Battery pack upper housing and battery pack

Abstract

The application relates to the technical field of batteries and discloses a battery pack upper shell and a battery pack, wherein the battery pack upper shell comprises a shell body, a heat protection layer is attached to the area of the inner surface of the shell body opposite to the battery cell, the shell body is made of a composite material, the thickness of the shell body is T1, the thickness of the heat protection layer is T2, and 0.9 <= T2 / T1 <= 2 is met. The shell body is made of a composite material, the overall weight is relatively light, the lightweight design is facilitated, the heat protection layer is attached to the area of the inner surface of the shell body opposite to the battery cell, and the ratio of the thickness of the heat protection layer to the thickness of the shell body is controlled to be within a proper range, the heat protection capability and the structural rigidity of the battery pack can be improved, the pressure resistance of the upper shell during thermal runaway is improved, and the safety performance is good.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to the upper casing of a battery pack and the battery pack itself. Background Technology

[0002] Currently, traditional gasoline-powered vehicles are being gradually replaced by new energy vehicles, and the safety performance of their power batteries is a key focus of the market. A battery pack typically consists of a lower casing, battery modules, a battery management system (BMS), and an upper casing. The upper casing, as a crucial structural and protective component of the battery pack, primarily functions to seal and protect the internal battery cells and high-voltage electrical components from external moisture, dust, mechanical impact, and collisions.

[0003] To meet the safety requirements of battery packs, the upper shell of existing battery packs is mostly made of sheet metal. However, sheet metal upper shells are heavy, which is not conducive to the overall vehicle weight reduction and can also affect the overall vehicle range.

[0004] In addition, regarding the safety performance of power batteries, thermal runaway protection of battery packs has become a key focus of research and development in the industry. Currently, the thermal runaway protection structure is mainly concentrated on the lower shell, while the upper shell is generally designed separately from the fireproof layer, resulting in poor thermal protection capability of the upper shell. Summary of the Invention

[0005] In view of this, the present invention provides a battery pack upper housing and a battery pack to solve the problem of poor thermal protection capability of existing battery pack upper housings.

[0006] In a first aspect, the present invention provides a battery pack housing, comprising: a housing body, wherein a thermal protection layer is attached to the inner surface of the housing body in the region opposite to the battery cell, the housing body is made of a composite material, the thickness of the housing body is T1, and the thickness of the thermal protection layer is T2, satisfying 0.9≤T2 / T1≤2.

[0007] Beneficial Effects: The battery pack casing of this invention is made of composite material, resulting in a lighter overall weight, which facilitates lightweight design. A thermal protection layer is attached to the inner surface of the casing, in the area opposite the battery cells. By controlling the ratio of the thermal protection layer thickness to the casing thickness within a suitable range, the thermal protection capability and structural strength of the battery pack can be improved, thereby enhancing the casing's pressure resistance during thermal runaway and providing better safety performance. If the T2 / T1 value is too small, the casing is easily burned through during thermal runaway. If the T2 / T1 value is too large, the casing is thicker, occupies more space, and has higher operating costs.

[0008] In one alternative implementation, 1 mm ≤ T1 ≤ 1.5 mm, and 0.8 mm ≤ T2 ≤ 2 mm.

[0009] Beneficial effects: By controlling the thickness of the casing within a suitable range, the significant increase in the total weight and material cost of the battery pack due to excessive casing thickness can be effectively avoided. This thickness range ensures that the casing has sufficient mechanical strength and rigidity to withstand mechanical impacts, vibrations, and stresses generated by the expansion of internal battery cells during installation and use. This provides reliable structural protection for the internal battery cells and prevents safety hazards such as short circuits caused by casing deformation. Controlling the casing thickness within a suitable range further enhances the structural strength of the casing while providing thermal protection.

[0010] In one optional embodiment, a conductive layer is provided on the inner surface of the shell body in the area corresponding to the BMS. The conductive layer covers the surface of the BMS, and the thickness of the conductive layer is T3, which satisfies 8≤T1 / T3≤13 and 0.12 mm≤T3≤0.18 mm.

[0011] Beneficial effects: A conductive layer is provided on the inner surface of the casing in the area corresponding to the BMS, which can improve the battery pack's electromagnetic interference resistance. If the value of T1 / T3 is too small, the electromagnetic interference resistance is poor; if the value of T1 / T3 is too large, the conductive layer is too thick, occupying a large space and wasting material.

[0012] In one optional embodiment, the shell body includes a bottom plate and side plates surrounding the bottom plate, the bottom plate and the side plates forming an accommodating space, the accommodating space accommodating at least the explosion-proof valve of the battery cell, and the thermal protection layer is disposed on the inner surface of the bottom plate and disposed opposite to the explosion-proof valve.

[0013] Beneficial effect: In the event of thermal runaway, a large amount of heat is ejected from the explosion-proof valve. Placing the thermal protection layer opposite to the explosion-proof valve can effectively prevent the shell body from being burned through during thermal runaway.

[0014] In one optional embodiment, the width of the thermal protection layer along the Y direction is W1, and the width of the battery cell along the Y direction is W2, satisfying 0.08≤W2 / W1≤0.12 and 200 mm≤W1≤250 mm.

