A battery pack

Abstract

This invention provides a battery pack with superior adhesive strength, thereby improving its safety performance. The battery pack includes: a housing; battery units housed within the housing, each battery unit comprising a plurality of batteries, including a first battery and a second battery, the first and second batteries being alternately arranged; each of the first and second batteries includes a casing and an insulating film covering the outer surface of the casing, and the insulating film covering the casing of the second battery has perforated areas on its bottom and lower sides corresponding to the second battery; structural adhesive for fixing the first and second batteries to the housing; and a first limiting strip may or may not be provided between the bottom surface of each battery and the housing.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more particularly to a battery pack. Background Technology

[0002] Currently, many power battery packs integrate the batteries directly into the housing to improve assembly efficiency and reduce costs, which is the CTP (Cell to Pack) structure. This simplifies the original battery module design, thereby reducing the number of parts, improving integration efficiency and energy density, and reducing costs.

[0003] In CTP battery packs, the batteries are typically fixed to the casing using adhesive. The battery casing is usually made of metal (such as aluminum). Due to the high insulation requirements of the batteries, insulating films are usually wrapped around the sides and bottom of the batteries. However, the adhesion strength between the insulating film and the structural adhesive is relatively weak, and the battery pack is prone to adhesive failure during long-term use, leading to safety issues. Some CTP battery packs add pressure strips above the batteries to increase the structural strength of the battery pack. This approach increases the complexity of the CTP structure, reduces assembly efficiency, and increases the cost of the battery pack, while offering limited improvement in structural strength. Summary of the Invention

[0004] To address at least one deficiency in the existing technology, the present invention provides a battery pack with better adhesive strength, thereby improving the safety performance of the battery pack.

[0005] To achieve its objective, the present invention provides the following technical solution:

[0006] This invention provides a battery pack, comprising:

[0007] Box;

[0008] A battery unit is housed in the housing. The battery unit includes multiple batteries, including a first battery and a second battery, which are arranged alternately. The first battery and the second battery each include a housing and an insulating film covering the outer surface of the housing. The insulating film covering the housing of the second battery has a cutout area on the bottom and lower side of the second battery, so that the area of ​​the housing of the second battery corresponding to the cutout area is exposed to the insulating film.

[0009] Structural adhesive is disposed between the bottom surface of the first battery, the bottom surface of the second battery, and the housing, and covers the hollow area of ​​the second battery, for fixing the first battery and the second battery to the housing;

[0010] A first limiting strip may or may not be provided between the bottom surface of each battery and the housing;

[0011] (1) When the number of the first battery and the number of the second battery in the battery cell are equal, the following relationship is satisfied:

[0012]

[0013] (2) When the number of the first batteries in the battery cell is K and the number of the second batteries is K+1, where K≥1, the following relationship is satisfied:

[0014]

[0015] (3) When the number of the first batteries in the battery cell is K+1 and the number of the second batteries is K, where K≥1, the following relationship is satisfied:

[0016]

[0017] In the above formula, σ1 is the bonding strength of the insulating film to the box body through the structural adhesive, σ2 is the bonding strength of the shell to the box body through the structural adhesive, S is the bottom area of ​​a single battery, S1 is the contact area between a single first limiting strip and the bottom surface of a single battery, and n1 is the number of first limiting strips corresponding to the bottom surface of a single battery.

[0018] In some embodiments, there are multiple battery cells arranged side by side; between two adjacent rows of battery cells, the first battery and the second battery are arranged alternately.

[0019] Preferably, adjacent rows of battery cells are connected by a second buffer pad.

[0020] Preferably, the second buffer pad connects two adjacent rows of battery cells into one unit by means of adhesive bonding.

[0021] Preferably, in the battery cell, adjacent first batteries and second batteries are connected by a first buffer pad.

[0022] Preferably, a support structure is provided on the outside of the battery cell to keep the first buffer pad in a compressed state;

[0023] And / or, the first buffer pad connects the first battery and the second battery in the battery cell into one unit by means of adhesive bonding.

