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, the outer surface of which is covered with an insulating film, the outer surface of which is wavy; structural adhesive applied to both sides and the bottom surface of each battery cell along the X direction, the structural adhesive being bonded and fixed to the insulating film; the bonded portion between the insulating film and the structural adhesive is subjected to a force in the Y direction satisfying 2.6 × 10 6 N·mm≤(S1+S2)σL≤16×10 6 N·mm. This utility model, by reasonably setting the bonding surface area, bonding length, and shear strength between the insulating film and structural adhesive on both sides and the bottom of the battery cell in the X direction, ensures that the bonding part between the insulating film and structural adhesive is subjected to a reasonable force in the Y direction, thereby ensuring that the insulating film and structural adhesive do not detach and fail in the Y direction during the use of the battery pack, and preventing the battery cells from falling off inside the battery pack.

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 within the housing. Each battery cell has a battery cell housing, and the outer surface of the battery cell housing is covered with an insulating film. The outer surface of the insulating film is wavy.

[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 a force in the Y direction satisfying 2.6 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤16×10 6 N·mm;

[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; 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 adhesion between the insulating film and the structural adhesive along the Y direction of the battery cell.

[0012] Beneficial effects: By reasonably 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 bonding length between the structural adhesive at the bottom of the cell and the insulating film, and the shear strength of the bond between the insulating film and the structural adhesive, the force in the Y direction on the bonding part between the insulating film and the structural adhesive is kept within a reasonable range. This ensures that the insulating film and structural adhesive do not detach and fail in the Y 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 battery cell is a blade battery cell. Along the Y-direction of the battery cell, the shear strength of the bond between the insulating film and the structural adhesive satisfies 3.5 MPa ≤ σ ≤ 4.8 MPa; the force exerted on the bonded portion between the insulating film and the structural adhesive in the Y-direction satisfies 5.2 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤16×10 6 N·mm.

[0014] Beneficial effects: By reasonably setting the values ​​of S1, S2, L, and σ, the force in the Y direction at the bonding area between the insulating film and the structural adhesive satisfies 5.2 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤16×10 6 N·mm, to ensure that the insulating film and structural adhesive do not detach and fail in the Y direction during use, thereby preventing the cells from falling out of the battery pack.

[0015] 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≤4mm.

[0016] 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 Y direction, while reducing the space occupied by the structural adhesive in the box, thereby improving the space utilization rate of the battery pack box.

[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 250mm≤L1≤430mm; and the bonding length L satisfies 250mm≤L≤430mm.

[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 1.3 ≤ K ≤ 1.6; 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 1040 mm². 2 ≤S1≤3200mm 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 4550 mm². 2 ≤S2≤9600mm 2 .

[0020] Beneficial effects: By reasonably setting the values ​​of S1 and S2, the force in the Y direction at the bonding area between the insulating film and the structural adhesive meets the usage requirements; during the use of the battery pack, it prevents the battery cells from falling off the box due to bonding failure between the structural adhesive and the insulating film.

[0021] In one optional embodiment, the battery cell is a square battery cell, and along the Y-direction of the battery cell, the shear strength of the bond between the insulating film and the structural adhesive satisfies 3.5 MPa ≤ σ ≤ 4.8 MPa; the force exerted on the bonded portion between the insulating film and the structural adhesive in the Y-direction satisfies 2.6 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤10.4×10 6 N·mm.

[0022] Beneficial effects: By reasonably setting the values ​​of S1, S2, L, and σ, the force in the Y direction at the bonding area between the insulating film and the structural adhesive satisfies 2.6 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤10.4×10 6 N·mm, to ensure that the insulating film and structural adhesive do not detach and fail in the Y direction during use, thereby preventing the cells from falling out of the battery pack.

[0023] 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≤3.5mm.

[0024] 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 Y direction, while reducing the space occupied by the structural adhesive in the box, thereby improving the space utilization rate of the battery pack box.

[0025] 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; and the bonding length L satisfies 120mm≤L≤260mm.

[0026] 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.

[0027] 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 1.3 ≤ K ≤ 1.6; 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 780 mm². 2 ≤S1≤1920mm 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 4550 mm². 2 ≤S2≤9600mm 2 .

[0028] Beneficial effects: By reasonably setting the values ​​of S1 and S2, the force in the Y direction at the bonding area between the insulating film and the structural adhesive meets the usage requirements; during the use of the battery pack, it prevents the battery cells from falling off the box due to bonding failure between the structural adhesive and the insulating film.

