Insulating film structure, battery cell and battery pack

Abstract

This utility model relates to the field of battery technology and discloses an insulating film structure, a battery cell, and a battery pack. The insulating film structure includes a film substrate with several rows of through holes. After the film monomer covers the outer surface of the battery cell's casing, a gap is formed between the first and second sides of the film monomer on the terminal side. The portions of the casing corresponding to the through holes and the gap on the terminal side can be exposed and bonded to the adhesive, increasing the bonding strength between the adhesive and the battery cell. Furthermore, by limiting the center distance between two adjacent rows of through holes on the film substrate along the first direction to satisfy the relationship C-W1-L2 / L1×4.5≤W≤C-W1-L2 / L1×3.5, a reasonable spacing is achieved between two adjacent rows of through holes on the film substrate. This ensures that the film monomer has sufficient coverage area on the casing, guaranteeing the insulation and withstand voltage of the battery cell, and also ensures sufficient spacing between the first and second sides, guaranteeing the bonding strength between the battery cell and the adhesive.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to insulating film structure, battery cell and battery pack. Background Technology

[0002] A battery cell comprises a cover plate, a casing, electrode assembly, and an insulating film. The cover plate and casing are welded together to form a sealed space protecting the electrode assembly. The insulating film covers the outside of the casing, providing external insulation for the battery cell. The outer surface of the insulating film is bonded to the battery pack housing using structural adhesive. Blue insulating tape is widely used as an insulating film for battery cell casing insulation due to its low cost and mature coating process and equipment. Currently, a common approach is to add openings to the insulating film to allow parts of the casing to be directly bonded to the adhesive, thereby improving the bonding strength between the battery cell and the battery pack housing.

[0003] However, the insulating film covering a single cell is cut from a whole roll of film material. Through holes are directly processed into the uncut film material. The cut insulating film is then wrapped around the outside of the casing. The position of the through hole in the insulating film serves as the starting surface, and a gap is formed between the two sides of the ending side. Because it needs to be stretched during the wrapping process, it deforms and elongates, resulting in the following problems: the width of the gap on the ending side after the cell is wrapped is either large or small, and the edge deviation is large, which easily leads to a high rate of insulation withstand voltage failure after the cell is wrapped; because the gap width on the ending side is unstable, it affects the bonding area between the cell casing and the box, thus making the bonding strength between the cell and the box unstable, and the overall structural strength of the battery pack unstable. Utility Model Content

[0004] In view of this, the present invention provides an insulating film structure, a battery cell, and a battery pack to solve the problems of high insulation withstand voltage failure rate and unstable bonding strength between the battery cell and the casing after the battery cell is coated.

[0005] In a first aspect, this utility model provides an insulating film structure, comprising: a film substrate having a plurality of rows of through holes spaced apart along a first direction, each row of through holes including a plurality of through holes spaced apart along a second direction, the center distance between two adjacent rows of through holes along the first direction being W, the dimension of the film substrate along the second direction being L1, and the sum of the opening dimensions of the plurality of through holes in each row along the second direction being L2; the film substrate is adapted to be cut into a plurality of film monomers arranged along the first direction, each film monomer having a row of through holes. The through-hole is provided. The membrane monomer forms a first side and a second side on both sides along the first direction. Each membrane monomer is adapted to cover the outer peripheral surface of a shell. The perimeter of the outer peripheral surface of the shell is C. After the membrane monomer is covered on the shell, the first side and the second side are spaced apart, and the preset distance between the first side and the second side is W1. The relationship between W and C, W1, L1, L2 is: C-W1-L2 / L1×4.5≤W≤C-W1-L2 / L1×3.5.

[0006] Beneficial effects: By creating several rows of through holes on the membrane substrate, and each membrane unit cut from the membrane substrate having one row of through holes, and after the membrane unit is wrapped around the outer surface of the battery cell housing, a gap is formed between the first and second sides of the membrane unit at the tail end. This allows the portions of the housing corresponding to the through holes and the portions corresponding to the gaps on the tail end to be exposed and bonded to the adhesive. This ensures adhesion between the insulating film and the adhesive while increasing direct bonding between part of the housing and the adhesive, thus increasing the bonding strength between the adhesive and the battery cell. Furthermore, by limiting the center distance W between two adjacent rows of through holes on the membrane substrate along the first direction, the preset distance W1 between the first and second sides of the wrapped membrane unit, and the dimension L of the membrane substrate along the second direction... 1. The sum of the opening dimensions L2 of multiple through holes in each column along the second direction satisfies the relationship C-W1-L2 / L1×4.5≤W≤C-W1-L2 / L1×3.5. This relates W to the ratio of the total opening length along the first direction on the membrane unit to the length of the membrane unit, ensuring a reasonable spacing between adjacent columns of through holes on the membrane substrate. This, in turn, ensures that the membrane unit has a reasonable size along the first direction. After the membrane unit is wrapped around the battery cell, it can ensure that the membrane unit has sufficient coverage area on the shell, thereby ensuring the insulation and withstand voltage performance of the battery cell. It can also ensure sufficient spacing between the first side and the second side, thereby ensuring the bonding strength between the battery cell and the adhesive, and thus ensuring the structural strength and stability of the battery pack.

[0007] In one optional embodiment, the sum of the opening dimensions L2 of the plurality of through holes in each column along the second direction satisfies the relationship L1 of the membrane substrate along the second direction as follows: 0.5≤L2 / L1≤0.8.

[0008] Beneficial effects: By limiting the value of L2 / L1 to the range of 0.5 to 0.8, the total opening length of all through holes on the membrane cell along the second direction has a reasonable proportion on the membrane cell. This ensures that the through holes can provide sufficient contact area between the shell and the adhesive, and also ensures that the gap on the end side can provide sufficient contact area between the shell and the adhesive. This ensures the bonding strength between the two first sides of the shell and the adhesive, avoids the failure of the bonding between the cell and the adhesive, and thus ensures the overall stability of the battery pack.

[0009] In one optional embodiment, the dimension L1 of the membrane substrate along the second direction is in the range of 400mm≤L1≤600mm.

