Battery cell, battery, and battery module

Abstract

The present application relates to the technical field of batteries, and discloses a battery cell, a battery, and a battery module. The battery cell comprises: a plurality of electrode sheets; a separator stacked with the plurality of electrode sheets and adapted to separate the plurality of electrode sheets, wherein the separator at least partially covers the outer surface of the battery cell, and the separator forms a separator tail portion on the outer surface of the battery cell; and an insulating film having one end fixed on the outer side of the separator tail portion, wherein the insulating film at least partially covers the outer side of the separator that forms the outer surface of the battery cell. The puncture resistance of the separator is defined as f1, and the thickness of the separator is defined as d1; the puncture resistance of the insulating film is defined as f2, the thickness of the insulating film is defined as d2; it is satisfied that 0.1≤(f2·d1) / (f1·d2)≤9. In the battery cell provided by the present application, excessive hardness of the insulating film can be avoided, ensuring the wrapping capability of the insulating film for the separator and the battery cell; and the puncture-resistant strength of the insulating film can be ensured, preventing a puncture force from affecting the separator and causing damage thereto when the insulating film undergoes pressing, collision, or foreign object intrusion.

Description

Battery cells, batteries and battery modules

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411556206.2, filed on November 4, 2024, entitled "Battery Cell, Battery and Battery Module", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of battery cell technology, specifically to a battery cell, battery, and battery module. Background Technology

[0004] A battery cell is made by stacking or winding positive electrode plates, negative electrode plates, and a separator. The separator is placed between the positive and negative electrode plates to enable ion conduction and electronic insulation. Taking a wound battery cell as an example, the outermost layer of the battery cell is covered by a separator after winding. An insulating film is attached to the outside of the separator. If the puncture resistance of the insulating film is less than that of the separator, it cannot protect the separator from being punctured by external foreign objects.

[0005] However, if the puncture resistance of the insulating film is too high, it will be too thick and hard, which will result in poorer wrapping of the separator. Similarly, if the puncture resistance of the separator is too high, it will be too thick and hard, which will squeeze and interfere with the cell at the bending part, causing the cell to fall out. This can easily puncture the separator or insulating film. If the insulating film is broken, it will easily cause insulation failure. If the separator is broken, it will easily cause a short circuit between the positive and negative electrodes, resulting in safety problems. Summary of the Invention

[0006] In view of this, this application provides a battery cell, a battery, and a battery module to solve the problems that the insulation film of the battery cell is prone to insulation failure and the separator is prone to short circuit between the positive and negative electrodes.

[0007] In a first aspect, this application provides a battery cell, comprising:

[0008] Several electrode plates;

[0009] A separator is disposed between the positive and negative electrode plates; the separator at least partially covers the outer surface of the battery cell;

[0010] An insulating film, which at least partially covers the outside of the diaphragm;

[0011] Define the puncture resistance of the diaphragm as f1 and the thickness of the diaphragm as d1; define the puncture resistance of the insulating film as f2 and the thickness of the insulating film as d2, satisfying: 0.1≤(f2·d1) / (f1·d2)≤9.

[0012] Beneficial Effects: The battery cell provided in the embodiments of this application, by limiting the upper limit of the ratio of the puncture resistance of the insulating film to the puncture resistance of the separator, can avoid excessive hardness of the insulating film, ensuring the insulating film's ability to wrap the separator and the battery cell, and preventing the insulating film from losing elasticity after the battery expands during charging and discharging, thus preventing the insulating film from failing to conform to the expansion of the battery cell. Simultaneously, by limiting the lower limit of the ratio of the puncture resistance of the insulating film to the puncture resistance of the separator, the puncture resistance of the insulating film can be guaranteed. When subjected to compression, impact, or foreign object intrusion, it prevents the puncture force from affecting the separator and causing damage, thereby effectively preventing short circuits between the positive and negative electrodes due to separator rupture and improving safety performance.

[0013] Secondly, this application also provides a battery comprising: at least two cells as described above.

[0014] Since batteries include cells and have the same effect as cells, they will not be elaborated on here.

[0015] Thirdly, this application also provides a battery module, including: the battery as described above.

[0016] Since the battery module includes the battery cell and has the same effect as the battery cell, it will not be elaborated here. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or 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 application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 is a cross-sectional schematic diagram of the battery cell of the first form of this application in the direction perpendicular to the height;

[0019] Figure 2 is a schematic cross-sectional view of the battery cell of the second type in this application in the direction perpendicular to the height.

[0020] Figure 3 is a schematic cross-sectional view of the battery cell covered with an insulating film in the present application, perpendicular to the height direction.

[0021] Figure 4 is a schematic cross-sectional view of the battery cell covered with an insulating film in this application, perpendicular to the height direction.

[0022] Figure 5 is a schematic diagram of the battery of this application;

[0023] Figure 6 is a schematic diagram of the battery cell covered with an insulating film according to this application in the direction perpendicular to the thickness.

[0024] Explanation of reference numerals in the attached drawings: 1. Electrode; 11. Positive electrode; 12. Negative electrode; 2. Shell; 3. Separator; 4. Insulating film; 5. Separator end; 100. Cell; 101. Straight section; 1011. First region; 1012. Second region; 102. Side section. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.

[0029] A battery cell is formed by stacking or winding positive electrode plates, negative electrode plates, and a separator. The separator is placed between the positive and negative electrode plates to achieve ion conduction and electronic insulation. Taking a wound battery cell as an example, the outermost layer of the wound cell is covered with a separator, and insulating tape is attached to the outside of the separator. When the battery is squeezed, impacted, or invaded by foreign objects, the insulating film and / or separator can easily be punctured. A ruptured insulating film can easily lead to insulation failure, while a ruptured separator can easily cause a short circuit between the positive and negative electrodes, resulting in safety issues. Therefore, it is essential to ensure that the insulating film and separator have appropriate puncture resistance. This reduces the likelihood of the insulating film and / or separator being easily punctured when the battery is squeezed, impacted, or invaded by foreign objects, thereby avoiding insulation failure due to insulating film rupture and short circuits between the positive and negative electrodes caused by separator rupture, and improving the safety performance of the battery cell.

[0030] The embodiments of this application are described below with reference to Figures 1 to 6.

[0031] According to an embodiment of this application, in one aspect, a battery cell 100 is provided, comprising:

[0032] Several electrode plates 1;

[0033] A separator 3 is disposed between the positive and negative electrode plates; the separator 3 at least partially covers the outer surface of the battery cell;

[0034] Insulating film 4, which at least partially covers the outside of diaphragm 3;

[0035] Define the puncture resistance of diaphragm 3 as f1 and the thickness of diaphragm 3 as d1; define the puncture resistance of insulating film 4 as f2 and the thickness of insulating film 4 as d2, satisfying: 0.1≤(f2·d1) / (f1·d2)≤9.

[0036] It should be noted that the battery cell 100 includes several electrode sheets 1, specifically referring to the battery cell 100 including at least two layers of electrode sheets 1.

[0037] In this embodiment, the battery cell 100 is formed by stacking or winding a positive electrode 11, a negative electrode 12, and a separator 3. The battery cell 100 can be a wound battery cell or a stacked battery cell. A wound battery cell includes a positive electrode 11 and a negative electrode 12, with a separator 3 between the positive and negative electrode 11 and 12. The cells are continuously wound to form the smallest charging and discharging unit. A stacked battery cell includes a positive electrode 11 and a negative electrode 12, with a separator 3 between the positive and negative electrode 11 and 12. The cells are stacked to form a continuous stack, which is then cut into multiple stacked units, and these stacked units are stacked to form a stacked battery cell.

[0038] As one implementation, as shown in Figure 1, the battery cell is composed of a positive electrode 11, a negative electrode 12, and a separator 3 stacked sequentially, with the positive electrode 11 and the negative electrode 12 arranged alternately. That is, the electrodes adjacent to both sides of the positive electrode 11 along the stacking direction are both negative electrodes 12, and the electrodes adjacent to both sides of the negative electrode 12 along the stacking direction are both positive electrodes 11. A separator 3 is provided between every two adjacent electrodes 1. The separator 3 can be a continuous film structure or a discontinuous layered film structure.

[0039] As another implementation, as shown in Figure 2, the battery cell is formed by winding a positive electrode 11, a negative electrode 12, and a separator 3. Using one of the positive electrode 11 or the negative electrode 12 as the winding center, the separator 3 is continuously wound. After winding, the positive electrode 11 and the negative electrode 12 are arranged in an alternating pattern; that is, the electrodes adjacent to both sides of the positive electrode 11 along the stacking direction are both negative electrodes 12, and the electrodes adjacent to both sides of the negative electrode 12 along the stacking direction are both positive electrodes 11. A separator 3 is provided between every two adjacent electrodes 1.