[0015] Beneficial effects: By controlling W2 / W1 within a suitable range, it is possible to ensure that the thermal protection layer fully covers the high-temperature fluid ejected from the explosion-proof valve during thermal runaway, thereby effectively isolating thermal shock, protecting the integrity of the base plate, preventing the base plate from cracking due to high temperature, and significantly improving the safety performance of the battery pack.

[0016] In one optional embodiment, the length of the battery cell along the X direction is L1, and the width of the explosion-proof valve along the X direction is W3, satisfying 0.1≤W3 / L1≤0.13, 180 mm≤L1≤300 mm, and 23 mm≤W3≤28 mm.

[0017] Beneficial effects: By controlling W3 / L1 within a suitable range, the high pressure can be released in time by using the explosion-proof valve during thermal runaway, effectively suppressing the risk of shell cracking and improving the reliability of the battery pack.

[0018] In one optional embodiment, the side plate is folded along the XY plane to form a flange, and a transition arc is provided between the side plate and the flange. The thickness of the flange is T4, the radius of the outer rounded corner of the transition arc is R1, and the radius of the inner rounded corner of the transition arc is R2, satisfying R2=R1+T4, 3 mm≤T4≤4 mm, 5 mm≤R1≤8 mm, and 8 mm≤R2≤12 mm.

[0019] Beneficial effects: The flanges around the side panels and the transition arc between them effectively enhance the structural strength of the shell body and prevent the bottom plate from cracking under stress. Since R2 = R1 + T4, the inner and outer contours of the transition arc form a thickened arc, which facilitates the smooth transfer and dispersion of structural stress and reduces stress concentration.

[0020] Furthermore, by controlling T4 within a suitable range, sufficient structural strength of the flange can be ensured, providing a reliable load-bearing foundation for the fastening connection between the upper and lower shells. By controlling R1 within a suitable range, excessively "blunt" transition arcs are prevented from occupying too much internal or external space. By controlling R2 within a suitable range, the structural strength at the transition arc can be further enhanced.

[0021] In one optional embodiment, a first transition fillet is provided between the side plate and the bottom plate, the radius of the first transition fillet being R3 along the X direction. The bottom plate is provided with a plurality of reinforcing ribs protruding in the Z direction at intervals. A second transition fillet is provided between the reinforcing ribs and the bottom plate, the radius of the second transition fillet being R4, satisfying R3 / R4≥2, 20mm≤R3≤22 mm, and 10 mm≤R4≤13 mm.

[0022] Beneficial effects: Multiple reinforcing ribs spaced at intervals on the base plate enhance its structural strength, preventing tearing under excessive pressure during thermal runaway. A first transition fillet between the side plates and the base plate withstands impacts, vibrations, and pressure from the internal battery cells, preventing stress concentration at the connection point. A second transition fillet between the reinforcing ribs and the base plate further prevents stress concentration at the connection point. Controlling R3 / R4 ≥ 2 ensures smooth stress transfer, further reducing the risk of base plate cracking.

[0023] Furthermore, by controlling R3 within a suitable range, the maximum stress concentration factor at the connection between the side plate and the bottom plate can be significantly reduced. By controlling R4 within a suitable range, it can be ensured that the stiffeners can exist in a steeper and more effective "deep rib" form, thereby providing maximum bending stiffness within a limited layout space.

[0024] In one optional embodiment, the height of the reinforcing rib along the Z direction is T5, satisfying 1.5≤T5 / T2≤2.5, 2 mm≤T5≤3 mm.

[0025] Beneficial effects: By controlling T5 / T2 within a suitable range, it is possible to meet the requirements of lightweight battery pack while taking into account thermal protection performance and structural rigidity requirements, effectively enhancing the deformation resistance of the shell body.

[0026] Secondly, the present invention also provides a battery pack, comprising:

[0027] The aforementioned battery pack housing;

[0028] The lower housing connects to the upper housing of the battery pack to form a closed installation space;

[0029] At least one battery cell is installed in the installation space, and the explosion-proof valve of the battery cell faces the inner surface of the upper housing and is disposed opposite to the thermal protection layer.

[0030] Beneficial Effects: The battery pack of this invention features a casing made of composite material, resulting in a lighter overall weight and facilitating lightweight design. A thermal protection layer is attached to the inner surface of the casing, opposite the battery cells. By controlling the ratio of the thermal protection layer's thickness to the casing's thickness within a suitable range, the battery pack's thermal protection capability and structural strength are improved, thereby enhancing the casing's pressure resistance during thermal runaway and providing better safety performance. If the T2 / T1 value is too small, the casing is prone to burn-through during thermal runaway. If the T2 / T1 value is too large, the casing becomes thicker, occupying more space and increasing operating costs. Furthermore, the explosion-proof valve faces the inner surface of the casing and is positioned opposite the thermal protection layer, effectively preventing the casing from burning through during thermal runaway. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a battery pack upper casing according to an embodiment of the present invention;

[0033] Figure 2 This is an exploded view of the upper casing of a battery pack according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of a battery pack upper casing from another perspective according to an embodiment of the present invention;

[0035] Figure 4 This is a top view of the upper casing of a battery pack according to an embodiment of the present invention;

[0036] Figure 5 for Figure 4 Cross-sectional view of the shell body at point AA;

[0037] Figure 6 for Figure 5 A magnified view of a portion of the image;

[0038] Figure 7 This is a top view of a battery cell in a battery pack according to an embodiment of the present invention.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Shell body; 101. Bottom plate; 102. Side plate; 103. Flanged edge; 104. Transition arc segment; 105. First transition fillet; 106. Reinforcing rib; 107. Second transition fillet; 2. Thermal protection layer; 3. Conductive layer; 4. Battery cell; 401. Explosion-proof valve. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] In embodiments of the present invention, a "battery pack" is formed by combining a certain number of battery cells into a battery module and placing it in a housing to protect the battery cells from external impacts, heat, vibration, etc. The housing of the battery pack also includes a battery management system (BMS), a thermal management system, an electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (supports), and protective components, forming a complete functional unit that can directly output electrical energy.

