Battery pack and electric device

Abstract

The utility model relates to battery technical field discloses battery pack and electric installation. Battery pack includes: box, a plurality of electric core through structural glue and stick in the box side by side, electric core includes electric core casing and insulating film, the surface of insulating film is undulate, the surface area of any electric core bottom is S1, insulating film is equipped with opening, the area of opening is S2, the bonding surface area between any electric core bottom and structural glue is S1-S2 * K, the sum of bonding surface area of structural glue and the opposite side of electric core is S3, the pull -out strength between second structural glue layer and insulating film is gamma, the shear strength between structural glue and insulating film at electric core bottom is sigma, the shear strength between structural glue and electric core casing is beta, satisfy: 18300N <= [S3 / 2 * gamma + (S1-S2 * K) * sigma + S2 * beta] <= 45000N. Through reasonable limitation relevant parameter, can effectively promote the bonding force between insulating film and structural glue.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a battery pack and an electrical device. 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 (such as blue film), and a cover plate top patch. 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 film mainly covers the outside of the casing, providing external insulation.

[0004] In general, in order to securely assemble multiple cells inside the battery pack, structural adhesive is usually applied between two adjacent cells and between multiple cells and the inner wall of the battery pack, so as to bond and fix the cells inside the battery pack.

[0005] However, during the use of the battery pack, the bonding between the insulating film and the structural adhesive may fail due to insufficient adhesion, thus affecting the long-term reliability of the battery cells. Utility Model Content

[0006] In view of this, the present invention provides a battery pack and power supply device to solve the problem of bonding failure of the insulating film and structural adhesive on the outside of conventional battery cells due to insufficient adhesion.

[0007] In a first aspect, this utility model provides a battery pack, comprising:

[0008] Box;

[0009] Multiple battery cells are bonded side-by-side inside the housing along the X direction using structural adhesive; each battery cell includes a battery cell housing and an insulating film wrapped around the outer surface of the battery cell housing.

[0010] Along the Z-direction of the housing, the surface area of ​​the bottom surface of any of the battery cells is S1; the insulating film on the bottom surface of the battery cell has an opening, the area of ​​which is S2; the surface of the insulating film facing the structural adhesive is wavy; the bonding surface area between the bottom surface of any of the battery cells and the structural adhesive is S1-S2*K.

[0011] The structural adhesive includes a first structural adhesive layer and a second structural adhesive layer. The first structural adhesive layer is located between the bottom surface of the plurality of battery cells and the bottom surface of the housing, and a portion of the first structural adhesive layer is bonded to the battery cell housing through the opening. The second structural adhesive layer is located between two adjacent battery cells and also between the battery cells at both ends and the corresponding inner sidewalls of the housing.

[0012] Along the X direction of the housing, the sum of the bonding surface areas of the second structural adhesive layer and the opposite sides of the battery cell is S3; the pull-out strength of the bond between the second structural adhesive layer and the insulating film is γ, the shear strength of the bond between the first structural adhesive layer and the insulating film is σ, and the shear strength of the bond between the first structural adhesive layer and the battery cell housing is β; S1, S2, S3, γ, β, and σ satisfy the following: 18300N≤[S3 / 2*γ+(S1-S2*K)*σ+S2*β]≤45000N, where K is the ratio of the surface area of ​​the insulating film facing the structural adhesive side to the contour area corresponding to that surface area, and the value range of K is: 1.3≤K≤1.6.

[0013] Beneficial Effects: This invention features a wavy surface on the side of the insulating film facing the structural adhesive, increasing the contact area between the insulating film and the structural adhesive, thus enhancing their adhesion. By creating openings in the insulating film, this invention allows a portion of the first structural adhesive layer to bond directly to the battery cell casing through these openings, providing a double layer of protection for the connection between the structural adhesive and the battery cell. Specifically, the first structural adhesive layer not only bonds indirectly to the battery cell through the insulating film but also directly to the battery cell casing via the openings. This combination of two bonding methods significantly improves the overall reliability of the connection between the first structural adhesive layer and the battery cell. Simultaneously, the second structural adhesive layer forms an effective connection between adjacent battery cells and between the end battery cell and the inner wall of the casing, working in conjunction with the first structural adhesive layer to fix the battery cell from different directions. The range defined by the formula [S3 / 2*γ+(S1-S2*K)*σ+S2*β] ensures that the structural adhesives in each part of the battery pack provide sufficient bonding strength when subjected to external forces such as vibration and impact. This allows the cells to be securely installed in the casing, reducing relative displacement between cells and between cells and the casing. Consequently, it lowers the risk of internal structural damage caused by cell movement, improving the overall safety and lifespan of the battery pack. Furthermore, this design, by rationally allocating the bonding surface area of ​​different structural adhesive layers and utilizing the bonding strength characteristics between different materials, optimizes the amount of structural adhesive used while ensuring connection strength, avoiding unnecessary material waste and achieving a balance between performance and cost.