[0010] Beneficial effects: It can ensure that the membrane monomer can cover the outer surface of the shell well, ensuring the insulation of the outer surface of the cell shell, thereby improving the safety of the cell, while avoiding material waste, saving costs, and improving processing and production efficiency.

[0011] In one optional implementation, along the second direction, the distance between two adjacent through holes is B, wherein the value of B is in the range of B≥8mm;

[0012] And / or, along the first direction, the distance from the center point of the through hole to the first side is equal to W / 2, and the distance from the center point of the through hole to the second side is equal to W / 2.

[0013] Beneficial effects: By limiting B to greater than or equal to 8mm, sufficient distance can be ensured between two adjacent through holes on the membrane unit along the second direction, thereby avoiding excessive stretching deformation of the insulating film along the first direction during the film-making process. This ensures that the gap between the first and second sides after film-making has sufficient width, thereby ensuring that the shell can bond with the adhesive through the gap and with sufficient bonding area, ensuring bonding strength, preventing the battery cell from detaching from the housing due to bonding failure, and ensuring the centering of the gap on the first side, thus improving film accuracy.

[0014] And / or, by defining the distance from the center point of the through hole to the first side as equal to the distance to the second side, and both being W / 2, the membrane monomer is formed by cutting along the symmetrical line between two adjacent rows of through holes on the membrane substrate. This facilitates processing control, simplifies the process, increases production efficiency, and ensures the symmetry of the membrane monomer. It also ensures that the edge distance from the first side to the first side on the tail side is equal to the edge distance from the second side to the first side, thereby ensuring the centering of the gap formed between the first side and the second side on the first side, guaranteeing film precision, and improving production yield.

[0015] In one alternative embodiment, the opening shape of the through hole is circular or polygonal.

[0016] Beneficial effects: The through hole is a round hole, and the opening process of a round hole is easy to control, which helps to improve production efficiency; by setting the opening shape of the through hole to be polygonal, it can also be ensured that the through hole has sufficient opening area, thereby ensuring that the shell can be bonded to the adhesive through the through hole.

[0017] Secondly, this utility model also provides a battery cell, comprising: a housing; and a membrane unit cut from the aforementioned insulating film structure, wherein the membrane unit covers the outer peripheral surface of the housing. Since the battery cell includes a membrane unit cut from the insulating film structure and has the same effects as the insulating film structure, it will not be described further here.

[0018] In one optional embodiment, the housing has two first side surfaces arranged opposite each other along the Z direction, the first side surface and the second side surface are located on the same first side surface, the width dimension of the first side surface along the X direction is W0, the single-sided edge width of the membrane monomer on the first side surface is W2, and the preset distance W1 between the first side surface and the second side surface satisfies the following relationship with the width dimension W0 of the first side surface along the X direction and the single-sided edge width W2 of the membrane monomer on the first side surface: W1=W0-2×W2, where W2≥1.5mm.

[0019] Beneficial effect: It can ensure that the insulating film has sufficient coverage area on the first side, thereby ensuring the insulation of the outer surface of the battery cell.

[0020] In one optional embodiment, the length of the housing along the Y direction is L0, and the value of L0 is in the range of 400mm≤L0≤600mm;

[0021] And / or, the total thickness of the shell along the X direction is W0, and the value of W0 is in the range of 15mm≤W0≤30mm;

[0022] And / or, the height of the housing along the Z direction is H0, and the value of H0 is in the range of 80mm≤H0≤130mm.

[0023] Beneficial effects: By limiting L0 to a value between 400mm and 600mm, the casing has a reasonable length, which can ensure that the battery cell has sufficient capacity and that the casing can be smoothly processed and formed.

[0024] And / or, by limiting W0 to a value between 15mm and 30mm, it is possible to ensure that the battery cell has sufficient capacity and improve the battery cell production efficiency, while also avoiding excessive heat generation during battery cell use and ensuring the thermal safety performance of the battery cell.

[0025] And / or, by limiting H0 to a value between 80mm and 130mm, it is possible to ensure that the cell has sufficient capacity while avoiding the cell and battery pack occupying too much space along the Z direction, thus facilitating the installation and arrangement of the cell and battery pack.

[0026] Thirdly, this utility model also provides a battery pack, comprising: a housing; and the aforementioned battery cell, wherein the battery cell is disposed within the housing. Since the battery pack includes the battery cell and has the same effect as the battery cell, it will not be described further here.

[0027] In one optional embodiment, the battery pack further includes an adhesive, which is disposed at least at both ends of the battery cell along the Z direction between the battery cell and the housing. The adhesive includes a main body and a filler portion. The main body is bonded to the outer surface of the membrane cell, and the filler portion fills the through holes and the gap between the first side and the second side, and the filler portion is partially bonded to the housing.

[0028] Beneficial effects: By applying adhesive between the battery cell and the housing, the battery cell is bonded and fixed inside the housing, and the adhesive is also bonded to the inner wall of the housing. At the same time, the main part of the adhesive is bonded to at least a portion of the outer surface of the membrane unit, and the filling part is squeezed into the through hole and the receiving space between the first side and the second side. Thus, the parts of the housing corresponding to the through hole and the receiving space are directly bonded to the adhesive, improving the bonding strength between the adhesive and the battery cell, thereby further ensuring the relative stability of the battery cell and the housing. Attached Figure Description

[0029] 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.

[0030] Figure 1 This is a schematic diagram of the state of a roll of film substrate during the unfolding process according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of a membrane substrate according to an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of the structure of another membrane substrate according to an embodiment of the present invention;

[0033] Figure 4 for Figure 3 A magnified view of part A in the diagram;

[0034] Figure 5 This is a schematic diagram of the structure of a membrane monomer according to an embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram of the structure of a bare battery cell according to an embodiment of the present utility model;

[0036] Figure 7 This is a schematic diagram of the structure of a membrane monomer being coated onto a bare battery cell according to an embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of the structure of a battery cell after the membrane monomer is coated onto the bare battery cell, according to an embodiment of the present invention.

