A battery thermal management composite structure, a battery pack and a composite structure manufacturing method

Abstract

This invention discloses a battery thermal management composite structure, a battery pack, and a method for manufacturing the composite structure. The composite layer is disposed between every two battery cells. It includes a thermally conductive and heat-absorbing layer and a thermally insulating layer bonded together. The thermally conductive and heat-absorbing layer has a first contact surface, and the thermally insulating layer has a second contact surface. Both the first and second contact surfaces are used to contact the battery cells. Microstructures are provided on both the first and second contact surfaces to form gas flow channels. The beneficial effect of this invention is that by setting the thermally conductive and heat-absorbing layer and the thermally insulating layer, and encapsulating and fixing them with an encapsulation layer, the thermally conductive and heat-absorbing layer and the thermally insulating layer respectively contact two adjacent battery cells. The microstructures on the first contact surface of the thermally conductive and heat-absorbing layer and the second contact surface of the thermally insulating layer form gas flow channels extending from one side of the contact surface to the other, thus improving the heat dissipation effect of the composite structure.

Description

Technical Field

[0001] This invention belongs to the field of battery thermal management technology, and particularly relates to a battery thermal management composite structure, a battery pack, and a method for manufacturing the composite structure. Background Technology

[0002] A battery pack typically consists of multiple cells arranged side by side. Since cells generate heat and undergo thermal expansion during use, a thermal management composite structure is usually required between every two adjacent cells to meet functions such as temperature equalization, insulation, and heat insulation.

[0003] In existing composite structures, the contact surface between the composite structure and the battery cell is a flat surface, meaning that the two are in surface contact. This results in the composite structure and the battery cell being too tightly bonded, which can easily hinder the thermal expansion of the battery cell. Furthermore, the tight contact surface can also affect the flow of gas and the overall heat dissipation effect. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a battery thermal management composite structure, a battery pack, and a method for manufacturing the composite structure, which can improve the heat dissipation effect between the composite structure and the battery cell.

[0005] To achieve the above objectives, the present invention employs the following technical solution: a battery thermal management composite structure, comprising: a composite layer disposed between every two battery cells, the composite layer comprising a thermally conductive and temperature-equalizing layer and a thermally insulating layer bonded together, the thermally conductive and temperature-equalizing layer comprising a first contact surface, the thermally insulating layer comprising a second contact surface, the first and second contact surfaces being used to contact the battery cells, both the first and second contact surfaces being provided with microstructures, the microstructures being used to form gas flow channels; and an encapsulation layer encapsulated on the outer periphery of the composite layer.

[0006] Optionally, the microstructure includes protrusions, and multiple protrusions are spaced apart on both the first and second contact surfaces.

[0007] Optionally, the microstructure includes grooves, with multiple grooves spaced parallel to each other on the first and second contact surfaces. The grooves on the first contact surface extend from one side of the first contact surface to the other side, and the grooves on the second contact surface extend from one side of the second contact surface to the other side. Each groove includes multiple V-shaped grooves, and the multiple V-shaped grooves are connected in sequence.

[0008] Optionally, the thermally conductive and temperature-equalizing layer is a first composite material, which is magnesium oxide microparticle diffusion engineering plastic or graphene-reinforced engineering plastic, and the thermal insulation layer is a second composite material, which is fumed silica or nanoporous aerogel.

[0009] Microstructures transform surface contact into point or line contact. Under the same pressure, the pressure at the contact point increases, causing the microstructure tip to slightly press into the flexible layer on the cell surface, forming an "embedded" fit. The microstructure undergoes minute elastic deformation under pressure, adaptively conforming to the microscopic unevenness of the cell surface. During assembly, air between the microstructures is squeezed out, creating localized micro-negative pressure, enhancing the fit. During battery charging and discharging, the cell thickness changes, and the microstructure absorbs these dimensional changes through elastic deformation, maintaining a continuous fit. The gaps between the microstructures are interconnected, forming a continuous airflow network. Microchannels generate capillary action, promoting airflow. When the battery heats up, the air within the channels rises, creating natural convection circulation.