[0014] In one optional embodiment, the battery cell is a blade battery cell, S1 = W1 * L * K, where W1 is the width of the bottom surface of the battery cell in the X direction of the housing, and the value of W1 is in the range of 15mm ≤ W1 ≤ 25mm; L is the length of the bonding part between the first structural adhesive layer and the battery cell in the Y direction of the housing, and the value of L is in the range of 250mm ≤ L ≤ 380mm.

[0015] Beneficial Effects: For blade-shaped battery cells, this invention quantifies the bonding surface area between the structural adhesive and the battery cell by clearly defining the specific calculation method for S1. This provides a basis for the rational placement and dosage control of the structural adhesive, ensuring that the bonding of the structural adhesive in different parts of the battery cell better conforms to the cell's shape characteristics. Furthermore, by limiting the specific value ranges of W1 and L, the calculation of the bonding surface area can be made more closely aligned with the actual size characteristics of the blade-shaped battery cell. This ensures sufficient bonding surface area between the structural adhesive layer and the battery cell to provide stable adhesion, preventing the battery cell from being poorly fixed due to insufficient area. It also prevents excessive use of structural adhesive due to an excessive bonding surface area, which would increase the weight and cost of the battery pack. Simultaneously, standardized dimensional parameters help improve the consistency of battery pack assembly and production efficiency, further optimizing the overall performance of the battery pack.

[0016] In one optional embodiment, the opening includes a plurality of circular holes spaced apart along the Y direction of the housing, S2 = n*π*W2 2 / 4, where n is the number of the circular holes and is a positive integer greater than or equal to 1; W2 is the diameter of the circular holes, and the value range of W2 is: 7mm≤W2≤15mm.

[0017] Beneficial effects: Setting the openings as circular holes facilitates processing control, resulting in a higher production yield. Furthermore, the insulating film moves smoothly on the conveyor belt during production after the openings are made, leading to higher coating precision. The bonding surface area S2 between the structural adhesive and the cell housing is determined by the number of circular holes n and the diameter W2 of the holes. Controlling W2 within a suitable range means controlling S2 within a suitable range. If S2 is too small, the bonding surface area between the cell housing and the structural adhesive will be small. Further, (S1-S2*K) can be controlled within a suitable range, that is, the bonding surface area between the insulating film and the structural adhesive on the bottom surface of the cell is controlled within a suitable range, ensuring the bonding strength between the insulating film and the structural adhesive on the bottom surface of the cell.

[0018] In one alternative implementation, 0.45 ≤ W2 / W1 ≤ 0.6.

[0019] Beneficial effects: By controlling the value of W2 / W1 within a suitable range, this invention can balance the relative proportions of the opening and the insulating film in the X direction of the housing. If W2 / W1 is too large, the opening will be relatively large and the insulating film will be relatively small, which may easily lead to insulation failure. If W2 / W1 is too small, the opening will be relatively small, making it difficult to effectively improve the fixing and bonding effect.

[0020] In one alternative implementation, 0.14 ≤ S2*K / S1 ≤ 0.25.

[0021] Beneficial effects: By controlling the value of S2*K / S1 within a suitable range, this invention can balance the bonding surface area between the structural adhesive and the insulating film, as well as between the structural adhesive and the battery cell casing. If the value of S2*K / S1 is too large, it means that the area of ​​the opening is too large, which easily leads to the risk of insulation failure. If the value of S2*K / S1 is too small, it means that the bonding surface area between the battery cell casing and the structural adhesive is too small, making it difficult to effectively improve the bonding strength between the two.

[0022] In one optional embodiment, the battery cell is a blade battery cell, S3 = 2 * H * L * K, where H is the height of the second structural adhesive layer in the Z direction of the housing, and the value of H is in the range of 2mm ≤ H ≤ 3.5mm; L is the length of the bonding part between the second structural adhesive layer and the battery cell in the Y direction of the housing, and the value of L is in the range of 250mm ≤ L ≤ 380mm.

[0023] Beneficial effects: This invention quantifies the bonding surface area between the second structural adhesive layer and the battery cell by clearly defining the calculation method of S3 and limiting the value range of H and L. This ensures that the second structural adhesive layer has appropriate height and length in the Z and Y directions, providing sufficient bonding surface area to enhance the stability of the battery cell, while also avoiding increased cost and weight due to excessive use of structural adhesive or excessively large area by standardizing dimensional parameters.

[0024] In one alternative implementation, 3 MPa ≤ σ ≤ 4.5 MPa; and / or, 4.8 MPa ≤ β ≤ 7.5 MPa; and / or, 3 MPa ≤ γ ≤ 4 MPa.

