Battery cell, battery and battery module

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell, a battery and a battery module. The diaphragm is laminated with the plurality of pole pieces and is suitable for separating the plurality of pole pieces; the diaphragm at least partially coats the outer surface of the battery cell; the diaphragm forms a diaphragm ending part on the outer surface of the battery cell; one end of the insulating film is fixed on the outer side of the diaphragm ending part, and the insulating film at least partially coats the outer side of the diaphragm forming the outer surface of the battery cell; the puncture resistance of the diaphragm is defined as f1, and the thickness of the diaphragm 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, and 0.1 < = (f2d1) / (f1d2) < = 9 is satisfied. According to the battery cell provided by the invention, overhigh hardness of the insulating film can be avoided, and the wrapping capability of the insulating film on the diaphragm and the battery cell is ensured; the puncture-resistant strength of the insulating film is guaranteed, and the situation that the diaphragm is damaged due to the fact that the diaphragm is affected by puncture force when the insulating film is extruded, collided and invaded by foreign matter is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of battery cells, and in particular to a battery cell, a battery and a battery module. Background Art

[0002] The battery cell is made of positive electrode sheets, negative electrode sheets and separators that are stacked or wound. The separator is placed between the positive electrode sheets and the negative electrode sheets to achieve ion conduction and electronic insulation. Taking the wound battery cell as an example, the outermost layer of the battery cell is coated with a separator after winding, and an insulating film is attached to the outside of the separator. When the puncture resistance of the insulating film is lower than that of the separator, it cannot protect the separator from being punctured by external foreign objects.

[0003] However, if the puncture resistance of the insulating film is too great, the insulating film will be thicker and harder, and the wrapping property of the insulating film on the diaphragm will be worse. Similarly, if the puncture resistance of the diaphragm is too great, the diaphragm will be thicker and harder, which will squeeze and interfere with the battery cell at the bent part of the battery cell, causing the battery cell to fall off, and then it will be easy to puncture the diaphragm or insulating film. The rupture of the insulating film will easily cause insulation failure, and the rupture of the diaphragm will easily cause a short circuit between the positive and negative electrodes, causing safety problems. Summary of the invention

[0004] In view of this, the present invention provides a battery cell, a battery and a battery module to solve the problem that the rupture of the insulating film of the battery cell easily causes insulation failure, and the rupture of the diaphragm easily causes a short circuit between the positive and negative electrodes.

[0005] In a first aspect, the present invention provides a battery cell, comprising:

[0006] A number of pole pieces;

[0007] The diaphragm is disposed between the positive and negative electrode sheets; the diaphragm at least partially covers the outer surface of the battery cell;

[0008] An insulating film, the insulating film at least partially covering the outer side of the diaphragm;

[0009] The puncture resistance of the diaphragm is defined as f1, and the thickness of the diaphragm is defined as d1; the puncture resistance of the insulating film is defined as f2, and the thickness of the insulating film is defined as d2, satisfying: 0.1≤(f2·d1) / (f1·d2)≤9.

[0010] Beneficial effect: The battery cell provided by the embodiment of the present invention can avoid the insulating film from being too hard by limiting the upper limit of the ratio range of the puncture resistance strength of the insulating film to the puncture resistance strength of the diaphragm, ensure the ability of the insulating film to wrap the diaphragm and the battery cell, avoid the situation where the elasticity of the insulating film deteriorates after the battery is expanded during charge and discharge, and prevent the insulating film from being unable to wrap snugly according to the expansion of the battery cell. At the same time, by limiting the lower limit of the ratio range of the puncture resistance strength of the insulating film to the puncture resistance strength of the diaphragm, the puncture resistance strength of the insulating film can be guaranteed, and when it is squeezed, collided, or invaded by foreign objects, the puncture force is prevented from affecting the diaphragm and causing damage to the diaphragm, thereby effectively preventing the positive and negative short circuits caused by diaphragm rupture, thereby improving safety performance.

[0011] In a second aspect, the present invention further provides a battery, comprising: at least two battery cells as described above.

[0012] Since the battery includes a cell and has the same effect as the cell, it will not be described in detail here.

[0013] In a third aspect, the present invention further provides a battery module, comprising: the battery as described above.

[0014] Since the battery module includes a battery cell and has the same effect as the battery cell, it will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a schematic cross-sectional view of a first type of battery cell of the present invention in a direction perpendicular to the height;

[0017] Figure 2 It is a schematic cross-sectional view of a second type of battery cell of the present invention in a direction perpendicular to the height;

[0018] Figure 3 Schematic diagram of a cross section of a battery cell coated with an insulating film in the present invention perpendicular to the height direction Figure 1 ;

[0019] Figure 4 The cross section of the battery cell coated with an insulating film according to the present invention is perpendicular to the height direction. Figure 2 ;

[0020] Figure 5 is a schematic diagram of a battery of the present invention;

[0021] Figure 6 It is a schematic diagram of a battery cell coated with an insulating film in a direction perpendicular to the thickness of the present invention.

[0022] Description of reference numerals:

[0023] 1. Pole piece; 11. Positive electrode piece; 12. Negative electrode piece; 2. Shell; 3. Diaphragm; 4. Insulating film; 5. Diaphragm tail; 100. Battery cell; 101. Straight section; 1011. First region; 1012. Second region; 102. Side section. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] The battery cell is formed by stacking or winding the positive electrode sheet, the negative electrode sheet and the separator, and the separator is placed between the positive electrode sheet and the negative electrode sheet to achieve ion conduction and electronic insulation. Taking the wound battery cell as an example, the outermost layer of the battery cell is coated with a separator after winding, and an insulating tape is attached to the outside of the separator. When the battery is squeezed, collided, or invaded by foreign objects, it is easy to puncture the insulating film and / or the separator. The rupture of the insulating film is easy to cause insulation failure, and the rupture of the separator is easy to cause a short circuit between the positive and negative electrodes, causing safety problems. Therefore, it is necessary to ensure that the insulating film and the separator have appropriate puncture resistance. In order to reduce the situation where the insulating film and / or the separator are easily punctured when the battery is squeezed, collided, or invaded by foreign objects, thereby avoiding the insulation failure caused by the rupture of the insulating film, and at the same time avoiding the short circuit of the positive and negative electrodes caused by the rupture of the separator, and improving the safety performance of the battery cell.

