Battery pack

Abstract

This utility model relates to the field of battery technology and discloses a battery pack, including: a housing; multiple battery cells arranged along the X-direction of the housing and housed within the housing, each battery cell having a cell shell covered with an insulating film, the outer surface of which has several grooves; and structural adhesive applied to both sides and the bottom surface of each battery cell along the X-direction, bonding the structural adhesive to the insulating film; the force in the X-direction at the bonded area between the insulating film and the structural adhesive satisfies the condition 120N≤(S1 / 2×γ+S2×σ)×H / L≤490N. This utility model, by reasonably setting the bonding surface area, bonding height, bonding length, shear strength, and pull-out strength between the insulating film and the structural adhesive, ensures that the force in the X-direction at the bonded area between the insulating film and the structural adhesive is within a reasonable range, thereby preventing the insulating film and structural adhesive from detaching and failing during battery pack use, and thus avoiding battery cell detachment from the battery pack housing.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a battery pack. Background Technology

[0002] New energy batteries are widely used in various fields such as transportation power supply, power storage power supply, new energy storage power supply, aerospace and military industry due to their advantages such as large capacity, high working voltage, strong charge retention capacity and long cycle life.

[0003] A battery pack typically consists of multiple battery cells, which are fixed inside the pack's casing. A battery cell generally includes a cover, casing, electrode assembly, electrode assembly end plates, bare cell insulating sheets, insulating film, and a top cover patch. The cover and casing are welded together to form a sealed space protecting the electrode assembly. The bare cell insulating sheets cover the electrode assembly, protecting it and preventing internal short circuits caused by contact with the casing. The electrode assembly end plates secure the tabs and provide space for their protection. The insulating film primarily covers the outside of the casing, providing external insulation.

[0004] Because the insulating film has low adhesion, when the insulating film on the casing is directly fixed to the battery pack body with structural adhesive, the adhesive at the insulating film often fails and falls off during mechanical vibration / impact tests of the entire pack, causing the cells to separate from the battery pack body. Utility Model Content

[0005] In view of this, the present invention provides a battery pack to solve the problem of low bonding strength between the insulating film and the structural adhesive, which leads to the detachment of battery cells inside the battery pack.

[0006] This utility model provides a battery pack, comprising:

[0007] Box;

[0008] Multiple battery cells are arranged along the X direction of the housing and housed inside the housing. Each battery cell has a battery cell housing. The outer surface of the battery cell housing is covered with an insulating film. The outer surface of the insulating film is provided with several grooves.

[0009] Structural adhesive is applied to both sides and the bottom surface of each of the battery cells in the X direction. The structural adhesive is bonded and fixed to the insulating film to fix each of the battery cells into the housing.

[0010] The bonding area between the insulating film and the structural adhesive is subject to the following force in the X direction: 120N≤(S1 / 2×γ+S2×σ)×H / L≤490N;

[0011] Wherein, S1 is the adhesive surface area between the insulating film and the structural adhesive on both sides along the X direction of the battery cell; S2 is the adhesive surface area between the insulating film and the structural adhesive on the bottom surface of the battery cell; H is the adhesive height of the structural adhesive along the Z direction on both sides of the X direction of the battery cell; L is the adhesive length between the structural adhesive and the insulating film along the Y direction of the battery cell; σ is the shear strength of the adhesive between the insulating film and the structural adhesive along the X direction of the battery cell; and γ is the pull-out strength between the insulating film and the structural adhesive along the X direction of the battery cell.

[0012] Beneficial effects: By rationally setting the bonding surface area between the insulating film and structural adhesive on both sides of the cell in the X direction, the bonding surface area between the insulating film and structural adhesive at the bottom of the cell, the shear strength and pull-out strength of the bond between the insulating film and structural adhesive, the bonding height of the structural adhesive along the Z direction on both sides of the cell in the X direction, and the bonding length between the structural adhesive and the insulating film, the force on the bonding part between the insulating film and the structural adhesive in the X direction is kept within a reasonable range. This ensures that the insulating film and structural adhesive do not detach and fail in the X direction during the use of the battery pack, thereby preventing the cells from falling off inside the battery pack.

[0013] In one optional embodiment, the thickness T1 of the structural adhesive satisfies 0.5mm≤T1≤2.0mm; and the bonding height H of the structural adhesive along the Z direction on both sides of the cell in the X direction satisfies 1.5mm≤H≤2.5mm.

[0014] Beneficial effects: By reasonably setting the thickness T1 of the structural adhesive and the bonding height H of the structural adhesive along the Z direction on both sides of the cell in the X direction, it is possible to ensure that the bonding part between the insulating film and the structural adhesive meets the requirements of the force in the X direction, while reducing the space occupied by the structural adhesive in the box, thereby improving the space utilization rate of the battery pack box.

[0015] In one optional embodiment, the battery cell is a blade battery cell. Along the X direction of the battery cell, the shear strength of the bond between the insulating film and the structural adhesive satisfies 4 MPa ≤ σ ≤ 5.5 MPa; the pull-out strength between the insulating film and the structural adhesive satisfies 3.8 MPa ≤ γ ≤ 5.0 MPa; and the force in the X direction at the bonded portion between the insulating film and the structural adhesive satisfies 120 N ≤ (S1 / 2 × γ + S2 × σ) × H / L ≤ 252 N.

[0016] Beneficial effects: By reasonably setting the values ​​of S1, S2, L, H, σ, and γ, the force in the X direction at the bonding part between the insulating film and the structural adhesive satisfies 120N≤(S1 / 2×γ+S2×σ)×H / L≤252N, ensuring that the insulating film and structural adhesive do not detach and fail in the X direction during the use of the battery pack, thereby preventing the cells inside the battery pack from falling off.

[0017] In one optional embodiment, the width W1 of the battery cell satisfies 14.5mm≤W1≤23mm; the length L1 of the battery cell satisfies 220mm≤L1≤400mm; the bonding length L satisfies 220mm≤L≤400mm; and the ratio of the bonding height H between the structural adhesive and the insulating film to the bonding length L satisfies 0.4≤100×H / L≤0.8.

