Bionic integrated battery pack cover plate and preparation method thereof

Abstract

The invention relates to the technical field of power battery structures, in particular to a bionic integrated battery pack cover plate and a preparation method thereof. The bionic integrated battery pack cover plate comprises a plurality of anti-shearing structure layers and a plurality of anti-impact structure layers which are arranged in a stacked manner, the plurality of anti-shearing structure layers form an anti-shearing inner layer, and the plurality of anti-impact structure layers form an anti-impact outer layer; each anti-shearing structure layer is provided with a first fiber structure, and each anti-impact structure layer is provided with a second fiber structure; and the anti-shearing structure layer and the anti-impact structure layer are spirally arranged. The invention provides a structural design of a bionic integrated battery cover plate based on a mantis shrimp chelant rod structure, namely an anti-shearing inner layer and an anti-impact outer layer which are used as a core stress layer of a cover plate material during thermal runaway, and the anti-shearing and anti-impact integrated battery cover plate can be obtained through a synergistic effect of'hard outside and tough inside 'and an energy dissipation mechanism of a'spiral laying layer'. The impact resistance and the fracture toughness which are far better than those of a traditional design are shown, and an internal battery cell is effectively protected.

Description

Technical Field

[0001] This application relates to the field of power battery structure technology, and in particular to a biomimetic integrated battery pack cover plate and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the safety issues of power batteries have become increasingly prominent. Among them, thermal runaway, due to its suddenness and destructiveness, has become the root cause of accidents such as battery fires and explosions.

[0003] Existing battery pack cover technologies generally suffer from the problem of functional stacking, i.e., achieving multiple layers of protection by independently stacking modules such as explosion-proof valves, heat insulation layers, and impact-resistant layers. This results in bulky structures, high costs, complex assembly, and interfaces prone to failure. Furthermore, material selection is limited, making it difficult to achieve both high strength and lightweight performance in a single component. These problems severely restrict the safety, lightweight design, and reliability of battery packs. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a biomimetic integrated battery pack cover and its manufacturing method, so as to solve the above-mentioned technical problems to a certain extent. The specific technical solution is as follows: A biomimetic integrated battery pack cover includes a plurality of shear-resistant structural layers and a plurality of impact-resistant structural layers stacked together, wherein the plurality of shear-resistant structural layers form an inner shear-resistant layer and the plurality of impact-resistant structural layers form an outer impact-resistant layer. Each of the shear-resistant structural layers has a first fiber structure, and each of the impact-resistant structural layers has a second fiber structure; Along the stacking direction of the shear-resistant structural layer and the impact-resistant structural layer, the layup angle of the first fiber structure between adjacent shear-resistant structural layers and the layup angle of the second fiber structure between adjacent impact-resistant structural layers are predetermined angles, the predetermined angles being less than 90°, so that each structural layer of the biomimetic integrated battery pack cover is formed as a spiral layup structure with continuous spiral changes at intervals of the predetermined angles.

[0005] Furthermore, the first fiber structure is formed of high-modulus and high-strength fibers, and the shear-resistant structural layer is formed by combining the first fiber structure and a high-hardness material matrix.

[0006] Furthermore, the second fiber structure is formed of high-toughness, high-fracture-strain fibers, and the impact-resistant structural layer is formed by combining the second fiber structure and a high-toughness material matrix.

[0007] Furthermore, a portion of the shear-resistant inner layer is provided with microcracks to allow for controllable rupture within a predetermined internal pressure range.

[0008] Furthermore, the biomimetic integrated battery pack cover also includes a heat-insulating and flame-retardant functional layer, which is attached to the inner side of the shear-resistant inner layer. and / or The biomimetic integrated battery pack cover also includes an outer protective layer, which is disposed on the outer side of the impact-resistant outer layer.

[0009] Furthermore, the thickness ratio of the shear-resistant inner layer to the impact-resistant outer layer is 1:1 to 1:3; and / or The number of shear-resistant structural layers is 4-8, and the number of impact-resistant structural layers is 4-24. and / or The predetermined angle is greater than 10 degrees and less than 30 degrees.

