the mechanical properties of the insulation layer can be effectively improved while forming a small amount of heat conduction channels in the insulation layer, thereby reducing its impact on the insulation performance.

[0038] In some embodiments, the microencapsulated phase change material accounts for 12% to 18% of the mass of the insulation layer.

[0039] It is understandable that by making the microencapsulated phase change material account for 12% to 18% of the mass of the insulation layer, the appropriate amount of microencapsulated phase change material can enable the insulation layer to dynamically regulate temperature changes within a certain range, while avoiding the decline in the mechanical properties of the insulation layer caused by its high proportion.

[0040] In some embodiments, the interface compatibility enhancer accounts for 2% to 5% of the mass of the insulation layer.

[0041] It is understandable that by making the interfacial compatibility enhancer account for 2% to 5% of the mass of the insulation layer, an appropriate amount can effectively improve the interfacial bonding force between micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change materials, and reduce their impact on the insulation performance of the insulation layer. That is, this application achieves a high-performance insulation layer with a specific microstructure by ensuring that the micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, microencapsulated phase change materials, and interfacial compatibility enhancer are in appropriate proportions, and through the synergistic effect of different components in appropriate amounts, a specific microstructure can be formed.

[0042] It is understandable that even when the micro-nano ceramic particles, layered micro-nano sheets, and microencapsulated phase change materials are not modified, that is, when the surface of the micro-nano ceramic particles does not contain the first active group, the surface of the layered micro-nano sheets does not contain the second active group, and the surface of the microencapsulated phase change materials does not contain the third active group, the proportion of micro-nano ceramic particles, layered micro-nano sheets, and microencapsulated phase change materials remains unchanged.

[0043] It is understandable that the insulation layer also includes coupling agents, dispersants, curing agents (such as amino resin, accounting for 3%-5%, used to promote the curing and molding of the insulation layer slurry) and defoamers / leveling agents (accounting for 0.2%~1%, used to optimize the slurry's construction performance and avoid bubbles and cracks after curing). The total mass percentage of auxiliary agents, micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, microencapsulated phase change materials, and interface compatibility enhancers is 100%.

[0044] In some embodiments, the D50 particle size of the micro / nano ceramic particles is 10 nm to 50 nm. The D50 particle size, also known as the median particle size, refers to the average particle size of the micro / nano ceramic particles, which is the particle diameter corresponding to the cumulative volume fraction reaching 50% in the cumulative particle size distribution curve of the micro / nano ceramic particle group. The D50 particle size is detected using a laser particle size analyzer (such as Malvern Mastersizer 3000), with the reference standard being GB / T 19077-2016 "Particle Size Analysis - Laser Diffraction Method". The specific testing steps are as follows: 1) Weigh 0.5g~1.0g of the particle sample to be tested, disperse it in anhydrous ethanol, add 0.1wt% of polycarboxylate dispersant, and ultrasonically disperse for 30min (power 300W, frequency 40kHz) to avoid particle agglomeration; 2) Slowly inject the dispersion into the sample cell of the laser particle size analyzer, adjust the stirring speed to 2000r / min, and ensure that the particles are uniformly suspended; 3) Start the test program, the instrument obtains the scattering spectrum of the particles through laser diffraction, and calculates the particle size distribution curve by software fitting, and reads the D50 particle size value; 4) Repeat the test 3 times and take the average value as the final result.

[0045] In this application, by making the D50 particle size of the micro-nano ceramic particles 10nm~50nm, the micro-nano ceramic particles can be uniformly filled between the interlayer gaps of the layered micro-nano sheets, effectively blocking the heat conduction channels formed between the layered micro-nano sheets and improving the heat insulation performance of the heat insulation layer.

[0046] In some embodiments, the D50 particle size of the micro / nano aerogel particles is 5 nm to 20 nm, and the method for detecting the D50 particle size is the same as that for micro / nano ceramic particles.

[0047] It is understandable that by making the D50 particle size of the micro-nano aerogel particles 5nm~20nm, the micro-nano aerogel particles can be uniformly and fully filled in the gaps between the micro-nano ceramic particles, achieving gradient dense stacking and forming a relatively dense multi-level porous thermal insulation skeleton, thereby further improving the thermal insulation performance of the thermal insulation layer.

[0048] In some embodiments, the sheet diameter of the layered micro / nanosheets is 1 μm to 3 μm. Sheet diameter refers to the average lateral dimension of the layered micro / nanosheets, which is the average diameter of the equivalent circle obtained by statistically analyzing the two-dimensional projected areas of at least 200 layered micro / nanosheets. Sheet diameter is determined using a field emission scanning electron microscope (FESEM, such as a Zeiss Sigma 300), with the reference standard GB / T 30544.10-2018 "Nanotechnology Terminology Part 10: Graphene and Related Two-Dimensional Materials". The specific testing steps are as follows: 1) Take a small amount of layered micro / nanosheets, disperse them in anhydrous ethanol, and ultrasonically disperse them for 10 min to prepare a low-concentration suspension; 2) Use a pipette to draw 10 μL of the suspension and drop it onto a clean silicon wafer surface, then let it air dry naturally; 3) Place the silicon wafer on the FESEM sample stage and perform gold sputtering treatment (current 10 mA, time 60 s) to improve conductivity; 4) Observe the sample under an accelerating voltage of 10 kV, randomly select 5 different fields of view, and count the lateral dimensions of at least 40 layered micro / nanosheets in each field of view; 5) Use ImageJ image processing software to measure the equivalent circle diameter of each layer, and calculate the average value of all statistical data, which is the D50 wafer diameter value.

[0049] It is understandable that by making the sheet diameter of the layered micro-nanosheets 1μm~3μm, the layered micro-nanosheets can form a continuous support network while avoiding their stacking, thus forming a heat insulation layer that has both mechanical strength and flexibility.

[0050] In some embodiments, the D50 particle size of the microencapsulated phase change material is 2 μm to 8 μm, and the method for detecting the D50 particle size is the same as that for micro / nano ceramic particles.

[0051] It is understandable that by making the D50 particle size of the microencapsulated phase change material 2μm~8μm, the microencapsulated phase change material with a suitable particle size can accommodate sufficient phase change material, reducing the damage to the thermal insulation layer structure caused by the phase change process of the phase change material. That is, this application achieves mutual synergy between micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets and microencapsulated phase change material of different particle sizes, so that the above components in the thermal insulation layer can be interlocked to form a relatively dense and structurally uniform thermal insulation layer.

[0052] For example, the D50 particle size of the microencapsulated phase change material is 2 μm to 8 μm, and the particle size distribution span is less than or equal to 4 μm.

[0053] In some embodiments, the insulation layer includes an insulation body layer and a hydrophobic layer disposed on at least one side surface of the insulation body layer.