[0043] In embodiments of the present invention, the "casing" is a closed or semi-closed structure made of materials such as metal and plastic. Its design and manufacture must meet the safety, reliability, and functionality requirements of the battery pack under different usage scenarios. The casing provides installation space for battery modules, BMS, thermal management system, electrical connection system, structural components, and protective parts, and fixes these components inside the casing through reasonable structural design, ensuring that they maintain a relatively stable position during battery pack operation and avoiding damage to components or loosening of connections due to vibration, impact, or other factors.

[0044] Specifically, the casing generally consists of an upper casing and a lower casing. The lower casing is the main load-bearing component. The upper casing is connected to the lower casing, and the upper and lower casings together enclose the installation space.

[0045] The following is combined Figures 1 to 7 The following describes embodiments of the present invention.

[0046] According to embodiments of the present invention, in one aspect, such as Figure 1 and Figure 2 As shown, a battery pack housing is provided, including: a housing body 1, a thermal protection layer 2 attached to the inner surface of the housing body 1 opposite to the battery cell 4, the housing body 1 being made of composite material, the thickness of the housing body 1 being T1, the thickness of the thermal protection layer 2 being T2, satisfying 0.9≤T2 / T1≤2.

[0047] Therefore, the battery pack casing provided in this embodiment of the invention has a casing body 1 made of composite material, resulting in a lighter overall weight and facilitating lightweight design. A thermal protection layer 2 is attached to the inner surface of the casing body 1 in the area opposite to the battery cell 4. By controlling the ratio of the thickness of the thermal protection layer 2 to the thickness of the casing body 1 within a suitable range, the thermal protection capability and structural strength of the battery pack can be improved, thereby enhancing the pressure resistance of the casing body 1 during thermal runaway and providing better safety performance. If the value of T2 / T1 is too small, the casing body 1 is easily burned through during thermal runaway. If the value of T2 / T1 is too large, the casing body 1 is thicker, occupies more space, and has higher usage costs.

[0048] It should be noted that, in this embodiment of the invention, the thickness T1 of the shell body 1 and the thickness T2 of the heat protection layer 2 are both average thicknesses, and the average value can be taken after measuring the thickness at multiple locations.

[0049] In one embodiment, 1 mm ≤ T1 ≤ 1.5 mm, and 0.8 mm ≤ T2 ≤ 2 mm. By controlling the thickness of the casing 1 within a suitable range, a significant increase in the total weight and material cost of the battery pack due to excessive thickness of the casing 1 can be effectively avoided. This thickness range ensures that the casing 1 has sufficient mechanical strength and rigidity to withstand mechanical impacts, vibrations, and stresses generated by the expansion of the internal battery cells 4 during installation and use, providing reliable structural protection for the internal battery cells 4 and preventing safety hazards such as short circuits caused by deformation of the casing 1. If the value of T1 is too large, the cost of use will be high; if the value of T1 is too small, the structural strength of the casing 1 will be low.

[0050] By controlling the thickness of the shell body 1 within a suitable range, the structural strength of the shell body 1 can be further improved, while providing thermal protection capabilities. If the value of T2 is too large, the cost of use will be high; if the value of T2 is too small, the thermal protection layer 2 will be too thin, resulting in weak thermal protection performance.

[0051] In one embodiment, such as Figure 1 and Figure 2 As shown, a conductive layer 3 is provided on the inner surface of the shell body 1 in the area corresponding to the BMS (Battery Management System). The conductive layer 3 covers the surface of the BMS, and the thickness of the conductive layer 3 is T3, which satisfies 8≤T1 / T3≤13 and 0.12 mm≤T3≤0.18 mm. Similarly, the thickness T3 of the conductive layer 3 is also the average thickness.

[0052] A conductive layer 3 is provided on the inner surface of the casing 1 in the area corresponding to the BMS. This layer enhances the battery pack's electromagnetic interference resistance and electrical safety, preventing the BMS from malfunctioning due to electromagnetic interference, such as sudden high voltage or high current surges, which could lead to safety hazards. If the value of T1 / T3 is too small, the electromagnetic interference resistance is poor; if the value of T1 / T3 is too large, the conductive layer 3 becomes too thick, occupying a large amount of space and wasting material.