[0010] This application also provides a method for preparing a biomimetic integrated battery pack cover, comprising the following steps: S1: A first number of shear-resistant structural layers are formed by combining a first fiber structure layer with a high-hardness material matrix; a second number of impact-resistant structural layers are formed by combining a second fiber structure with a high-toughness material matrix. S2: The first number of shear-resistant structural layers and the second number of impact-resistant structural layers are spirally laid out at a predetermined angle, and hot-pressed and cured for a predetermined time under predetermined temperature and pressure. After cooling, the mold is opened and the shape is modified to form a stacked shear-resistant inner layer and an impact-resistant outer layer. S3: A heat-insulating and flame-retardant functional layer is attached to the inside of the shear-resistant inner layer; S4: Determine the pressure relief area of ​​the biomimetic integrated battery pack cover, and use laser etching to pre-create microcracks in the pressure relief area to ensure controllable rupture within the predetermined internal pressure range; S5: A polyurethane gel coating containing UV absorbers is sprayed onto the outside of the impact-resistant outer layer, and after high-temperature curing, it forms an exterior protective layer. S6: Trim and drill the cover plate of the biomimetic integrated battery pack, and then conduct airtightness, mechanical performance and thermal runaway tests in sequence.

[0011] Further, in step S1, the first fiber structure layer is carbon fiber, and the high-hardness material matrix is ​​epoxy resin or cyanate ester resin, with the first number being 6 layers; the second fiber structure is glass fiber, aramid fiber or UHMWPE fiber, and the high-toughness material matrix is ​​toughened epoxy or polyurethane, with the second number being 14 layers.

[0012] Furthermore, in step S2, the predetermined angle is 18°, so that each structural layer of the shear-resistant inner layer and the impact-resistant outer layer forms a spiral layup structure that is cyclically stacked in the manner of [0° / 18° / 36° / 54° / 72° / 90° / 108° / 126° / 144° / 162° / 180°]s along the stacking direction.

[0013] Furthermore, in step S3, the heat-insulating and flame-retardant functional layer is a 1.0 mm thick silica aerogel felt, which is bonded to the inner side of the shear-resistant inner layer by a high-temperature resistant adhesive.

[0014] Compared with existing technologies, the beneficial effects of this solution are: This application proposes a biomimetic integrated battery cover design based on the mantis shrimp claw structure, namely a shear-resistant inner layer + an impact-resistant outer layer. As the core stress-bearing layer of the cover material during thermal runaway, it can exhibit impact resistance and fracture toughness far exceeding that of traditional designs through the synergistic effect of "external hardness and internal toughness" and the energy dissipation mechanism of "spiral layering", effectively protecting the internal battery cells.

[0015] This application, through the aforementioned preparation method, can obtain a biomimetic integrated battery pack cover. From the perspective of biomimetic design, it introduces the unique "spiral layup" and "stiffness gradient" biomimetic structure of the mantis shrimp's claw rod. At the same time, it focuses on the functional integration of the battery pack cover, integrating the flame-retardant heat insulation layer, structural layer (shear-resistant inner layer and impact-resistant outer layer formed by biomimetic composite materials), pressure relief structure, and outer protective layer into one through material and process innovation. This achieves multi-functional synergy on a single component, thereby effectively improving the safety, lightweighting, and reliability of the battery pack, and providing a new technical path for the safety protection of power batteries. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the biomimetic integrated battery pack cover in this embodiment; Figure 2 This is a partial enlarged view along the thickness direction of the biomimetic integrated battery pack cover plate of this embodiment; Figure 3 This is a schematic diagram of the spiral arrangement structure of the biomimetic integrated battery pack cover in this embodiment; Figure 4 This is a flowchart of the preparation method of the biomimetic integrated battery pack cover plate in this embodiment.

[0017] icon: 1-Bionic structural layer; 11-Shear-resistant inner layer; 111-Shear-resistant structural layer; 12-Impact-resistant outer layer; 121-Impact-resistant structural layer; 2-Heat-insulating and flame-retardant functional layer; 3-Exterior protective layer. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] To address the issues of bulky structure and limited material properties caused by the overlapping functions of traditional battery pack covers, this application significantly improves the lightweight level, structural strength, and safety performance through innovative composite material design, thereby enhancing system reliability and durability.

