Battery pack

Abstract

According to the battery pack provided by the invention, the battery pack has good insulating strength, so that the safety performance of the battery pack is improved. The battery pack comprises a box body, a battery array and a structural adhesive; the battery array is accommodated in the box body, the battery array comprises a plurality of battery units which are arranged in parallel, each battery unit comprises a plurality of batteries, the plurality of batteries comprise first batteries and second batteries, the first batteries and the second batteries are arranged alternately, and the first batteries and the second batteries are arranged alternately. The adjacent first battery and second battery are connected through a first buffer pad; the first battery and the second battery respectively comprise a shell and a first insulating film covering the outer surface of the shell; the structural adhesive is used for fixing the first battery and the second battery on the box body; moreover, among the respective second batteries of the battery array, the second battery having the largest number m of adjacent second batteries satisfies the following relational expression (1): # imgabs0 #

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] In the CTP structure, the battery is generally fixed to the box by gluing, and the battery shell is generally made of metal materials (such as aluminum, etc.). Since the battery has high requirements for insulation, the side and bottom of the battery are usually wrapped with an insulating film. However, the bonding strength between the insulating film and the structural adhesive is relatively weak, and the battery pack is prone to bonding failure during long-term use. Therefore, in order to improve the bonding strength between the battery and the battery box, the insulating film on the bottom of the battery is usually removed to fix it to the battery box through the metal surface at the bottom of the battery, thereby improving the bonding strength of the battery. On the one hand, the battery box is generally made of metal, so the two exposed metal surfaces are prone to poor insulation problems; on the other hand, there are usually rounded corners around the bottom of the battery. Considering the tolerance problem during the production process, the insulating film on the side of the battery usually exposes the rounded corners of the bottom of the battery to prevent the formation of overhangs or wrinkles at the rounded corners; this design easily leads to insufficient insulation between the exposed rounded corners of two adjacent batteries in the battery pack, thereby causing safety problems. 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 good insulation 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, including a box, a battery array and a structural adhesive:

[0007] The battery array is accommodated in the box, and the battery array includes a plurality of battery units arranged in parallel, each of the battery units includes a plurality of batteries, the plurality of batteries include a first battery and a second battery, and the first battery and the second battery are arranged alternately; between two adjacent columns of the battery units, the first battery and the second battery are arranged alternately;

[0008] The first battery and the second battery respectively include a shell and a first insulating film covering the outer surface of the shell, and the first insulating film covering the shell of the second battery is provided with a hollow area on the side corresponding to the bottom surface and the lower part of the second battery, and the edge fillet of the side of the lower part of the second battery is located in the hollow area, so that the area of ​​the shell of the second battery corresponding to the hollow area is exposed to the first insulating film;

[0009] The structural adhesive is disposed between the bottom surface of the first battery, the bottom surface of the second battery and the box body, and covers the hollow area of ​​the second battery, and is used to fix the first battery and the second battery to the box body;

[0010] Furthermore, among the second batteries of the battery array, there are second batteries with the largest number m of adjacent second batteries that satisfy the following relational expression (1):

[0011]

[0012] Among them, R bc is the approximate calculated value of the insulation resistance between the second battery and the box, R bb2 is an approximate calculated value of the insulation resistance between two adjacent second batteries.

[0013] Furthermore, the adjacent first battery and the second battery are connected via a first buffer pad;

[0014] The battery cells in two adjacent columns are connected via a second buffer pad;

[0015] The bottom surface of the box and the first battery and the surface corresponding to the bottom surface of the second battery are provided with or without an insulating coating;

[0016] A first limiting strip may or may not be provided between the bottom surface of each battery and the box body.

[0017] Furthermore, in equation (1), R bb2 Calculate according to the following relationship (2):

[0018]

[0019] In the relationship (2), ρ2 is the volume resistivity of the structural adhesive, r2 is the radius of the edge fillet of the side of the battery, L1 is the thickness of the first insulating film, W1 is the thickness of the first buffer pad, W2 is the thickness of the second buffer pad, and H3 is the height of the hollow area.