[0018] Beneficial effects: By setting appropriate bonding height H and bonding length L, the connection stability between the battery cell and the housing can be determined, and the usable space inside the housing can be optimized.

[0019] In one optional embodiment, the ratio K of the surface area of ​​the insulating film facing the structural adhesive to the outline area of ​​the insulating film satisfies 1.2 ≤ K ≤ 1.4; the bonding surface area S1 between the insulating film and the structural adhesive on both sides along the X direction of the battery cell, S1 = 2 × H × L × K, satisfies 840 mm². 2 ≤S1≤2240mm 2 On the bottom surface of the battery cell, the bonding surface area S2 between the insulating film and the structural adhesive, S2 = W1 × L × K, satisfies 4320 mm². 2 ≤S2≤8120mm 2 The effective bonding surface area between the structural adhesive and the insulating film satisfies S1+S2≥5160mm². 2 .

[0020] Beneficial effects: By reasonably setting the values ​​of S1 and S2, the effective bonding surface area between the structural adhesive and the insulating film is made to satisfy S1+S2≥5160mm². 2 This ensures that the bonding area between the insulating film and the structural adhesive meets the requirements for use under X-direction force; and during the use of the battery pack, it prevents the battery cells from falling out of the box due to adhesion failure between the structural adhesive and the insulating film.

[0021] In one optional embodiment, the battery cell is a square battery cell. Along the X direction of the battery cell, the shear strength of the bond between the insulating film and the structural adhesive satisfies 4 MPa ≤ σ ≤ 5.5 MPa; the pull-out strength between the insulating film and the structural adhesive satisfies 3.8 MPa ≤ γ ≤ 5.0 MPa; and the force in the X direction at the bonded portion between the insulating film and the structural adhesive satisfies 180 N ≤ (S1 / 2 × γ + S2 × σ) × H / L ≤ 490 N.

[0022] Beneficial effects: By reasonably setting the values ​​of S1, S2, L, H, σ and γ, the force in the X direction at the bonding part between the insulating film and the structural adhesive satisfies 180N≤(S1 / 2×γ+S2×σ)×H / L≤490N, ensuring that the insulating film and structural adhesive do not detach and fail in the X direction during the use of the battery pack, thereby preventing the cells inside the battery pack from falling off.

[0023] In one optional embodiment, the width W2 of the battery cell satisfies 25mm≤W2≤65mm; the length L2 of the battery cell satisfies 150mm≤L2≤380mm; the bonding length L satisfies 120mm≤L≤250mm; and the ratio of the bonding height H between the structural adhesive and the insulating film to the bonding length L satisfies 0.65≤100×H / L≤1.2.

[0024] Beneficial effects: By setting appropriate bonding height H and bonding length L, the connection stability between the battery cell and the housing can be determined, and the usable space inside the housing can be optimized.

[0025] In one optional embodiment, the ratio K of the surface area of ​​the insulating film facing the structural adhesive to the outline area of ​​the insulating film satisfies 1.2 ≤ K ≤ 1.4; the bonding surface area S1,1 between the insulating film and the structural adhesive on both sides along the X direction of the battery cell satisfies 600 mm. 2 ≤S1≤1540mm 2 On the bottom surface of the battery cell, the bonding surface area S2 between the insulating film and the structural adhesive, S2 = W2 × L × K, satisfies 4800 mm². 2 ≤S2≤10500mm 2 The effective bonding surface area between the structural adhesive and the insulating film satisfies S1+S2≥5400mm². 2 .

[0026] Beneficial effects: By reasonably setting the values ​​of S1 and S2, the effective bonding surface area between the structural adhesive and the insulating film is made to satisfy S1+S2≥5400mm². 2 This ensures that the bonding area between the insulating film and the structural adhesive meets the requirements for use under X-direction force; and during the use of the battery pack, it prevents the battery cells from falling out of the box due to adhesion failure between the structural adhesive and the insulating film.

[0027] In one optional embodiment, the thickness T2 of the insulating film satisfies 0.15mm≤T2≤0.25mm; the depth D of the groove satisfies 60μm≤D≤150μm; and the distance W3 between two adjacent grooves satisfies 1mm≤W3≤5mm.

[0028] Beneficial effects: By providing several grooves on the outer surface of the insulating film and limiting the depth of the grooves, the contact area between the insulating film and the structural adhesive is increased, thereby improving friction and bonding strength. Further limiting the spacing between two adjacent grooves can prevent the grooves from being too dense on the surface of the insulating film, which would affect the stability of the overall structure, while ensuring the bonding strength between the insulating film and the structural adhesive.

[0029] In one optional embodiment, the depth of the groove accounts for 40%-60% of the thickness of the insulating film; the total area of ​​the plurality of grooves accounts for 30%-50% of the outer surface area of ​​the insulating film.

[0030] Beneficial effects: By limiting the ratio of the groove depth to the insulation film thickness and the ratio of the total groove area to the outer surface area of ​​the insulation film, the contact area between the insulation film and the structural adhesive can be effectively increased, thereby improving friction and bonding strength, ensuring a firm bond between the insulation film and the structural adhesive, preventing the battery cells from falling off the housing, and preventing excessive perforation of the insulation film surface due to an excessively high ratio, thus ensuring the insulation and support functions of the insulation film base. Attached Figure Description

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

[0032] Figure 1 This is a perspective view of a battery pack according to an embodiment of the present utility model;

[0033] Figure 2 This is another perspective view of a battery pack according to an embodiment of the present utility model;

[0034] Figure 3 for Figure 1 Left view of the battery pack shown;

[0035] Figure 4 for Figure 3 Enlarged diagram of A in the middle;

[0036] Figure 5 for Figure 1 A 3D view of the battery cells in the battery pack shown;

[0037] Figure 6 This is a perspective view of a battery pack according to another embodiment of the present invention;

[0038] Figure 7This is another perspective view of a battery pack according to another embodiment of the present invention;

[0039] Figure 8 for Figure 6 Left view of the battery pack shown;

[0040] Figure 9 for Figure 8 Enlarged diagram of B in the middle;

[0041] Figure 10 for Figure 6 A 3D view of the battery cells in the battery pack shown;

[0042] Figure 11 for Figure 10 Enlarged diagram of C in the middle;

[0043] Figure 12 This is an exploded view of a battery cell in a battery pack according to an embodiment of the present invention.