[0054] In this application, by providing a hydrophobic layer on the surface of the insulation layer, the insulation layer becomes hydrophobic, which significantly reduces the wetting and adsorption capacity of water vapor, thereby enabling the insulation layer to have an anti-condensation function and better adapt to the high humidity conditions of outdoor energy storage batteries.

[0055] In some embodiments, the thickness of the insulation layer is 20μm to 50μm.

[0056] Understandably, by setting the thickness of the heat insulation layer to 20μm~50μm, its impact on battery energy density can be reduced while ensuring good heat insulation and mechanical properties. The thickness of 20μm~50μm is suitable for the ultra-thin heat insulation layer of battery separator / casing.

[0057] In some embodiments, the first active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group; and / or, the second active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group; and / or, the third active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group; and / or, the fourth active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group.

[0058] In this application, the oxygen-containing, nitrogen-containing, and sulfur-containing active groups exhibit high activity. These groups can form covalent bonds through hydrogen bonding or chemical reactions, thereby improving the interfacial bonding between micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, microencapsulated phase change materials, and interfacial compatibility enhancers, thus improving the mechanical properties of the thermal insulation layer. Simultaneously, the oxygen-containing, nitrogen-containing, and sulfur-containing active groups demonstrate good compatibility with different components and will not damage the structure and properties of different components.

[0059] In some embodiments, the micro / nano ceramic particles include at least one of micro / nano alumina particles, micro / nano zirconium oxide particles, micro / nano silicon nitride particles, and micro / nano aluminum titanate particles; and / or, the micro / nano aerogel particles have a porosity greater than 80%, and the micro / nano aerogel particles include at least one of micro / nano silica aerogel particles, micro / nano alumina aerogel particles, micro / nano silicon carbide aerogel particles, micro / nano silica-micro / nano alumina composite aerogel, and polyurethane-micro / nano silica composite aerogel; and / or, the layered micro / nano sheets include graphene oxide micro / nano sheets (GO), boron nitride micro / nano sheets, and reduced graphene oxide. The micro / nanosheets are selected from at least one of graphene micro / nanosheets, mica micro / nanosheets, and montmorillonite micro / nanosheets, wherein the oxygen-containing functional group content of the graphene oxide micro / nanosheets is ≥30 at%; and / or, the microencapsulated phase change material includes a core layer and a coating layer, wherein the coating layer is disposed on the surface of the core layer, the core layer includes at least one of polyethylene glycol phase change materials, paraffin phase change materials, and fatty acid phase change materials, and the coating layer includes urea-formaldehyde resin; and / or, the interface compatibility enhancer includes at least one of hydroxyl-terminated polydimethylsiloxane, hydroxyl-terminated polyurethane prepolymer, carboxyl-terminated nitrile butadiene rubber, silane coupling agent (e.g., KH550, KH560), and silane coupling agent-modified polyethylene glycol.

[0060] In this application, by rationally setting the types of micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change materials, the micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, and microencapsulated phase change materials can fully exert their functions, thereby obtaining a high-performance thermal insulation layer. By making the porosity of the micro / nano aerogel particles higher than 80%, the extremely high porosity enables the micro / nano aerogel particles to exert excellent thermal insulation effects, thereby improving the thermal insulation effect of the thermal insulation layer. By making the oxygen-containing functional group content of the graphene oxide micro / nano sheets ≥30at%, the oxygen-containing functional group content refers to the percentage of oxygen atoms in graphene oxide relative to the total number of carbon and oxygen atoms in graphene oxide. An appropriate number of oxygen-containing functional groups makes the graphene oxide micro / nano sheets highly active, thus enabling better integration with the micro / nano ceramic particles, micro / nano aerogel particles, and microencapsulated phase change materials. By making the microencapsulated phase change material include a core layer and a coating layer, the presence of the coating layer provides a space for the core layer, preventing core material leakage. By rationally setting the types of interface compatibility enhancers to have abundant highly active groups, the combination of micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets and microencapsulated phase change materials can be better realized, while also enabling the heat insulation layer to form a strong bond with the battery interior.

[0061] It is understandable that the porosity of micro / nano aerogel particles refers to the percentage of the volume of pores within the particles to the total volume of the particles, reflecting the porous structure characteristics of the aerogel particles. The calculation formula is as follows: Porosity (%) = (1 The porosity is calculated as (ρapparent / ρtrue) × 100%, where ρapparent refers to the apparent density of the micro / nano aerogel particles (unit: g / cm3), and ρtrue refers to the true density of the micro / nano aerogel particles. For example, when micro / nano silica aerogel particles are used, their true density is 2.2 g / cm3. Porosity was determined using a fully automated mercury porosimeter (e.g., MicroPort AutoPore IV 9500), with the reference standard being GB / T 21650.1-2008, "Determination of Pore Size Distribution and Porosity of Solid Materials by Mercury Porosimeter and Gas Adsorption Methods—Part 1: Mercury Porosimeter Method". The specific testing steps are as follows: 1) Weigh 0.2g~0.5g of dried micro / nano aerogel particle sample to constant weight and record the mass m; 2) Load the sample into the sample tube of the mercury porosimeter and evacuate to a pressure ≤0.1kPa to remove air from the sample pores; 3) Inject liquid mercury into the sample tube and gradually increase the pressure (pressure range 0.1MPa~414MPa). Under pressure, the liquid mercury gradually penetrates into the pores of the aerogel, and the instrument records the mercury ingress volume Vmercury under different pressures; 4) Calculate the apparent volume of the sample Vapparent = Vmercury + Vskeleton based on the mercury ingress volume, and calculate the apparent density ρapparent = m / Vapparent based on the sample mass; 5) Substitute into the porosity calculation formula to calculate the porosity of the micro / nano aerogel particles; 6) Repeat the test 3 times and take the average value as the final result.

[0062] For example, the D50 particle size of the microencapsulated phase change material is 2μm~8μm, the particle size distribution span is less than or equal to 4μm, the thickness of the coating layer of the microencapsulated phase change material is 0.1μm~1μm, and the porosity is less than 5%, which improves the compressive strength and heat resistance of the microencapsulated phase change material. The coating layer also includes silica, which can improve the strength of the coating layer, thereby improving the mechanical properties of the microencapsulated phase change material.

[0063] For example, the core layer includes PEG6000 and PEG10000, with a mass ratio of PEG6000 to PEG10000 of 6~8:2~4, and a phase transition temperature of 45℃~55℃, which is suitable for the critical temperature range of normal battery operation and thermal runaway.

[0064] In some embodiments, the micro / nano ceramic particles are micro / nano ceramic particles modified with silane coupling agents and titanate coupling agents.

