Heat insulating sheet and method for preparing the same

Abstract

The invention provides a heat insulation sheet and a method for preparing the same. Specifically, the heat-insulating sheet comprises a laminate of a plurality of fiber layers laminated in this order, in which: the plurality of fiber layers each contain an inorganic fiber, a binder fiber, and inorganic filler particles, the binder fiber being melted to bond the inorganic fiber and the inorganic filler particles; the heat insulation sheet comprises a plurality of needling fixing parts penetrating through the heat insulation sheet in the direction basically perpendicular to the plane of the heat insulation sheet. According to the technical scheme, the heat insulation sheet with good compression resilience performance, heat insulation performance and mechanical performance (such as tensile strength) can be provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery thermal insulation materials, in particular, to a thermal insulation sheet and a method for preparing the same. BACKGROUND

[0002] In the construction system of batteries, thermal insulation materials play a crucial role. During the charging and discharging process of batteries, heat is generated. If the heat cannot be effectively controlled, it may lead to the degradation of battery performance. Thermal insulation materials act as a protective wall for batteries, preventing excessive heat transfer and accumulation. When the local temperature of the battery is too high, thermal insulation materials can prevent the spread of heat to other battery cells, avoiding the occurrence of thermal runaway. Once thermal runaway occurs, not only will it cause serious safety accidents such as battery fire and explosion, but also will significantly shorten the overall life of the battery pack. Therefore, providing thermal insulation materials in batteries is a key measure to ensure the safe and stable operation of batteries, prolong their service life, and improve overall performance. It is indispensable for the widespread application of batteries in various devices, especially in energy storage systems such as batteries.

[0003] In particular, with the rapid development of the electric vehicle market, the safety of lithium-ion batteries as the core energy component has become a key concern. During the use of lithium-ion batteries, thermal runaway is a serious safety threat that can cause battery fires and even explosions, posing a significant risk to personnel safety and vehicles.

[0004] In a battery module, battery cells will swell during charging, especially when fast charging (1.5C) is used. This swelling can cause deformation of the internal structure of the battery module, affecting battery performance, and even causing safety problems such as battery short circuits. Therefore, it is of great significance to set thermal insulation sheets between battery cells, which not only prevent the spread of thermal runaway within the battery module, but also need to have good compressibility, resilience, and mechanical strength to adapt to the swelling of the battery and provide structural support.

[0005] Currently, high-insulation filler thermal insulation sheets used between batteries are mostly made of inorganic fibers, adhesives, or two-component fibers and nanoparticle fillers. These components are fully mixed to form a fiber network. However, this structure has many problems. For example, adhesives, two-component fibers, or other adhesives are used to bond nanoparticles and inorganic components into a whole, but ultimately result in poor performance in compression and elasticity, and low mechanical strength of the thermal insulation sheet. In particular, the fiber network is formed by gravity, and fumed silica tends to agglomerate, resulting in uneven density distribution, making it difficult to compress during assembly, and poor resilience.

[0006] In summary, the existing thermal insulation sheet technology is difficult to meet the high performance requirements of the battery on the thermal insulation material, and the present application aims to provide a thermal insulation sheet with good compressibility, resilience, mechanical properties and thermal insulation properties, and a preparation method, so as to fill the gap in the prior art and improve the safety and performance of the battery. SUMMARY

[0007] From the above technical problems, one of the purposes of the present application is to provide a thermal insulation sheet and a method for preparing the same. The technical solution according to the present application can provide a thermal insulation sheet with good compression resilience, thermal insulation performance and mechanical properties (such as tensile strength).

[0008] Specifically, according to one aspect of the present application, a thermal insulation sheet is provided, the thermal insulation sheet comprising a laminate of a plurality of fiber layers stacked in sequence, wherein:

[0009] The plurality of fiber layers each comprises inorganic fibers, binder fibers and inorganic filler particles, the binder fibers being melted to bond the inorganic fibers and the inorganic filler particles; and

[0010] The thermal insulation sheet comprises a plurality of needle-fixed portions penetrating through the thermal insulation sheet in a direction substantially perpendicular to the plane of the thermal insulation sheet.

[0011] According to another aspect of the present application, a method for preparing a thermal insulation sheet is provided, the method comprising the following steps:

[0012] (1) mixing, opening and carding inorganic fibers with binder fibers to form a fiber layer;

[0013] (2) uniformly spraying inorganic filler particles on the upper surface of the fiber layer to obtain a fiber layer loaded with the inorganic filler particles;

[0014] (3) cross-laying a plurality of the fiber layers loaded with the inorganic filler particles to form a laminate;

[0015] (4) needle-fixing the laminate to form a needle-fixed laminate; and

[0016] (5) heat-treating the needle-fixed laminate to melt the binder fibers. BRIEF DESCRIPTION OF DRAWINGS

[0017] In the present specification, the drawings are provided to more clearly explain the technical solutions of the present application, however, the present application is not limited thereto.

[0018] Figure 1A schematic view showing a separator sheet for a battery having a double-layer structure according to one embodiment of the present application is shown. DETAILED DESCRIPTION

[0019] The present application will be further described in conjunction with the drawings and the detailed description. It will be appreciated that other embodiments are contemplated, and that these other embodiments can be practiced without departing from the scope or spirit of the application. Accordingly, the following detailed description is not intended to limit the application, as claimed.

[0020] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and other numerical values used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing an optimal blend of the features described herein. The numerical values set forth in the specific examples are reported to the precision indicated, unless indicated to be otherwise, and they will

[0021] As mentioned above, the present application focuses on the field of battery separators, aiming to provide a separator sheet with good compressibility, resilience, mechanical properties and thermal insulation performance, and a preparation method thereof, to meet the thermal management and structural stability requirements of battery monomers in battery modules, and to ensure the safe and efficient operation of battery systems.

[0022] Specifically, according to one aspect of the present application, there is provided a separator sheet comprising a laminate of a plurality of fiber layers stacked in sequence, wherein:

[0023] The plurality of fiber layers each comprises inorganic fibers, binder fibers, and inorganic filler particles, the binder fibers being fused to bond the inorganic fibers and the inorganic filler particles; and

[0024] The separator sheet comprises a plurality of needle-punched fixing portions throughout the separator sheet in a direction substantially perpendicular to the plane of the separator sheet.