[0024] Preferably, the surface of the housing corresponding to the bottom surface of the first battery and the bottom surface of the second battery is provided with an insulating coating.

[0025] Preferably, inside the housing, a second limiting strip is provided on the outside of the battery cell located on the outer side to limit the overflow height of the structural adhesive, and to allow the structural adhesive to cover the hollow area.

[0026] Furthermore, the rounded corner area on the lower side of the second battery is located within the hollowed-out area.

[0027] In some examples, 0 ≤ n1S1 / S×100% ≤ 30%;

[0028] And / or, 0 MPa < σ1 < 3 MPa, σ2 ≥ 6 MPa.

[0029] And / or, the material of the structural adhesive is selected from one or more of polyurethane and epoxy resin;

[0030] And / or, the thickness of the first buffer pad is 0.5-1.5 mm;

[0031] And / or, the thickness of the second cushioning pad is 0.5-5mm;

[0032] And / or, the thickness of the insulating film is 0.015-0.2 mm.

[0033] The technical solution provided by this invention has the following beneficial effects:

[0034] In the battery pack of the present invention, a first battery without a hollow area and a second battery with a hollow area are mixed and assembled. By reasonably setting the relevant parameters in the above-mentioned formulas, the corresponding calculation results are made to be ≥4MPa, which can improve the safety performance of the battery pack, improve the structural strength of the battery pack, and at the same time greatly reduce the design cost and improve the development efficiency. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the first battery in one embodiment;

[0036] Figure 2 This is a schematic diagram of the second battery in one embodiment;

[0037] Figure 3 This is a schematic diagram of a battery pack in one embodiment;

[0038] Figure 4 A side view of two rows of battery sub-units arranged side by side;

[0039] Figure 5 for Figure 4 A schematic diagram of the bottom of the battery cell.

[0040] Reference numerals: Battery unit 100, first battery 1, second battery 2, casing 3, insulating film 4, lower side 5, bottom surface 6, side 7, box body 8, first buffer pad 9, end plate 10, beam 11, structural adhesive 12, first limiting strip 13, second limiting strip 14, hollow area 15, second buffer pad 16, insulating coating 17. Detailed Implementation

[0041] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0043] The directional terms such as up, down, left, right, front, back, front, back, top, and bottom mentioned or possibly used in this specification are defined relative to the construction shown in the accompanying drawings. These are relative concepts and may therefore vary depending on their location and usage. The terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] See Figure 1-5 The battery pack provided by the present invention includes a housing 8, a battery unit 100, and structural adhesive 12.

[0045] The battery unit 100 is housed within the casing 8. (See also...) Figure 3Each battery cell 100 includes multiple batteries, including a first battery 1 and a second battery 2. In each battery cell 100, the first battery 1 and the second battery 2 are arranged alternately to form a row of batteries. The first battery 1 includes a housing 3 and an insulating film 4 covering the outer surface of the housing 3. Similarly, the second battery 2 also includes a housing 3 and an insulating film 4 covering the outer surface of the housing 3. The difference between the second battery 2 and the first battery 1 is that the insulating film 4 of the second battery 2 has perforated areas 15. Specifically, the insulating film 4 has perforated areas 15 corresponding to the bottom surface 6 and the lower side surface 5 of the second battery 2, so that the housing 3 of the second battery 2 corresponding to the position of the perforated areas 15 is exposed to the insulating film 4, and the surface of the housing 3 of the second battery 2 in these areas is not covered by the insulating film 4; the insulating film 4 of the first battery 1 does not have such perforated areas 15, that is, the bottom surface 6 and the side surface 7 of the first battery 1 are completely covered by the insulating film 4. Structural adhesive 12 is provided between the bottom surface 6 of the first battery 1, the bottom surface 6 of the second battery 2, and the housing 8. Specifically, structural adhesive 12 is provided between the bottom surface 6 of the first battery 1 and the housing 8, and between the bottom surface 6 of the second battery 2 and the housing 8. The structural adhesive 12 covers the perforated area 15 of the insulating film 4 of the second battery 2, so that the exposed bottom surface 6 of the housing 3 and the lower side surface 5 of the housing 3 of the second battery 2 are covered by the structural adhesive 12. The structural adhesive 12 fixes the first battery 1 and the second battery 2 to the housing 8. Optionally, a first limiting strip 13 is provided between the bottom surface 6 of each battery and the housing 8; that is, the first limiting strip 13 may or may not be provided.