[0065] In this application, micro-nano ceramic particles are modified by using silane coupling agents and titanate coupling agents. The silane coupling agent modification can increase the bonding force between the micro-nano ceramic particles and layered micro-nano sheets, micro-nano aerogel particles and microencapsulated phase change materials, while the titanate coupling agent modification can enhance the coordination ability of micro-nano ceramic particles with interfacial compatibility enhancers and improve interfacial bonding force.

[0066] For example, in the process of modifying micro / nano ceramic particles with silane coupling agents and titanate coupling agents, the amount of silane coupling agent is 4% to 6% of the mass of the micro / nano ceramic particles, and the amount of titanate coupling agent is 0.5% to 1% of the mass of the micro / nano ceramic particles. When the amounts of silane coupling agent and titanate coupling agent are within this range, the surface of the micro / nano ceramic particles has abundant active groups, which can better bond with the other components, thereby forming a thermal insulation layer with excellent structure.

[0067] In some embodiments, the layered micro / nanosheets are silane coupling agent modified layered micro / nanosheets, wherein the chemical grafting mass fraction of the silane coupling agent is greater than or equal to 25%, and the chemical grafting mass fraction refers to the percentage of the mass of the silane coupling agent grafted onto the surface of the layered micro / nanosheets relative to the mass of the unmodified layered micro / nanosheets.

[0068] It is understandable that by modifying layered micro / nanosheets with silane coupling agents, the silane coupling agent modification can increase their interfacial bonding force with the remaining components.

[0069] In some embodiments, the microencapsulated phase change material is a hydroxyl-terminated polydimethylsiloxane-modified microencapsulated phase change material.

[0070] It is understandable that by setting the microencapsulated phase change material as a hydroxyl-terminated polydimethylsiloxane-modified microencapsulated phase change material, the hydroxyl-terminated polydimethylsiloxane modification increases its interfacial bonding force with the other components, while coordinating it with the titanate coupling agent on the surface of the micro / nano ceramic particles, thereby further improving the interfacial bonding force.

[0071] For example, the micro / nano ceramic particles are modified micro / nano ceramic particles with 3-aminopropyltriethoxysilane (APTES) and isopropyltris(dioctylpyrophosphoryloxy) (NDZ-101). The amount of APTES is 4%~6% of the mass of the micro / nano ceramic particles, and the amount of NDZ-101 is 0.5%~1% of the mass of the micro / nano ceramic particles. The layered micro / nano sheets are APTES-modified layered micro / nano sheets, with the amount of APTES being 4%~6% of the mass of the layered micro / nano sheets. Through APTES modification, silanol groups are grafted onto the surface of the graphene oxide micro / nano sheets, achieving covalent bonding with the modified micro / nano ceramic particles. Cross-linking is employed to prevent the aggregation of layered micro / nanosheets. The encapsulated phase change material is a hydroxyl-terminated polydimethylsiloxane (PDMS-OH) modified microencapsulated phase change material, with PDMS-OH as the interfacial compatibility enhancer. The hydroxyl groups of PDMS-OH can form hydrogen bonds and covalent bonds with the amino groups of the modified micro / nano ceramic particles, the amino groups of the layered micro / nanosheets, and oxygen-containing functional groups. The NDZ-101 reinforcement of the modified micro / nano ceramic particles coordinates with the interfacial compatibility enhancer PDMS-OH and the PDMS-OH on the surface of the microcapsule shell, forming an organic-inorganic cross-linked network, which improves the bonding strength between different components. In addition, the molecular chain of PDMS-OH contains flexible segments, which can buffer thermal expansion and contraction stress and improve the toughness of the insulation layer. PDMS-OH modification increases the interfacial bonding strength between the microencapsulated phase change material and other components by at least 40%, ensuring that the microencapsulated phase change material is firmly contained in the insulation layer, preventing it from falling off and breaking, thereby avoiding leakage of the phase change material.

[0072] Secondly, please refer to Figure 1 The embodiments of this application provide a method for preparing the heat insulation layer provided in the first aspect of this application, comprising: Micro-nano ceramic particles and micro-nano aerogel particles are added to the first solvent and stirred to obtain the first dispersion. The layered micro / nano sheets were dispersed in a second solvent and sonicated to obtain a second dispersion. The second dispersion was added to the first dispersion and sonicated. Then, microencapsulated phase change material and interfacial compatibility enhancer were added to the first dispersion and stirred to obtain a dispersion slurry. The dispersed slurry is coated and molded, and then dried and cured to form a heat insulation layer.

[0073] In this application, micro / nano ceramic particles and micro / nano aerogel particles are added to a first solvent and stirred to uniformly disperse the particles, obtaining a first dispersion. Layered micro / nano sheets are then uniformly dispersed in a second solvent to obtain a second dispersion. By preparing the first and second dispersions separately and mixing them, the micro / nano ceramic particles, micro / nano aerogel particles, and layered micro / nano sheets are uniformly dispersed. Next, microencapsulated phase change materials and interfacial compatibility enhancers are added, and through a gradual addition and gradient dispersion process, the different components are uniformly dispersed in the dispersion slurry. The uniformly dispersed slurry is then coated, dried, and cured to obtain a high-performance thermal insulation layer. This application employs a solution dispersion, coating, and drying process, which is simple, easy to scale up, suitable for industrial applications, and cost-effective.

[0074] For example, the solid content of the dispersion slurry is 12% to 18%, which means that the micro-nano ceramic particles, micro-nano aerogel particles, layered micro-nano sheets and microencapsulated phase change materials account for 12% to 18% of the mass of the dispersion slurry.

[0075] For example, the dispersion slurry also includes a polycarboxylate dispersant, the amount of which is 0.1% to 0.3% of the mass of the insulation layer. The polycarboxylate dispersant is used to improve the stability and coating uniformity of the dispersion slurry.

[0076] For example, the method used to coat the dispersed slurry is a doctor blade coating process or a spray coating process, and the heat insulation layer is disposed on the lithium-ion battery separator or the inner side of the battery casing.

[0077] In some embodiments, the step of coating the dispersion slurry into a mold, followed by drying and curing to form a heat insulation layer includes drying: First, dry at 50℃~70℃ for 5h~7h to remove the solvent; Then heat to 70℃~90℃ and dry for 5h~7h to allow the interfacial compatibility enhancer, micro-nano ceramic particles, layered micro-nano sheets and microencapsulated phase change material to initially crosslink and obtain the intermediate film layer. Curing includes: The intermediate film layer is UV-cured to further crosslink the interfacial compatibility enhancer, micro / nano ceramic particles, layered micro / nano sheets, and microencapsulated phase change material.

[0078] In this application, the drying process is set as a gradual temperature increase drying, first removing free solvent, thereby making the components in the dispersion slurry more uniform and fully contacted, then promoting the initial cross-linking reaction between the first, second, third, and fourth active groups to form a dense network. Next, ultraviolet curing further promotes the cross-linking between the first, second, third, and fourth active groups, improving the mechanical strength of the insulation layer.