[0040] After the predetermined number of positive electrode plates 11 and negative electrode plates 12 are stacked, the shape of the battery cell 100 is basically formed. At this time, the separator 3 continues to be wound around the battery cell 100 more than once, so that the separator 3 can at least partially cover the outer surface of the battery cell, thereby preventing the positive electrode plate 11 or the negative electrode plate 12 from being directly exposed on the outermost layer of the battery cell 100, so that the separator 3 plays an insulating and protective role.

[0041] Since puncture strength = puncture force / thickness, in this embodiment, (f2·d1) / (f1·d2) is specifically interpreted as f2 / d2÷f1 / d1, which is the ratio of the puncture resistance of the insulating film 4 to the puncture resistance of the diaphragm 3.

[0042] In this embodiment, both the insulating film 4 and the separator 3 need to have sufficient puncture resistance to ensure that the battery cell 100 is not affected by external impurities or particulate matter. Optionally, this can be achieved by limiting the range of (f2·d1) / (f1·d2), that is, the ratio range of the puncture resistance of the insulating film 4 to that of the separator 3. If the ratio is too large, the puncture resistance of the insulating film 4 will be too high, reducing its ability to wrap the separator 3 and the battery cell 100. Simultaneously, the elasticity of the insulating film 4 will decrease after the battery expands during charging and discharging, making it unable to conform properly to the expansion of the battery cell, easily resulting in insufficient constraint on the battery cell 100. Conversely, if the ratio is too small, the puncture resistance of the insulating film 4 will be weak. When subjected to compression, impact, or foreign object intrusion, the puncture force will affect the separator 3, causing damage to the separator 3, which may lead to separator rupture and short circuit between the positive and negative electrodes, resulting in safety issues.

[0043] The battery cell 100 provided in the embodiments of this application, by limiting the upper limit of the ratio range of the puncture resistance strength of the insulating film 4 to the puncture resistance strength of the separator 3, can avoid the puncture resistance strength of the insulating film 4 being too high, ensuring the ability of the insulating film 4 to wrap the separator 3 and the battery cell 100, and preventing the elasticity of the insulating film 4 from deteriorating after the battery expands during charging and discharging, thus preventing the insulating film 4 from failing to wrap the battery cell properly according to its expansion. At the same time, by limiting the lower limit of the ratio range of the puncture resistance strength of the insulating film 4 to the puncture resistance strength of the separator 3, the puncture resistance strength of the insulating film 4 can be guaranteed, preventing the puncture force from affecting the separator 3 and causing damage to the separator 3 when subjected to compression, collision, or foreign object intrusion, thereby effectively preventing the occurrence of positive and negative short circuits caused by separator rupture and improving safety performance.

[0044] For example, in this application, the value of (f2·d1) / (f1·d2) can be 0.1 or 0.5 or 1 or 1.2 or 1.5 or 1.8 or 2.0 or 2.5 or 2.8 or 3.0 or 3.4 or 4 or 4.2 or 5.1 or 6 or 7.4 or 8 or 8.5 or 9, or it can be any of the above two values ​​forming an interval range.

[0045] In some embodiments, the puncture resistance f1 of the diaphragm 3 satisfies: 200gf≤f1≤800gf.

[0046] As optional parameter values, the puncture resistance f1 of the diaphragm 3 can be: 200gf, 300gf, 380gf, 420gf, 510gf, 580gf, 630gf, 743gf, or 800gf, etc.

[0047] In an optional embodiment, the puncture resistance f1 of the diaphragm 3 satisfies: 250gf≤f1≤750gf.

[0048] As optional parameter values, the puncture resistance f1 of the diaphragm 3 can be: 250gf, 300gf, 380gf, 420gf, 510gf, 580gf, 630gf, 743gf, or 750gf, etc.

[0049] In some embodiments, the thickness d1 of the diaphragm 3 satisfies: 4 micrometers ≤ d1 ≤ 25 micrometers.

[0050] As an optional parameter value, the thickness d1 of the diaphragm 3 can be: 4 micrometers, 5 micrometers, 6 micrometers, 7 micrometers, 9 micrometers, 11 micrometers, 12 micrometers, 15 micrometers, 17 micrometers, 19 micrometers, 20 micrometers, 21 micrometers, 23 micrometers, or 25 micrometers, etc.

[0051] In an optional embodiment, the thickness d1 of the diaphragm 3 satisfies: 5 micrometers ≤ d1 ≤ 20 micrometers.

[0052] As an optional parameter value, the thickness d1 of the diaphragm 3 can be: 5 micrometers, 6 micrometers, 7 micrometers, 9 micrometers, 11 micrometers, 12 micrometers, 15 micrometers, 17 micrometers, 19 micrometers, or 20 micrometers, etc.

[0053] In some embodiments, the puncture resistance f2 of the insulating film 4 satisfies: 700gf≤f2≤2050gf.

[0054] As optional parameter values, the puncture resistance f2 of the insulating film 4 can be: 700gf, 900gf, 1000gf, 1200gf, 1500gf, 1700gf, 1900gf, 2000gf, or 2050gf, etc.

[0055] In an optional embodiment, the puncture resistance f2 of the insulating film 4 satisfies: 800gf≤f2≤2040gf.

[0056] As optional parameter values, the puncture resistance f2 of the insulating film 4 can be: 800gf, 900gf, 1000gf, 1200gf, 1500gf, 1700gf, 1900gf, 2000gf, or 2040gf, etc.

[0057] In some embodiments, the thickness d2 of the insulating film 4 satisfies: 20 micrometers ≤ d2 ≤ 150 micrometers.

[0058] As an optional parameter value, the thickness d2 of the insulating film 4 can be: 20 micrometers, 23 micrometers, 24 micrometers, 35 micrometers, 46 micrometers, 57 micrometers, 79 micrometers, 92 micrometers, 110 micrometers, 125 micrometers, or 150 micrometers, etc.

[0059] In an optional embodiment, the thickness d2 of the insulating film 4 satisfies: 25 micrometers ≤ d2 ≤ 100 micrometers.

[0060] As an optional parameter value, the thickness d2 of the insulating film 4 can be: 25 micrometers, 27 micrometers, 29 micrometers, 35 micrometers, 46 micrometers, 57 micrometers, 79 micrometers, 92 micrometers, 98 micrometers, or 100 micrometers, etc.

[0061] In an optional embodiment, the range of values ​​for (f2·d1) / (f1·d2) satisfies: 1≤(f2·d1) / (f1·d2)≤7.

[0062] For example, in this application, the value of (f2·d1) / (f1·d2) can be 1 or 1.2 or 1.5 or 1.8 or 2.0 or 2.5 or 2.8 or 3.0 or 3.4 or 4 or 4.2 or 5 or 5.1 or 6 or 7, or it can be any range formed by any two of the above values.

[0063] In some embodiments, the electrode 1 includes a positive electrode 11, a negative electrode 12 and a separator 3. The separator 3 is located between the positive electrode 11 and the negative electrode 12, and along the height direction of the cell, the height of the positive electrode 11 is less than the height of the negative electrode 12, and the height of the negative electrode 12 is less than the height of the separator 3.

[0064] The separator 3 is located between the positive electrode 11 and the negative electrode 12. At this time, the cell 100 can be formed by winding or by stacking.

[0065] During charging, Li+ ions are extracted from the positive electrode and inserted into the negative electrode. If the space in the negative electrode is insufficient, the resistance to Li+ insertion into the negative electrode will increase. This causes Li+ ions that cannot be inserted into the negative electrode to gain electrons on the surface of the negative electrode, resulting in lithium plating. Ultimately, this leads to a decrease in the performance of the lithium battery and a significant reduction in cycle life.

[0066] In this embodiment, by making the height of the positive electrode 11 less than the height of the negative electrode 12 along the cell height direction, lithium plating can be reduced, thereby ensuring battery performance and preventing a significant reduction in cycle life. Furthermore, by making the height of the negative electrode 12 less than the height of the separator 3, the separator 3 ensures its insulating function, preventing short circuits caused by overlap between the positive and negative electrodes.

[0067] In some embodiments, at least one edge of the insulating film 4 extends beyond the positive electrode 11 along the cell height direction.

[0068] By ensuring that at least one edge of the insulating film 4 extends beyond the positive electrode 11, it is possible to prevent the edge of the insulating film 4 from squeezing the positive electrode 11 during battery expansion, thus avoiding the situation where the positive electrode 11 falls off.

