Insulating film and single cell

Abstract

This invention provides an insulating film and a single-cell battery. The insulating film is used to encapsulate a single-cell battery cell assembly. The insulating film includes multiple side-covering sheets and a first auxiliary bending portion disposed between two adjacent side-covering sheets. The side-covering sheets and the first auxiliary bending portion are alternately arranged, and an opening in the insulating film is formed at the same end along the height direction. The first auxiliary bending portion extends along the height direction, and the distance from the end of the first auxiliary bending portion near the opening of the insulating film to the opening is d. The thickness of the side-covering sheet is t, and d and t conform to the following formula: 0.6mm 2 ≤t×d≤1.125mm 2 The single-cell battery includes the insulating film. By setting the range of values ​​for the product of d and t, this invention can ensure the structural strength and tear resistance of this region, improve the reliability of the insulating film and the safety of the battery, while avoiding any impact on the battery density.

Description

Technical Field

[0001] This utility model relates to the field of batteries, and in particular to an insulating film and a single battery cell. Background Technology

[0002] Square batteries are a commonly used structure for lithium-ion power batteries. They consist of wound or stacked battery cells made from positive and negative electrodes and a separator, which are then assembled into a square casing before encapsulation. During the casing assembly process, because the casing is typically made of hard materials like aluminum or steel, its sharp edges and burrs pose a risk of scratching and damaging the battery cells. Therefore, before installing the battery cells into the casing, a soft and flexible insulating film (also called Mylar film) is used to cover the battery cells. This prevents direct contact between the battery cells and the outer aluminum casing, avoiding short circuits, aluminum corrosion, and damage to the battery cells caused by scratches from the aluminum casing.

[0003] Currently, with the increasing demands for battery capacity and the need for lower structural components, engineers have come up with the idea of ​​increasing the space reserved inside the casing for the battery cell assembly by thinning the insulation film. Utility Model Content

[0004] The technical problem to be solved by this utility model is to overcome the defect in the prior art where the thinning of the insulating film wall thickness leads to easy tearing of the insulating film edge area, resulting in a reduction in the insulating effect of the insulating film and affecting the safety of the battery. The present invention provides an insulating film and a single battery cell.

[0005] The present invention solves the above-mentioned technical problems through the following technical solution:

[0006] An insulating film for covering a single battery cell assembly is characterized in that the insulating film includes multiple side covering sheets and a first auxiliary bending portion disposed between two adjacent side covering sheets, the first auxiliary bending portion being used to assist bending at the connection between two adjacent side covering sheets; the side covering sheets and the first auxiliary bending portion are alternately arranged, and an opening in the insulating film is formed at the same end along the height direction of the insulating film;

[0007] The first auxiliary bending portion extends along the height direction, and the distance from the end of the first auxiliary bending portion near the opening of the insulating film to the opening of the insulating film is d. The thickness of the side covering sheet is t, and d and t conform to the following formula:

[0008] 0.6mm 2 ≤t×d≤1.125mm 2 .

[0009] Preferably, t is greater than or equal to 0.05 mm and less than or equal to 0.375 mm; and / or d is greater than or equal to 3 mm and less than or equal to 22.5 mm.

[0010] Preferably, 0.75mm 2 ≤t×d≤0.9mm 2 .

[0011] Preferably, t is greater than or equal to 0.08 mm and less than or equal to 0.15 mm; and / or d is greater than or equal to 9.3 mm and less than or equal to 15 mm.

[0012] Preferably, the first auxiliary bending portion includes a plurality of weak portions spaced apart along the height direction, and the distance from the weak portion closest to the opening of the insulating film to the opening of the insulating film among the plurality of weak portions is d.

[0013] Preferably, the insulating film further includes a bottom covering sheet, and a plurality of the side covering sheets are connected to one end of the bottom covering sheet in the height direction. The plurality of the side covering sheets include a first side covering area respectively disposed at both ends in the width direction of the bottom covering sheet, and a second side covering area respectively disposed at both ends in the length direction of the bottom covering sheet.

[0014] The first side covering area is connected to the adjacent second side covering area at both ends along the length direction, and the first auxiliary bending portion is disposed between the first side covering area and the adjacent second side covering area.

[0015] The insulating film further includes a thickening layer, the wall thickness of which is greater than the wall thickness of the side covering sheet;

[0016] The thickening layer is disposed on the end face of the side covering sheet on the side away from the bottom covering sheet in the height direction, and the thickening layer includes a first thickening layer unit and a second thickening layer unit. The first thickening layer unit is connected to the first side covering area, and the first thickening layer unit extends toward the second side covering area to form the second thickening layer unit. The second thickening layer unit is connected to the second side covering area.

[0017] Preferably, the insulating film satisfies one or more of the following conditions:

[0018] a1. Define the length of the thickened layer in the height direction as a, where 1.6mm ≤ a ≤ 10mm;

[0019] b2. Define the length of the first thickening layer unit in the length direction of the bottom covering sheet as b, where 5mm≤b≤20mm;

[0020] c3. Define the length of the second thickening layer unit in the width direction of the bottom covering sheet as c, where 5mm≤c≤20mm;

[0021] d4. The wall thickness of the thickened layer is greater than or equal to 0.1 mm;

[0022] e5. The wall thickness of the side covering sheet is 0.08–0.2 mm;

[0023] f6. The wall thickness of the thickened layer is less than or equal to 0.3 mm.

[0024] Preferably, the side covering sheet and the thickening layer are integrally formed.

[0025] Preferably, the side covering sheet has a body region and a thickened region, the body region extending outward toward the body region at one end away from the bottom covering sheet in the height direction to form the thickened region, and the thickened region folding toward the body region to form the thickened layer.

[0026] Preferably, the thickened layer includes a first portion and a second portion, the first portion being integrally formed with the side covering sheet, the second portion being independent of the side covering sheet, and the second portion covering the first portion.

[0027] Preferably, the insulating film satisfies one or more of the following conditions:

[0028] a2. The first auxiliary bending portion is disposed between the first thickening layer unit and the second thickening layer unit;

[0029] The wall thickness of the first auxiliary bending portion is less than the wall thickness of the first thickened layer unit or the second thickened layer unit; or, the connection portion between the first thickened layer unit and the second thickened layer unit is partially cut to form the first auxiliary bending portion;

[0030] b2. The end of the thickened layer away from the bottom covering sheet in the wall thickness direction is flush with the end of the side covering sheet away from the bottom covering sheet in the wall thickness direction.

[0031] Alternatively, the thickened layer extends beyond the end of the side cover sheet in the wall thickness direction of the bottom cover sheet, away from the bottom cover sheet.

[0032] A single-cell battery, characterized in that it comprises:

[0033] The housing has an internal cavity and an opening at the top communicating with the cavity;

[0034] A cover plate assembly is disposed over the opening, the cover plate assembly including a cover plate body and an insulating member, the insulating member being disposed on the side of the cover plate body facing the receiving cavity;

[0035] The battery cell assembly is housed within the receiving cavity;

[0036] Preferably, the insulating film covers the battery cell assembly.

[0037] Preferably, along the height direction, the insulating film has a connection area at one end near the opening of the insulating film, and the connection area is connected to the insulating element;

[0038] Along the circumferential direction of the opening in the insulating film, the distance between the end of the connecting area near the first auxiliary bending portion and the first auxiliary bending portion is e, where e ≥ 1 mm.

[0039] Ideally, 4mm ≥ e ≥ 3mm.

[0040] Preferably, the insulating film further includes a bottom covering sheet, and a plurality of the side covering sheets are connected to one end of the bottom covering sheet in the height direction. The plurality of the side covering sheets include a first side covering area respectively disposed at both ends in the width direction of the bottom covering sheet, and a second side covering area respectively disposed at both ends in the length direction of the bottom covering sheet.

[0041] The first side covering area is connected to the adjacent second side covering area at both ends along the length direction, and the first auxiliary bending portion is disposed between the first side covering area and the adjacent second side covering area.

[0042] The second side covering area includes two side covering units that partially overlap in the length direction. One end of each side covering unit is connected to the corresponding first side covering area in the width direction, and the other end partially overlaps in the length direction to form an overlapping area.

[0043] An adhesive layer is provided on the overlapping area, the adhesive layer is used to fix the two side covering units forming the overlapping area, and the adhesive layer is disposed near the bottom covering sheet.

[0044] Preferably, along the height direction, the adhesive layer includes a first side close to the bottom cover sheet and a second side away from the bottom cover sheet;

[0045] Along the height direction, the height of the cell assembly is h, and the distance from the second side to the bottom covering sheet is f, where f ≤ 5 / 9h.