[0053] In one embodiment, such as Figure 2 and Figure 3 As shown, the shell body 1 includes a base plate 101 and side plates 102 surrounding the base plate 101. The base plate 101 and side plates 102 form a receiving space, which can accommodate at least the explosion-proof valve 401 of the battery cell 4. The thermal protection layer 2 is disposed on the inner surface of the base plate 101 and is disposed opposite to the explosion-proof valve 401. In the event of thermal runaway, a large amount of hot fluid will be ejected from the explosion-proof valve 401. The thermal protection layer 2 being disposed opposite to the explosion-proof valve 401 can effectively prevent the shell body 1 from being burned through in the event of thermal runaway.

[0054] In one embodiment, such as Figure 2 and Figure 7As shown, the width of the thermal protection layer 2 along the Y direction is W1, and the width of the battery cell 4 along the Y direction is W2, satisfying 0.08≤W2 / W1≤0.12 and 200 mm≤W1≤250 mm. By controlling W2 / W1 within a suitable range, it can be ensured that the thermal protection layer 2 fully covers the high-temperature fluid ejected from the explosion-proof valve 401 in the event of thermal runaway, thereby effectively isolating thermal shock, protecting the integrity of the base plate 101, preventing the base plate 101 from cracking due to high temperature, and significantly improving the safety performance of the battery pack.

[0055] In one embodiment, such as Figure 7 As shown, the length of cell 4 along the X direction is L1, and the width of explosion-proof valve 401 along the X direction is W3, satisfying 0.1≤W3 / L1≤0.13, 180 mm≤L1≤300 mm, and 23 mm≤W3≤28 mm. By controlling W3 / L1 within a suitable range, the explosion-proof valve 401 can release high pressure in time during thermal runaway, effectively suppressing the risk of cracking of the casing 1 and improving the reliability of the battery pack.

[0056] In one embodiment, such as Figures 3 to 6 As shown, the side plate 102 is folded along the XY plane to form a flange 103. A transition arc segment 104 is provided between the side plate 102 and the flange 103. The thickness of the flange 103 is T4. The radius of the outer rounded corner of the transition arc segment 104 is R1, and the radius of the inner rounded corner of the transition arc segment 104 is R2, satisfying R2=R1+T4. The flange 103 around the side plate 102 and the transition arc segment 104 between them effectively improve the structural strength of the shell body 1 and prevent the bottom plate 101 from cracking under stress. Since R2=R1+T4, the inner and outer contours of the transition arc segment 104 form a thickened arc, which facilitates the smooth transfer and dispersion of structural stress and reduces stress concentration.

[0057] Specifically, the XY plane is the plane formed by the X and Y directions, where the X direction is as follows: Figure 4 As shown by the arrow X in the diagram, the Y direction is as follows: Figure 4 As indicated by the arrow Y in the diagram.

[0058] Furthermore, in one embodiment, 3 mm ≤ T4 ≤ 4 mm, 5 mm ≤ R1 ≤ 8 mm, and 8 mm ≤ R2 ≤ 12 mm. By controlling T4 within a suitable range, it is possible to ensure that the flange 103 has sufficient structural strength, providing a reliable load-bearing foundation for the fastening connection between the upper and lower shells. By controlling R1 within a suitable range, it is possible to prevent the transition arc segment 104 from being too "blunt" and occupying too much internal or external space. By controlling R2 within a suitable range, the structural strength at the transition arc can be further enhanced.

[0059] For example, in the embodiments of the present invention, T4 can be 3 mm, 3.5 mm, 4 mm, etc., R1 can be 5 mm, 6 mm, 7 mm, 8 mm, etc., and R2 can be 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, etc.

[0060] In one embodiment, such as Figure 5 and Figure 6 As shown, a first transition fillet 105 is provided between the side plate 102 and the bottom plate 101. The radius of the first transition fillet 105 is R3. Along the X direction, the bottom plate 101 is provided with a plurality of reinforcing ribs 106 protruding in the Z direction at intervals. A second transition fillet 107 is provided between the reinforcing ribs 106 and the bottom plate 101. The radius of the second transition fillet 107 is R4, satisfying R3 / R4≥2.

[0061] Multiple reinforcing ribs 106 are spaced apart on the base plate 101 to enhance its structural strength and prevent it from tearing under excessive pressure during thermal runaway. A first transition fillet 105 is provided between the side plate 102 and the base plate 101 to withstand impacts, vibrations, and pressure from the internal battery cell 4, preventing stress concentration at the connection between the side plate 102 and the base plate 101. A second transition fillet 107 is provided between the reinforcing ribs 106 and the base plate 101 to prevent stress concentration at the connection between the reinforcing ribs 106 and the base plate 101. By controlling R3 / R4≥2, smooth stress transmission is ensured, further reducing the risk of cracking of the base plate 101.

[0062] It should be noted that the embodiments of the present invention do not limit the specific shape of the shell body 1.

[0063] For example, such as Figure 4 As shown, the middle area of ​​the base plate 101 along the Y direction protrudes in the Z direction. The protruding part is used to accommodate the wire harness. The two opposite sides of the base plate 101 along the Y direction respectively cover the explosion-proof valve 401 of the battery cell 4. The heat protection layer 2 is attached to the two sides, and multiple reinforcing ribs 106 are arranged at intervals.

[0064] Furthermore, in one embodiment, 20 mm ≤ R3 ≤ 22 mm, and 10 mm ≤ R4 ≤ 13 mm. By controlling R3 within a suitable range, the maximum stress concentration factor at the connection between the side plate 102 and the bottom plate 101 can be significantly reduced. By controlling R4 within a suitable range, it is ensured that the stiffener 106 can exist in a steeper and more effective "deep rib" form, thereby providing maximum bending stiffness within a limited arrangement space.