[0069] The insulating film 4 is higher than the positive electrode 11 along the cell height direction, and can completely cover the positive electrode 11 along the cell height direction. When the insulating film 4 is only attached to the negative electrode 12, the insulating film 4 will squeeze the negative electrode 12 after the cell 100 expands, causing the negative electrode 12 to fall off, affecting the battery cycle performance, and there is also a risk that the falling material will puncture the separator 3. In this embodiment, at least one edge of the insulating film 4 extends beyond the positive electrode 11 along the cell height direction, which can avoid the situation where the insulating film 4 squeezes the negative electrode 12 and causes the negative electrode 12 to fall off after the cell 100 expands. In addition, since the height of the positive electrode 11 is less than the height of the negative electrode 12, that is, there is a missing electrode in the area above the positive electrode 11 and below the negative electrode 12 along the cell height direction, the edge of the insulating film 4 can be attached to this position to fill the missing position of the negative electrode without occupying space. In addition, the edge of the insulating film 4 attached to this position can provide a certain support for the positive electrode 11 and the separator 3, so that the insulating film 4 can also be better attached.

[0070] As an optional implementation, the two edges of the insulating film 4 extend beyond the positive electrode plate 11 along the height direction of the cell.

[0071] In some embodiments, along the cell height direction, at least one edge of the insulating film 4 is located between the positive electrode 11 and the negative electrode 12.

[0072] At least one edge of the insulating film 4 is located between the positive electrode 11 and the negative electrode 12, thereby preventing the edge of the insulating film 4 from squeezing the positive electrode 11 when the battery expands, and preventing the positive electrode 11 from falling off.

[0073] As an optional implementation, along the height direction of the cell, both sides of the insulating film 4 are located between the positive electrode 11 and the negative electrode 12.

[0074] In some other embodiments, at least one edge of the insulating film 4 extends beyond the negative electrode 12 along the cell height direction.

[0075] Along the height direction of the cell, since the height of the positive electrode 11 is less than the height of the negative electrode 12, at least one edge of the insulating film 4 extends beyond the negative electrode 12. That is, the insulating film 4 completely covers the positive and negative electrodes, which can better protect the positive and negative electrodes. At the same time, it also prevents the edge of the insulating film 4 from squeezing the negative electrode 12 when the battery expands, thus preventing the negative electrode 12 from falling off.

[0076] As an optional implementation, the two edges of the insulating film 4 extend beyond the negative electrode plate 12 along the height direction of the cell.

[0077] The height of the insulating film 4 along the height direction of the battery cell is greater than the height of the positive electrode 11 and the negative electrode 12. The insulating film 4 can completely cover the positive electrode 11 and the negative electrode 12 along the height direction of the battery cell, avoiding the situation of positive and negative short circuit caused by being punctured by the separator 3, thus improving safety.

[0078] In some embodiments, along the cell height direction, at least one edge of the insulating film 4 is located between the negative electrode 12 and the separator 3.

[0079] When the insulating film 4 extends beyond the edge of the separator 3, due to the lack of shielding from the battery cell, if the edge is glued during assembly, it may stick to other battery components or foreign objects, thus interfering with smooth assembly and posing certain safety hazards. By placing at least one edge of the insulating film 4 between the negative electrode 12 and the separator 3, the situation where the insulating film 4 extends beyond the separator 3 and sticks to external foreign objects during assembly can be avoided.

[0080] As an optional implementation, along the height direction of the cell, both sides of the insulating film 4 are located between the negative electrode plate 12 and the separator 3.

[0081] In some other embodiments, at least one edge of the insulating film 4 extends beyond the separator 3 along the cell height direction.

[0082] By extending at least one edge of the insulating film 4 beyond the separator 3, the entire surface of the cell can be protected, preventing damage to the positive and negative electrodes or short circuits caused by damage to the separator 3.

[0083] As an optional implementation, the two edges of the insulating film 4 extend beyond the separator 3 along the height direction of the battery cell.

[0084] In some embodiments, along the height direction of the cell, both sides of the insulating film 4 extend beyond the positive electrode 11.

[0085] By ensuring that both sides of the insulating film 4 extend beyond the positive electrode 11, it is possible to protect both ends of the positive electrode 11 along the height direction of the cell. The insulating film 4 will not press against the positive electrode 11 due to battery expansion, thus preventing the positive electrode 11 from falling off and thus avoiding affecting the positive and negative electrode paths.

[0086] In some embodiments, the insulating film 4 has at least a partial adhesive layer on both sides of its edges along the height direction of the battery cell.

[0087] To prevent foreign objects from sticking to the insulating film 4 after it extends beyond the separator 3 during assembly, this embodiment ensures that at least part of the two edges of the insulating film 4 along the height direction of the battery cell are free of adhesive layer, thereby ensuring smooth assembly and reducing safety hazards.

[0088] The height of the insulating film 4 along the cell height direction is greater than the height of the separator 3. When the insulating film 4 extends beyond the edge, due to the lack of cell shielding, if the edge is covered with adhesive during assembly, it may stick to other battery components or foreign objects, thus interfering with smooth assembly and posing certain safety hazards. In this embodiment, the upper and lower edges of the insulating film 4 along the cell height direction are at least partially free of adhesive layers, ensuring smooth assembly and reducing safety hazards.

[0089] In some embodiments, the puncture resistance f2 of the insulating film 4 is in the range of 700gf≤f2≤2050gf.

[0090] If the puncture resistance of the insulating film 4 is too high, it will become too rigid and unable to properly wrap the battery cell. It will also cause lithium plating at corners where stress is high. Conversely, if the puncture resistance of the insulating film 4 is too low, foreign objects can easily puncture it, potentially damaging the separator 3 and causing a short circuit, posing a safety hazard.

[0091] This embodiment limits the upper and lower limits of the puncture resistance f2 of the insulating film 4, which enables the insulating film 4 to better fit and wrap the battery cell, avoiding the compression of the battery cell at corner stress points to prevent lithium plating; at the same time, it can reduce the occurrence of foreign objects easily puncturing the insulating film 4 and thus easily damaging the separator 3.

[0092] As optional parameter values, the puncture resistance f2 of the insulating film 4 can be: 700gf, 900gf, 1000gf, 1200gf, 1500gf, 1700gf, 1900gf, 2000gf, or 2050gf, etc.

[0093] In some embodiments, the battery cell has a straight section 101 and a side section 102, and the separator 3 forms a separator tail portion 5 in the straight section 101;

[0094] Along the winding direction of the separator 3, the area on the surface of the battery cell located in the straight section 101 and overlapping with the end portion 5 of the separator is defined as the first region 1011, and the area on the surface of the battery cell located in the straight section 101 and outside the end portion 5 of the separator is defined as the second region 1012.

[0095] The insulating film 4 is at least partially attached to the first region 1011.

[0096] In this embodiment, by attaching the insulating film 4 to the first region 1011 on the outer surface of the battery cell, the thickness of the protective layer on the outer surface of the battery cell can be further increased, the puncture resistance of the battery cell can be enhanced, and the internal battery cell can be protected from foreign objects.

[0097] In this embodiment, the battery cell 100 is defined as having a straight section 101. For a stacked battery, the area between the two ends along the length of the battery cell is the straight section 101; while for a wound battery, the straight section 101 is the area excluding the outer arc-shaped R-angle. The area with the arc-shaped R-angle is the side section 102. In this embodiment, side sections 102 are provided on both sides of the straight section 101 along the length direction of the battery cell, and straight sections 101 are formed on both sides along the thickness direction of the battery cell.

[0098] Since the separator 3 typically lacks adhesive properties, the separator end 5 cannot be completely bonded and fixed to the battery cell 100. By further wrapping an insulating film 4 around the outside of the separator 3, fixing one end of the insulating film 4 to the outside of the separator end 5, and continuing to wrap the insulating film 4 around the outer surface of the battery cell, the insulating film 4 at least partially covers the outside of the separator 3 that forms the outer surface of the battery cell. This not only achieves the fixation of the separator end 5 of the separator 3, but also further improves the insulation performance of the outermost layer of the battery cell 100, thus protecting the separator 3 and the electrodes inside the battery cell 100.

[0099] In some embodiments, the insulating film 4 is at least partially attached to the first region 1011, satisfying: 0.1≤(f2·d1) / (f1·d2)≤7.

[0100] The separator 3 forms a separator tail 5 in the straight section 101 of the cell. The separator tail 5 is located in the first region 1011 of the cell. The separator tail 5 can serve as a protective barrier outside the cell. At this time, the protective barrier of the first region 1011 has one more layer than that of the second region 1012. There are more external protective barriers for the positive and negative electrodes. Therefore, the puncture resistance of the insulating film 4 attached to the first region 1011 can be appropriately reduced. At this time, the value range of (f2·d1) / (f1·d2) is lower than the upper limit.