[0046] Preferably, f ≤ 1 / 3h; and / or, 25mm ≤ f ≤ 35mm.

[0047] Preferably, along the height direction of the individual battery cell, the edge of the insulating member away from the cover plate body is the lower edge of the insulating member;

[0048] The insulating film also includes a bent region connecting two adjacent side covers along the circumferential direction, at least a portion of the outer surface of the bent region includes an arc surface, and the edge of the side cover near the cover body is the upper edge of the side cover.

[0049] The bending area includes a bending body and a tear-resistant portion connected to the bending body and disposed on one side near the cover plate body. The first auxiliary bending portion is disposed on the bending body. In the height direction, there is a height difference between the edge of the tear-resistant portion on the side near the cover plate body and the upper edge of the side covering sheet. The position of the tear-resistant portion furthest from the cover plate body is closer to the cover plate body than the lower edge of the insulating member.

[0050] Preferably, the tear-resistant portion is a protrusion extending from the bending body toward the cover body and protruding beyond the upper edge of the side cover sheet along the height direction, and / or, the tear-resistant portion is a groove recessed from the bending body toward the upper edge of the side cover sheet along the height direction.

[0051] Preferably, along the height direction, the position on the outer edge of the protrusion furthest from the cover plate body is the lowest position of the protrusion, and the position closest to the cover plate body is the highest position of the protrusion. The distance between the highest position and the lowest position of the protrusion is D, where 8mm ≥ D ≥ 1.6mm; or,

[0052] Along the height direction, the position on the inner wall of the groove furthest from the cover plate body is the lowest position of the groove, and the position closest to the cover plate body is the highest position of the groove. The distance between the highest position and the lowest position of the groove is D, where 8mm ≥ D ≥ 1.6mm.

[0053] The positive and progressive effects of this utility model are as follows:

[0054] This invention, by setting the range of the product of d and t, ensures the structural strength and tear resistance of the region, improving the reliability of the insulating film and the safety of the battery while avoiding any impact on battery density. This is because the distance d from the end of the first auxiliary bending portion near the opening of the insulating film to the opening (i.e., the spacing between the first auxiliary bending portion and the opening of the insulating film), multiplied by d and the thickness t of the side covering sheet, represents the cross-sectional area at that spacing. The size of this cross-sectional area determines the structural strength and tear resistance at that location. By limiting the range of the product of d and t to be greater than or equal to 0.6 mm... 2This ensures that the cross-sectional area can guarantee the structural strength and tear resistance of the region; the larger the range of values ​​for this cross-sectional area, the larger the space it occupies, thus affecting the battery density. Therefore, the product of d and t is limited to a value less than or equal to 1.125 mm. 2 This avoids affecting battery density. Moreover, as shown by the formula, when the thickness t of the side cladding decreases, the corresponding increase in distance d can ensure that the position corresponding to the cross-sectional area can achieve effective structural strength and tear resistance. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the structure of the insulating film covering state in Embodiment 1 of this utility model.

[0056] Figure 2 for Figure 1 A magnified structural diagram of part A in the middle.

[0057] Figure 3 This is a schematic diagram of the unfolded state of the insulating film in Embodiment 1 of this utility model.

[0058] Figure 4 for Figure 3 A magnified structural diagram of part B.

[0059] Figure 5 This is a three-dimensional structural diagram of a single battery cell according to Embodiment 1 of this utility model.

[0060] Figure 6 This is a partial three-dimensional structural diagram (I) of a single battery cell according to Embodiment 1 of this utility model.

[0061] Figure 7 for Figure 6 A magnified structural diagram of section C.

[0062] Figure 8 This is a partial three-dimensional structural diagram (II) of a single battery cell according to Embodiment 1 of this utility model.

[0063] Figure 9 for Figure 10 A magnified structural diagram of section E in the middle.

[0064] Figure 10 This is a partial side view of the single cell structure of Embodiment 1 of this utility model.

[0065] Figure 11 This is a three-dimensional structural diagram of the assembly of the insulating film and cover plate in Embodiment 2 of this utility model.

[0066] Figure 12 This is a schematic diagram of the unfolded state of the insulating film in Embodiment 2 of this utility model.

[0067] Figure 13 This is a partial structural diagram of a single battery cell according to Embodiment 2 of this utility model.

[0068] Figure 14 This is a schematic diagram of the unfolded structure of the insulating film in Embodiment 3 of this utility model.

[0069] Figure 15 This is a partial structural schematic diagram of a single battery cell in Embodiment 5 of this utility model.

[0070] Figure 16 This is a schematic diagram of the unfolded state of the insulating film in Embodiment 5 of this utility model.

[0071] Figure 17 for Figure 16 A magnified structural diagram of section F in the middle.

[0072] Figure 18 This is a partial structural schematic diagram of a single battery cell according to Embodiment 6 of this utility model.

[0073] Figure 19 This is a schematic diagram of the unfolded state of the insulating film in Embodiment 6 of this utility model.

[0074] Figure 20 for Figure 19 A magnified structural diagram of section G in the middle.

[0075] Explanation of reference numerals in the attached figures

[0076] 100 single cell; 1 casing; 2 cover plate assembly; 21 cover plate body; 22 insulating component; 3 terminal post; 4 cell assembly; 5 insulating film; 51 side cover sheet; 511 first side cover area; 512 second side cover area; 513 side cover unit; 514 body area; 515 overlapping area; 516 thickened area; 517 folded edge area; 52 insulating film opening; 53 first auxiliary bending part; 531 weak part; 54 bottom cover sheet; 56 thickened layer; 561 first thickened layer unit; 562 second thickened layer unit; 57 second auxiliary bending part; 58 bending area; 580 bending body; 581 protrusion; 5811 lowest position of protrusion; 5812 highest position of protrusion; 582 groove; 5821 lowest position of groove; 59 third auxiliary bending part; 60 connecting area; 70 adhesive layer; 71 first side; 72 second side. Detailed Implementation

[0077] The present invention will be described more clearly and completely below with reference to the accompanying drawings, using a preferred embodiment.

[0078] In the prior art, the wall thickness of the insulating film is usually around 0.15 mm. As the wall thickness of the insulating film is reduced to around 0.1 mm, stress concentration is more likely to occur in the bending area near the opening of the insulating film, which can lead to tearing of the insulating film. This damages the insulation barrier between the casing and the battery cell assembly, reduces the electrical clearance and creepage distance, and poses a safety risk.

[0079] Example 1

[0080] This embodiment provides an insulating film and a single battery cell, which is used to power electrical equipment such as electric vehicles.

[0081] like Figure 1 and Figure 2 As shown, the insulating film 5 is used to cover the cell assembly 4 of a single battery cell. The insulating film 5 includes multiple side covering sheets 51 and a first auxiliary bending portion 53 disposed between two adjacent side covering sheets 51. The first auxiliary bending portion 53 is used to assist the bending at the connection between two adjacent side covering sheets 51. The side covering sheets 51 and the first auxiliary bending portion 53 are alternately arranged, and an insulating film opening 52 is formed at the same end along the height direction H of the insulating film 5.

[0082] The first auxiliary bending portion 53 extends along the height direction H, and the distance from the end of the first auxiliary bending portion 53 near the opening 52 of the insulating film to the opening 52 of the insulating film is d. The thickness of the side covering sheet 51 is t, and d and t conform to the following formula:

[0083] 0.6mm 2 ≤t×d≤1.125mm 2 .

[0084] In this way, by setting the range of the product of d and t, the structural strength and tear resistance of this area can be ensured, improving the reliability of the insulating film 5 and the safety of the battery while avoiding any impact on the battery density. This is because the distance d from the end of the first auxiliary bending portion 53 near the opening 52 of the insulating film to the opening 52, i.e., the spacing between the first auxiliary bending portion 53 and the opening 52 of the insulating film, is the cross-sectional area at that spacing position when multiplied by d and the thickness t of the side covering sheet 51. The size of the cross-sectional area determines the structural strength and tear resistance at that position. By limiting the range of the product of d and t to be greater than or equal to 0.6 mm... 2 This ensures that the cross-sectional area can guarantee the structural strength and tear resistance of the region; the larger the range of values ​​for this cross-sectional area, the larger the space it occupies, thus affecting the battery density. Therefore, the product of d and t is limited to a value less than or equal to 1.125 mm. 2This avoids affecting battery density. Moreover, as shown by the formula, when the thickness t of the side covering 51 decreases, the distance d is increased accordingly, ensuring that the position corresponding to the cross-sectional area can achieve effective structural strength and tear resistance.

[0085] It should be noted that the insulating film 5 is bent at the first auxiliary bending part 53 to form a corner edge in order to cover the battery cell assembly 4.