[0038] Figure 9 for Figure 8 A magnified view of a portion of the middle section near the cover plate;

[0039] Figure 10 for Figure 8 The diagram shows a structural schematic of the battery cell from another perspective.

[0040] Figure 11 This is a schematic diagram of the structure of a battery cell after the membrane monomer is coated onto a bare battery cell, according to another embodiment of this utility model.

[0041] Figure 12 This is an exploded view of the battery cell before the improvement.

[0042] Figure 13 for Figure 12 A magnified view of a portion of the battery cell near the cover plate;

[0043] Figure 14 This is a schematic diagram of the membrane substrate before the improvement.

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

[0045] 1. Membrane substrate; 101. Through hole; 110. Membrane monomer; 111. First side edge; 112. Second side edge;

[0046] 2. Battery cell; 201. Cover plate; 202. Electrode group; 203. Electrode group end plate; 204. Bare battery cell insulating sheet; 205. Top cover patch; 210. Housing; 211. First side; 212. Second side. Detailed Implementation

[0047] 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.

[0048] Lithium-ion battery cells, as a commonly used type of battery cell, are widely used in various fields such as transportation power supplies, power storage power supplies, new energy storage power supplies, and aerospace and military industries due to their advantages such as large capacity, high operating voltage, strong charge retention capability, and long cycle life. A battery cell includes: a cover plate 201, a housing 210, electrode groups 202, electrode group end plates 203, bare cell insulating sheets 204, an insulating film, and a top cover patch 205. The cover plate 201 and the housing 210 are welded together to form a sealed space protecting the electrode groups 202. The bare cell insulating sheets 204 cover the electrode groups 202 to protect them and prevent short circuits caused by contact between the electrode groups 202 and the housing 210. The electrode group end plates 203 are used to fix the tabs of the electrode groups 202 and provide space to protect the tabs. The insulating film mainly covers the outside of the housing 210, achieving external insulation of the battery cell housing. Blue insulating tape is commonly used as the insulating film due to its advantages of low cost, mature coating process, and equipment. Blue insulating tape is currently widely used in the field of lithium battery casing insulation protection. The advantages of blue insulating tape, such as low cost and mature coating process and equipment, make it widely used as an insulating film for the insulation protection of battery cell casings.

[0049] However, the main structure of the blue insulating tape is PET (polyethylene terephthalate) film + pressure-sensitive adhesive, with a thickness generally around 70μm-110μm, resulting in relatively low adhesion. In today's era of rapid development in CTP and CTC technologies, the insulating film of cell 2 is directly fixed to the upper and lower boxes of the PACK using adhesive. During mechanical vibration / impact tests of the entire package, adhesion failure and detachment of the blue film often occur. Therefore, a common solution is to add openings to the insulating film on the adhesive bonding surface between the cell and the battery pack. This allows for direct bonding of parts of the casing to the adhesive, improving the bonding strength between the cell and the battery pack box.

[0050] Research has revealed that because the insulating film covering a single battery cell is cut from a whole roll of film substrate 1, several rows of through holes are directly processed on the uncut film substrate 1. The cut film unit 110 is then wrapped around the outside of the casing. The position where the through holes are opened on the insulating film serves as the starting surface, and a gap is formed between the two sides of the ending side. Because it needs to be stretched and deformed during the wrapping process, the opening of the insulating film is prone to the following problems: Due to the unreasonable design of the spacing between two adjacent rows of through holes, the width of the gap on the ending side after the battery cell is wrapped is either too large or too small. The large deviation of the edge distance of this gap can easily lead to a high rate of insulation withstand voltage failure after the battery cell is wrapped. In addition, the unstable gap width on the ending side affects the bonding area between the battery cell casing and the box, thereby making the bonding strength between the battery cell and the box unstable, and the overall structural strength of the battery pack unstable.

[0051] The following is combined with Figures 1 to 14 The following describes embodiments of the present invention.

[0052] According to embodiments of the present invention, in one aspect, an insulating film structure is provided, such as... Figures 1 to 5 As shown, the insulating film structure includes: a film substrate 1, which has a plurality of rows of through holes 101 spaced apart along a first direction, each row of through holes 101 including a plurality of through holes 101 spaced apart along a second direction, the center distance between two adjacent rows of through holes 101 along the first direction being W, the dimension of the film substrate 1 along the second direction being L1, and the sum of the opening dimensions of the plurality of through holes 101 in each row along the second direction being L2; the film substrate 1 is adapted to be cut into a plurality of film monomers 110 arranged along the first direction, each film monomer 110 having a row of through holes 101, and the film monomer 1 10 forms a first side 111 and a second side 112 on both sides along a first direction. Each membrane monomer 110 is suitable for covering the outer peripheral surface of a housing 210. The perimeter of the outer peripheral surface of the housing 210 is C. After the membrane monomer 110 covers the housing 210, the first side 111 and the second side 112 are spaced apart, and the preset distance between the first side 111 and the second side 112 is W1. W satisfies the following relationship with C, W1, L1, and L2: C - W1 - L2 / L1 × 4.5 ≤ W ≤ C - W1 - L2 / L1 × 3.5. Here, the first direction refers to... Figures 2 to 5 The "first direction" indicated by the middle arrow, the second direction refers to... Figures 2 to 5 The "second direction" indicated by the middle arrow; the first direction intersects with the second direction, preferably, the first direction is perpendicular to the second direction; the units of W, C, W1, L1, and L2 are all mm.