[0029] Combine the following Figures 1 to 6 , describing an embodiment of the present invention.

[0030] According to an embodiment of the present invention, on one hand, a battery cell 100 is provided, comprising:

[0031] A plurality of pole pieces 1;

[0032] The diaphragm 3 is disposed between the positive and negative electrode sheets; the diaphragm 3 at least partially covers the outer surface of the battery cell;

[0033] An insulating film 4, the insulating film 4 at least partially covers the outer side of the diaphragm 3;

[0034] 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:

[0035] 0.1≤(f2·d1) / (f1·d2)≤9.

[0036] It should be noted that the battery cell 100 includes a plurality of pole pieces 1 , specifically, the battery cell 100 includes at least two layers of pole pieces 1 .

[0037] In this embodiment, the battery cell 100 is formed by stacking or winding a positive electrode sheet 11, a negative electrode sheet 12 and a separator 3. The battery cell 100 can be a wound battery cell or a laminated battery cell. The wound battery cell includes a positive electrode sheet 11 and a negative electrode sheet 12, with a separator 3 between the positive electrode sheet 11 and the negative electrode sheet 12, and is formed into a battery cell by continuous winding to become the smallest charging and discharging unit. The laminated battery cell includes a positive electrode sheet 11 and a negative electrode sheet 12, with a separator 3 between the positive electrode sheet 11 and the negative electrode sheet 12, and is formed into a continuous laminate by stacking, and the continuous laminate is cut into a plurality of laminate units, and then the laminate units are stacked to form a laminated battery cell.

[0038] As one of the implementation forms, combined with Figure 1As shown, the battery cell is formed by stacking the positive electrode sheet 11, the negative electrode sheet 12 and the separator 3 in sequence, and the positive electrode sheet 11 and the negative electrode sheet 12 are arranged alternately, that is, the electrode sheets adjacent to the positive electrode sheet 11 on both sides of the stacking direction are the negative electrode sheets 12, and the electrode sheets adjacent to the negative electrode sheet 12 on both sides of the stacking direction are the positive electrode sheets 11. A separator 3 is arranged between every two adjacent electrode sheets 1, and the separator 3 can be a continuous film structure or a non-continuous film structure arranged layer by layer.

[0039] As another implementation, combining Figure 2 As shown, the battery cell is formed by winding the positive electrode sheet 11, the negative electrode sheet 12 and the separator 3, with one of the positive electrode sheet 11 and the negative electrode sheet 12 as the winding center, and the separator 3 is continuously wound, and after the winding is completed, the positive electrode sheet 11 and the negative electrode sheet 12 are arranged alternately, that is, the adjacent electrode sheets on both sides of the positive electrode sheet 11 along the stacking direction are all negative electrode sheets 12, and the adjacent electrode sheets on both sides of the negative electrode sheet 12 along the stacking direction are all positive electrode sheets 11. A separator 3 is arranged between every two adjacent electrode sheets 1.

[0040] After a predetermined number of positive electrode sheets 11 and negative electrode sheets 12 are stacked, the shape of the battery cell 100 is basically formed. At this time, the diaphragm 3 continues to be wound around the battery cell 100 for more than one circle, so that the diaphragm 3 can at least partially cover the outer surface of the battery cell, thereby preventing the positive electrode sheet 11 or the negative electrode sheet 12 from being directly exposed on the outermost layer of the battery cell 100, so that the diaphragm 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, that is, the ratio of the puncture resistance strength of the insulating film 4 to the puncture resistance strength of the diaphragm 3.

[0042] In this embodiment, both the insulating film 4 and the diaphragm 3 need to have sufficient puncture resistance to ensure that the battery cell 100 is not affected by external impurities or particulate matter, and further by limiting the range of (f2·d1) / (f1·d2), that is, the ratio range of the puncture resistance of the insulating film 4 to the puncture resistance of the diaphragm 3. When the ratio range is too large, the puncture resistance of the insulating film 4 will be too large, and the wrapping ability of the diaphragm 3 and the battery cell 100 will be reduced. At the same time, the elasticity of the insulating film 4 will deteriorate after the battery is charged and discharged and expanded, and it is impossible to wrap it tightly according to the expansion of the battery cell, which may lead to insufficient restraint on the battery cell 100. When the above ratio range is too small, the puncture resistance of the insulating film 4 is weak. When it is squeezed, collided, or invaded by foreign objects, the puncture force will affect the diaphragm 3, causing damage to the diaphragm 3, and then the diaphragm will easily rupture, resulting in a short circuit between the positive and negative electrodes, causing safety problems.

[0043] The battery cell 100 provided by the embodiment of the present invention can avoid the puncture resistance of the insulating film 4 being too large by limiting the upper limit of the ratio range of the puncture resistance of the insulating film 4 to the puncture resistance of the diaphragm 3, ensure the wrapping ability of the insulating film 4 to the diaphragm 3 and the battery cell 100, avoid the situation where the elasticity of the insulating film 4 deteriorates after the battery is expanded during charging and discharging, and prevent the insulating film 4 from being unable to wrap snugly according to the expansion of the battery cell. At the same time, by limiting the lower limit of the ratio range of the puncture resistance of the insulating film 4 to the puncture resistance of the diaphragm 3, the puncture resistance of the insulating film 4 can be guaranteed, and when it is squeezed, collided, or invaded by foreign objects, the puncture force is prevented from affecting the diaphragm 3 and causing damage to the diaphragm 3, thereby effectively preventing the positive and negative short circuits caused by the diaphragm rupture, thereby improving safety performance.

[0044] Illustratively, in the present invention, 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 an interval range formed by any two of the above values.

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

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

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

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

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

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

[0051] In a further preferred 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 specifically 5 micrometers, 6 micrometers, 7 micrometers, 9 micrometers, 11 micrometers, 12 micrometers, 15 micrometers, 17 micrometers, 19 micrometers, 20 micrometers, etc.

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

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

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

[0056] As an optional parameter value, the puncture resistance f2 of the insulating film 4 can be specifically 800 gf or 900 gf or 1000 gf or 1200 gf or 1500 gf or 1700 gf or 1900 gf or 2000 gf or 2040 gf, 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 specifically: 20 microns, 23 microns, 24 microns, 35 microns, 46 microns, 57 microns, 79 microns, 92 microns, 110 microns, 125 microns, 150 microns, etc.