[0025] Specifically, Figure 1 A schematic view showing a separator sheet 100 for a battery having a double-layer structure according to one embodiment of the present application is shown. As shown in FIG. 1, the separator sheet 100 comprises a first layer 110 and a second layer 120 stacked in sequence. Figure 1As shown in the middle, the thermal insulation sheet 100 includes a laminate of two fiber layers 1 stacked in order, wherein: each of the two fiber layers 1 includes inorganic fibers 2, binder fibers (not shown as they are melted, having no fixed shape), and inorganic filler particles 3; and the thermal insulation sheet 100 includes a plurality of needle-punched fixing portions 4 that penetrate the thermal insulation sheet 100 in a direction D substantially perpendicular to the plane of the thermal insulation sheet 100.

[0026] In the thermal insulation sheet according to the present application, the term "substantially" in the expression "the thermal insulation sheet includes a plurality of needle-punched fixing portions that penetrate the thermal insulation sheet in a direction substantially perpendicular to the plane of the thermal insulation sheet" has a specific meaning. It does not require the needle-punched fixing portions to be absolutely perpendicular to the plane of the thermal insulation sheet, but rather refers to a substantially perpendicular state. Specifically, the needle-punched fixing portions form an angle of 80 - 100° with the plane of the thermal insulation sheet, and the preferred angle range is 85 - 95°. On the one hand, at this angle, the movement and rearrangement of fibers during needle punching are more reasonable, and the fiber orientation perpendicular to the plane of the thermal insulation sheet is more stable, like a tightly arranged and stable support column, which enhances the compressive strength of the thermal insulation sheet. On the other hand, the bonding effect between adjacent fiber layers is also better, reducing the risk of interlayer separation, so that the thermal insulation sheet can function as a whole when subjected to external forces, thereby effectively improving its mechanical properties such as tensile strength.

[0027] According to certain preferred embodiments of the present application, one or more of glass fibers, ceramic fibers, alumina fibers, and basalt fibers are selected as inorganic fiber raw materials. The length thereof is in the range of 30 - 100 mm, preferably 50 - 100, more preferably 60 - 100, and most preferably 50 - 60 mm, which is beneficial for carding and makes the fibers more evenly distributed in the fiber layer, forming a stable fiber network structure. The fiber diameter is in the range of 3 - 15 μm, preferably 3 - 10 μm, and a suitable diameter helps to improve the flexibility and filling property of the fiber layer while ensuring mechanical strength. The inorganic fiber content is in the range of 20 - 77 wt%, and further preferably in the range of 30 - 70 wt%, based on the total weight of the thermal insulation sheet. When the inorganic fiber content is less than 20 wt%, the fiber network structure is loose and cannot provide sufficient support and resilience, resulting in poor resilience of the thermal insulation sheet. When the content is higher than 77 wt%, there is too much inorganic fiber, which affects the filling of the thermal insulation filler and reduces the thermal insulation performance. Specific examples of inorganic fibers that can be used in the present application include: S-glass fibers, S-glass fibers, and S-2 glass fibers available from Advanced Glass fiber Yarns LLC; R-glass fibers available from Saint-Gobain Vetrotex; and TCR635B-11-52 available from Taishan Glass Fiber Co., Ltd.

[0028] According to certain preferred embodiments of the present application, low melting point fibers are employed as binder fibers having a melting point in the range of 100-250°C, preferably 100-150°C. Suitable polymeric binder materials that can be employed as low melting point fibers include thermoplastic polymers. Preferably, the low melting point fibers are low melting point thermoplastic polymer fibers. The thermoplastic polymer is selected from the group consisting of polyolefins, polyamides, polyesters, vinyl acetate ethylene copolymers, and vinyl ester ethylene copolymers. Examples of suitable thermoplastic polymer fibers include polyolefin fibers (e.g., polyethylene or polypropylene), polystyrene fibers, polyether fibers, polyester fibers (e.g., polyethylene terephthalate (PET) or polybutylene terephthalate (PBT)), vinyl polymer fibers (e.g., polyvinyl chloride and polyvinylidene fluoride), polyamides (e.g., polycaprolactam, polyurethane, nylon fibers, and polyaramid fibers. Particularly effective binder fibers for thermal bonding can also include so-called bicomponent binder fibers, which generally comprise two different or have different physical properties of the polymer components. Typically, such fibers are core / sheath fibers, wherein for example the polymer component of the core has a higher melting point and provides mechanical strength, while the sheath has a lower melting point to enable bonding (e.g., fusion bonding). Preferably, the bicomponent binder fibers can be core / sheath polyester / polyolefin fibers.

[0029] At the specified heat treatment temperature, the low melting point fibers are able to melt and bond the inorganic fibers and inorganic filler particles to form a stable structure. The binder fibers have a diameter of 10-50 μm and a length in the range of 20-50 mm. The content of the binder fibers is 3 - 20 wt%, more preferably 8 - 10 wt%, based on 100% of the total weight of the insulation sheet. When the content is less than 3 wt%, the fiber layer structure is loose and the inorganic filler particles are easily detached, affecting the integrity and performance of the insulation sheet; when the content is more than 20 wt%, the resilience and insulation performance of the insulation sheet are reduced, because too many binder fibers occupy space, reducing the filling amount of inorganic filler particles, and affecting the elastic recovery ability of the fiber layer. Specific examples of binder fibers that can be used in the present application include ES2080 and ES4080 produced by Huvis Corporation.

[0030] According to some preferred embodiments of the present application, the inorganic filler particles can be selected from one or more of fumed silica, aerogel silica, precipitated silica and glass microspheres. The particle size is in the range of 5-50 μm, preferably 7-40 μm. A suitable particle size helps to disperse evenly in the fiber layer and improve the thermal insulation effect. The specific surface area of the inorganic filler particles is 50-500 g / m2, preferably 50-400 g / m2. This high specific surface area property makes it have good thermal insulation performance and can effectively prevent heat transfer. The content of inorganic filler particles is 20-60 wt% based on the total weight of the thermal insulation sheet. When the content is less than 20 wt%, the thermal insulation performance cannot meet the requirements and heat can easily spread in the battery module; when the content is more than 60 wt%, the inorganic filler particles are difficult to be firmly bonded in the fiber layer and are easy to fall off, which also reduces the mechanical properties of the thermal insulation sheet and makes it easy to be damaged during use. In each two adjacent fiber layers of the plurality of fiber layers, the concentration of the inorganic filler particles gradually decreases from the interface of each two adjacent fiber layers to the inside of the two adjacent fiber layers. This distribution helps to form a high thermal insulation performance layer on the surface while ensuring the stability of the internal structure of the fiber layer. In addition, according to the cross-lapping process for preparing the thermal insulation sheet of the present application, theoretically there are almost no inorganic filler particles on the exposed surfaces of the upper and lower two fiber layers on the outermost part of the thermal insulation sheet. However, the needle punching process at a later stage may carry a small amount of inorganic filler particles to the exposed surfaces of the upper and lower two fiber layers on the outermost part of the thermal insulation sheet.