[0010] A battery pack includes the battery thermal management composite structure, comprising a plurality of spaced-apart battery cells, wherein the battery thermal management composite structure is disposed between every two adjacent battery cells, and the side of the battery cell is in contact with the encapsulation layer.

[0011] This device integrates multiple functions such as thermal conductivity and temperature equalization, thermal insulation, and encapsulation protection into one unit. It can achieve encapsulation and fixation without additional adhesive layers, simplifying the overall structure, reducing the complexity of battery pack design, meeting the requirements for thermal equalization and insulation between cells, and ensuring that the battery pack is in a stable thermal environment, thereby improving battery pack performance.

[0012] A method for manufacturing a composite structure for manufacturing the battery thermal management composite structure includes the following steps: providing sheet-like first composite material and second composite material, and cleaning and drying the first composite material and second composite material; a processing step, processing microstructures on the surfaces to be processed of the first composite material and second composite material to form a composite layer, and processing an encapsulation layer on the outer periphery of the first composite material and second composite material.

[0013] Optionally, the processing steps specifically include: stamping multiple protrusions or multiple grooves on the surfaces to be processed of the first composite material and the second composite material to form the thermally conductive and heat-insulating layer; providing an upper PET film and a lower PET film, and stacking them in the order of upper PET film, thermally conductive and heat-insulating layer, and lower PET film; placing the stacked materials in a hot press for hot pressing, so that the upper PET film and lower PET film melt and fuse with the protrusions or grooves to form an integrated structure with an encapsulation layer; demolding and cooling, and removing the integrated structure.

[0014] Optionally, the integrated structure can be cut to fit the cell size; the cut integrated structure is placed in a hot press and the four sides of the integrated structure are heat-sealed in sequence.

[0015] Optionally, the processing steps specifically include: cutting the sheet-like first composite material and second composite material to fit the cell size; providing an upper PET film and a lower PET film, and stacking them in the order of upper PET film, first composite material, second composite material, and lower PET film; placing the stacked materials in a hot press for hot pressing, so that the upper PET film and lower PET film wrap the first composite material and second composite material to form a flat composite sheet with an encapsulation layer; fixing the flat composite sheet on a laser worktable, and using laser scanning to locally remove material from both sides of the composite sheet in sequence to form the microstructure.

[0016] Optionally, the processing steps specifically include: preparing a transfer template, the transfer template having a concave portion complementary to the shape of the protrusion or a stamping portion complementary to the shape of the groove; cutting the sheet-like first composite material and second composite material to adapt to the cell size; providing an upper PET film and a lower PET film, and stacking them in the order of upper PET film, first composite material, second composite material, and lower PET film; placing the stacked materials in a hot press for hot pressing, so that the upper PET film and lower PET film wrap the first composite material and the second composite material to form a flat composite sheet with an encapsulation layer; fixing the flat composite sheet on a worktable, heating the transfer template and pressing the transfer template against the flat composite sheet, causing local softening of its surface to form the microstructure.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: 1. By setting a thermally conductive and heat-insulating layer and a thermally insulating layer, and using an encapsulation layer to encapsulate and fix the thermally conductive and heat-insulating layer, the thermally conductive and heat-insulating layer and the thermally insulating layer are respectively in contact with two adjacent battery cells. Microstructures are set on the first contact surface of the thermally conductive and heat-insulating layer and the second contact surface of the thermally insulating layer, forming a gas flow channel extending from one side of the contact surface to the other side of the contact surface, which improves the heat dissipation effect of the composite structure.

[0018] 2. By setting microstructures on the contact surface of the battery cell, the surface contact between the composite structure and the battery cell is transformed into point contact or line contact. Under the same pressure, the pressure at the contact point increases, and the microstructure can undergo slight elastic deformation under pressure, thereby adaptively fitting the surface of the battery cell and avoiding the situation where the composite structure and the battery cell are too tightly bonded, hindering the thermal expansion of the battery cell. Attached Figure Description

[0019] Figure 1 The image shown is a side view of the composite layer and the battery cell of the present invention; Figure 2 The image shown is a side enlarged view of the composite layer of the present invention; Figure 3 The figure shown is a schematic diagram of the overall structure of the protrusion of the present invention; Figure 4 The diagram shown is a schematic representation of the overall structure of the trench of the present invention. Figure 5 The image shown is a side view of the protrusion of the present invention.