[0053] It should be noted that each column of through holes 101 has a center line extending along the second direction (e.g., Figures 2 to 3As shown), the center distance W between two adjacent columns of through holes 101 along the first direction refers to the vertical distance between the center lines of the two adjacent columns of through holes 101; further combined with Figure 6 As shown, Figure 6 The image shows a bare battery cell without membrane-coated monomer 110. The housing 210 of the bare battery cell has two first side surfaces 211 arranged opposite each other along the Z direction, and two second side surfaces 212 arranged opposite each other along the X direction. That is, the outer peripheral surface of the housing 210 includes two first side surfaces 211 and two second side surfaces 212. The width dimension of the first side surface 211 along the X direction is W0, and the dimension of the second side surface 212 along the Z direction is H0. Then, the perimeter C of the outer peripheral surface of the housing 210 is 2×(H0+W0)-W1. The dimension W0 of the first side surface 211 along the X direction is smaller than the dimension of the second side surface 212 along the Z direction. During the battery cell coating process, the opening area on the membrane monomer 110 is first pasted onto one of the first side surfaces 211, and then the membrane monomer 110 is flipped up onto the second side surfaces 212 on both sides. Fold and paste, and finally finish on another first side 211 (as the finishing side). The side of the membrane unit 110 extending along the first direction surrounds the outer peripheral surface of the shell 210. The first side 111 and the second side 112 are both located on the first side 211 of the finishing side, and the first side 111 and the second side 112 do not overlap. A gap is formed between the first side 111 and the second side 112 on the outer surface of the shell 210. W1 is the preset distance between the first side 111 and the second side 112 along the X direction. The preset distance refers to the theoretical distance set in advance when the membrane unit 110 is not stretched and deformed. The shell part exposed at the gap between the first side 111 and the second side 112 and the shell part corresponding to the through hole 101 can be bonded to the box with adhesive.

[0054] Further integration Figures 6 to 11 As shown, the second direction of the membrane substrate 1 is parallel to the Y direction of the battery cell, further bonding... Figure 4As shown, the dimension of a single through hole 101 along the second direction is L3, and the number of through holes in each column of through holes 101 is N. Then L2 = L3 × N, where N is a positive integer. L2 / L1 represents the proportion of the total opening length of the opening area (i.e., the area where a column of through holes 101 is located) to the length of the membrane monomer 110 along the second direction. The membrane monomer 110 is in a tensile state during the process of covering the shell 210. Different values ​​of L2 / L1 result in different tensile deformations of the membrane monomer 110. The larger the value of L2 / L1, the greater the deformation of the membrane monomer 110 along the first direction when it is tensile. The dimension of the membrane monomer 110 along the first direction is equal to the center distance W between two adjacent rows of through holes on the membrane substrate 1. Due to the addition of through holes 101 on the membrane monomer 110, during the coating process, the membrane monomer 110 will elongate to a certain extent after being stretched under the influence of the belt tension. Thus, when the center distance between two adjacent rows of through holes on the membrane substrate 1 is not designed reasonably, the dimension of the membrane monomer 110 will also be unreasonable, which will affect the width and centering of the gap on the end side.

[0055] If W is less than C-W1-L2 / L1×4.5, then the value of W is too small, the distance between the first side 111 and the second side 112 after coating (i.e., the width of the gap along the X direction) is too large, the edge width W2 of the membrane unit 110 on the first side 211 is too small, the exposed part of the shell 210 is too large, the insulation performance of the outer surface of the cell 2 is poor, and the yield of the cell insulation withstand voltage test is significantly reduced. If W is greater than C-W1-L2 / L1×3.5, then W is too large, the width of the gap is too small, which makes the bonding area between the shell 210 and the adhesive too small, affecting the bonding strength between the shell 210 and the adhesive, and easily causing the risk of bonding failure between the cell 2 and the battery pack box.

[0056] Applying the insulating film structure of this embodiment, by opening a plurality of through holes 101 on the film substrate 1, and each film unit 110 cut from the film substrate 1 having a row of through holes 101, and after the film unit 110 covers the outer surface of the housing 210 of the battery cell 2, a gap is formed between the first side 111 and the second side 112 on the end side of the film unit 110, so that the parts of the housing 210 corresponding to the through holes 101 and the parts corresponding to the gaps on the end side can be exposed and bonded to the adhesive. Thus, while ensuring the bonding between the insulating film and the adhesive, a portion of the housing is directly bonded to the adhesive, increasing the bonding strength between the adhesive and the battery cell 2. Furthermore, by limiting the center distance W between two adjacent rows of through holes 101 on the film substrate 1 along the first direction and the preset distance W1 between the first side 111 and the second side 112 on the covered film unit 110, the film substrate... The dimension L1 of material 1 along the second direction and the sum of the opening dimensions L2 of multiple through holes 101 in each column along the second direction satisfy the relationship C-W1-L2 / L1×4.5≤W≤C-W1-L2 / L1×3.5. W is related to the ratio of the total opening length along the first direction on the membrane unit 110 to the length of the membrane unit 110, so that there is a reasonable spacing between two adjacent columns of through holes 101 on the membrane substrate 1, and thus the membrane unit 110 has a reasonable size along the first direction. After the membrane unit 110 is wrapped on the cell 2, it can ensure that the membrane unit 110 has sufficient coverage area on the shell 210, thereby ensuring the insulation and withstand voltage performance of the cell, and also ensure that there is sufficient spacing between the first side 111 and the second side 112, thereby ensuring the bonding strength between the cell 2 and the adhesive, and thus ensuring the structural strength and stability of the battery pack.

[0057] Optionally, W can take any value from C-W1-L2 / L1×3.5, C-W1-L2 / L1×3.8, C-W1-L2 / L1×4, C-W1-L2 / L1×4.2, C-W1-L2 / L1×4.5, or a value between any two values.

[0058] It should be noted that, Figure 1 The incoming material is an insulating film structure, which is unrolled from a whole roll of insulating film, which is about 100 meters long. Figures 2 to 3 The uncut portion of the insulating film structure. Figure 5 The membrane monomer 110 is formed after cutting, and one membrane monomer 110 is wrapped around the outer side of the housing 210 of a bare cell.

[0059] Previous cell 2 Figures 12 to 13 As shown, the membrane substrate 1 before improvement is as follows: Figure 14As shown, no through holes 101 are opened on the membrane substrate 1. The battery cell 2 is only bonded to the adhesive through the membrane monomer 110 covered on the outer surface of the housing 210. The housing 210 cannot be directly bonded to the adhesive, resulting in low bonding strength and insufficient bonding force. This can easily lead to the failure of the bonding between the membrane monomer 110 and the adhesive, which in turn causes the battery cell 2 to fall off from the housing.