[0029] In one optional embodiment, the wave amplitude of the insulating film is I, satisfying 15μm≤I≤40μm, the spacing between adjacent wave peaks is J, satisfying 120μm≤J≤200μm; the thickness of the insulating film is T2, satisfying 0.1mm≤T2≤0.15mm.

[0030] Beneficial effects: By setting appropriate wave amplitude I and spacing J between adjacent wave crests, the contact area between insulating film 220 and structural adhesive 300 can be increased, thereby improving friction and bonding strength, ensuring a firm bond between insulating film 220 and structural adhesive 300, and preventing the battery cell from falling off the housing. 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 7 This 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 diagram;

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

[0042] Figure 11 This is an exploded view of a battery cell in a battery pack according to an embodiment of the present invention.

[0043] Explanation of reference numerals in the attached figures:

[0044] 100. Housing; 200. Battery cell; 210. Battery cell housing; 220. Insulating film; 230. Cover plate; 240. Electrode assembly; 250. Insulating sheet; 300. Structural adhesive. Detailed Implementation

[0045] 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.

[0046] The following is combined Figures 1 to 11 The following describes embodiments of the present invention.

[0047] According to embodiments of the present invention, on the one hand, in conjunction with reference to... Figures 1 to 3 A 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 cell housing 210, the outer surface of which is covered with an insulating film 220, the outer surface of which is corrugated; 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 to secure each battery cell 200 within the housing 100; the bonded portion between the insulating film 220 and the structural adhesive 300 is subjected to a force in the Y direction satisfying 2.6 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤16×10 6 N·mm.

[0048] 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.

[0049] Furthermore, 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; 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 Y direction of the battery cell.

[0050] For example, the shear strength σ 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 test was then conducted. The two bonded shear specimens were fixed on the fixtures and stretched at a speed of 50 mm / min. The shear strength σ was obtained by dividing the force on the shear specimen by the bonded surface area of ​​25 mm × 25 mm.

[0051] By appropriately setting the values ​​of S1, S2, L, and σ, the force in the Y direction at the bonding area between the insulating film 220 and the structural adhesive 300 is made to satisfy 2.6 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤16×10 6N·mm, to ensure that the insulating film 220 does not detach from the structural adhesive in the Y 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 Y direction at the bonding area between the insulating film 220 and the structural adhesive 300 is too small, such as less than 2.6 × 10 N·mm, it will cause the battery pack to detach. 6 If the force is too high (N·mm), the cell 200 may be subjected to resonant shear force in the Y direction during vehicle operation. Prolonged vibration could lead to adhesion failure between the insulating film 220 and the structural adhesive 300, causing the cell 200 to detach from the battery pack housing 100. If the force on the bonded area between the insulating film 220 and the structural adhesive 300 is too high in the Y direction, such as greater than 16 × 10⁻⁶ N·mm, it could cause the cell 200 to detach. 6 If the force exceeds the allowable limit (N·mm), the adhesive layer of structural adhesive 300 may exceed its own bearing capacity, leading to internal tearing. This reduces the effective bonding surface area between the insulating film 220 and the structural adhesive 300, consequently decreasing the force in the Y direction at the bonding area. Consequently, the battery cell 200 cannot be stably installed within the housing 100, ultimately causing it to detach. Specifically, the force in the Y direction at the bonding area between the insulating film 220 and the structural adhesive 300 can be 2.6 × 10⁻⁶ N·mm. 6 N·mm, 3×10 6 N·mm, 4×10 6 N·mm, 5.2×10 6 N·mm, 6×10 6 N·mm, 7×10 6 N·mm, 8×10 6 N·mm, 9×10 6 N·mm, 10.4×10 6 N·mm, 11×10 6 N·mm, 12×10 6 N·mm, 13×10 6 N·mm, 14×10 6 N·mm, 15×10 6 N·mm, 16×10 6 N·mm, etc., can be set according to actual needs, without specific restrictions.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] In one embodiment, the battery cell 200 is a blade battery cell. Along the Y-direction of the battery cell, the shear strength of the bond between the insulating film 220 and the structural adhesive 300 satisfies 3.5 MPa ≤ σ ≤ 4.8 MPa; the bonded portion between the insulating film 220 and the structural adhesive 300 subjected to a force in the Y-direction satisfies 5.2 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤16×10 6 N·mm.