[0020] In the diagram: 1. Composite layer; 2. Battery cell; 101. Thermally conductive and temperature-regulating layer; 102. Thermal insulation layer; 103. Microstructure; 1011, First contact surface; 1021, Second contact surface; 1031, Protrusion; 1032, Groove. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not 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 the invention. Furthermore, the terms "first," "second," etc., 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 with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Example 1 Reference Figures 1 to 5This embodiment provides a battery thermal management composite structure, specifically including: a composite layer 1, which is disposed between every two battery cells 2, the composite layer 1 including a thermally conductive and temperature-equalizing layer 101 and a thermally insulating layer 102 attached to each other, the thermally conductive and temperature-equalizing layer 101 including a first contact surface 1011, the thermally insulating layer 102 including a second contact surface 1021, the first contact surface 1011 and the second contact surface 1021 being used to contact the battery cell 2, and both the first contact surface 1011 and the second contact surface 1021 being provided with microstructures 103, the microstructures 103 being used to form gas flow channels; and an encapsulation layer, which is encapsulated on the outer periphery of the composite layer 1.

[0025] The total thickness of composite layer 1 is 0.5-3 mm. The encapsulation layer includes two PET films, each with a thickness of 0.05-0.1 mm, a temperature resistance of ≥150℃, and resistance to electrolyte corrosion. The two PET films are encapsulated on the non-adhesive surfaces of the thermally conductive and heat-dissipating layer 101 and the thermally insulating layer 102, and the two PET films are connected to seal and encapsulate the thermally conductive and heat-dissipating layer 101 and the thermally insulating layer 102. The PET films are bonded to the microstructure 103.

[0026] The microstructure 103 includes protrusions 1031, and multiple protrusions 1031 are distributed at intervals on both the first contact surface 1011 and the second contact surface 1021.

[0027] The microstructure 103 includes a groove 1032. The first contact surface 1011 and the second contact surface 1021 are both provided with a plurality of grooves 1032 at parallel intervals. The groove 1032 located on the first contact surface 1011 extends from one side of the first contact surface 1011 to the other side, and the groove 1032 located on the second contact surface 1021 extends from one side of the second contact surface 1021 to the other side. Each groove 1032 includes a plurality of V-shaped grooves, and the plurality of V-shaped grooves are connected in sequence.

[0028] like Figure 3 and Figure 5 As shown, the protrusion 1031 is hemispherical or cylindrical, with a height of 0.05-0.3 mm, a diameter of 0.2-0.8 mm, and a distance of 0.5-2 mm between any two protrusions 1031.

[0029] like Figure 4 As shown, the groove 1032 has a depth of 0.1-0.4 mm, a width of 0.2-0.8 mm, a spacing of 0.5-2 mm between two grooves 1032, and an inner angle of 60°-120° for the V-shaped groove. The groove 1032 can also be composed of multiple sequentially connected U-shaped grooves.

[0030] On the first contact surface 1011 or the second contact surface 1021, only the protrusion 1031 may be provided, or only the groove 1032 may be provided, or both the protrusion 1031 and the groove 1032 may be provided.

[0031] like Figure 3 and Figure 4 As shown, multiple gas channels are formed, and the multiple gas channels are distributed in parallel and spaced along the horizontal direction. The multiple gas channels formed by the protrusion 1031 are connected, while the multiple gas channels formed by the groove 1032 are independent of each other. The gas channels extend from one side of the first contact surface 1011 or the second contact surface 1021 to the other side, realizing air circulation and improving heat dissipation performance.

[0032] The thermally conductive and temperature-equalizing layer 101 is a first composite material, which is magnesium oxide microparticle diffusion engineering plastic or graphene-reinforced engineering plastic. The thermal insulation layer 102 is a second composite material, which is fumed silica or nanoporous aerogel.

[0033] The thermally conductive and temperature-equalizing layer 101 has a thickness of 0.15mm-0.3mm, and the thermal insulation layer 102 has a thickness of 0.7-0.9mm.