[0046] In the battery pack of the present invention, a first battery 1 without a hollow area 15 and a second battery 2 with a hollow area 15 are mixed and assembled to obtain good overall structural strength of the battery pack.

[0047] In the battery pack of the present invention, when the number of first battery 1 and second battery 2 in battery cell 100 is equal, the following relationship (1) is satisfied between σ1, σ2, S, S1, and n1. The battery pack has better bonding strength, the overall structural strength of the battery pack is improved, and it can meet the mechanical impact test requirements of GB / T 31467.3 7.2. It can resist mechanical impact and successfully pass the mechanical impact test.

[0048]

[0049] When the number of first batteries 1 in battery cell 100 is K and the number of second batteries 2 is K+1, where K≥1, the following relationship (2) is satisfied between σ1, σ2, S, S1, n1, and K. The battery pack has better bonding strength, the overall structural strength of the battery pack is improved, and it can meet the mechanical impact test requirements of GB / T 31467.3 7.2. It can resist mechanical impact and pass the mechanical impact test smoothly.

[0050]

[0051] When the number of first batteries 1 in battery cell 100 is K+1 and the number of second batteries 2 is K, where K≥1, the following relationship (3) is satisfied between σ1, σ2, S, S1, n1, and K. The battery pack has better bonding strength, the overall structural strength of the battery pack is improved, and it can meet the mechanical impact test requirements of GB / T 31467.3 7.2. It can resist mechanical impact and pass the mechanical impact test smoothly.

[0052]

[0053] In the above formula, the bonding strength of the insulating film 4 to the housing 8 via structural adhesive 12 is σ1, in MPa; the bonding strength of the shell 3 to the housing 8 via structural adhesive 12 is σ2, in MPa; the bottom area of ​​a single battery is S; the contact area between a single first limiting strip 13 and the bottom surface 6 of a single battery is S1; the number of first limiting strips 13 corresponding to the bottom surface 6 of a single battery is n1. When the bottom surface 6 of a single battery does not have a first limiting strip 13, n1 = 0.

[0054] In relation (1), let That is, let σ ≥ 4MPa. In relation (2), let That is, let σ ≥ 4 MPa. In relation (3), let That is, let σ≥4MPa. In the above relationships (1)-(3), the larger the calculated value of σ, the greater the bonding strength of the battery pack. In order to meet the better bonding strength requirements, the relevant parameters in the above relationships can be reasonably set to obtain the required calculated value of σ, such as at least σ≥4MPa or reaching a higher level, thereby improving the safety performance of the battery pack, while also greatly reducing the design cost and improving development efficiency.

[0055] Preferably, in the battery unit 100, a first buffer pad 9 is provided between adjacent batteries, and the first buffer pad 9 connects adjacent first batteries 1 and second batteries 2 into one unit. Specifically, the first buffer pad 9 is connected to adjacent first batteries 1 and second batteries 2 by adhesive bonding, so that each first battery 1 and second battery 2 in the battery unit 100 is alternately connected into one unit, which can improve the structural strength of the entire battery pack and enhance the safety of the battery pack.