[0059] In a further preferred 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 specifically: 25 micrometers, 27 micrometers, 29 micrometers, 35 micrometers, 46 micrometers, 57 micrometers, 79 micrometers, 92 micrometers, 98 micrometers, 100 micrometers, etc.

[0061] In a further preferred embodiment, the value range of (f2·d1) / (f1·d2) satisfies: 1≤(f2·d1) / (f1·d2)≤7.

[0062] Illustratively, in the present invention, 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, etc., or it can be an interval range formed by any two of the above values.

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

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

[0065] During charging, Li+ is deintercalated from the positive electrode and embedded in the negative electrode. If there is not enough space in the negative electrode and insufficient space for lithium embedding, the resistance to Li+ embedding in the negative electrode will increase, causing the Li+ that cannot be embedded in the negative electrode to gain electrons on the surface of the negative electrode, forming lithium deposition, which ultimately reduces the performance of the lithium battery and greatly shortens the cycle life.

[0066] In this embodiment, along the height direction of the battery cell, by making the height of the positive electrode sheet 11 smaller than the height of the negative electrode sheet 12, the occurrence of lithium deposition can be reduced, thereby ensuring the performance of the battery and preventing the cycle life from being greatly shortened. And by making the height of the negative electrode sheet 12 smaller than the height of the diaphragm 3, the diaphragm 3 is ensured to play an insulating role, avoiding the positive and negative electrode sheets from overlapping and causing a short circuit.

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

[0068] By making at least one side edge of the insulating film 4 exceed the positive electrode sheet 11 , it is possible to prevent the edge of the insulating film 4 from squeezing the positive electrode sheet 11 when the battery expands, thereby preventing the positive electrode sheet 11 from falling off.

[0069] The height of the insulating film 4 along the height direction of the battery cell is greater than the height of the positive electrode sheet 11, and the insulating film 4 can completely cover the positive electrode sheet 11 along the height direction of the battery cell. When the insulating film 4 is only attached to the negative electrode sheet 12, the insulating film 4 will squeeze the negative electrode sheet 12 after the battery cell 100 expands, causing the negative electrode sheet 12 to drop, affecting the battery cycle performance, and there is a risk of the drop puncturing the diaphragm 3. In this embodiment, at least one side edge of the insulating film 4 exceeds the positive electrode sheet 11 along the height direction of the battery cell, which can avoid the situation where the insulating film 4 squeezes the negative electrode sheet 12 after the battery cell 100 expands, causing the negative electrode sheet 12 to drop. In addition, since the height of the positive electrode sheet 11 is less than the height of the negative electrode sheet 12, that is, there is a missing electrode sheet in the area above the positive electrode sheet 11 and below the negative electrode sheet 12 along the height direction of the battery cell, the edge of the insulating film 4 is attached to this position to fill the missing position of the negative electrode sheet without taking up space. In addition, the edge of the insulating film 4 is attached to this position to provide a certain support force for the positive electrode sheet 11 and the diaphragm 3, so that the insulating film 4 is also better fitted.

[0070] As an optional implementation form, along the height direction of the battery cell, both side edges of the insulating film 4 exceed the positive electrode sheet 11.

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

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

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

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

[0075] Along the height direction of the battery cell, since the height of the positive electrode sheet 11 is smaller than the height of the negative electrode sheet 12, at least one side edge of the insulating film 4 exceeds the negative electrode sheet 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 sheet 12 when the battery expands, thereby preventing the negative electrode sheet 12 from falling off.

[0076] As an optional implementation, along the height direction of the battery cell, both side edges of the insulating film 4 exceed the negative electrode sheet 12 .

[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 sheet 11 and the negative electrode sheet 12. The insulating film 4 can completely cover the positive electrode sheet 11 and the negative electrode sheet 12 along the height direction of the battery cell, avoiding the short circuit between the positive and negative electrodes caused by being punctured by the diaphragm 3, and is safer.

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

[0079] When the insulating film 4 exceeds the edge of the diaphragm 3, due to the lack of shielding of the battery cell, if the edge is glued during assembly, it will stick to other battery components or foreign objects, thereby interfering with smooth assembly and posing certain safety hazards. By arranging at least one side edge of the insulating film 4 between the negative electrode sheet 12 and the diaphragm 3, it can be avoided that the insulating film 4 exceeds the diaphragm 3 and sticks to external foreign objects during assembly.

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

[0081] In some other embodiments, along the height direction of the battery cell, at least one side edge of the insulating film 4 exceeds the diaphragm 3 .

[0082] By making at least one side edge of the insulating film 4 exceed the separator 3, the entire surface of the battery cell can be protected to prevent the separator 3 from being damaged, thereby preventing the positive and negative electrodes from being damaged or causing a short circuit.

[0083] As an optional implementation form, along the height direction of the battery cell, both side edges of the insulating film 4 exceed the diaphragm 3 .

[0084] In some embodiments, along the height direction of the battery cell, both side edges of the insulating film 4 exceed the positive electrode sheet 11 .

[0085] By making the edges of both sides of the insulating film 4 exceed the positive electrode sheet 11, it can be ensured that both ends of the positive electrode sheet 11 along the height direction of the battery cell are protected, and the insulating film 4 at both ends will not be pressed onto the positive electrode sheet 11 due to battery expansion, thereby preventing the positive electrode sheet 11 from falling off, thereby avoiding affecting the positive and negative electrode pathways.

[0086] In some embodiments, at least part of the two side edges of the insulating film 4 along the height direction of the battery cell do not contain a glue layer.

[0087] In order to prevent the insulating film 4 from sticking to foreign matter when being assembled after it extends beyond the diaphragm 3 , in this embodiment, both side edges of the insulating film 4 along the height direction of the battery cell are at least partially free of glue layer, thereby ensuring smooth assembly and reducing safety hazards.

[0088] The height of the insulating film 4 along the height direction of the battery cell is greater than the height of the diaphragm 3. When the insulating film 4 exceeds the edge, due to the lack of shielding of the battery cell, if the edge is assembled with glue, it will stick to other battery components or foreign objects, thereby interfering with smooth assembly and posing certain safety hazards. In this embodiment, the upper and lower edges of the insulating film 4 along the height direction of the battery cell at least partially do not contain a glue layer, which can ensure smooth assembly and reduce safety hazards.

