Battery box upper cover, battery box and battery assembly

Abstract

The embodiment of the utility model discloses a battery box upper cover, a battery box and a battery assembly. The battery box upper cover comprises an outer fiber composite material skin, a metal material layer, a heat insulation layer and an inner fiber composite material skin, and the metal material layer and the heat insulation layer are arranged between the outer fiber composite material skin and the inner fiber composite material skin. And the metal material layer is used for preventing thermal erosion and impact of battery thermal runaway on the outer fiber composite material skin and preventing fire extension of battery thermal runaway. The upper cover of the battery box disclosed by the embodiment of the utility model is good in thermal runaway prevention and thermal diffusion performance, simple to manufacture and good in applicability.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and in particular to a battery box cover with anti-thermal runaway and thermal diffusion functions, a battery box with the battery box cover, and a battery assembly with the battery box. Background Technology

[0002] New energy electric vehicles are powered by batteries. Thermal runaway of these batteries can lead to fires and explosions, severely impacting safety. Battery thermal runaway primarily occurs due to internal short circuits or external forces, such as mechanical interference, electrical abuse, or thermal abuse. This causes the separator to melt, short-circuiting the positive and negative electrodes, and triggering a violent chemical reaction inside the battery. The temperature rises sharply, further intensifying the chemical reaction, creating a chain reaction and a vicious cycle that ultimately leads to a battery fire and explosion. In such cases, the high-temperature ejecta produced by the chemical reaction can easily accumulate in the pressure relief channels, causing high-voltage short circuits and potentially spreading to adjacent cells or electrical units.

[0003] Related technologies also propose attaching mica sheets to the inside of the battery box cover to prevent the spread of fire during battery thermal runaway. However, mica sheets are typically planar and cannot adapt to the complex, irregular shapes of battery box covers. A single piece of mica cannot be attached to the cover; therefore, it needs to be attached in sections, meaning multiple small pieces of mica are attached to the cover directly above the battery module. This not only complicates the process but also fails to effectively protect the vertical surface of the cover during battery thermal runaway, resulting in poor fire and heat resistance and failing to effectively slow down or prevent the spread of fire, thus lowering safety. Furthermore, the attachment of the mica sheets requires double-sided tape, making the process cumbersome and costly. After battery thermal runaway, the cover expands, causing the mica sheets to easily deform and detach. Moreover, there is a risk of mica powder falling as the vehicle moves, affecting safety. Additionally, mica sheets have poor explosion resistance. Therefore, the battery box cover in these technologies suffers from poor thermal runaway prevention and heat dissipation effects, requiring improvement. Utility Model Content

[0004] This utility model aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this utility model propose a battery box cover that exhibits good thermal runaway and heat diffusion prevention performance, is simple to manufacture, and has good applicability.

[0005] The battery box cover of this utility model embodiment includes an outer fiber composite material skin, a metal material layer, a heat insulation layer, and an inner fiber composite material skin. The metal material layer and the heat insulation layer are disposed between the outer fiber composite material skin and the inner fiber composite material skin. The metal material layer is used to prevent thermal runaway of the battery from causing thermal erosion and impact on the outer fiber composite material skin and to prevent the fire spread of the battery from thermal runaway.

[0006] In some embodiments, the metal material layer is a metal sheet and / or a metal mesh.

[0007] In some embodiments, the metal sheet is a steel sheet and / or the metal mesh is a steel wire mesh.

[0008] In some embodiments, the thickness of the metal sheet is 0.1 mm to 1 mm and / or the thickness of the metal mesh is 0.2 mm to 1 mm.

[0009] In some embodiments, the heat insulation layer is a continuous ceramic fiber layer.

[0010] In some embodiments, the thickness of the continuous ceramic fiber layer is 0.2 mm to 1 mm.

[0011] In some embodiments, the continuous ceramic fiber layer is filled with expanded graphite.

[0012] In some embodiments, the particle size of the expanded graphite ranges from 10 μm to 10000 μm.

[0013] In some embodiments, the weight ratio of expanded graphite to ceramic fiber is 1:10 to 1:5.

[0014] In some embodiments, the continuous ceramic fiber layer is made of ceramic fiber felt or ceramic fiber cloth.

[0015] In some embodiments, the continuous ceramic fiber layer includes alumina fibers, an interface layer, and an alumina ceramic matrix arranged sequentially in an inward direction from the inner fiber composite skin toward the outer fiber composite skin.