[0101] For example, in this application, the value of (f2·d1) / (f1·d2) can be 0.1 or 0.5 or 1 or 1.2 or 1.5 or 1.8 or 2.0 or 2.5 or 2.8 or 3.0 or 3.4 or 4 or 4.2 or 5 or 5.5 or 6.1 or 7, or it can be any of the above two values ​​forming an interval range.

[0102] In some embodiments, the insulating film 4 extends to the second region 1012, satisfying: 1≤(f2·d1) / (f1·d2)≤9.

[0103] At the winding end of the separator 3, a separator tail portion 5 is formed in the straight section 101 of the cell. Located in the first region 1011 of the cell, the separator tail portion 5 can serve as a protective barrier outside the cell, while located in the second region 1012 of the cell, it lacks a separator 3 as a protective barrier. At this time, the second region 1012 provides less external protection for the positive and negative electrodes, so it is necessary to strengthen the puncture resistance of the separator 3 to ensure that the internal cell is not affected by foreign objects. In this case, the value range of (f2·d1) / (f1·d2) is higher than the lower limit.

[0104] For example, in this application, the value of (f2·d1) / (f1·d2) can be 1 or 1.2 or 1.5 or 1.8 or 2.0 or 2.5 or 2.8 or 3.0 or 3.4 or 4 or 4.2 or 5 or 5.1 or 5.5 or 6 or 7.4 or 8 or 8.5 or 9, or it can be any of the above two values ​​forming an interval range.

[0105] In some embodiments, the insulating film 4 is at least partially attached to the first region 1011, at least one end of the insulating film 4 extends circumferentially along the cell, and the edge of the insulating film 4 along the circumferential direction of the cell does not extend beyond the straight section 101.

[0106] In this embodiment, the following condition is met: 800gf≤f2≤2050gf.

[0107] Since the battery surface is more prone to expansion, and foreign objects are more likely to puncture the protective barrier outside the battery cell after expansion, this embodiment extends the insulating film 4 at least one end along the circumference of the battery cell, and the edge of the insulating film 4 along the circumference of the battery cell does not exceed the straight section 101, thereby increasing the protective barrier on the battery surface.

[0108] Furthermore, the insulating film 4 has greater puncture resistance, thereby enhancing the protection of the battery surface.

[0109] In other embodiments, the insulating film 4 is at least partially attached to the first region 1011, at least one end of the insulating film 4 extends circumferentially along the cell, and the edge of the insulating film 4 extends beyond the straight section 101 along the circumferential direction of the cell.

[0110] In this embodiment, the following condition is satisfied: 700gf≤f2≤2040gf.

[0111] The insulating film 4 extends beyond the straight section 101 along the circumferential edge of the battery cell, that is, the insulating film 4 extends to the side section 102 along the circumferential direction of the battery cell. The side section 102 is the area of ​​the arc-shaped R-angle of the battery cell. The stress in this area is relatively large, so the insulating film 4 is difficult to attach and cover, and it is easy to peel off. If the puncture resistance of the insulating film 4 is too high, the insulating film is too hard, which is not conducive to the covering of the insulating film 4 in the side section 102. Therefore, when the insulating film 4 extends beyond the straight section 101 along the circumferential edge of the battery cell, it is necessary to reduce the upper limit of the range of the puncture resistance of the insulating film 4.

[0112] In some embodiments, the insulating film 4 is at least partially attached to the first region 1011, at least one end of the insulating film 4 extends circumferentially along the cell, and the edge of the insulating film 4 along the circumferential direction of the cell extends beyond the straight section 101, with the edge of at least one end of the insulating film 4 located between the side section 102 at half its thickness and the straight section 101.

[0113] When the edge of the insulating film 4 is within half the thickness of the side segment 102, less insulating film 4 is attached to the side segment 102, making it easier for the edge to curl up. Therefore, the puncture resistance of the insulating film 4 should be appropriately reduced.

[0114] In some other embodiments, the insulating film 4 is attached to a first region 1011 of the first side straight section 101, at least one end of the insulating film 4 extends toward the second side straight section 101 along the circumference of the battery cell, and the edge of the insulating film 4 along the circumference of the battery cell extends beyond the straight section 101, and the edge of at least one end of the insulating film 4 extends beyond 1 / 2 of the thickness of the side section 102.

[0115] At least one edge of the insulating film 4 extends beyond half the thickness of the side segment 102, at which point the insulating film 4 covers most of the side segment 102 and protects the side segment 102.

[0116] In some other embodiments, the insulating film 4 is attached to a first region 1011 of the first side straight section 101, at least one end of the insulating film 4 extends toward the second side straight section 101 along the circumferential direction of the battery cell, and the edge of the insulating film 4 along the circumferential direction of the battery cell extends beyond the straight section 101, with the edge of at least one end of the insulating film 4 located between the side section 102 at half the thickness and the second side straight section 101.

[0117] At least one edge of the insulating film 4 is located between half the thickness of the side segment 102 and the second straight side segment 101. At this time, the insulating film 4 covers most of the side segment 102 and protects the side segment 102.

[0118] In some other embodiments, the insulating film 4 is attached to a first region 1011 of the first side straight section 101, at least one end of the insulating film 4 extends circumferentially toward the second side straight section 101 along the cell, and the edge of at least one end of the insulating film 4 extends beyond the side section 102.

[0119] The insulating film 4 has at least one edge extending beyond the side section 102, at which point the insulating film 4 completely covers the side section 102, providing good protection for the side section 102.

[0120] In some other embodiments, the insulating film 4 is attached to a first region 1011 of the first side straight section 101, at least one end of the insulating film 4 extends circumferentially toward the second side straight section 101 along the cell, and the edge of at least one end of the insulating film 4 is located in the second side straight section 101.

[0121] In this embodiment, the edge of the first end of the insulating film 4 is attached to the first region 1011 of the first side straight section 101, the insulating film 4 covers the second region 1012 of the first side straight section 101 and covers the first side section, and the edge of the second end of the insulating film 4 is located in the second side straight section 101.

[0122] At this time, the insulating film 4 also protects the second straight section 101 of the battery cell. It can effectively protect both the contact surface between the battery cell and the casing, and the contact surface between the battery cell and another battery cell, preventing foreign objects from puncturing it.

[0123] In some other embodiments, the side segment 102 adjacent to the first region 1011 is defined as the first side segment, and the side segment 102 adjacent to the second region 1012 is defined as the second side segment.

[0124] The insulating film 4 is attached to the first region 1011 of the first side straight section 101. At least one end of the insulating film 4 extends along the circumference of the battery cell. The insulating film 4 covers the first side section and the second side straight section 101. The edge of at least one end of the insulating film 4 extends beyond the second side straight section 101.

[0125] In this embodiment, the edge of the first end of the insulating film 4 is attached to the first region 1011 of the first side straight section 101. The insulating film 4 covers the second region 1012 of the first side straight section 101, covers the first side section, and covers the second side straight section 101, so that the edge of the second end of the insulating film 4 is located beyond the second side straight section 101.

[0126] At this time, the insulating film 4 fully covers the second straight section 101 of the battery cell, which can better ensure that foreign objects will not puncture the diaphragm.

[0127] In some other embodiments, the edge of at least one end of the insulating film 4 is located between the second side straight section 101 and half the thickness of the second side edge section.

[0128] In this embodiment, the edge of the first end of the insulating film 4 is attached to the first region 1011 of the first side straight section 101. The insulating film 4 covers the second region 1012 of the first side straight section 101, covers the first side segment, covers the second side straight section 101, and at least partially covers the second side segment; such that the edge of the second end of the insulating film 4 is located between the thickness of the second side straight section 101 and the second side segment at 1 / 2 of the thickness.

[0129] At this point, the insulating film 4 fully covers the second straight section 101 of the battery cell, which better ensures that foreign objects will not puncture the diaphragm. It also provides some protection for the second side section, protecting it from the influence of foreign objects.

[0130] In other embodiments, the edge of at least one end of the insulating film 4 extends beyond half the thickness of the second side segment.

[0131] In this embodiment, the edge of the first end of the insulating film 4 is attached to the first region 1011 of the first side straight section 101. The insulating film 4 covers the second region 1012 of the first side straight section 101, covers the first side section, covers the second side straight section 101, and at least partially covers the second side section; such that the edge of the second end of the insulating film 4 exceeds 1 / 2 of the thickness of the second side section.