[0060] In one embodiment, the sum of the opening dimensions L2 of the multiple through holes 101 in each column of through holes 101 along the second direction satisfies the relationship L1 of the membrane substrate 1 along the second direction: 0.5 ≤ L2 / L1 ≤ 0.8. It should be noted that the dimension of the membrane unit 110 along the second direction is equal to the dimension L1 of the membrane substrate 1 along the second direction. If L2 / L1 is less than 0.5, then along the second direction, the proportion of the total opening length of all through holes 101 on the membrane unit 110 is too small, resulting in insufficient opening area. Consequently, the area of ​​the housing 210 bonded to the adhesive through the through holes 101 is insufficient, leading to insufficient bonding strength and a risk of bonding failure between the cell 2 and the battery pack housing. If L2 / L1 is greater than 0.8, then along the second direction... In the first direction, the total length of all the through holes 101 on the membrane unit 110 is too large, the remaining solid part after the through holes 101 in the opening area is too small, and the deformation of the membrane unit 110 along the first direction is too large when it is tightened, which affects the width and centering of the gap on the end side, making the gap too small. The bonding area between the shell 210 and the adhesive through the gap is too small, which will also affect the bonding strength between the shell 210 and the adhesive, and easily lead to the risk of bonding failure between the cell 2 and the battery pack box.

[0061] Therefore, by limiting L2 / L1 to a value within the range of 0.5 to 0.8, the total opening length of all through holes 101 on the membrane unit 110 along the second direction has a reasonable proportion on the membrane unit 110. This ensures that the through holes 101 can provide sufficient contact area between the housing 210 and the adhesive, and also ensures that the gap on the end side can provide sufficient contact area between the housing 210 and the adhesive. This ensures the bonding strength between the two first sides 211 of the housing 210 and the adhesive, avoids the failure of the bonding between the cell 2 and the adhesive, and thus ensures the overall stability of the battery pack.

[0062] Optionally, the value of L2 / L1 is any one of 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8 or a value between any two values.

[0063] In one embodiment, the dimension L1 of the membrane substrate 1 along the second direction is in the range of 400mm ≤ L1 ≤ 600mm. If L1 is less than 400mm, the dimension of the membrane substrate 1 along the second direction is too small, that is, the dimension of the membrane monomer 110 along the second direction is too small, resulting in insufficient coverage on the housing 210 and difficulty in ensuring the insulation of the battery cell. If L1 is greater than 600mm, the dimension of the membrane substrate 1 along the second direction is too large, that is, the dimension of the membrane monomer 110 along the second direction is too large, exceeding the size of the housing 210, making subsequent cutting processes complex, reducing production efficiency, wasting materials, and increasing costs. Therefore, by limiting L1 to the range of 400mm to 600mm, it is possible to ensure that the membrane monomer 110 can better cover the outer surface of the housing 210, ensuring the insulation of the outer surface of the battery cell housing, thereby improving the safety of the battery cell 2, while also avoiding material waste, saving costs, and improving processing and production efficiency.

[0064] Optionally, the value of L1 is any one of 400mm, 420mm, 450mm, 480mm, 500mm, 530mm, 550mm, 570mm, and 600mm, or a value between any two of these values.

[0065] In one embodiment, further combination Figures 3 to 4 As shown, along the second direction, the distance between two adjacent through holes 101 is B, where the value of B is B≥8mm. It should be noted that B is the distance between two adjacent through holes 101 on the membrane unit 110 along the second direction, that is, the dimension of the solid portion between two adjacent through holes 101 along the second direction. If B is less than 8mm, the distance between two adjacent through holes 101 on the membrane unit 110 along the second direction is too small, and the self-strength of the solid portion between two adjacent through holes 101 is poor. During the wrapping process, under the influence of the tension of the insulating film, the elongation deformation of the insulating film after being stretched is too large. After wrapping, the width of the gap between the first side 111 and the second side 112 on the tail side is too small, which affects the bonding strength between the shell 210 and the adhesive, and is prone to the risk of bonding failure between the cell 2 and the battery pack box. In addition, the part of the membrane unit 110 located on both sides of the through hole 101 along the first direction may have inconsistent stretching length, which will affect the centering of the gap on the first side 211 and affect the accuracy of the film.

[0066] Therefore, by limiting B to be greater than or equal to 8mm, it can be ensured that there is a sufficient distance between two adjacent through holes 101 on the membrane unit 110 along the second direction, thereby avoiding excessive stretching deformation of the insulating film along the first direction during the film-making process, ensuring that the gap between the first side 111 and the second side 112 after film-making has a sufficient width, thereby ensuring that the housing 210 can be bonded to the adhesive through the gap and with sufficient bonding area, ensuring bonding strength, preventing the battery cell 2 from failing to bond with the housing and detaching, and ensuring the centering of the gap on the first side 211, thus improving the film accuracy.

[0067] Optionally, the value of B can be any one of 8mm, 8.2mm, 8.5mm, 9mm, 9.5mm, 10mm, 11mm, or a value between any two of these values, or a value greater than 11mm.

[0068] In one embodiment, further combination Figure 5 As shown, along the first direction, the distance from the center point of the through hole 101 to the first side 111 is equal to W / 2, and the distance from the center point of the through hole 101 to the second side 112 is also equal to W / 2. Here, the center point of the through hole 101 refers to the center point of any one of the through holes 101 on the membrane monomer 110. By limiting the distance from the center point of the through hole 101 to the first side 111 to be equal to the distance to the second side 112, and both being W / 2, the membrane monomer 110 is formed by cutting along the symmetrical line between two adjacent rows of through holes 101 on the membrane substrate 1. This facilitates processing control, simplifies the process, increases production efficiency, and ensures the symmetry of the membrane monomer 110. It also ensures that the edge distance from the first side 111 to the first side 211 on the finishing side is equal to the edge distance from the second side 112 to the first side 211, thereby ensuring the centering of the gap formed between the first side 111 and the second side 112 on the first side 211, guaranteeing film precision, and improving production yield.