[0016] In some embodiments, the interface layer is a silicon oxide layer.

[0017] In some embodiments, the outer fiber composite skin and the inner fiber composite skin are made of continuous glass fiber and / or carbon fiber.

[0018] In some embodiments, the thickness ratio of the outer fiber composite skin, the metal material layer, the heat insulation layer, and the inner fiber composite skin is 2:1:1:2.

[0019] In some embodiments, the outer fiber composite skin, the metal material layer, the heat insulation layer, and the inner fiber composite skin are integrally formed by resin transfer molding (RTM) or resin transfer compression molding (STM).

[0020] According to an embodiment of the present utility model, the battery box includes a bottom shell and a top cover, the top cover being connected to the bottom shell, and the top cover being the battery box top cover.

[0021] According to an embodiment of the present invention, the battery assembly includes a battery box and a battery, wherein the battery is disposed inside the battery box.

[0022] The battery box cover of this utility model embodiment prevents thermal runaway and thermal diffusion damage to the battery box cover through metal material layers and heat insulation layers. The multi-layer composite material layering adapts to complex shapes. The outer fiber composite skin and inner fiber composite skin can withstand certain mechanical and thermal shocks, enhancing the structural strength of the battery box cover. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the battery box cover according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the structure of the ceramic fiber layer of the battery box cover according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the battery box according to an embodiment of the present invention.

[0026] Figure 4 This is a flowchart of the preparation method of the battery box cover according to an embodiment of the present invention.

[0027] Reference numerals: 1. Outer fiber composite skin; 2. Inner fiber composite skin; 3. Metal material layer; 4. Heat insulation layer; 41. Alumina fiber; 42. Interface layer; 43. Alumina ceramic matrix; 5. Bottom shell; 6. Top cover; 7. Battery. Detailed Implementation

[0028] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] The battery box cover of this utility model embodiment includes an outer fiber composite material skin 1, a metal material layer 3, a heat insulation layer 4, and an inner fiber composite material skin 2. The metal material layer 3 and the heat insulation layer 4 are disposed between the outer fiber composite material skin 1 and the inner fiber composite material skin 2. The metal material layer 3 is used to prevent thermal runaway of the battery from thermally eroding and impacting the outer fiber composite material skin 1, and to prevent the fire spread of the battery thermal runaway.

[0030] In other words, the metal material layer 3 and the heat insulation layer 4 are sandwiched between the outer fiber composite material skin 1 and the inner fiber composite material skin. The outer fiber composite material skin 1 and the inner fiber composite material skin 2 are made of fiber composite materials to withstand certain mechanical and thermal shocks, providing structural strength and rigidity for the battery box cover 6 and protecting the battery inside the battery box. The heat insulation layer 4 has the characteristics of high temperature resistance and low thermal conductivity, which is used to reduce and prevent the heat generated during the battery thermal runaway process from being conducted outward, and to delay the carbonization time of the outer fiber composite material skin 1 due to the excessively high internal temperature of the battery box during the thermal runaway process. This makes the outer fiber composite material skin 1 have strong mechanical properties during the thermal runaway process, thereby protecting the battery box cover 6 from being damaged by the high pressure generated by the thermal runaway. The metal material layer 3 is mainly used to resist the thermal erosion of the outer fiber composite skin 1 by the particulate matter ejected during the thermal runaway of the battery (cell). Through experiments, the inventors have found that the presence of the metal material layer 3 allows the particulate matter to accumulate above the ejection point, thereby protecting the battery box cover 6 from thermal erosion during the thermal runaway process and preventing the fire from spreading outward during the thermal runaway process inside the battery box. The battery box cover 6 formed by the multi-layer composite material can reduce the harm of battery thermal runaway, improve safety, extend the service life of the battery box, and can adapt to complex shapes.

[0031] Therefore, the battery box cover of this utility model embodiment has good performance in preventing thermal runaway and thermal diffusion, is simple to manufacture, and has good applicability.

[0032] In some embodiments, the metal material layer 3 may be a metal sheet and / or a metal mesh.