[0025] Beneficial effects: The range of 3 MPa ≤ σ ≤ 4.5 MPa ensures that the shear strength of the bond between the first structural adhesive layer and the insulating film is at a reasonable level, providing stable shear force for the insulating film bond in the (S1-S2*K) section; the setting of 4.8 MPa ≤ β ≤ 7.5 MPa enhances the shear strength of the direct bond between the first structural adhesive layer and the cell casing through the opening, making the direct bond contribution of the S2 section more reliable; while 3 MPa ≤ γ ≤ 4 MPa ensures that the pull-out strength of the bond between the second structural adhesive layer and the insulating film is moderate. The synergistic control of these three parameters avoids both increased material costs due to excessive strength or excessive brittleness after the structural adhesive cures, and prevents insufficient strength from affecting the overall connection stability of the battery pack. Ultimately, this achieves reliable fixation of the battery pack under various operating conditions, improves its vibration and impact resistance, and ensures the long-term safety of the battery pack.

[0026] In one optional embodiment, the surface roughness of the insulating film is Ra, satisfying 1.2μm≤Ra≤2μm.

[0027] Beneficial effects: This utility model controls the surface roughness of the insulating film within a suitable range, which can take into account both the bonding strength and the adhesive filling performance. If Ra is too small, the bonding strength between the insulating film and the structural adhesive is insufficient, and the risk of peeling is easy to occur. If Ra is too large, air bubbles are easy to appear between the insulating film and the structural adhesive, reducing the insulation effect.

[0028] In one optional embodiment, the thickness of the insulating film is T1, which satisfies 0.1mm≤T1≤0.15mm.

[0029] Beneficial effects: This utility model controls the thickness T1 of the insulating film within a suitable range, which can ensure the insulation effect and provide a certain mechanical protection.

[0030] Secondly, this utility model also provides an electrical device, including: a battery pack as described above.

[0031] Beneficial effects: The electrical device of this utility model includes the battery pack as described above, and has all the beneficial technical effects of the battery pack, which will not be repeated here. Attached Figure Description

[0032] 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.

[0033] Figure 1This is a schematic diagram of the structure of a battery cell according to an embodiment of the present utility model;

[0034] Figure 2 for Figure 1 The diagram shows the structure of the insulating film.

[0035] Figure 3 This is a schematic diagram of the structure of a battery pack according to an embodiment of the present utility model;

[0036] Figure 4 for Figure 3 Top view of the battery pack shown;

[0037] Figure 5 for Figure 4 A cross-sectional view from the perspective of angle AA;

[0038] Figure 6 for Figure 3 The diagram shows the structure of the battery pack after one side wall has been removed.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Housing; 2. Structural adhesive; 201. First structural adhesive layer; 202. Second structural adhesive layer; 3. Battery cell; 301. Insulating film; 3011. Opening. Detailed Implementation

[0041] 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.

[0042] To address the problem of bonding failure between the insulating film and structural adhesive on the outside of conventional battery cells due to insufficient adhesion, this utility model provides a battery pack and power supply device.

[0043] The following is combined Figures 1 to 6 The following describes embodiments of the present invention.

[0044] According to embodiments of the present invention, on the one hand, such as Figures 1 to 6 As shown, a battery pack is provided, including: a housing 1 and multiple battery cells 3.

[0045] Specifically, multiple battery cells 3 are bonded side-by-side to the housing 1 along the X direction of the housing 1 using structural adhesive 2. Each battery cell 3 includes a battery cell shell and an insulating film 301 covering the outer surface of the battery cell shell. The surface of the insulating film 301 facing the structural adhesive 2 is wavy. Along the Z direction of the housing 1, the surface area of ​​the bottom surface of any battery cell 3 is S1. The insulating film 301 on the bottom surface of the battery cell 3 has an opening 3011, the area of ​​which is S2. The bonding surface area between the bottom surface of any battery cell 3 and the structural adhesive 2 is S1-S2*K. The structural adhesive 2 includes a first structural adhesive layer 201 and a second structural adhesive layer 202. The first structural adhesive layer 201 is located between the bottom surfaces of the multiple battery cells 3 and the bottom surface of the housing 1, and part of the first structural adhesive layer 201 is bonded to the battery cell shell through the opening 3011. The second structural adhesive layer 202 is located... Between two adjacent cells 3 and between the cells 3 at both ends and the inner sidewalls corresponding to the housing 1; along the X direction of the housing 1, the sum of the bonding surface areas of the second structural adhesive layer 202 and the opposite sides of the cells 3 is S3; the pull-out strength of the bond between the second structural adhesive layer 202 and the insulating film 301 is γ, the shear strength of the bond between the first structural adhesive layer 201 and the insulating film 301 is σ, and the shear strength of the bond between the first structural adhesive layer 201 and the cell shell is β; S1, S2, S3, γ, β, and σ satisfy: 18300N≤[S3 / 2*γ+(S1-S2*K)*σ+S2*β]≤45000N, where K is the ratio of the surface area of ​​the insulating film 301 facing the structural adhesive 2 to the contour area corresponding to that surface area, and the value range of K is: 1.3≤K≤1.6.