[0020] The following is in conjunction with the appendix Figures 1 to 4 This application will specifically describe the structure, working principle, and preparation method of the biomimetic integrated battery pack cover.

[0021] When a single battery cell experiences thermal runaway, the battery pack cover plate needs to withstand high internal pressure loads with impact characteristics generated by violent chemical reactions in a very short time. In addition, it is accompanied by additional thermal stress due to its own uneven temperature field. This places higher demands on the battery pack cover plate structure's impact resistance to high internal pressure loads and its shear resistance to pressure loads and thermal stresses.

[0022] In biological structures, the mantis shrimp's chelicerae possess extremely high fracture toughness and impact resistance due to their spiral fiber periodic structure. Furthermore, due to the structural characteristics of its gradient material, the material transitions from extremely hard to relatively soft from the outside to the inside, forming impact-resistant zones and energy-dissipating zones, intelligently guiding, dispersing, and consuming impact energy.

[0023] To address the thermo-mechanical coupling conditions experienced by the top cover during thermal runaway of a single battery cell, this embodiment selects the unique spiral-shaped, gradient "hard on the outside, tough on the inside, spiral energy dissipation" structure of the mantis shrimp's claw rods and proposes a biomimetic integrated battery cover design based on the mantis shrimp's claw rod structure. This design consists of a heat-insulating and flame-retardant functional layer, a shear-resistant inner layer, and an impact-resistant outer layer. As the core stress-bearing layer of the cover material during thermal runaway, it can exhibit impact resistance and fracture toughness far exceeding traditional designs through the synergistic effect of "hard on the outside, tough on the inside" and the energy dissipation mechanism of "spiral layering," effectively protecting the internal battery cells.

[0024] Specifically, such as Figures 1 to 3 As shown, this embodiment proposes a biomimetic integrated battery pack cover, including a heat-insulating and flame-retardant functional layer 2, a plurality of shear-resistant structural layers 111 and a plurality of impact-resistant structural layers 121 stacked together. The plurality of shear-resistant structural layers 111 form an inner shear-resistant layer 11, and the plurality of impact-resistant structural layers 121 form an outer impact-resistant layer 12. The inner shear-resistant layer 11 is disposed inside the outer impact-resistant layer 12, and the heat-insulating and flame-retardant functional layer 2 is disposed inside the inner shear-resistant layer 11. The inner shear-resistant layer 11 and the outer impact-resistant layer 12 constitute the biomimetic structural layer 1.

[0025] like Figure 3 As shown, for the shear-resistant inner layer 11, each shear-resistant structural layer 111 has a first fiber structure, which is formed of high-modulus, high-strength fibers, such as carbon fiber. The shear-resistant structural layer 111 is formed by combining high-modulus, high-strength fibers with a high-hardness resin matrix (such as epoxy resin or cyanate ester resin). The shear-resistant inner layer 11 can be formed by stacking several shear-resistant structural layers 111. Based on the application scenario of the cover plate, the overall thickness of the cover plate structure, performance, and other comprehensive considerations, the shear-resistant inner layer 11 can include 4-8 layers of shear-resistant structural layers 111, for example, 6 layers, and each shear-resistant structural layer 111 has a certain fiber laying direction.

[0026] like Figure 3 As shown, for the impact-resistant outer layer 12, each impact-resistant structural layer 121 has a second fiber structure, which is formed of high-toughness, high-tensile-strain fibers, such as glass fiber, aramid fiber, and UHMWPE fiber. The impact-resistant structural layer 121 is formed by combining high-toughness, high-tensile-strain fibers with a high-toughness resin matrix (such as toughened epoxy or polyurethane). The impact-resistant outer layer 12 can be formed by stacking several impact-resistant outer layers 12, but considering the application scenario of the cover plate, the overall thickness of the structure, performance, etc., the impact-resistant outer layer 12 can include 4-24 layers of impact-resistant structural layers 121, for example, 14 layers. The thickness ratio of the shear-resistant inner layer 11 to the impact-resistant outer layer 12 can be 1:1-1:3, for example, 3:7, that is, when the shear-resistant structural layer 111 has 6 layers, the impact-resistant structural layer 121 has 14 layers. Each impact-resistant structural layer 121 also has a certain fiber laying direction.

