Battery pack

Abstract

The utility model relates to battery technical field discloses battery package, include: box, multiple electric core and structural glue, multiple electric core arranges and is accomodated in the box, each electric core has electric core casing, the outer surface of electric core casing is covered with insulating film, structural glue is coated in each electric core casing along the relative two side surfaces and the bottom surface of thickness direction, structural glue and insulating film are bonded and fixed, along the two sides of electric core casing thickness direction, the bonding area between insulating film and structural glue is S1, in the bottom surface of electric core casing, the bonding area between insulating film and structural glue is S2, along the height direction of electric core casing, the shear strength between insulating film and structural glue is bonded and is sigma, and the pullout strength is gamma, the bonding part between insulating film and structural glue is the pulling force of electric core casing's height direction, satisfies S1x sigma + S2x gamma is greater than or equal to 1.8F. The utility model can significantly improve the bonding strength of structural glue and insulating film by the reasonable collocation bonding area between structural glue and insulating film.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to battery packs. 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 blue film, and a cover plate top cover. The cover is welded to the casing and forms a sealed space protecting the electrode assembly. The bare cell insulating sheets cover the electrode assembly to protect it and prevent short circuits caused by contact between the electrode assembly and the casing. The electrode assembly end plates secure the tabs and provide space for their protection. The insulating blue film mainly covers the outside of the casing, providing external insulation.

[0004] However, since the insulating blue film is mainly made of polymer materials such as PET (polyethylene terephthalate) and PP (polypropylene), and these polymer materials have relatively low surface energy, that is, low adhesive strength, when structural adhesive is used to bond the insulating blue film on the outside of the casing to the battery cell, the bonding effect is poor, and bonding failure is likely to occur, causing the battery cell to detach from the casing. Utility Model Content

[0005] In view of this, the present invention provides a battery pack to solve the problem of low adhesion of the insulating film and easy adhesion failure at the joint between the insulating film and the structural adhesive, which leads to the separation of the battery cell from the casing.

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

[0007] Box;

[0008] Multiple battery cells are arranged and housed in the housing, each battery cell having a battery cell housing, the outer surface of which is covered with an insulating film;

[0009] Structural adhesive is applied to two opposite sides and the bottom surface of each of the battery cell housings along the thickness direction. The structural adhesive is bonded and fixed to the insulating film to fix each of the battery cells to the housing.

[0010] Along both sides of the thickness direction of the battery cell casing, the bonding area between the insulating film and the structural adhesive is S1; on the bottom surface of the battery cell casing, the bonding area between the insulating film and the structural adhesive is S2; along the height direction of the battery cell casing, the shear strength of the bond between the insulating film and the structural adhesive is σ, and the pull-out strength is γ; the tensile force F exerted on the bonded portion between the insulating film and the structural adhesive in the height direction of the battery cell casing satisfies S1×σ+S2×γ≥1.8F.

[0011] Beneficial Effects: This invention coats the outer surface of the battery cell casing with an insulating film, ensuring the insulation performance of the casing. Structural adhesive is simultaneously applied to the bottom surface and two opposite sides along the thickness direction of the battery cell casing, ensuring sufficient bonding area between the adhesive and the insulating film, guaranteeing bonding strength. By controlling the bonding area between the adhesive and the insulating film, the shear strength, pull-out strength, and tensile force along the height direction of the battery cell casing, as well as the tensile force on the bonded portion between the insulating film and the adhesive, satisfy the aforementioned relationships. This significantly improves the bonding strength between the adhesive and the insulating film in the height direction, thereby enhancing the stability of the battery cell after installation in the casing and reducing the risk of the battery cell detaching from the casing due to the peeling of the insulating film and the adhesive, thus improving the safety performance of the battery pack. Furthermore, the adhesive bonding area calculated using the above formula is within a reasonable range, ensuring bonding strength while reducing the amount of adhesive used, thereby lowering operating costs.

[0012] In one optional embodiment, the battery cell is a square cell, meeting the requirement of 1000mm². 2 ≤S1≤2500mm 2 6000mm 2 ≤S2≤11000mm 2 , 2.5Mpa≤σ≤3.5Mpa, 2Mpa≤γ≤3.5Mpa.

[0013] Beneficial effects: In applications using square battery cells, the cell casing is relatively short in length and large in width. By controlling S1 within a suitable range, the shear strength of the insulating film and structural adhesive can be ensured, while reducing the amount of structural adhesive used and lowering operating costs. By controlling S2 within a suitable range, the pull-out strength of the insulating film and structural adhesive can be ensured, while also reducing the amount of structural adhesive used and lowering operating costs. By controlling σ within a suitable range, horizontal displacement of the battery cell can be prevented. By controlling γ within a suitable range, vertical pull-out of the battery cell can be prevented.

[0014] In one optional embodiment, S1 = 2 × (H1 + T1) × L1, where H1 is the coating height of the structural adhesive along the height direction of the battery cell housing on both sides of the thickness direction, T1 is the thickness of the insulating film along the height direction of the battery cell housing, and L1 is the coating length of the structural adhesive, satisfying 3mm ≤ H1 ≤ 6mm, 0.1mm ≤ T1 ≤ 0.15mm, and 130mm ≤ L1 ≤ 270mm.