[0046] In this embodiment of the invention, the surface of the insulating film 301 facing the structural adhesive 2 is wavy, which increases the contact area between the insulating film 301 and the structural adhesive 2, thereby improving the adhesion between them. By creating a hole 3011 in the insulating film 301, a portion of the first structural adhesive layer 201 can be directly bonded to the battery cell housing through the hole 3011, thus providing dual protection for the connection between the structural adhesive 2 and the battery cell 3. Specifically, the first structural adhesive layer 201 is not only indirectly bonded to the battery cell 3 through the insulating film 301, but also directly bonded to the battery cell housing through the hole 3011. The combination of these two bonding methods significantly improves the overall connection reliability between the first structural adhesive layer 201 and the battery cell 3. Simultaneously, the second structural adhesive layer 202 forms an effective connection between adjacent battery cells 3 and between the end battery cell 3 and the inner wall of the housing 1, cooperating with the first structural adhesive layer 201 to fix the battery cell 3 from different directions. The range defined by the formula [S3 / 2*γ+(S1-S2*K)*σ+S2*β] ensures that the structural adhesive 2 provides sufficient bonding strength for each part of the battery pack when subjected to external forces such as vibration and impact. This allows the battery cells 3 to be securely installed within the housing 1, reducing relative displacement between the battery cells 3 and between the battery cells 3 and the housing 1. This reduces the risk of internal structural damage caused by cell movement, improving the overall safety and lifespan of the battery pack. Furthermore, this design, by rationally allocating the bonding surface area of ​​different structural adhesive 2 layers and utilizing the bonding strength characteristics between different materials, optimizes the amount of structural adhesive 2 used while ensuring connection strength, avoiding unnecessary material waste and achieving a balance between performance and cost.

[0047] It should be noted that, in this embodiment of the invention, the "battery pack" is formed by electrically connecting a certain number of battery cells 3 together and placing them in the housing 1 to protect the battery cells 3 from external impacts, heat, and vibrations. The battery pack contains two or more battery cells 3, the specific number depending on the application of the battery pack and the parameters of a single battery group. In this embodiment of the invention, "battery cell 3" refers to a single battery cell capable of independent charging and discharging. The components of the battery cell 3 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 limitations on the type or shape of the battery cell 3; it can be a blade cell, a square cell, or other types of battery cells 3. The battery cell 3 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 of the battery, 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. Furthermore, in this embodiment, the X direction of the housing is the width direction of housing 1, and the Z direction is the height direction of housing 1.

[0048] It should be noted that the bottom surface area of ​​the battery cell 3 in this embodiment refers to the surface area of ​​the insulating film 301 located on the bottom surface of the battery cell 3 facing the bottom surface of the housing 1 when no opening 3011 is provided.

[0049] Furthermore, since the surface shape of the insulating film 301 facing the structural adhesive 2 is wavy, the surface area of ​​the insulating film 301 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 301 multiplied by its width. After the insulating film 301 wraps around the battery cell 3, the length and width of the insulating film 301 located on a certain side of the battery cell 3 are equal to the length and width of that side of the battery cell 3. In other words, the length and width of the insulating film 301 can be directly measured. K is a coefficient, which is obtained by constructing the shape of the insulating film using a three-dimensional simulation model, calculating its outline area and adhesive surface area, and then dividing the adhesive surface area by the outline area.

[0050] It should be noted that the value of K is also affected by the wave amplitude on the surface of the insulating film and the distance between two adjacent wave peaks. In this invention, the wave amplitude on the surface of the insulating film is 15μm to 40μm, and the distance between two adjacent wave peaks is 120μm to 200μm.

[0051] According to one embodiment of the present invention, such as Figure 5 and Figure 6 As shown, cell 3 is a blade cell, S1 = W1 * L * K, where W1 is the width of the bottom surface of cell 3 in the X direction of the housing, and the value range of W1 is: 15mm ≤ W1 ≤ 25mm; L is the length of the bonding part between the first structural adhesive layer 201 and cell 3 in the Y direction of the housing, and the value range of L is: 250mm ≤ L ≤ 380mm. For blade cells, this embodiment of the invention, by clarifying the specific calculation method of S1, can quantify the bonding surface area between the structural adhesive 2 and cell 3, providing a basis for the reasonable layout and dosage control of the structural adhesive 2, ensuring that the bonding of the structural adhesive 2 at different parts of cell 3 is more in line with the shape characteristics of cell 3. Furthermore, by limiting the specific value ranges of W1 and L, the calculation of the bonding surface area can be made more in line with the actual size characteristics of the blade cell. In this way, it can ensure that there is enough bonding surface area between the structural adhesive layer 2 and the battery cell 3 to provide stable adhesion, avoiding the battery cell 3 being not firmly fixed due to insufficient area. It can also prevent excessive use of structural adhesive layer 2 due to excessive bonding surface area, which would increase the weight and cost of the battery pack. At the same time, standardized dimensional parameters help improve the consistency of battery pack assembly and production efficiency, and further optimize the overall performance of the battery pack.

[0052] It is understood that the value of W1 in this embodiment can be, but is not limited to, 15mm, 16mm, 16.2mm, 17mm, 17.7mm, 18mm, 19mm, 19.5mm, 20mm, 21mm, 21.6mm, 22mm, 23mm, 24mm, and 25mm. The value of L in this embodiment can be, but is not limited to, 250mm, 260mm, 270mm, 295mm, 335mm, 338mm, 342mm, 350mm, 358mm, 365mm, 370mm, and 380mm.