[0067] 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 3.5 MPa, 3.7 MPa, 3.9 MPa, 4.1 MPa, 4.3 MPa, 4.5 MPa, 4.7 MPa, 4.8 MPa, etc., which can be set according to the usage requirements. By reasonably setting the values ​​of S1, S2, L, and σ, the force in the Y direction at the bonding part between the insulating film 220 and the structural adhesive 300 satisfies 5.2 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤16×10 6 N·mm, to ensure that the insulating film 220 does not detach from the structural adhesive in the Y 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 Y direction at the bonding area between the insulating film 220 and the structural adhesive 300 is too small, such as less than 5.2 × 10 N·mm, it will cause the battery pack to detach. 6 If the force is too high (N·mm), the cell 200 may be subjected to resonant shear force in the Y direction during vehicle operation. Prolonged vibration could lead to adhesion failure between the insulating film 220 and the structural adhesive 300, causing the cell 200 to detach from the battery pack housing 100. If the force on the bonded area between the insulating film 220 and the structural adhesive 300 is too high in the Y direction, such as greater than 16 × 10⁻⁶ N·mm, it could cause the cell 200 to detach. 6If the force exceeds N·mm, the adhesive layer of structural adhesive 300 may exceed its own bearing limit, causing internal tearing of the adhesive layer. This reduces the effective bonding surface area between insulating film 220 and structural adhesive 300, thereby reducing the force in the Y direction at the bonding area between insulating film 220 and structural adhesive 300. Consequently, the battery cell 200 cannot be stably installed in the housing 100, ultimately causing the battery cell 200 to detach.

[0068] 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≤4mm.

[0069] 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 Y 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.

[0070] 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, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 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 in the X direction can be the height to which the structural adhesive 300 covers the two sides of the battery cell 200, that is, the distance from the bottom end face of the battery cell 200 to 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 4mm, 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 Y 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.

[0071] See also Figure 5 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 250mm≤L1≤430mm; and the bonding length L satisfies 250mm≤L≤430mm.

[0072] In this embodiment, the width W1 of the battery cell 200 can be 14.5mm, 16mm, 18mm, 20mm, 21mm, 23mm, etc., and the length L1 of the battery cell 200 can be 250mm, 280mm, 310mm, 340mm, 370mm, 400mm, 430mm, 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 localized stress concentration. By setting appropriate bonding height H and bonding length L, the connection stability between cell 200 and housing 100 can be determined, and the usable space inside housing 100 can be optimized.

[0073] 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 1.3 ≤ K ≤ 1.6; 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, S1 = 2 × H × L × K, satisfies 1040 mm². 2 ≤S1≤3200mm 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 4550 mm². 2 ≤S2≤9600mm 2 .

[0074] 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 1.3, 1.4, 1.5, 1.6, etc.; along both sides of the cell X direction, the bonding surface area S1 between the insulating film 220 and the structural adhesive 300 can specifically be 1040 mm². 2 1500mm 2 2000mm 2 2500mm 2 3000mm 2 3200mm 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 can specifically be 4550 mm². 2 5000mm 2 5500mm 2 6000mm 2 6500mm 2 7000mm 2 7500mm 2 8000mm 2 8500mm 2 9000mm 2 9600mm 2 The specific settings can be customized according to actual usage needs.

[0075] Furthermore, since the surface shape of the insulating film 220 facing the structural adhesive 300 is wavy, 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 around the battery cell 200, the length and width of the insulating film 220 at 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.

[0076] If S1 is too small, such as less than 1040mm 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 3200mm, it 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 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 4550mm... 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 9600mm... 2 This will also increase the amount of structural adhesive 300 used, thereby increasing the space occupied by structural adhesive 300 within the housing 100, resulting in low utilization of the internal space of the housing 100. By reasonably setting the values ​​of S1 and S2, it is ensured that the bonding area between the insulating film 220 and the structural adhesive 300 is subjected to the force in the Y direction to meet the usage requirements; during the use of the battery pack, it prevents the battery cell 200 from falling off from the housing 100 due to bonding failure between the structural adhesive 300 and the insulating film 220.

[0077] 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.

[0078] Table 1

[0079]

[0080]

[0081] As can be seen from Table 1, when H and (S1+S2)σL are small, a tear was found at the insulation film 220 after the vibration test; when (S1+S2)σL 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.

[0082] See also Figures 6 to 11 In one embodiment, the battery cell 200 is a square battery cell. Along the Y-direction of the battery cell, the shear strength of the bond between the insulating film 220 and the structural adhesive 300 satisfies 3.5 MPa ≤ σ ≤ 4.8 MPa; the bonded portion between the insulating film 220 and the structural adhesive 300 subjected to a force in the Y-direction satisfies 2.6 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤10.4×10 6 N·mm.