[0079] Understandably, in order to better improve the thermal insulation performance of the battery, a multi-layer gradient thermal insulation structure is designed for the application scenarios inside the battery casing: the inner layer (close to the casing) is a high-toughness layer (with a relatively high PDMS-OH content) to enhance the adhesion to the metal casing; the outer layer (close to the cell) is a high-thermal-insulation layer (with a relatively high content of micro-nano aerogel particles) to enhance the heat blocking effect, and the two layers are connected without interface through an intermediate transition layer (mixed ratio).

[0080] In some embodiments, the microencapsulated phase change material includes a core layer and a coating layer, wherein the coating layer is disposed on the surface of the core layer and the coating layer includes urea-formaldehyde resin and silica. Methods for preparing the coating layer include: The core layer and surfactant are dispersed in deionized water to form an emulsion; The first monomer and the second monomer are mixed to obtain a mixture. The pH of the mixture is adjusted to 8-9, and after heating and reaction, a urea-formaldehyde resin prepolymer is obtained. The first monomer includes urea, and the second monomer includes formaldehyde solution. Prepolymer and nano-silica are added to an emulsion to allow the prepolymer to polymerize in situ and coat the core layer surface, thus obtaining a microencapsulated phase change material.

[0081] In this application, the core layer and surfactant are first dispersed in deionized water. The surfactant reduces the tension at the interface between the core layer and water, allowing the core layer to be uniformly dispersed in the deionized water to form an emulsion. Then, a urea-formaldehyde resin prepolymer with active groups is synthesized through the addition reaction of the first monomer and the second monomer, providing a wall material precursor for subsequent coating. Next, the urea-formaldehyde resin prepolymer and nano-silica are added to the emulsion, and the prepolymer is cross-linked and cured, while the nano-silica is uniformly embedded in the coating layer to obtain a high-strength microencapsulated phase change material.

[0082] For example, the core layer of the microencapsulated phase change material is a PEG6000-PEG10000 composite phase change material, and the coating layer is a urea-formaldehyde resin-silica composite layer. The preparation method of the microencapsulated phase change material is as follows: 1) Emulsification and dispersion: 100 parts by mass of PEG6000-PEG10000 composite phase change material and 1.5 parts by mass of sodium dodecylbenzenesulfonate (SDBS) are added to 300 parts by mass of deionized water, and stirred in a water bath at 300 r / min and 50°C for 30 min to form a stable oil-in-water (O / W) emulsion. 2) Prepolymer preparation: 25 parts by mass of urea and 55 parts by mass of formaldehyde solution are mixed, the pH is adjusted to 8-9 with sodium hydroxide, and the mixture is reacted in a water bath at 70°C for 1 h to obtain a urea-formaldehyde resin prepolymer. 3) In-situ polymerization and coating: Urea-formaldehyde resin prepolymer and 5 parts by weight of nano-silica were added to the above emulsion. The pH was adjusted to 3-4 with citric acid, the temperature was raised to 60℃, and the mixture was stirred at 200 r / min for 4 h to form urea-formaldehyde resin-silica composite wall material. 4) Post-treatment: After the reaction was completed, the mixture was cooled to room temperature, centrifuged at 8000 r / min for 10 min, washed three times with deionized water to remove unreacted monomers, and vacuum dried at 60℃ for 12 h. Microencapsulated phase change material with a D50 of 2 μm-8 μm was obtained by sieving.

[0083] Thirdly, embodiments of this application provide a battery, including a heat insulation layer prepared by the method for preparing the heat insulation layer provided in the first aspect of this application or the method for preparing the heat insulation layer provided in the second aspect of this application.

[0084] In this application, by applying a heat insulation layer to the battery, the heat insulation performance of the battery can be improved, the risk of thermal runaway of the battery can be reduced, and the electrochemical performance and stability of the battery can be improved.

[0085] The present application will be specifically described below through specific embodiments. These embodiments are only some embodiments of the present application and are not intended to limit the present application. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0086] Example 1 This embodiment provides a heat insulation layer comprising micro / nano alumina particles, micro / nano silica aerogel particles (porosity higher than 80%), graphene oxide micro / nano sheets, microencapsulated phase change material, and PDMS-OH. The microencapsulated phase change material comprises a core layer and a coating layer, with the coating layer disposed on the surface of the core layer. The core layer is a PEG6000-PEG10000 composite phase change material (PEG6000 and PEG10000 have a mass ratio of 7:3 and a phase change temperature of 50°C). The coating layer is a urea-formaldehyde resin-silica composite shell layer with a thickness of 6 μm and a porosity ≤5%.

[0087] The surface of the micro-nano alumina particles contains a first active group. The micro-nano alumina particles are modified micro-nano alumina particles of APTES and NDZ-101, that is, the first active group is an oxygen-containing active group and a nitrogen-containing active group.

[0088] The surface of the graphene oxide micro / nanosheets contains a second active group. These graphene oxide micro / nanosheets are APTES-modified graphene oxide micro / nanosheets, meaning the second active group consists of both oxygen-containing and nitrogen-containing active groups. The oxygen-containing functional group content of the graphene oxide micro / nanosheets is 32 at%.

[0089] The surface of the microencapsulated phase change material contains a third active group. The microencapsulated phase change material is a PDMS-OH coated and modified microencapsulated phase change material, that is, the third active group is an oxygen-containing active group.

[0090] Micro-nano alumina particles account for 45% of the heat insulation layer mass, micro-nano silica aerogel particles account for 8% of the heat insulation layer mass, graphene oxide micro-nano sheets account for 10% of the heat insulation layer mass, microencapsulated phase change material accounts for 15% of the heat insulation layer mass, and PDMS-OH accounts for 3.5% of the heat insulation layer mass.

[0091] The D50 particle size of micro / nano alumina particles is 30 nm, the D50 particle size of micro / nano silica aerogel particles is 12 nm, the sheet size of graphene oxide micro / nano sheets is 2 μm, and the D50 particle size of microencapsulated phase change material is 5 μm.

[0092] The surface of the insulation layer is provided with a hydrophobic layer, and the thickness of the insulation layer is 35μm.

[0093] The method for preparing the heat insulation layer in this embodiment includes: (1) First, disperse the micro-nano alumina particles in ethanol, add APTES, sonicate for 1 h, react at room temperature for 12 h to achieve amino grafting; then add NDZ-101, react at 50℃ for 2 h, centrifuge, wash and dry to obtain bifunctional modified micro-nano alumina particles.

[0094] The amount of APTES used is 4% of the mass of the micro / nano alumina particles; the ultrasonic power is 300W and the frequency is 40kHz; the amount of NDZ-101 used is 1% of the mass of the micro / nano alumina particles.