[0056] The number of battery cells 100 can be one or more, such as Figure 4 , 5As shown, when multiple battery units 100 are provided, the multiple battery units 100 are arranged side by side, and the first battery 1 and the second battery 2 are arranged alternately between two adjacent rows of battery units 100. Specifically, the multiple battery units 100 arranged side by side include multiple rows and multiple columns of batteries, and the first battery 1 and the second battery 2 are arranged alternately between each row of batteries, each column of batteries, and between adjacent rows of batteries and adjacent columns of batteries.

[0057] Preferably, a second buffer pad 16 is provided between two adjacent rows of battery cells 100. The second buffer pad 16 connects the adjacent battery cells 100. Specifically, for example, the second buffer pad 16 is connected to the battery cells 100 on both sides by adhesive bonding, so that all battery cells 100 are integrated, which can improve the structural strength of the entire battery pack and enhance the safety of the battery pack. The second buffer pad 16 also serves as a heat insulation buffer, ensuring the gap between adjacent battery cells. Specifically, the height of the second buffer pad 16 from the bottom of the battery is not less than the height of the hollow area 15 of the insulating film 4 of the second battery 2, so that the structural adhesive 12 can cover the surface of the shell 3 corresponding to the hollow area 15.

[0058] Furthermore, in all battery cells 100, a support structure is provided on the outside of the battery cell 100 to keep the first buffer pad 9 in a compressed state. The support structure is, for example, an end plate 10 located on the outside of the battery cell 100. The end plate 10 may also have a beam 11 or other structure providing support for the battery pack. After the battery pack is assembled, the support structure provides support and insulation, and keeps the first buffer pad 9 between the first battery 1 and the second battery 2 of the battery cell 100 in a compressed state, possessing a certain amount of compression and rebound force, so that the two adjacent batteries form a whole. The first buffer pad 9 also provides heat insulation and buffering, and ensures the gap between two adjacent batteries. By binding the first battery 1 and the second battery 2 within the battery cell 100 together with the first buffer pad 9 and the second buffer pad 16, the first battery 1 with relatively weak adhesion and the second battery 2 with relatively strong adhesion can be regarded as a whole, greatly improving the structural strength after the batteries are stacked. The first battery 1 and the second battery 2 are mixed and alternately assembled, and the first buffer pad 9 and the second buffer pad 16 are used to connect the rows and columns of batteries into one unit. With or without the first limiting strip 13, the battery pack is designed by adapting the above three relationships and making σ≥4MPa. A battery pack with reliable bonding strength and good safety can be obtained. The implementation of the present invention is simple, requires few parts, and has low cost. It can greatly improve the integration efficiency and design efficiency of the battery pack and reduce costs.

[0059] In some embodiments, an insulating coating 17 is provided on the surface of the housing 8 corresponding to the bottom surface 6 of the first battery 1 and the bottom surface 6 of the second battery 2. That is, the surface of the housing 8 corresponding to the bottom surface 6 of the first battery 1 and the surface of the housing 8 corresponding to the bottom surface 6 of the second battery 2 are provided with an insulating coating 17. Providing an insulating coating 17 helps to enhance the insulation effect.

[0060] In some embodiments, within the housing 8, a second limiting strip 14 is provided on the outer side of the outermost battery cell 100 to limit the overflow height of the structural adhesive 12, and to allow the structural adhesive 12 to cover the hollowed-out area 15 of the second battery 2. Specifically, the structural adhesive 12 covers the surface of the housing 3 corresponding to the hollowed-out area 15. The height of the second limiting strip 14 limits the maximum thickness of the structural adhesive 12 on the side of the outermost battery of the battery cell 100. The length of the second limiting strip 14 can be specifically set to match the row or column of batteries corresponding to the position.

[0061] Furthermore, the rounded corner area 19 of the lower side surface 5 of the second battery 2 is located within the hollow area 15, that is, the rounded corner area 19 of the lower side surface 5 of the second battery 2 is not covered by the insulating film 4, and this area is covered by structural adhesive 12. Specifically, the lower side surface 5 is the side portion of the bottom surface 6 of the casing adjacent to the second battery.