[0089] In some embodiments, the puncture resistance f2 of the insulating film 4 has a value range of: 700 gf≤f2≤2050 gf.

[0090] When the puncture resistance of the insulating film 4 is too high, the insulating film 4 will be too hard and unable to wrap the battery cell tightly. At the same time, the battery cell will be squeezed at the corner where the stress is large, causing lithium deposition. When the puncture resistance of the insulating film 4 is too low, foreign matter can easily puncture the insulating film 4 and then damage the diaphragm 3, causing a short circuit in the battery, which poses a certain safety hazard.

[0091] This embodiment limits the upper and lower limits of the puncture resistance f2 of the insulating film 4, so that the insulating film 4 can better wrap the battery cell and avoid squeezing the battery cell at the corner where the stress is large to cause lithium deposition; at the same time, it can reduce the possibility that foreign matter can easily puncture the insulating film 4 and then damage the diaphragm 3.

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

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

[0094] Along the winding direction of the separator 3, the area on the cell surface located in the straight section 101 and overlapping with the separator tail portion 5 is defined as the first area 1011, and the area on the cell surface located in the straight section 101 and outside the separator tail portion 5 is defined as the second area 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 area 1011 of 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 being affected by foreign matter.

[0097] In this embodiment, the battery cell 100 is defined as having a straight section 101. For a laminated battery, the area between the two ends along the length of the battery cell is the straight section 101; and for a wound battery, the straight section 101 is the area without the outer curved R corner. The area with the curved R corner is the side section 102. In this embodiment, along the length direction of the battery cell, the side sections 102 are arranged on both sides of the straight section 101, and along the thickness direction of the battery cell, the straight section 101 is formed on both sides.

[0098] Since the diaphragm 3 usually does not have adhesive properties, the diaphragm tail portion 5 cannot be completely fitted and fixed to the battery cell 100. By further wrapping the insulating film 4 on the outside of the diaphragm 3, one end of the insulating film 4 is fixed to the outside of the diaphragm tail portion 5, and the insulating film 4 is further wrapped on the outer surface of the battery cell, so that the insulating film 4 is at least partially covered on the outside of the diaphragm 3 forming the outer surface of the battery cell, on the one hand, the diaphragm tail portion 5 of the diaphragm 3 can be fixed, and on the other hand, the insulation performance of the outermost layer of the battery cell 100 can be further improved, which plays a role in protecting the diaphragm 3 and the pole piece 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 diaphragm 3 forms a diaphragm tail portion 5 in the straight section 101 of the battery cell. The diaphragm tail portion 5 is located in the first area 1011 of the battery cell. The diaphragm tail portion 5 can serve as a protective barrier outside the battery cell. At this time, the protective barrier of the first area 1011 has one more layer than that of the second area 1012, and there are more external protective barriers for the positive and negative electrodes. Therefore, the anti-puncture emphasis of the insulating film 4 attached to the first area 1011 can be appropriately reduced. At this time, the value range of (f2·d1) / (f1·d2) is lower than the upper limit.

[0101] Illustratively, in the present invention, 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, etc., or it can be an interval range formed by any two of the above values.

[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 diaphragm 3, the diaphragm 3 forms a diaphragm tail portion 5 in the straight section 101 of the battery cell. The diaphragm tail portion 5 located in the first area 1011 of the battery cell can serve as a protective barrier to the outside of the battery cell, while the second area 1012 of the battery cell lacks a layer of diaphragm 3 as a protective barrier. At this time, the second area 1012 has fewer external protective barriers for the positive and negative electrodes, so the puncture resistance of the diaphragm 3 must be strengthened to ensure that the internal battery cell is not affected by foreign objects. At this time, the value range of (f2·d1) / (f1·d2) is higher than the lower limit.

[0104] Illustratively, in the present invention, 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, etc., or it can be an interval range formed by any two of the above values.

[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 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 .

[0106] In this embodiment, 800gf≤f2≤2050gf is satisfied.

[0107] Since the large surface of the battery is more likely to expand, foreign matter can more easily pierce the protective barrier outside the battery cell after expansion. In this embodiment, the protective barrier of the large surface of the battery is increased by extending at least one end of the insulating film 4 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.

[0108] In addition, the puncture resistance of the insulating film 4 is greater, thereby enhancing the protection of the large surface of the battery.

[0109] In some 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 along the circumference of the battery cell, and the edge of the insulating film 4 along the circumference of the battery cell exceeds the straight section 101 .

[0110] In this embodiment, 700gf≤f2≤2040gf is satisfied.

[0111] The edge of the insulating film 4 along the circumference of the battery cell exceeds the straight section 101, that is, the insulating film 4 extends to the side section 102 along the circumference of the battery cell. The side section 102 is also the area of ​​the arc R angle of the battery cell. The stress in this area is relatively large, so the insulating film 4 is difficult to adhere and coat, and it is easy to warp. If the puncture resistance of the insulating film 4 is too large, the insulating film is too hard, which is not conducive to the coating of the insulating film 4 on the side section 102. Therefore, when the edge of the insulating film 4 along the circumference of the battery cell exceeds the straight section 101, it is necessary to lower the upper limit of the value 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 along the circumference of the battery cell, and the edge of the insulating film 4 along the circumference of the battery cell exceeds the straight section 101, and the edge of at least one end of the insulating film 4 is located between 1 / 2 of the thickness of the side section 102 and the straight section 101.

[0113] When the edge of the insulating film 4 is within 1 / 2 of the thickness of the side segment 102, less insulating film 4 is attached to the side segment 102 and is more likely to warp, so the puncture resistance of the insulating film 4 should be appropriately reduced.

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

[0115] The edge of at least one end of the insulating film 4 exceeds ½ of the thickness of the side segment 102 . At this time, the insulating film 4 covers most of the side segment 102 to protect the side segment 102 .

[0116] In some other embodiments, the insulating film 4 is attached to the first region 1011 of the first side straight segment 101, at least one end of the insulating film 4 extends toward the second side straight segment 101 along the circumference of the battery cell, and the edge of the insulating film 4 along the circumference of the battery cell exceeds the straight segment 101, and the edge of at least one end of the insulating film 4 is located between 1 / 2 of the thickness of the side segment 102 and the second side straight segment 101.