[0031] According to some preferred embodiments of the present application, in the multi-layer fiber layer structure, the binder fibers inside each fiber layer melt during the heat treatment process, bonding the inorganic fibers and inorganic filler particles in this layer to form a stable fiber-filler composite structure. Optionally, at the boundary of the two adjacent fiber layers, the binder fibers in one fiber layer also melt and bond with the inorganic fibers and inorganic filler particles in the other fiber layer, thereby tightly combining the plurality of fiber layers together, enhancing the integrity and structural strength of the entire thermal insulation sheet.

[0032] According to some preferred embodiments of the present application, the thermal insulation sheet is provided with a plurality of needle fixing parts penetrating in the direction perpendicular to its plane. The density of the needle fixing parts is 300-900 pieces / cm2. The needle density has an important influence on the performance of the thermal insulation sheet. When the density is less than 300 pieces / cm2, the connection between the fiber layers is not tight enough and the mechanical properties (such as tensile strength) are too low to meet the mechanical requirements of the battery module during use, which can easily lead to the rupture or damage of the thermal insulation sheet; when the density is more than 900 pieces / cm2, the needle punching process will cause excessive damage to the fiber layer, causing excessive leakage of inorganic filler particles, thereby reducing the thermal insulation performance and failing to effectively prevent heat propagation. The needle fixing parts are uniformly distributed in the thermal insulation sheet, forming a stable reinforcing structure.

[0033] According to certain preferred embodiments of the present application, the diameter of the needles used to form the needle-fixed portion is in the range of 0.4 - 2 mm, preferably 0.5 - 1 mm. A suitable needle diameter can effectively penetrate the fiber layer without damaging the fiber and filler structure, causing the fibers to entangle with each other. During the needle punching process, the penetration and withdrawal of the needles can drive the fibers in the fiber layer to move and rearrange, forming fiber orientation perpendicular to the plane of the thermal insulation sheet. These vertically oriented fibers act as support columns, providing additional support to the thermal insulation sheet and enhancing its compression resilience performance. At the same time, the needle-fixed portion also further strengthens the connection between adjacent fiber layers, preventing interlayer separation and improving the overall mechanical strength of the thermal insulation sheet.

[0034] According to certain preferred embodiments of the present application, the thermal insulation sheet further comprises an organic encapsulation layer and / or an inorganic encapsulation layer encapsulating the layered body. The material of the organic encapsulation layer can be selected from one or more of a polyethylene terephthalate (PET) layer or a polytetrafluoroethylene (PTFE) layer. The PET film has good mechanical properties, chemical stability and insulation performance, which can provide additional protection and support for the thermal insulation sheet; the PTFE film has excellent high-temperature resistance, corrosion resistance and low friction coefficient, which can further improve the performance of the thermal insulation sheet in complex environments. The thickness of the organic encapsulation layer is in the range of 15-100 μm, a suitable thickness can effectively protect the internal fiber layer structure without excessively increasing the overall thickness and weight of the thermal insulation sheet, affecting the space utilization and energy density of the battery module.

[0035] According to certain preferred embodiments of the present application, the thermal insulation sheet can optionally be provided with an inorganic encapsulation layer. The inorganic encapsulation layer can be made of glass fiber cloth, basalt fiber cloth or ceramic fiber cloth, etc. These inorganic fiber cloths have high strength, high temperature resistance and good thermal insulation performance, which can enhance the overall mechanical strength and thermal insulation effect of the thermal insulation sheet, and prevent damage to the internal fiber layer and filler by external factors. The thickness of the inorganic encapsulation layer is in the range of 30-300 μm, and the thickness should be adjusted according to the specific application scenario and performance requirements to achieve the best protection and thermal insulation effect.

[0036] According to another aspect of the present application, a method for preparing a thermal insulation sheet is provided, the method comprising the following steps:

[0037] (1) mixing, opening and carding inorganic fibers and binder fibers to form a fiber layer;

[0038] (2) uniformly spraying inorganic filler particles on the upper surface of the fiber layer to obtain a fiber layer loaded with the inorganic filler particles;

[0039] (3) Cross-laying the plurality of the fiber layers loaded with the inorganic filler particles to form a laminate;

[0040] (4) Needle-punching the laminate to form a needle-punched laminate; and

[0041] (5) Heat-treating the needle-punched laminate to melt the binder fibers.

[0042] According to certain preferred embodiments of the present application, the selected inorganic fibers are first mixed with the binder fibers in a predetermined ratio. The mixing process ensures uniform mixing of the two types of fibers, laying the foundation for the subsequent formation of a uniform fiber layer. After mixing, an opening operation is performed, which disperses the fiber bundles into a single fiber state, increasing the bulkiness and softness of the fibers, facilitating subsequent carding and fiber layer formation.

[0043] The opened fiber mixture is carded through a carding device. The carding process further straightens and arranges the fibers into a thin layer of single filaments, and the fibers gradually form an interwoven distribution during the carding process. The face density of the carded fiber layer is controlled at 10-20 g / m². This range of face density helps to form a fiber layer with uniform thickness and stable structure, while ensuring that the fiber layer has certain strength and flexibility to support the subsequent addition of inorganic filler particles.

[0044] Subsequently, inorganic filler particles are uniformly sprayed on the upper surface of the fiber layer formed by carding. The spraying process needs to ensure that the particles are uniformly distributed on the surface of the fiber layer, avoiding local accumulation or vacancy. The amount of inorganic filler particles added is accurately controlled according to the predetermined composition ratio of the thermal insulation sheet to achieve the required thermal insulation performance.

[0045] Immediately after the completion of the particle spraying, a negative pressure is applied to the lower surface of the fiber layer. The negative pressure causes the inorganic filler particles to penetrate deeper into the interstices of the fiber layer under the driving force of the pressure difference, achieving uniform loading. The negative pressure adsorption process helps to improve the filling rate and uniformity of the inorganic filler particles in the fiber layer, thereby enhancing the thermal insulation performance of the thermal insulation sheet. At the same time, negative pressure adsorption can also reduce the risk of inorganic filler particle loss in subsequent operations, ensuring the quality stability of the thermal insulation sheet.