[0044] Explanation of reference numerals in the attached figures:

[0045] 100. Housing; 200. Battery cell; 210. Battery cell housing; 220. Insulating film; 221. Groove; 230. Cover plate; 240. Electrode group; 250. Insulating sheet; 300. Structural adhesive. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0047] The following is combined with Figures 1 to 11 The following describes embodiments of the present invention.

[0048] According to embodiments of the present invention, on the one hand, in conjunction with reference to... Figures 1 to 3A battery pack is provided, comprising: a housing 100; a plurality of battery cells 200 arranged along the X direction of the housing 100 and housed within the housing 100, each battery cell 200 having a battery cell housing 210, the outer surface of the battery cell housing 210 being covered with an insulating film 220, the outer surface of the insulating film 220 having a plurality of grooves 221; and structural adhesive 300 applied to both sides and the bottom surface of each battery cell in the X direction, the structural adhesive 300 being bonded and fixed to the insulating film 220, for fixing each battery cell 200 within the housing 100; the bonding portion between the insulating film 220 and the structural adhesive 300 is subjected to a force in the X direction satisfying 120N≤(S1 / 2×γ+S2×σ)×H / L≤490N.

[0049] In this embodiment, the X direction is the length direction of the battery pack, the Y direction is the width direction of the battery pack, and the Z direction is the height direction of the battery pack. Multiple battery cells 200 are connected in series, parallel, or in a mixed configuration via a busbar. Multiple battery cells 200 along the X direction of the housing 100 can directly form a battery pack, or they can first form battery modules, and then the battery modules form a battery pack; the battery cells 200 or battery modules are housed within the housing 100. Each battery cell 200 has a cell housing 210, and an insulating film 220 is coated on the outer surface of the cell housing 210 to achieve external insulation of the battery cell 200. Structural adhesive 300 is also coated on a portion of the outer surface of the insulating film 220, specifically on both sides along the X direction of each battery cell and on the bottom surface of the battery cell 200, i.e., one side along the Z direction of the battery cell, so that the structural adhesive 300 is bonded and fixed to the insulating film 220, thereby fixing each battery cell 200 into a whole and further fixing each battery cell 200 within the housing 100.

[0050] Further, S1 is the bonding surface area between the insulating film 220 and the structural adhesive 300 on both sides along the X direction of the battery cell; S2 is the bonding surface area between the insulating film 220 and the structural adhesive 300 on the bottom surface of the battery cell 200; H is the bonding height of the structural adhesive 300 along the Z direction on both sides of the X direction of the battery cell; L is the bonding length between the structural adhesive 300 and the insulating film 220 along the Y direction of the battery cell; σ is the shear strength of the bond between the insulating film 220 and the structural adhesive 300 along the X direction of the battery cell; γ is the pull-out strength between the insulating film 220 and the structural adhesive 300 along the X direction of the battery cell.

[0051] For example, the shear strength σ and pull-out strength γ of the bond between the insulating film 220 and the structural adhesive 300 can be measured using a universal tensile testing machine. The shear test specimens are prepared according to GB / T7124. Two shear test specimens with dimensions of 100mm × 25mm × 2mm are cut. The structural adhesive 300 is applied to one side of the insulating film 220 of both shear test specimens, with a bonding area of ​​25mm × 25mm between the insulating film 220 and the structural adhesive 300. The two shear test specimens are then fixed together. Al3003 test pieces are used for the shear test specimens, and PET film is used for the insulating film 220. The shear test specimens are repeatedly rolled with a 2kg roller at least five times and then left to stand at room temperature (23±2℃) for 24 hours. The testing then commenced. Two bonded shear specimens were fixed to fixtures. A universal tensile testing machine was used to stretch the upper end of one shear specimen and the lower end of the other at a speed of 50 mm / min. The stress was recorded, and the shear strength σ was obtained by dividing the stress on the shear specimen by the bonded surface area of ​​25 mm × 25 mm. For the pull-out test specimens, following GB / T6329, two 100 mm × 25 mm × 2 mm specimens were cut. Structural adhesive 300 was applied to one side of the insulating film 220 of both specimens, with a bonding area of ​​25 mm × 25 mm between the insulating film 220 and the structural adhesive 300. The two specimens were then fixed together. Al3003 test pieces were used for the pull-out test specimens, and PET film was used for the insulating film 220. The pull-out specimens were repeatedly rolled five or more times using a 2 kg roller and then left to stand at room temperature (23 ± 2℃) for 24 hours. The test then began. The two bonded pull-out specimens were fixed on the fixtures. A universal tensile testing machine was used to stretch the upper surface of one pull-out specimen and the lower surface of the other. The stretching speed was 50 mm / min. The values ​​were read. The pull-out strength γ was obtained by dividing the force on the pull-out specimen by the bonded surface area of ​​25 mm × 25 mm.

[0052] By reasonably setting the values ​​of S1, S2, L, H, σ, and γ, the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300 is ensured to be 120N ≤ (S1 / 2 × γ + S2 × σ) × H / L ≤ 490N. This ensures that the insulating film 220 and the structural adhesive do not detach in the X direction during battery pack use, thereby preventing the battery cells 200 from falling off inside the battery pack housing 100. If the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300 is too small, such as less than 120N, the battery cells 200 may be subjected to resonant shear force and pull-out force in the X direction during vehicle operation. After long-term vibration, this may lead to adhesion failure between the insulating film 220 and the structural adhesive 300, causing the battery cells 200 to fall off inside the battery pack housing 100. If the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300 is too large, such as greater than 490N, the adhesive layer of the structural adhesive 300 may exceed its own bearing limit, causing internal tearing of the adhesive layer. This reduces the effective bonding surface area between the insulating film 220 and the structural adhesive 300, thereby reducing the force in the X direction at the bonding area. Consequently, the battery cell 200 cannot be stably installed in the housing 100, ultimately causing the battery cell 200 to detach. Specifically, the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300 can be 120N, 160N, 180N, 200N, 240N, 252N, 280N, 320N, 360N, 400N, 440N, 490N, etc., and can be set according to actual needs without specific limitations.