[0027] It should be noted that the thickness and number of shear-resistant structural layers 111 and the thickness and number of impact-resistant outer layers 12 can be adjusted according to actual needs.

[0028] Each shear-resistant structural layer 111 and each impact-resistant structural layer 121 are formed into a single-layer prepreg by the composite of the corresponding fiber structure and the matrix. The structural layers are arranged in a spiral angle to form a spiral arrangement structure, and after curing, a biomimetic structural layer 1 is formed.

[0029] Specifically, such as Figure 3As shown, along the stacking direction of the shear-resistant structural layer 111 and the impact-resistant structural layer 121 (i.e., the thickness direction of the cover plate), the layup angles of the first fiber structures between adjacent shear-resistant structural layers 111, the layup angles of the second fiber structures between adjacent impact-resistant structural layers 121, and the angles between the first fiber structures of adjacent shear-resistant structural layers 111 and the second fiber structures of impact-resistant structural layers 121 are all predetermined angles, less than 90°, so that each structural layer of the biomimetic integrated battery pack cover plate forms a spiral layup structure with a continuous spiral change at predetermined angle intervals. That is, both the shear-resistant structural layer 111 and the impact-resistant structural layer 121 are arranged in a spiral manner, like an extremely dense, miniature "plywood" or "spiral staircase," with the fiber direction in each layer rotating at a fixed angle relative to the adjacent layer. This angle is not a traditional [0° / 90°]s orthogonal structure, but a spiral structure based on the continuous variation of the mantis shrimp's claws. This angle, i.e., the predetermined angle, is designed to be less than 90°, specifically greater than 10 degrees and less than 30 degrees, for example, 18°. That is, from the shear-resistant inner layer 11 to the impact-resistant outer layer 12, each structural layer is stacked in a cyclic manner in the pattern of [0° / 18° / 36° / 54° / 72° / 90° / 108° / 126° / 144° / 162° / 180°]s to form a spiral arrangement structure.

[0030] The spiral arrangement structure formed by the above-described cyclic stacking method exhibits a stiffness gradient between the shear-resistant inner layer 11 and the impact-resistant outer layer 12 in the thickness direction of the cover plate. The shear-resistant inner layer 11 forms a shear-resistant hard shell made of high-modulus material, which can effectively resist the shear impact formed by high-temperature and high-speed gas and solid particles during thermal runaway of the battery cell, preventing puncture. The impact-resistant outer layer 12 forms an impact-resistant deformation layer made of high-toughness material, which is the "tough core". When the shear-resistant inner layer 11 generates microcracks under impact, the deformation layer can effectively prevent the further propagation of cracks and absorb a large amount of energy through its own plastic deformation, preventing overall structural failure. Therefore, the shear-resistant inner layer 11 and the impact-resistant outer layer 12 together form a "hard outside and tough inside, spiral energy dissipation" structure. Through the synergistic effect of "hard outside and tough inside" and the energy dissipation mechanism of "spiral layup", it exhibits impact resistance and fracture toughness far exceeding that of traditional designs, effectively protecting the internal battery cell.

[0031] It should be noted that the fiber structure of each structural layer can be as follows: Figure 3The fiber structure shown can be arranged sequentially in the same direction in a single direction, or it can be arranged in multiple directions in different directions, as long as the adjacent structural layers are spirally interlaced at a predetermined angle to form a spiral layout structure. As for the spiral interlacing angle between adjacent structural layers, it is preferable that the spiral interlacing angle between any adjacent structural layers is consistent, although a small deviation is also acceptable, as long as it does not affect the formation of the spiral layout structure.

[0032] During molding, the multi-layer prepreg of the shear-resistant inner layer 11 is first cut, stacked, and spirally laid at a fixed angle. Then, the multi-layer prepreg of the impact-resistant outer layer 12 is cut, stacked, and spirally laid at a fixed angle on the basis of the structure of the shear-resistant inner layer 11. After that, it is placed in a hot autoclave and can be cured at 120°C and 1.5MPa pressure for 2 hours. After cooling to below 60°C, the mold is opened and the shape is modified to obtain the biomimetic structural layer 1 with spiral lay-up and gradient properties.