[0065] For example, in an embodiment of the present invention, R3 can be 21 mm and R4 can be 10.4 mm, then R3 / R4 is 2.019, or R3 can be 22 mm and R4 can be 10.5 mm, then R3 / R4 is 2.095, etc.

[0066] In one embodiment, such as Figure 6 As shown, the height of the reinforcing rib 106 along the Z direction is T5, which satisfies 1.5≤T5 / T2≤2.5 and 2 mm≤T5≤3 mm. By controlling T5 / T2 within a suitable range, it is possible to meet the requirements of lightweight battery pack while taking into account thermal protection performance and structural rigidity requirements, effectively enhancing the deformation resistance of the shell body 1.

[0067] It should be noted that the embodiments of the present invention do not limit the specific preparation process and materials of the composite material of the shell body 1, and any existing method can be selected as needed.

[0068] For example, the shell body 1 can be formed by composite processes such as PCM (prepreg molding), RTM (resin transfer molding), and STM (structural transfer molding). For instance, the shell body 1 uses PCM and the material is carbon fiber epoxy resin prepreg. RTM is used to combine carbon fiber braid and epoxy resin into carbon fiber epoxy resin, or glass fiber and polyurethane resin are combined into glass fiber polyurethane.

[0069] Furthermore, there are no restrictions on the materials used for the heat protection layer 2 and the conductive layer 3. For example, the heat protection layer 2 can be made of conventional heat protection materials such as mica or ceramics. The conductive layer 3 can be made of conductive cloth.

[0070] The following detailed description of the process parameters of the battery pack casing of the present invention, in conjunction with specific embodiments, is provided. These examples should not be construed as limiting the scope of protection claimed by the present invention.

[0071] Example 1:

[0072] The thickness T1 of the casing 1 is 1.2 mm, and the thickness T2 of the thermal protection layer 2 is 2 mm, so T2 / T1 is 1.67. The battery pack casing underwent pressure resistance testing, modal testing, and thermal runaway testing; the test results are shown in Table 1.

[0073] Example 2:

[0074] The thickness T1 of the casing 1 is 1.4 mm, and the thickness T2 of the thermal protection layer 2 is 1.5 mm, so T2 / T1 is 1.07. The battery pack casing underwent pressure resistance testing, modal testing, and thermal runaway testing; the test results are shown in Table 1.

[0075] Example 3:

[0076] The thickness T1 of the casing 1 is 1.5 mm, and the thickness T2 of the thermal protection layer 2 is 1.6 mm, so T2 / T1 is 1.07. The battery pack casing underwent pressure resistance testing, modal testing, and thermal runaway testing; the test results are shown in Table 1.

[0077] Comparative Example 1:

[0078] The thickness T1 of the casing 1 is 1.2 mm, and the thickness T2 of the thermal protection layer 2 is 0.8 mm. Therefore, T2 / T1 is 0.67, which is less than 0.9. The battery pack casing underwent pressure resistance testing, modal testing, and thermal runaway testing. The test results are shown in Table 1.

[0079] Comparative Example 2:

[0080] The thickness T1 of the casing 1 is 1 mm, and the thickness T2 of the thermal protection layer 2 is 0.8 mm. Therefore, T2 / T1 is 0.8, which is less than 0.9. The battery pack casing underwent pressure resistance testing, modal testing, and thermal runaway testing. The test results are shown in Table 1.

[0081] Comparative Example 3:

[0082] The thickness T1 of the casing 1 is 0.8 mm, which is less than 1 mm, and the thickness T2 of the thermal protection layer 2 is 0.8 mm, so T2 / T1 is 1. The battery pack casing underwent pressure resistance testing, modal testing, and thermal runaway testing. The test results are shown in Table 1.

[0083] Comparative Example 4:

[0084] The thickness T1 of the casing 1 is 1.3 mm, and the thickness T2 of the thermal protection layer 2 is 2.5 mm, which is greater than 2 mm. Therefore, T2 / T1 is 1.92. The battery pack casing underwent withstand voltage testing, modal testing, and thermal runaway testing. The test results are shown in Table 1.

[0085] Table 1: Test Results

[0086]

[0087] As shown in Table 1, in Examples 1 to 3, the following conditions are met: 1 mm ≤ T1 ≤ 1.5 mm, 0.8 mm ≤ T2 ≤ 2 mm, and 0.9 ≤ T2 / T1 ≤ 2. The battery pack upper casing can pass the pressure resistance test, modal test, and thermal runaway test, demonstrating good structural strength and thermal protection performance.

[0088] In Comparative Examples 1 and 2, T2 / T1 was less than 0.9, in Comparative Example 3 T1 was less than 1 mm, and in Comparative Example 4 T2 was greater than 2 mm. All of them failed the pressure resistance test, modal test, and thermal runaway test.

[0089] It should be noted that the pressure resistance test conditions mentioned above are above 20 kPa, referring to standard GB / T 4208-2017. The modal test conditions are above 35 Hz, referring to standard GB / T 31467.3-2015, and the thermal runaway test refers to standard GB38031-2020.