[0053] It should be noted that during the battery pack assembly process, after the structural adhesive 2 comes into contact with the battery cell 3, the structural adhesive 2 will deform under the pressure of the battery cell 3. Since the shape of the structural adhesive 2 after deformation is irregular, in this embodiment, L is an average value to reduce calculation errors. In addition, W1 is the distance between two opposite surfaces of the battery cell 3 in the X direction of the housing, and W1 is the width of the insulating film 301 located on the bottom surface of the battery cell in the X direction of the housing. Furthermore, in this embodiment, the Y direction of the housing is the length direction of the housing 1.

[0054] According to one embodiment of the present invention, such as Figure 1 As shown, the opening 3011 includes multiple circular holes spaced apart along the Y direction of the housing, S2=n*π*W2 2 / 4, where n is the number of circular holes and is a positive integer greater than or equal to 1; W2 is the diameter of the circular hole, and the value of W2 is in the range of 7mm≤W2≤15mm. In this embodiment of the utility model, the opening 3011 is set as a circular hole, which is easy to process and control, has a high production yield, and after the opening 3011, the insulating film 301 moves smoothly during production, and the coating accuracy is high. The bonding surface area S2 between the structural adhesive 2 and the battery cell shell is determined by the number of circular holes n and the diameter of the circular holes W2. Controlling W2 within a suitable range means controlling S2 within a suitable range. If S2 is too small, the bonding surface area between the battery cell shell and the structural adhesive 2 will be small. Further, (S1-S2*K) can be controlled within a suitable range, that is, the bonding surface area between the insulating film 301 and the structural adhesive 2 on the bottom surface of the battery cell 3 is controlled within a suitable range, ensuring the bonding strength between the insulating film 301 and the structural adhesive 2 on the bottom surface of the battery cell 3.

[0055] It is understood that the value of W2 in this embodiment can be, but is not limited to, 7mm, 7.8mm, 8mm, 7.97mm, 8.5mm, 10mm, 11mm, 12mm, 12.8mm, 14mm, and 15mm. The value of L in this embodiment can be, but is not limited to, 250mm, 260mm, 270mm, 295mm, 335mm, 338mm, 342mm, 350mm, 358mm, 365mm, 370mm, and 380mm.

[0056] Furthermore, the number of circular holes can be 12 to 18. The spacing between adjacent circular holes in the Y direction of the housing is 9 mm to 16 mm. Specifically, adaptive adjustments can be made according to design needs, and this utility model does not impose any special limitations on this.

[0057] Understandably, the shape of the opening can also be square or oval, and specific adjustments can be made as needed.

[0058] According to one embodiment of this utility model, 0.45 ≤ W2 / W1 ≤ 0.6. This embodiment of the utility model, by controlling the value of W2 / W1 within a suitable range, can balance the relative proportions of the opening 3011 and the insulating film 301 in the X direction of the housing. If W2 / W1 is too large, the opening 3011 will be relatively large, and the insulating film 301 will be relatively small, easily leading to insulation failure. If W2 / W1 is too small, the opening 3011 will be relatively small, making it difficult to effectively improve the fixing and bonding effect.

[0059] It is understood that the values ​​of W2 / W1 in this embodiment can be, but are not limited to, 0.45, 0.467, 0.48, 0.481, 0.513, 0.556, 0.564, 0.593, and 0.6.

[0060] According to one embodiment of this utility model, 0.14 ≤ S2*K / S1 ≤ 0.25. This embodiment of the utility model, by controlling the value of S2*K / S1 within a suitable range, can balance the bonding surface area between the structural adhesive 2 and the insulating film 301, as well as the bonding surface area between the structural adhesive 2 and the battery cell housing. If the value of S2*K / S1 is too large, it means that the area of ​​the opening 3011 is too large, which easily leads to the risk of insulation failure. If the value of S2*K / S1 is too small, it means that the bonding surface area between the battery cell housing and the structural adhesive 2 is too small, making it difficult to effectively improve the bonding strength between the two.

[0061] It is understood that the value of S2*K / S1 in this embodiment can be, but is not limited to, 0.14, 0.142, 0.154, 0.16, 0.164, 0.172, 0.191, 0.214, 0.223, 0.224, 0.241, 0.245, and 0.25.

[0062] According to one embodiment of the present invention, such as Figure 5 and Figure 6As shown, cell 3 is a blade cell, and S3 = 2*H*L*K, where H is the height of the second structural adhesive layer 202 in the Z direction of the housing, and the value of H is in the range of 2mm≤H≤3.5mm; L is the length of the bonding part between the second structural adhesive layer 202 and cell 3 in the Y direction of the housing, and the value of L is in the range of 250mm≤L≤380mm. This embodiment of the invention quantifies the bonding surface area between the second structural adhesive layer 202 and cell 3 by clearly defining the calculation method of S3 and limiting the value range of H and L. In this way, it ensures that the second structural adhesive layer 202 has a suitable height and length in the Z and Y directions, providing sufficient bonding surface area to enhance the fixing stability of cell 3, and also avoids increased cost and weight due to excessive use or excessive area of ​​structural adhesive 2 by standardizing dimensional parameters.