[0020] Furthermore, when the insulating coating is not provided, R in the relation (1) bcCalculate according to the following relationship (3):

[0021]

[0022] When the insulating coating is provided, R in the relation (1) bc Calculate according to the following relationship (4):

[0023]

[0024] In the above-mentioned equations (3) and (4), ρ1 is the volume resistivity of the first limit strip, ρ2 is the volume resistivity of the structural adhesive, H1 is the thickness of the structural adhesive from the bottom surface of a single battery to the box body, S is the bottom surface area of ​​a single battery, n1 is the number of the first limit strips corresponding to the bottom surface of a single battery, S1 is the contact area between a single first limit strip and the bottom surface of a single battery, ρ3 is the volume resistivity of the insulating coating, and L2 is the thickness of the insulating coating.

[0025] Preferably, the first buffer pad connects the first battery and the second battery in the battery unit into one by bonding;

[0026] And / or, the second buffer pad connects two adjacent columns of battery cells into one by bonding;

[0027] And / or, a support structure capable of keeping the first buffer pad in a compressed state is provided on the outer side of the battery unit.

[0028] Furthermore, the rounded area at the bottom of the second battery is located in the hollow area.

[0029] Preferably, the second battery of each battery unit comprises a side surface facing the battery unit of an adjacent column, and the rounded edge of the lower portion of the shell of the second battery corresponding to the hollowed-out area of ​​the side surface is covered by the second insulating film.

[0030] Preferably, between two adjacent columns of battery cells, each battery comprises a side surface facing the battery cells in the adjacent column, and a lower edge fillet of the side surface is covered by a second insulating film;

[0031] In the battery cell located on the outside, the lower edge rounding of the side surface opposite to the side surface of the battery cell provided with the second insulating film is also covered by the second insulating film.

[0032] 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.

[0033] In some embodiments, ρ1≥1×10 13 Ω·cm, ρ2≥7.5×10 9 Ω·cm, ρ3≥1×10 13 Ω·cm;

[0034] And / or, the material of the structural adhesive is selected from one or more of polyurethane and epoxy resin;

[0035] and / or, the thickness W1 of the first buffer pad is 0.5-1.5 mm;

[0036] and / or, the thickness W2 of the second buffer pad is 0.5-5 mm;

[0037] and / or, the thickness L1 of the first insulating film is 0.015-0.2 mm;

[0038] And / or, the thickness H1 of the structural adhesive between the bottom surface of a single battery and the box body is 0.5-2.5 mm;

[0039] And / or, the thickness L2 of the insulating coating is 0.1-0.3 mm;

[0040] And / or, the height H2 of the second limiting strip satisfies: H1+r1≤H2≤H1+r1+3mm, where r1 is the fillet radius of the bottom of the battery;

[0041] And / or, the height H3 of the hollow area satisfies: r1<H3≤H2, where r1 is the fillet radius of the bottom of the battery;

[0042] And / or, 0<r2≤3.5mm.

[0043] The technical solution provided by the present invention has the following beneficial effects:

[0044] 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 requirements of the relationship (1) are met by reasonably setting relevant parameters, thereby achieving the purpose of improving the safety performance of the battery pack, improving the insulation strength of the battery pack, and having good structural strength, while also greatly reducing the design cost and facilitating improving development efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic front view of a first battery in one embodiment;

[0046] Figure 2 is a schematic front view of a second battery in one embodiment;

[0047] Figure 3is a schematic top view of a battery when not coated with the first insulating film;

[0048] Figure 4 is a schematic diagram of a battery pack in one embodiment;

[0049] Figure 5 A schematic side view of two columns of battery cells arranged in parallel;

[0050] Figure 6 For Figure 5 A schematic diagram of adding a second insulating film on the basis;

[0051] Figure 7 for Figure 5 Bottom schematic diagram of the battery array;

[0052] Figure 8 The bottom schematic diagram of a battery array with three columns of battery cells arranged in parallel.

[0053] Fig. 9 Calculating an equivalent shape for the insulation resistance between two adjacent second batteries;

[0054] Fig.10 for Fig. 9 The simplified shape of

[0055] Fig.11 for Fig. 9 The enlarged schematic diagram at A in the middle;

[0056] Fig.12 for Fig.10 Enlarged schematic diagram of point B in the middle.

[0057] Figure numerals: battery cell 100, first battery 1, second battery 2, 2a, 2b, shell 3, first insulating film 4, lower side 5, bottom 6, side 7, box 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, second insulating film 18, battery array 19. DETAILED DESCRIPTION

[0058] 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.