[0033] Furthermore, the traditional design of existing battery pack covers struggles to balance impact resistance and efficient pressure relief. Excessive cover strength can hinder internal pressure release, while explosion-proof valves are easily triggered or blocked by external impacts. Moreover, existing protection systems are mostly passive responses, unable to actively relieve pressure in the early stages of thermal runaway, posing a risk of lag. To address the issues of traditional battery pack covers' inability to balance impact resistance and pressure relief, as well as the lag in passive response, this embodiment incorporates microcracks in certain areas of the shear-resistant inner layer 11 to controllably rupture within a predetermined internal pressure range. Simulation analysis identifies high-stress areas (e.g., the center or edge) of the battery pack cover, which can serve as pressure relief areas. Pre-fabricated microcracks can be created in the corresponding pressure relief areas of the shear-resistant inner layer 11 using methods such as laser etching. This ensures that when a specific pressure is reached (e.g., 0.5-1.0 MPa), the pre-fabricated microcracks in the shear-resistant inner layer 11 rupture, resulting in rupture from the inside of the battery pack outwards, effectively releasing internal pressure. Simultaneously, the pressure relief response is more timely, enabling active pressure relief in the early stages of thermal runaway.

[0034] It should be noted that the pre-fabricated microcracks in the shear-resistant inner layer 11 of this embodiment are formed by laser etching or other methods after the shear-resistant inner layer 11 has been cured. The microcracks are set in the pressure relief area. Therefore, the setting of microcracks does not affect the overall shear resistance performance of the shear-resistant inner layer 11. The size of the microcracks is not limited, as long as they can achieve rupture under specific pressure.

[0035] In addition, the biomimetic integrated battery pack cover of this embodiment also includes a heat-insulating and flame-retardant functional layer 2. The heat-insulating and flame-retardant functional layer 2 can be a silica aerogel felt, which is firmly bonded to the inner surface of the shear-resistant inner layer 11 by a high-temperature resistant adhesive (such as silicone). This results in a structure of heat-insulating and flame-retardant functional layer 2 + shear-resistant inner layer 11 + impact-resistant outer layer 12, which serves as the core stress-bearing layer of the cover material during thermal runaway. This achieves the integration of impact resistance, active pressure relief and efficient heat insulation of the cover, significantly improving the lightweight level and safety performance.

[0036] In addition, the biomimetic integrated battery pack cover of this embodiment also includes an outer protective layer 3, which can be formed by spraying a certain thickness of polyurethane gel coating with added ultraviolet absorber onto the outer surface of the impact-resistant outer layer 12 and curing it.

[0037] This embodiment of the biomimetic integrated battery pack cover solves the problems of bulky structure, fragmented functions, and passive response of traditional battery pack covers from the source through a unique biomimetic integrated design concept. The innovation of this solution lies in the introduction of the "spiral layering" and "stiffness gradient" biomimetic structure unique to mantis shrimp claws from the perspective of biomimetic design. At the same time, it focuses on the functional integration of the battery pack cover, integrating the flame-retardant heat insulation layer (silica aerogel), structural layer (shear-resistant inner layer 11 and impact-resistant outer layer 12 formed by biomimetic composite materials), pressure relief structure (microcracks), and outer protective layer (polyurethane gel) into one through material and process innovation. This achieves multi-functional synergy on a single component, thereby effectively improving the safety, lightweight, and reliability of the battery pack, and providing a new technical path for the safety protection of power batteries.

[0038] This embodiment also provides a method for preparing a biomimetic integrated battery pack cover, including the following steps: S1: A first number of shear-resistant structural layers are formed by combining a first fiber structure layer with a high-hardness material matrix; a second number of impact-resistant structural layers are formed by combining a second fiber structure with a high-toughness material matrix. S2: The first number of shear-resistant structural layers and the second number of impact-resistant structural layers are spirally laid out at a predetermined angle, and hot-pressed and cured for a predetermined time under predetermined temperature and pressure. After cooling, the mold is opened and the shape is modified to form a stacked shear-resistant inner layer and an impact-resistant outer layer. S3: A heat-insulating and flame-retardant functional layer is attached to the inside of the shear-resistant inner layer; S4: Determine the pressure relief area of ​​the biomimetic integrated battery pack cover, and use laser etching to pre-create microcracks in the pressure relief area to ensure controllable rupture within the predetermined internal pressure range; S5: A polyurethane gel coating containing ultraviolet absorbers is sprayed onto the outside of the impact-resistant outer layer, and after high-temperature curing, it forms an outer protective layer 3; S6: Trim and drill the cover plate of the biomimetic integrated battery pack, and then conduct airtightness, mechanical performance and thermal runaway tests in sequence.