[0132] At this point, the insulating film 4 fully covers the second straight section 101 of the battery cell, which better ensures that foreign objects will not puncture the diaphragm. Furthermore, it provides more coverage to the second side section, protecting it from foreign objects and further increasing its resistance to foreign objects.

[0133] In some other embodiments, the edge of at least one end of the insulating film 4 is located between the thickness of the second side segment and the first side straight segment 101 at half the thickness of the second side segment.

[0134] In this embodiment, the edge of the first end of the insulating film 4 is attached to the first region 1011 of the first side straight section 101. The insulating film 4 covers the second region 1012 of the first side straight section 101, covers the first side section, covers the second side straight section 101, and at least partially covers the second side section; such that the edge of the second end of the insulating film 4 is located between the first side straight section 101 and the second side straight section at 1 / 2 of the thickness of the second side section.

[0135] At this point, the insulating film 4 fully covers the second straight section 101 of the battery cell, which better ensures that foreign objects will not puncture the diaphragm. Furthermore, it provides more coverage to the second side section, protecting it from foreign objects and further increasing its resistance to foreign objects.

[0136] In some other embodiments, the side segment 102 adjacent to the first region 1011 is defined as the first side segment, and the side segment 102 adjacent to the second region 1012 is defined as the second side segment.

[0137] The insulating film 4 is attached to the first region 1011 of the first side straight section 101. At least one end of the insulating film 4 extends along the circumference of the battery cell. The insulating film 4 covers the first side section and the second side straight section 101. The edge of at least one end of the insulating film 4 extends beyond the second side section.

[0138] In this embodiment, the edge of the first end of the insulating film 4 is attached to the first region 1011 of the first side straight section 101. The insulating film 4 covers the second region 1012 of the first side straight section 101, and covers the first side section, and covers the second side straight section 101, so that the insulating film 4 wraps around the first side straight section 101 again, thereby enveloping most or the entire battery cell, and enhancing the battery cell's ability to resist foreign objects.

[0139] In some other embodiments, the insulating film 4 has both ends of its circumferential edge located in the straight section 101.

[0140] Since the large surface of the battery is where the expansion is most severe, foreign objects are more likely to puncture the protective barrier outside the cell after expansion. In this embodiment, the insulating film 4 is located at both ends of the straight section 101 along the circumference of the cell, thereby increasing the protective barrier on the large surface of the battery and effectively protecting the weak points of the cell.

[0141] In some other embodiments, the insulating film 4 extends beyond the straight section 101 at one end along the circumference of the battery cell, while the other end of the insulating film 4 is located within the straight section 101.

[0142] The insulating film 4 is not simultaneously located at the two ends of the straight section 101 along the circumferential direction of the battery cell, so that the insulating film 4 extends at least partially to the side section 102 along the circumferential direction of the battery cell, thereby improving the ability of at least one side section 102 to resist foreign objects.

[0143] In some other embodiments, the insulating film 4 extends beyond the straight section 101 at both ends of its circumferential direction along the battery cell.

[0144] The insulating film 4 extends beyond the straight section 101 at both ends of the circumferential direction of the battery cell, so that the insulating film 4 at least partially covers the side section 102 at both ends of the circumferential direction of the battery cell, thereby protecting the side sections 102 from the risk of foreign object puncture.

[0145] In some embodiments, the battery cell includes a wound battery cell with the side section 102 being arc-shaped.

[0146] The side section 102 is the area of ​​the arc-shaped R-corner of the battery cell. The side section 102 is arc-shaped, and the stress in this area is relatively large, which makes the battery cell more prone to falling out. Therefore, an insulating film 4 is set to prevent the battery cell from falling out when punctured by foreign objects.

[0147] In some embodiments, as shown in FIG4, the separator 3 forms a separator tail portion 5 on the outer surface of the battery cell, and the insulating film 4 is attached to one side of the separator tail portion 5 on the outer surface of the battery cell.

[0148] In some embodiments, the insulating film 4 is at least partially attached to the first region 1011 and extends to the second region 1012; along the length of the cell, the length of the insulating film 4 covering the first region 1011 is b, and the length of the insulating film 4 covering the second region 1012 is a, satisfying: 0.03≤a / b≤39.

[0149] In this embodiment, the projection of at least one edge of the insulating film 4 in the direction perpendicular to the cell height is located between the positive electrode 11 and the negative electrode 12. Alternatively, the projection of at least one edge of the insulating film 4 in the direction perpendicular to the cell height is located between the negative electrode 12 and the separator 3.

[0150] The insulating film 4 is at least partially attached to the first region 1011 and extends to the second region 1012. After the insulating film 4 is attached to the first region 1011, if the insulating film 4 on one side of the first region 1011 is too short and the tape on one side of the second region 1012 is too long, the insulating film 4 attached to the second region 1012 has high viscosity, and the separator end 5 is prone to tearing when the battery is shaken. Conversely, if the insulating film 4 on one side of the second region 1012 is too short, the separator end 5 will not be firmly fixed, and there is a risk that the separator end 5 will loosen. Therefore, it is necessary to reasonably control the range of a / b.

[0151] In this embodiment, the puncture resistance f2 of the insulating film 4 can be selected from the following range: 800gf≤f2≤2040gf.

[0152] As optional parameter values, the puncture resistance f2 of the insulating film 4 can be: 800gf, 900gf, 1000gf, 1200gf, 1500gf, 1700gf, 1900gf, 2000gf, or 2040gf, etc.

[0153] In this embodiment, the length a of the insulating film 4 covering the second region 1012 is in the range of 15mm≤a≤585mm.

[0154] As an optional parameter value, the specific value of the length a of the insulating film 4 covering the second region 1012 can be: 15mm or 50mm or 100mm or 150mm or 230mm or 320mm or 390mm or 410mm or 450mm or 500mm or 515mm or 585mm, etc.

[0155] By reasonably selecting the length a of the insulating film 4 covering the second region 1012, it is ensured that the insulating film 4 can firmly fix the end part 5 of the diaphragm, preventing the end part 5 of the diaphragm from loosening, while avoiding material waste.

[0156] In this embodiment, the perimeter of the battery cell in the plane perpendicular to the height direction of the battery cell is c, which satisfies: 0.03≤a / c≤0.98.

[0157] By limiting the range of the ratio between the length a of the insulating film 4 covering the second region 1012 and the circumference c of the battery cell, it can be ensured that the length of the insulating film 4 covering the second region 1012 is sufficient, thereby ensuring that the insulating film 4 has sufficient control over the membrane termination 5.

[0158] In some embodiments, the surface with the largest area of ​​the battery cell 100 is defined as the large surface of the battery cell, and the separator 3 forms a separator tail portion 5 on the large surface of the battery cell, with the edge of the separator tail portion 5 located at 1 / 3 to 2 / 3 of the length of the battery cell along the large surface of the battery cell.

[0159] Since the central area of ​​the large surface of the battery cell is prone to expansion and is more likely to be punctured by foreign objects, the edge of the diaphragm tail section 5 is located at 1 / 3 to 2 / 3 of the length of the large surface of the battery cell to reduce the risk of foreign object puncture.

[0160] In some embodiments, the surface with the largest area of ​​the battery cell 100 is defined as the large surface of the battery cell, and the separator 3 forms a separator tail portion 5 on the large surface of the battery cell, with the edge of the separator tail portion 5 extending beyond 1 / 2 of the length of the large surface of the battery cell along the length of the battery cell.

[0161] Since the central area of ​​the large surface of the battery cell is prone to expansion, it is at greater risk of being punctured by foreign objects. By extending the edge of the separator tail 5 beyond 1 / 2 of the length of the large surface of the battery cell, the risk of foreign object puncture can be reduced, providing better protection for the positive and negative electrode plates.

[0162] In some embodiments, after the diaphragm 3 covers the electrode 1 located on the outermost layer of the cell along the thickness direction, it continues to be arranged around the circumference of the cell and the number of wrapping circles is greater than or equal to one.

[0163] When the separator 3 wraps around the cell only once, the number of separator layers is small, and the external protective barrier of the positive and negative electrodes is small. At this time, the cell 100 is more easily penetrated. In order to protect the electrodes inside the separator 3, the puncture resistance of the separator 3 needs to be strengthened.

[0164] In some other embodiments, the diaphragm 3 continues to surround the circumference of the battery cell and wraps the battery cell one to two times, and satisfies: 8gf / μm≤f1 / d1≤200gf / μm.

[0165] When the number of turns of the separator 3 around the cell is one to two, the outside of the positive and negative electrode plates has a good protective barrier, which can prevent the cell 100 from being easily penetrated to a certain extent. Therefore, the puncture resistance of the separator 3 can be appropriately reduced.