[0033] Specifically, the metal material layer 3 can be made of metal sheets, thus providing insulation and protection for the outer fiber composite skin 1. The metal sheets can reduce the heat generated during thermal runaway of the battery inside the battery box and reduce thermal erosion and impact on the outer fiber composite skin 1. Based on its planar structure and the properties of the metal material, the metal sheets have good thermal conductivity, which can prevent the battery box cover 6 from being eroded and penetrated due to excessive temperature. The metal sheets themselves have high mechanical strength, which can further improve the structural strength of the battery box cover 6 and intercept battery particles to form deposits above their spray positions, preventing the battery box cover 6 from being eroded and penetrated by heat or even fire. Preferably, the metal material layer 3 is made of metal mesh. The metal mesh has many mesh openings, which can better and more tightly bond with the outer fiber composite skin 1, improving the structural strength of the battery box cover 6. The metal mesh also has good thermal conductivity, which can prevent the battery box cover 6 from being eroded and penetrated due to excessive temperature. The hollow structure of the metal mesh reduces the weight compared to the metal sheets, making the battery box cover 6 lighter.

[0034] Optionally, a perforated structure can be arranged on the metal sheet to reduce the weight of the metal sheet while maintaining a certain structural strength. The perforated structure on the metal sheet can be holes or grooves of various shapes. The specific position of the perforated structure can be arranged to correspond to the position inside the battery box to avoid the jet points that may be formed by battery thermal runaway. The metal sheet can be tightly bonded to the outer fiber composite skin 1 and the heat insulation layer 4 through the perforated structure to ensure the overall structural strength and achieve lightweighting.

[0035] Understandably, metal mesh and metal sheets can be used in combination. The combination of metal mesh and metal sheets increases the contact area between the metal sheets and the outer fiber composite skin 1 and the heat insulation layer 4, improving the overall structural strength and reducing weight, thus contributing to the lightweighting of the battery box cover 6. When metal sheets and metal mesh are used in combination, they can better prevent particulate matter ejected during battery (cell) thermal runaway from forming deposits, thereby protecting the battery box cover 6 from thermal erosion during thermal runaway.

[0036] Optionally, the mesh size and shape of the metal mesh can be adjusted as needed. The mesh can be regular shapes such as polygons or circles. For example, hexagonal mesh can provide better mechanical properties for the metal mesh. Increasing the mesh size can reduce weight to a greater extent, while decreasing the mesh size can better block particulate matter ejected during thermal runaway of the battery (cell). The size of the mesh affects the overall mechanical properties and weight of the metal mesh, and the shape of the mesh also affects the mechanical properties of the metal mesh.

[0037] In some embodiments, the metal sheet can be a steel sheet, and the metal mesh can be a steel wire mesh.

[0038] Specifically, steel sheets are chosen for the metal sheet. The planar structure of the steel sheet provides uniform heat conduction and protection. The high structural strength and good thermal conductivity of the steel sheet form an effective barrier protecting the outer fiber composite skin 1. The steel sheet rapidly conducts heat, reducing the risk of overheating and preventing thermal erosion damage to the outer fiber composite skin 1. As the skeleton of the battery box cover 6, the steel sheet further increases mechanical strength, allowing it to withstand higher-intensity impacts and pressures. Preferably, steel wire mesh can be selected for the metal mesh. The mesh structure of the steel wire mesh allows for a tighter bond with the outer fiber composite skin 1 and the insulation layer 4, enhancing the overall structural strength. The grid distribution of the steel wire mesh effectively disperses heat and external mechanical impacts. The perforated structure of the steel wire mesh reduces the weight of the metal material layer 3, contributing to the lightweight design of the battery box cover 6. The steel sheet and steel wire mesh have low manufacturing costs.

[0039] In some embodiments, the thickness of the metal sheet can be 0.1 mm to 1 mm, and the thickness of the metal mesh can be 0.2 mm to 1 mm.

[0040] Specifically, the thickness of the metal sheet is controlled between 0.1mm and 1mm to ensure the protective effect of the metal material layer 3 on the outer fiber composite skin 1. The metal sheet has sufficient structural strength while its own weight does not affect the overall weight of the battery box cover 6. A thickness of 0.1mm provides good structural support and thermal conductivity; increasing the thickness of the metal sheet provides higher structural strength and protection. However, excessively thick metal sheets will affect the overall weight of the battery box cover 6, which is detrimental to lightweighting. A metal mesh thickness of 0.2mm to 1mm maintains sufficient strength and thermal conductivity. The metal mesh is easier to deform and process, has good shape adaptability, reduces processing difficulty, and lightens the weight of the battery box cover 6. While excessively thin metal sheets are easy to deform, they cannot provide sufficient mechanical strength to support the battery box cover 6. Excessively thin metal sheets cannot effectively intercept the thermal erosion of particles ejected during battery (cell) thermal runaway, making them easily eroded and unable to protect the outer fiber composite skin 1.