[0086] Furthermore, t is greater than or equal to 0.05 mm and less than or equal to 0.375 mm; d is greater than or equal to 3 mm and less than or equal to 22.5 mm. By limiting the range of the thickness t of the side covering sheet 51, on the one hand, the thickness t is avoided from being too large, which would affect the battery density; on the other hand, the thickness t is avoided from being too small, which would weaken the structural strength of the side covering sheet 51. By limiting the range of the distance d, on the one hand, the distance d is avoided from being too large, which would affect the auxiliary bending function of the first auxiliary bending portion 53; on the other hand, the distance d is avoided from being too small, which would fail to improve the structural strength and tear resistance.

[0087] Furthermore, 0.75mm 2 ≤t×d≤0.9mm 2 By further limiting the range of values ​​for the product of d and t, the structural strength and tear resistance of this region can be further ensured while avoiding any impact on battery density.

[0088] Furthermore, t is greater than or equal to 0.08 mm and less than or equal to 0.15 mm; d is greater than or equal to 9.3 mm and less than or equal to 15 mm. By further limiting the range of the thickness t, the structural strength and tear resistance of this area can be better ensured while avoiding impact on the battery density. By further limiting the range of the distance d, the structural strength and tear resistance of this area can be better ensured while avoiding impact on the auxiliary bending function of the first auxiliary bending portion 53.

[0089] Furthermore, in this embodiment, the first auxiliary bending portion 53 includes a plurality of weak portions 531 spaced apart along the height direction H. The distance from the weak portion 531 closest to the insulating film opening 52 to the insulating film opening 52 is d.

[0090] The thickness of the weak portion 531 is less than the thickness of other areas of the side covering sheet 51. The weak portion 531 can be formed by rolling on the insulating film 5 using a structure such as gears, thereby making it easier to bend the connection between the two side covering sheets 51 at the location of the weak portion 531. However, it is not limited to this. In other embodiments, the weak portion 531 is a hollow structure (cutout). The shape of the weak portion 531 is a strip, and the length direction of the strip is in the same direction as the height direction H.

[0091] However, this is not the only possibility. In other embodiments, the first auxiliary bending portion 53 may also be a continuous structure. The thickness of this continuous structure is less than the thickness of other areas of the side covering sheet 51.

[0092] It should be noted that the insulating film 5 is not only applicable to the cell assembly 4 that covers the top-terminal single cell, but also applicable to the cell assembly 4 that covers the two-terminal single cell.

[0093] In this embodiment, the insulating film 5 covers the cell assembly 4 of the top-electrode type single battery cell. The insulating film 5 also includes a bottom covering sheet 54, and multiple side covering sheets 51 are connected to one end of the bottom covering sheet 54 in the height direction H (i.e., the wall thickness direction of the bottom covering sheet 54). The multiple side covering sheets 51 include first side covering areas 511 respectively disposed at both ends in the width direction W of the bottom covering sheet 54, and second side covering areas 512 respectively disposed at both ends in the length direction L of the bottom covering sheet 54.

[0094] The first side covering area 511 is connected to the adjacent second side covering area 512 at both ends along the length direction L. The first auxiliary bending part 53 is disposed between the first side covering area 511 and the adjacent second side covering area 512. By setting the specific position of the first auxiliary bending part 53, the bending between the first side covering area 511 and the adjacent second side covering area 512 is realized.

[0095] The second side covering area 512 includes two side covering units 513 that partially overlap in the length direction L. One end of the two side covering units 513 along the width direction W is connected to the corresponding first side covering area 511, and the other end partially overlaps in the length direction L to form an overlapping area 515.

[0096] like Figure 3 and Figure 4 As shown, when the insulating film 5 is in the unfolded state, the bottom covering sheet 54 has a first side covering area 511 and two side covering units 513 at both ends along the width direction W, and the two side covering units 513 are located at both ends of the first side covering area 511 along the length direction L. Figure 1 and Figure 2 As shown, after the insulating film 5 is folded, two side covering units 513 located on the same side and connected to different first side covering areas 511 overlap and are fixed to form a second side covering area 512.

[0097] Furthermore, a second auxiliary bending portion 57 is provided between the first side covering area 511 and the bottom covering sheet 54. The second auxiliary bending portion 57 is used to assist the bending at the connection between the first side covering area 511 and the bottom covering sheet 54. By providing the second auxiliary bending portion 57, the bending between the first side covering area 511 and the bottom covering sheet 54 is achieved. The specific structure of the second auxiliary bending portion 57 is the same as the specific structure of the first auxiliary bending portion 53.

[0098] In other embodiments, the insulating film can also cover the cell assembly of a single-cell battery with terminals at both ends. In this insulating film, along the height direction of the insulating film, the two ends of multiple side covering sheets are surrounded by insulating film openings. That is, along the height direction, the two ends of the first auxiliary bending portion along the height direction are provided with insulating film openings, and the distance d between the two ends of the first auxiliary bending portion along the height direction and their adjacent insulating film openings is respectively.

[0099] Additionally, it should be noted that the aforementioned structure of the insulating film 5 refers to the structure after the insulating film 5 covers the electrode assembly of the single cell 100. In this case, the insulating film 5 is in a covered state. Please refer to [the relevant documentation]. Figure 1 and Figure 2 And in Figure 3 and Figure 4 The image shows the structure before the insulating film 5 covers the electrode assembly of the single cell 100. At this time, the insulating film 5 is in the unfolded state.

[0100] like Figures 5 to 7 As shown, the single-cell battery 100 of this embodiment includes: a casing 1, a cover plate assembly 2, terminals 3, a cell assembly 4, and an insulating film 5 as described above. This embodiment uses a top-terminal type single-cell battery as an example; in other alternative embodiments, the cell can also be of other forms, such as a two-terminal type. The height direction H of the insulating film is the same as the height direction of the single-cell battery 100 and the cell assembly 4. The circumferential direction of the opening 52 of the insulating film is the same as the peripheral direction of the side surface of the cell assembly 4.

[0101] The housing 1 has an internal cavity (not shown in the figure) and an opening at the top communicating with the cavity. A cover assembly 2 covers the opening and completely seals the opening at the top of the housing 1, ensuring that the internal cavity of the housing 1 remains closed after the battery cell assembly 4 is inserted into the housing. The cover assembly 2 includes a cover body 21 and an insulating member 22, with the insulating member 22 covering the side of the cover body 21 facing the cavity. The battery cell assembly 4 is housed within the cavity. A terminal post 3 is disposed on the cover plate and is electrically connected to the battery cell assembly 4 to enable current transmission.

[0102] The insulating film 5 is used to cover the outer surface of the battery cell assembly 4 before it is installed into the housing 1. After the covering is completed, the battery cell assembly 4 and the insulating film 5 are installed together into the receiving cavity inside the housing 1. The insulating film 5 plays a protective role for the battery cell assembly 4, preventing the housing 1 from causing scratches or other damage to the battery cell assembly 4 during the process of the battery cell assembly 4 being installed into the housing, avoiding damage to the battery cell assembly 4 during the assembly process, achieving insulation isolation between the battery cell assembly 4 and the housing 1, and preventing short circuits, corrosion and mechanical damage.

[0103] like Figures 8 to 10 As shown, along the height direction H, the insulating film 5 has a connecting region 60 at one end near the opening 52, and the connecting region 60 is connected to the insulating component 22. The connecting region 52 refers to the area where the insulating film 5 can be connected to the insulating component 22. This area is formed by heat melting or by coating an adhesive layer, etc., so that the area can be fixedly connected to the insulating component 22. By providing the connecting region 60, the fixed connection between the insulating film 5 and the insulating component 22 is achieved.

[0104] Furthermore, along the circumference of the opening 52 of the insulating film, the distance between the end of the connecting area 60 near the first auxiliary bending portion 53 and the first auxiliary bending portion 53 is e, where e ≥ 1 mm. Since the connection between the insulating film 5 and the insulating component 22 is usually fixed by heat fusion, by limiting the value of the distance e between the end of the connecting area 60 near the first auxiliary bending portion 53 and the first auxiliary bending portion 53 to be greater than or equal to 1 mm, it is possible to avoid the heat from heat fusion spreading to the corner edge and causing the material around the heat fusion mark to harden, thereby affecting the strength at the corner edge.

[0105] Furthermore, e≥2mm, so as to further limit the range of the distance e between the end of the connection area 60 near the first auxiliary bending part 53 and the first auxiliary bending part 53, thereby further avoiding the heat during hot melting from affecting the strength at the corner edge where the first auxiliary bending part 53 is located.