[0046] In the cross-laying process, the fiber layers loaded with inorganic filler particles are transported to the cross-laying machine through a clamping device. On the cross-laying machine, multiple fiber layers are cross-laid in a predetermined angle and order to form a laminate with a multi-layer structure. The cross-laying process can accurately control the laying angle and position of each fiber layer, allowing the fiber layers to interweave with each other and form a complex three-dimensional network structure, enhancing the overall strength and stability of the thermal insulation sheet.

[0047] By adjusting the number of layers and the areal density of each layer during the cross-laying process, the final thermal insulation sheet can be precisely controlled in terms of its gram weight and thickness. Depending on the application requirements, the gram weight of the thermal insulation sheet can be controlled within a certain range, such as between 300-900 g / cm2, preferably between 300-600 g / cm2, in some embodiments. The thickness is controlled between 0.5-5.0 mm, ensuring that the thermal insulation sheet can meet both the thermal insulation performance requirements and the space limitations of the battery module.

[0048] According to some preferred embodiments of the present application, the thermal insulation sheet comprises a stack of 2-30, preferably 5-10, fiber layers stacked in sequence.

[0049] According to some preferred embodiments of the present application, there is no adhesive between any two adjacent fiber layers in the plurality of fiber layers stacked in sequence.

[0050] According to some preferred embodiments of the present application, the stack formed by cross-laying is then subjected to a pre-needling process. The pre-needling uses thinner needles to initially needle the stack at a lower needle density. The purpose of pre-needling is to preliminarily fix the relative positions between the fiber layers, prevent displacement between the layers in subsequent operations, and at the same time, further compact and uniformly distribute the inorganic filler particles within the fiber layers. During the pre-needling process, the penetration of the needles causes the fibers in the fiber layers to begin to intertwine, initially forming a certain structural strength. Subsequently, the main needling process is performed based on the pre-needling. The main needling uses needles with appropriate diameter and length to needle the stack at a higher needle frequency and density. During the main needling process, the frequent penetration and withdrawal of the needles causes the fibers between the fiber layers to intertwine sufficiently, forming a more compact and stable structure. At the same time, the needling process causes the inorganic filler particles to be more firmly locked in the fiber layers, preventing them from falling off during use. After main needling, the density of the needle-fixed portion of the thermal insulation sheet reaches 300-900 / cm2, ensuring that the thermal insulation sheet has good mechanical properties and compression resilience.

[0051] In the subsequent process, the needle-processed stack is subjected to heat treatment. The heat treatment temperature is selected according to the melting point of the adhesive fibers, generally between 100-250°C, preferably 100-150°C. During the heat treatment process, the adhesive fibers melt, flow and fill into the gaps between the inorganic fibers and inorganic filler particles, and after cooling, solidify to firmly bond the inorganic fibers and inorganic filler particles together, forming a monolithic structure. The heat treatment time is adjusted according to the thickness and composition of the thermal insulation sheet, ensuring that the adhesive fibers are sufficiently melted and the bonding process is completed, while avoiding excessive heating that can damage the material properties.

[0052] Preferably, the heat-treated laminated body is subjected to a heat-conductive extrusion operation. The heat-conductive extrusion is performed under a certain pressure to further compact the thermal insulation sheet and improve its density and mechanical strength. During the extrusion process, the inorganic filler particles are more tightly packed in the fiber layers under the pressure, further optimizing the thermal insulation performance. The extruded thermal insulation sheet is immediately subjected to cooling and setting to rapidly solidify the low-melting binder fibers, maintaining the shape and structural stability of the thermal insulation sheet. A suitable cooling rate is adopted during the cooling process to avoid stress or structural defects in the material caused by too fast or too slow cooling.

[0053] Various exemplary embodiments of the present application are further illustrated by the following list of embodiments, which should not be construed as unduly limiting the application:

[0054] Specific Embodiment 1 is a thermal insulation sheet comprising a laminated body of a plurality of fiber layers stacked in sequence, wherein:

[0055] each of the plurality of fiber layers comprises inorganic fibers, binder fibers, and inorganic filler particles, the binder fibers being melted to bind the inorganic fibers and the inorganic filler particles; and

[0056] the thermal insulation sheet comprises a plurality of needle-punched fixing portions throughout the thermal insulation sheet in a direction substantially perpendicular to the plane of the thermal insulation sheet.

[0057] Specific Embodiment 2 is the thermal insulation sheet according to Specific Embodiment 1, wherein the inorganic fibers are selected from one or more of the group consisting of glass fibers, ceramic fibers, alumina fibers, and basalt fibers.

[0058] Specific Embodiment 3 is the thermal insulation sheet according to Specific Embodiment 1, wherein the length of the inorganic fibers is in the range of 30-100 mm, preferably 50-100 mm, more preferably 60-100 mm, most preferably 50-60 mm.

[0059] Specific Embodiment 4 is the thermal insulation sheet according to Specific Embodiment 1, wherein the diameter of the inorganic fibers is in the range of 3-15 μm, preferably 3-10 μm.

[0060] Specific Embodiment 5 is the thermal insulation sheet according to Specific Embodiment 1, wherein the thermal insulation sheet comprises 20-77 wt%, preferably 30-70 wt% of the inorganic fibers, based on the total weight of the thermal insulation sheet being 100%.

[0061] Specific Embodiment 6 is the thermal insulation sheet according to Specific Embodiment 1, wherein the binder fibers are low-melting thermoplastic polymer fibers.

[0062] Specific embodiment 7 is the thermal insulation sheet according to specific embodiment 1, wherein the melting point of the binder fiber is in the range of 100-250°C, preferably 100-150°C.

[0063] Specific embodiment 8 is the thermal insulation sheet according to specific embodiment 1, wherein the diameter of the binder fiber is in the range of 10-50 μm.

[0064] Specific embodiment 9 is the thermal insulation sheet according to specific embodiment 1, wherein the thermal insulation sheet comprises 3-20 wt%, preferably 8-10 wt% of the binder fiber, based on the total weight of the thermal insulation sheet as 100%.

[0065] Specific embodiment 10 is the thermal insulation sheet according to specific embodiment 1, wherein the inorganic filler particle is selected from one or more of the group consisting of fumed silica, aerogel silica, precipitated silica, and glass microspheres.

[0066] Specific embodiment 11 is the thermal insulation sheet according to specific embodiment 1, wherein the particle size of the inorganic filler particle is in the range of 5-50 μm, preferably 7-40 μm.