[0117] The edge of at least one end of the insulating film 4 is located between 1 / 2 of the thickness of the side segment 102 and the second side straight segment 101 . At this time, the insulating film 4 covers most of the side segment 102 to protect the side segment 102 .

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

[0119] The edge of at least one end of the insulating film 4 is disposed beyond the side segment 102 . At this time, the insulating film 4 completely wraps the side segment 102 , thus having a better protective effect on the side segment 102 .

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

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

[0122] At this time, the insulating film 4 also protects the second side straight section 101 of the battery cell, and can effectively protect the contact surface between the battery cell and the shell, as well as the contact surface between the battery cell and another battery cell, to prevent puncture by foreign objects.

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

[0124] The insulating film 4 is attached to the first area 1011 of the first side straight section 101, and 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 segment, the insulating film 4 covers the second side straight section 101, and the edge of at least one end of the insulating film 4 is set 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 area 1011 of the first side straight section 101, and the insulating film 4 covers the second area 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 completely covers the second side straight section 101 of the battery cell, which can better prevent foreign matter from piercing 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 1 / 2 of 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 area 1011 of the first side straight segment 101, and the insulating film 4 covers the second area 1012 of the first side straight segment 101, covers the first side segment, covers the second side straight segment 101, and at least partially covers the second side segment; so that the edge of the second end of the insulating film 4 is located between the second side straight segment 101 and 1 / 2 of the thickness of the second side segment.

[0129] At this time, the insulating film 4 completely covers the second side straight section 101 of the battery cell, which can better ensure that foreign objects will not pierce the diaphragm, and plays a certain protective role on the second side section, protecting the second side section from being affected by foreign objects.

[0130] In some other embodiments, the edge of at least one end of the insulating film 4 exceeds 1 / 2 of 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 area 1011 of the first side straight segment 101, and the insulating film 4 covers the second area 1012 of the first side straight segment 101, covers the first side segment, covers the second side straight segment 101, and at least partially covers the second side segment; so that the edge of the second end of the insulating film 4 exceeds 1 / 2 of the thickness of the second side segment.

[0132] At this time, the insulating film 4 fully covers the second side straight section 101 of the battery cell, which can better ensure that foreign matter will not pierce the diaphragm. The second side section is more covered to protect the second side section from foreign matter, further increasing the ability of the second side section to resist foreign matter.

[0133] In some other embodiments, the edge of at least one end of the insulating film 4 is located between 1 / 2 of the thickness of the second side segment and the first side straight segment 101 .

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

[0135] At this time, the insulating film 4 fully covers the second side straight section 101 of the battery cell, which can better ensure that foreign matter will not pierce the diaphragm. The second side section is more covered to protect the second side section from foreign matter, further increasing the ability of the second side section to resist foreign matter.

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

[0137] The insulating film 4 is attached to the first area 1011 of the first side straight section 101, and 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 segment, the insulating film 4 covers the second side straight section 101, and the edge of at least one end of the insulating film 4 exceeds the second side segment.

[0138] In this embodiment, the edge of the first end of the insulating film 4 is attached to the first area 1011 of the first side straight segment 101, and the insulating film 4 covers the second area 1012 of the first side straight segment 101, and covers the first side segment, and covers the second side straight segment 101, and covers the second side segment, so that the insulating film 4 wraps around the first side straight segment 101 again, so that the insulating film 4 wraps most of or the entire battery cell, and the battery cell's ability to resist foreign matter is enhanced.

[0139] In some other embodiments, both end edges of the insulating film 4 along the circumference of the battery cell are located in the straight section 101 .

[0140] Since the large surface of the battery is the most severely expanded area, foreign matter is more likely to pierce the protective barrier outside the battery cell after expansion. In this embodiment, the edges of both ends of the insulating film 4 along the circumference of the battery cell are located in the straight section 101, thereby increasing the protective barrier of the large surface of the battery and effectively protecting the weak points of the battery cell.

[0141] In some other embodiments, one end edge of the insulating film 4 along the circumference of the battery cell is disposed beyond the straight section 101 , and the other end edge of the insulating film 4 along the circumference of the battery cell is located in the straight section 101 .

[0142] The two end edges of the insulating film 4 along the circumference of the battery cell are not in the straight section 101 at the same time, so that the insulating film 4 at least partially extends to the side section 102 along the circumference of the battery cell, which can improve the ability of at least one side of the side section 102 to resist foreign matter.

[0143] In some other embodiments, both end edges of the insulating film 4 along the circumference of the battery cell are disposed beyond the straight section 101 .

[0144] The edges of both ends of the insulating film 4 along the circumference of the battery cell are arranged beyond the straight section 101, so that both ends of the insulating film 4 along the circumference of the battery cell at least partially cover the side sections 102, so that the insulating film 4 can protect the side sections 102 on both sides from the risk of puncture by foreign objects.

[0145] In some embodiments, the battery cell includes a wound battery cell, and the side segment 102 is arc-shaped.

[0146] The side segment 102 is also the area of ​​the arc R angle of the battery cell. The side segment 102 is arc-shaped, and the stress in this area is relatively large, which makes the battery cell more likely to fall off. Therefore, an insulating film 4 is provided to prevent the battery cell from falling off when punctured by foreign objects.

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

[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 direction of the battery cell, the length b of the insulating film 4 covering the first region 1011 is, and the length a of the insulating film 4 covering the second region 1012 is, satisfying: 0.03≤a / b≤39.

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

[0150] The insulating film 4 is at least partially attached to the first area 1011 and extends to the second area 1012; after the insulating film 4 is attached to the first area 1011, if the insulating film 4 adhered to one side of the first area 1011 is too short and the tape on one side of the second area 1012 is too long, the insulating film 4 attached to the second area 1012 has a high viscosity and the diaphragm tail 5 is easily torn when the battery is shaken; conversely, if the insulating film 4 adhered to one side of the second area 1012 is too short, the diaphragm tail 5 cannot be firmly fixed, and there is a risk of the diaphragm tail 5 loosening, so it is necessary to reasonably control the range of a / b.

