Battery pack

Abstract

According to the battery pack provided by the invention, the battery pack has relatively good bonding strength, so that the safety performance of the battery pack is improved. The invention provides a battery pack. The battery pack comprises a box body; the battery unit is accommodated in the box body, the battery unit comprises a plurality of batteries, the plurality of batteries comprise first batteries and second batteries, and the first batteries and the second batteries are alternately arranged; the first battery and the second battery respectively comprise a shell and an insulating film covering the outer surface of the shell, and the insulating film covering the shell of the second battery is provided with a hollow area corresponding to the bottom surface and the side surface of the lower part of the second battery; the structural adhesive is used for fixing the first battery and the second battery on the box body; and a first limiting strip is arranged or not arranged between the bottom surface of each battery and the box body.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery pack. Background Art

[0002] At present, in order to improve assembly efficiency and reduce costs, many power battery packs directly integrate batteries into the box, namely the CTP (Cell to PACK) structure, which simplifies the original battery module design, thereby reducing parts, improving integration efficiency and energy density, and reducing costs.

[0003] The batteries in CTP battery packs are usually fixed to the box by gluing. The battery shell is usually made of metal materials (such as aluminum, etc.). Since the battery has high requirements for insulation, an insulating film is usually coated on the sides and bottom of the battery. However, the bonding strength between the insulating film and the structural adhesive is relatively weak. During long-term use, the battery pack is prone to bonding failure, causing safety problems. In order to increase the structural strength of the battery pack, some CTP battery packs will add a pressure strip on the top of the battery. This solution increases the complexity of the CTP structure, resulting in a decrease in grouping efficiency, while also increasing the cost of the battery pack, and the improvement in structural strength is also limited. Summary of the invention

[0004] In order to solve at least one of the deficiencies in the prior art, the present invention provides a battery pack having better bonding strength, thereby facilitating improving the safety performance of the battery pack.

[0005] To achieve the purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a battery pack, comprising:

[0007] Box;

[0008] A battery unit, the battery unit is accommodated in the box, the battery unit includes a plurality of batteries, the plurality of batteries include a first battery and a second battery, the first battery and the second battery are arranged alternately; the first battery and the second battery respectively include a shell and an insulating film covering the outer surface of the shell, and the insulating film covering the shell of the second battery is provided with a hollow area on the side surface corresponding to the bottom surface and the lower part of the second battery, so that the shell of the second battery The area corresponding to the hollow area is exposed to the insulating film;

[0009] Structural adhesive, disposed between the bottom surface of the first battery, the bottom surface of the second battery and the box body, and covering the hollow area of ​​the second battery, for fixing the first battery and the second battery to the box body;

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

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

[0012]

[0013] (2) When the number of the first batteries in the battery unit 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 unit 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 relationship, σ1 is the bonding strength of the insulating film bonded to the box body by the structural adhesive, σ2 is the bonding strength of the shell bonded to the box body by the structural adhesive, S is the bottom area of ​​a single battery, S1 is the contact area between a single first limit strip and the bottom surface of a single battery, and n1 is the number of the first limit strips provided corresponding to the bottom surface of a single battery.

[0018] In some embodiments, there are multiple battery cells, and the multiple battery cells are arranged in parallel; between two adjacent columns of battery cells, the first batteries and the second batteries are arranged alternately.

[0019] Preferably, two adjacent columns of battery cells are connected via a second buffer pad.

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

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

[0022] Preferably, a support structure capable of keeping the first buffer pad in a compressed state is provided on the outer side of the battery unit;

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

[0024] Preferably, the surface of the box body 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, in the box, a second limiting strip for limiting the overflow height of the structural adhesive is provided on the outer side of the battery unit located on the outer side, so that the structural adhesive can cover the hollow area.

[0026] Furthermore, a rounded area on the side surface of the lower portion of the second battery is located within the hollow area.

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

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

[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 cushion is 0.5-5 mm;

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

[0033] The technical solution provided by the present 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, and the corresponding calculation results are made ≥ 4MPa by reasonably setting the relevant parameters in the above-mentioned relationship formulas. This can achieve the purpose of improving the safety performance of the battery pack and improving the structural strength of the battery pack. At the same time, it also greatly reduces the design cost and is conducive to improving development efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0038] Figure 4 A schematic side view of two columns of battery subunits arranged in parallel;

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

[0040] Figure numerals: battery cell 100, first battery 1, second battery 2, shell 3, insulating film 4, lower side 5, bottom 6, side 7, box body 8, first buffer pad 9, end plate 10, beam 11, structural adhesive 12, first limit strip 13, second limit strip 14, hollow area 15, second buffer pad 16, insulating coating 17. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes 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, bottom, etc. mentioned or may be mentioned in this specification are defined relative to the structures shown in the drawings. They are relative concepts and may change accordingly according to their different positions and different usage states. The words "inside" and "outside" refer to the directions toward or away from the geometric center of a specific component, respectively. In addition, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