[0015] Beneficial effects: The bonding area S1 between the structural adhesive and the insulating film is determined by the coating height H1 of the structural adhesive, the thickness T1 of the insulating film along the height direction of the cell casing, and the coating length L1 of the structural adhesive. Controlling H1, T1, and L1 within a suitable range means controlling S1 within a suitable range. If S1 is too small, the shear strength of the insulating film and the structural adhesive is low, and the side of the cell is prone to detaching from the casing. If S1 is too large, too much structural adhesive is applied, wasting material, increasing the cost of use, and making the battery pack heavier.

[0016] In one optional implementation, S2 = (W1 + 2T4) × L1, where W1 is the width of the battery cell housing and T4 is the thickness of the insulating film along the thickness direction of the battery cell housing, satisfying 25mm ≤ W1 ≤ 75mm and 0.1mm ≤ T4 ≤ 0.15mm.

[0017] Beneficial effects: The bonding area S2 between the structural adhesive and the insulating film is determined by the width W1 of the cell casing, the thickness T4 of the insulating film along the thickness direction of the cell casing, and the coating length L1 of the structural adhesive. Further controlling W1 and T4 within appropriate ranges allows for the control of S2 within a suitable range. If S2 is too small, the pull-out strength between the insulating film and the structural adhesive is low, and the bottom surface of the cell is prone to detaching from the casing. If S2 is too large, excessive structural adhesive is applied, wasting material, increasing usage costs, and making the battery pack heavier.

[0018] In one optional embodiment, the battery cell is a blade battery cell, satisfying S1×σ+S2×γ≥2F, 1500mm² 2 ≤S1≤3500mm 2 3500mm 2 ≤S2≤5000mm 2 , 2.5Mpa≤σ≤3.5Mpa, 2Mpa≤γ≤3.5Mpa.

[0019] Beneficial effects: In the application scenario of blade cells, the cell shell is longer but narrower. Therefore, the upper and lower limits of S1 are increased and the upper and lower limits of S2 are decreased. The upper limit of the above formula is also adjusted to ensure that there is sufficient bonding area between the insulating film and the structural adhesive, that is, to ensure sufficient bonding strength, while avoiding waste of structural adhesive and reducing the cost of use.

[0020] In one optional embodiment, S1 = 2 × (H1 + T1) × L1, where H1 is the coating height of the structural adhesive along the height direction of the battery cell housing on both sides of the thickness direction, T1 is the thickness of the insulating film along the height direction of the battery cell housing, and L1 is the coating length of the structural adhesive, satisfying 3mm ≤ H1 ≤ 8mm, 0.1mm ≤ T1 ≤ 0.15mm, and 180mm ≤ L1 ≤ 350mm.

[0021] Beneficial effects: In the application of blade cells, increasing the coating height H1 and coating length L1 of the structural adhesive can increase S1, ensuring sufficient shear strength between the insulating film and the structural adhesive, saving the amount of structural adhesive used, and reducing the cost of use.

[0022] In one optional implementation, S2 = (W1 + 2T4) × L1, where W1 is the width of the battery cell housing and T4 is the thickness of the insulating film along the thickness direction of the battery cell housing, satisfying 14mm ≤ W1 ≤ 25mm and 0.1mm ≤ T4 ≤ 0.15mm.

[0023] Beneficial effects: In the application scenario of blade cells, the width of the cell housing is relatively narrow, thus reducing the width range of the cell housing, while maintaining S2 within a suitable range, ensuring sufficient pull-out strength between the insulating film and the structural adhesive, saving the amount of structural adhesive used, and reducing the cost of use.

[0024] In one optional embodiment, the surface energy of the insulating film is Y, which satisfies 35mN / m≤Y≤55mN / m.

[0025] Beneficial effects: By selecting specific materials for the insulating film or by performing surface treatment on the insulating film and selecting appropriate surface energy, the structural adhesive can fully wet the outer surface of the insulating film and form an effective bond, thereby improving the bonding effect between the insulating film and the structural adhesive.

[0026] In one optional embodiment, the adhesive strength of the structural adhesive is R, which satisfies R≥8MPa, and the elongation at break of the structural adhesive is δ, which satisfies δ≥100%.

[0027] Beneficial effects: By controlling the adhesive strength and elongation at break of the structural adhesive, it is possible to ensure that the structural adhesive has sufficient buffering capacity to cushion the impact of external forces on the battery pack, thereby further improving the safety of the battery pack.

[0028] In one optional embodiment, the thickness of the structural adhesive located between adjacent cell housings is T2, satisfying 0.5mm≤T2≤2mm;

[0029] And / or, the thickness of the structural adhesive located between the outermost cell housing and the box body is T3, satisfying 0.5mm≤T3≤2mm.

[0030] Beneficial effects: By controlling the thickness of the structural adhesive between adjacent cell housings and / or between the outermost cell housing and the casing within a suitable range, it is possible to ensure that there is a sufficient thickness of structural adhesive between adjacent cell housings and / or between the outermost cell housing and the casing to buffer external forces, improve bonding strength, prevent cell detachment, and also to use the amount of structural adhesive reasonably, thereby reducing usage costs. 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 schematic diagram of the structure of a battery pack according to an embodiment of the present utility model;

[0033] Figure 2 for Figure 1 A sectional view;

[0034] Figure 3 for Figure 2 A magnified view of a section at point A in the middle;

[0035] Figure 4 This is a partial structural schematic diagram of a battery pack according to an embodiment of the present utility model;

[0036] Figure 5 This is a schematic diagram of the structure of a battery cell in a battery pack according to an embodiment of the present invention;

[0037] Figure 6 An exploded view of a battery cell in a battery pack according to an embodiment of this utility model;