[0106] Furthermore, 4mm ≥ e ≥ 3mm. By further limiting the range of the distance e between the end of the connecting area 60 closest to the first auxiliary bending part 53 and the first auxiliary bending part 53, on the one hand, it avoids the distance e being too small, which would not effectively prevent the heat during hot melting from affecting the strength at the corner edge where the first auxiliary bending part 53 is located; on the other hand, it avoids the distance e being too large, which would make the distance between the connecting area 60 and the corner edge too large, thus failing to achieve an effective connection.

[0107] Furthermore, there are multiple connecting regions 60, which are spaced apart circumferentially along the opening 52 of the insulating film. By providing multiple connecting regions 60, more connection points can be provided, making the connection between the insulating film 5 and the insulating member 22 more robust. Furthermore, by spaced apart circumferentially along the insulating member 22, the stress points can be distributed, thereby improving the overall tensile strength. When there are multiple connecting regions 60, the distance e between the end of the connecting region 60 closest to the first auxiliary bending portion 53 and the first auxiliary bending portion 53 is e.

[0108] As previously described, the insulating film 5 also includes a bottom covering sheet 54, and multiple side covering sheets 51 are connected to one end of the bottom covering sheet 54 in the height direction H (i.e., the wall thickness direction of the bottom covering sheet 54). Each side covering sheet 51 includes a first side covering region 511 located at both ends in the width direction W of the bottom covering sheet 54, and a second side covering region 512 located at both ends in the length direction L of the bottom covering sheet 54. The first side covering region 511 is connected to its adjacent second side covering region 512 at both ends along the length direction L. A first auxiliary bending portion 53 is disposed between the first side covering region 511 and its adjacent second side covering region 512. Furthermore, a second auxiliary bending portion 57 is provided between the first side covering region 511 and the bottom covering sheet 54.

[0109] Further, the second side-covering area 512 includes two side-covering units 513 that partially overlap in the length direction L. One end of each side-covering unit 513 in the width direction is connected to the corresponding first side-covering area 511, and the other ends partially overlap in the length direction to form an overlapping area 515. An adhesive layer 70 is provided on the overlapping area 515 to fix the two side-covering units 513 forming the overlapping area 515. The adhesive layer 70 is disposed near the bottom covering sheet 54. In this embodiment, the adhesive layer 70 is an adhesive tape, but it is not limited to this. In other embodiments, the adhesive layer 70 may also be a coating structure.

[0110] Furthermore, along the height direction H, the adhesive layer 70 includes a first side 71 near the bottom cover sheet 54 and a second side 72 away from the bottom cover sheet 54.

[0111] Along the height direction H, the height of the cell assembly 4 is h, and the distance from the second side 72 to the bottom cover sheet 54 is f, where f ≤ 5 / 9h. That is, the distance f from the second side 72 to the bottom cover sheet 54 is less than or equal to 5 / 9 of the height h of the cell assembly 4. By controlling the value range of the distance f from the second side 72 of the adhesive layer 70 to the bottom cover sheet 54 to be less than or equal to 5 / 9h, the position of the fixing point of the adhesive layer 70 at the height of the cell assembly 4 is controlled. Since the expansion of the bare cell mainly occurs in the middle region, when fixing the insulating film 5, at least part of it near the middle is not fixed. This leaves space for the expansion of the bare cell and avoids the position of the insulating film 5 corresponding to the expansion position pulling on the corner edge of the insulating film 5 when the bare cell expands. In addition, the value range of the distance f must also take into account that when the insulating film 5 is thinned, in order to maintain the structural strength of the insulating film 5, the position of the fixing point of the adhesive layer 70 at the height of the cell assembly 4 must be appropriately maintained.

[0112] Furthermore, f ≤ 1 / 3h, that is, the distance f from the second side 72 to the bottom cover sheet 54 is less than or equal to 1 / 3 of the height h of the cell assembly 4. By further limiting the value range of the distance f to less than or equal to 1 / 3h, sufficient space is left for the expansion of the bare cell, thereby further avoiding the pulling of the corner edge of the insulating film 5 by the position corresponding to the expansion position when the bare cell expands.

[0113] Furthermore, 25mm≤f≤35mm. By limiting the range of the distance f, on the one hand, it avoids the distance f being too small, so as not to effectively connect the two second side covering areas 512; on the other hand, it avoids the distance f being too large, so as not to leave enough space for the expansion of the bare cell, and effectively avoid the position of the insulating film 5 corresponding to the expansion position pulling on the corner edge of the insulating film 5.

[0114] Furthermore, the first side 71 is closely attached to the bottom covering sheet 54 so that the adhesive layer 70 maximally connects the two second side covering areas 512 in the height direction H.

[0115] In this embodiment, by setting the range of the product of the distance d from the end of the first auxiliary bending portion 53 near the opening 52 of the insulating film to the opening 52 of the insulating film and the thickness t of the side covering sheet 51, the structural strength and tear resistance of this area can be ensured, the reliability of the insulating film 5 and the safety of the battery can be improved, and the impact on the battery density can be avoided.

[0116] Example 2

[0117] like Figure 11 and Figure 12As shown, the overall structure of the insulating film and single cell in this embodiment is basically the same as that in embodiment 1. The difference is that the insulating film 5 in this embodiment also includes a thickening layer 56. When the insulating film 5 is in a folded state, the thickening layer 56 is disposed on the side cover 51 on the end face away from the bottom cover 54 (the end face near the opening 52 of the insulating film) in the wall thickness direction (height direction H) of the bottom cover 54. The wall thickness of the thickening layer 56 is greater than the wall thickness of the side cover 51.

[0118] like Figure 11 As shown, in this embodiment, when the insulating film 5 is in a folded state, the end of the thickened layer 56 away from the bottom cover sheet 54 in the wall thickness direction is flush with the end of the side cover sheet 51 away from the bottom cover sheet 54 in the wall thickness direction.

[0119] Specifically, such as Figure 12 As shown, a notch is provided at the end of the connection between the first side covering area 511 and the side covering unit 513, away from the bottom covering piece 54. The notch extends through the side covering piece 51 in the wall thickness direction of the first side covering area 511 and the side covering unit 513. A thickening layer 56 is partially disposed within the notch. The outer contour of the thickening layer 56 matches the shape of the notch. The peripheral side surface of the thickening layer 56 is tightly fitted with the inner wall surface of the notch. The thickening layer 56 extends to the outer edge of the first side covering area 511 and the side covering unit 513 at the end away from the bottom covering piece 54 in the width direction.

[0120] A folded edge region 517 of the side covering sheet 51 is formed at the junction of the first side covering region 511 and the second side covering region 512. In this embodiment, the thickening layer 56 is provided only at the location of the folded edge region 517. In other alternative embodiments, a thickening layer 56 may be provided around one end of the opening 52 of the insulating film.

[0121] In other alternative embodiments, the thickening layer 56 and the side covering sheet 51 may be flush with the end of the bottom covering sheet 54 away from the bottom covering sheet 54 in the wall thickness direction (i.e., the end near the opening 52 of the insulating film in the height direction H), and the end of the thickening layer 56 away from the bottom covering sheet 54 in the wall thickness direction may extend beyond the end of the side covering sheet 51 away from the bottom covering sheet 54 in the wall thickness direction.

[0122] In this embodiment, the entire insulating film 5 is integrally formed, namely, the bottom covering sheet 54, the side covering sheet 51, and the thickening layer 56 are integrally formed. During the manufacturing process of the insulating film 5, the thickness of the insulating material is directly increased in the area of ​​the thickening layer 56. The integral forming process is simple, avoids the risk of interface peeling caused by multi-layer structure splicing, improves the stability and consistency of the overall structure, and reduces production costs.

[0123] In other alternative embodiments, the side covering sheet 51 and the thickening layer 56 may also be formed by splicing two independently molded structures.

[0124] Furthermore, such as Figure 11 and Figure 12 As shown, the thickening layer 56 includes a first thickening layer unit 561 and a second thickening layer unit 562. The first thickening layer unit 561 is connected to the first side covering area 511, and the first thickening layer unit 561 extends toward the second side covering area 512 to form the second thickening layer unit 562. The second thickening layer unit 562 is connected to the second side covering area 512. That is, in this embodiment, the first thickening layer unit 561 and the second thickening layer unit 562 in a single thickening layer 56 are continuous to completely cover the folded edge area 517 of the side covering sheet 51.

[0125] In this embodiment, by providing a thickening layer 56 in the easily torn folded edge area 517 of the side cover sheet 51, the overall wall thickness of the insulating film 5 in this area is increased, thereby effectively enhancing the structural strength and tear resistance of this area. This solves the stress concentration and tearing problems caused by the thinning of the wall thickness of the side cover sheet 51, thereby improving the reliability of the insulating film 5 and the safety of the battery.