[0034] The thermal conductivity of the heat-conducting and temperature-equalizing layer 101 is ≥1W / (m·K), and the breakdown voltage is ≥3000V.

[0035] The thermal conductivity of the heat insulation layer 102 is ≤0.02W / (m·K), and the temperature resistance is ≥200℃.

[0036] The thermally conductive and temperature-equalizing layer 101 is made of magnesium oxide microparticle-diffused engineering plastic or graphene-reinforced engineering plastic, which has both high thermal conductivity and high insulation properties. The thermal insulation layer 102 is made of fumed silica or nanoporous aerogel, which effectively blocks heat conduction and solves the problem of insufficient thermal conductivity and insulation of traditional composite structures.

[0037] The PET film thermoforming integrated encapsulation avoids the aging and debonding risks associated with traditional adhesive bonding methods. The edges are automatically sealed to prevent delamination and heat leakage. The overall structure is stable, resistant to electrolyte corrosion, and suitable for long-term battery use.

[0038] This solution also has the following advantages over existing technologies: 1. Enhanced fit: The microstructure 103 transforms surface contact into point or line contact. Under the same pressure, the pressure at the contact point increases, causing the tip of the microstructure 103 to be slightly pressed into the flexible layer on the surface of the cell 2, forming an "embedded" fit. The microstructure 103 undergoes slight elastic deformation under pressure, adaptively fitting the microscopic unevenness of the cell surface. During assembly, the air between the microstructures 103 is squeezed out, forming a local micro-negative pressure, enhancing the fit. During battery charging and discharging, the thickness of the cell 2 changes, and the microstructure 103 can absorb the dimensional changes through elastic deformation, maintaining a continuous fit.

[0039] 2. Improved air circulation: The gaps between the microstructures 103 are interconnected, forming a through-flow air circulation network; the microchannels generate capillary action, promoting airflow; when the battery heats up, the air in the channels is heated and rises, forming a natural convection circulation.

[0040] Example 2 Reference Figures 1 to 5 This embodiment provides a battery pack, which includes a battery thermal management composite structure, specifically including multiple spaced-apart battery cells 2. A battery thermal management composite structure is provided between every two adjacent battery cells 2, and the side of the battery cell 2 is in contact with the encapsulation layer.

[0041] This solution integrates multiple functions such as thermal conductivity and temperature equalization, thermal insulation, and encapsulation protection into one unit. It can achieve encapsulation and fixation without additional adhesive layers, simplifying the overall structure, reducing the complexity of battery pack design, meeting the requirements for thermal equalization and insulation between cells, and achieving the requirement of the battery pack being in a steady-state thermal environment, thereby improving battery pack performance.

[0042] Tests showed that, in a 1C charge-discharge cycle, the maximum temperature difference between cells using this solution decreased from 8°C to below 3°C, the insulation resistance was ≥100MΩ, the thermal runaway propagation time was delayed by ≥30%, and the system cycle life was improved by approximately 15%.

[0043] Example 3 Reference Figures 1 to 5 This embodiment provides a composite structure manufacturing method for manufacturing a battery thermal management composite structure, specifically including the following steps: providing sheet-like first composite material and second composite material, and cleaning and drying the first composite material and second composite material; processing steps, processing microstructures 103 on the surfaces to be processed of the first composite material and second composite material to form a composite layer 1, and processing an encapsulation layer on the outer periphery of the first composite material and second composite material.

[0044] The surface to be processed is the side of the first composite material and the second composite material closest to the cell 2.

[0045] The processing steps can be done in various ways, for example: One specific processing step includes: stamping multiple protrusions 1031 or multiple grooves 1032 on the surfaces to be processed of the first composite material and the second composite material to form a thermally conductive and temperature-regulating layer 101 and a thermally insulating layer 102; providing an upper PET film and a lower PET film, and stacking them in the order of upper PET film, thermally conductive and temperature-regulating layer 101, thermally insulating layer 102, and lower PET film; placing the stacked materials in a hot press for hot pressing, so that the upper PET film and the lower PET film melt and fuse with the protrusions 1031 or grooves 1032 to form an integrated structure with an encapsulation layer; demolding and cooling, and removing the integrated structure.