[0041] In some embodiments, the heat insulation layer 4 may be a continuous ceramic fiber layer.

[0042] Specifically, continuous ceramic fibers, as a thermal insulation material, exhibit excellent thermal stability, low thermal conductivity, and light weight. The continuous ceramic fiber layer effectively isolates high-temperature areas, preventing heat conduction to the outer fiber composite skin 1. The good chemical stability of ceramic fibers at high temperatures prevents the battery box cover 6 from participating in the chemical reactions that cause thermal runaway within the battery. Continuous ceramic fibers also possess a certain mechanical strength, which enhances impact resistance.

[0043] In some embodiments, the thickness of the continuous ceramic fiber layer can be 0.2 mm to 1 mm.

[0044] Specifically, the continuous ceramic fiber within this thickness range ensures that the insulation layer 4 is neither too thick and heavy nor too thin and thus loses its insulation effect. An excessively thick continuous ceramic fiber layer would increase the overall thickness and weight of the battery box cover 6, affecting its lightweight design. An appropriate thickness balances insulation performance and the overall weight of the material. A suitable thickness maximizes insulation while maintaining a lightweight design.

[0045] In some embodiments, the continuous ceramic fiber layer may be filled with expanded graphite.

[0046] Expanded graphite has good thermal conductivity, which is detrimental to the thermal insulation of continuous ceramic fiber layers. However, expanded graphite absorbs heat and expands upon temperature increase, increasing its thickness and thus improving the thermal insulation effect of the continuous ceramic fiber layer. Researchers have found that although filling the continuous ceramic fiber layer with expanded graphite increases its thermal conductivity, the increased thickness of the expanded graphite during thermal runaway further enhances the insulation effect. The improvement in insulation effect due to the increased thickness outweighs the negative impact of the expanded graphite's poor thermal conductivity, resulting in an overall improved thermal insulation performance for the continuous ceramic fiber layer.

[0047] Expanded graphite has a lower density than the continuous ceramic fiber layer, and adding expanded graphite can reduce the weight of the continuous ceramic fiber layer. Utilizing the thermal expansion property of expanded graphite, the thickness of the continuous ceramic fiber layer can be controlled within a suitable range for lightweighting the top cover 6. After thermal runaway occurs in the battery, the expanded graphite absorbs heat and changes the thickness of the continuous ceramic fiber layer. With increased thickness, the continuous ceramic fiber layer conducts heat for a longer period, reducing and preventing the heat generated during battery thermal runaway from being conducted outwards. This delays the carbonization time of the outer fiber composite skin 1 caused by excessively high internal temperatures during thermal runaway. Compared to a continuous ceramic fiber layer without expanded graphite, this achieves better thermal insulation.

[0048] In some embodiments, the particle size range of expanded graphite can be 10 μm to 10000 μm.

[0049] Specifically, the particle size of expanded graphite affects its distribution and filling effect in continuous ceramic fiber layers. Smaller particle size expanded graphite can fill the continuous ceramic fiber layers more uniformly, while larger particle size expanded graphite can improve the structural strength and thermal expansion coefficient of the continuous ceramic fiber layers. Research has found that a particle size range of 10 μm to 10000 μm for expanded graphite is advantageous.

[0050] When the particle size of expanded graphite is too small, the interaction force between adjacent expanded graphite particles increases, leading to agglomeration. Agglomerated expanded graphite causes localized accumulation within the continuous ceramic fiber layer, making it difficult to disperse evenly. This results in uneven overall performance of the continuous ceramic fiber layer, preventing the expanded graphite from fully realizing its thermal insulation function. Furthermore, the processing and handling of excessively small expanded graphite particles increases. Fine particles are easily lost due to airborne particles, and it is difficult to precisely control the distribution and dosage of expanded graphite particles. This also increases production costs and process complexity.

[0051] When the particle size of expanded graphite is too large, it creates significant stress concentration points within the continuous ceramic fiber layer. When this layer is subjected to external forces, these stress concentration points are prone to cracking, reducing the overall strength and toughness of the material and hindering its thermal insulation function. Furthermore, the coefficient of thermal expansion of expanded graphite differs from that of ceramic fibers. Excessively large expanded graphite particles, upon absorbing heat and expanding, can cause excessive localized stress, forming defects in the continuous ceramic fiber layer and disrupting the continuity of the insulation layer. This allows heat to be rapidly conducted through these defects, reducing overall thermal insulation performance. Cracks and defects also significantly weaken the material's structural strength. Therefore, it is necessary to control the particle size of expanded graphite to ensure the material's performance and safety.