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

[0045] The battery unit 100 is contained in the box 8. Figure 3, each battery cell 100 includes a plurality of batteries, wherein the plurality of batteries include 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 shell 3 and an insulating film 4 coated on the outer surface of the shell 3. Similarly, the second battery 2 also includes a shell 3 and an insulating film 4 coated on the outer surface of the shell 3, and the difference from the first battery 1 is that: the insulating film 4 of the second battery 2 is provided with a hollow area 15, specifically, the insulating film 4 is provided with a hollow area 15 corresponding to the bottom surface 6 and the lower side surface 5 of the second battery 2, so that the shell 3 of the second battery 2 corresponding to the position of the hollow area 15 is exposed to the insulating film 4, and the surface of the shell 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 a hollow area 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 box body 8, that is, structural adhesive 12 is provided between the bottom surface 6 of the first battery 1 and the box body 8, and between the bottom surface 6 of the second battery 2 and the box body 8, and the structural adhesive 12 can cover the hollow area 15 of the insulating film 4 of the second battery 2, so that the exposed bottom surface 6 of the shell 3 of the second battery 2 and the lower side surface 5 of the shell 3 are covered by the structural adhesive 12; the first battery 1 and the second battery 2 are fixed to the box body 8 by the structural adhesive 12. Optionally, a first limiting strip 13 is provided between the bottom surface 6 of each battery and the box body 8, that is, the first limiting strip 13 may be provided or not provided.

[0046] In the battery pack of the present invention, the first battery 1 without the hollow area 15 and the second battery 2 with the 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 the first battery 1 and the second battery 2 in the battery unit 100 is equal, σ1, σ2, S, S1, and n1 satisfy the following relationship (1), the battery pack has better bonding strength, the overall structural strength of the battery pack is improved, and the mechanical impact test requirements of GB / T 31467.3 7.2 can be met, the battery pack can resist mechanical impact, and successfully pass the mechanical impact test:

[0048]

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

[0050]

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

[0052]

[0053] In the above relationship, the bonding strength of the insulating film 4 bonded to the box body 8 by the structural adhesive 12 is σ1, in MPa; the bonding strength of the housing 3 bonded to the box body 8 by the 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 is not provided with a first limiting strip 13, n1=0.

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

[0055] Preferably, in the battery unit 100, a first buffer pad 9 is provided between adjacent batteries, and the adjacent first batteries 1 and second batteries 2 are connected as a whole through the first buffer pad 9. Specifically, the first buffer pad 9 is connected to the adjacent first batteries 1 and second batteries 2 by bonding, so that the first batteries 1 and second batteries 2 in the battery unit 100 are alternately connected as a whole, 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 may be one or more, such as Figure 4 , 5As shown, when a plurality of battery cells 100 are provided, the plurality of battery cells 100 are arranged in parallel, and between two adjacent columns of battery cells 100, the first battery 1 and the second battery 2 are arranged alternately; specifically, the plurality of battery cells 100 arranged in parallel include a plurality of rows and columns of batteries, and the first battery 1 and the second battery 2 are arranged alternately in each row and column of batteries, as well as between adjacent rows and columns of batteries.

[0057] Preferably, a second buffer pad 16 is provided between two adjacent columns of battery cells 100, and the adjacent battery cells 100 are connected by the second buffer pad 16. Specifically, for example, the second buffer pad 16 is connected to the battery cells 100 on both sides by bonding, so that each battery cell 100 is connected as a whole, 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 plays the role of heat insulation buffer to ensure 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 capable of keeping the first buffer pad 9 in a compressed state is provided on the outside of the battery cell 100. The support structure is, for example, an end plate 10 provided on the outside of the battery cell 100, and a beam 11 or the like may also be provided on the outside of the end plate 10 to provide support for the battery packaging box state; after the battery pack is assembled, the support structure plays a supporting and insulating role, and makes the first buffer pad 9 between the first battery 1 and the second battery 2 of the battery cell 100 in a compressed state, with a certain amount of compression and resilience, so that the two adjacent batteries form a whole. The first buffer pad 9 also plays a heat-insulating buffer role and ensures the gap between the two adjacent batteries. The first battery 1 and the second battery 2 in the battery cell 100 are bound together by the first buffer pad 9 and the second buffer pad 16, so that the first battery 1 with relatively weak adhesion and the second battery 2 with relatively strong adhesion can be regarded as a whole, which greatly improves the structural strength of the batteries after being stacked into groups. The first batteries 1 and the second batteries 2 are mixed and assembled alternately, and the first buffer pads 9 and the second buffer pads 16 are used to connect the rows and columns of batteries into one. With or without the first limit strip 13, the battery pack is designed by adaptively combining the above three relationship equations and making σ≥4MPa. A battery pack with reliable bonding strength and good safety can be obtained. The implementation method of the scheme of the present invention is simple, the required parts are few, the cost is low, and the integration efficiency and design efficiency of the battery pack can be greatly improved, and the cost can be reduced.