[0059] 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.

[0060] 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.

[0061] See also Figure 1-8 The battery pack provided by the present invention includes a box body 8, a battery array 19 and a structural adhesive 12.

[0062] The battery array 19 is contained in the box 8. Figure 5 , Figure 7 , Figure 8 The battery array includes a plurality of battery cells 100 arranged in parallel. Figure 4 Each battery unit 100 includes a plurality of batteries, wherein the plurality of batteries include a first battery 1 and a second battery 2. In each battery unit 100, the first battery 1 and the second battery 2 are alternately arranged to form a row of batteries; and a first buffer pad 9 is provided between adjacent batteries, and the adjacent first battery 1 and the second battery 2 are connected together through the first buffer pad 9. Figure 7 , Figure 8 , between two adjacent columns of battery cells 100, the first battery 1 and the second battery 2 are also arranged alternately. Specifically, the plurality of battery cells 100 arranged in parallel include multiple rows and columns of batteries, and the first battery 1 and the second battery 2 are arranged alternately in each row of batteries, each column of batteries, and between adjacent rows of batteries and between adjacent columns of batteries. A second buffer pad 16 is provided between two adjacent columns of battery cells 100, and the two adjacent columns of battery cells 100 are connected into one by the second buffer pad 16.

[0063] The first battery 1 includes a shell 3 and a first insulating film 4 coated on the outer surface of the shell 3. Similarly, the second battery 2 also includes a shell 3 and a first insulating film 4 coated on the outer surface of the shell 3, and the difference from the first battery 1 is that: the first insulating film 4 of the second battery 2 is provided with a hollow area 15, specifically, the first insulating film 4 is provided with a hollow area 15 corresponding to the bottom surface 6 and the lower side 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 first insulating film 4, and the surface of the shell 3 of the second battery 2 in these areas is not covered by the first insulating film 4, specifically, the edge fillet of the side 5 of the lower part of the second battery 2 is located in the hollow area 15, that is, the edge fillet of the side 5 of the lower part of the second battery 2 is not covered by the first insulating film 4, specifically, the lower side 5 is the side part of the bottom of the shell of the second battery; specifically, the fillet area of ​​the bottom of the second battery 2 is located in the hollow area 15. The first 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 first insulating film 4. Structural adhesive 12 is provided between the bottom surface of the first battery 1, the bottom surface 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 first 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 side surface 5 of the lower part 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. A first limit strip 13 may be provided between the bottom surface 6 and the box body 8 of each battery, or the first limit strip 13 may not be provided; as Figure 4 In the example shown, a first limiting strip 13 is provided between the bottom surface 6 of each battery and the box body 8 .

[0064] 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 may be provided with an insulating coating 17, or may not be provided with an insulating coating 17. Figure 4 In the example shown, an insulating coating 17 is provided on the surface of the case 8 corresponding to the bottom surface 6 of the first battery 1 and on the surface of the case 8 corresponding to the bottom surface 6 of the second battery 2 .

[0065] In the present invention, among the second batteries included in the battery array of the battery pack, there are second batteries with the largest number m of adjacent second batteries that satisfy the following relationship (1):

[0066]

[0067] Among them, R bc is the calculated value of the insulation resistance between the second battery and the box, R bb2is the approximate calculated value of the insulation resistance between two adjacent second batteries.

[0068] Specifically, Figure 7 For example, the battery array includes a plurality of second batteries 2, some of which are adjacent to one second battery from a battery cell in an adjacent column, and some of which, such as the second battery 2a, are adjacent to two second batteries from battery cells in an adjacent column. Figure 7 The battery array shown has the most adjacent second batteries, and the number of adjacent second batteries is 2. Figure 7 In the example of , the second battery 2a needs to satisfy the above relationship (1), where m=2, that is, m is the number of second batteries adjacent to the second battery 2a. Figure 8 For example, in the battery array, the second battery with the largest number of adjacent second batteries is the second battery 2b, which is adjacent to four second batteries from battery cells in adjacent columns. The second battery 2b needs to satisfy the above relationship (1), where m=4.