[0053] In some implementations, the battery pack housing 100 can be part of the vehicle's chassis structure. For example, a portion of the housing 100 can be at least part of the vehicle's floor, or a portion of the housing 100 can be at least part of the vehicle's crossbeams and longitudinal beams.

[0054] In this embodiment of the present invention, the battery cell 200 can be a secondary battery cell, which refers to a battery cell that can be reactivated by charging after discharge and continue to be used. The battery cell 200 can be a lithium-ion battery cell, sodium-ion battery cell, sodium-lithium-ion battery cell, lithium-sulfur battery cell, magnesium-ion battery cell, nickel-metal hydride battery cell, nickel-cadmium battery cell, lead-acid battery cell, etc., and this embodiment of the present invention is not limited to this.

[0055] In some implementations, the battery cell 200 in this utility model embodiment can be a metal battery cell. Specifically, the metal battery cell may include a lithium metal secondary battery cell, a sodium metal battery cell, or a magnesium metal battery cell, etc. This utility model embodiment does not limit this.

[0056] The electrode assembly of cell 200 includes a positive electrode, a negative electrode, and an separator. During the charging and discharging process of cell 200, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, located between the positive and negative electrodes, prevents short circuits between them while allowing active ions to pass through.

[0057] In some implementations, the positive electrode can be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0058] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0059] In some implementations, the negative electrode can be a negative electrode sheet, which may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0060] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0061] In some implementations, the separator is a separator membrane. This invention does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0062] As an example, the main material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride, and ceramic.

[0063] In some implementations, the separator is a solid electrolyte. The solid electrolyte is placed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0064] In some implementations, the battery cell 200 also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This invention does not impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0065] In some implementations, the electrode assembly has tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0066] The battery cell 200 of this embodiment can be a cylindrical battery cell, a prismatic battery cell, a pouch battery, or a battery cell of other shapes. Among them, the prismatic battery cell can include a square battery cell, a blade battery cell, or other polyprismatic battery cells, such as a hexagonal prismatic battery cell or an octagonal prismatic battery cell, and this embodiment of the present invention is not limited thereto.

[0067] See also Figure 4 In one embodiment, the thickness T1 of the structural adhesive 300 satisfies 0.5mm≤T1≤2.0mm; on both sides of the cell in the X direction, the bonding height H of the structural adhesive 300 along the Z direction satisfies 1.5mm≤H≤2.5mm.

[0068] In this embodiment, the thickness T1 of the structural adhesive 300 can specifically be 0.5mm, 0.7mm, 0.9mm, 1.1mm, 1.3mm, 1.5mm, 1.7mm, 1.9mm, 2.0mm, etc., and can be set according to requirements. If the thickness T1 of the structural adhesive 300 is too small, such as less than 0.5mm, the structural adhesive 300 may not be effectively bonded to the insulating film 220 due to uneven coating, resulting in insufficient force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300, thus preventing the battery cell 200 from being properly fixed inside the housing 100. If the thickness T1 of the structural adhesive 300 is too large, such as greater than 2.0mm, it will increase the cost of using the structural adhesive 300; moreover, a thicker structural adhesive 300 will occupy internal space in the housing 100, reducing the utilization rate of the internal space of the housing 100.

[0069] The bonding height H of the structural adhesive 300 along the Z direction on both sides of the battery cell in the X direction can be 1.5mm, 1.7mm, 1.9mm, 2.0mm, 2.1mm, 2.3mm, 2.5mm, etc., and can be set according to requirements. Specifically, the bonding height H of the structural adhesive 300 along the Z direction on both sides of the battery cell 200 can be the height to which the structural adhesive 300 covers the two sides of the battery cell 200 upwards, that is, the distance between the bottom end face of the battery cell 200 and the top end face of the structural adhesive 300. If the bonding height H is too small, such as less than 1.5mm, the bonding surface area between the structural adhesive 300 and the insulating film 220 may be insufficient, resulting in low force between the structural adhesive 300 and the insulating film 220, thus preventing the battery cell 200 from being properly fixed inside the housing 100. If the bonding height H is too large, such as greater than 2.5mm, it will also increase the cost of using the structural adhesive 300 and occupy internal space in the housing 100, reducing the utilization rate of the internal space of the housing 100. By reasonably setting the thickness T1 of the structural adhesive 300 and the bonding height H of the structural adhesive 300 along the Z direction on both sides of the cell in the X direction, it is possible to ensure that the bonding part between the insulating film 220 and the structural adhesive 300 meets the requirements of the force in the X direction, while reducing the space occupied by the structural adhesive 300 in the housing 100, thereby improving the space utilization rate of the battery pack housing 100.

[0070] See also Figure 5In one embodiment, the battery cell 200 is a blade battery cell. Along the X direction of the battery cell, the shear strength of the bond between the insulating film 220 and the structural adhesive 300 satisfies 4 MPa ≤ σ ≤ 5.5 MPa; the pull-out strength between the insulating film 220 and the structural adhesive 300 satisfies 3.8 MPa ≤ γ ≤ 5.0 MPa; the force in the X direction at the bonded portion between the insulating film 220 and the structural adhesive 300 satisfies 120 N ≤ (S1 / 2 × γ + S2 × σ) × H / L ≤ 252 N.