[0039] Taking a certain new energy vehicle power battery pack as an example, the battery pack has a rated voltage of 400V, a capacity of 100kWh, and uses square lithium-ion battery modules, with a total of 12 modules arranged in series. Figure 4 As shown, the battery pack cover is prepared using the following method: S1: Preparation of prepreg for shear-resistant and impact-resistant structural layers; Prepregs that form shear-resistant structural layers by combining carbon fiber with epoxy resin or cyanate ester resin; and prepregs that form impact-resistant structural layers by combining glass fiber, aramid fiber or UHMWPE fiber with toughened epoxy or polyurethane. S2: Forming and preparation of biomimetic shear-resistant and impact-resistant layers; Six shear-resistant structural layers and fourteen impact-resistant structural layers are stacked in a spiral layup pattern [0° / 18° / 36° / 54° / 72° / 90° / 108° / 126° / 144° / 162° / 180°]s to form a spiral layup structure. The structure is then hot-pressed and cured at 120°C and 1.5 MPa for 2 hours. After cooling, the structure is molded and modified to form a biomimetic structural layer composed of a shear-resistant inner layer and an impact-resistant outer layer with spiral layup and gradient properties. S3: Prepare a heat-insulating and flame-retardant functional layer; A 1.0 mm thick silica aerogel felt is used, which is firmly bonded to the inner surface of the biomimetic shear and impact resistant layer with silicone. S4: Preparation of directional pressure relief structure; The pressure relief area of ​​the biomimetic integrated battery pack cover was determined by simulation identification. Laser etching was used to pre-create microcracks in the corresponding pressure relief area of ​​the shear-resistant inner layer to ensure controllable rupture within the internal pressure range of 0.5~1.0 MPa. S5: Apply an exterior protective layer; A 0.2mm layer of polyurethane gel coating containing UV absorbers is sprayed onto the outside of the impact-resistant outer layer, and cured at 80℃ to form an exterior protective layer. S6: Post-processing and inspection; The cover plate of the biomimetic integrated battery pack was trimmed and drilled, and then tested for air tightness, mechanical properties and thermal runaway.

[0040] It should be noted that the simulation identification of the pressure relief area and the airtightness, mechanical properties and thermal runaway test of the biomimetic integrated battery pack cover in the above preparation method can be achieved using existing technical principles, so the specific process will not be described in this embodiment.

[0041] The biomimetic integrated battery pack cover obtained by the above preparation method, from the perspective of biomimetic design, introduces the unique "spiral layup" and "stiffness gradient" biomimetic structure of the mantis shrimp's claw rod. At the same time, focusing on the functional integration of the battery pack cover, the flame-retardant heat insulation layer (silica aerogel), structural layer (shear-resistant inner layer and impact-resistant outer layer formed by biomimetic composite materials), pressure relief structure (microcracks), and outer protective layer (polyurethane gel) are integrated into one through material and process innovation, realizing multi-functional synergy on a single component. This can effectively improve the safety, lightweighting, and reliability of the battery pack, providing a new technical path for the safety protection of power batteries.

[0042] The above examples illustrate the principles and implementation methods of the present invention. These embodiments are merely illustrative and intended to aid in understanding the method and core concepts of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the present invention.

Claims

1. A biomimetic integrated battery pack cover, characterized in that, It includes several shear-resistant structural layers and several impact-resistant structural layers stacked together, wherein the several shear-resistant structural layers form an inner shear-resistant layer and the several impact-resistant structural layers form an outer impact-resistant layer; Each of the shear-resistant structural layers has a first fiber structure, and each of the impact-resistant structural layers has a second fiber structure; Along the stacking direction of the shear-resistant structural layer and the impact-resistant structural layer, the layup angle of the first fiber structure between adjacent shear-resistant structural layers and the layup angle of the second fiber structure between adjacent impact-resistant structural layers are predetermined angles, the predetermined angles being less than 90°, so that each structural layer of the biomimetic integrated battery pack cover is formed as a spiral layup structure with continuous spiral changes at intervals of the predetermined angles.