[0166] For example, in this application, the value of f1 / d1 can be 8gf / μm or 15gf / μm or 30gf / μm or 45gf / μm or 56gf / μm or 78gf / μm or 92gf / μm or 115gf / μm or 140gf / μm or 165gf / μm or 178gf / μm or 192gf / μm or 200gf / μm, or it can be any range formed by any two of the above values.

[0167] In some other embodiments, the diaphragm 3 continues to surround the circumference of the battery cell and wraps the battery cell more than two times, and satisfies: 8gf / μm≤f1 / d1≤190gf / μm.

[0168] When the number of turns of the separator 3 around the cell is more than two, the outer side of the cell 100 has a thicker separator 3 as a protective layer, which has a good anti-puncture effect on the positive and negative electrodes. At this time, the anti-puncture strength of the separator 3 can be further reduced.

[0169] For example, in this application, the value of f1 / d1 can be 8gf / μm or 15gf / μm or 30gf / μm or 45gf / μm or 56gf / μm or 78gf / μm or 92gf / μm or 115gf / μm or 140gf / μm or 165gf / μm or 178gf / μm or 190gf / μm, or it can be any range formed by any two of the above values.

[0170] In some embodiments, the diaphragm tail portion 5 covers the tail portion of the negative electrode 12. Along the length direction of the cell, the shortest distance between the edge of the diaphragm tail portion 5 and the tail portion of the negative electrode 12 is g, and the circumference of the cell is c, satisfying: 0.25≤g / c≤0.5.

[0171] When the edge of the separator 5 coincides with the edge of the negative electrode 12, the expansion of the cell 100 will create an indentation on the negative electrode 12, making it easy for material to fall off the negative electrode 12, affecting the battery's cycle performance, and also posing a risk of the material falling off and puncturing the separator 3. By limiting the value of the minimum distance g between the edge of the separator 5 and the edge of the negative electrode 12, it can be ensured that the edge of the separator 5 does not coincide with the edge of the negative electrode 12, preventing the negative electrode 12 from being squeezed and falling off.

[0172] For example, in this application, the value of g / c can be 0.25, 0.3, 0.35, 0.45, or 0.5, or it can be a range formed by any two of the above values.

[0173] In some embodiments, along the cell thickness direction, the number of layers of the separator 3 is n, and the thickness of the cell is h, satisfying: 5% ≤ d1·n / h ≤ 20%.

[0174] When d1·n / h exceeds the upper limit, the ratio is too large and the thickness of the separator 3 is too thick, making it difficult for the heat in the corner arc area of ​​the cell 100 to dissipate; when d1·n / h exceeds the lower limit, the ratio is too small and the thickness of the separator 3 is too thin, which increases the risk of the separator 3 being punctured.

[0175] For example, in this application, the value of d1·n / h can be 5%, 8%, 10%, 15%, 18%, 19%, or 20%, or it can be a range formed by any two of the above values.

[0176] In some embodiments, as shown in FIG5, the thickness of the battery cell along the thickness direction is h, which satisfies: h≥20mm and satisfies: 1≤(f2·d1) / (f1·d2)≤8.

[0177] For example, in this application, the value of (f2·d1) / (f1·d2) can be 1 or 1.2 or 1.5 or 1.8 or 2.0 or 2.5 or 2.8 or 3.0 or 3.4 or 4 or 4.2 or 5.1 or 6 or 7.4 or 8, or it can be any range formed by any two of the above values.

[0178] In some embodiments, the insulating film 4 includes insulating tape, the material of which includes PP or PET.

[0179] By selecting the above-mentioned materials, the insulation performance is guaranteed, and the puncture resistance of the insulating membrane 4 is also guaranteed. This prevents the puncture force from affecting the diaphragm 3 and causing damage to the diaphragm 3 when subjected to compression, collision, or foreign object intrusion. In this way, the positive and negative short circuits caused by diaphragm rupture are effectively prevented, thus improving safety performance.

[0180] In this embodiment, the diaphragm 3 is made of materials such as PP and PE.

[0181] In some embodiments, the insulating film 4 includes a film body and an adhesive layer adhered to one side of the film body.

[0182] In some embodiments, the insulating film 4 at least partially covers the outer surface with the largest area among the various outer surfaces of the cell 100.

[0183] Since the largest outer surface of the battery cell 100 is more susceptible to foreign object impacts, and the thermal expansion of the battery also makes it more prone to compressing the largest outer surface of the battery cell 100, it is necessary to ensure that the largest outer surface of the battery cell 100 has sufficient puncture resistance. By at least partially covering the largest outer surface of the battery cell 100 with the insulating film 4, the tensile strength of the largest outer surface of the battery cell 100 is ensured. When the largest outer surface of the battery cell 100 is subjected to compression, impact, or foreign object intrusion, the puncture force acting on the largest outer surface of the battery cell 100 can be prevented from affecting the separator 3 and causing damage to the separator 3. This effectively prevents short circuits between the positive and negative electrodes caused by separator rupture and improves safety performance.

[0184] According to an embodiment of this application, another aspect provides a battery, including at least two battery cells 100 as described above. The battery provided by the embodiments of this application, including multiple battery cells 100, by limiting the upper limit of the ratio of the puncture resistance of the insulating film 4 to the puncture resistance of the separator 3, can prevent the puncture resistance of the insulating film 4 from being too high, ensuring the insulating film 4's ability to wrap the separator 3 and the battery cells 100, avoiding the situation where the elasticity of the insulating film 4 deteriorates after the battery expands during charging and discharging, and preventing the insulating film 4 from failing to properly wrap the cells according to their expansion. Simultaneously, by limiting the lower limit of the ratio of the puncture resistance of the insulating film 4 to the puncture resistance of the separator 3, the puncture resistance of the insulating film 4 can be guaranteed, preventing damage to the separator 3 caused by puncture force when subjected to compression, collision, or foreign object intrusion, thereby effectively preventing short circuits between the positive and negative electrodes caused by separator rupture and improving safety performance.

[0185] In some embodiments, two adjacent cells 100 are bonded together, and there is at least one insulating film 4 between two adjacent cells 100, and the following condition is met: 0.1≤(f2·d1) / (f1·d2)≤7.2.

[0186] Since the two adjacent cells 100 are in close contact with each other, there are fewer foreign objects between the two adjacent cells 100 and they are not squeezed by the shell. The puncture resistance of the insulating film is less required. Therefore, when at least one insulating film 4 is provided between the two adjacent cells 100, the value range of (f2·d1) / (f1·d2) can be lower than the upper limit 9.

[0187] For example, in this application, the value of (f2·d1) / (f1·d2) can be 0.1 or 0.5 or 1 or 1.2 or 1.5 or 1.8 or 2.0 or 2.5 or 2.8 or 3.0 or 3.4 or 4 or 4.2 or 5.1 or 6 or 7.2, or it can be any of the above two values ​​forming an interval range.

[0188] In some embodiments, the battery further includes a housing 2, a battery cell 100 disposed within the housing 2, and an insulating film 4 disposed between at least one battery cell 100 and the housing 2, and satisfies: 1≤(f2·d1) / (f1·d2)≤8.5.

[0189] Since the casing 2 will squeeze the battery cell 100 when the battery cell 100 expands, when an insulating film 4 is provided between the battery cell 100 and the casing 2, the puncture resistance of the insulating film 4 is required to be relatively large, and the value range of (f2·d1) / (f1·d2) is higher than the lower limit of 0.1.

[0190] In some embodiments, the housing 2 comprises a steel shell, and satisfies: 900gf≤f2≤2050gf.

[0191] When the casing 2 is made of steel, due to the high hardness of steel, the deformation of the battery cell is relatively small when it expands and deforms. The pressure exerted by the casing on the battery cell is greater, and the range of the puncture resistance f2 of the insulating film should be appropriately larger, which should meet the requirement of 900gf≤f2≤2050gf.

[0192] Additionally, when the casing 2 is made of aluminum, due to the low hardness of aluminum, the cell has relatively good deformation ability when it expands and deforms, which can appropriately alleviate the pressure of the casing on the cell. The puncture resistance f2 of the insulating film can be appropriately reduced, and should meet the requirement of 700gf≤f2≤2000gf.

[0193] In some embodiments, two adjacent cells 100 are bonded together, and the diaphragm end portions 5 of the two adjacent cells 100 are respectively disposed on opposite sides of the bonding surface.