[0126] Furthermore, such as Figure 11 and Figure 12 As shown, in this embodiment, the side covering sheet 51 has four folded edge areas 517, and each folded edge area 517 is provided with a thickening layer 56 to ensure that all four folded edge areas 517 can be effectively protected.

[0127] Furthermore, the shape of the thickened layer 56 is not specifically limited and can be rectangular, semi-circular, etc.

[0128] In this embodiment, the wall thickness of the side covering sheet 51 is the same everywhere, at 0.1 mm, and the wall thickness of the thickening layer 56 is the same everywhere, at 0.2 mm. By reasonably setting the wall thickness range of the side covering sheet 51 and the thickening layer 56, this embodiment can still provide sufficient structural support in key areas while ensuring that the overall wall thickness of the insulating film 5 is reduced. This balances space utilization and structural strength, and avoids excessive occupation of the storage space of the cell assembly 4 due to excessive thickening, thereby ensuring the power of the individual battery.

[0129] In other alternative embodiments, the wall thickness of the thickening layer 56 is greater than or equal to 0.1 mm to ensure that the thickening layer 56 has sufficient mechanical strength to withstand the stress during bending and assembly, avoiding the inability to provide effective reinforcement due to excessively thin walls, thereby further improving the tear resistance of the insulating film 5. Preferably, the wall thickness of the side covering sheet 51 is 0.08–0.2 mm, and the wall thickness of the thickening layer 56 is 0.1–0.3 mm.

[0130] like Figures 11-12 As shown, when the insulating film 5 is in a folded state, the length of the thickening layer 56 in the wall thickness direction (height direction H) of the bottom covering sheet 54 is defined as a, the length of the first thickening layer unit 561 in the length direction L of the bottom covering sheet 54 is b, and the length of the second thickening layer unit 562 in the width direction W of the bottom covering sheet 54 is c, where 1.6mm≤a≤10mm, 5mm≤b≤20mm, and 5mm≤c≤20mm. This embodiment, by limiting the size of the thickening layer 56, ensures that the area covered by the thickening layer 56 is sufficient to disperse stress and prevent tearing, while also saving the total amount of insulating film 5 and reducing costs.

[0131] In other alternative implementations, the dimensions of the thickened layer 56 can be designed to other values ​​according to actual needs.

[0132] like Figure 11 , Figure 12 and Figure 13 As shown, the side covering sheet 51 is bent to form a first side covering area 511 and a second side covering area 512. To facilitate bending of the side covering sheet 51, a first auxiliary bending portion 53 extending along the wall thickness direction (height direction H) of the bottom covering sheet 54 is provided between the first side covering area 511 and the second side covering area 512. Furthermore, since a single thickening layer 56 also covers the folded edge area 517, the thickening layer 56 also needs to be bent. Therefore, to facilitate bending of the thickening layer 56, a third auxiliary bending portion 59 extending along the wall thickness direction of the bottom covering sheet 54 is provided between the first thickening layer unit 561 and the second thickening layer unit 562 of a single thickening layer 56. The third auxiliary bending portion 59 corresponds to the first auxiliary bending portion 53 in position, that is, the two correspond in position in the length and width directions of the bottom covering sheet 54.

[0133] Specifically, in this embodiment, the first auxiliary bending portion 53 and the third auxiliary bending portion 59 are both sawtooth structures extending along the wall thickness direction of the bottom covering sheet 54. The sawtooth structure can be formed by rolling a structure such as gears on the insulating film 5. During the rolling process, the structure such as gears cuts the connecting portion of the first thickening layer unit 561 and the second thickening layer unit 562 as well as the thickening layer 56 to form the first auxiliary bending portion 53 and the third auxiliary bending portion 59, respectively.

[0134] In other alternative embodiments, the first auxiliary bending portion 53 and the third auxiliary bending portion 59 may also adopt other structures that can play an auxiliary bending role, such as a groove extending along the wall thickness direction of the bottom covering sheet 54. In this state, the wall thickness of the first auxiliary bending portion 53 is less than the wall thickness of the first thickening layer unit 561 or the second thickening layer unit 562, and the wall thickness of the third auxiliary bending portion 59 is less than the wall thickness of the thickening layer 56.

[0135] Example 3

[0136] like Figure 14 As shown, the overall structure of the insulating film and single cell in this embodiment is basically the same as that in embodiment 2. The difference is that the side covering sheet 51 and the thickening layer 56 in this embodiment are integrally formed. The integral forming process is simple, avoids the risk of interface peeling caused by the splicing of multi-layer structures, improves the stability and consistency of the overall structure, and reduces the production cost.

[0137] like Figure 14 As shown, the side covering sheet 51 has a body region 514 and a thickened region 516. When the insulating film 5 is in the unfolded state, the body region 514 extends outward from the end away from the bottom covering sheet 54 in the width direction to form the thickened region 516 (when the insulating film 5 is in the folded state, the body region 514 extends outward from the end away from the bottom covering sheet 54 in the wall thickness direction to form the thickened region 516). The thickened region 516 is bendable relative to the body region 514, and folds over the body region 514 in the direction towards the body region 514 to cover the body region 514, thereby forming a thickened layer 56. This molding method does not require changing the thickness of a portion of the insulating film, and the molding method is simple. The folding and covering method facilitates the positioning between the body region 514 and the thickened region 516, improving assembly efficiency.

[0138] Furthermore, when the insulating film 5 is in a folded state, the thickened region 516 is located between the body region 514 and the housing 1, that is, the thickened region 516 is folded outward toward the space accommodating the cell assembly 4 to prevent interference with the cell assembly 4. In other alternative embodiments, the thickened region 516 may also be folded inward toward the space accommodating the cell assembly 4.

[0139] Furthermore, after the insulating film 5 is folded, a connecting layer is provided at the end of the thickened area 516 facing the body area 514. The body area 514 and the thickened area 516 are bonded together through the connecting layer to fix their positions. In this embodiment, by providing a connecting layer, a firm connection between the body area 514 and the thickened area 516 is ensured, preventing peeling or displacement during bending or assembly, thereby further enhancing structural stability and insulation reliability.

[0140] In this embodiment, the connecting layer is fixed on the thickened area 516. In other alternative embodiments, the connecting layer can also be fixed on the body area 514, ensuring that the connecting layer is positioned between the body area 514 and the thickened area 516. This embodiment fixes the connecting layer on the thickened area 516 to omit the positioning process of the connecting layer on the body area 514, thereby improving assembly efficiency.

[0141] In other alternative implementations, the body region 514 and the thickened region 516 can also be fixed in other ways, such as local heat fusion.

[0142] In this embodiment, after the positions of the body region 514 and the thickened region 516 are fixed, the first auxiliary bending portion 53 and the third auxiliary bending portion 59 are uniformly processed on the insulating film 5, so that the third auxiliary bending portion 59 with corresponding positions is formed on both the body region 514 and the thickened region 516.

[0143] In other alternative embodiments, the first auxiliary bending portion 53 and the third auxiliary bending portion 59 may be processed first, and then the thickened area 516 may be folded over to fix the positions of the main body area 514 and the thickened area 516.

[0144] Example 4

[0145] The overall structure of the insulating film and single cell in this embodiment is basically the same as that in Embodiment 3. The difference is that in this embodiment, the thickening layer includes a first part and a second part. The first part is integrally formed with the side covering sheet, while the second part is independent of the side covering sheet and covers the first part. That is, the first part and the second part are independently formed components, which allows for flexible adjustment of the material and thickness of the thickening layer according to actual needs. This makes it suitable for different battery structures and assembly processes, improving the flexibility and adaptability of the design.

[0146] After the insulating film is folded, a connecting layer is provided at the end of the second part facing the first part, and the first part and the second part are bonded together through the connecting layer. This embodiment ensures a strong connection between the first and second parts by providing the connecting layer, preventing peeling or displacement during bending or assembly, and further enhancing structural stability and insulation reliability.

[0147] In this embodiment, the connecting layer is fixed to the second part. In other alternative embodiments, the connecting layer can also be fixed to the first part, ensuring that the connecting layer is positioned between the first and second parts. This embodiment fixes the connecting layer to the second part to omit the positioning process of the connecting layer on the first part, thereby improving assembly efficiency.

[0148] In other alternative implementations, the thickened area and the thickened layer can also be connected in other ways, such as localized heat fusion.

[0149] In this embodiment, after the positions of the first part and the second part are fixed, the first auxiliary bending part and the third auxiliary bending part are uniformly processed on the insulating film to form the third auxiliary bending part with corresponding positions on both the first part and the second part.