[0069] Among them, R in equation (1) bb2 Calculate according to the following relationship (2):

[0070]

[0071] When the insulating coating 17 is not provided, R in the relation (1) bc Calculate according to the following relationship (3):

[0072]

[0073] When the insulating coating 17 is provided, R in the relation (1) bc Calculate according to the following relationship (4):

[0074]

[0075] In the above relationship, the volume resistivity of the first limit strip 13 is ρ1, in Ω·cm; the volume resistivity of the structural adhesive 12 is ρ2, in Ω·cm; the thickness of the structural adhesive 12 between the bottom surface 6 of a single battery and the box body 8 is H1, in cm; the area of ​​the bottom surface 6 of a single battery is S, in cm 2 ; The number of first limiting strips 13 corresponding to the bottom surface 6 of a single battery is n1; the contact area between a single first limiting strip 13 and the bottom surface 6 of a single battery is S1, in cm 2; The volume resistivity of the insulating coating 17 is ρ3, in Ω·cm; The thickness of the insulating coating 17 is L2, in cm; The radius of the edge fillet of the side 5 of the battery is r2, that is, the fillet radius of the edge between two adjacent sides of the battery (such as Figure 7 The thickness of the first insulating film 4 is L1, and the unit is cm; the thickness of the first buffer pad 9 is W1, and the unit is cm; the thickness of the second buffer pad 16 is W2, and the unit is cm; the height of the hollow area 15 is H3, and the unit is cm.

[0076] In this article, the edge fillet of the side of the battery refers to the fillet between two adjacent side surfaces of the battery, and r2 is the radius of the fillet, see Figure 3 In the text, the fillet at the bottom of the battery refers to the fillet at the intersection of the bottom surface of the battery and the side surface of the battery, and r1 is the radius of the fillet, see Figure 2 's hint.

[0077] 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, and the first battery 1 and the second battery 2 in the battery unit 100 are preferably connected as a whole through the first buffer pad 9; the battery units 100 in adjacent columns are preferably connected as a whole through the second buffer pad 16; the battery pack structure has good structural strength. In the present invention, the battery pack is calculated by the above relationship to satisfy The battery pack has better insulation strength, which can avoid insulation failure in the battery pack and effectively ensure the safety performance of the battery pack.

[0078] In the above relation (1), let That is, R≥10MΩ. The larger the calculated value of R, the greater the insulation strength of the battery pack. In order to meet the need for good insulation strength, the values ​​of various related parameters can be reasonably set through equations (1)-(4) to obtain a calculated value of R that meets the requirements, thereby achieving the purpose of improving the insulation safety of the battery. The implementation method of the solution of the present invention is simple, requires fewer parts, and has low cost. It can greatly improve the integration efficiency and design efficiency of the battery pack and reduce costs.

[0079] For ease of understanding, the following Figure 9-12 The approximate calculated value R of the insulation resistance between two adjacent second batteries in the present invention is bb2 The calculation origin of is introduced as follows:

[0080] Fig. 9 Schematic diagram of the bottom surface distribution of four adjacent batteries between two adjacent columns of battery cells 101 and 102; the equivalent insulation resistance of the structural adhesive between the hollow areas of two adjacent second batteries 2 between two columns of battery cells can be equivalent to Fig. 9The gray area circled in the figure is calculated and its insulation resistance is recorded as R bb1 . See Fig.11 , the method for extracting the shape of the gray area is as follows: O1 and O2 are the center points of the rounded corners r2 of two adjacent first batteries 1 in the two columns of battery cells 101 and 102 respectively; connect O1 and O2 to make an auxiliary line segment O1O2, make a tangent line a1b1 through the rounded corner r2 (including the first insulating film) of the first battery 1 of the battery cell 102, and be perpendicular to O1O2, point a1 is the intersection of a1b1 and the side of the second battery 2 in the battery cell 101, and point b1 is the intersection of a1b1 and the side of the second battery 2 in the battery cell 102; through the rounded corner r2 of the first battery 1 in the battery cell 101 2 (including the first insulating film) is tangent c1d1 and is perpendicular to O1O2, point c1 is the intersection (intersection line) of c1d1 and the side of the second battery 2 of the battery cell 102, and point d1 is the intersection of c1d1 and the side of the second battery 2 of the battery cell 101; a1 and d1 form a curve with the tangent of the side of the second battery 2 of the battery cell 101, and b1 and c1 form a curve with the tangent of the side of the second battery 2 of the battery cell 102; finally, the cross-sectional shape a1b1c1d1 of the equivalent body for calculating the insulation resistance of two adjacent second batteries 2 between two columns of battery cells 101 and 102 is obtained. Because its shape is relatively complex, the inventor simplifies its shape as follows: Fig.10 The shape of the gray area circled in the figure, the insulation resistance corresponding to the simplified shape is recorded as R bb2 , the simplified shape can be found in Fig.12 , its shape features are as follows: O1 and O2 are the center points of the rounded corners r2 of two adjacent first batteries 1 in the two columns of battery cells 101 and 102 respectively; connect O1 and O2 to form an auxiliary line segment O1O2; line segment a2d2 is parallel to O1O2 and tangent to the rounded corner of the side of the second battery 2 in the battery cell 101; line segment b2c2 is parallel to O1O2 and tangent to the rounded corner of the side of the second battery 2 in the battery cell 102; line segment a2b2 is perpendicular to O1O2 and tangent to the rounded corner of the side of the first battery 1 in the battery cell 102; line segment c2d2 is perpendicular to O1O2 and tangent to the rounded corner of the side of the first battery 1 in the battery cell 101. bb1 >R bb2 , so we only need to confirm R bb2 Meeting the insulation performance requirements ensures R bb1 It also meets the insulation performance requirements, which simplifies the calculation. bb2 The calculation formula of is shown in the above relation (2).

[0081] In some embodiments, the first buffer pad 9 connects the first battery 1 and the second battery 2 in the battery unit 100 into one piece by bonding, for example, by gluing. By alternately connecting the first batteries 1 and the second batteries 2 in the battery unit 100 into one piece, the structural strength of the entire battery pack can be improved, and the safety of the battery pack can be improved.

[0082] In some embodiments, the second buffer pad 16 is bonded, for example, by adhesive bonding, to connect two adjacent columns of battery cells 100. Specifically, 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 acts as a heat-insulating 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 first 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.

[0083] 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 located on the outside, 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, so as to obtain a battery pack with better bonding strength.

[0084] Some examples include Figure 6As shown, there are multiple battery cells 100, and the second battery 2 of each battery cell 100 includes a side surface facing the battery cell 100 in an adjacent column, and the lower edge fillet of the shell 3 of the second battery 2 corresponding to the hollow area 15 of the side surface is covered by the second insulating film 18, which can further improve the insulation strength. Further preferably, between two adjacent columns of battery cells 100, each battery includes a side surface facing the battery cell 100 in an adjacent column, and the lower edge fillet of the side surface is covered by the second insulating film 18, which can further improve the insulation strength; in the battery cell located on the outside, the lower edge fillet of the side surface on the opposite side of the side surface of the battery provided with the second insulating film 18 is also covered by the second insulating film 18.

[0085] In the present invention, 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 or without an insulating coating 17. When the insulating coating 17 is provided, it is beneficial to further enhance the insulation effect.

[0086] 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.

[0087] In the present invention, there is no particular restriction on the specific materials of the first insulating film 4, the second insulating film 18, 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 first insulating film 4 or the second insulating film 18 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 3 can be, for example, aluminum or steel, and the material of the box body 8 can be, for example, aluminum or steel.

[0088] In some examples, ρ1 is, for example, ≥ 1×10 13 Ω·cm, the ρ2 is, for example, ≥7.5×10 9Ω·cm, the ρ3 is, for example, ≥1×10 13 Ω·cm; the thickness W1 of the first buffer pad 9 is, for example, 0.5-1.5mm; the thickness W2 of the second buffer pad 16 is, for example, 0.5-5mm; the thickness L1 of the first insulating film 4 is, for example, 0.015-0.2mm; the thickness H1 of the structural adhesive 12 between the bottom surface 6 of a single battery and the box body 8 is, for example, 0.5-2.5mm, and when a first limit strip 13 is provided, H1 is also the height of the first limit strip 13; the thickness L2 of the insulating coating 17 is, for example, 0.1-0.3mm; the height H2 of the second limit strip 14 satisfies: H1+r1≤H2≤H1+r1+3mm, r1 is the fillet radius of the bottom of the battery; the height H3 of the hollow area 15 satisfies: r1<H3≤H2; the radius r2 of the edge fillet of the side 5 of the battery is 0<r2≤3.5mm. The number of first limiting bars 13 between the bottom surface 6 of a single battery and the box body 8 is not particularly limited, for example, 0, 1, or multiple, for example, 2-4, for example, 2, 3, 4, etc. In some examples, the edge fillet radius r1 of the bottom surface 6 of the battery is 0<r1≤3.5mm.