[0038] Figure 7 This is a schematic diagram of the structure of a battery pack according to another embodiment of the present invention;

[0039] Figure 8 for Figure 7 The main view;

[0040] Figure 9 for Figure 8 A magnified view of a section at point B in the middle;

[0041] Figure 10This is a partial structural schematic diagram of a battery pack according to another embodiment of the present invention;

[0042] Figure 11 This is a schematic diagram of the structure of a battery cell in a battery pack according to another embodiment of the present invention;

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

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

[0045] 1. Housing; 2. Battery cell; 201. Battery cell housing; 202. Insulating film; 203. Cover plate; 204. Electrode assembly; 205. Insulating sheet; 3. 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] In this embodiment of the invention, the "battery pack" is formed by electrically connecting a certain number of battery cells together and placing them in a housing to protect the battery cells from external impacts, heat, vibration, etc. The battery pack contains two or more battery cells, the specific number depending on the application of the battery pack and the parameters of individual battery groups.

[0048] In this embodiment of the invention, a "cell" refers to a single battery cell capable of independent charging and discharging. The components of a cell may include a positive electrode, a negative electrode, a separator, an electrolyte, and a housing assembly for encapsulating the positive electrode, negative electrode, separator, and electrolyte. This embodiment of the invention does not impose any particular limitation on the type or shape of the cell; it can be a blade cell, a square cell, or any other type of cell. The cell in this embodiment of the invention can be a lithium-ion cell, a potassium-ion cell, a sodium-ion cell, a lithium-sulfur cell, etc., with lithium-ion cells being particularly preferred. During the charging and discharging process, active ions repeatedly insert and extract between the positive and negative electrode plates. The electrolyte acts as a conductor of ions between the positive and negative electrode plates.

[0049] The following is combined with Figures 1 to 12 The following describes embodiments of the present invention.

[0050] According to embodiments of the present invention, such as Figure 1 and Figure 2As shown, a battery pack is provided, mainly comprising: a housing 1, multiple battery cells 2, and structural adhesive 3. The multiple battery cells 2 are arranged and housed within the housing 1. Each battery cell 2 has a cell housing 201, the outer surface of which is covered with an insulating film 202. The structural adhesive 3 is applied to two opposite sides and the bottom surface of each cell housing 201 along its thickness direction. The structural adhesive 3 is bonded and fixed to the insulating film 202, thereby securing each battery cell 2 to the housing 1.

[0051] Along both sides of the thickness direction of the cell housing 201, the bonding area between the insulating film 202 and the structural adhesive 3 is S1, in mm. 2 On the bottom surface of the cell housing 201, the bonding area between the insulating film 202 and the structural adhesive 3 is S2, in mm. 2 Along the height direction of the cell housing 201, the shear strength of the bond between the insulating film 202 and the structural adhesive 3 is σ, in MPa, and the pull-out strength is γ, in MPa; the tensile force F, in N, on the bonded portion between the insulating film 202 and the structural adhesive 3 in the height direction of the cell housing 201 satisfies S1×σ+S2×γ≥1.8F.

[0052] Therefore, the battery pack provided in this embodiment of the present invention, by covering the outer surface of the cell housing 201 with an insulating film 202, can ensure the insulation performance of the cell housing 201. Structural adhesive 3 is simultaneously applied to the bottom surface of the cell housing 201 and two opposite sides in the thickness direction, ensuring sufficient bonding area between the structural adhesive 3 and the insulating film 202, and guaranteeing bonding strength. By controlling the bonding area between the structural adhesive 3 and the insulating film 202, the shear strength, pull-out strength along the height direction of the cell housing 201, and the tensile force along the height direction of the bonded portion between the insulating film 202 and the structural adhesive 3 satisfy the above-mentioned relationships, which can significantly improve the bonding strength between the structural adhesive 3 and the insulating film 202 in the height direction. This improves the firmness of the cell 2 after installation in the housing 1, reduces the risk of the cell 2 falling off the housing 1 due to peeling of the insulating film 202 and the structural adhesive 3, and thus improves the safety performance of the battery pack. In addition, the bonding area of ​​structural adhesive 3 calculated by the above formula is within a reasonable range of use. While ensuring the bonding strength, it also helps to reduce the amount of structural adhesive 3 used, thereby reducing the cost of use.

[0053] Specifically, the height direction of the cell casing 201 is also the height direction of the housing 1, such as Figure 1 As indicated by arrow H in the diagram. F represents the total tensile force experienced by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height of the cell housing 201 during vibration testing or use. This force can be obtained through testing, such as... Figure 1As shown, S1 represents the total bonding area between the insulating film 202 and the structural adhesive 3 on two opposite sides of each cell housing 201 along the thickness direction. The larger S1 and S2 are, the higher the bonding strength and the stronger the connection between the cell 2 and the housing 1. Similarly, the larger σ and γ are, the higher the bonding strength.

[0054] In this embodiment of the invention, the insulating film 202 can be made of polymer materials such as polypropylene (PP), polycarbonate (PC), or polyethylene terephthalate (PET). The structural adhesive 3 can be made of acrylic structural adhesive, epoxy structural adhesive, etc.