[0059] In some embodiments, the surface of the box body 8 corresponding to the bottom surface 6 of the first battery 1 and the bottom surface 6 of the second battery 2 is provided with an insulating coating 17, that is, the surface of the box body 8 corresponding to the bottom surface 6 of the first battery 1 and the surface of the box body 8 corresponding to the bottom surface 6 of the second battery 2 are provided with an insulating coating 17. Providing the insulating coating 17 is beneficial to enhancing the insulation effect.

[0060] In some embodiments, in the box body 8, a second limit strip 14 is provided on the outside of the battery cell 100 located on the outside to limit the overflow height of the structural adhesive 12, and the structural adhesive 12 can cover the hollow area 15 of the second battery 2, specifically, the structural adhesive 12 can cover the surface of the shell 3 corresponding to the hollow area 15. The height of the second limit 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 limit strip 14 can be specifically set to match the row or column of batteries corresponding to the position.

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

[0062] In the present invention, there is no special restriction on the specific materials of the insulating film 4, the insulating coating 17, the structural adhesive 12, etc., and the corresponding materials applicable in the art can be used. 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 limit strip 13 and the second limit strip 14 can both be materials known in the art, such as, but not limited to, polycarbonate (PC) or other hard 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 shell can be, for example, aluminum or steel, and the material of the box can be, for example, aluminum or steel.

[0063] Preferably, 0Mpa<σ1<3Mpa, σ2≥6Mpa; the thickness of the first buffer pad 9 is, for example, 0.5-1.5mm; the thickness of the second buffer pad 16 is, for example, 0.5-5mm; the thickness of the insulating film 4 is, for example, 0.015-0.2mm. There is no particular restriction on the number of first limit bars 13 between the bottom surface 6 of a single battery and the box body 8, for example, 0, 1, or more, for example, 1-4, for example, 1, 2, 3, 4, etc. In some examples, the height of the first limit bar 13 is, for example, 0.5-2.5mm, and the thickness of the structural adhesive 12 is, for example, 0.5-2.5mm.

[0064] In a test example of the present application, structural adhesive A and structural adhesive B were used respectively. Figure 1-5 The experiment was conducted in the battery pack shown in the figure, where the material of structural adhesive A and structural adhesive B is polyurethane structural adhesive, and no insulating coating is provided. The material of the battery shell is aluminum, the material of the box is aluminum, the material of the first limit strip is polycarbonate (PC), and the material of the insulating film is polyester resin (PET). The parameters of the battery pack are shown in Table 1 below:

[0065] Table 1

[0066]

[0067]

[0068] This test case conducts 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 the first limiting strips 13 provided on the bottom surface 6 of a single battery, multiple groups of experiments were carried out under different conditions of n1S1 / S×100%. The calculated value of σ corresponding to each group of experiments was calculated using the relationship (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 provided corresponding to the bottom surface 6 of a single battery, multiple groups of experiments were carried out under different conditions of n1S1 / S×100%, and the calculated value of σ corresponding to each group of experiments was calculated using the relationship (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 provided corresponding to the bottom surface 6 of a single battery, multiple groups of experiments were carried out under different conditions of n1S1 / S×100%, and the calculated value of σ corresponding to each group of experiments was calculated using the relationship (3). The specific test results are shown in Table 4:

[0077] Table 4 (Relationship (3))

[0078]

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

[0080] It can be seen from the above experimental results that all battery packs whose σ calculated values ​​satisfy ≥4MPa calculated by equations (1)-(3) can pass the mechanical impact test, have good bonding strength, and have excellent battery pack structural strength; while cases where the σ calculated values ​​do not satisfy ≥4MPa cannot pass the mechanical impact test.

[0081] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

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

2. The battery pack according to claim 1, characterized in that: There are multiple battery cells, and the multiple battery cells are arranged in parallel; between two adjacent columns of battery cells, the first batteries and the second batteries are arranged alternately.

3. The battery pack according to claim 2, characterized in that: Two adjacent columns of battery cells are connected via a second buffer pad.

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

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

6. The battery pack according to claim 5, characterized in that: A support structure capable of keeping the first buffer pad in a compressed state is provided on the outer side of the battery unit; And / or, the first buffer pad connects the first battery and the second battery in the battery unit into one body by bonding.

7. The battery pack according to any one of claims 1 to 4, characterized in that: An insulating coating is provided on the surface of the box body 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 to 4, characterized in that: In the box, a second limiting strip for limiting the overflow height of the structural adhesive is provided on the outer side of the battery unit located on the outer side, so that the structural adhesive can cover the hollow area.

9. The battery pack according to any one of claims 1 to 4, characterized in that: The rounded area of ​​the side surface of the lower portion of the second battery is located in the hollow area.

10. The battery pack according to any one of claims 1 to 4, characterized in that: 0≤n1S1 / S×100%≤30%; and / or, 0Mpa<σ1<3Mpa, σ2≥6Mpa; 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 cushion is 0.5-5 mm; And / or, the thickness of the insulating film is 0.015-0.2 mm.

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