[0151] In this embodiment, a further preferred value range of the puncture resistance f2 of the insulating film 4 is: 800 gf≤f2≤2040 gf.

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

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

[0154] As an optional parameter value, the specific value of the length a of the insulating film 4 covering the second area 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 properly selecting a value for 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 membrane tail portion 5 , preventing the membrane tail portion 5 from loosening, while avoiding material waste.

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

[0157] By limiting the ratio range of the length a of the insulating film 4 covering the second area 1012 to the circumference c of the battery cell, it can be ensured that the insulating film 4 covers a sufficient length of the second area 1012, thereby ensuring that the insulating film 4 has sufficient control over the diaphragm tail portion 5.

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

[0159] Since the middle area of ​​the large surface of the battery cell is easy to expand and has a greater risk of being punctured by foreign objects, the edge of the diaphragm tail portion 5 is located at 1 / 3 to 2 / 3 of the large surface of the battery cell along the length of the battery cell, which can reduce the risk of foreign object puncture.

[0160] In some embodiments, the largest surface of the battery cell 100 is defined as the large surface of the battery cell, the diaphragm 3 forms a diaphragm tail portion 5 on the large surface of the battery cell, and the edge of the diaphragm tail portion 5 exceeds the 1 / 2 position of the large surface of the battery cell along the length direction of the battery cell.

[0161] Since the middle area of ​​the large surface of the battery cell is prone to expansion, the risk of puncture by foreign objects is greater. By extending the edge of the diaphragm tail 5 beyond the 1 / 2 position of the large surface of the battery cell along the length of the battery cell, the risk of puncture by foreign objects can be reduced, and the positive and negative electrodes can be better protected.

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

[0163] When the diaphragm 3 wraps the battery cell only once, the number of diaphragm wrapping layers is small, and the external protective barriers of the positive and negative electrodes are small. At this time, the battery cell 100 is more easily penetrated. In order to protect the electrode on the inner side of the diaphragm 3, the puncture resistance of the diaphragm 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 for one to two turns, and satisfies: 8 gf / μm≤f1 / d1≤200 gf / μm.

[0165] When the separator 3 wraps around the battery cell one to two times, the outside of the positive and negative electrode sheets have a good protective barrier, which can prevent the battery cell 100 from being easily penetrated to a certain extent, so the puncture resistance of the separator 3 can be appropriately reduced.

[0166] Exemplarily, in the present invention, 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, etc., or it can be an interval range formed by any two of the above values.

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

[0168] When the number of turns of the separator 3 wrapped around the battery cell is greater than two, a thicker separator 3 is provided on the outside of the battery cell 100 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] Exemplarily, in the present invention, 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, etc., or it can be an interval 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 sheet 12. Along the length direction of the battery cell, the shortest distance between the edge of the diaphragm tail portion 5 and the tail portion of the negative electrode sheet 12 is g, and the circumference of the battery cell is c, satisfying: 0.25≤g / c≤0.5.

[0171] When the edge of the separator tail portion 5 overlaps with the edge of the negative electrode sheet 12, the negative electrode sheet 12 will be indented after the battery cell 100 expands, which can easily cause the negative electrode sheet 12 to fall off, affecting the battery cycle performance, and there is a risk of the falling material puncturing the separator 3. By limiting the value of the shortest distance g between the edge of the separator tail portion 5 and the tail portion of the negative electrode sheet 12, it can be ensured that the edge of the separator tail portion 5 does not overlap with the edge of the negative electrode sheet 12, thereby preventing the negative electrode sheet 12 from being squeezed and falling off.

[0172] Exemplarily, in the present invention, the value of g / c can be 0.25 or 0.3 or 0.35 or 0.45 or 0.5, etc., or can be an interval range formed by any two of the above values.

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

[0174] When d1·n / h exceeds the upper limit, the ratio is too large, which may cause the thickness of the diaphragm 3 to be too thick, making it difficult to dissipate the heat in the corner arc area of ​​the battery cell 100; when d1·n / h exceeds the lower limit, the ratio is too small, which may cause the thickness of the diaphragm 3 to be too thin, increasing the risk of puncture of the diaphragm 3.

[0175] Exemplarily, in the present invention, the value of d1·n / h may be 5% or 8% or 10% or 15% or 18% or 19% or 20%, etc., or may be an interval formed by any two of the above values.

[0176] In some embodiments, in combination Figure 5 As shown, along the thickness direction of the battery cell, the thickness of the battery cell is h, satisfying: h≥20mm and satisfying: 1≤(f2·d1) / (f1·d2)≤8.

[0177] Illustratively, in the present invention, 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, etc., or it can be an interval range formed by any two of the above values.

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

[0179] The above-mentioned materials are selected to ensure the insulation performance while ensuring the puncture resistance of the insulating film 4, so that when it is squeezed, collided, or invaded by foreign objects, it can prevent the puncture force from affecting the diaphragm 3 and causing damage to the diaphragm 3, thereby effectively preventing the positive and negative poles from being short-circuited due to diaphragm rupture, thereby improving safety performance.

[0180] In this embodiment, the material of the diaphragm 3 includes PP, PE and the like.

[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 outer surfaces of the battery cell 100 .

[0183] Since the outer surface with the largest area among all the outer surfaces of the battery cell 100 is more susceptible to the influence of foreign matter, and the battery is also more likely to squeeze the outer surface with the largest area among all the outer surfaces of the battery cell 100 due to thermal expansion, it is necessary to ensure that the outer surface with the largest area among all the outer surfaces of the battery cell 100 has sufficient puncture resistance. By at least partially covering the outer surface with the largest area among all the outer surfaces of the battery cell 100 with the insulating film 4, the tensile strength of the outer surface with the largest area among all the outer surfaces of the battery cell 100 is ensured. When the outer surface with the largest area among all the outer surfaces of the battery cell 100 is squeezed, collided, or invaded by foreign matter, the puncture force acting on the outer surface with the largest area among all the outer surfaces of the battery cell 100 can be prevented from affecting the diaphragm 3 and causing damage to the diaphragm 3, thereby effectively preventing the positive and negative short circuits caused by the diaphragm rupture, thereby improving the safety performance.