[0046] It also includes cutting the integrated structure to fit the size of cell 2; placing the cut integrated structure in a hot press and performing secondary heat sealing on the four sides of the integrated structure in sequence.

[0047] The hot pressing temperature of the hot press is 140-160℃, the pressure is 0.8-1.5MPa, and the hot pressing time is 20-40 seconds, to ensure that the PET film melts and flows fully into the protrusion 1031 or groove 1032.

[0048] While cutting the integrated structure, it is also necessary to punch holes and slot the integrated structure according to the poles and sampling points of cell 2.

[0049] One of the processing steps specifically includes: cutting the sheet-like first composite material and second composite material to fit the size of the battery cell 2; providing an upper PET film and a lower PET film, and stacking them in the order of upper PET film, first composite material, second composite material, and lower PET film; placing the stacked materials in a hot press for hot pressing, so that the upper PET film and lower PET film wrap the first composite material and second composite material to form a flat composite sheet with an encapsulation layer; fixing the flat composite sheet on a laser worktable, and using laser scanning to locally remove material from both sides of the composite sheet in sequence to form a microstructure 103.

[0050] A carbon dioxide laser is used to perform laser scanning on a flat composite sheet. The laser scanning power is 10-30W, the laser scanning speed is 500-2000mm / s, and the laser scanning frequency is 5-20kHz.

[0051] One of the processing steps specifically includes: preparing a transfer template, the transfer template having a concave portion complementary to the shape of the protrusion 1031 or a stamping portion complementary to the shape of the groove 1032; cutting the sheet-like first composite material and second composite material to fit the size of the battery cell 2; providing an upper PET film and a lower PET film, and stacking them in the order of upper PET film, first composite material, second composite material, and lower PET film; placing the stacked materials in a hot press for hot pressing, so that the upper PET film and lower PET film wrap the first composite material and the second composite material to form a flat composite sheet with an encapsulation layer; fixing the flat composite sheet on a worktable, heating the transfer template and pressing the transfer template against the flat composite sheet, causing local softening of its surface to form a microstructure 103.

[0052] Heat the transfer template to 120-140℃, and the contact pressure between the transfer template and the flat composite sheet surface is 0.3-0.8MPa, with a contact time of 5-15 seconds.

[0053] One of the processing steps specifically includes: preparing an embossing roller, the embossing roller having a roller body recess that complements the shape of the protrusion 1031 or a roller body stamping portion that complements the shape of the groove 1032; cutting the sheet-like first composite material and second composite material to fit the size of the battery cell 2; providing an upper PET film and a lower PET film, and stacking them in the order of upper PET film, first composite material, second composite material, and lower PET film; placing the stacked material in a hot press for hot pressing, so that the upper PET film and lower PET film wrap the first composite material and the second composite material to form a flat composite sheet with an encapsulation layer; fixing the flat composite sheet on a worktable, using a heating roller to raise the temperature of the surface to be processed, then using an embossing roller to press out the shape of the protrusion 1031 or groove 1032 on the surface to be processed, and finally using a cooling roller to cool down, forming a microstructure 103.

[0054] The temperature of the heating roller is 130-150℃, the linear speed of the heating roller, embossing roller, and cooling roller is 1-5m / min, the rolling pressure is 0.5-1.5MPa, and the temperature of the cooling roller is 10-20℃. This process is simple, suitable for large-scale production, and can be produced using continuous rolling. It is suitable for automated assembly lines, with low manufacturing costs and high efficiency.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A battery thermal management composite structure, characterized in that, include: A composite layer (1) is provided between every two battery cells (2). The composite layer (1) includes a thermally conductive and temperature-equalizing layer (101) and a thermally insulating layer (102) that are attached together. The thermally conductive and temperature-equalizing layer (101) includes a first contact surface (1011), and the thermally insulating layer (102) includes a second contact surface (1021). The first contact surface (1011) and the second contact surface (1021) are used to contact the battery cells (2). The first contact surface (1011) and the second contact surface (1021) are both provided with microstructures (103). The microstructures (103) are used to form gas flow channels. The encapsulation layer is encapsulated on the outer periphery of the composite layer (1).