[0095] (2) Add graphene oxide micro-nano sheets to deionized water, sonicate for 30 min, then add APTES, adjust the pH of the system to 4-5, react at 60℃ for 6 h, centrifuge, wash and dry to obtain modified graphene oxide micro-nano sheets.

[0096] The amount of APTES used was 4% of the mass of the graphene oxide micro / nanosheets. The ultrasonic power was 300W and the frequency was 40kHz.

[0097] (3) The microencapsulated phase change material was dispersed in anhydrous ethanol, pretreated with KH560, and then PDMS-OH and catalyst DBTDL were added. The crosslinking reaction was carried out at 60℃ for 4 hours. After washing and drying, PDMS-OH-coated modified microencapsulated phase change material was obtained. The water contact angle on the surface of the modified microcapsules was greater than or equal to 110°, and the latent heat retention rate of phase change was greater than or equal to 92% after 1000 cycles of cold and heat.

[0098] (4) Add APTES and NDZ-101 modified micro-nano alumina particles and nano silica aerogel particles to deionized water and mechanically stir at high speed of 1500 r / min for 30 min to obtain the first dispersion.

[0099] (5) Add APTES-modified graphene oxide micro / nanosheets to deionized water and sonicate for 30 min to obtain a second dispersion. The sonication power is 300 W and the frequency is 40 kHz.

[0100] (6) Add the second dispersion to the first dispersion and ultrasonically disperse for 30 min. Then add microencapsulated phase change material and PDMS-OH to the first dispersion, and add curing agent methyltrimethoxysilane (MTMS). Stir at low speed for 20 min at 800 r / min, and add polycarboxylate dispersant to obtain dispersion slurry.

[0101] The ultrasonic power is 300W and the frequency is 40kHz; the solid content of the dispersion slurry is 15%; the polycarboxylate dispersant is Disperbyk-190, and the amount of polycarboxylate dispersant added is 0.2% of the mass of the insulation layer.

[0102] (7) The dispersion slurry was uniformly coated onto the inner side of the lithium-ion battery casing using a doctor blade coating process. It was first dried at 60°C for 6 hours to remove free solvent; then heated to 80°C and dried for another 6 hours to promote the cross-linking reaction of the coupling agent, forming a dense network; subsequently, it was cured under low-temperature UV light to further cross-link PDMS-OH, improving the high-temperature resistance and tear resistance of the insulation layer, ultimately forming a 35μm thick insulation body layer. The low-temperature UV curing wavelength was 365nm, and the energy was 1000mJ / cm². 2 .

[0103] (8) The heat insulation body layer is surface treated with an ethanol solution of perfluorooctyltrimethoxysilane with a mass fraction of 0.5%~1% and left to stand at room temperature for 2 hours to make the static contact angle of the heat insulation layer surface ≥120°, so that it has the function of preventing condensation and is suitable for the high humidity conditions of outdoor energy storage batteries.

[0104] It is understandable that the mass of the micro / nano alumina particles, graphene oxide micro / nano sheets, and microencapsulated phase change materials can be considered unchanged before and after modification. With auxiliary functional additives (curing agent, polycarboxylate dispersant, leveling agent, and residual coupling agent) totaling 15% of the insulation layer mass, and the remainder supplemented to 100% using fumed silica, these components, after cross-linking and curing, form a dense insulation layer. The synergistic effect of these components achieves a comprehensive performance of low thermal conductivity, high mechanical strength, and anti-condensation.

[0105] Example 2 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the D50 particle size of the micro-nano alumina particles is 5nm. The rest is the same as in Embodiment 1 and will not be described again here.

[0106] Example 3 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the D50 particle size of the micro-nano alumina particles is 10nm. The rest is the same as in Embodiment 1 and will not be described again here.

[0107] Example 4 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the D50 particle size of the micro-nano alumina particles is 50nm. The rest is the same as in Embodiment 1 and will not be described again here.

[0108] Example 5 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the D50 particle size of the micro-nano alumina particles is 55nm. The rest is the same as in Embodiment 1 and will not be described again here.

[0109] Example 6 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the micro-nano alumina particles account for 38% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0110] Example 7 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the micro-nano alumina particles account for 40% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0111] Example 8 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the micro-nano alumina particles account for 50% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0112] Example 9 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the micro-nano alumina particles account for 52% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0113] Example 10 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the D50 particle size of the micro-nano silica aerogel particles is 4nm. The rest is the same as in Embodiment 1 and will not be described again here.

[0114] Example 11 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the D50 particle size of the micro-nano silica aerogel particles is 5nm. The rest is the same as in Embodiment 1 and will not be described again here.

[0115] Example 12 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the D50 particle size of the micro-nano silica aerogel particles is 20nm. The rest is the same as in Embodiment 1 and will not be described again here.

[0116] Example 13 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the D50 particle size of the micro-nano silica aerogel particles is 22nm. The rest is the same as in Embodiment 1 and will not be described again here.

[0117] Example 14 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the micro-nano silica aerogel particles account for 4% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0118] Example 15 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the micro-nano silica aerogel particles account for 5% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be repeated here.

[0119] Example 16 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the micro-nano silica aerogel particles account for 10% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0120] Example 17 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the micro-nano silica aerogel particles account for 12% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0121] Example 18 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the diameter of the graphene oxide micro / nanosheets is 0.5 μm. All other aspects are the same as in Embodiment 1 and will not be repeated here.

[0122] Example 19 This embodiment provides a heat insulation layer. The only difference from Embodiment 1 is that the diameter of the graphene oxide micro / nanosheets is 1 μm. All other aspects are the same as in Embodiment 1 and will not be repeated here.

[0123] Example 20 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the diameter of the graphene oxide micro / nanosheets is 3μm. All other aspects are the same as in Embodiment 1 and will not be repeated here.

[0124] Example 21 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the diameter of the graphene oxide micro / nanosheets is 3.5 μm. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0125] Example 22 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the oxygen-containing functional group content of the graphene oxide micro / nanosheets is 30 at%, while the rest remains the same as in Embodiment 1, and will not be repeated here.

[0126] Example 23 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the oxygen-containing functional group content of the graphene oxide micro / nanosheets is 35 at%, and the rest is consistent with Embodiment 1, which will not be repeated here.

[0127] Example 24 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the graphene oxide micro-nano sheets account for 6% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be repeated here.

[0128] Example 25 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the graphene oxide micro-nano sheets account for 8% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0129] Example 26 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the graphene oxide micro-nano sheets account for 12% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be repeated here.

[0130] Example 27 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the graphene oxide micro-nano sheets account for 15% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be repeated here.