[0083] 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 3.5 MPa, 3.7 MPa, 3.9 MPa, 4.1 MPa, 4.3 MPa, 4.5 MPa, 4.7 MPa, 4.8 MPa, etc., and can be set according to the usage requirements. By appropriately setting the values ​​of S1, S2, L, and σ, the force in the Y direction at the bonding area between the insulating film 220 and the structural adhesive 300 is made to satisfy 2.6 × 10⁻⁶. 6 N·mm≤(S1+S2)σL≤10.4×10 6 N·mm, to ensure that the insulating film 220 does not detach from the structural adhesive in the Y 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 Y direction at the bonding area between the insulating film 220 and the structural adhesive 300 is too small, such as less than 2.6 × 10 N·mm, it will cause the battery pack to detach. 6 If the force is too high (N·mm), the cell 200 may be subjected to resonant shear force in the Y direction during vehicle operation. Prolonged vibration could lead to adhesion failure between the insulating film 220 and the structural adhesive 300, causing the cell 200 to detach from the battery pack housing 100. If the force on the bonded area between the insulating film 220 and the structural adhesive 300 is too high in the Y direction, such as greater than 10.4 × 10⁻⁶ N·mm, the cell 200 may detach. 6If the force exceeds N·mm, the adhesive layer of structural adhesive 300 may exceed its own bearing limit, causing internal tearing of the adhesive layer. This reduces the effective bonding surface area between insulating film 220 and structural adhesive 300, thereby reducing the force in the Y direction at the bonding area between insulating film 220 and structural adhesive 300. Consequently, the battery cell 200 cannot be stably installed in the housing 100, ultimately causing the battery cell 200 to detach.

[0084] In one embodiment, the thickness T1 of the structural adhesive 300 satisfies 0.5mm≤T1≤2.0mm; and the bonding height H of the structural adhesive 300 along the Z direction on both sides of the cell in the X direction satisfies 1.5mm≤H≤3.5mm.

[0085] 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 Y 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.

[0086] 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, 2mm, 2.5mm, 3mm, 3.5mm, 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 is the height to which the structural adhesive 300 covers the two sides of the battery cell 200, 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 3.5mm, 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 Y 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.

[0087] 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; and the bonding length L satisfies 120mm≤L≤260mm.

[0088] 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, 170mm, 200mm, 230mm, 260mm, 290mm, 320mm, 350mm, 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, 140mm, 160mm, 180mm, 200mm, 220mm, 240mm, 260mm, etc., and L is less than L2. This ensures that there is 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 also avoiding excessive use of structural adhesive 300 to avoid occupying too much usable space inside 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 1.3 ≤ K ≤ 1.6; 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 780 mm². 2 ≤S1≤1960mm 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 4550 mm². 2 ≤S2≤11200mm 2 .

[0090] 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 1.3, 1.4, 1.5, 1.6, etc.; along both sides of the cell X direction, the bonding surface area S1 between the insulating film 220 and the structural adhesive 300 can specifically be 780 mm². 2 900mm 2 1000mm 2 1100mm 2 1200mm 2 1300mm 2 1400mm 2 1500mm2 1600mm 2 1700mm 2 1800mm 2 1920mm 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 can specifically be 4550 mm². 2 6000mm 2 7500mm 2 9000mm 2 10500mm 2 11200mm 2 The specific settings can be customized according to actual usage needs.

[0091] If S1 is too small, such as less than 780mm 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 1960 mm, it 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 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 4550mm... 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 local stress concentration of 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 11200mm... 2 This will also increase the amount of structural adhesive 300 used, thereby increasing the space occupied by structural adhesive 300 within the housing 100, resulting in low utilization of the internal space of the housing 100. By reasonably setting the values ​​of S1 and S2, it is ensured that the bonding area between the insulating film 220 and the structural adhesive 300 is subjected to the force in the Y direction to meet the usage requirements; during the use of the battery pack, it prevents the battery cell 200 from falling off from the housing 100 due to bonding failure between the structural adhesive 300 and the insulating film 220.

[0092] 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.

[0093] Table 2

[0094]

[0095]

[0096] As can be seen from Table 2, when H and (S1+S2)σL are small, a tear was found at the insulation film 220 after the vibration test; when (S1+S2)σL 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.

[0097] In one embodiment, the wave amplitude of the insulating film is I, which satisfies 15μm≤I≤40μm, and the spacing between adjacent wave peaks is J, which satisfies 120μm≤J≤200μm; the thickness T2 of the insulating film 220 satisfies 0.1mm≤T2≤0.15mm.