[0090] Example 4:

[0091] The thickness T1 of the casing 1 is 1 mm, and the thickness T3 of the conductive layer 3 is 0.12 mm, so T1 / T3 is 8.33. EMC testing was performed on the battery pack casing, and the results are shown in Table 2.

[0092] Example 5:

[0093] The thickness T1 of the casing 1 is 1.2 mm, and the thickness T3 of the conductive layer 3 is 0.15 mm, so T1 / T3 is 8. EMC testing was performed on the battery pack casing, and the results are shown in Table 2.

[0094] Example 6:

[0095] The thickness T1 of the casing 1 is 1.5 mm, and the thickness T3 of the conductive layer 3 is 0.12 mm, so T1 / T3 is 12.5. EMC testing was performed on the battery pack casing, and the results are shown in Table 2.

[0096] Example 7:

[0097] The thickness T1 of the casing 1 is 1.5 mm, and the thickness T3 of the conductive layer 3 is 0.17 mm, so T1 / T3 is 8.82. EMC testing was performed on the battery pack casing, and the results are shown in Table 2.

[0098] Example 8:

[0099] The thickness T1 of the casing 1 is 1.4 mm, and the thickness T3 of the conductive layer 3 is 0.16 mm, so T1 / T3 is 8.75. EMC testing was performed on the battery pack casing, and the results are shown in Table 2.

[0100] Comparative Example 5:

[0101] The thickness T1 of the casing 1 is 1.2 mm, and the thickness T3 of the conductive layer 3 is 0.18 mm. Therefore, T1 / T3 is 6.67, which is less than 8. EMC testing was performed on the battery pack casing, and the test results are shown in Table 2.

[0102] Comparative Example 6:

[0103] The thickness T1 of the casing 1 is 0.9 mm, and the thickness T3 of the conductive layer 3 is 0.18 mm. Therefore, T1 / T3 is 5, which is less than 8. EMC testing was performed on the battery pack casing, and the test results are shown in Table 2.

[0104] Table 2: Test Results

[0105]

[0106] As shown in Table 2, in Examples 4 to 8, the following conditions are met: 1 mm ≤ T1 ≤ 1.5 mm, 0.12 mm ≤ T3 ≤ 0.18 mm, and 8 ≤ T1 / T3 ≤ 13. The battery pack casing can pass the EMC test (electromagnetic interference test) and has good electromagnetic interference resistance.

[0107] In Comparative Examples 5 and 6, T1 / T3 was less than 8, and both failed the EMC test, indicating poor electromagnetic interference resistance.

[0108] It should be noted that the above EMC test reference standard is GB / T 18655-2018.

[0109] Example 9:

[0110] The radius R1 of the outer rounded corner of transition arc segment 104 is 5 mm, the thickness T4 of flange 103 is 3 mm, and the radius R2 of the inner rounded corner of transition arc segment 104 is 8 mm. The radius R3 of the first transition rounded corner 105 is 20 mm, and the radius R4 of the second transition rounded corner 107 is 10 mm, so R3 / R4 = 2. Production line testing and verification were performed on the battery pack casing, and the results are shown in Table 3.

[0111] Comparative Example 7:

[0112] The radius R1 of the outer rounded corner of transition segment 104 is 4 mm, which is less than 5 mm. The thickness T4 of the flange 103 is 3 mm. The radius R2 of the inner rounded corner of transition segment 104 is 7 mm, which is less than 8 mm. The radius R3 of the first transition rounded corner 105 is 22 mm, and the radius R4 of the second transition rounded corner 107 is 15 mm. Therefore, R3 / R4 = 1.467, which is less than 2. The battery pack casing was tested and verified on the production line. The results are shown in Table 3.

[0113] Comparative Example 8:

[0114] The radius R1 of the outer rounded corner of transition arc segment 104 is 6 mm, the thickness T4 of flange 103 is 2 mm, which is less than 3 mm, and the radius R2 of the inner rounded corner of transition arc segment 104 is 8 mm. The radius R3 of the first transition rounded corner 105 is 25 mm, and the radius R4 of the second transition rounded corner 107 is 18 mm. Therefore, R3 / R4 = 1.389, which is less than 2. The battery pack upper casing was tested and verified on the production line, and the results are shown in Table 3.

[0115] Comparative Example 9:

[0116] The radius R1 of the outer rounded corner of transition arc segment 104 is 6 mm, the thickness T4 of flange 103 is 4 mm, and the radius R2 of the inner rounded corner of transition arc segment 104 is 10 mm. The radius R3 of the first transition rounded corner 105 is 15 mm, which is less than 20 mm, and the radius R4 of the second transition rounded corner 107 is 8 mm, which is less than 10 mm. Therefore, R3 / R4 = 1.875, which is less than 2. The battery pack casing was tested and verified on the production line, and the results are shown in Table 3.

[0117] Comparative Example 10:

[0118] The radius R1 of the outer rounded corner of transition arc segment 104 is 7 mm, the thickness T4 of flange 103 is 2 mm (less than 3 mm), and the radius R2 of the inner rounded corner of transition arc segment 104 is 9 mm. The radius R3 of the first transition rounded corner 105 is 25 mm, and the radius R4 of the second transition rounded corner 107 is 12 mm, therefore R3 / R4 = 2.083. Production line testing and verification were performed on the battery pack casing; the results are shown in Table 3.