[0131] Example 28 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that PDMS-OH accounts for 1% of the mass of the heat insulation layer. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0132] Example 29 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that PDMS-OH accounts for 2% of the mass of the heat insulation layer. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0133] Example 30 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that PDMS-OH accounts for 5% of the mass of the heat insulation layer. Everything else is the same as in Embodiment 1, and will not be repeated here.

[0134] Example 31 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that PDMS-OH accounts for 6% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0135] Example 32 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the microencapsulated phase change material accounts for 10% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be repeated here.

[0136] Example 33 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the microencapsulated phase change material accounts for 12% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be described again here.

[0137] Example 34 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the microencapsulated phase change material accounts for 18% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be repeated here.

[0138] Example 35 This embodiment provides a heat insulation layer. Compared with Embodiment 1, the only difference is that the microencapsulated phase change material accounts for 20% of the mass of the heat insulation layer. The rest is the same as in Embodiment 1, and will not be repeated here.

[0139] Example 36 This embodiment provides a heat insulation layer. Compared with embodiment 1, the only difference is that the heat insulation body layer is not subjected to the hydrophobic treatment in step (8). The rest is consistent with embodiment 1 and will not be repeated here.

[0140] Example 37 This embodiment provides a heat insulation layer. Compared with embodiment 1, the only difference is that in step (1), the amount of APTES is 6% of the mass of the micro-nano alumina particles, and the amount of NDZ-101 is 0.5% of the mass of the micro-nano alumina particles.

[0141] Example 38 This embodiment provides a heat insulation layer. Compared with embodiment 1, the only difference is that in step (1), the amount of APTES is 3% of the mass of the micro-nano alumina particles, and the amount of NDZ-101 is 1% of the mass of the micro-nano alumina particles.

[0142] Example 39 This embodiment provides a heat insulation layer. Compared with embodiment 1, the only difference is that in step (1), the amount of APTES is 7% of the mass of the micro-nano alumina particles, and the amount of NDZ-101 is 0.3% of the mass of the micro-nano alumina particles.

[0143] Comparative Example 1 This comparative example provides a heat insulation layer that differs from Example 1 only in that the heat insulation layer does not include micro / nano silica aerogel particles. Modified micro / nano alumina particles account for 56.25% of the heat insulation layer's mass, modified graphene oxide micro / nano sheets account for 12.5% ​​of the heat insulation layer's mass, PDMS-OH-coated microencapsulated phase change material accounts for 18.75% of the heat insulation layer's mass, PDMS-OH accounts for 3.75% of the heat insulation layer's mass, polycarboxylate dispersant accounts for 0.2% of the heat insulation layer's mass, curing agent accounts for 2.5% of the heat insulation layer's mass, and the remaining amount of fumed silica is made up to 100%. Other aspects are consistent with Example 1 and will not be repeated here.

[0144] The heat insulation layers prepared in Examples 1-39 and Comparative Example 1 were carefully cut along the interface between the heat insulation layer and the battery casing using a blade, so that the heat insulation layer was peeled off from the battery casing and then the performance was tested. If the heat insulation layer was too tightly bonded to the casing, the sample could be soaked in anhydrous ethanol for 2 hours to weaken the interfacial adhesion before peeling, so as to avoid cracking of the sample. The results are shown in Table 1.

[0145] Thermal conductivity refers to the thermal conductivity at room temperature (25℃), which is measured using a heat flow meter type thermal conductivity tester (such as model DRPL-III), referring to GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Insulation Materials by Heat Flow Meter Method"; high-temperature thermal conductivity (150℃) is measured using a laser flash thermal conductivity tester (such as model LFA 467 HyperFlash), referring to GB / T 10297-2015 "Determination of Thermal Conductivity of Non-metallic Solid Materials by Laser Flash Method". The specific testing process is as follows: 1) Sample preparation: Cut the insulation layer into circular samples with a diameter of 30 mm and a thickness of 35 μm, ensuring that the surface is flat and free of bubbles; 2) Room temperature test: Place the sample between the hot and cold plates of the heat flow meter tester, set the cold plate temperature to 25℃ and the hot plate temperature to 35℃, establish a stable heat flow, test for 30 minutes, record the heat flow density and temperature difference, and calculate the thermal conductivity; 3) High temperature test: Place the sample in the sample chamber of the laser flash tester, set the test temperature to 150℃, introduce nitrogen gas to protect the sample from oxidation, emit laser pulses to heat the back of the sample, record the temperature change curve of the front side over time, and calculate the thermal conductivity by software fitting.

[0146] The tensile strength and elongation at break tests are performed in accordance with GB / T 1040.3-2006 "Determination of Tensile Properties of Plastics". The specific test procedure is as follows: the insulation layer is cut into dumbbell-shaped specimens (gauge length is 25 mm and width is 4 mm). A universal testing machine (such as model Instron 5969) is used, the tensile rate is set to 5 mm / min, the maximum load and elongation at break of the specimen are recorded, and the tensile strength (σ=P / A, where P is the maximum load and A is the cross-sectional area of ​​the specimen) and elongation at break (ε=(L-L0) / L0×100%, where L is the gauge length at break and L0 is the initial gauge length) are calculated.

[0147] The number of cyclic phase transitions of phase change materials was determined using a thermal cycling-differential scanning calorimetry method. The condensation delay time was measured using the constant temperature and humidity-temperature difference control method. The residual amount of condensation was detected by weighing method.

[0148] Table 1

[0149] As can be seen from the data in Examples 1-5 in Table 1, when the particle size of the micro-nano alumina ceramic particles is between 10nm and 50nm, the thermal conductivity and condensation residue of the insulation layer are significantly lower, while the tensile strength, elongation at break, number of cyclic phase changes of the micro-nano phase change material (i.e., number of cycles of the insulation layer) and condensation delay time are significantly increased. This is mainly because the micro-nano alumina ceramic particles of 10nm to 50nm can uniformly fill the sheets of graphene oxide micro-nano sheets, forming a relatively dense and uniform insulation layer. When the particle size is too small, it is easy to agglomerate and become unevenly distributed. When the particle size is too large, it is easy to change the arrangement of graphene oxide micro-nano sheets and connect them to form heat conduction channels, destroying the insulation skeleton, thus resulting in poor performance of the insulation layer.

[0150] Data from Examples 1 and 6-9 show that the content of micro / nano alumina ceramic particles has a significant impact on the performance of the insulation layer. When the proportion of micro / nano alumina ceramic particles is 40%-50%, the insulation layer exhibits superior performance. This is likely because a suitable proportion of micro / nano ceramic particles can construct a continuous basic insulation framework for the insulation layer, and achieve a relatively dense insulation layer with uniform arrangement, strong bonding, and compactness among the micro / nano silica aerogel particles, graphene oxide micro / nano sheets, and micro / nano phase change material microcapsules, thus resulting in excellent insulation layer performance.