[0062] In this invention, the specific materials of the insulating film 4, insulating coating 17, structural adhesive 12, etc., are not particularly limited, and can be corresponding materials applicable in the art. For example, the material of the insulating film 4 is, for example, but not limited to, polyester resin (PET), polycarbonate (PC), etc.; the material of the insulating coating 17 is, for example, but not limited to, epoxy powder; and the material of the structural adhesive 12 is, for example, but not limited to, one or more of polyurethane and epoxy resin. The materials of the first limiting strip 13 and the second limiting strip 14 can both be materials known in the art, for example, but not limited to, polycarbonate (PC) or other rigid plastics, foam, etc. The material of the first buffer pad 9 can be, for example, but not limited to, polypropylene foam (MPP), aerogel, etc., and the material of the second buffer pad 16 can be, for example, but not limited to, polypropylene foam (MPP), aerogel, epoxy board, etc. The material of the battery casing can be, for example, aluminum or steel, etc., and the material of the box can be, for example, aluminum or steel, etc.

[0063] Preferably, 0 MPa < σ1 < 3 MPa, σ2 ≥ 6 MPa; the thickness of the first buffer pad 9 is, for example, 0.5-1.5 mm; the thickness of the second buffer pad 16 is, for example, 0.5-5 mm; and the thickness of the insulating film 4 is, for example, 0.015-0.2 mm. The number of first limiting strips 13 between the bottom surface 6 of a single battery and the housing 8 is not particularly limited, for example, 0 strips, 1 strip, or multiple strips, such as 1-4 strips, for example, 1, 2, 3, 4 strips, etc. In some examples, the height of the first limiting strip 13 is, for example, 0.5-2.5 mm, and the thickness of the structural adhesive 12 is, for example, 0.5-2.5 mm.

[0064] In one test example of this application, structural adhesive A and structural adhesive B were used respectively. Figure 1-5 Experiments were conducted on the battery pack shown. Structural adhesives A and B were made of polyurethane structural adhesive, without an insulating coating. The battery casing and housing were made of aluminum, the first limiting strip was made of polycarbonate (PC), and the insulating film was made of polyester resin (PET). The parameters of the battery pack are shown in Table 1 below.

[0065] Table 1

[0066]

[0067]

[0068] This test case conducted a series of experiments:

[0069] (i) The number of first batteries 1 and second batteries 2 in the battery unit is the same. By changing the type of structural adhesive, and changing the contact area S1 between a single first limiting strip 13 and the bottom surface 6 of a single battery and / or the number n1 of first limiting strips 13 corresponding to the bottom surface 6 of a single battery, multiple sets of experiments were carried out under different n1S1 / S×100%. The σ calculation value corresponding to each set of experiments was calculated using the relation (1). The specific test results are shown in Table 2.

[0070] Table 2 (Relationship (1))

[0071]

[0072] (ii) The number of first batteries 1 in the battery unit is K = 31, and the number of second batteries 2 is K+1 = 32. By changing the type of structural adhesive, and changing the contact area S1 between a single first limiting strip 13 and the bottom surface 6 of a single battery and / or the number n1 of the first limiting strips 13 corresponding to the bottom surface 6 of a single battery, multiple sets of experiments were carried out under different n1S1 / S×100%. The σ calculation value corresponding to each set of experiments was calculated using the relation (2). The specific test results are shown in Table 3.

[0073] Table 3 (Relationship (2))

[0074]

[0075]

[0076] (III) The number of first batteries 1 in the battery unit is K+1=32, and the number of second batteries 2 is K=31. By changing the type of structural adhesive, and changing the contact area S1 between a single first limiting strip 13 and the bottom surface 6 of a single battery and / or the number n1 of the first limiting strips 13 corresponding to the bottom surface 6 of a single battery, multiple sets of experiments were carried out under different n1S1 / S×100%. The σ calculation value corresponding to each set of experiments was calculated using the relation (3). The specific test results are shown in Table 4.