[0055] In one embodiment, such as Figure 1 As shown, cell 2 is a square cell, meeting the 1000mm² requirement. 2 ≤S1≤2500mm 2 6000mm 2 ≤S2≤11000mm 2 2.5 MPa ≤ σ ≤ 3.5 MPa, 2 MPa ≤ γ ≤ 3.5 MPa. In the application scenario of square battery cells, the length of the battery cell casing 201 is relatively small, while the width is relatively large. By controlling S1 within a suitable range, the shear strength of the insulating film 202 and the structural adhesive 3 can be ensured, and the amount of structural adhesive 3 used can be reduced, thus lowering the cost of use. By controlling S2 within a suitable range, the pull-out strength of the insulating film 202 and the structural adhesive 3 can be ensured, and the amount of structural adhesive 3 used can be reduced, thus lowering the cost of use. By controlling σ within a suitable range, horizontal displacement of the battery cell 2 can be prevented. By controlling γ within a suitable range, vertical pull-out of the battery cell 2 can be prevented.

[0056] Specifically, such as Figure 6 As shown, the top of the cell housing 201 has an opening, and the cell 2 also includes a cover plate 203, which covers the opening of the cell housing 201. The cell housing 201 is provided with an electrode group 204, and the electrode group 204 is covered with an insulating sheet 205.

[0057] Furthermore, in one embodiment, such as Figure 3 and Figure 4As shown, S1 = 2 × (H1 + T1) × L1, where H1 is the coating height of structural adhesive 3 along the height direction of the cell housing 201 on both sides of the thickness direction (referred to as coating height), T1 is the thickness of insulating film 202 along the height direction of the cell housing 201, and L1 is the coating length of structural adhesive 3, satisfying 3mm ≤ H1 ≤ 6mm, 0.1mm ≤ T1 ≤ 0.15mm, and 130mm ≤ L1 ≤ 270mm. The bonding area S1 between structural adhesive 3 and insulating film 202 is determined by the coating height H1 of structural adhesive 3, the thickness T1 of insulating film 202 along the height direction of the cell housing 201, and the coating length L1 of structural adhesive 3. Controlling H1, T1, and L1 within a suitable range means controlling S1 within a suitable range. If S1 is too small, the shear strength of the insulating film 202 and the structural adhesive 3 will be low, and the side of the cell 2 will easily detach from the casing 1. If S1 is too large, too much structural adhesive 3 will be applied, wasting materials, increasing the cost of use, and making the battery pack heavier.

[0058] It should be noted that the coating length L1 of structural adhesive 3 refers to the dimension of structural adhesive 3 along the length direction of the housing 1, that is, along the length direction of the cell casing 201. The length direction of the housing 1 is as follows: Figure 1 As indicated by arrow L in the diagram, the coating length L1 of the structural adhesive 3 can be selected to completely cover the length of the insulating film 202, or it can be selected to partially cover the length of the insulating film 202, depending on the needs.

[0059] For example, such as Figure 4 and Figure 5 As shown, structural adhesive 3 partially covers the insulating film 202 along the length of the housing 1, which is also the length of the insulating film 202. The length of the insulating film 202, which is also the length of the battery cell 2, is L2, satisfying 150mm≤L2≤380mm.

[0060] It should be noted that the structural adhesive 3 is generally uniformly coated on the two opposite sides and the bottom surface of each cell housing 201 along the thickness direction. When calculating S1, the coating height H1 of the structural adhesive 3 can be the average coating height of the structural adhesive 3. Similarly, the coating length L1 of the structural adhesive 3 can be the average length.

[0061] Furthermore, in one embodiment, such as Figure 5 and Figure 6As shown, S2 = (W1 + 2T4) × L1, where W1 is the width of the cell housing 201, and T4 is the thickness of the insulating film 202 along the thickness direction of the cell housing 201, satisfying 25mm ≤ W1 ≤ 75mm and 0.1mm ≤ T4 ≤ 0.15mm. Specifically, the width of the cell 2, i.e., the width of the insulating film 202, is W2, W2 = (W1 + 2T4). The bonding area S2 between the structural adhesive 3 and the insulating film 202 is determined by the width W1 of the cell housing 201, the thickness T1 of the insulating film 202 along the thickness direction of the cell housing 201, and the coating length L1 of the structural adhesive 3. By further controlling W1 and T4 within a suitable range, S2 can be controlled within a suitable range. If S2 is too small, the pull-out strength of the insulating film 202 and the structural adhesive 3 will be low, and the bottom surface of the cell 2 will easily detach from the casing 1. If S2 is too large, too much structural adhesive 3 will be applied, wasting materials, increasing the cost of use, and making the battery pack heavier.

[0062] Specifically, such as Figure 2 As shown, the cross-section of the structural adhesive 3 on a single battery cell 2 is typically U-shaped, and the structural adhesive 3 between adjacent battery cells 2 is bonded together to form a whole. The thickness T4 of the insulating film 202 along the thickness direction of the battery cell housing 201 is typically equal to the thickness of the insulating film 202 along the height direction of the battery cell housing 201.

[0063] In one embodiment, such as Figures 7 to 12 As shown, cell 2 is a blade cell, satisfying S1×σ+S2×γ≥2F, 1500mm² 2 ≤S1≤3500mm 2 3500mm 2 ≤S2≤5000mm 2 , 2.5Mpa≤σ≤3.5Mpa, 2Mpa≤γ≤3.5Mpa.

[0064] In the application scenario of blade battery cells, the length of the battery cell housing 201 is relatively large, but the width is relatively small. Therefore, the upper and lower limits of S1 are increased and the upper and lower limits of S2 are decreased. The upper limit of the above formula is also adjusted to ensure that there is sufficient bonding area between the insulating film 202 and the structural adhesive 3, that is, to ensure sufficient bonding strength, while avoiding waste of structural adhesive 3 and reducing the cost of use.