[0052] In some embodiments, the weight ratio of expanded graphite to ceramic fiber can be 1:10 to 1:5.

[0053] Specifically, the weight ratio range of expanded graphite to ceramic fiber ensures that expanded graphite can play an effective role in thermal insulation enhancement in the continuous ceramic fiber layer, while not excessively affecting the original properties of the continuous ceramic fiber layer. This balances thermal insulation performance and mechanical strength, ensuring the thermal stability and thermal insulation effect of the continuous ceramic fiber layer.

[0054] When the proportion of expanded graphite in the gravitational ratio of expanded graphite to ceramic fiber is too small, the content of expanded graphite in the continuous ceramic fiber layer is too low to form an effective expansion network. The volume change of expanded graphite after absorbing heat and expanding is insufficient to change the thickness of the continuous ceramic fiber layer. As a result, the thermal insulation performance of the continuous ceramic fiber layer is not improved and cannot meet the requirements of practical applications. It cannot effectively delay the temperature rise of the material in high-temperature environments, and the thermal insulation performance is substandard.

[0055] When the proportion of expanded graphite in the weight ratio of expanded graphite to ceramic fiber is too high, the content of expanded graphite in the continuous ceramic fiber layer is excessive, while the content of ceramic fiber is relatively reduced. Ceramic fiber is the main load-bearing and supporting structure of the continuous ceramic fiber layer. The reduction in its content will significantly affect the original properties of the material, such as tensile strength and flexural strength, and will fail to meet the application requirements of the material in terms of strength, toughness, etc.

[0056] Excessive expanded graphite, due to its excellent thermal conductivity, reduces the overall thermal insulation performance of the continuous ceramic fiber layer. Furthermore, excessive expanded graphite particles increase the processing difficulty of the continuous ceramic fiber layer, making it harder to form and increasing scrap rates and production costs. Moreover, the thermal expansion of excessive expanded graphite particles causes significant deformation of the ceramic fibers in the continuous ceramic fiber layer, reducing the material's mechanical strength and creating stress defects within the continuous ceramic fiber layer. This disrupts the continuity of the insulation layer 4, allowing heat to be rapidly conducted through these defects, resulting in a decrease in overall thermal insulation performance.

[0057] In some embodiments, the continuous ceramic fiber layer may be made of ceramic fiber felt or ceramic fiber cloth.

[0058] Specifically, ceramic fiber felt possesses good flexibility and compressibility, enabling it to better adapt to surfaces of different shapes and provide uniform thermal insulation. Ceramic fiber felt can adapt to complex shapes, meeting the complex shape requirements of the battery box cover 6 and improving the overall thermal insulation effect. Ceramic fiber cloth has good strength and stability, making it easy to process into complex shapes and suitable for applications with complex structural shapes. Ceramic fiber cloth can also bond more tightly to the metal material layer 3, enhancing the overall structural strength.

[0059] In some embodiments, the continuous ceramic fiber layer includes alumina fibers 41, an interface layer 42, and an alumina ceramic matrix 43 arranged sequentially in the inward and outward directions from the inner fiber composite skin 2 toward the outer fiber composite skin 1.

[0060] Specifically, alumina fiber 41 provides thermal insulation and chemical stability. Interface layer 42, located between alumina fiber 41 and alumina ceramic matrix 43, acts as an intermediate layer, serving as a bond and transition, enhancing the bonding strength of the continuous ceramic fibers. The alumina ceramic matrix 43, located on the outer layer, protects the internal structure due to its high hardness and wear resistance. Alumina fiber 41, as a reinforcing phase, is the main source of the high performance of the continuous ceramic fiber layer, improving the material's strength, stiffness, and fatigue resistance. The excellent properties of alumina fiber 41 itself can significantly improve the mechanical properties of the composite material. Interface layer 42 acts as a bridge and link between alumina confinement and the alumina ceramic matrix 43, crucial for achieving effective load transfer between the carbon fibers and the matrix, and improving the overall performance of the composite material. A good interface phase enables the carbon fibers and matrix to work synergistically, fully leveraging their respective advantages to improve the interlaminar shear strength and impact resistance of the composite material.