[0150] In other alternative implementations, the first auxiliary bending portion and the third auxiliary bending portion can be processed first, and then the second portion can be bonded together to fix the positions of the first portion and the second portion.

[0151] Example 5

[0152] like Figures 15 to 17 As shown, the overall structure of the insulating film and single cell in this embodiment is basically the same as that in Embodiment 1. The difference is that the insulating film 5 also includes a bent region 58 that connects two adjacent side coverings 51 along the circumferential direction of the opening 52 of the insulating film. At least a portion of the outer surface of the bent region 58 includes an arc surface, and the edge of the side covering 51 near the cover plate body 21 is the upper edge 510 of the side covering. The circumferential direction of the side of the cell assembly 4 is in the same direction as the circumferential direction of the opening 52 of the insulating film.

[0153] The bending region 58 includes a bending body 580 and a tear-resistant portion connected to the bending body 580 and disposed on the side near the cover plate body 21. In the height direction H, there is a height difference between the edge of the tear-resistant portion on the side near the cover plate body 21 and the upper edge 510 of the side covering sheet, and the position of the tear-resistant portion furthest from the cover plate body 21 is closer to the cover plate body 21 than the lower edge 221 of the insulating member. Along the height direction H of the single cell 100, the edge of the insulating member 22 furthest from the cover plate body 21 is the lower edge 221 of the insulating member.

[0154] In this way, by providing an anti-tear portion on the side of the bent body 580 near the cover body 21, there is a height difference between the edge of the anti-tear portion near the cover body 21 and the upper edge 510 of the side covering sheet. Through the height difference, the stress on both sides of the side covering sheet 51 can be buffered when the anti-tear portion is pulled, so that the edge of the anti-tear portion near the cover body 21 is not easily torn, thereby affecting the insulation effect at the location of the anti-tear portion. Moreover, the position of the anti-tear portion furthest from the cover body 21 is closer to the cover body 21 than the lower edge 221 of the insulating component, so that the anti-tear portion can extend beyond the edge of the bare cell (cell assembly 4), thereby further ensuring the isolation of the bare cell and the shell by the anti-tear portion and the overall insulating film 5, improving the overall insulation effect of the insulating film, and thus improving the reliability of the insulating film 5 and the safety of the battery.

[0155] In this embodiment, the tear-resistant part is a protrusion 581 that protrudes from the bending body 580 toward the cover plate body 21 along the height direction H and extends out of the upper edge 510 of the side covering sheet.

[0156] Along the height direction H, the position furthest from the cover plate body 21 on the outer edge of the protrusion 581 is the lowest position 5811 of the protrusion, which is closer to the cover plate body 21 than the lower edge 221 of the insulating part.

[0157] In this way, by setting the tear-resistant portion as a protrusion 581 extending from the bending body 580 toward the cover plate body 21 along the height direction H and protruding from the upper edge 510 of the side covering sheet, the solid area of ​​the bending region 58 is increased. The height difference between the outer edge of the protrusion 581 and the upper edge 510 of the side covering sheet provides a buffer for the stress on both sides of the side covering sheet 51 when it is pulled, making the edge of the tear-resistant portion near the cover plate body 21 less likely to be torn, thus affecting the insulation effect at the tear-resistant portion location. Furthermore, by setting the lowest position 5811 of the protrusion to be closer to the cover plate body 21 than the lower edge 221 of the insulating component, the entire structure of the protrusion 581 can extend beyond the edge of the bare cell, thereby further ensuring the isolation of the bare cell and the casing by the protrusion 581 and the overall insulating film 5, improving the overall insulation effect of the insulating film, and thus improving the reliability of the insulating film 5 and the safety of the battery. It should be noted that the edge of the tear-resistant part near the cover plate body 21, in the structure where the tear-resistant part is a protrusion 581, is the edge of the protrusion 581 near the cover plate body 21. The position of the tear-resistant part furthest from the cover plate body 21, in the structure where the tear-resistant part is a protrusion 581, is the position on the outer edge of the protrusion 581 furthest from the cover plate body 21 (the lowest position 5811 of the protrusion), that is, the connection position between the protrusion 581 and the side covering piece 51. The protrusion 581 protrudes from the bent body 580 toward the cover plate body 21 beyond the upper edge 510 of the side covering piece, that is, the protrusion 581 protrudes from the bent body 580 toward the direction close to the cover plate body 21 beyond the upper edge 510 of the side covering piece.

[0158] Furthermore, along the height direction H, the edge of the cover body 21 near the insulating member 22 is the lower edge 211 of the cover body; along the height direction H, the position on the outer edge of the protrusion 581 closest to the cover body 21 is the highest position 5812 of the protrusion, and there is a gap between the highest position 5812 of the protrusion and the lower edge 211 of the cover body to avoid the protrusion 581 interfering with the cover body 21, thereby affecting the complete sealing of the opening at the top of the housing 1 by the cover assembly 2.

[0159] Along the height direction H, there is a gap between the upper edge 510 of the side cover and the lower edge 211 of the cover body to avoid the upper edge 510 of the side cover interfering with the cover body 21, thereby affecting the complete sealing of the opening at the top of the housing 1 by the cover assembly 2.

[0160] Furthermore, along the height direction H, the distance from the highest point 5812 of the protrusion to the lowest point 5811 of the protrusion is D, where D ≥ 1.6 mm. This distance D, representing the height of the protrusion 581 along the height direction H, is defined as greater than or equal to 1.6 mm to ensure that the protrusion 581 has an effective height, thereby increasing the solid area of ​​the bending region 58 and ensuring the structural strength and tear resistance of this region.

[0161] Furthermore, 8mm ≥ D ≥ 1.6mm. By limiting the specific range of this distance D, on the one hand, by ensuring that the protrusion 581 has an effective height, the solid area of ​​the bending area 58 is increased, thereby ensuring the structural strength and tear resistance of the area; on the other hand, the height of the protrusion 581 is avoided from being too high, which would interfere with the cover plate body 21 and thus affect the complete sealing of the opening at the top of the shell 1.

[0162] Furthermore, the outer edge of the protrusion 581 includes at least a partial arc shape, that is, at least part of the outer edge of the protrusion 581 is an arc-shaped structure. The arc-shaped structure enables the outer edge of the protrusion 581 to better distribute stress and makes the outer edge of the protrusion 581 transition smoothly, reducing the difficulty of component docking.

[0163] The protrusion 581 may be arc-shaped, rectangular, or polygonal. The arc shape includes circular arcs, elliptical arcs, or irregular arcs. Preferably, the protrusion 581 is circular arc-shaped.

[0164] Furthermore, the two ends of the protrusion 581 along the circumferential direction are respectively located on the two adjacent side coverings 51, so as to make the structure of the protrusion 581 more balanced.

[0165] Furthermore, the connection between the protrusion 581 and the upper edge 510 of the side covering sheet is a rounded corner structure, so that the connection can better distribute stress and make the connection smooth transition, reducing the difficulty of component docking.

[0166] Furthermore, the insulating film 5 also includes a first auxiliary bending portion 53, which assists in bending at the connection between two adjacent side covering sheets 51. The first auxiliary bending portion 53 extends along the height direction H. The first auxiliary bending portion 53 is provided on the bending body 580 of the bending region 58, that is, along the height direction H, the first auxiliary bending portion 53 is further away from the cover plate body 21 than the protrusion 581.

[0167] Furthermore, along the height direction H, the distance from the end of the first auxiliary bending portion 53 near the protrusion 581 to the lowest position 5811 of the protrusion is d, and the thickness of the side covering piece 51 is t. d and t conform to the following formula:

[0168] 0.6mm 2 ≤t×d≤1.125mm 2 .

[0169] In this way, by setting the range of the product of d and t, the structural strength and tear resistance of this area can be ensured, improving the reliability of the insulating film 5 and the safety of the battery while avoiding any impact on the battery density. This is because the product of the distance d from the end of the first auxiliary bending portion 53 near the protrusion 581 to the lowest position 5811 of the protrusion and the thickness t of the side covering sheet 51 is the cross-sectional area at the lowest position 5811 of the protrusion, and the size of the cross-sectional area determines the structural strength and tear resistance at that position. By limiting the range of the product of d and t to be greater than or equal to 0.6 mm... 2 This ensures that the cross-sectional area can guarantee the structural strength and tear resistance of the region; the larger the range of values ​​for this cross-sectional area, the larger the space it occupies, thus affecting the battery density. Therefore, the product of d and t is limited to a value less than or equal to 1.125 mm. 2 This avoids affecting battery density. Furthermore, as shown by the formula, when the thickness t of the side covering 51 decreases, the corresponding increase in distance d ensures that the position corresponding to the cross-sectional area achieves effective structural strength and tear resistance. It should be noted that since the lowest position 5811 of the protrusion is the connection point with the upper edge 510 of the side covering 510, and the upper edge 510 of the side covering 510 forms an insulating film opening 52, the distance d from the end of the first auxiliary bending portion 53 near the protrusion 581 to the lowest position 5811 of the protrusion is, the distance d from the end of the first auxiliary bending portion 53 near the insulating film opening 52 to the insulating film opening 52.