[0069] It should be noted that when the center distance W between two adjacent rows of through holes 101 on the membrane substrate 1 along the first direction is not designed properly, the width W / 2 on both sides of the center line of the cut membrane unit 110 will be unreasonable, which will cause the width of the insulating film covered on the first side 211 of the tail side after wrapping to be either too large or too small, thereby affecting the adhesive coating area and the bonding strength between the cell and the battery pack box.

[0070] In one embodiment, a further combination Figure 2 As shown, the opening shape of the through-hole 101 is circular. The circular shape of the through-hole 101 makes the opening process easier to control, which is beneficial for improving production efficiency. Correspondingly, the cell 2 formed after the membrane monomer 110 is coated onto the housing 210 when the through-hole 101 is circular is as follows: Figure 10 As shown.

[0071] In other embodiments, the opening shape of the through hole 101 is polygonal. By setting the opening shape of the through hole 101 to be polygonal, it can also be ensured that the through hole 101 has sufficient opening area, thereby ensuring that the housing 210 can be bonded to the adhesive through the through hole 101. Preferably, further assembly Figure 3 As shown, the opening shape of the through hole 101 is rectangular. Correspondingly, the cell 2 formed after the membrane monomer 110 is coated onto the housing 210 is as follows: Figure 11 As shown. It can be understood that, as an alternative implementation, the opening shape of the through hole 101 can also be a triangle, a pentagon, or other polygons, or an oblong shape, an ellipse, or other shapes.

[0072] To verify the effectiveness, different Design of Experiment (DOE) tests were arranged to track the actual gap width (allowable dimensional tolerance ±1.0 mm) on the finished side after coating and the cell insulation withstand voltage test results. The test results of the examples and comparative examples are shown in Table 1. Several cells were used for testing in each comparative example and example, and the test results were statistically analyzed. The cell insulation withstand voltage test was conducted according to GB / T7752-1987. Specifically, the withstand voltage test was performed at 3500VDC for 2 seconds with a leakage current <2mA; and at 2350VAC for 2 seconds with a leakage current <2mA.

[0073] Table 1

[0074]

[0075] In this context, formula 1 represents C-W1-L2 / L1×4.5, formula 2 represents C-W1-L2 / L1×3.5, and whether W is within the specified range indicates whether C-W1-L2 / L1×4.5≤W≤C-W1-L2 / L1×3.5 is satisfied. It should be noted that W1 is the preset distance along the X direction between the first side 111 and the second side 112, which is the preset gap width on the wrapping end side. Since the insulating film is in a taut state during the film-making process, the film unit 110 is stretched and deformed along the first direction, and the actual length changes. Therefore, there will be a certain deviation between the actual gap width on the wrapping end side and the preset gap width. Within the allowable range of dimensional tolerance ±1.0mm, it is considered qualified. After the single cell has passed the withstand voltage test, if the leakage current is <2mA, the single cell insulation withstand voltage is considered qualified. The percentage of cells with qualified insulation withstand voltage in the same set of embodiments or comparative examples is the single cell insulation withstand voltage yield.

[0076] As can be seen from Table 1, in Examples 1 to 10, the value of W is within the range of C-W1-L2 / L1×4.5 to C-W1-L2 / L1×3.5 as defined in this application. The test results show that the insulation withstand voltage yield of a single cell is 99.977% or higher, that is, the insulation withstand voltage yield of the cell is high, and the actual gap width on the end side meets the dimensional tolerance (±1.0mm) requirement 100%, and all are qualified.

[0077] In Comparative Examples 1 and 2, the value of W is less than C-W1-L2 / L1×4.5, which is less than the lower limit of the range defined in this application and is not within the scope defined in this application. The single-cell insulation withstand voltage yield of Comparative Example 1 is 99.88% and the single-cell insulation withstand voltage yield of Comparative Example 2 is 99.35%, which is a significant decrease in yield. In addition, 23.3% of the cells in Comparative Example 1 have an actual gap width on the end side that exceeds the upper limit of 9.0 mm and 17.5% of the cells in Comparative Example 2 have an actual gap width on the end side that exceeds the upper limit of 9.8 mm, indicating that the proportion of unqualified cells is too high. In Comparative Example 3, the value of W is greater than C-W1-L2 / L1×3.5, which is greater than the lower limit of the range defined in this application and is not within the range defined in this application. Although the single cell insulation withstand voltage yield of Comparative Example 3 is 99.988%, the actual gap width on the end side of the cell is lower than the lower limit of 7.5mm in 21.7% of the cells, and the proportion of unqualified cells is too high.

[0078] It is evident that when W meets the design requirement of C-W1-L2 / L1×4.5≤W≤C-W1-L2 / L1×3.5 as defined in this application, there are no obvious abnormalities in the single-cell insulation withstand voltage test, and the actual gap width on the end side after coating meets the design tolerance. However, when the W value is less than the lower limit defined in this application, the gap on the end side after coating is too large, and the overlap distance on the first side 211 of the end side after coating is too small, resulting in a significant decrease in the yield of the cell insulation withstand voltage test. When the W value is greater than the upper limit defined in this application, although there are no obvious abnormalities in the yield of the insulation withstand voltage after coating, the gap width on the end side is lower than the lower limit of the design requirement, affecting the contact area between the shell 210 and the adhesive, that is, affecting the bonding area between the shell 210 and the battery pack box, thereby increasing the risk of bonding failure between the cell and the box.

[0079] According to an embodiment of the present invention, another aspect also provides a battery cell, such as... Figures 6 to 11As shown, the battery cell includes: a housing 210 and a membrane unit 110 cut from the aforementioned insulating film structure, with the membrane unit 110 covering the outer peripheral surface of the housing 210. By covering the outer peripheral surface of the housing 210 with the membrane unit 110, the insulation of the outer surface of the battery cell can be ensured, and the membrane unit 110 can have sufficient coverage area on the housing 210, thereby ensuring the insulation withstand voltage performance of the battery cell, while also ensuring the bonding strength between the battery cell 2 and the adhesive, increasing the stability of the battery cell 2 after bonding with the adhesive.

[0080] It should be noted that the battery cell has X, Y, and Z directions that intersect each other, and preferably, the X, Y, and Z directions are perpendicular to each other (e.g., ...). Figure 6 (As shown). The first side 211 of the housing 210 is parallel to the XY plane, and the second side 212 is parallel to the XZ plane.