[0061] Preferably, to obtain better interfacial performance, the alumina fiber 41 can be surface-treated to change its surface structure or introduce new active groups, such as coating treatment, to increase the active groups on the surface of the alumina fiber 41 and improve its bonding force with the alumina ceramic matrix 43. Simultaneously, selecting a suitable coupling agent can also effectively improve the performance of the interfacial phase. One end of the coupling agent molecule can bond to the surface of the alumina fiber 41, and the other end can react with the alumina ceramic matrix 43, thereby forming a stronger connection between the alumina fiber 41 and the alumina ceramic matrix 43. The coupling agent can be a silane coupling agent.

[0062] In some embodiments, the interface layer 42 may be a silicon oxide layer.

[0063] Specifically, the use of a silicon oxide layer in the interface layer 42 enhances the bonding performance between different materials, reduces the stress caused by the difference in thermal expansion coefficients between the two layers, and improves the stability and durability of the continuous ceramic fiber. The silicon oxide layer can bond well with the alumina fiber 41 and the alumina ceramic matrix 43, improving interlayer bonding. The silicon oxide layer has a similar coefficient of thermal expansion to the alumina fiber 41 and the alumina ceramic matrix 43, effectively reducing the thermal stress caused by the difference in thermal expansion coefficients between the two layers. The good thermal expansion matching of the silicon oxide layer helps alleviate stress generated during thermal cycling. The silicon oxide layer has good chemical stability and density. As an intermediate layer, the silicon oxide layer can also prevent the penetration of moisture and corrosive substances between layers, extending the service life of the fiber material.

[0064] In some embodiments, the outer fiber composite skin 1 and the inner fiber composite skin 2 may be made of continuous glass fiber and / or carbon fiber.

[0065] Specifically, glass fiber and carbon fiber are high-performance composite reinforcing fibers that provide better mechanical properties and thermal stability. Both glass fiber and carbon fiber have high strength, providing excellent structural support and enabling the outer and inner skins to protect the battery box cover 6. The low density of glass fiber and carbon fiber helps reduce overall weight, ensuring the lightweight design of the battery box cover 6. Both glass fiber and carbon fiber remain stable at high temperatures, meeting the high-temperature requirements of battery thermal runaway. Glass fiber and carbon fiber also have good corrosion resistance, allowing them to adapt to various environmental conditions.

[0066] Preferably, glass fiber and carbon fiber can be used in combination, and the weight ratio of the two can be 1:1, 2:1, etc. Using them in combination can reduce costs while maintaining a high performance level, especially in cases where the full performance of carbon fiber is not required. Glass fiber has better fracture toughness than carbon fiber, and using them in combination can improve the damage tolerance of the composite material, so that it can still maintain structural integrity when subjected to impact or damage.

[0067] In some embodiments, the thickness ratio of the outer fiber composite skin 1, the metal material layer 3, the heat insulation layer 4, and the inner fiber composite skin 2 can be 2:1:1:2.

[0068] Specifically, maintaining a thickness ratio of 2:1:1:2 for the four layers constituting the battery box cover 6 balances structural strength, thermal insulation performance, and weight, ensuring that the battery box cover 6 meets structural strength requirements while also possessing good thermal insulation performance. The outer fiber composite skin 1 is thicker than the metal layer 3, providing stronger external impact protection. The thermal insulation layer 4 has the same thickness as the metal layer 3, helping to maintain the battery's optimal operating temperature. The inner fiber composite skin 2 has the same thickness as the outer fiber composite skin 1, helping to maintain structural symmetry and stability.

[0069] Preferably, the outer fiber composite skin 1, the metal material layer, the heat insulation layer 4, and the inner fiber composite skin 2 can be integrally formed by resin transfer molding (RTM) or resin transfer compression molding (STM).

[0070] Specifically, the resin transfer molding process improves the structural integrity of the battery box cover 6 by integrally molding multiple layers of materials, allowing the resin to penetrate the multiple layers uniformly and ensuring consistent material properties. The resin transfer compression molding process differs from the resin transfer molding process; by applying pressure and heat to the mold, it accelerates resin curing and the molding of the battery box cover 6, shortening the production cycle and improving production efficiency.