[0065] Further, in one embodiment, S1 = 2 × (H1 + T1) × L1, where H1 is the coating height of the structural adhesive 3 along the height direction of the cell housing 201 on both sides of the thickness direction, T1 is the thickness of the insulating film 202 along the height direction of the cell housing 201, and L1 is the length of the structural adhesive 3, satisfying 3mm ≤ H1 ≤ 8mm, 0.1mm ≤ T1 ≤ 0.15mm, and 130mm ≤ L1 ≤ 270mm. In the application scenario of blade cells, increasing the coating height H1 and coating length L1 of the structural adhesive 3 can increase S1, ensuring sufficient shear strength between the insulating film 202 and the structural adhesive 3, saving the amount of structural adhesive 3 used, and reducing the cost of use.

[0066] Furthermore, the length of the insulating film 202, which is also the length of the battery cell 2, is L2, which satisfies 380mm≤L2≤580mm.

[0067] Furthermore, in one embodiment, S2 = (W1 + 2T4) × L1, where W1 is the width of the cell housing 201, and T4 is the thickness of the insulating film 202 along the thickness direction of the cell housing 201, satisfying 14mm ≤ W1 ≤ 25mm and 0.1mm ≤ T4 ≤ 0.15mm. In the application scenario of blade cells, the width of the cell housing 201 is relatively narrow, thus reducing the width range of the cell housing 201 while maintaining S2 within a suitable range. This ensures sufficient pull-out strength between the insulating film 202 and the structural adhesive 3, saves on the amount of structural adhesive 3 used, and reduces usage costs.

[0068] In one embodiment, the surface energy of the insulating film 202 is Y, satisfying 35mN / m≤Y≤55mN / m. By selecting the specific material of the insulating film 202, or by performing surface treatment on the insulating film 202, and selecting a suitable surface energy, the structural adhesive 3 can fully wet the outer surface of the insulating film 202 and form an effective bond, thereby improving the bonding effect between the insulating film 202 and the structural adhesive 3.

[0069] In one embodiment, the adhesive strength of the structural adhesive 3 is R, which satisfies R≥8MPa, and the elongation at break of the structural adhesive 3 is δ, which satisfies δ≥100%. By controlling the adhesive strength and elongation at break of the structural adhesive 3, it is possible to ensure that the structural adhesive 3 has sufficient buffering capacity to cushion the impact of external forces on the battery pack, thereby further improving the safety of the battery pack.

[0070] In one embodiment, the thickness of the structural adhesive 3 located between adjacent cell housings 201 is T2, which satisfies 0.5mm≤T2≤2mm;

[0071] And / or, the thickness of the structural adhesive 3 located between the outermost cell housing 201 and the box 1 is T3, which satisfies 0.5mm≤T3≤2mm.

[0072] By controlling the thickness of the structural adhesive 3 between adjacent cell housings 201 and / or between the outermost cell housing 201 and the housing 1 within a suitable range, it is possible to ensure that there is a sufficient thickness of structural adhesive 3 between adjacent cell housings 201 and / or between the outermost cell housing 201 and the housing 1, so as to buffer external forces, improve bonding strength, prevent cell 2 from falling off, and also make reasonable use of the amount of structural adhesive 3 to reduce usage costs.

[0073] In this embodiment of the invention, the shear strength σ and pull-out strength γ of the bond between the insulating film 202 and the structural adhesive 3 along the height direction of the battery cell housing 201 can be measured using a universal tensile testing machine.

[0074] For example, the shear test specimens are prepared according to GB / T 7124. Two shear test specimens with dimensions of 100mm × 25mm × 2mm are cut. Structural adhesive 3 is applied to one side of the insulating film 202 of the two shear test specimens, and the bonding area between the insulating film 202 and the structural adhesive 3 is 25mm × 25mm. The two shear test specimens are then fixed together. The shear test specimens are made of Al3003, and the insulating film 202 is made of PET film. 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. After that, the test is started. The two bonded shear test specimens are fixed on the fixtures respectively. A universal tensile testing machine is used to stretch the upper end of one shear test specimen and the lower end of the other shear test specimen at a stretching speed of 50mm / min. The values ​​are read, and the shear strength σ is obtained by dividing the force on the shear test specimen by the bonding area of ​​25mm × 25mm.

[0075] In addition, the pull-out test specimens were prepared according to GB / T 6329. Two 100mm×25mm×2mm pull-out test specimens were cut. Structural adhesive 3 was applied to one side of the insulating film 202 of the two test specimens, with a bonding area of ​​25mm×25mm between the insulating film 202 and the structural adhesive 3. The two pull-out test 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 202. The pull-out test specimens were repeatedly rolled five or more times using a 2kg roller and then left to stand at room temperature (23±2℃) for 24 hours. After that, the test was started. The two bonded pull-out test specimens were fixed on the fixtures respectively. A universal tensile testing machine was used to stretch the upper surface of one pull-out test specimen and the lower surface of the other pull-out test specimen at a stretching speed of 50mm / min. The values ​​were recorded, and the pull-out strength γ was obtained by dividing the force on the pull-out test specimen by the bonding area of ​​25mm×25mm.

[0076] The process parameters of the battery pack of this utility model are described in further detail below with reference to specific embodiments. These examples should not be construed as limiting the scope of protection claimed by this utility model.