[0170] Furthermore, in this embodiment, the first auxiliary bending portion 53 includes a plurality of weak portions 531 spaced apart along the height direction H. Along the height direction H, the distance d from the weakest portion 531 closest to the protrusion 581 to the lowest position 5811 of the protrusion is the weakest portion 531.

[0171] The thickness of the weak portion 531 is less than the thickness of other areas of the side covering sheet 51. The weak portion 531 can be formed by rolling on the insulating film 5 using a structure such as gears, thereby making it easier to bend the connection between the two side covering sheets 51 at the location of the weak portion 531. However, it is not limited to this. In other embodiments, the weak portion 531 is a hollow structure (cutout). The shape of the weak portion 531 is elongated, and the length direction of the elongated shape is in the same direction as the height direction H of the single cell 100.

[0172] However, this is not the only possibility. In other embodiments, the first auxiliary bending portion 53 may also be a continuous structure. The thickness of this continuous structure is less than the thickness of other areas of the side covering sheet 51.

[0173] Furthermore, along the circumferential direction, the center line P of the protrusion 581 coincides with the extension line of the center line of the first auxiliary bending portion 53, so that the protrusion 581 can better ensure the structural strength and tear resistance of the area, improve the reliability of the insulating film 5 and the safety of the battery.

[0174] A second auxiliary bending portion 57 is provided between the first side covering area 511 and the bottom covering piece 54. The second auxiliary bending portion 57 is used to assist in bending at the connection between the first side covering area 511 and the bottom covering piece 54. The specific structure of the second auxiliary bending portion 57 is the same as that of the first auxiliary bending portion 53.

[0175] This embodiment features a tear-resistant portion that protrudes 581 along the height direction H from the bending body 580 towards the cover plate body 21, extending beyond the upper edge 510 of the side covering sheet. This increases the solid area of ​​the bending region 58, thereby ensuring the structural strength and tear resistance of this region and improving the reliability of the insulating film 5 and the safety of the battery. Furthermore, by positioning the lowest point 5811 of the protrusion closer to the cover plate body 21 than the lower edge 221 of the insulating component, leakage of the cell assembly 4 at the corner edge can be effectively prevented, thus avoiding any impact on the insulating effect of the insulating film 5 between the cell assembly 4 and the casing 1.

[0176] Example 6

[0177] like Figures 18-20 As shown, the overall structure of the insulating film 5 and the single cell 100 in this embodiment is basically the same as that in embodiment 5. The difference is that the tear-resistant part is not a protrusion 581 that protrudes from the bending body 580 toward the cover plate body 21 along the height direction H and extends beyond the upper edge 510 of the side covering sheet, but a groove 582 that is recessed from the bending body 580 away from the cover plate body 21 along the height direction H and is recessed into the upper edge 510 of the side covering sheet. Along the height direction H, the position of the inner wall of the groove 582 furthest from the cover plate body 21 is the lowest position 5821 of the groove, which is closer to the cover plate body 21 than the lower edge 221 of the insulating part.

[0178] In this way, by setting the tear-resistant part as a groove 582 recessed along the height direction H from the bent body 580 away from the cover plate body 21 into the upper edge 510 of the side covering piece, the height difference between the inner wall of the groove 582 and the upper edge 510 of the side covering piece can provide a buffer for the stress on both sides of the side covering piece 51 when the groove 582 is pulled, making the edge of the groove 582 near the cover plate body 21 (i.e., the inner wall of the groove 582) less likely to be torn, thereby affecting the insulation effect at the location of the groove 582; and the groove The lowest position 5821 of the groove is closer to the cover plate body 21 than the lower edge 221 of the insulating component. That is, along the height direction H, the area where the upper edge 510 of the side covering sheet protrudes above the lowest position 5821 of the groove is necessarily closer to the cover plate body 21 than the lower edge 221 of the insulating component. This allows the entire structure of the groove 582 to extend beyond the edge of the bare cell, thereby further ensuring the isolation between the bare cell and the casing by both sides of the groove 582 and the overall insulating film 5, improving the overall insulation effect of the insulating film, and thus enhancing the reliability of the insulating film 5 and the safety of the battery. It should be noted that the edge of the tear-resistant part closest to the cover plate body 21 is the inner wall of the groove 582 in the structure where the tear-resistant part is the groove 582. The position of the tear-resistant part furthest from the cover plate body 21 is the position on the inner wall of the groove 582 furthest from the cover plate body 21 (the lowest position 5821 of the groove) in the structure where the tear-resistant part is the groove 582. The tear-resistant part is located closest to the cover plate body 21. In the structure where the tear-resistant part is a groove 582, it is the position on the inner wall of the groove 582 closest to the cover plate body 21 (the highest position of the groove 582), that is, the connection between the inner wall of the groove 582 and the upper edge 510 of the side covering sheet.

[0179] Along the height direction H, there is a gap between the upper edge 510 of the side cover and the lower edge 211 of the cover body to avoid the upper edge 510 of the side cover interfering with the cover body 21, thereby affecting the complete sealing of the opening at the top of the housing 1 by the cover assembly 2.

[0180] Furthermore, along the height direction H, the distance from the highest point of the groove 582 to the lowest point 5821 of the groove is D, where D ≥ 1.6 mm. The distance D from the highest point to the lowest point 5821 of the groove 582, i.e., the height of the groove 582 along the height direction H, is limited to a distance D greater than or equal to 1.6 mm to ensure that the side covering piece 51 near the groove 582 has an effective height, ensuring an increased solid area of ​​the bending region 58, thereby ensuring the structural strength and tear resistance of this region. Furthermore, 8 mm ≥ D ≥ 1.6 mm. By limiting the specific value range of this distance D, on the one hand, by ensuring that the side covering piece 51 near the groove 582 has an effective height, the solid area of ​​the bending region 58 is increased, thereby ensuring the structural strength and tear resistance of this region; on the other hand, it avoids the side covering piece 51 near the groove 582 being too high, thus preventing interference with the cover plate body 21 and affecting the complete sealing of the opening at the top of the housing 1.

[0181] Furthermore, the inner wall of the groove 582 includes at least a partial arc shape, that is, at least a portion of the inner wall of the groove 582 is an arc-shaped structure. The arc-shaped structure enables the inner wall of the groove 582 to better distribute stress and allows the inner wall of the groove 582 to transition smoothly, reducing the difficulty of component docking.

[0182] The groove 582 can be arc-shaped, rectangular, or polygonal. Arc-shaped grooves include circular arcs, elliptical arcs, or irregular arcs. Preferably, the groove 582 is circular arc-shaped.

[0183] Furthermore, the two ends of the groove 582 along the circumferential direction are respectively located on the two adjacent side covering pieces 51, so as to make the structure of the groove 582 more balanced.

[0184] Furthermore, the connection between the inner wall of the groove 582 and the upper edge 510 of the side covering sheet is a rounded corner structure, so that the connection can better distribute stress and make the connection smooth transition, reducing the difficulty of component docking.

[0185] Furthermore, along the height direction H, the first auxiliary bending portion 53 is further away from the cover plate body 21 than the groove 582.

[0186] Furthermore, the distance from the end of the first auxiliary bending portion 53 near the groove 582 to the lowest position 5821 near the groove is d, and the thickness of the side covering piece 51 is t. d and t conform to the following formula:

[0187] 0.6mm 2 ≤t×d≤1.125mm 2 .

[0188] In this way, by setting the range of values ​​for the product of d and t, the structural strength and tear resistance of this area can be ensured, improving the reliability of the insulating film 5 and the safety of the battery while avoiding any impact on the battery density. It should be noted that since the inner wall of the groove 582 and the upper edge 510 of the side covering sheet form the edge of the insulating film opening 52, the distance d from one end of the first auxiliary bending portion 53 near the groove 582 to the lowest position 5821 near the groove is, in other words, the distance from one end of the first auxiliary bending portion 53 near the insulating film opening 52 to the insulating film opening 52.