[0151] Data from Examples 1 and 10-13 show that when the particle size of the micro / nano silica aerogel particles is between 5 nm and 20 nm, the thermal conductivity and condensation residue of the insulation layer are relatively small, while its tensile strength, elongation at break, number of cyclic phase changes of the micro / nano phase change material, and condensation delay time are relatively large. This is mainly because the micro / nano silica aerogel particles in this particle size range can uniformly and fully fill the gaps between the micro / nano ceramic particles, achieving gradient dense stacking and forming a relatively dense multi-level porous insulation skeleton, thereby making the insulation layer perform better.

[0152] Data from Examples 1 and 14-17 show that as the content of micro / nano silica aerogel particles increases, the thermal conductivity of the insulation layer fluctuates within a certain range. Tensile strength, elongation at break, the number of cyclic phase changes of the micro / nano phase change material, and condensation delay time first increase and then decrease, while the residual condensation first decreases and then increases. This may be because an appropriate amount of micro / nano silica aerogel particles can form suitable nanoscale pores in the insulation layer, effectively suppressing heat convection. Insufficient particle size fails to form a good multi-level insulation structure, while excessive particle size results in more pores in the insulation layer, affecting its performance. When the particle size of the micro / nano silica aerogel particles is small or the content is low, the multi-level porous structure formed by the particles and micro / nano alumina ceramic particles cannot effectively suppress water vapor permeation, leading to an increase in residual condensation.

[0153] As can be seen from the data of Examples 1 and 18-21, when the diameter of the graphene oxide micro / nanosheets is between 1 μm and 3 μm, the overall performance of the thermal insulation layer is significantly better. This is mainly because the graphene oxide micro / nanosheets with a diameter of 1 μm to 3 μm can overlap to form a relatively dense and continuous support network. The graphene oxide micro / nanosheets with a smaller diameter cannot form a continuous support network, while the graphene oxide micro / nanosheets with a larger diameter are prone to stacking, thus affecting the structural rigidity and performance of the thermal insulation layer.

[0154] As can be seen from the data of Examples 1 and 22-23, the changes in the oxygen-containing functional group content of graphene oxide micro / nanosheets can affect the cross-linking structure between different components, thereby changing the microstructure of the heat insulation layer and thus affecting its performance.

[0155] As can be seen from the data of Examples 1 and Examples 24-27, the change in the content of graphene oxide micro / nanosheets has a significant impact on the performance of the thermal insulation layer. When the content of graphene oxide micro / nanosheets is too low, the resulting support network is discontinuous, which also affects the arrangement of micro / nano alumina ceramic particles and micro / nano silica aerogel particles, resulting in poor structure and performance of the thermal insulation layer. When the content of graphene oxide micro / nanosheets is too high, it not only forms abundant heat conduction channels, affecting the thermal insulation performance of the thermal insulation layer, but also affects the arrangement of micro / nano alumina ceramic particles and micro / nano silica aerogel particles, resulting in poor performance of the thermal insulation layer.

[0156] Data from Examples 1 and 28-31 show that a suitable proportion of PDMS-OH can be uniformly dispersed in the skeleton of the insulation layer, increasing the interfacial bonding force between different components and thus improving the insulation performance of the insulation layer. When the proportion of PDMS-OH is too high, the uneven distribution of different components and the disordered bonding between components weaken the strength of the insulation layer.

[0157] Data from Examples 1 and 32-35 show that when the proportion of microencapsulated phase change material is 12%-18%, the overall performance of the resulting heat insulation layer is better. When the proportion of microencapsulated phase change material is too small, it will affect the number of cycles of microencapsulated phase change material. When its content is too large, it will destroy the mutual structural strength between the other components, thus making the performance of the heat insulation layer poor.

[0158] As can be seen from the data of Example 36, when the thermal insulation body layer is not hydrophobically treated, the contact angle of the thermal insulation body layer is less than 60°, which reduces the anti-condensation performance of the thermal insulation layer (referring to the thermal insulation body layer). However, the overall performance of the thermal insulation layer is good, indicating that the anti-condensation performance of the thermal insulation layer is determined by the surface hydrophobic modification and the multi-level porous structure formed by different components.

[0159] As can be seen from the data of Examples 37-39, when the amount of APTES used in step (1) is 4%-6% and the amount of NDZ-101 is 0.5%-1%, the performance of the obtained heat insulation layer is better. However, when the amount of APTES and NDZ-101 is too high or too low, the performance of the obtained heat insulation layer is poor. This may be because when the amount of APTES and NDZ-101 is too high, the surface of the micro-nano alumina particles will be over-grafted and agglomerate. When the amount of APTES and NDZ-101 is insufficient, the different components cannot be fully cross-linked, resulting in poor performance of the heat insulation layer.

[0160] As shown in Comparative Example 1, the performance of the thermal insulation layer drops significantly when no micro / nano silica aerogel particles are added, and the number of cyclic phase changes of the phase change material is 0. This may be because the structural stability of the thermal insulation layer is extremely poor when no micro / nano silica aerogel particles are added, and it cannot buffer the volume expansion of the microencapsulated phase change material. As a result, the microencapsulated phase change material experiences capsule wall rupture and core material leakage during the first thermal cycle. This indicates that the presence of micro / nano silica aerogel particles can significantly optimize the structure of the thermal insulation layer, thereby greatly improving its performance.

[0161] The thermal conductivity of the insulation layer in this application at room temperature does not exceed 0.022 W / (m²). K), the thermal conductivity at 150℃ does not exceed 0.030 W / (m²). Compared to the insulation layer in Comparative Example 1, the thermal runaway propagation time is reduced by more than 82%, extending it to at least 60 minutes. The tensile strength is at least 6.8 MPa, the elongation at break is at least 10%, and after 50 cycles of thermal cycling from -40℃ to 85℃, there is no cracking or peeling. The interfacial bonding strength is at least 1.2 MPa, meeting the mechanical stress requirements for battery assembly and long-term service. The microencapsulated phase change material has at least 950 cyclic phase change cycles and a latent heat of phase change of at least 180 J / g. It can rapidly absorb heat and cool down when the battery temperature rises to 45℃, and slowly release heat and maintain the temperature when it drops to 25℃, keeping the battery operating temperature fluctuation range within ±3℃ without any leakage of the phase change material. After surface hydrophobic modification, under conditions of 85% humidity (RH) and a temperature difference of 10℃, the condensation delay time is at least 30 minutes, and the residual condensation is at least 8 mg / cm³. 2 It has both heat insulation and anti-condensation functions, making it suitable for the complex environment of industrial and commercial outdoor battery packs.