[0089] Example:

[0090] In one embodiment of the present application, the following structural adhesive A, structural adhesive B and first limit strip are respectively used to design a battery pack, and the insulation performance of the battery pack is verified, wherein the schematic diagram of the battery pack is shown in Figure 1-5 , Figure 7-8 :The material of structural adhesive A is polyurethane two-component structural adhesive, and the volume resistivity ρ2 is 7.6x10 9 Ω·cm; the material of structural adhesive B is polyurethane two-component structural adhesive, and the volume resistivity ρ2 is 2.5x10 13 Ω·cm; The height of the first limiting strip 13 is 1 mm, and the volume resistivity ρ1 of the first limiting strip 13 is 1x10 16 Ω·cm. The material of the battery shell 3 is aluminum, and the material of the box body 8 is aluminum. The parameters of the battery pack are shown in Table 1 below:

[0091] Table 1

[0092]

[0093]

[0094] (I) Without insulating coating, by changing the type of structural adhesive 12, 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%, and the R value corresponding to each group of experiments was calculated using the relationship (1), (2), and (3), where Figure 7 The specific test results of the battery pack of the battery array shown are shown in Table 2-1. Figure 8 The specific test results of the battery pack of the battery array shown are shown in Table 2-2. When the R calculated value is calculated by equation (1) in Table 2-1, m=2, and the calculated R calculated value is shown in Table 2-1; when the R calculated value is calculated by equation (1) in Table 2-2, m=4, and the calculated R calculated value is shown in Table 2-2.

[0095] Table 2-1 (without insulating coating, m=2)

[0096]

[0097] Table 2-2 (without insulating coating, m=4)

[0098]

[0099]

[0100] (ii) Assume that the insulating coating has a thickness L2 of 0.15 mm and a volume resistivity ρ3 of 1x10 15 Ω·cm. By changing the type of structural adhesive 12, 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 conducted under different conditions of n1S1 / S×100%, and the R value corresponding to each group of experiments was calculated using the relationship (1), (2), and (4), where Figure 7 The specific test results of the battery pack of the battery array shown are shown in Table 3-1. Figure 8 The specific test results of the battery pack of the battery array shown are shown in Table 3-2. When the R calculated value is calculated by equation (1) in Table 3-1, m=2, and the calculated R calculated value is shown in Table 3-1; when the R calculated value is calculated by equation (1) in Table 3-2, m=4, and the calculated R calculated value is shown in Table 3-2.

[0101] Table 3-1 (with insulating coating, m=2)

[0102]

[0103] Table 3-2 (with insulating coating, m=4)

[0104]

[0105] In Tables 2-1, 2-2, 3-1, and 3-2, the insulation resistance test was performed on the battery packs designed in each experimental group. The measured resistance of the battery packs ≥ 10MΩ was OK, otherwise it was NG, as shown in the "Insulation Resistance Test Results" in the table. It can be seen from the experimental results that the experimental groups with R calculated values ​​≥ 10MΩ designed according to the relationship of the present invention can all pass the insulation test.

[0106] 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: Including box, battery array and structural adhesive: The battery array is accommodated in the box, and the battery array includes a plurality of battery units arranged in parallel, each of the battery units includes a plurality of batteries, the plurality of batteries include a first battery and a second battery, and the first battery and the second battery are arranged alternately; between two adjacent columns of the battery units, the first battery and the second battery are arranged alternately; The first battery and the second battery respectively include a shell and a first insulating film covering the outer surface of the shell, and the first insulating film covering the shell of the second battery is provided with a hollow area on the side corresponding to the bottom surface and the lower part of the second battery, and the edge fillet of the side of the lower part of the second battery is located in the hollow area, so that the area of ​​the shell of the second battery corresponding to the hollow area is exposed to the first insulating film; The structural adhesive is disposed between the bottom surface of the first battery, the bottom surface of the second battery and the box body, and covers the hollow area of ​​the second battery, and is used to fix the first battery and the second battery to the box body; Furthermore, among the second batteries of the battery array, there are second batteries with the largest number m of adjacent second batteries that satisfy the following relational expression (1): Among them, R bc is the calculated value of the insulation resistance between the second battery and the box, R bb2 is an approximate calculated value of the insulation resistance between two adjacent second batteries.