[0081] In one embodiment, further combination Figure 6 and Figure 9 As shown, the housing 210 has two first side surfaces 211 arranged opposite to each other along the Z direction. The first side surface 111 and the second side surface 112 are located on the same first side surface 211. The width dimension of the first side surface 211 along the X direction is W0. The single-sided edge width of the membrane unit 110 on the first side surface 211 is W2. The preset distance W1 between the first side surface 111 and the second side surface 112 satisfies the following relationship with the width dimension W0 of the first side surface 211 along the X direction and the single-sided edge width W2 of the membrane unit 110 on the first side surface 211: W1=W0-2×W2, where W2≥1.5mm. It should be noted that both the first side 111 and the second side 112 overlap the first side 211. The edge width W2 of the membrane unit 110 on the first side 211 refers to the distance along the X direction between the side of the first side 211 that is closer to the first side 111 and the first side 111, or the distance between the side of the first side 211 that is closer to the second side 112 and the second side 112. W2 is the edge width on one side, and the total edge width of the membrane unit 110 on the first side 211 is 2×W2. If W2 is less than 1.5mm, the edge width on one side of the membrane unit 110 on the first side 211 is too small, the distance between the first side 111 and the second side 112 is too large, the area of ​​the first side 211 that is not covered by the insulating film is too large, and the insulation performance of the outer surface of the cell is too poor.

[0082] Therefore, by limiting the width W2 of the single-sided edge of the membrane monomer 110 on the first side 211 to be greater than or equal to 1.5 mm, it can be ensured that the insulating film has sufficient coverage area on the first side 211, thereby ensuring the insulation of the outer surface of the battery cell.

[0083] It should be noted that the first side 111 and the second side 112 are spaced apart, that is, they do not overlap. Therefore, W1 > 0, and W2 < W0 / 2 must be guaranteed.

[0084] In one embodiment, the length of the housing 210 along the Y direction is L0, and the value of L0 ranges from 400mm to 600mm. If L0 is less than 400mm, the housing 210 is too short, and the housing 210 cannot provide sufficient space for the electrode assembly, resulting in insufficient capacity of the battery cell 2. If L0 is greater than 600mm, the housing 210 is too long, making it difficult to process and shape. Therefore, by limiting L0 to a value between 400mm and 600mm, the housing 210 has a reasonable length, ensuring both sufficient capacity of the battery cell and smooth processing and shaping of the housing 210. Preferably, the dimension L1 of the membrane monomer 110 along the second direction is equal to the dimension L0 of the housing 210 along the Y direction.

[0085] Optionally, the value of L0 is any one of 400mm, 420mm, 450mm, 470mm, 500mm, 550mm, 600mm or a value between any two of these values.

[0086] In one embodiment, the total thickness of the housing 210 along the X direction is W0, and the value of W0 ranges from 15mm to 30mm. The total thickness of the housing 210 along the X direction is equal to the width of the first side 211 along the X direction, both being W0. If W0 is less than 15mm, the total thickness of the housing 210 along the X direction is too thin, resulting in insufficient space for the electrode assembly, insufficient capacity of the battery cell 2, difficulty in inserting the electrode assembly into the housing, and low battery cell production efficiency. If W0 is greater than 30mm, the total thickness of the housing 210 along the X direction is too thick, meaning the battery cell 2 is too thick, resulting in excessive heat generation and difficulty in heat dissipation during use, leading to poor thermal safety. Therefore, by limiting W0 to a value between 15mm and 30mm, it is possible to ensure that the battery cell has sufficient capacity, improve battery cell production efficiency, and avoid excessive heat generation during use, thus ensuring the thermal safety performance of the battery cell 2.

[0087] Optionally, the value of W0 is any one of 15mm, 18mm, 20mm, 23mm, 25mm, 27mm, 30mm or a value between any two of these values.

[0088] In one embodiment, the height of the housing 210 along the Z-direction is H0, and the value of H0 is in the range of 80mm ≤ H0 ≤ 130mm. If H0 is less than 80mm, the internal space of the housing 210 is insufficient, resulting in insufficient capacity of the battery cell 2; if H0 is greater than 130mm, the dimension of the housing 210 along the Z-direction is too large, the volume of the battery cell 2 is too large, and consequently, the dimension of the battery pack along the Z-direction is too large, occupying too much space and hindering installation. Therefore, by limiting H0 to a value between 80mm and 130mm, it is possible to ensure that the battery cell 2 has sufficient capacity while avoiding excessive space occupation by the battery cell 2 and the battery pack along the Z-direction, thereby facilitating the installation of the battery cell 2 and the battery pack.

[0089] Optionally, H0 can be any value among 80mm, 90mm, 100mm, 110mm, 120mm, and 130mm, or a value between any two of these values.

[0090] In one embodiment, the battery cell 2 further includes: a cover plate 201, the housing 210 having an open end, the cover plate 201 covering the open end of the housing 210; and an electrode assembly 202 disposed inside the housing 210, the electrode assembly 202 having electrode tabs, the cover plate 201 having electrode posts, and the electrode tabs being electrically connected to the electrode posts.

[0091] According to an embodiment of the present invention, another aspect provides a battery pack, comprising: a housing and the aforementioned battery cells, wherein the battery cells are disposed within the housing. The number of battery cells is plurality of cells. Optionally, the battery cells are lithium-ion cells.

[0092] In one embodiment, the battery pack further includes an adhesive. The adhesive is disposed at least at both ends of the battery cell along the Z-direction between the battery cell and the housing. The adhesive includes a main body and a filler portion. The main body is bonded to the outer surface of the membrane cell 110, and the filler portion fills the through hole 101 and the gap between the first side 111 and the second side 112. The filler portion is also partially bonded to the housing 210. By providing adhesive between the battery cell and the housing, the battery cell is bonded and fixed inside the housing. The adhesive is also bonded to the inner wall of the housing. At the same time, the main body of the adhesive is bonded to at least a portion of the outer surface of the membrane cell 110, and the filler portion is squeezed into the through hole 101 and the receiving space between the first side 111 and the second side 112. Thus, the portions of the housing 210 corresponding to the through hole 101 and the receiving space are directly bonded to the adhesive, improving the bonding strength between the adhesive and the battery cell 2, thereby further ensuring the relative stability of the battery cell 2 and the housing.