[0067] Specific embodiment 12 is the thermal insulation sheet according to specific embodiment 1, wherein the thermal insulation sheet comprises 20-60 wt% of the inorganic filler particle, based on the total weight of the thermal insulation sheet as 100%.

[0068] Specific embodiment 13 is the thermal insulation sheet according to specific embodiment 1, wherein:

[0069] in each of the plurality of fiber layers, the binder fiber is melted to bond the inorganic fiber and the inorganic filler particle; and / or

[0070] at the boundary of two adjacent fiber layers of the plurality of fiber layers, the binder fiber in one fiber layer is melted to bond the inorganic fiber and the inorganic filler particle in the other fiber layer.

[0071] Specific embodiment 14 is the thermal insulation sheet according to specific embodiment 1, wherein the concentration of the inorganic filler particle at the interface of each two adjacent fiber layers of the plurality of fiber layers gradually decreases from the interface to the interior of the two adjacent fiber layers.

[0072] Specific embodiment 15 is the thermal insulation sheet according to specific embodiment 1, wherein the density of the plurality of needle-punched fixing portions is 300-900 pieces / cm 2 .

[0073] Specific embodiment 16 is the thermal insulation sheet according to specific embodiment 1, wherein the diameter of the needles used to form the plurality of needle-punched fixing portions is in the range of 0.4 - 2 mm, preferably 0.5 - 1 mm.

[0074] Specific embodiment 17 is the thermal insulation sheet according to specific embodiment 1, wherein in each of the plurality of fibrous layers, the inorganic fibers are distributed in an interlaced manner with the binder fibers.

[0075] Specific embodiment 18 is the thermal insulation sheet according to specific embodiment 1, wherein the thermal insulation sheet comprises a stack of 2-30, preferably 5-10 fibrous layers stacked in sequence.

[0076] Specific embodiment 19 is the thermal insulation sheet according to specific embodiment 1, wherein there is no binder between two adjacent fibrous layers of the plurality of fibrous layers stacked in sequence.

[0077] Specific embodiment 20 is the thermal insulation sheet according to specific embodiment 1, further comprising an organic encapsulating layer and / or an inorganic encapsulating layer encapsulating the stack.

[0078] Specific embodiment 21 is the thermal insulation sheet according to specific embodiment 20, wherein the organic encapsulating layer is selected from one or more of a polyethylene terephthalate layer or a polytetrafluoroethylene layer.

[0079] Specific embodiment 22 is the thermal insulation sheet according to specific embodiment 20, wherein the thickness of the organic encapsulating layer is in the range of 15-100 μιη.

[0080] Specific embodiment 23 is the thermal insulation sheet according to specific embodiment 20, wherein the inorganic encapsulating layer is selected from one or more of a glass fiber cloth and a basalt fiber cloth.

[0081] Specific embodiment 24 is the thermal insulation sheet according to specific embodiment 20, wherein the thickness of the inorganic encapsulating layer is in the range of 30-300 μιη.

[0082] Specific embodiment 25 is the thermal insulation sheet according to specific embodiment 1, for use in an electric vehicle battery.

[0083] Specific embodiment 26 is a method of preparing the thermal insulation sheet according to any one of specific embodiments 1 to 25, the method comprising the following steps:

[0084] (1) mixing, opening and carding inorganic fibers with binder fibers to form a fibrous layer;

[0085] (2) uniformly spraying inorganic filler particles on the upper surface of the fiber layer to obtain a fiber layer loaded with the inorganic filler particles;

[0086] (3) cross-laying the plurality of the fiber layers loaded with the inorganic filler particles to form a stack;

[0087] (4) needle-punching the stack to form a needle-punched stack; and

[0088] (5) heat-treating the needle-punched stack to melt the binder fibers.

[0089] Embodiment 27 is the method of preparing a thermal insulation sheet according to Embodiment 26, wherein in step (2), after uniformly spraying inorganic filler particles on the upper surface of the fiber layer, a negative pressure is applied to the lower surface of the fiber layer.

[0090] Embodiment 28 is the method of preparing a thermal insulation sheet according to Embodiment 26, wherein the cross-laying in step (3) is performed on a cross-laying machine.

[0091] Embodiment 29 is the method of preparing a thermal insulation sheet according to Embodiment 26, wherein the needle-punching in step (4) comprises a pre-needle-punching and a main needle-punching.

[0092] Embodiment 30 is the method of preparing a thermal insulation sheet according to Embodiment 26, further comprising, after step (5):

[0093] (6) heat-conducting extruding and cooling setting the stack.

[0094] Embodiment 31 is the method of preparing a thermal insulation sheet according to Embodiment 26, wherein the inorganic fibers are selected from one or more of the group consisting of glass fibers, ceramic fibers, alumina fibers and basalt fibers.

[0095] Embodiment 32 is the method of preparing a thermal insulation sheet according to Embodiment 26, wherein the length of the inorganic fibers is in the range of 30-100 mm, preferably 50-100 mm, more preferably 60-100 mm, most preferably 50-60 mm.

[0096] Embodiment 33 is the method of preparing a thermal insulation sheet according to Embodiment 26, wherein the diameter of the inorganic fibers is in the range of 3-15 μm, preferably 3-10 μm.

[0097] Specific embodiment 34 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein the thermal insulation sheet comprises 20-77% by weight, preferably 30-70% by weight of the inorganic fibers, based on the total weight of the thermal insulation sheet.

[0098] Specific embodiment 35 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein the binder fiber is a low-melting polyester fiber.

[0099] Specific embodiment 36 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein the low-melting polyester fiber has a melting point in the range of 100-250°C, preferably 100-150°C.

[0100] Specific embodiment 37 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein the binder fiber has a diameter in the range of 10-50 μm.

[0101] Specific embodiment 38 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein the thermal insulation sheet comprises 3-20% by weight, preferably 8-10% by weight of the binder fiber, based on the total weight of the thermal insulation sheet.

[0102] Specific embodiment 39 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein the inorganic filler particles are selected from one or more of the group consisting of fumed silica, aerogel silica, precipitated silica, and glass microspheres.

[0103] Specific embodiment 40 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein the inorganic filler particles have a particle size in the range of 5-50 μm, preferably 7-40 μm.

[0104] Specific embodiment 41 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein the thermal insulation sheet comprises 20-60% by weight of the inorganic filler particles, based on the total weight of the thermal insulation sheet.