2. The battery pack according to claim 1, characterized in that: The adjacent first battery and the second battery are connected via a first buffer pad; The battery cells in two adjacent columns are connected via a second buffer pad; The bottom surface of the box and the first battery and the surface corresponding to the bottom surface of the second battery are provided with or without an insulating coating; A first limiting strip may or may not be provided between the bottom surface of each battery and the box body.

3. The battery pack according to claim 2, characterized in that: In the relation (1), R bb2 Calculate according to the following relationship (2): In the relationship (2), ρ2 is the volume resistivity of the structural adhesive, r2 is the radius of the edge fillet of the side of the battery, L1 is the thickness of the first insulating film, W1 is the thickness of the first buffer pad, W2 is the thickness of the second buffer pad, and H3 is the height of the hollow area.

4. The battery pack according to claim 3, characterized in that: When the insulating coating is not provided, R in the relation (1) bc Calculate according to the following relationship (3): When the insulating coating is provided, R in the relation (1) bc Calculate according to the following relationship (4): In the above-mentioned equations (3) and (4), ρ1 is the volume resistivity of the first limit strip, ρ2 is the volume resistivity of the structural adhesive, H1 is the thickness of the structural adhesive from the bottom surface of a single battery to the box body, S is the bottom surface area of ​​a single battery, n1 is the number of the first limit strips corresponding to the bottom surface of a single battery, S1 is the contact area between a single first limit strip and the bottom surface of a single battery, ρ3 is the volume resistivity of the insulating coating, and L2 is the thickness of the insulating coating.

5. The battery pack according to any one of claims 2 to 4, characterized in that: The first buffer pad connects the first battery and the second battery in the battery unit into one body by bonding; And / or, the second buffer pad connects two adjacent columns of battery cells into one by bonding; And / or, a support structure capable of keeping the first buffer pad in a compressed state is provided on the outer side of the battery unit.

6. The battery pack according to any one of claims 1 to 4, characterized in that: The rounded area at the bottom of the second battery is located in the hollow area.

7. The battery pack according to any one of claims 1 to 4, characterized in that: The second battery of each battery cell includes a side surface facing the battery cells in an adjacent column, and the rounded edge of the lower portion of the shell of the second battery corresponding to the hollowed-out area of ​​the side surface is covered by the second insulating film.

8. The battery pack according to claim 7, characterized in that: Between two adjacent columns of battery cells, each battery includes a side surface facing the battery cells in the adjacent column, and a lower edge fillet of the side surface is covered by a second insulating film; In the battery cell located on the outside, the lower edge rounding of the side surface opposite to the side surface of the battery cell provided with the second insulating film is also covered by the second insulating film.

9. 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.

10. The battery pack according to claim 4, characterized in that: ρ1≥1×10 13 Ω·cm, ρ2≥7.5×10 9 Ω·cm, ρ3≥1×10 13 Ω·cm; And / or, the material of the structural adhesive is selected from one or more of polyurethane and epoxy resin; and / or, the thickness W1 of the first buffer pad is 0.5-1.5 mm; and / or, the thickness W2 of the second buffer pad is 0.5-5 mm; and / or, the thickness L1 of the first insulating film is 0.015-0.2 mm; And / or, the thickness H1 of the structural adhesive between the bottom surface of a single battery and the box body is 0.5-2.5 mm; And / or, the thickness L2 of the insulating coating is 0.1-0.3 mm; And / or, the height H2 of the second limiting strip satisfies: H1+r1≤H2≤H1+r1+3mm, where r1 is the fillet radius of the bottom of the battery; And / or, the height H3 of the hollow area satisfies: r1<H3≤H2, where r1 is the fillet radius of the bottom of the battery; And / or, 0<r2≤3.5mm.

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