[0077] Table 4 (Relationship (3))

[0078]

[0079] In Tables 2-4 above, the battery packs of each case were tested in accordance with GB / T 31467.3 7.2. If they can pass the mechanical impact test, the result is "OK"; otherwise, it is "NG".

[0080] As can be seen from the above experimental results, all battery packs whose calculated σ values ​​obtained by formulas (1)-(3) meet the requirement of ≥4MPa can pass the mechanical impact test, have good bonding strength, and have excellent structural strength; while cases whose calculated σ values ​​do not meet the requirement of ≥4MPa cannot pass the mechanical impact test.

[0081] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A battery pack, characterized in that, include: Box; A battery unit is housed in the housing. The battery unit includes multiple batteries, including a first battery and a second battery, which are arranged alternately. The first battery and the second battery each include a housing and an insulating film covering the outer surface of the housing. The insulating film covering the housing of the second battery has a cutout area on the bottom and lower side of the second battery, so that the area of ​​the housing of the second battery corresponding to the cutout area is exposed to the insulating film. Structural adhesive is disposed between the bottom surface of the first battery, the bottom surface of the second battery, and the housing, and covers the hollow area of ​​the second battery, for fixing the first battery and the second battery to the housing; A first limiting strip may or may not be provided between the bottom surface of each battery and the housing; (1) When the number of the first battery and the number of the second battery in the battery cell are equal, the following relationship is satisfied: (2) When the number of the first batteries in the battery cell is K and the number of the second batteries is K+1, where K≥1, the following relationship is satisfied: (3) When the number of the first batteries in the battery cell is K+1 and the number of the second batteries is K, where K≥1, the following relationship is satisfied: In the above formula, σ1 is the bonding strength of the insulating film to the box body through the structural adhesive, σ2 is the bonding strength of the shell to the box body through the structural adhesive, S is the bottom area of ​​a single battery, S1 is the contact area between a single first limiting strip and the bottom surface of a single battery, and n1 is the number of first limiting strips corresponding to the bottom surface of a single battery.

2. The battery pack according to claim 1, characterized in that, The number of battery cells is multiple, and the multiple battery cells are arranged side by side; between two adjacent rows of battery cells, the first battery and the second battery are arranged alternately.

3. The battery pack according to claim 2, characterized in that, The battery cells in two adjacent columns are connected by a second buffer pad.

4. The battery pack according to claim 3, characterized in that, The second buffer pad connects the two adjacent rows of battery cells into one unit by means of adhesive bonding.

5. The battery pack according to any one of claims 1-4, characterized in that, In the battery cell, the adjacent first battery and second battery are connected by a first buffer pad.

6. The battery pack according to claim 5, characterized in that, A support structure is provided on the outside of the battery cell to keep the first buffer pad in a compressed state; And / or, the first buffer pad connects the first battery and the second battery in the battery cell into one unit by means of adhesive bonding.

7. The battery pack according to any one of claims 1-4, characterized in that, An insulating coating is provided on the surface of the housing corresponding to the bottom surface of the first battery and the bottom surface of the second battery.

8. The battery pack according to any one of claims 1-4, characterized in that, Inside the housing, a second limiting strip is provided on the outside of the battery cell located on the outer side to limit the overflow height of the structural adhesive and to allow the structural adhesive to cover the hollow area.

9. The battery pack according to any one of claims 1-4, characterized in that, The rounded corner area on the lower side of the second battery is located within the hollowed-out area.

10. The battery pack according to any one of claims 1-4, characterized in that, 0 ≤ n1S1 / S×100% ≤ 30%; And / or, 0 MPa < σ1 < 3 MPa, σ2 ≥ 6 MPa; And / or, the material of the structural adhesive is selected from one or more of polyurethane and epoxy resin; And / or, the thickness of the first buffer pad is 0.5-1.5 mm; And / or, the thickness of the second cushioning pad is 0.5-5mm; And / or, the thickness of the insulating film is 0.015-0.2 mm.

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