2. The biomimetic integrated battery pack cover according to claim 1, characterized in that, The first fiber structure is formed of high-modulus and high-strength fibers, and the shear-resistant structural layer is formed by combining the first fiber structure and a high-hardness material matrix.

3. The biomimetic integrated battery pack cover according to claim 1, characterized in that, The second fiber structure is formed of high-toughness, high-fracture-strain fibers, and the impact-resistant structural layer is formed by combining the second fiber structure and a high-toughness material matrix.

4. The biomimetic integrated battery pack cover according to claim 1, characterized in that, The shear-resistant inner layer has microcracks in certain areas to allow for controlled rupture within a predetermined internal pressure range.

5. The biomimetic integrated battery pack cover according to claim 1, characterized in that, The biomimetic integrated battery pack cover also includes a heat-insulating and flame-retardant functional layer, which is attached to the inner side of the shear-resistant inner layer. and / or The biomimetic integrated battery pack cover also includes an outer protective layer, which is disposed on the outer side of the impact-resistant outer layer.

6. The biomimetic integrated battery pack cover according to claim 5, characterized in that, The thickness ratio of the shear-resistant inner layer to the impact-resistant outer layer is 1:1 to 1:3; and / or The number of shear-resistant structural layers is 4-8, and the number of impact-resistant structural layers is 4-24. and / or The predetermined angle is greater than 10 degrees and less than 30 degrees.

7. A method for preparing a biomimetic integrated battery pack cover, characterized in that, Includes the following steps: S1: A first number of shear-resistant structural layers are formed by combining a first fiber structure layer with a high-hardness material matrix; a second number of impact-resistant structural layers are formed by combining a second fiber structure with a high-toughness material matrix. S2: The first number of shear-resistant structural layers and the second number of impact-resistant structural layers are spirally laid out at a predetermined angle, and hot-pressed and cured for a predetermined time under predetermined temperature and pressure. After cooling, the mold is opened and the shape is modified to form a stacked shear-resistant inner layer and an impact-resistant outer layer. S3: A heat-insulating and flame-retardant functional layer is attached to the inside of the shear-resistant inner layer; S4: Determine the pressure relief area of ​​the biomimetic integrated battery pack cover, and use laser etching to pre-create microcracks in the pressure relief area to ensure controllable rupture within the predetermined internal pressure range; S5: A polyurethane gel coating containing UV absorbers is sprayed onto the outside of the impact-resistant outer layer, and after high-temperature curing, it forms an exterior protective layer. S6: Trim and drill the cover plate of the biomimetic integrated battery pack, and then conduct airtightness, mechanical performance and thermal runaway tests in sequence.

8. The method for preparing the biomimetic integrated battery pack cover according to claim 7, characterized in that, In step S1, the first fiber structure layer is carbon fiber, and the high-hardness material matrix is ​​epoxy resin or cyanate ester resin, with a first quantity of 6 layers; the second fiber structure is glass fiber, aramid fiber or UHMWPE fiber, and the high-toughness material matrix is ​​toughened epoxy or polyurethane, with a second quantity of 14 layers.

9. The method for preparing the biomimetic integrated battery pack cover according to claim 7, characterized in that, In step S2, the predetermined angle is 18°, so that the structural layers of the shear-resistant inner layer and the impact-resistant outer layer form a spiral layup structure that is cyclically stacked in the manner of [0° / 18° / 36° / 54° / 72° / 90° / 108° / 126° / 144° / 162° / 180°]s along the stacking direction.

10. The method for preparing the biomimetic integrated battery pack cover according to claim 7, characterized in that, In step S3, the heat-insulating and flame-retardant functional layer is a 1.0 mm thick silica aerogel felt, which is bonded to the inside of the shear-resistant inner layer with a high-temperature resistant adhesive.

Images