2. The battery thermal management composite structure according to claim 1, characterized in that, The microstructure (103) includes protrusions (1031), and the first contact surface (1011) and the second contact surface (1021) are each provided with a plurality of protrusions (1031) at intervals.

3. The battery thermal management composite structure according to claim 1 or 2, characterized in that, The microstructure (103) includes grooves (1032). The first contact surface (1011) and the second contact surface (1021) are both provided with a plurality of grooves (1032) at parallel intervals. The grooves (1032) located on the first contact surface (1011) extend from one side of the first contact surface (1011) to the other side. The grooves (1032) located on the second contact surface (1021) extend from one side of the second contact surface (1021) to the other side. Each groove (1032) includes a plurality of V-shaped grooves, and the plurality of V-shaped grooves are connected in sequence.

4. The battery thermal management composite structure according to claim 3, characterized in that, The thermally conductive and temperature-equalizing layer (101) is a first composite material, which is magnesium oxide microparticle diffusion engineering plastic or graphene-reinforced engineering plastic. The thermal insulation layer (102) is a second composite material, which is fumed silica or nanoporous aerogel.

5. A battery pack, characterized in that, The battery thermal management composite structure as described in any one of claims 1-4 includes a plurality of spaced-apart cells (2), with the battery thermal management composite structure disposed between every two adjacent cells (2), and the side of the cell (2) is in contact with the encapsulation layer.

6. A method for manufacturing a composite structure, characterized in that, The method for manufacturing the battery thermal management composite structure as described in any one of claims 1-4 includes the following steps: A first composite material and a second composite material in sheet form are provided, and the first composite material and the second composite material are cleaned and dried. The processing steps involve processing microstructures (103) on the surfaces to be processed of the first composite material and the second composite material to form a composite layer (1), and processing an encapsulation layer on the outer periphery of the first composite material and the second composite material.

7. The method for manufacturing a composite structure according to claim 6, characterized in that, The processing steps specifically include: Multiple protrusions (1031) or multiple grooves (1032) are stamped on the surfaces to be processed of the first composite material and the second composite material to form the thermally conductive and temperature-equalizing layer (101) and the thermal insulation layer (102). An upper PET film and a lower PET film are provided and stacked in the following order: upper PET film, thermally conductive and temperature-equalizing layer (101), thermal insulation layer (102), and lower PET film. The stacked materials are placed in a hot press for hot pressing, so that the upper PET film and the lower PET film melt and fuse with the protrusion (1031) or the groove (1032) to form an integrated structure with an encapsulation layer. Demolding and cooling allow for the removal of the integrated structure.

8. The method for manufacturing a composite structure according to claim 7, characterized in that, It also includes cutting the integrated structure to fit the cell (2) size; The cut integrated structure is placed in a hot press, and the four sides of the integrated structure are heat-sealed in sequence.

9. The method for manufacturing a composite structure according to claim 6, characterized in that, The processing steps specifically include: The sheet-like first and second composite materials are cut to fit the size of the battery cell (2); Provide an upper PET film and a lower PET film, which are stacked in the order of upper PET film, first composite material, second composite material, and lower PET film; The stacked materials are placed in a hot press for hot pressing, so that the upper PET film and the lower PET film wrap the first composite material and the second composite material to form a flat composite sheet with an encapsulation layer. The flat composite sheet is fixed on the laser worktable, and the two sides of the composite sheet are removed in sequence by laser scanning to form the microstructure (103).

10. The method for manufacturing a composite structure according to claim 6, characterized in that, The processing steps specifically include: Prepare a transfer template, the transfer template having a concave portion that is complementary to the shape of the protrusion (1031) or a stamping portion that is complementary to the shape of the groove (1032); The sheet-like first and second composite materials are cut to fit the size of the battery cell (2); Provide an upper PET film and a lower PET film, which are stacked in the order of upper PET film, first composite material, second composite material, and lower PET film; The stacked materials are placed in a hot press for hot pressing, so that the upper PET film and the lower PET film wrap the first composite material and the second composite material to form a flat composite sheet with an encapsulation layer. The flat composite sheet is fixed on the worktable, the transfer template is heated and pressed against the flat composite sheet, causing local softening of its surface and forming the microstructure (103).

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