[0071] In this embodiment, the battery cell 200 is a blade battery cell. The shear strength σ of the bond between the insulating film 220 and the structural adhesive 300 can specifically be 4 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa, 5 MPa, 5.2 MPa, 5.5 MPa, etc.; the pull-out strength γ between the insulating film 220 and the structural adhesive 300 can specifically be 3.8 MPa, 4.0 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa, 5.0 MPa, etc., and can be set according to the usage requirements. By reasonably setting the values ​​of S1, S2, L, H, σ, and γ, the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300 is ensured to be 120N ≤ (S1 / 2 × γ + S2 × σ) × H / L ≤ 252N. This ensures that the insulating film 220 and the structural adhesive do not detach in the X direction during battery pack use, thereby preventing the battery cells 200 from falling off inside the battery pack housing 100. If the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300 is too small, such as less than 120N, the battery cells 200 may be subjected to resonant shear force and pull-out force in the X direction during vehicle operation. After long-term vibration, this could lead to adhesion failure between the insulating film 220 and the structural adhesive 300, causing the battery cells 200 to fall off inside the battery pack housing 100. If the bonding area between the insulating film 220 and the structural adhesive 300 is subjected to excessive force in the X direction, such as greater than 252N, the adhesive layer of the structural adhesive 300 may exceed its own bearing limit, causing internal tearing of the adhesive layer. This reduces the effective bonding surface area between the insulating film 220 and the structural adhesive 300, thereby reducing the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300. Consequently, the battery cell 200 cannot be stably installed in the housing 100, ultimately causing the battery cell 200 to detach.

[0072] In one embodiment, the width W1 of the battery cell 200 satisfies 14.5mm≤W1≤23mm; the length L1 of the battery cell 200 satisfies 220mm≤L1≤400mm; the bonding length L satisfies 220mm≤L≤400mm; and the ratio of the bonding height H between the structural adhesive 300 and the insulating film 220 to the bonding length L satisfies 0.4≤100×H / L≤0.8.

[0073] In this embodiment, the width W1 of the battery cell 200 can specifically be 14.5mm, 16mm, 18mm, 20mm, 21mm, 23mm, etc., and the length L1 of the battery cell 200 can specifically be 220mm, 240mm, 260mm, 280mm, 300mm, 320mm, 340mm, 360mm, 380mm, 400mm, etc., which can be set according to actual usage requirements. It can be understood that the width W1 of the battery cell 200 represents the sum of the width of the battery cell housing 210 and the thickness of the insulating film 220. The bonding length L between the structural adhesive 300 and the insulating film 220 along the Y direction of the battery cell is the same as the length L1 of the battery cell 200, that is, the bottom of the battery cell 200 is fully coated with structural adhesive 300 along the Y direction to ensure that the stress generated by thermal expansion during charging and discharging is evenly distributed, avoiding bonding failure caused by local stress concentration. Further, the ratio of the bonding height H to the bonding length L is determined based on the bonding height H between the structural adhesive 300 and the insulating film 220, and the bonding length L between the structural adhesive 300 and the insulating film 220 in the Y direction of the battery cell. This ratio should satisfy 0.4 ≤ 100 × H / L ≤ 0.8. If the ratio is too small, such as less than 0.4, the bonding strength between the structural adhesive 300 and the insulating film 220 may be insufficient, causing the battery cell 200 to detach from the housing 100. If the ratio is too large, such as greater than 0.8, it may increase the amount of structural adhesive 300 used, thereby occupying too much usable space within the housing 100 and affecting the space utilization rate of the housing 100. By setting appropriate bonding height H and bonding length L, the connection stability between the battery cell 200 and the housing 100 can be determined, and the usable space inside the housing 100 can be optimized.

[0074] In one embodiment, the ratio K of the surface area of ​​the insulating film 220 facing the structural adhesive 300 to the outline area of ​​the insulating film 220 satisfies 1.2≤K≤1.4; the bonding surface area S1 between the insulating film 220 and the structural adhesive 300 along both sides of the cell X direction, S1=2×H×L×K, satisfies 840mm². 2 ≤S1≤2240mm 2 On the bottom surface of the battery cell 200, the bonding surface area S2 between the insulating film 220 and the structural adhesive 300, S2 = W1 × L × K, satisfies 4320 mm². 2 ≤S2≤8120mm 2 The effective bonding surface area between structural adhesive 300 and insulating film 220 satisfies S1+S2≥5160mm². 2 .

[0075] In this embodiment, the ratio K of the surface area of ​​the insulating film 220 facing the structural adhesive 300 to the outline area of ​​the insulating film 220 can specifically be 1.2, 1.3, 1.4, etc.; the bonding surface area S1 between the insulating film 220 and the structural adhesive 300 on both sides along the X direction of the battery cell can specifically be 840 mm². 2 1000mm 2 1200mm 2 1400mm 2 1600mm 2 1800mm 2 2000mm 2 2240mm 2 The bonding surface area S2 between the bottom insulating film 220 of the battery cell 200 and the structural adhesive 300 can specifically be 4320 mm². 2 4800mm 2 5200mm 2 5600mm 2 6000mm 2 6400mm 2 6800mm 2 7200mm 2 7600mm 2 8000mm 2 8120mm 2 The specific settings can be customized according to actual usage needs.

[0076] Furthermore, since the surface of the insulating film 220 facing the structural adhesive 300 has several grooves 221, the surface area of ​​the insulating film 220 is larger than its outline area. Specifically, surface area = K × outline area, where the outline area is equal to the length of the insulating film 220 multiplied by its width. When the insulating film 220 wraps the battery cell 200, the length and width of the insulating film 220 located on a certain side of the battery cell 200 are equal to the length and width of that side of the battery cell 200. In other words, the length and width of the insulating film 220 can be directly measured. K is a coefficient, determined by constructing the shape of the insulating film using a three-dimensional simulation model and calculating its outline area and adhesive surface area.