[0119] Table 3: Test Results

[0120]

[0121] As shown in Table 3, in Example 9, the following conditions are met: 3 mm ≤ T4 ≤ 4 mm, 5 mm ≤ R1 ≤ 8 mm, 8 mm ≤ R2 ≤ 12 mm, 20 mm ≤ R3 ≤ 22 mm, 10 mm ≤ R4 ≤ 13 mm, and R3 / R4 ≥ 2. The battery pack casing can pass the production line test and verification, and has good structural strength.

[0122] In Comparative Example 7, R1 is less than 5 mm, R2 is less than 8 mm, and R3 / R4 is less than 2. Tests revealed cracking defects on the large surface of the shell body 1 and at the flange 103.

[0123] In Comparative Example 8, T4 is less than 3 mm and R3 / R4 is less than 2. Tests revealed cracking defects on the large surface of the shell body 1 and at the flange 103.

[0124] In Comparative Example 9, R3 is less than 20 mm, R4 is less than 10 mm, and R3 / R4 is less than 2. The test revealed that the large surface of the shell body 1 had a crack defect.

[0125] In Comparative Example 10, T4 was less than 3 mm, and a crack defect was found at the flange 103 during testing.

[0126] Example 10:

[0127] The width W1 of the thermal protection layer 2 along the Y direction is 210 mm, and the width W2 of the cell 4 along the Y direction is 25 mm, so W2 / W1 is 0.119. Thermal runaway testing was performed on the battery pack casing to verify the results, which are shown in Table 4.

[0128] Example 11:

[0129] The width W1 of the thermal protection layer 2 along the Y direction is 220 mm, and the width W2 of the cell 4 along the Y direction is 26 mm, so W2 / W1 is 0.118. Thermal runaway testing was performed on the battery pack casing to verify the results, which are shown in Table 4.

[0130] Example 12:

[0131] The width W1 of the thermal protection layer 2 along the Y direction is 225 mm, and the width W2 of the cell 4 along the Y direction is 26 mm, so W2 / W1 is 0.116. Thermal runaway testing was performed on the battery pack casing to verify the results, which are shown in Table 4.

[0132] Example 13:

[0133] The width W1 of the thermal protection layer 2 along the Y direction is 215 mm, and the width W2 of the cell 4 along the Y direction is 25 mm, so W2 / W1 is 0.116. Thermal runaway testing was performed on the battery pack casing to verify the results, which are shown in Table 4.

[0134] Example 14:

[0135] The width W1 of the thermal protection layer 2 along the Y direction is 230 mm, and the width W2 of the cell 4 along the Y direction is 27 mm, so W2 / W1 is 0.117. Thermal runaway testing was performed on the battery pack casing to verify the results, which are shown in Table 4.

[0136] Comparative Example 11:

[0137] The width W1 of the thermal protection layer 2 along the Y direction is 280 mm, which is greater than 250 mm. The width W2 of the cell 4 along the Y direction is 27 mm, so W2 / W1 is 0.096. Thermal runaway tests were performed on the battery pack casing to verify the results, which are shown in Table 4.

[0138] Comparative Example 12:

[0139] The width W1 of the thermal protection layer 2 along the Y direction is 180 mm, and the width W2 of the cell 4 along the Y direction is 25 mm. Therefore, W2 / W1 is 0.139, which is greater than 0.12. Thermal runaway tests were performed on the battery pack casing to verify the results, which are shown in Table 4.

[0140] Table 4: Test Results

[0141]

[0142] As shown in Table 4, in Examples 10 to 14, the following conditions are met: 0.08 ≤ W2 / W1 ≤ 0.12, 200 mm ≤ W1 ≤ 250 mm. The battery pack casing can pass the thermal runaway test and has good structural strength and thermal protection performance.

[0143] In Comparative Example 11, W1 was greater than 250 mm, and the test revealed that the shell body 1 was cracked.

[0144] In Comparative Example 12, W2 / W1 was greater than 0.12, and the test revealed that the shell body 1 was cracked.

[0145] Example 15:

[0146] The height T5 of the reinforcing rib 106 along the Z direction is 2 mm, and the thickness T2 of the thermal protection layer 2 is 0.9 mm, so T5 / T2 is 2.22. Thermal runaway testing was performed on the battery pack upper casing to verify the results, which are shown in Table 5.

[0147] Example 16:

[0148] The height T5 of the reinforcing rib 106 along the Z direction is 2.8 mm, and the thickness T2 of the thermal protection layer 2 is 1.5 mm, so T5 / T2 is 1.87. Thermal runaway testing was performed on the battery pack casing; the test results are shown in Table 5.

[0149] Comparative Example 13:

[0150] The height T5 of the reinforcing rib 106 along the Z direction is 2.9 mm, and the thickness T2 of the thermal protection layer 2 is 1.95 mm. Therefore, T5 / T2 is 1.49, which is less than 1.5. Thermal runaway tests were performed on the battery pack casing to verify the results, which are shown in Table 5.

[0151] Comparative Example 14:

[0152] The height T5 of the reinforcing rib 106 along the Z direction is 2.2 mm, and the thickness T2 of the thermal protection layer 2 is 1.9 mm. Therefore, T5 / T2 is 1.16, which is less than 1.5. Thermal runaway tests were performed on the battery pack casing to verify the results, which are shown in Table 5.