[0077] Example 1:

[0078] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 4.4 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 270 mm. The width W1 of cell housing 201 is 25 mm. Therefore, S1 = 2430 mm. 2 S2 = 6804 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.5 MPa, and the pull-out strength γ is 2.53 MPa. Therefore, S1×σ+S2×γ=23289.1N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 12438.4N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0079] Example 2:

[0080] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 4.3 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 250 mm. The width W1 of cell housing 201 is 28 mm. Therefore, S1 = 2200 mm. 2 S2 = 7050mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.8 MPa, and the pull-out strength γ is 2.75 MPa. Therefore, S1×σ+S2×γ=25547.5N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 13693.1N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0081] Example 3:

[0082] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 4.5 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 210 mm. The width W1 of cell housing 201 is 30 mm. Therefore, S1 = 1932 mm. 2 S2 = 6342mm 2Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 3.35 MPa. Therefore, S1×σ+S2×γ=27428.1N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 14737.8N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0083] Example 4:

[0084] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 5mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.12mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.12mm. The coating length L1 of structural adhesive 3 is 180mm. The width W1 of cell housing 201 is 35mm. Therefore, S1 = 1843mm. 2 S2 = 6343mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.5 MPa, and the pull-out strength γ is 3.5 MPa. Therefore, S1×σ+S2×γ=28652.4N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 15418N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0085] Example 5:

[0086] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 3mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.12mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.12mm. The coating length L1 of structural adhesive 3 is 200mm. The width W1 of cell housing 201 is 40mm. Therefore, S1 = 1248mm. 2 S2 = 8048mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 3.09 MPa. Therefore, S1×σ+S2×γ=28861.9N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 15534.4N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0087] Example 6:

[0088] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 3.5 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 150 mm. The width W1 of cell housing 201 is 50 mm. Therefore, S1 = 1080 mm. 2 S2 = 7530mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3 MPa, and the pull-out strength γ is 3.23 MPa. Therefore, S1×σ+S2×γ=27561.9N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 14812.2N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0089] Example 7:

[0090] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 3.9 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.11 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.11 mm. The coating length L1 of structural adhesive 3 is 180 mm. The width W1 of cell housing 201 is 60 mm. Therefore, S1 = 1444 mm. 2 S2 = 10840mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 2 MPa. Therefore, S1×σ+S2×γ=26298.7N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 14110.4N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0091] Example 8:

[0092] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 3.8 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.15 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.15 mm. The coating length L1 of structural adhesive 3 is 130 mm. The width W1 of cell housing 201 is 65 mm. Therefore, S1 = 1027 mm. 2 S2 = 8489 mm 2Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 2.2 MPa. Therefore, S1×σ+S2×γ=21962.2N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 11701.2N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0093] Example 9:

[0094] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 4.5 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.15 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.15 mm. The coating length L1 of structural adhesive 3 is 150 mm. The width W1 of cell housing 201 is 72 mm. Therefore, S1 = 1395 mm. 2 S2 = 10845mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.6 MPa, and the pull-out strength γ is 2.3 MPa. Therefore, S1×σ+S2×γ=28570.5N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 15372.5N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0095] Example 10:

[0096] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 6mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.15mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.15mm. The coating length L1 of structural adhesive 3 is 135mm. The width W1 of cell housing 201 is 75mm. Therefore, S1 = 1661mm. 2 S2 = 10166 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.8 MPa, and the pull-out strength γ is 2.65 MPa. Therefore, S1×σ+S2×γ=31588N, and the tensile force F exerted on the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 17040.9N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0097] Comparative Example 1:

[0098] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 4.3 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 250 mm. The width W1 of cell housing 201 is 28 mm. Therefore, S1 = 2200 mm. 2 S2 = 7050mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.8 MPa, and the pull-out strength γ is 2.75 MPa. Therefore, S1×σ+S2×γ=25547.5N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 14693.1N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0099] Comparative Example 2:

[0100] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 5mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.12mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.12mm. The coating length L1 of structural adhesive 3 is 180mm. The width W1 of cell housing 201 is 35mm. Therefore, S1 = 1843mm. 2 S2 = 6343mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.5 MPa, and the pull-out strength γ is 3.5 MPa. Therefore, S1×σ+S2×γ=28652.4N, and the tensile force F of the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 16418N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0101] Comparative Example 3:

[0102] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 3.5 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 150 mm. The width W1 of cell housing 201 is 50 mm. Therefore, S1 = 1080 mm. 2 S2 = 7530mm 2Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3 MPa, and the pull-out strength γ is 3.23 MPa. Therefore, S1×σ+S2×γ=27561.9N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 15812.2N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0103] Comparative Example 4:

[0104] Cell 2 is a square cell. The coating height H1 of structural adhesive 3 is 3.8 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.15 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.15 mm. The coating length L1 of structural adhesive 3 is 130 mm. The width W1 of cell housing 201 is 65 mm. Therefore, S1 = 1027 mm. 2 S2 = 8489 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 2.2 MPa. Therefore, S1×σ+S2×γ=21962.2N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 12701.2N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 1.

[0105] Table 1: Test Results of Square Battery Cells

[0106]

[0107] As can be seen from Table 1, in Examples 1 to 10, the condition S1×σ+S2×γ≥1.8F is met. During the test, the insulating film 202 and the structural adhesive 3 are well bonded, and the battery cell 2 does not fall off the housing 1.