[0071] This utility model embodiment also proposes a battery box, which includes a bottom shell 5 and a top cover 6. The top cover 6 is connected to the bottom shell 5, and the top cover 6 can be the battery box top cover 6 of the above embodiment. The bottom shell 5 of the battery box provides mechanical support for the battery box and provides a space for storing batteries or cells. The bottom shell 5 can protect the interior from external mechanical impacts, vibrations, etc. The bottom shell 5 and the top cover 6 form a sealed cavity, which can prevent external moisture, dust, and impurities from entering the battery box, protecting the electrical performance and chemical stability of the internal space. The top cover 6 seals the bottom shell 5 to achieve a sealing function, preventing the influence of the external environment on the battery box. The top cover 6 relies on its own mechanical structural strength and heat insulation performance to protect the battery box, reducing the influence of the external environment on the inside of the battery box and preventing the thermal runaway of the battery inside the battery box from affecting the outside of the battery box.

[0072] This utility model embodiment also proposes a battery assembly, which includes a battery box and a battery. The battery is disposed inside the battery box, which can be the battery box described in the above embodiment. The battery box protects the battery (cell) inside through its bottom shell 5 and top cover 6. The bottom shell 5 and top cover 6 resist the influence of external mechanical impact and vibration on the battery. The sealed space formed by the bottom shell 5 and top cover 6 can protect the battery from the influence of the external environment and can prevent and delay the spread of fire after thermal runaway of the battery to the outside, thereby improving safety.

[0073] This utility model embodiment also proposes a method for preparing a battery box cover, which includes the following steps:

[0074] Preforming Step: In the preforming step, the outer fiber composite skin 1, the metal material layer 3, the heat insulation layer 4, and the inner continuous fiber composite skin are sequentially placed in the preforming mold, heated to the target temperature, and maintained for a preset time to obtain the preform. In the preforming step, placing multiple layers of material sequentially in the mold and heating them allows the materials to adapt to the shape of the mold, providing a foundation for subsequent resin injection and curing. Maintaining the temperature for a certain time ensures the preforming effect and eliminates stress.

[0075] Molding Steps: In the molding step, the preform is transferred to the molding mold, resin is injected into the molding mold, a preset clamping force is applied to the molding mold, and this is maintained for a predetermined time. Applying pressure to the mold during the molding step accelerates resin curing and improves production efficiency.

[0076] Depressurize the molding die to obtain the molded product.

[0077] In some embodiments, the molding steps include a first stage, a second stage, and a third stage, wherein the resin injection pressure, duration, and clamping force of the second stage are greater than those of the first stage, and less than those of the third stage.

[0078] Specifically, in the first stage, the resin injection pressure, duration, and clamping force are relatively low. The purpose of the first stage is to initially inject the resin so that it can begin to penetrate the fiber layer and the metal material layer 3. At the same time, it avoids material damage or displacement due to excessive pressure, and ensures that there are no residual air bubbles between the material layers and that the resin is evenly distributed.

[0079] In the second stage, the resin injection pressure, duration, and clamping force are all higher than in the first stage. The purpose of the second stage is to further promote the resin to penetrate deeper into the material layers, enhance the interlayer adhesion, improve the resin penetration depth and uniformity, and ensure the mechanical properties of the composite component.

[0080] The third stage is the stage of highest pressure and clamping force, where the resin injection pressure, duration, and clamping force reach their maximum values. The purpose of this stage is to ensure that the resin completely penetrates all material layers and promotes rapid curing of the resin under high pressure.

[0081] To achieve optimal resin penetration and curing, and to ensure the dimensional accuracy and performance of the final product, staged molding allows for better control of the resin penetration process, avoiding insufficient penetration or damage caused by uneven pressure. By gradually increasing pressure and clamping force, optimal adhesion between the resin and the fiber layer, metal layer, and insulation layer 4 can be ensured, improving the mechanical properties and thermal stability of the final product. Staged molding helps reduce internal bubbles and defects, improving the overall quality of the product. By precisely controlling the parameters of each stage, the production process can be optimized, increasing production efficiency and output.

[0082] In some embodiments, the target temperature in the preforming step can be 90-120 degrees Celsius, and the preset time can be 1-5 minutes;

[0083] In the molding process, the resin injection pressure in the first stage can be 5-7 MPa, the duration can be 8-12 seconds, and the clamping force can be 800-1200 tons. The resin injection pressure in the second stage can be 7-9 MPa, the duration can be 3-7 seconds, and the clamping force can be 1800-2200 tons. The resin injection pressure in the third stage can be 11-13 MPa, the duration can be 2-4 seconds, and the clamping force can be 2800-3200 tons.