[0063] It is understood that the value of H in this embodiment can be, but is not limited to, 2mm, 2.1mm, 2.2mm, 2.3mm, 2.5mm, 2.8mm, 3.1mm, 3.23mm, and 3.5mm. The value of L in this embodiment can be, but is not limited to, 250mm, 260mm, 270mm, 295mm, 335mm, 338mm, 342mm, 350mm, 358mm, 365mm, 370mm, and 380mm.

[0064] It should be noted that during the battery pack assembly process, after the structural adhesive 2 comes into contact with the battery cell 3, the structural adhesive 2 will deform under the pressure of the battery cell 3. Since the shape of the structural adhesive 2 after deformation is irregular, in order to reduce calculation errors, L and H in this embodiment are both average values.

[0065] According to one embodiment of this utility model, 3 MPa ≤ σ ≤ 4.5 MPa; and / or 4.8 MPa ≤ β ≤ 7.5 MPa; and / or 3 MPa ≤ γ ≤ 4 MPa. Specifically, the range of 3 MPa ≤ σ ≤ 4.5 MPa ensures that the shear strength of the bond between the first structural adhesive layer 201 and the insulating film 301 is at a reasonable level, so that the bonding of the insulating film 301 in the (S1-S2*K) portion can provide stable shear force; the setting of 4.8 MPa ≤ β ≤ 7.5 MPa strengthens the shear strength of the direct bonding between the first structural adhesive layer 201 and the cell housing through the opening 3011, making the direct bonding contribution of the S2 portion more reliable; while 3 MPa ≤ γ ≤ 4 MPa ensures that the pull-out strength of the bond between the second structural adhesive layer 202 and the insulating film 301 is moderate. The coordinated control of these three parameters avoids both excessive material costs due to excessive strength or excessive brittleness after the structural adhesive 2 has cured, and prevents insufficient strength from affecting the overall connection stability of the battery pack. Ultimately, this achieves reliable fixation of the battery pack under various working conditions, improves its vibration and impact resistance, and ensures the long-term safety of the battery pack.

[0066] It is understood that in this embodiment, the value of σ can be, but is not limited to, 3 MPa, 3.1 MPa, 3.2 MPa, 3.25 MPa, 3.4 MPa, 3.5 MPa, 3.6 MPa, 3.8 MPa, 3.9 MPa, 4 MPa, 4.1 MPa, 4.2 MPa, 4.4 MPa, and 4.5 MPa. The value of β can be, but is not limited to, 4.8 MPa, 4.9 MPa, 5 MPa, 5.3 MPa, 6.1 MPa, 6.4 MPa, and 7.5 MPa. The value of γ can be, but is not limited to, 3 MPa, 3.1 MPa, 3.2 MPa, 3.25 MPa, 3.4 MPa, 3.5 MPa, 3.6 MPa, 3.8 MPa, and 4 MPa.

[0067] According to one embodiment of the present invention, such as Figure 1 As shown, the outer surface of the insulating film 301 is provided with a frosted reinforcing layer, which includes a frosted mesh layer or a frosted stripe layer. In this embodiment of the invention, the surface of the insulating film 301 is treated with processes such as sandblasting to form a frosted reinforcing layer, that is, to form a micro-uneven structure, which can improve the surface roughness of the insulating film 301, thereby increasing the effective bonding surface area between the insulating film 301 and the structural adhesive 2, and increasing the connection strength.

[0068] It should be noted that the grid can be square, triangular, diamond, circular, or irregularly shaped. The shapes of the grids can be the same or different. The depths of the grids can be the same or different. When the outer surface of the insulating film 301 is striped, the stripes can be straight or curved. The shapes and depths of the stripes can be the same or different. When the stripes are straight, they can be parallel to the length direction of the battery cell 3 or at an angle to the length direction of the battery cell 3, i.e., oblique stripes.

[0069] According to one embodiment of the present invention, the surface roughness of the insulating film 301 is Ra, satisfying 1.2μm≤Ra≤2μm. This embodiment of the present invention controls the surface roughness of the insulating film 301 within a suitable range, balancing bonding strength and adhesive filling performance. If Ra is too small, the bonding strength between the insulating film 301 and the structural adhesive 2 is insufficient, easily leading to a risk of peeling. If Ra is too large, air bubbles are easily formed between the insulating film 301 and the structural adhesive 2, reducing the insulation effect.

[0070] It is understood that in this embodiment, the surface roughness Ra of the substrate layer can be, but is not limited to, 1.05μm, 1.1μm, 1.15μm, 1.2μm, 1.25μm, 1.3μm, 1.35μm, 1.4μm, 1.45μm, and 1.5μm.