[0105] Specific embodiment 42 is the method of producing a thermal insulation sheet according to specific embodiment 26, wherein:

[0106] in each of the plurality of fiber layers, the binder fibers are melted to bind the inorganic fibers and the inorganic filler particles; and / or

[0107] at the boundary of two adjacent fiber layers of the plurality of fiber layers, the binder fibers in one fiber layer are melted to bind the inorganic fibers and the inorganic filler particles in the other fiber layer.

[0108] Specific embodiment 43 is the method of manufacturing a thermal insulation sheet according to specific embodiment 26, wherein the concentration of inorganic filler particles at the interface of each two adjacent fiber layers of the plurality of fiber layers gradually decreases from the interface towards the interior of the two adjacent fiber layers.

[0109] Specific embodiment 44 is the method of manufacturing a thermal insulation sheet according to specific embodiment 26, wherein the density of the plurality of needle-punched fixing portions is 300-900 pieces / cm 2 .

[0110] Specific embodiment 45 is the method of manufacturing a thermal insulation sheet according to specific embodiment 26, wherein the diameter of the needle used to form the plurality of needle-punched fixing portions is in the range of 0.4-2 mm, preferably 0.5-1 mm.

[0111] Specific embodiment 46 is the method of manufacturing a thermal insulation sheet according to specific embodiment 26, wherein in each fiber layer of the plurality of fiber layers, the inorganic fibers and the binder fibers are distributed in an interwoven manner.

[0112] Compared with the thermal insulation sheet for batteries in the prior art, the thermal insulation sheet according to the present application has the following advantages:

[0113] 1. Better compressibility and resilience: The thermal insulation sheet of the present application, through the multi-layer fiber structure and the needle-punching fixing process, can provide excellent compressibility and resilience. This structure enables the thermal insulation sheet to better recover after being compressed, effectively adapting to the expansion of the battery during the charging process and preventing the deformation of the internal structure of the battery module.

[0114] 2. Enhanced mechanical properties: Through the needle-punching process and the use of binder fibers, the mechanical strength of the thermal insulation sheet is significantly improved. The needle-punched fixing portions not only enhance the connection between the fiber layers, but also form fiber orientation perpendicular to the plane of the thermal insulation sheet, similar to support columns, providing additional support force, so that the thermal insulation sheet is not easy to break or damage during use.

[0115] 3. Uniform thermal insulation performance: The thermal insulation sheet of the present application achieves uniform thermal insulation effect by uniformly distributing inorganic filler particles (such as fumed silica, aerogel silica, etc.) in the fiber layers and allowing them to gradually penetrate into the interior of the fiber layers. This structural design effectively prevents the spread of heat, improving the stability and reliability of the thermal insulation performance.

[0116] 4. Flexibility and adjustability of structure: The design of the multi-layer fiber structure allows for flexible adjustment of thermal insulation performance, mechanical properties, etc. by adjusting parameters such as the number of fiber layers, thickness, content of inorganic filler particles, etc. to meet the requirements of different application scenarios.

[0117] 5. Good thermal stability: The use of low-melting polyester fibers as binder fibers with a melting point in the range of 100-250°C allows for melting and bonding of inorganic fibers and inorganic filler particles at appropriate heat treatment temperatures, forming a stable structure while ensuring thermal stability of the thermal insulation sheet in high temperature environments.

[0118] 6. Easy processing and manufacturing: The preparation method of the present application includes steps such as mixing, opening, carding, spraying inorganic filler particles, cross-laying, needle punching and heat treatment, which are relatively mature and easy to control, facilitating the realization of large-scale production and quality assurance of the thermal insulation sheet.

[0119] The present application will be described in more detail with reference to the following examples. It should be noted that these descriptions and examples are intended to facilitate understanding of the present application, and are not limiting to the present application. The scope of protection of the present application is subject to the appended claims.

[0120] Examples

[0121] In the present application, unless otherwise specified, the reagents used are commercially available products that are used directly without further purification treatment. In addition, the "%" mentioned is "weight %" and the "parts" mentioned is "weight parts".

[0122] Performance test

[0123] The thermal insulation performance, resilience performance and mechanical strength (tensile strength) of the thermal insulation sheet samples prepared in the following examples and comparative examples were tested according to the methods described below.

[0124] Thermal insulation performance test

[0125] The thermal insulation performance test is intended to evaluate the thermal insulation effect of the thermal insulation sheet in a simulated working environment of an electric vehicle battery. The test of thermal insulation performance is carried out according to the following steps.

[0126] Specifically, a sample with a size of 50 mm x 50 mm is cut from the sample sheet with a knife die, and the sample is at least 25 mm away from the edge of the sample sheet, or a finished product can be directly used. A 50 μm thick PET film is placed on the upper and lower surfaces of the sample to simulate the organic film material in actual packaging.

[0127] Then, clean the hot plate and the surface of the cold plate to make them clean and shiny. Subsequently, first, place the cold plate close to the hot plate as much as possible, and press it to 100 N at a speed of 2 mm / min, which is defined as the displacement zero point. After the displacement zero point is defined, return to the initial distance D1 between the cold plate and the hot plate, which is 320 mm.

[0128] Fix the sample covered with the upper and lower films on the cold end collection surface. Make the temperature of the hot plate rise to 600 °C, and the pressure device compress to 10 N at a speed of 800 mm / min. At this time, start collecting the temperature value T1 of the cold plate. Then compress to 0.9 MPa at a speed of 4 mm / min and keep for 300 seconds, and then release the pressure to 0.03 MPa at a speed of 4 mm / min. Keep the pressure at 0.03 MPa for 900 seconds and record the temperature value T2 of the cold surface at this time. Determine the heat insulation performance of the heat insulation sheet sample by the temperature difference (T2-T1).

[0129] For the application of the heat insulation sheet as the battery of the electric vehicle, when the grammage of the heat insulation sheet is 300 g / cm 2 , the above measured temperature difference (°C) needs to be less than or equal to 300 °C; when the grammage of the heat insulation sheet is 450 g / cm 2 , the above measured temperature difference (°C) needs to be less than or equal to 200 °C; when the grammage of the heat insulation sheet is 600 g / cm 2 , the above measured temperature difference (°C) needs to be less than or equal to 180 °C.

[0130] Rebound performance (rebound percentage) test

[0131] The test of the rebound performance (rebound percentage) is carried out according to the following steps.

[0132] Specifically, a sample with a size of 50 mm x 50 mm is cut from the sample piece using a knife die. Place the sample on the measuring table, which has a flat and smooth surface to ensure that the sample can be in good contact on its entire surface.

[0133] Slowly lower the press machine over the sample at a speed of 4 mm / min, and record the thickness value T1 when the pressure value is 4.9 KPa, which is taken as the initial value.