[0084] The first stage involves injecting resin into the mold under low pressure to avoid damaging the pre-formed material structure. Too low a pressure may result in insufficient resin flow and incomplete filling; too high a pressure may damage the material or cause damage to the mold.

[0085] Maintaining a certain duration ensures that the resin has enough time to flow and fill all parts of the mold. If the duration is too short, the resin may not be able to completely fill the mold; if the duration is too long, the resin may cure prematurely, affecting the molding result.

[0086] Maintaining the clamping force within the target range keeps the mold closed, preventing it from opening during resin injection. Insufficient clamping force may cause the mold to open, resulting in molding failure; excessive clamping force may damage the mold. Appropriate clamping force ensures the mold remains closed under high pressure.

[0087] Increasing the clamping force helps resist the mold opening force generated by the increased injection pressure, ensuring the mold remains closed under high pressure. Using higher injection pressure in the third stage ensures complete resin filling of the mold, and the high pressure also improves the product's density and mechanical properties. As the injection pressure increases, the clamping force also increases.

[0088] The resin can be either epoxy resin or polyurethane resin. Both epoxy and polyurethane resins have good mechanical properties, chemical resistance, and heat resistance. Epoxy resin cures quickly and has high strength, while polyurethane resin has better flexibility and impact resistance. The appropriate resin can be selected according to the specific requirements of the product.

[0089] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0090] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0091] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0092] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0093] In this utility model, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this utility model. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0094] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A battery box cover, characterized in that, include: The outer fiber composite skin (1), the metal material layer (3), the heat insulation layer (4) and the inner fiber composite skin (2) are provided between the outer fiber composite skin (1) and the inner fiber composite skin (2). The metal material layer (3) is used to prevent the thermal runaway of the battery from causing thermal erosion and impact on the outer fiber composite skin (1) and to prevent the fire extension of the battery thermal runaway.

2. The battery box cover according to claim 1, characterized in that, The metal material layer (3) is a metal sheet and / or a metal mesh.

3. The battery box cover according to claim 2, characterized in that, The metal sheet is a steel sheet and / or the metal mesh is a steel wire mesh.

4. The battery box cover according to claim 2, characterized in that, The thickness of the metal sheet is 0.1 mm to 1 mm and / or the thickness of the metal mesh is 0.2 mm to 1 mm.

5. The battery box cover according to any one of claims 1-4, characterized in that, The heat insulation layer (4) is a continuous ceramic fiber layer.

6. The battery box cover according to claim 5, characterized in that, The thickness of the continuous ceramic fiber layer is 0.2 mm to 1 mm.

7. The battery box cover according to claim 5, characterized in that, The continuous ceramic fiber layer is filled with expanded graphite.

8. The battery box cover according to claim 7, characterized in that, The expanded graphite has a particle size range of 10 μm to 10000 μm.

9. The battery box cover according to claim 7, characterized in that, The weight ratio of expanded graphite to ceramic fiber is 1:10 to 1:

5.

10. The battery box cover according to claim 5, characterized in that, The continuous ceramic fiber layer is made of ceramic fiber felt or ceramic fiber cloth.

11. The battery box cover according to claim 5, characterized in that, The continuous ceramic fiber layer includes alumina fibers (41), an interface layer (42), and an alumina ceramic matrix (43) arranged sequentially in the inward and outward directions from the inner fiber composite skin (2) toward the outer fiber composite skin (1).

12. The battery box cover according to claim 11, characterized in that, The interface layer (42) is a silicon oxide layer.

13. The battery box cover according to claim 1, characterized in that, The outer fiber composite skin (1) and the inner fiber composite skin (2) are made of continuous glass fiber and / or carbon fiber.

14. The battery box cover according to claim 1, characterized in that, The thickness ratio of the outer fiber composite skin (1), the metal material layer (3), the heat insulation layer (4), and the inner fiber composite skin (2) is 2:1:1:

2.

15. The battery box cover according to claim 1, characterized in that, The outer fiber composite skin (1), the metal material layer, the heat insulation layer (4), and the inner fiber composite skin (2) are integrally formed by resin transfer molding (RTM) or resin transfer compression molding (STM).

16. A battery box, characterized in that, It includes a bottom shell (5) and a top cover (6), the top cover (6) being connected to the bottom shell (5), and the top cover (6) being the battery box top cover (6) according to any one of claims 1-15.

17. A battery assembly, characterized in that, It includes a battery box and a battery, the battery being disposed inside the battery box, the battery box being the battery box according to claim 16.

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