[0162] In summary, this application achieves a unique structure of "multi-level porous thermal insulation skeleton + tough network + temperature-controlled micro-region" through the synergistic interaction of the particle size and proportion of micro-nano ceramic particles, micro-nano aerogel particles, layered micro-nano sheets and microencapsulated phase change materials, as well as the content of microencapsulated phase change materials and interface compatibility enhancers, thereby giving the thermal insulation layer excellent performance.

[0163] The above provides a detailed description of the heat insulation layer, its preparation method, and the battery provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A heat insulation layer, characterized in that, This includes micro / nano ceramic particles, micro / nano aerogel particles, layered micro / nano sheets, microencapsulated phase change materials, and interface compatibility enhancers; The micro / nano ceramic particles contain a first active group on their surface, the layered micro / nano sheets contain a second active group on their surface, the microencapsulated phase change material contains a third active group on its surface, and the interface compatibility enhancer contains a fourth active group. The interface compatibility enhancer enables at least two of the micro / nano ceramic particles, the micro / nano aerogel particles, the layered micro / nano sheets, and the microencapsulated phase change material to bond with each other.

2. The heat insulation layer according to claim 1, characterized in that, The micro / nano ceramic particles account for 40% to 50% of the mass of the insulation layer; and / or, The micro / nano aerogel particles account for 5% to 10% of the mass of the insulation layer; and / or, The layered micro / nanosheets account for 8% to 12% of the mass of the insulation layer; and / or, The microencapsulated phase change material accounts for 12% to 18% of the mass of the insulation layer; and / or, The interface compatibility enhancer accounts for 2% to 5% of the mass of the insulation layer.

3. The heat insulation layer according to claim 1 or 2, characterized in that, The D50 particle size of the micro / nano ceramic particles is 10 nm to 50 nm; and / or, The D50 particle size of the micro / nano aerogel particles is 5nm~20nm; and / or, The sheet diameter of the layered micro / nanosheets is 1 μm to 3 μm; and / or, The D50 particle size of the microencapsulated phase change material is 2μm~8μm.

4. The heat insulation layer according to any one of claims 1 to 3, characterized in that, The thermal insulation layer includes a thermal insulation body layer and a hydrophobic layer disposed on at least one surface of the thermal insulation body layer; and / or, The thickness of the insulation layer is 20μm~50μm.

5. The heat insulation layer according to any one of claims 1 to 4, characterized in that, The first active group includes at least one of oxygen-containing active groups, nitrogen-containing active groups, and sulfur-containing active groups; and / or, The second active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group; and / or, The third active group includes at least one of an oxygen-containing active group, a nitrogen-containing active group, and a sulfur-containing active group; and / or, The fourth active group includes at least one of oxygen-containing active groups, nitrogen-containing active groups, and sulfur-containing active groups.

6. The heat insulation layer according to any one of claims 1 to 5, characterized in that, The micro / nano ceramic particles include at least one of micro / nano alumina particles, micro / nano zirconium oxide particles, micro / nano silicon nitride particles, and micro / nano aluminum titanate particles; and / or, The porosity of the micro / nano aerogel particles is higher than 80%, and the micro / nano aerogel particles include at least one of micro / nano silica aerogel particles, micro / nano alumina aerogel particles, micro / nano silicon carbide aerogel particles, micro / nano silica-micro / nano alumina composite aerogel, and polyurethane-micro / nano silica composite aerogel; and / or, The layered micro / nanosheets include at least one of graphene oxide micro / nanosheets, boron nitride micro / nanosheets, reduced graphene oxide micro / nanosheets, mica micro / nanosheets, and montmorillonite micro / nanosheets, wherein the oxygen-containing functional group content of the graphene oxide micro / nanosheets is ≥30 at%; and / or, The microencapsulated phase change material includes a core layer and a coating layer, wherein the coating layer is disposed on the surface of the core layer, and the core layer includes at least one selected from polyethylene glycol-based phase change materials, paraffin-based phase change materials, and fatty acid-based phase change materials; the coating layer includes urea-formaldehyde resin; and / or... The interface compatibility enhancer includes at least one of hydroxyl-terminated polydimethylsiloxane, hydroxyl-terminated polyurethane prepolymer, carboxyl-terminated butadiene-acrylonitrile rubber, silane coupling agent, and silane coupling agent-modified polyethylene glycol.

7. The heat insulation layer according to any one of claims 1 to 6, characterized in that, The micro / nano ceramic particles are micro / nano ceramic particles modified with silane coupling agents and titanate coupling agents; and / or, The layered micro / nanosheets are silane coupling agent modified layered micro / nanosheets; and / or, The microencapsulated phase change material is a hydroxyl-terminated polydimethylsiloxane-modified microencapsulated phase change material.

8. A method for preparing a heat insulation layer according to any one of claims 1 to 7, characterized in that, include: Micro-nano ceramic particles and micro-nano aerogel particles are dispersed in a first solvent to obtain a first dispersion. The layered micro / nanosheets are dispersed in a second solvent to obtain a second dispersion. The second dispersion is added to the first dispersion. After dispersion, microencapsulated phase change material and interfacial compatibility enhancer are added to the first dispersion. After dispersion, a dispersion slurry is obtained. The dispersed slurry is coated and molded, and then dried and cured to form a heat insulation layer.

9. The method for preparing the heat insulation layer according to claim 8, characterized in that, In the step of coating the dispersed slurry into a mold, followed by drying and curing to form a heat insulation layer, the drying process includes: First, dry at 50℃~70℃ for 5h~7h to remove the solvent; The temperature is then raised to 70℃~90℃ and dried for 5h~7h to allow the interface compatibility enhancer, the micro-nano ceramic particles, the layered micro-nano sheets and the microencapsulated phase change material to initially crosslink, thus obtaining an intermediate film layer. The curing includes: The intermediate film layer is subjected to UV curing treatment to further crosslink the interface compatibility enhancer, the micro / nano ceramic particles, the layered micro / nano sheets, and the microencapsulated phase change material.

10. The method for preparing the heat insulation layer according to claim 8 or 9, characterized in that, The microencapsulated phase change material includes a core layer and a coating layer, wherein the coating layer is disposed on the surface of the core layer and the coating layer includes urea-formaldehyde resin and silicon dioxide; The method for preparing the coating layer includes: The core layer and surfactant are dispersed in deionized water to form an emulsion; The first monomer and the second monomer are mixed to obtain a mixture. The pH of the mixture is adjusted to 8-9, and after heating and reaction, a urea-formaldehyde resin prepolymer is obtained. The first monomer includes urea, and the second monomer includes formaldehyde solution. The prepolymer and nano-silica are added to the emulsion to polymerize the prepolymer in situ and coat the core layer surface to obtain the microencapsulated phase change material.

11. A battery, characterized in that, The heat insulation layer includes the heat insulation layer as described in any one of claims 1 to 7 or the heat insulation layer prepared by the method described in claims 8 to 10.

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