[0153] Comparative Example 15:

[0154] The height T5 of the reinforcing rib 106 along the Z direction is 2.5 mm, and the thickness T2 of the thermal protection layer 2 is 0.9 mm, so T5 / T2 is 2.78. Thermal runaway testing was performed on the battery pack casing; the test results are shown in Table 5.

[0155] Table 5: Test Results

[0156]

[0157] As shown in Table 5, in Examples 15 and 16, the following conditions are met: 1.5 ≤ T5 / T2 ≤ 2.5, and 2 mm ≤ T5 ≤ 3 mm. The battery pack casing can pass the thermal runaway test and has good structural strength and thermal protection performance.

[0158] In Comparative Examples 13 and 14, T5 / T2 was less than 1.5, failing the thermal runaway test and indicating poor thermal protection.

[0159] In Comparative Example 15, T5 / T2 was greater than 2.5, failing the thermal runaway test and indicating poor thermal protection.

[0160] According to an embodiment of the present invention, in another aspect, a battery pack is also provided, comprising: an upper housing, a lower housing, and at least one battery cell 4, wherein the lower housing is connected to the upper housing and forms a closed mounting space. The battery cell 4 is mounted within the mounting space, and the explosion-proof valve 401 of the battery cell 4 faces the inner surface of the upper housing and is disposed opposite to the heat protection layer 2.

[0161] The battery pack provided in this embodiment of the invention has a casing 1 made of composite material, which is lightweight and facilitates lightweight design. A thermal protection layer 2 is attached to the inner surface of the casing 1 in the area opposite to the battery cell 4. By controlling the ratio of the thickness of the thermal protection layer 2 to the thickness of the casing 1 within a suitable range, the thermal protection capability and structural strength of the battery pack can be improved, thereby enhancing the pressure resistance of the casing 1 in the event of thermal runaway and providing better safety performance. If the value of T2 / T1 is too small, the casing 1 is easily burned through in the event of thermal runaway. If the value of T2 / T1 is too large, the casing 1 is thicker, occupies more space, and has higher operating costs. Moreover, the explosion-proof valve 401 faces the inner surface of the casing 1 and is positioned opposite to the thermal protection layer 2, which can effectively prevent the casing 1 from being burned through in the event of thermal runaway.

[0162] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A battery pack housing, characterized in that, include: The shell body has a thermal protection layer attached to the inner surface of the shell body in the area opposite to the battery cell. The shell body is made of composite material. The thickness of the shell body is T1, and the thickness of the thermal protection layer is T2, satisfying 0.9≤T2 / T1≤2, 1 mm≤T1≤1.5 mm, and 0.8 mm≤T2≤2 mm. The inner surface of the shell body is provided with a conductive layer in the area corresponding to the BMS. The conductive layer covers the surface of the BMS. The thickness of the conductive layer is T3, which satisfies 8≤T1 / T3≤13 and 0.12 mm≤T3≤0.18 mm. The shell body includes a bottom plate and side plates surrounding the bottom plate. The bottom plate and the side plates form an accommodating space, which at least accommodates the explosion-proof valve of the battery cell. The thermal protection layer is disposed on the inner surface of the bottom plate and is disposed opposite to the explosion-proof valve. The width of the thermal protection layer along the Y direction is W1, and the width of the battery cell along the Y direction is W2, satisfying 0.08≤W2 / W1≤0.12, 200 mm≤W1≤250 mm; The length of the battery cell along the X direction is L1, and the width of the explosion-proof valve along the X direction is W3, satisfying 0.1≤W3 / L1≤0.13, 180 mm≤L1≤300 mm, and 23 mm≤W3≤28 mm.

2. The battery pack housing according to claim 1, characterized in that, The side plate is folded along the XY plane to form a flange. A transition arc is provided between the side plate and the flange. The thickness of the flange is T4. The radius of the outer rounded corner of the transition arc is R1, and the radius of the inner rounded corner of the transition arc is R2, satisfying R2=R1+T4, 3 mm≤T4≤4mm, 5 mm≤R1≤8 mm, and 8 mm≤R2≤12 mm.

3. The battery pack housing according to claim 1, characterized in that, A first transition fillet is provided between the side plate and the bottom plate, the radius of the first transition fillet is R3 along the X direction, the bottom plate is provided with a plurality of reinforcing ribs protruding in the Z direction at intervals, and a second transition fillet is provided between the reinforcing ribs and the bottom plate, the radius of the second transition fillet is R4, satisfying R3 / R4≥2, 20 mm≤R3≤22 mm, 10 mm≤R4≤13 mm.

4. The battery pack housing according to claim 3, characterized in that, The height of the reinforcing rib along the Z direction is T5, which satisfies 1.5≤T5 / T2≤2.5 and 2 mm≤T5≤3 mm.

5. A battery pack, characterized in that, include: Battery pack housing according to any one of claims 1 to 4; The lower housing connects to the upper housing of the battery pack to form a closed installation space; At least one battery cell is installed in the installation space, with the explosion-proof valve of the battery cell facing the inner surface of the upper housing and disposed opposite to the thermal protection layer.

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