[0184] According to an embodiment of the present invention, on the other hand, a battery is also provided, comprising: at least two battery cells 100 as described above. The battery provided by the embodiment of the present invention comprises a plurality of battery cells 100. 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 diaphragm 3, it is possible to avoid the puncture resistance strength of the insulating film 4 being too large, ensure the wrapping ability of the insulating film 4 to the diaphragm 3 and the battery cell 100, avoid the situation where the elasticity of the insulating film 4 deteriorates after the battery is expanded during charge and discharge, and prevent the insulating film 4 from being unable to wrap well according to the expansion of the battery cell. 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 diaphragm 3, it is possible to ensure the puncture resistance strength of the insulating film 4, and prevent the puncture force from affecting the diaphragm 3 and causing damage to the diaphragm 3 when it is squeezed, collided, or invaded by foreign objects, thereby effectively preventing the positive and negative short circuits caused by the diaphragm rupture, thereby improving the safety performance.

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

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

[0187] Illustratively, in the present invention, 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, etc., or it can be an interval range formed by any two of the above values.

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

[0189] Since the shell 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 shell 2, the puncture resistance of the insulating film 4 is required to be relatively high, 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 includes a steel shell and satisfies: 900gf≤f2≤2050gf.

[0191] When the shell 2 is a steel shell, due to the high hardness of the steel shell, the deformation of the battery cell is relatively small when it expands and deforms, and the shell exerts greater pressure on the battery cell. The range of the puncture resistance f2 of the insulating film should be appropriately larger, and should satisfy 900gf≤f2≤2050gf.

[0192] In addition, when the shell 2 is an aluminum shell, due to the low hardness of the aluminum shell, the deformation ability of the battery cell is relatively good when it expands and deforms, which can appropriately alleviate the squeezing of the shell on the battery cell, and the puncture resistance f2 of the insulating film can be appropriately reduced, which should meet 700gf≤f2≤2000gf.

[0193] In some embodiments, two adjacent battery cells 100 are bonded to each other, and the separator tail portions 5 of the two adjacent battery cells 100 are respectively disposed on opposite surfaces of the bonding surfaces.

[0194] By setting the diaphragm tail portions 5 of two adjacent battery cells 100 on the opposite sides of the bonding surface, the bonding surfaces of the two adjacent battery cells 100 are made more flush; when the diaphragm tail portion 5 is set on the bonding surface, the indentations caused by the compression of the two adjacent battery cells 100 are avoided, and the material falling caused by uneven force on the electrode is prevented.

[0195] In some embodiments, two adjacent battery cells 100 are attached to each other, and the surfaces where the two adjacent battery cells 100 are attached to each other are the surfaces with the largest area of ​​the battery cells 100;

[0196] The separator tail portions 5 of two adjacent battery cells 100 are respectively arranged on opposite surfaces of the bonding surfaces.

[0197] In some embodiments, the value range of d2 satisfies:

[0198] 20μm≤d2≤200μm.

[0199] This embodiment controls the lower limit of the thickness of the insulating film 4 to ensure that the battery cell has suitable puncture resistance. At the same time, by controlling the upper limit of the thickness of the insulating film 4, it avoids the insulating film 4 being too thick to affect the heat dissipation effect of the middle area between two adjacent battery cells 100, and avoids the reduction of energy density caused by the insulating film 4 being too thick.

[0200] In order to further verify the relationship between the puncture resistance f1 of the diaphragm 3, the thickness d1 of the diaphragm 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, several groups of embodiments and comparative examples are used for verification.

[0201] The puncture resistance test method used in this embodiment refers to "GBT 37841-2019 Test method for puncture resistance of plastic films and sheets".

[0202] The battery performance detection method used in this embodiment mainly includes a lithium precipitation test method and a micro-short circuit test method. Among them, the specific experimental steps of the lithium precipitation test method are as follows:

[0203] 20 batteries were prepared for each experimental example and comparative example, respectively. The batteries were packaged and filled with liquid. The batteries were charged at room temperature (25°C) in a constant current (0.05C) mode. Charging was stopped when the voltage reached 3.65V. The batteries were left to stand for 1 hour and then discharged at a current of 1C. Discharging was stopped when the voltage reached 2.7V. The batteries were disassembled and analyzed, the negative electrode plates were unfolded, and the surface of the plates was observed to see if there were any black spots. If more than 90% of the 20 batteries had no black spots, they were qualified.

[0204] The specific experimental steps of the micro-short circuit test method are as follows:

[0205] 20 batteries were prepared for each group of experimental examples and comparative examples. When the batteries were put into the shell, 50um SUS particles were added between the shell and the battery cell. The batteries were packaged and filled with liquid. The batteries were charged at room temperature (25°C) in a constant current (0.05C) mode. Charging was stopped when the voltage reached 3.65V. The batteries were left to stand for 1 hour and then discharged at a current of 1C. The discharge was stopped when the voltage reached 2.7V.

[0206] The battery is clamped and vibrated at 15KN, cycled at room temperature for 500CLS, and self-discharged. Self-discharge test: Charge the battery to full capacity at 1 / 3C current, leave it at room temperature (25℃) for 7 days, then test the battery capacity and calculate the self-discharge rate of the battery. The self-discharge rate is not more than 10% and is qualified.

[0207] After actual testing, the present invention is further described with specific embodiments in conjunction with Table 1 below:

[0208] Table 1

[0209]

[0210] First, the value ranges of various parameters of the battery cell provided by the present invention are summarized:

[0211] 200gf≤f1≤800gf;

[0212] 4 microns ≤ d1 ≤ 25 microns;

[0213] 700gf≤f2≤2050gf;

[0214] 20 microns ≤ d2 ≤ 150 microns;

[0215] And the relationship between each parameter satisfies: 0.1≤(f2·d1) / (f1·d2)≤9.

[0216] 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.

[0217] Among them, the numerical value of the relationship (f2·d1) / (f1·d2) of Examples 1 to 17 satisfies 0.1≤(f2·d1) / (f1·d2)≤9. After the lithium plating experiment and the micro-short circuit experiment, more than 90% of the 20 batteries in each embodiment have no black spots, meeting the pass rate requirement of the lithium plating experiment; at the same time, the self-discharge rate of each embodiment is not more than 10%, meeting the pass rate requirement of the micro-short circuit experiment.