[0077] If S1 is too small, such as less than 840mm 2 This indicates that the side bonding surface area of ​​the battery cell 200 is too small, and the structural adhesive 300 is prone to detachment due to localized stress concentration, causing the battery cell 200 to separate from the housing 100. If S1 is too large, such as greater than 2240mm... 2This will result in excessive use of structural adhesive 300, increasing manufacturing costs and the space it occupies within the enclosure 100, leading to low utilization of the internal space. If S2 is too small, such as less than 4320mm... 2 This indicates that the bonding surface area of ​​the bottom of the battery cell 200 is too small, which will also cause delamination due to localized stress concentration in the structural adhesive 300, leading to the separation of the battery cell 200 from the casing 100. If S2 is too large, such as greater than 8120mm... 2 This will also increase the amount of structural adhesive 300 used, thereby increasing the space occupied by structural adhesive 300 inside the box 100, resulting in low utilization of the internal space of the box 100.

[0078] By reasonably setting the values ​​of S1 and S2, the effective bonding surface area between the structural adhesive 300 and the insulating film 220 is made to satisfy S1+S2≥5160mm². 2 This ensures that the bonding area between the insulating film 220 and the structural adhesive 300 is subjected to force in the X direction that meets the usage requirements; during the use of the battery pack, it prevents the battery cell 200 from falling off the casing 100 due to bonding failure between the structural adhesive 300 and the insulating film 220.

[0079] To verify the aforementioned blade battery cell, vibration tests were conducted on the blade battery cell according to the testing standard "Safety Requirements for Power Batteries for Electric Vehicles" (GB38031-2020), and a whole-pack simulation analysis was performed to verify the failure at the 220mm insulating film. The test results are shown in Table 1.

[0080] Table 1

[0081]

[0082]

[0083] As can be seen from Table 1, when H and (S1 / 2×γ+S2×σ)×H / L are small, a tear was found at the 220 position of the insulating film after the vibration test; when H / L is large, although no tear was found at the 220 position of the insulating film, the excessive application of structural adhesive 300 increased the manufacturing cost and the weight of the whole package.

[0084] See also Figures 6 to 12 In one embodiment, the battery cell 200 is a square battery cell. Along the X direction of the battery cell, the shear strength of the bond between the insulating film 220 and the structural adhesive 300 satisfies 4 MPa ≤ σ ≤ 5.5 MPa; the pull-out strength between the insulating film 220 and the structural adhesive 300 satisfies 3.8 MPa ≤ γ ≤ 5.0 MPa; the force in the X direction at the bonded portion between the insulating film 220 and the structural adhesive 300 satisfies 180 N ≤ (S1 / 2 × γ + S2 × σ) × H / L ≤ 490 N.

[0085] In this embodiment, the square battery cell includes a battery cell housing 210, an insulating film 220, a cover plate 230, an electrode assembly 240, and an insulating sheet 250. The cover plate 230 and the battery cell housing 210 are welded and fixed together to form a sealed space protecting the electrode assembly 240. The electrode assembly 240 is covered with an insulating sheet 250 to prevent the electrode assembly from contacting the battery cell housing 210 and causing an internal short circuit in the battery cell 200; the insulating film 220 covers the outside of the battery cell housing 210 to achieve external insulation of the battery cell housing 210. The shear strength σ of the bond between the insulating film 220 and the structural adhesive 300 can be 4 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa, 5 MPa, 5.2 MPa, 5.5 MPa, etc.; the pull-out strength γ between the insulating film 220 and the structural adhesive 300 can be 3.8 MPa, 4 MPa, 4.2 MPa, 4.4 MPa, 4.6 MPa, 4.8 MPa, 5 MPa, etc., and can be set according to the usage requirements. By reasonably setting the values ​​of S1, S2, L, H, σ, and γ, the force in the X direction on the bonded part between the insulating film 220 and the structural adhesive 300 satisfies 180N≤(S1 / 2×γ+S2×σ)×H / L≤490N, ensuring that the insulating film 220 and the structural adhesive do not detach and fail in the X direction during the use of the battery pack, thereby preventing the cells 200 inside the battery pack housing 100 from falling off. If the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300 is too small, such as less than 180N, the battery cell 200 may be subjected to resonant shear force and pull-out force in the X direction during vehicle operation. Prolonged vibration may cause the bond between the insulating film 220 and the structural adhesive 300 to fail, leading to the battery cell 200 detaching from the battery pack housing 100. If the force in the X direction at the bonding area between the insulating film 220 and the structural adhesive 300 is too large, such as greater than 490N, the adhesive layer of the structural adhesive 300 may exceed its own bearing limit, causing internal tearing. This reduces the effective bonding surface area between the insulating film 220 and the structural adhesive 300, further reducing the force in the X direction at the bonding area. Consequently, the battery cell 200 cannot be stably installed in the housing 100, ultimately causing the battery cell 200 to detach.

[0086] In one embodiment, the width W2 of the battery cell 200 satisfies 25mm≤W2≤65mm; the length L2 of the battery cell 200 satisfies 150mm≤L2≤380mm; the bonding length L satisfies 120mm≤L≤250mm; and the ratio of the bonding height H between the structural adhesive 300 and the insulating film 220 to the bonding length L satisfies 0.65≤100×H / L≤1.2.

[0087] In this embodiment, the width W2 of the battery cell 200 can specifically be 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, etc., and the length L2 of the battery cell 200 can specifically be 150mm, 180mm, 210mm, 240mm, 270mm, 300mm, 330mm, 360mm, 380mm, etc., which can be set according to actual usage requirements. It can be understood that the width W2 of the battery cell 200 represents the sum of the width of the battery cell housing 210 and the thickness of the insulating film 220. The bonding length L between the structural adhesive 300 and the insulating film 220 along the Y direction of the battery cell can be 120mm, 150mm, 180mm, 210mm, 240mm, 250mm, etc., and L is less than L2. This ensures that there is a sufficient bonding range between the structural adhesive 300 and the insulating film 220 in the Y direction of the battery cell 200, providing stable fixation and protection for the battery cell 200, avoiding detachment or loosening due to excessive bonding length, and at the same time avoiding excessive use of structural adhesive 300 to avoid occupying too much usable space in the housing 100.