[0134] Continue to slowly press the sample until the pressure value is 1 MPa, and then start to slowly release the pressure plate at a speed of 4 mm / min.

[0135] When the pressure value on the pressure plate decreases to 4.9 KPa, record the thickness value at this time as T2. Calculate the rebound percentage by the following formula:

[0136] Resilience R = (T2 / T1) x 100%

[0137] For the application as a thermal insulation sheet for electric vehicle batteries, the above measured resilience percentage needs to be greater than or equal to 50% when the grammage of the thermal insulation sheet is 300 g / cm 2 ; the above measured resilience percentage needs to be greater than or equal to 40% when the grammage of the thermal insulation sheet is 450 g / cm 2 ; the above measured resilience percentage needs to be greater than or equal to 30% when the grammage of the thermal insulation sheet is 600 g / cm 2 .

[0138] Mechanical strength (tensile strength) test

[0139] The test of mechanical strength (tensile strength) is carried out according to ASTM-5035.

[0140] Specifically, a sample with a size of 50mm x 200mm is cut from a swatch using a knife die, and the sample is taken at least 25mm away from the edge of the swatch. Then, the sample is clamped by the clamps of a tensile equipment (Instron) on both sides of the 50mm width. The tensile speed is set to 304 mm / min, and the tensile equipment is started to stretch the sample until the sample is torn, and the maximum value of the tension (unit: N / mm) during the stretching process is recorded.

[0141] For the application as a thermal insulation sheet for electric vehicle batteries, the above measured tensile strength needs to be greater than or equal to 2.5 N / mm.

[0142] Example 1 (E1)

[0143] The inorganic fibers (glass fibers with a length of 51mm and a diameter of 10pm) are mixed with the binder fibers (ES2080 produced by Huvis Company, with a melting point of 115°C) to ensure uniform mixing of the two fibers. After mixing, an opening operation is carried out to disperse the fiber bundles into a single fiber state, increasing the bulkiness and softness of the fibers. The opened fiber mixture is combed by a carding device to further straighten and arrange the fibers into a single-silk thin layer of fibers, and the fibers gradually form an interlaced distribution during the carding process. The carded fiber layer has a surface density of 10-20 g / m

[0144] Then, fumed silica (with a specific surface area of 300 g / m 2 ) is uniformly sprayed on the upper surface of the carded fiber layer to ensure uniform distribution of the particles and avoid local accumulation or vacancies. After spraying, a negative pressure (-1 bar to 0.2 bar) is applied to the lower surface of the fiber layer, so that the inorganic filler particles penetrate deeper into the interstices of the fiber layer under the driving force of the pressure difference, improving the filling rate and distribution uniformity, and reducing the risk of falling off.

[0145] Subsequently, the fiber layers loaded with the inorganic filler particles are transported by the clamping device to a cross-lapper (from Zhengzhou Textile Machinery Co., Ltd.), and a plurality of fiber layers are cross-lapped to form a multilayer structure of the stack. In this process, the laying angle and position of each fiber layer are controlled to interweave the fiber layers with each other to form a complex three-dimensional network structure, enhancing the overall strength and stability of the thermal insulation sheet. By adjusting the number of fiber layer laying and the areal density of each layer, the grammage and thickness of the thermal insulation sheet can be controlled.

[0146] Then, the stack is subjected to needle punching treatment. The needle punching treatment includes pre-needle punching treatment and main needle punching treatment.

[0147] The needle-punched stack is subjected to heat treatment at 120-180°C for 5-10 minutes to melt the binder fibers. During the heat treatment, the binder fibers melt, flow and fill into the gaps between the inorganic fibers and the inorganic filler particles, and solidify after cooling to firmly bond the inorganic fibers and the inorganic filler particles together. Then, the heat-treated stack is subjected to a heat-conducting extrusion operation to further compact the thermal insulation sheet, improve the density and mechanical strength, and more tightly fill the inorganic filler particles in the fiber layers under pressure to optimize the thermal insulation performance. Immediately after extrusion, cooling and setting are performed to rapidly solidify the low-melting binder fibers, maintain the shape and structure stability of the thermal insulation sheet, thereby obtaining the thermal insulation sheet 1.

[0148] In the obtained thermal insulation sheet 1, the thermal insulation sheet 1 contains 70% by weight of glass fibers, 10% by weight of binder fibers ES2080 and 20% by weight of fumed silica, based on 100% of the total weight of the thermal insulation sheet 1. The grammage of the thermal insulation sheet 1 is 300 g / cm² and the thickness is 1.8 mm.

[0149] The corresponding properties of the thermal insulation sheet 1 are characterized according to the thermal insulation performance, resilience performance and mechanical strength (tensile strength) test methods described in detail above and the results are recorded in Table 1 below.

[0150] Examples 2-12 (E2-E17) and Comparative Examples 1-3 (CE1-CE3)

[0151] Examples 2-17 (E2-E17) and Comparative Examples 1-3 (CE1-CE3) are prepared in the same process as Example 1 to prepare thermal insulation sheets 2-17 and comparative thermal insulation sheets 1-3, with the only difference being that the contents of glass fibers, binder fibers ES2080 and fumed silica and the grammage and thickness of the obtained thermal insulation sheets are adjusted as shown in Table 1.

[0152] The respective properties of the thermal insulation sheets 2-17 and comparative thermal insulation sheets 1-3 were characterized according to the thermal insulation performance, the rebound performance and the mechanical strength (tensile strength) test methods described above in detail and the results are reported in Table 1 below.

[0153] Table 1 Composition of the thermal insulation sheets of Examples 1-17 (E1-E17) and Comparative Examples 1-3 (CE1-CE3) and results of the performance characterization

[0154]

[0155] As confirmed by the results of Examples 1-17 (E1-E17) in Table 1, the thermal insulation sheets according to the technical solution of the present application have good compression rebound performance, thermal insulation performance and tensile strength, and can be used for thermal insulation protection applications of electric vehicle batteries.

[0156] Example 7 (E7) was carried out in a similar way to Comparative Example 1 (CE1) and Comparative Example 2 (CE2), with the only difference that the thermal insulation sheets of Comparative Example 1 (CE1) and Comparative Example 2 (CE2) contained a lower amount (i.e. 10% for Comparative Example 1 and 15% for Comparative Example 2) of fumed silica. The results of Comparative Example 1 and Comparative Example 2 show that the temperature difference for characterizing the thermal insulation performance exceeds 180°C, which does not meet the basic requirements for thermal insulation protection of electric vehicle batteries.