[0218] However, in Comparative Examples 1 to 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) cannot satisfy 0.1≤(f2·d1) / (f1·d2)≤9, wherein the value of (f2·d1) / (f1·d2) in Comparative Example 1 is greater than the upper limit, and after the lithium precipitation experiment and the micro-short circuit experiment, the proportion of the number of batteries without black spots in the 20 batteries in Comparative Example 1 is only 65%, which cannot meet the qualified rate requirements of the lithium precipitation experiment; the self-discharge rate of Comparative Example 1 is not greater than 10%, which meets the qualified rate requirements of the micro-short circuit experiment. Among them, the value of (f2·d1) / (f1·d2) in Comparative Example 2 is less than the lower limit, and after the lithium precipitation experiment and the micro-short circuit experiment, the 20 batteries in Comparative Example 2 meet the requirements of more than 90% without black spots, which meet the qualified rate requirements of the lithium precipitation experiment; but the self-discharge rate of Comparative Example 2 is 80%, which is greater than the 10% self-discharge qualified rate requirement.

[0219] It can be seen that, taking Comparative Examples 1 and 2 as examples, when 0.1≤(f2·d1) / (f1·d2)≤9 cannot be satisfied, the provided battery cannot meet the performance test requirements.

[0220] According to an embodiment of the present invention, in another aspect, a battery module is provided, comprising: the battery as described above.

[0221] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may 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 present invention.

Claims

1. A battery cell, characterized in that: include: A plurality of pole pieces (1); A diaphragm (3) is arranged between the positive and negative electrode sheets; The diaphragm (3) at least partially covers the outer surface of the battery core; An insulating film (4), the insulating film (4) at least partially covering the outer side 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 insulating film (4) is at least partially attached to the first region (1011) and extends to the second region (1012); along the length direction of the battery cell, the length b of the insulating film (4) covering the first region (1011) is, and the length a of the insulating film (4) covering the second region (1012) is, satisfying: 0.03≤a / b≤39; Along the thickness direction of the battery core, the number of layers of the separator (3) is n, and the thickness of the battery core is h, satisfying the following: 5%≤d1·n / h≤20%.

2. The battery cell according to claim 1, characterized in that: The value range of the puncture resistance f2 of the insulating film (4) is: 800gf≤f2≤2040gf.

3. The battery cell according to claim 1, characterized in that: The puncture resistance f1 of the diaphragm (3) has a value range of: 200gf≤f1≤800gf; The thickness d1 of the diaphragm (3) has a value range of: 4 micrometers ≤ d1 ≤ 25 micrometers; The value range of the thickness d2 of the insulating film (4) is: 20 micrometers ≤ d2 ≤ 150 micrometers.

4. The battery cell according to claim 1, characterized in that: The length a of the insulating film (4) covering the second region (1012) has a value range of 15 mm ≤ a ≤ 585 mm.

5. The battery cell according to claim 1, characterized in that: The circumference of the battery cell in a plane perpendicular to the height direction of the battery cell is c, satisfying: 0.03≤a / c≤0.

98.

6. The battery cell according to claim 1, 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 diaphragm (3) forms a diaphragm tail portion (5) on the large surface of the battery cell, and the edge of the diaphragm tail portion (5) is located at 1 / 3 to 2 / 3 of the large surface of the battery cell along the length direction of the battery cell.

7. The battery cell according to claim 1, 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 diaphragm (3) forms a diaphragm tail portion (5) on the large surface of the battery cell, and the edge of the diaphragm tail portion (5) exceeds the 1 / 2 position of the large surface of the battery cell along the length direction of the battery cell.

8. The battery cell according to claim 1, characterized in that: After covering the pole piece (1) located at the outermost layer of the battery core in the thickness direction, the diaphragm (3) continues to surround the circumference of the battery core and the number of wrapping turns is greater than or equal to one turn.

9. The battery cell according to claim 8, characterized in that: The diaphragm (3) continues to surround the circumference of the battery core and wraps the battery core for one to two turns, and satisfies: 8gf / μm≤f1 / d1≤200gf / μm.

10. The battery cell according to claim 8, characterized in that: The diaphragm (3) continues to surround the circumference of the battery core and wraps the battery core for more than two turns, and satisfies: 8gf / μm≤f1 / d1≤190gf / μm.

11. The battery cell according to claim 1, 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 diaphragm (3) forms a diaphragm tail portion (5) on the large surface of the battery cell. The diaphragm 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 diaphragm 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, satisfying the following: 0.25≤g / c≤0.

5.

12. The battery cell according to claim 1, characterized in that: Along the thickness direction of the battery cell, the thickness of the battery cell is h, which satisfies: h≥20 mm, and satisfies: 1≤(f2·d1) / (f1·d2)≤8.

13. The battery cell according to claim 1, characterized in that: The insulating film (4) comprises an insulating tape, and the material of the insulating tape comprises: PP or PET.

14. The battery cell according to claim 1, characterized in that: The insulating film (4) comprises a film body and an adhesive layer adhered to one side of the film body.

15. The battery cell according to claim 1, characterized in that: The insulating film (4) at least partially covers the outer surface with the largest area among the outer surfaces of the battery core (100).

16. A battery, characterized in that: Comprising at least two battery cells (100) as claimed in any one of claims 1 to 15.

17. The battery according to claim 16, characterized in that Two adjacent battery cells (100) are attached to each other, at least one layer of the insulating film (4) is provided between the two adjacent battery cells (100), and the following condition is satisfied: 0.1≤(f2·d1) / (f1·d2)≤7.

2.

18. The battery according to claim 16, characterized in that The battery further comprises a shell (2), the battery cell (100) is arranged in the shell (2), the insulating film (4) is arranged between at least one of the battery cells (100) and the shell (2), and the following condition is satisfied: 1≤(f2·d1) / (f1·d2)≤8.

5.

19. The battery according to claim 18, characterized in that The housing (2) comprises a steel shell and satisfies: 900gf≤f2≤2050gf.

20. The battery according to claim 18, characterized in that Two adjacent battery cells (100) are bonded to each other, and the separator tail portions (5) of the two adjacent battery cells (100) are respectively arranged on surfaces opposite to the bonding surfaces.

21. The battery according to claim 16, characterized in that The value range of d2 satisfies: 20μm≤d2≤200μm.

22. A battery module, characterized in that: Comprising a battery as claimed in any one of claims 16 to 21 above.

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