[0088] Further, the ratio of the bonding height H to the bonding length L is determined based on the bonding height H between the structural adhesive 300 and the insulating film 220, and the bonding length L between the structural adhesive 300 and the insulating film 220 in the Y direction of the battery cell. This ratio should satisfy 0.65 ≤ 100 × H / L ≤ 1.2. If the ratio is too small, such as less than 0.65, the bonding strength between the structural adhesive 300 and the insulating film 220 may be insufficient, causing the battery cell 200 to detach from the housing 100. If the ratio is too large, such as greater than 1.2, it may increase the amount of structural adhesive 300 used, thereby occupying too much usable space within the housing 100 and affecting the space utilization rate of the housing 100. By setting appropriate bonding height H and bonding length L, the connection stability between the battery cell 200 and the housing 100 can be determined, and the usable space inside the housing 100 can be optimized.

[0089] In one embodiment, the ratio K of the surface area of ​​the insulating film 220 facing the structural adhesive 300 to the outline area of ​​the insulating film 220 satisfies 1.2≤K≤1.4; the bonding surface area S1 between the insulating film 220 and the structural adhesive 300 along both sides of the cell X direction, S1=2×H×L×K, satisfies 600mm. 2 ≤S1≤1540mm 2 On the bottom surface of the battery cell 200, the bonding surface area S2 between the insulating film 220 and the structural adhesive 300, S2 = W2 × L × K, satisfies 4800 mm². 2 ≤S2≤10500mm 2 The effective bonding surface area between structural adhesive 300 and insulating film 220 satisfies S1+S2≥5400mm².2 .

[0090] In this embodiment, the bonding surface area S1 between the insulating films 220 on both sides of the cell along the X direction and the structural adhesive 300 can specifically be 600 mm². 2 700mm 2 800mm 2 900mm 2 1000mm 2 1100mm 2 1200mm 2 1300mm 2 1400mm 2 1500mm 2 1540mm 2 The bonding surface area S2 between the bottom insulating film 220 of the battery cell 200 and the structural adhesive 300 can specifically be 4800 mm². 2 5200mm 2 5600mm 2 6000mm 2 6400mm 2 6800mm 2 7200mm 2 7600mm 2 8000mm 2 8400mm 2 8800mm 2 9200mm 2 9600mm 2 10000mm 2 10500mm 2 The specific settings can be customized according to actual usage needs.

[0091] If S1 is too small, such as less than 600mm 2 This indicates that the side bonding surface area of ​​the battery cell 200 is too small, and the structural adhesive 300 is prone to detachment due to localized stress concentration, causing the battery cell 200 to separate from the housing 100. If S1 is too large, such as greater than 1540mm... 2 This will result in excessive use of structural adhesive 300, increasing manufacturing costs and the space it occupies within the enclosure 100, leading to low utilization of the internal space. If S2 is too small, such as less than 4800mm... 2 This indicates that the bonding surface area of ​​the bottom of the battery cell 200 is too small, which will also cause delamination due to localized stress concentration in the structural adhesive 300, leading to the separation of the battery cell 200 from the casing 100. If S2 is too large, such as greater than 10500mm... 2This will also increase the amount of structural adhesive 300 used, thereby increasing the space occupied by structural adhesive 300 inside the box 100, resulting in low utilization of the internal space of the box 100.

[0092] By reasonably setting the values ​​of S1 and S2, the effective bonding surface area between the structural adhesive 300 and the insulating film 220 is made to satisfy S1+S2≥5400mm². 2 This ensures that the bonding area between the insulating film 220 and the structural adhesive 300 is subjected to force in the X direction that meets the usage requirements; during the use of the battery pack, it prevents the battery cell 200 from falling off the casing 100 due to bonding failure between the structural adhesive 300 and the insulating film 220.

[0093] To verify the aforementioned square battery cells, vibration tests were conducted on the square cells according to the testing standard "Safety Requirements for Power Batteries for Electric Vehicles" (GB38031-2020), and a whole-pack simulation analysis was performed to verify the failure status at the 220mm insulating film. The test results are shown in Table 2.

[0094] Table 2

[0095]

[0096]

[0097] As can be seen from Table 2, when H and (S1 / 2×γ+S2×σ)×H / L are small, a tear was found at the insulation film 220 after the vibration test; when H / L is large, although no tear was found at the insulation film 220, the excessive application of structural adhesive 300 increased the manufacturing cost and the weight of the whole package.

[0098] In one embodiment, the thickness T2 of the insulating film 220 satisfies 0.15mm ≤ T2 ≤ 0.25mm; the depth D of the groove 221 satisfies 60μm ≤ D ≤ 150μm; and the spacing W3 between two adjacent grooves 221 satisfies 1mm ≤ W3 ≤ 5mm. Further, the depth of the groove 221 accounts for 40%-60% of the thickness of the insulating film 220; and the total area of ​​the grooves 221 accounts for 30%-50% of the outer surface area of ​​the insulating film 220.

[0099] In this embodiment, the thickness T2 of the insulating film 220 can specifically be 0.15mm, 0.16mm, 0.17mm, 0.18mm, 0.19mm, 0.20mm, 0.21mm, 0.22mm, 0.23mm, 0.24mm, 0.25mm, etc. By reasonably setting the thickness of the insulating film 220, the insulating performance of the insulating film 220 can be guaranteed. By providing a plurality of grooves 221 on the outer surface of the insulating film 220, the contact area between the insulating film 220 and the structural adhesive 300 is increased, thereby improving the friction and bonding strength.

[0100] The depth D of the groove 221 can be 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, etc., and the spacing W3 between two adjacent grooves 221 can be 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc., which can be set according to actual usage requirements. By setting an appropriate groove depth 221, the strength of the insulating film 220 can be avoided from decreasing due to excessive groove depth. By setting an appropriate distance between two adjacent grooves 221, the grooves 221 can be prevented from being too dense on the surface of the insulating film 220, thus affecting the stability of the overall structure, while ensuring the bonding strength between the insulating film 220 and the structural adhesive 300.