[0157] Example 7 (E7) was carried out in a similar way to Comparative Example 3 (CE3), with the only difference that the thermal insulation sheet of Comparative Example 3 (CE3) had a lower needle density (200 needles / cm2 2 ). The results of Comparative Example 3 show that the tensile strength of the thermal insulation sheet of Comparative Example 3 (i.e. 2.1 N / mm) is lower than 2.5 N / mm, which does not meet the basic requirements regarding mechanical strength for thermal insulation protection of electric vehicle batteries.

[0158] It is clear that many modifications and changes can be made to the present disclosure without departing from the spirit and scope of the present disclosure. It is therefore intended that such modifications and changes be included within this disclosure.

Claims

1. A thermal insulation sheet comprising a laminate of a plurality of fiber layers stacked in sequence, wherein: each of the plurality of fiber layers includes inorganic fibers, binder fibers, and inorganic filler particles, the binder fibers being fused to bind the inorganic fibers and the inorganic filler particles; and the thermal insulation sheet includes a plurality of needle-punched fixing portions throughout the thermal insulation sheet in a direction substantially perpendicular to a plane of the thermal insulation sheet.

2. The thermal insulation sheet according to claim 1, wherein the inorganic fibers are selected from one or more of the group consisting of glass fibers, ceramic fibers, alumina fibers, and basalt fibers.

3. The thermal insulation sheet according to claim 1, wherein the inorganic fibers have a length in the range of 30-100 mm.

4. The thermal insulation sheet according to claim 1, wherein the inorganic fibers have a length in the range of 50-100 mm.

5. The thermal insulation sheet according to claim 1, wherein the inorganic fibers have a length in the range of 60-100 mm.

6. The thermal insulation sheet according to claim 1, wherein the inorganic fibers have a diameter in the range of 3-15 μm.

7. The thermal insulation sheet according to claim 1, wherein the thermal insulation sheet comprises 20-77% by weight of the inorganic fibers, based on a total weight of the thermal insulation sheet being 100%.

8. The thermal insulation sheet according to claim 1, wherein the binder fibers are low-melting thermoplastic polymer fibers.

9. The thermal insulation sheet according to claim 1, wherein the binder fibers have a melting point in the range of 100-250°C.

10. The thermal insulation sheet according to claim 1, wherein the binder fibers have a diameter in the range of 10-50 μm.

11. The thermal insulation sheet according to claim 1, wherein the thermal insulation sheet comprises 3-20% by weight of the binder fibers, based on a total weight of the thermal insulation sheet being 100%.

12. The thermal insulation sheet according to claim 1, wherein the inorganic filler particles are selected from one or more of the group consisting of fumed silica, aerogel silica, precipitated silica, and glass microspheres.

13. The thermal insulation sheet according to claim 1, wherein the inorganic filler particles have a particle size in the range of 5-50 μm.

14. The thermal insulation sheet according to claim 1, wherein the thermal insulation sheet comprises 20-60% by weight of the inorganic filler particles, based on a total weight of the thermal insulation sheet being 100%.

15. The thermal insulation sheet according to claim 1, wherein: in each of the plurality of fiber layers, the binder fibers are fused to bind the inorganic fibers and the inorganic filler particles; and / or at a boundary between two adjacent fiber layers of the plurality of fiber layers, binder fibers in one fiber layer are fused to bind inorganic fibers and inorganic filler particles in the other fiber layer. ​ ​ ​ ​ ​ 16. The thermal insulation sheet according to claim 1, wherein in each two adjacent fiber layers of the plurality of fiber layers, the concentration of the inorganic filler particles gradually decreases from the interface of the each two adjacent fiber layers to the interior of the two adjacent fiber layers.

17. The thermally insulating sheet of claim 1, wherein the plurality of needle-punched securements have a density of 300-900 per cm 2 .

18. The thermal insulation sheet according to claim 1, wherein the diameter of the needle used to form the plurality of needle-fixed portions is in the range of 0.4 - 2 mm.

19. The thermal insulation sheet according to claim 1, wherein in each fiber layer of the plurality of fiber layers, the inorganic fibers are distributed in an interwoven manner with the binder fibers.

20. The thermal insulation sheet according to claim 1, comprising a stack of 2-30 fiber layers stacked in sequence.

21. The thermal insulation sheet according to claim 1, comprising a stack of 5-10 fiber layers stacked in sequence.

22. The thermal insulation sheet according to claim 1, wherein there is no binder between two adjacent fiber layers of the plurality of fiber layers stacked in sequence.

23. The thermal insulation sheet according to claim 1, further comprising an organic encapsulating layer and / or an inorganic encapsulating layer encapsulating the stack.

24. The thermal insulation sheet according to claim 23, wherein the organic encapsulating layer is selected from one or more of a polyethylene terephthalate layer or a polytetrafluoroethylene layer.

25. The thermal insulation sheet according to claim 23, wherein the thickness of the organic encapsulating layer is in the range of 15-100 μm.

26. The thermal insulation sheet according to claim 23, wherein the inorganic encapsulating layer is selected from one or more of a glass fiber cloth and a basalt fiber cloth.

27. The thermal insulation sheet according to claim 23, wherein the thickness of the inorganic encapsulating layer is in the range of 30-300 μm.

28. The thermal insulation sheet according to claim 1, for use in an electric vehicle battery.

29. A method for preparing the thermal insulation sheet according to any one of claims 1 to 28, comprising the following steps: (1) mixing, opening and carding inorganic fibers with binder fibers to form a fiber layer; (2) uniformly spraying inorganic filler particles on the upper surface of the fiber layer to obtain a fiber layer loaded with the inorganic filler particles; (3) cross-laying a plurality of the fiber layers loaded with the inorganic filler particles to form a stack; (4) needle-fixing the stack to form a needle-fixed stack; and (5) heat-treating the needle-fixed stack to melt the binder fibers.

30. The method for preparing a thermal insulation sheet according to claim 29, wherein after uniformly spraying inorganic filler particles on the upper surface of the fiber layer in step (2), a negative pressure is applied to the lower surface of the fiber layer.

31. The method for preparing a thermal insulation sheet according to claim 29, wherein the cross-laying in step (3) is performed on a cross-laying machine.

32. The method of claim 29, wherein the needle-punching treatment in step (4) comprises a pre-needle-punching treatment and a main needle-punching treatment.

33. The method of claim 29, further comprising, after step (5): (6) conducting heat-conductive extrusion and cooling setting to the laminate.

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