[0071] It should be noted that the roughness Ra is measured using the Tokyo Seimitsu roughness tester via a stylus method. Specifically, during measurement, the diamond stylus on the sensor maintains perpendicular contact with the surface being measured (the outer surface of the insulating film 301), and the sensor is dragged at a constant speed by a driver. The contour peaks and valleys of the surface being measured cause the stylus to move up and down. This displacement is synchronized with the magnetic core of the fulcrum, thereby changing the inductance of the differential inductor coil, and thus the roughness Ra is measured.

[0072] According to one embodiment of the present invention, the thickness of the insulating film 301 is T1, which satisfies 0.1mm ≤ T1 ≤ 0.15mm. This embodiment of the present invention controls the thickness T1 of the insulating film 301 within a suitable range, ensuring insulation effectiveness and providing a certain degree of mechanical protection.

[0073] It should be noted that the thickness T1 of the insulating film 301 in this embodiment is the remaining thickness after removing the structural adhesive 2 (the amount of adhesive is small and can be ignored) that fills the trough of the wave.

[0074] According to an embodiment of the present invention, in another aspect, the present invention also provides an electrical device, including a battery pack as described above. The electrical device of this embodiment includes the battery pack as described above, and possesses all the beneficial technical effects of the battery pack, which will not be repeated here.

[0075] It should be noted that electrical devices can include vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys, and power tools, etc. Vehicles can be gasoline-powered cars, natural gas-powered cars, or new energy vehicles; new energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. Spacecraft include airplanes, rockets, space shuttles, and spacecraft, etc. Electric toys include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Power tools include metal cutting power tools, grinding power tools, assembly power tools, and railway power tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators, and electric planers, etc. This application does not impose any special limitations on the above-mentioned electrical devices.

[0076] Taking a vehicle as an example, the battery pack inside the vehicle can be located at the bottom, front, or rear of the vehicle. The battery pack can be used to power the vehicle, for example, as its operating power source. The vehicle may also include a controller and a motor. The controller controls the battery pack to supply power to the motor, for example, to meet the vehicle's power needs during starting, navigation, and driving. In some embodiments of this application, the battery pack can not only serve as the vehicle's operating power source but also as its driving power source, replacing or partially replacing fuel or natural gas to provide propulsion for the vehicle.

[0077] The technical effects of this utility model will be illustrated below with reference to specific embodiments and comparative examples.

[0078] Table 1: Cell 3 in both the example battery pack and the comparative battery pack are blade cells, and the test standard is: "Safety Requirements for Power Batteries for Electric Vehicles" (GB38031-2020).

[0079] Table 1

[0080]

[0081]

[0082] As can be seen, in the battery packs of Examples 1 to 10, after simulation analysis and vibration testing, the insulating film 301 did not exhibit tearing problems, and the insulating film 301 and structural adhesive 2 were not easily separated. In contrast, in the battery packs of Comparative Examples 1 and 2, after simulation analysis and vibration testing, tearing problems occurred at the insulating film 301, and the insulating film 301 and structural adhesive 2 easily separated. The reason for this problem in the battery pack of Comparative Example 1 is that [S3 / 2*γ+(S1-S2*K)*σ+S2*β] is too small, resulting in insufficient bonding strength; the reason for this problem in the battery pack of Comparative Example 2 is that H is too small, resulting in insufficient bonding strength. In the battery pack of Comparative Example 3, after simulation analysis and vibration testing, no tearing problems occurred at the insulating film 301, and the insulating film 301 and structural adhesive 2 were not easily separated. However, the [S3 / 2*γ+(S1-S2*K)*σ+S2*β] in the battery pack of Comparative Example 3 is too large, resulting in excessive adhesive application and increased cost. It should be noted that during the test, the battery cell 3 of the battery pack needs to be subjected to a force in the X direction. Furthermore, the insulating film 301 covering the battery cell 3 in the battery packs corresponding to the embodiments and comparative examples in the table above is the same; that is, the wave amplitude on the surface of the insulating film 301 facing the structural adhesive 2 and the spacing between two adjacent wave peaks are the same. Therefore, the value of K is the same in all embodiments and comparative examples. Specifically, the value of K in the table above is 1.3.

[0083] It should be noted that in this embodiment, γ, σ, and β along the X direction of the housing can be obtained using measuring tools such as a universal tensile testing machine. The testing standard for γ is GB / T6329, and the testing standards for σ and β are GB / T7124.

[0084] Taking the shear strength σ of the bond between insulating film 301 and structural adhesive 2 as an example, the process of obtaining its specific value using a universal tensile testing machine is as follows:

[0085] Shear specimens were prepared according to GB / T7124. Two 100mm × 25mm × 2mm shear specimens were cut. Structural adhesive 2 was applied to one side of the insulating film 301 of both shear specimens, with a bonding area of ​​25mm × 25mm between the insulating film 301 and the structural adhesive 2. The two shear specimens were then fixed together. Al3003 test pieces were used for the shear specimens, and PET film was used for the insulating film 301. The shear specimens were repeatedly rolled with a 2kg roller at least five times and then left to stand at room temperature (23±2℃) for 24 hours. Testing then began. The two bonded shear specimens were fixed to fixtures, and a universal tensile testing machine was used to stretch the upper end of one shear specimen and the lower end of the other at a stretching speed of 50mm / min. The stress on the shear specimen was divided by the bonding surface area of ​​25mm × 25mm to obtain the shear strength σ.