[0101] By setting the depth of the grooves 221 to be 40%-60% of the thickness of the insulating film 220, the contact area between the insulating film 220 and the structural adhesive 300 can be effectively increased, thereby improving friction and bonding strength, ensuring a firm bond between the insulating film 220 and the structural adhesive 300, and preventing the battery cell 200 from detaching from the housing 100. By setting the total area of ​​several grooves 221 to be 30%-50% of the outer surface area of ​​the insulating film 220, it is ensured that the grooves 221 effectively increase the bonding surface area between the insulating film 220 and the structural adhesive 300, while avoiding excessive perforation of the insulating film 220 surface due to an excessive proportion, thus guaranteeing the basic insulation and support functions of the insulating film 220.

[0102] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A battery pack, characterized in that, include: Box; Multiple battery cells are arranged along the X direction of the housing and housed inside the housing. Each battery cell has a battery cell housing. The outer surface of the battery cell housing is covered with an insulating film. The outer surface of the insulating film is provided with several grooves. Structural adhesive is applied to both sides and the bottom surface of each of the battery cells in the X direction. The structural adhesive is bonded and fixed to the insulating film to fix each of the battery cells into the housing. The bonding area between the insulating film and the structural adhesive is subjected to a force in the X direction, satisfying 120N≤(S1 / 2×γ+S2×σ)×H / L≤490N; Wherein, S1 is the adhesive surface area between the insulating film and the structural adhesive on both sides along the X direction of the battery cell; S2 is the adhesive surface area between the insulating film and the structural adhesive on the bottom surface of the battery cell; H is the adhesive height of the structural adhesive along the Z direction on both sides of the X direction of the battery cell; L is the adhesive length between the structural adhesive and the insulating film along the Y direction of the battery cell; σ is the shear strength of the adhesive between the insulating film and the structural adhesive along the X direction of the battery cell; and γ is the pull-out strength between the insulating film and the structural adhesive along the X direction of the battery cell.

2. The battery pack according to claim 1, characterized in that, The thickness T1 of the structural adhesive satisfies 0.5mm≤T1≤2.0mm; the bonding height H of the structural adhesive along the Z direction on both sides of the cell in the X direction satisfies 1.5mm≤H≤2.5mm.

3. The battery pack according to claim 1, characterized in that, The battery cell is a blade battery cell. Along the X direction of the battery cell, the shear strength of the bond between the insulating film and the structural adhesive satisfies 4 MPa ≤ σ ≤ 5.5 MPa; the pull-out strength between the insulating film and the structural adhesive satisfies 3.8 MPa ≤ γ ≤ 5.0 MPa; the force on the bonded portion between the insulating film and the structural adhesive in the X direction satisfies 120 N ≤ (S1 / 2 × γ + S2 × σ) × H / L ≤ 252 N.

4. The battery pack according to claim 3, characterized in that, The width W1 of the battery cell satisfies 14.5mm≤W1≤23mm; the length L1 of the battery cell satisfies 220mm≤L1≤400mm; the bonding length L satisfies 220mm≤L≤400mm; and the ratio of the bonding height H between the structural adhesive and the insulating film to the bonding length L satisfies 0.4≤100×H / L≤0.

8.

5. The battery pack according to claim 3, characterized in that, The ratio K of the surface area of ​​the insulating film facing the structural adhesive to the outline area of ​​the insulating film satisfies 1.2 ≤ K ≤ 1.4; the bonding surface area S1 between the insulating film and the structural adhesive on both sides along the X direction of the battery cell, S1 = 2 × H × L × K, satisfies 840 mm². 2 ≤S1≤2240mm 2 On the bottom surface of the battery cell, the bonding surface area S2 between the insulating film and the structural adhesive, S2 = W1 × L × K, satisfies 4320 mm². 2 ≤S2≤8120mm 2 The effective bonding surface area between the structural adhesive and the insulating film satisfies S1+S2≥5160mm². 2 .

6. The battery pack according to claim 1, characterized in that, The battery cell is a square battery cell. Along the X direction of the battery cell, the shear strength of the bond between the insulating film and the structural adhesive satisfies 4 MPa ≤ σ ≤ 5.5 MPa; the pull-out strength between the insulating film and the structural adhesive satisfies 3.8 MPa ≤ γ ≤ 5.0 MPa; the force on the bonded portion between the insulating film and the structural adhesive in the X direction satisfies 180 N ≤ (S1 / 2 × γ + S2 × σ) × H / L ≤ 490 N.

7. The battery pack according to claim 6, characterized in that, The width W2 of the battery cell satisfies 25mm≤W2≤65mm; the length L2 of the battery cell satisfies 150mm≤L2≤380mm; the bonding length L satisfies 120mm≤L≤250mm; and the ratio of the bonding height H between the structural adhesive and the insulating film to the bonding length L satisfies 0.65≤100×H / L≤1.

2.

8. The battery pack according to claim 6, characterized in that, The ratio K of the surface area of ​​the insulating film facing the structural adhesive to the outline area of ​​the insulating film satisfies 1.2 ≤ K ≤ 1.4; the bonding surface area S1 between the insulating film and the structural adhesive on both sides along the X direction of the battery cell, S1 = 2 × H × L × K, satisfies 600 mm². 2 ≤S1≤1540mm 2 On the bottom surface of the battery cell, the bonding surface area S2 between the insulating film and the structural adhesive, S2 = W2 × L × K, satisfies 4800 mm². 2 ≤S2≤10500mm 2 The effective bonding surface area between the structural adhesive and the insulating film satisfies S1+S2≥5400mm². 2 .

9. The battery pack according to any one of claims 1-8, characterized in that, The thickness T2 of the insulating film satisfies 0.15mm≤T2≤0.25mm; the depth D of the groove satisfies 60μm≤D≤150μm; and the distance W3 between two adjacent grooves satisfies 1mm≤W3≤5mm.

10. The battery pack according to claim 9, characterized in that, The depth of the groove accounts for 40%-60% of the thickness of the insulating film; the total area of ​​the grooves accounts for 30%-50% of the outer surface area of ​​the insulating film.

Images