[0194] By setting the diaphragm tails 5 of two adjacent cells 100 on opposite sides of the bonding surface, the bonding surfaces of the two adjacent cells 100 are made more flush; this avoids indentations caused by the pressure of the two adjacent cells 100 when the diaphragm tails 5 are set on the bonding surface, and prevents material loss caused by uneven force on the electrode sheets.

[0195] In some embodiments, two adjacent battery cells 100 are in contact with each other, and the surface where the two adjacent battery cells 100 are in contact with each other is the surface with the largest area of the battery cell 100;

[0196] The tail portions 5 of the separators of two adjacent battery cells 100 are respectively arranged on the opposite surface of the contact surface.

[0197] In some embodiments, the value range of d2 satisfies: 20μm ≤ d2 ≤ 200μm.

[0198] In this embodiment, by controlling the lower limit of the thickness of the insulating film 4, the battery cell is ensured to have appropriate puncture resistance. At the same time, by controlling the upper limit of the thickness of the insulating film 4, it is avoided that the thickness of the insulating film 4 is too thick and affects the heat dissipation effect in the middle area between two adjacent battery cells 100, and at the same time, it is avoided that the energy density is reduced due to the too thick insulating film 4.

[0199] To further verify the relationship between the puncture resistance f1 of the separator 3, the thickness d1 of the separator 3, the puncture resistance f2 of the insulating film 4, and the thickness d2 of the insulating film 4, and their influence on the puncture resistance performance of the battery cell, the following is verified through several groups of examples and comparative examples.

[0200] The puncture resistance test method adopted in this embodiment: Refer to "GBT 37841-2019 Test Method for Puncture Resistance of Plastic Films and Sheets".

[0201] The battery performance detection methods adopted in this embodiment mainly include the lithium plating experiment method and the micro-short circuit experiment method. Among them, the specific experimental steps of the lithium plating experiment method are as follows:

[0202] For each group of experimental examples and comparative examples, 20 batteries are respectively prepared. After the batteries are encapsulated and injected with liquid, at room temperature (25°C), the batteries are charged in a constant current (0.05C) current mode. When the voltage reaches 3.65V, the charging is stopped, and after standing for 1 hour, the batteries are discharged at a 1C current. When the voltage reaches 2.7V, the discharge is stopped. The above batteries are disassembled and analyzed, the negative electrode plate is unfolded, and it is observed whether there are black spots on the surface of the electrode plate. If more than 90% of the 20 batteries have no black spots, it is considered qualified.

[0203] The specific experimental steps of the micro-short circuit experiment method are as follows:

[0204] For each group of experimental examples and comparative examples, 20 batteries are respectively prepared. When the batteries are put into the shell, 50um SUS particles are added between the shell and the battery cell. After the batteries are encapsulated and injected with liquid, at room temperature (25°C), the batteries are charged in a constant current (0.05C) current mode. When the voltage reaches 3.65V, the charging is stopped, and after standing for 1 hour, the batteries are discharged at a 1C current. When the voltage reaches 2.7V, the discharge is stopped.

[0205] The battery is subjected to 15KN clamping vibration and 500 CLS cycling at room temperature for self-discharge testing. The self-discharge test involves charging the battery to full capacity at 1 / 3C and then leaving it at room temperature (25℃) for 7 days. The battery capacity is then tested, and the self-discharge rate is calculated. A self-discharge rate of no more than 10% is considered acceptable.

[0206] Based on actual testing, the present application is further illustrated below with reference to Table 1 and specific embodiments:

[0207] Table 1

[0208] First, the value ranges of various parameters of the battery cell provided in this application are summarized as follows: 200gf≤f1≤800gf; 4μm≤d1≤25μm; 700gf≤f2≤2050gf; 20μm≤d2≤150μm;

[0209] Furthermore, the relationship between the parameters satisfies: 0.1≤(f2·d1) / (f1·d2)≤9.

[0210] In Examples 1 to 17, and Comparative Examples 1 to 2, the values ​​of f1, d1, f2, and d2 are all within a reasonable range.

[0211] Among them, the value of the relationship (f2·d1) / (f1·d2) in Examples 1 to 17 satisfies 0.1≤(f2·d1) / (f1·d2)≤9. After lithium plating test and micro-short circuit test, more than 90% of the 20 batteries in each example are free of black spots, which meets the pass rate requirement of lithium plating test; at the same time, the self-discharge rate of each example is not greater than 10%, which meets the pass rate requirement of micro-short circuit test.

[0212] However, in Comparative Examples 1 and 2, although the values ​​of f1, d1, f2, and d2 are all within a reasonable range, the value of the relationship (f2·d1) / (f1·d2) does not satisfy 0.1≤(f2·d1) / (f1·d2)≤9. Specifically, the value of (f2·d1) / (f1·d2) in Comparative Example 1 is greater than the upper limit. After lithium plating and micro-short circuit experiments, only 65% ​​of the 20 batteries in Comparative Example 1 are free of black spots, failing to meet the pass rate requirement for the lithium plating experiment. However, the self-discharge rate of Comparative Example 1 is no greater than 10%, meeting the pass rate requirement for the micro-short circuit experiment. In Comparative Example 2, the value of (f2·d1) / (f1·d2) is less than the lower limit. After lithium plating and micro-short circuit experiments, over 90% of the 20 batteries in Comparative Example 2 are free of black spots, meeting the pass rate requirement for the lithium plating experiment. However, the self-discharge rate of Comparative Example 2 is 80%, exceeding the 10% self-discharge pass rate requirement.

[0213] It is evident that, using Comparative Examples 1 and 2 as examples, the provided batteries cannot meet the performance test requirements when 0.1≤(f2·d1) / (f1·d2)≤9 cannot be satisfied.

[0214] According to an embodiment of this application, in another aspect, a battery module is also provided, including: the battery as described above.

[0215] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Although embodiments of this application 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 this application, and all such modifications and variations fall within the scope defined by this application.