[0108] In Comparative Examples 1 to 4, S1×σ+S2×γ<1.8F, a tear defect appeared at the insulating film 202, posing a risk that the battery cell 2 will fall off the housing 1.

[0109] It should be noted that in the above Examples 1 to 10 and Comparative Examples 1 to 4, the test standard "Safety Requirements for Power Batteries for Electric Vehicles" (GB 38031-2020) was used.

[0110] Example 11:

[0111] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 3mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1mm. The coating length L1 of structural adhesive 3 is 350mm. The width W1 of cell housing 201 is 14mm. Therefore, S1 = 2170mm. 2 S2 = 4970mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.5 MPa, and the pull-out strength γ is 2.53 MPa. Therefore, S1×σ+S2×γ=17999.1N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 8646.7N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0112] Example 12:

[0113] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 5.3 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 320 mm. The width W1 of cell housing 201 is 14.5 mm. Therefore, S1 = 3456 mm. 2 S2 = 4704 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.8 MPa, and the pull-out strength γ is 2.75 MPa. Therefore, S1×σ+S2×γ=22612.8N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 10953.1N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0114] Example 13:

[0115] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 5.5 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 310 mm. The width W1 of cell housing 201 is 14.5 mm. Therefore, S1 = 3472 mm. 2 S2 = 4557mm 2Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 3.35 MPa. Therefore, S1×σ+S2×γ=26376.4N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 12827.3N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0116] Example 14:

[0117] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 3mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.12mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.12mm. The coating length L1 of structural adhesive 3 is 250mm. The width W1 of cell housing 201 is 16.2mm. Therefore, S1 = 1560mm. 2 S2 = 4110mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.5 MPa, and the pull-out strength γ is 3.5 MPa. Therefore, S1×σ+S2×γ=19845N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 9570N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0118] Example 15:

[0119] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 5mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.12mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.12mm. The coating length L1 of structural adhesive 3 is 220mm. The width W1 of cell housing 201 is 16.2mm. Therefore, S1 = 2253mm. 2 S2 = 3617mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 3.09 MPa. Therefore, S1×σ+S2×γ=18384.9N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 8850.9N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0120] Example 16:

[0121] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 6mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1mm. The coating length L1 of structural adhesive 3 is 220mm. The width W1 of cell housing 201 is 16.2mm. Therefore, S1 = 2684mm. 2 S2 = 3608mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3 MPa, and the pull-out strength γ is 3.23 MPa. Therefore, S1×σ+S2×γ=19705.8N, and the tensile force F of the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 9539.2N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0122] Example 17:

[0123] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 5mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.11mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.11mm. The coating length L1 of structural adhesive 3 is 240mm. The width W1 of cell housing 201 is 16.2mm. Therefore, S1 = 2453mm. 2 S2 = 3941 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 2 MPa. Therefore, S1×σ+S2×γ=15730.6N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 7565.3N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0124] Example 18:

[0125] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 5mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.15mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.15mm. The coating length L1 of structural adhesive 3 is 200mm. The width W1 of cell housing 201 is 21.8mm. Therefore, S1 = 2060mm. 2 S2 = 4420mm 2Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 2.2 MPa. Therefore, S1×σ+S2×γ=16316N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 7814.8N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0126] Example 19:

[0127] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 8mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.15mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.15mm. The coating length L1 of structural adhesive 3 is 180mm. The width W1 of cell housing 201 is 21.8mm. Therefore, S1 = 2934mm. 2 S2 = 3978 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.6 MPa, and the pull-out strength γ is 2.3 MPa. Therefore, S1×σ+S2×γ=16777.8N, and the tensile force F of the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 8053.6N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0128] Example 20:

[0129] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 7mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.15mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.15mm. The coating length L1 of structural adhesive 3 is 190mm. The width W1 of cell housing 201 is 21.8mm. Therefore, S1 = 2717mm. 2 S2 = 4199 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.8 MPa, and the pull-out strength γ is 2.65 MPa. Therefore, S1×σ+S2×γ=18735N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 9026.1N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0130] Comparative Example 5:

[0131] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 5.3 mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.1 mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.1 mm. The coating length L1 of structural adhesive 3 is 320 mm. The width W1 of cell housing 201 is 14.5 mm. Therefore, S1 = 3456 mm. 2 S2 = 4704 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.8 MPa, and the pull-out strength γ is 2.75 MPa. Therefore, S1×σ+S2×γ=22612.8N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 11453.1N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0132] Comparative Example 6:

[0133] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 3mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.12mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.12mm. The coating length L1 of structural adhesive 3 is 250mm. The width W1 of cell housing 201 is 16.2mm. Therefore, S1 = 1560mm. 2 S2 = 4110mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.5 MPa, and the pull-out strength γ is 3.5 MPa. Therefore, S1×σ+S2×γ=19845N, and the tensile force F of the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 10070N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0134] Comparative Example 7:

[0135] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 5mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.11mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.11mm. The coating length L1 of structural adhesive 3 is 240mm. The width W1 of cell housing 201 is 16.2mm. Therefore, S1 = 2453mm. 2 S2 = 3941 mm 2Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 3.2 MPa, and the pull-out strength γ is 2 MPa. Therefore, S1×σ+S2×γ=15730.6N, and the tensile force F of the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 8065.3N. Simulation analysis and vibration tests along the height direction were performed on the battery pack; the test results are shown in Table 2.