[0098] In this embodiment, the thickness T2 of the insulating film 220 can specifically be 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, etc. By reasonably setting the thickness of the insulating film 220, the insulation performance of the insulating film 220 can be guaranteed. The outer surface of the insulating film 220 is made wavy, so that the outer surface of the insulating film 220 has a periodic undulating shape, that is, there are continuous peaks and troughs, thus forming a regular curved alternating structure. When the structural adhesive 300 is coated on the insulating film 220, the structural adhesive 300 can fully fill the troughs, thereby increasing the bonding force between the structural adhesive 300 and the insulating film 220 and reducing the risk of detachment between the insulating film 220 and the structural adhesive 300. Furthermore, the wave amplitude I, i.e., the vertical distance from the trough to the crest, can be 15μm, 18μm, 22μm, 25μm, 28μm, 32μm, 35μm, 38μm, 40μm, etc.; the spacing J between adjacent crests, i.e., the horizontal distance between two adjacent crests, can be 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 200μm, etc., which can be set according to actual needs. By setting appropriate wave amplitude I and spacing J between adjacent crests, the contact area between the insulating film 220 and the structural adhesive 300 can be further increased, thereby improving friction and adhesion strength, ensuring a firm bond between the insulating film 220 and the structural adhesive 300, and preventing the battery cell from detaching from the casing.

[0099] 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 by, include: Box; Multiple battery cells are arranged along the X direction of the housing and housed within the housing. Each battery cell has a battery cell housing, and the outer surface of the battery cell housing is covered with an insulating film. The outer surface of the insulating film is wavy. 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 site between the insulating film and the structural adhesive satisfies 2.6 x 10 6 N·mm≤(S1+S2)σL≤16 x 10 6 N·mm; 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; 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 adhesion between the insulating film and the structural adhesive along the Y direction of the battery cell.

2. The battery pack of claim 1, wherein, The electric core is a blade electric core, and the shear strength between the insulating film and the structural adhesive along the Y direction of the electric core satisfies 3.5 Mpa≤σ≤4.8 Mpa; the adhesive part between the insulating film and the structural adhesive is subjected to the force in the Y direction, and satisfies 5.2×10 6 N·mm≤(S1+S2)σL≤16×10 6 N·mm.

3. The battery pack of claim 2, wherein, 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≤4mm.

4. The battery pack of claim 3, wherein, The width W1 of the battery cell satisfies 14.5mm≤W1≤23mm; the length L1 of the battery cell satisfies 250mm≤L1≤430mm; and the bonding length L satisfies 250mm≤L≤430mm.

5. The battery pack of claim 4, wherein, The ratio K of the surface area of the side surface of the insulating film facing the structural adhesive to the profile area of the insulating film satisfies 1.3≤K≤1.6; the bonding surface area S1 between the insulating film and the structural adhesive along the X direction of the battery cell satisfies S1=2×H×L×K, and 1040mm 2 ≤S1≤3200mm 2 ; the bonding surface area S2 between the insulating film and the structural adhesive on the bottom surface of the battery cell satisfies S2=W1×L×K, and 4550mm 2 ≤S2≤9600mm 2 .

6. The battery pack of claim 1, wherein, The electric core is a square electric core, and the shear strength between the insulating film and the structural adhesive along the Y direction of the electric core satisfies 3.5 Mpa<=sigma<=4.8 Mpa; the bonding part between the insulating film and the structural adhesive is subjected to a force in the Y direction, and satisfies 2.6*10 6 N*mm<=(S1+S2)*sigma*L<=10.4*10 6 N*mm.

7. The battery pack of claim 6, wherein, 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≤3.5mm.

8. The battery pack of claim 7, wherein, The width W2 of the battery cell satisfies 25mm≤W2≤65mm; the length L2 of the battery cell satisfies 150mm≤L2≤380mm; and the bonding length L satisfies 120mm≤L≤260mm.

9. The battery pack of claim 8, wherein, The ratio K of the surface area of ​​the insulating film facing the structural adhesive to the outline area of ​​the insulating film satisfies 1.3 ≤ K ≤ 1.6; 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 780 mm². 2 ≤S1≤1920mm 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 4550 mm². 2 ≤S2≤11200mm 2 .

10. The battery pack of any one of claims 1-9, wherein, The wave amplitude of the insulating film is I, which satisfies 15μm≤I≤40μm, and the spacing between adjacent wave peaks is J, which satisfies 120μm≤J≤200μm; the thickness of the insulating film is T2, which satisfies 0.1mm≤T2≤0.15mm.

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