[0086] Taking the tensile strength γ of the bond between the insulating film 301 and the second structural adhesive layer 202 as an example, the process of obtaining its specific value using a universal tensile testing machine is as follows:

[0087] The pull-out test specimens were prepared according to GB / T6329. Two 100mm×25mm×2mm pull-out test specimens were cut. Structural adhesive 2 was applied to one side of the insulating film 301 of both specimens, with a bonding area of ​​25mm×25mm between the insulating film 301 and the structural adhesive 2. The two specimens were then fixed together. Al3003 test pieces were used for the pull-out test specimens, and PET film was used for the insulating film 301. 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. Testing then began. The two bonded pull-out test specimens were fixed to fixtures, and a universal tensile testing machine was used to stretch the upper surface of one shear specimen and the lower surface of the other 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 surface area of ​​25mm×25mm.

[0088] 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 bonded side-by-side inside the housing along the X direction of the housing using structural adhesive; each battery cell includes a battery cell housing and an insulating film wrapped around the outer surface of the battery cell housing; the surface of the insulating film facing the structural adhesive is wavy. Along the Z-direction of the housing, the surface area of ​​the bottom surface of any of the battery cells is S1; the insulating film on the bottom surface of the battery cells has an opening, the area of ​​which is S2; the bonding surface area between the bottom surface of any of the battery cells and the structural adhesive is S1-S2*K. The structural adhesive includes a first structural adhesive layer and a second structural adhesive layer. The first structural adhesive layer is located between the bottom surface of the plurality of battery cells and the bottom surface of the housing, and a portion of the first structural adhesive layer is bonded to the battery cell housing through the opening. The second structural adhesive layer is located between two adjacent battery cells and also between the battery cells at both ends and the corresponding inner sidewalls of the housing. Along the X direction of the housing, the sum of the bonding surface areas of the second structural adhesive layer and the opposite sides of the battery cell is S3; the pull-out strength of the bond between the second structural adhesive layer and the insulating film is γ, the shear strength of the bond between the first structural adhesive layer and the insulating film is σ, and the shear strength of the bond between the first structural adhesive layer and the battery cell housing is β; S1, S2, S3, γ, β, and σ satisfy the following: 18300N≤[S3 / 2*γ+(S1-S2*K)*σ+S2*β]≤45000N, where K is the ratio of the surface area of ​​the insulating film facing the structural adhesive side to the contour area corresponding to that surface area, and the value range of K is: 1.3≤K≤1.

6.

2. The battery pack according to claim 1, characterized in that, The battery cell is a blade battery cell, S1 = W1 * L * K, where W1 is the width of the bottom surface of the battery cell in the X direction of the housing, and the value range of W1 is: 15mm ≤ W1 ≤ 25mm; L is the length of the part of the first structural adhesive layer that is attached to the battery cell in the Y direction of the housing, and the value range of L is: 250mm ≤ L ≤ 380mm.

3. The battery pack according to claim 2, characterized in that, The opening includes a plurality of circular holes spaced apart along the Y direction of the housing, S2 = n*π*W2 2 / 4, where n is the number of the circular holes and is a positive integer greater than or equal to 1; W2 is the diameter of the circular holes, and the value range of W2 is: 7mm≤W2≤15mm.

4. The battery pack according to claim 3, characterized in that, 0.45≤W2 / W1≤0.

6.

5. The battery pack according to claim 3, characterized in that, 0.14≤S2*K / S1≤0.

25.

6. The battery pack according to claim 1, characterized in that, The battery cell is a blade battery cell, S3 = 2 * H * L * K, where H is the height of the second structural adhesive layer in the Z direction of the housing, and the value of H is in the range of 2mm ≤ H ≤ 3.5mm; L is the length of the part of the second structural adhesive layer that is attached to the battery cell in the Y direction of the housing, and the value of L is in the range of 250mm ≤ L ≤ 380mm.

7. The battery pack according to any one of claims 1 to 6, characterized in that, 3 MPa ≤ σ ≤ 4.5 MPa; and / or 4.8 MPa ≤ β ≤ 7.5 MPa; and / or 3 MPa ≤ γ ≤ 4 MPa.

8. The battery pack according to any one of claims 1 to 6, characterized in that, The surface roughness of the insulating film is Ra, which satisfies 1.2μm≤Ra≤2μm.

9. The battery pack according to any one of claims 1 to 6, characterized in that, The thickness of the insulating film is T1, which satisfies 0.1mm≤T1≤0.15mm.

10. An electrical appliance, characterized in that, include: The battery pack as described in any one of claims 1 to 9.

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