[0136] Comparative Example 8:

[0137] Cell 2 is a blade cell. The coating height H1 of structural adhesive 3 is 8mm. The thickness T1 of insulating film 202 along the height direction of cell housing 201 is 0.11mm. The thickness T4 of insulating film 202 along the thickness direction of cell housing 201 is 0.11mm. The coating length L1 of structural adhesive 3 is 180mm. The width W1 of cell housing 201 is 21.8mm. Therefore, S1 = 2920mm. 2 S2 = 3964 mm 2 Along the height direction of the cell casing 201, the shear strength σ of the bond between the insulating film 202 and the structural adhesive 3 is 2.6 MPa, and the pull-out strength γ is 2.3 MPa. Therefore, S1×σ+S2×γ=16707.2N, and the tensile force F exerted by the bonded portion between the insulating film 202 and the structural adhesive 3 along the height direction of the cell casing 201 is 8553.6N. Simulation analysis and vibration tests along the height direction of the battery pack were performed, and the test results are shown in Table 2.

[0138] Table 2: Test Results of Blade Cells

[0139]

[0140] As can be seen from Table 2, in Examples 11 to 20, the condition S1×σ+S2×γ≥2F is met. During the test, the insulating film 202 and the structural adhesive 3 are well bonded, and the battery cell 2 does not fall off the housing 1.

[0141] In Comparative Examples 5 to 8, S1×σ+S2×γ<2F, a tear defect appears at the insulating film 202, posing a risk that the battery cell 2 will detach from the housing 1.

[0142] It should be noted that in the above Examples 11 to 20 and Comparative Examples 5 to 8, the test standard "Safety Requirements for Power Batteries for Electric Vehicles" (GB 38031-2020) was used.

[0143] 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 and housed in the housing, each battery cell having a battery cell housing, the outer surface of which is covered with an insulating film; Structural adhesive is applied to two opposite sides and the bottom surface of each of the battery cell housings along the thickness direction. The structural adhesive is bonded and fixed to the insulating film to fix each of the battery cells to the housing. Along both sides of the thickness direction of the battery cell casing, the bonding area between the insulating film and the structural adhesive is S1; on the bottom surface of the battery cell casing, the bonding area between the insulating film and the structural adhesive is S2; along the height direction of the battery cell casing, the shear strength of the bond between the insulating film and the structural adhesive is σ, and the pull-out strength is γ; the tensile force F exerted on the bonded portion between the insulating film and the structural adhesive in the height direction of the battery cell casing satisfies S1×σ+S2×γ≥1.8F.

2. The battery pack according to claim 1, characterized in that, The battery cell is a square cell, meeting the 1000mm² requirement. 2 ≤S1≤2500mm 2 6000mm 2 ≤S2≤11000mm 2 , 2.5Mpa≤σ≤3.5Mpa, 2Mpa≤γ≤3.5Mpa.

3. The battery pack according to claim 2, characterized in that, S1 = 2 × (H1 + T1) × L1, where H1 is the coating height of the structural adhesive along the height direction of the battery cell housing on both sides of the thickness direction, T1 is the thickness of the insulating film along the height direction of the battery cell housing, and L1 is the coating length of the structural adhesive, satisfying 3mm ≤ H1 ≤ 6mm, 0.1mm ≤ T1 ≤ 0.15mm, and 130mm ≤ L1 ≤ 270mm.

4. The battery pack according to claim 3, characterized in that, S2 = (W1 + 2T4) × L1, where W1 is the width of the battery cell housing and T4 is the thickness of the insulating film along the thickness direction of the battery cell housing, satisfying 25mm ≤ W1 ≤ 75mm and 0.1mm ≤ T4 ≤ 0.15mm.

5. The battery pack according to claim 1, characterized in that, The battery cell is a blade battery cell, satisfying S1×σ+S2×γ≥2F, 1500mm² 2 ≤S1≤3500mm 2 3500mm 2 ≤S2≤5000mm 2 , 2.5Mpa≤σ≤3.5Mpa, 2Mpa≤γ≤3.5Mpa.

6. The battery pack according to claim 5, characterized in that, S1 = 2 × (H1 + T1) × L1, where H1 is the coating height of the structural adhesive along the height direction of the battery cell housing on both sides of the thickness direction, T1 is the thickness of the insulating film along the height direction of the battery cell housing, and L1 is the coating length of the structural adhesive, satisfying 3mm ≤ H1 ≤ 8mm, 0.1mm ≤ T1 ≤ 0.15mm, and 180mm ≤ L1 ≤ 350mm.

7. The battery pack according to claim 6, characterized in that, S2 = (W1 + 2T4) × L1, where W1 is the width of the battery cell housing and T4 is the thickness of the insulating film along the thickness direction of the battery cell housing, satisfying 14mm ≤ W1 ≤ 25mm and 0.1mm ≤ T4 ≤ 0.15mm.

8. The battery pack according to any one of claims 1 to 7, characterized in that, The surface energy of the insulating film is Y, which satisfies 35mN / m≤Y≤55mN / m.

9. The battery pack according to any one of claims 1 to 7, characterized in that, The adhesive strength of the structural adhesive is R, which satisfies R≥8MPa, and the elongation at break of the structural adhesive is δ, which satisfies δ≥100%.

10. The battery pack according to any one of claims 1 to 7, characterized in that, The thickness of the structural adhesive located between adjacent cell housings is T2, satisfying 0.5mm≤T2≤2mm; And / or, the thickness of the structural adhesive located between the outermost cell housing and the box body is T3, satisfying 0.5mm≤T3≤2mm.

Images