[0093] It should be noted that the housing includes a bottom shell and a top cover that interlock. One of the two first side surfaces 211 of the housing 210 faces the bottom surface of the bottom shell, and the other faces the top shell. The adhesive at both ends of the battery cell along the Z direction includes a main body and a filling part. The portion of one first side surface 211 exposed through the through hole 101 is bonded to the bottom surface of the bottom shell by the adhesive. The portion of the other first side surface 211 exposed through the gap between the first side edge 111 and the second side edge 112 is bonded to the inner wall of the top shell. The battery cell has two first surfaces arranged opposite each other along the Z direction and two second surfaces arranged opposite each other along the X direction. The first surfaces correspond to the first side surface 211 of the housing 210, and the second surfaces correspond to the second side surface 212 of the housing 210. In order to improve the bonding strength between the battery cell and the housing, the main body of the adhesive not only covers the first surface of the battery cell, but also a portion of the adhesive covers at least a portion of the area on the second surface of the battery cell that is connected to the first surface.

[0094] In one embodiment, the adhesive is a structural adhesive. Structural adhesives have advantages such as high bonding strength, strong load-bearing capacity, light weight, and good shock absorption and cushioning effects. They are widely used, technologically mature, and readily available. It is understood that, as an alternative implementation, other adhesives with certain bonding strength, such as epoxy resin adhesives, can also be used.

[0095] In this embodiment, the insulating film structure limits the center distance W (i.e., the window row spacing) between two adjacent rows of through holes 101 on the film substrate 1 along the first direction to satisfy: C-W1-L2 / L1×4.5≤W≤C-W1-L2 / L1×3.5. By reasonably designing the relationship between the center distance between two adjacent rows of through holes 101 on the film substrate 1 along the first direction and the dimensions of the film substrate 1 along the second direction, the total opening length of a row of through holes, etc., it can avoid the problem of poor insulation withstand voltage after the cell is wrapped due to unreasonable window row spacing design. It can also avoid the problem of large or small gap width on the end side after the cell is wrapped due to unreasonable gap spacing design, which would lead to large deviation of the edge distance from the edge of the gap to the edge of the first side 211. This avoids the problem of poor insulation withstand voltage after the cell is wrapped and avoids the problem of unstable gap width on the end side affecting the bonding area between the cell shell and the battery pack box, thereby ensuring the bonding strength between the cell and the box and ensuring the overall stability of the battery pack.

[0096] 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. An insulating film structure, characterized by, include: A membrane substrate having a plurality of rows of through holes spaced apart along a first direction, each row of through holes including a plurality of through holes spaced apart along a second direction, the center distance between two adjacent rows of through holes along the first direction being W, the dimension of the membrane substrate along the second direction being L1, and the sum of the opening dimensions of the plurality of through holes in each row along the second direction being L2. The membrane substrate is adapted to be cut into a plurality of membrane monomers arranged along a first direction. Each membrane monomer has a row of through holes. The membrane monomer forms a first side and a second side on both sides along the first direction. Each membrane monomer is adapted to cover the outer peripheral surface of a shell. The perimeter of the outer peripheral surface of the shell is C. After the membrane monomer is covered on the shell, the first side and the second side are spaced apart, and the preset distance between the first side and the second side is W1. The relationship between W and C, W1, L1, L2 is: C-W1-L2 / L1×4.5≤W≤C-W1-L2 / L1×3.

5.

2. The insulating film structure of claim 1, wherein The sum of the opening dimensions L2 of the plurality of through holes in each column along the second direction satisfies the following relationship with the dimension L1 of the membrane substrate along the second direction: 0.5≤L2 / L1≤0.

8.

3. The insulating film structure of claim 2, wherein The value range of the dimension L1 of the membrane substrate along the second direction is: 400mm≤L1≤600mm.

4. The insulating film structure of claim 1, wherein Along the second direction, the distance between two adjacent through holes is B, where the value of B is B≥8mm; And / or, along the first direction, the distance from the center point of the through hole to the first side is equal to W / 2, and the distance from the center point of the through hole to the second side is equal to W / 2.

5. The insulating film structure according to any one of claims 1 to 4, wherein The opening shape of the through hole is circular or polygonal.

6. An electric cell characterized by include: case; A membrane monomer cut from the insulating film structure of any one of claims 1 to 5, the membrane monomer covering the outer peripheral surface of the housing.

7. The electric cell of claim 6, wherein, The housing has two first side surfaces arranged opposite each other along the Z direction. The first side surface and the second side surface are located on the same first side surface. The width dimension of the first side surface along the X direction is W0. The single-sided edge width of the membrane monomer on the first side surface is W2. The preset distance W1 between the first side surface and the second side surface, the width dimension W0 of the first side surface along the X direction, and the single-sided edge width W2 of the membrane monomer on the first side surface satisfy the following relationship: W1=W0-2×W2, where W2≥1.5mm.

8. The electric cell of claim 6, wherein, The length of the shell along the Y direction is L0, and the value of L0 is in the range of 400mm≤L0≤600mm; And / or, the total thickness of the shell along the X direction is W0, and the value of W0 is in the range of 15mm≤W0≤30mm; And / or, the height of the housing along the Z direction is H0, and the value of H0 is in the range of 80mm≤H0≤130mm.

9. A battery pack, characterized by, include: Box; The battery cell according to any one of claims 6 to 8, wherein the battery cell is disposed within the housing.

10. The battery pack of claim 9, wherein, The battery pack also includes: An adhesive is provided at least at both ends of the battery cell along the Z direction between the battery cell and the housing. The adhesive includes a main body and a filling part. The main body is bonded to the outer surface of the membrane unit. The filling part fills the through holes and the gap between the first side and the second side, and the filling part is partially bonded to the housing.

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