Claims

A battery cell, characterized in that, include: Several electrode plates (1); A diaphragm (3) is disposed between the positive and negative electrode plates; The diaphragm (3) at least partially covers the outer surface of the battery cell; An insulating film (4) at least partially covers the outside of the diaphragm (3); The puncture resistance of the diaphragm (3) is defined as f1, and the thickness of the diaphragm (3) is defined as d1; the puncture resistance of the insulating film (4) is defined as f2, and the thickness of the insulating film (4) is defined as d2, satisfying: 0.1≤(f2·d1) / (f1·d2)≤9. The battery cell according to claim 1 is characterized in that, The electrode (1) includes a positive electrode (11), a negative electrode (12) and a separator (3). The separator (3) is located between the positive electrode (11) and the negative electrode (12) along the height direction of the cell. The height of the positive electrode (11) is less than the height of the negative electrode (12), and the height of the negative electrode (12) is less than the height of the separator (3). The battery cell according to claim 2 is characterized in that, Along the height direction of the cell, at least one edge of the insulating film (4) extends beyond the positive electrode plate (11). The battery cell according to claim 3 is characterized in that, Along the height direction of the cell, at least one edge of the insulating film (4) is located between the positive electrode (11) and the negative electrode (12). The battery cell according to claim 3 is characterized in that, Along the height direction of the cell, at least one edge of the insulating film (4) extends beyond the negative electrode sheet (12). The battery cell according to claim 5 is characterized in that, Along the height direction of the cell, at least one edge of the insulating film (4) is located between the negative electrode (12) and the separator (3). The battery cell according to claim 5 is characterized in that, Along the height direction of the cell, at least one edge of the insulating film (4) extends beyond the separator (3). The battery cell according to claim 2 is characterized in that, Along the height direction of the cell, both sides of the insulating film (4) extend beyond the positive electrode plate (11). The battery cell according to claim 7 is characterized in that, The insulating film (4) has at least a partial absence of adhesive layer on both sides of its edges along the height direction of the battery cell. The battery cell according to claim 1 is characterized in that, The puncture resistance f2 of the insulating film (4) is in the range of 700gf≤f2≤2050gf. The battery cell according to claim 1 is characterized in that, The battery cell has a straight section (101) and a side section (102), and the diaphragm (3) forms a diaphragm tail section (5) in the straight section (101); Along the winding direction of the diaphragm (3), the area where the surface of the battery cell is located in the straight section (101) and overlaps with the end portion (5) of the diaphragm is defined as the first region (1011), and the area where the surface of the battery cell is located in the straight section (101) and outside the end portion (5) of the diaphragm is defined as the second region (1012). The insulating film (4) is at least partially attached to the first region (1011). The battery cell according to claim 11 is characterized in that, The insulating film (4) is at least partially attached to the first region (1011) and satisfies: 0.1≤(f2·d1) / (f1·d2)≤7. The battery cell according to claim 11 is characterized in that, The insulating film (4) extends into the second region (1012) and satisfies: 1≤(f2·d1) / (f1·d2)≤9. The battery cell according to claim 11 is characterized in that, The insulating film (4) extends at least one end along the circumferential direction of the battery cell, and the edge of the insulating film (4) along the circumferential direction of the battery cell does not extend beyond the straight section (101). The battery cell according to claim 14 is characterized in that, It satisfies: 800gf≤f2≤2050gf. The battery cell according to claim 11 is characterized in that, The insulating film (4) extends at least one end along the circumferential direction of the battery cell, and the edge of the insulating film (4) along the circumferential direction of the battery cell extends beyond the straight section (101). The battery cell according to claim 16 is characterized in that, It satisfies: 700gf≤f2≤2040gf. The battery cell according to claim 16 is characterized in that, The edge of at least one end of the insulating film (4) is located between the side section (102) at half the thickness and the straight section (101). The battery cell according to claim 16 is characterized in that, The insulating film (4) is attached to the first region (1011) of the first side straight section (101), and at least one end of the insulating film (4) extends along the circumference of the cell toward the second side straight section (101), and the edge of at least one end of the insulating film (4) exceeds 1 / 2 of the thickness of the side section (102). The battery cell according to claim 19 is characterized in that, The edge of at least one end of the insulating film (4) is located between the side section (102) at half the thickness and the straight section (101) on the second side. The battery cell according to claim 16 is characterized in that, The insulating film (4) is attached to the first region (1011) of the first side of the straight section (101), and at least one end of the insulating film (4) extends along the circumference of the cell toward the second side of the straight section (101), and the edge of at least one end of the insulating film (4) extends beyond the side section (102). The battery cell according to claim 21 is characterized in that, Furthermore, the edge of at least one end of the insulating film (4) is located on the straight section (101) on the second side. The battery cell according to claim 16 is characterized in that, The side segment (102) adjacent to the first region (1011) is defined as the first side segment, and the side segment (102) adjacent to the second region (1012) is defined as the second side segment; The insulating film (4) is attached to the first region (1011) of the first side straight section (101), and at least one end of the insulating film (4) extends along the circumferential direction of the battery cell. The insulating film (4) covers the first side section and the second side straight section (101). The edge of at least one end of the insulating film (4) extends beyond the second side straight section (101). The battery cell according to claim 23 is characterized in that, The edge of at least one end of the insulating film (4) is located between the straight section (101) on the second side and half the thickness of the second side section. The battery cell according to claim 23 is characterized in that, The edge of at least one end of the insulating film (4) extends beyond half the thickness of the second side segment. The battery cell according to claim 23 is characterized in that, The edge of at least one end of the insulating film (4) is located between the second side segment at 1 / 2 of its thickness and the first side straight segment (101). The battery cell according to claim 16 is characterized in that, The side segment (102) adjacent to the first region (1011) is defined as the first side segment, and the side segment (102) adjacent to the second region (1012) is defined as the second side segment; The insulating film (4) is attached to the first region (1011) of the first side straight section (101), and at least one end of the insulating film (4) extends along the circumferential direction of the battery cell. The insulating film (4) covers the first side section and the second side straight section (101), and the edge of at least one end of the insulating film (4) extends beyond the second side section. The battery cell according to claim 14 is characterized in that, The insulating film (4) has both ends of its circumferential edge located in the straight section (101). The battery cell according to claim 16 is characterized in that, The insulating film (4) is disposed beyond the straight section (101) at one end edge along the circumference of the battery cell, and the insulating film (4) is located at the straight section (101) at the other end edge along the circumference of the battery cell. The battery cell according to claim 16 is characterized in that, The insulating film (4) extends beyond the straight section (101) at both ends of the circumferential direction of the battery cell. The battery cell according to claim 11 is characterized in that, The battery cell includes a wound battery cell, and the side section (102) is arc-shaped. The battery cell according to claim 11 is characterized in that, The insulating film (4) is at least partially attached to the first region (1011) and extends to the second region (1012); along the length of the cell, the length of the insulating film (4) covering the first region (1011) is b, and the length of the insulating film (4) covering the second region (1012) is a, satisfying: 0.03≤a / b≤39. The battery cell according to claim 32 is characterized in that, The puncture resistance f2 of the insulating film (4) is in the range of 800gf≤f2≤2040gf. The battery cell according to claim 32 is characterized in that, The length a of the insulating film (4) covering the second region (1012) is in the range of 15mm≤a≤585mm. The battery cell according to claim 32 is characterized in that, The perimeter of the battery cell in the plane perpendicular to the height direction of the battery cell is c, which satisfies: 0.03≤a / c≤0.

98. The battery cell according to claim 1 is characterized in that, The surface with the largest area of ​​the battery cell (100) is defined as the large surface of the battery cell. The separator (3) forms a separator tail portion (5) on the large surface of the battery cell, and the edge of the separator tail portion (5) is located at 1 / 3 to 2 / 3 of the length of the battery cell along the large surface of the battery cell. The battery cell according to claim 1 is characterized in that, The surface with the largest area of ​​the battery cell (100) is defined as the large surface of the battery cell. The separator (3) forms a separator tail portion (5) on the large surface of the battery cell, and the edge of the separator tail portion (5) extends beyond 1 / 2 of the length of the large surface of the battery cell. The battery cell according to claim 1 is characterized in that, After the diaphragm (3) covers the electrode (1) located on the outermost layer of the cell along the thickness direction, it continues to be arranged around the circumference of the cell and the number of wrapping circles is greater than or equal to one. The battery cell according to claim 38 is characterized in that, The diaphragm (3) continues to surround the circumference of the battery cell and wraps the battery cell for one to two turns, and satisfies: 8gf / μm≤f1 / d1≤200gf / μm. The battery cell according to claim 38 is characterized in that, The diaphragm (3) continues to surround the circumference of the battery cell and wraps the battery cell more than two times, and satisfies: 8gf / μm≤f1 / d1≤190gf / μm. The battery cell according to claim 1 is characterized in that, The surface with the largest area of ​​the battery cell (100) is defined as the large surface of the battery cell. The separator (3) forms a separator tail portion (5) on the large surface of the battery cell. The separator tail portion (5) covers the tail portion of the negative electrode sheet (12). Along the length direction of the battery cell, the shortest distance between the edge of the separator tail portion (5) and the tail portion of the negative electrode sheet (12) along the circumference of the battery cell is g. The circumference of the battery cell is c, which satisfies: 0.25≤g / c≤0.

5. The battery cell according to claim 1 is characterized in that, Along the thickness direction of the battery cell, the number of layers of the separator (3) is n, and the thickness of the battery cell is h, satisfying: 5% ≤ d1·n / h ≤ 20%. The battery cell according to claim 1 is characterized in that, Along the thickness direction of the battery cell, the thickness of the battery cell is h, which satisfies: h≥20mm, and satisfies: 1≤(f2·d1) / (f1·d2)≤8. The battery cell according to claim 1 is characterized in that, The insulating film (4) includes insulating tape, the material of which includes PP or PET. The battery cell according to claim 1 is characterized in that, The insulating film (4) includes a film body and an adhesive layer adhered to one side of the film body. The battery cell according to claim 1 is characterized in that, The insulating film (4) covers at least part of the outer surface with the largest area among the various outer surfaces of the battery cell (100), and the outer surface with the largest area among the various outer surfaces of the battery cell (100) includes the straight section (101). A battery characterized in that, It includes at least two battery cells (100) as described in any one of claims 1 to 46 above. The battery according to claim 47, characterized in that, Two adjacent cells (100) are bonded together, and there is at least one insulating film (4) between two adjacent cells (100), and the following condition is met: 0.1≤(f2·d1) / (f1·d2)≤7.

2. The battery according to claim 47, characterized in that, The battery also includes a housing (2), the battery cell (100) is disposed inside the housing (2), and at least one of the battery cells (100) is provided with an insulating film (4) between the housing (2) and the housing (2), and satisfies: 1≤(f2·d1) / (f1·d2)≤8.

5. The battery according to claim 49, characterized in that, The shell (2) includes a steel shell and satisfies: 900gf≤f2≤2050gf. The battery according to claim 49, characterized in that, Two adjacent cells (100) are bonded together, and the membrane end portions (5) of the two adjacent cells (100) are respectively disposed on the opposite sides of the bonding surface. The battery according to claim 47, characterized in that, The range of values ​​for d2 satisfies: 20μm≤d2≤200μm. A battery module, characterized in that, Includes the battery as described in any one of claims 47 to 52 above.

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