[0189] Furthermore, the center line of the groove 582 coincides with the extension line of the center line of the first auxiliary bending portion 53, so that the side covering sheet 51 around the groove 582 can better ensure the structural strength and tear resistance of the area, improve the reliability of the insulating film 5 and the safety of the battery.

[0190] In this embodiment, the tear-resistant portion is provided as a groove 582 recessed along the height direction H from the bending body 580 away from the cover plate body 21 into the upper edge 510 of the side covering sheet. The lowest position 5821 of the groove is closer to the cover plate body 21 than the lower edge 221 of the insulating component, thereby increasing the solid area near the bending area 58. This ensures the structural strength and tear resistance of the area, improves the reliability of the insulating film 5 and the safety of the battery. Furthermore, it can effectively prevent the cell assembly 4 from leaking out at the corner edge, thus affecting the insulating effect of the insulating film 5 between the cell assembly 4 and the shell 1.

[0191] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship of the device or component shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or component 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 utility model.

[0192] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this utility model, but all such changes and modifications fall within the scope of protection of this utility model.

Claims

1. An insulating film for covering an electrode assembly of a single battery, characterized by comprising: The insulating film includes multiple side-covering sheets and a first auxiliary bending portion disposed between two adjacent side-covering sheets. The first auxiliary bending portion is used to assist the bending at the connection between two adjacent side-covering sheets. The side-covering sheets and the first auxiliary bending portion are alternately arranged, and an opening in the insulating film is formed at the same end along the height direction of the insulating film. The first auxiliary bending portion extends along the height direction, and the distance from the end of the first auxiliary bending portion near the opening of the insulating film to the opening of the insulating film is d. The thickness of the side covering sheet is t, and d and t conform to the following formula: 。 2. The insulating film as described in claim 1, characterized in that, t is greater than or equal to 0.05 mm and less than or equal to 0.375 mm; and / or d is greater than or equal to 3 mm and less than or equal to 22.5 mm.

3. The insulating film as described in claim 1, characterized in that, 0.75 mm 2 ≤ t x d ≤ 0.9 mm 2 .

4. The insulating film as described in claim 2, characterized in that, t is greater than or equal to 0.08 mm and less than or equal to 0.15 mm; and / or d is greater than or equal to 9.3 mm and less than or equal to 15 mm.

5. The insulating film according to any one of claims 1-4, characterized in that, The first auxiliary bending portion includes a plurality of weak portions spaced apart along the height direction, and the distance from the weak portion closest to the opening of the insulating film to the opening of the insulating film among the plurality of weak portions is d.

6. The insulating film according to any one of claims 1-4, characterized in that, The insulating film further includes a bottom covering sheet, and multiple side covering sheets are connected to one end of the bottom covering sheet in the height direction. The multiple side covering sheets include a first side covering area respectively disposed at both ends in the width direction of the bottom covering sheet, and a second side covering area respectively disposed at both ends in the length direction of the bottom covering sheet. The first side covering area is connected to the adjacent second side covering area at both ends along the length direction, and the first auxiliary bending portion is disposed between the first side covering area and the adjacent second side covering area. The insulating film further includes a thickening layer, the wall thickness of which is greater than the wall thickness of the side covering sheet; The thickening layer is disposed on the end face of the side covering sheet on the side away from the bottom covering sheet in the height direction, and the thickening layer includes a first thickening layer unit and a second thickening layer unit. The first thickening layer unit is connected to the first side covering area, and the first thickening layer unit extends toward the second side covering area to form the second thickening layer unit. The second thickening layer unit is connected to the second side covering area.

7. The insulating film as described in claim 6, characterized in that, The insulating film satisfies one or more of the following conditions: a1. Define the length of the thickened layer in the height direction as a, where 1.6mm ≤ a ≤ 10mm; b2. Define the length of the first thickening layer unit in the length direction of the bottom covering sheet as b, where 5mm≤b≤20mm; c3. Define the length of the second thickening layer unit in the width direction of the bottom covering sheet as c, where 5mm≤c≤20mm; d4. The wall thickness of the thickened layer is greater than or equal to 0.1 mm; e5. The wall thickness of the side covering sheet is 0.08~0.2mm; f6. The wall thickness of the thickened layer is less than or equal to 0.3 mm.

8. The insulating film as described in claim 6, characterized in that, The side covering sheet and the thickening layer are integrally formed.

9. The insulating film as described in claim 8, characterized in that, The side covering sheet has a body region and a thickened region. The end of the body region away from the bottom covering sheet in the height direction extends outward toward the body region to form the thickened region. The thickened region is folded toward the body region to form the thickened layer.

10. The insulating film as described in claim 6, characterized in that, The thickened layer includes a first part and a second part. The first part is integrally formed with the side covering sheet, and the second part is independent of the side covering sheet, with the second part covering the first part.

11. The insulating film as described in claim 6, characterized in that, The insulating film satisfies one or more of the following conditions: a2. The first auxiliary bending portion is disposed between the first thickening layer unit and the second thickening layer unit; The wall thickness of the first auxiliary bending portion is less than the wall thickness of the first thickened layer unit or the second thickened layer unit; or, the connection portion between the first thickened layer unit and the second thickened layer unit is partially cut to form the first auxiliary bending portion; b2. The end of the thickened layer away from the bottom covering sheet in the wall thickness direction is flush with the end of the side covering sheet away from the bottom covering sheet in the wall thickness direction. Alternatively, the thickened layer extends beyond the end of the side cover sheet in the wall thickness direction of the bottom cover sheet, away from the bottom cover sheet.

12. A single-cell battery, characterized in that, It includes: The housing has an internal cavity and an opening at the top communicating with the cavity; A cover plate assembly is disposed over the opening, the cover plate assembly including a cover plate body and an insulating member, the insulating member being disposed on the side of the cover plate body facing the receiving cavity; The battery cell assembly is housed within the receiving cavity; The insulating film as described in any one of claims 1-11, wherein the insulating film covers the battery cell assembly.

13. The single-cell battery as described in claim 12, characterized in that, Along the height direction, the insulating film has a connection area at one end near the opening of the insulating film, and the connection area is connected to the insulating element; Along the circumferential direction of the opening in the insulating film, the distance between the end of the connecting area near the first auxiliary bending portion and the first auxiliary bending portion is e, where e ≥ 1 mm.

14. The single-cell battery as described in claim 13, characterized in that, 4mm≥e≥3mm.

15. The single-cell battery as described in claim 12, characterized in that, The insulating film further includes a bottom covering sheet, and multiple side covering sheets are connected to one end of the bottom covering sheet in the height direction. The multiple side covering sheets include a first side covering area respectively disposed at both ends in the width direction of the bottom covering sheet, and a second side covering area respectively disposed at both ends in the length direction of the bottom covering sheet. The first side covering area is connected to the adjacent second side covering area at both ends along the length direction, and the first auxiliary bending portion is disposed between the first side covering area and the adjacent second side covering area. The second side covering area includes two side covering units that partially overlap in the length direction. One end of each side covering unit is connected to the corresponding first side covering area in the width direction, and the other end partially overlaps in the length direction to form an overlapping area. An adhesive layer is provided on the overlapping area, which is used to fix the two side covering units forming the overlapping area. The adhesive layer is disposed close to the bottom covering sheet.

16. The single-cell battery as described in claim 15, characterized in that, Along the height direction, the adhesive layer includes a first side near the bottom cover sheet and a second side away from the bottom cover sheet; Along the height direction, the height of the cell assembly is h, and the distance from the second side to the bottom covering sheet is f, where f ≤ 5 / 9h.

17. The single-cell battery as described in claim 16, characterized in that, f≤1 / 3h; and / or, 25mm≤f≤35mm.

18. The single-cell battery as described in claim 12, characterized in that, Along the height direction of the individual battery cell, the edge of the insulating member away from the cover plate body is the lower edge of the insulating member; The insulating film also includes a bent region that connects two adjacent side coverings circumferentially along the opening of the insulating film, at least a portion of the outer surface of the bent region includes an arc surface, and the edge of the side covering near the cover plate body is the upper edge of the side covering. The bending area includes a bending body and a tear-resistant portion connected to the bending body and disposed on one side near the cover plate body. The first auxiliary bending portion is disposed on the bending body. In the height direction, there is a height difference between the edge of the tear-resistant portion on the side near the cover plate body and the upper edge of the side covering sheet. The position of the tear-resistant portion furthest from the cover plate body is closer to the cover plate body than the lower edge of the insulating member.

19. The single-cell battery as described in claim 18, characterized in that, The tear-resistant portion is a protrusion extending from the bending body toward the cover plate body and protruding beyond the upper edge of the side cover sheet along the height direction, and / or the tear-resistant portion is a groove recessed from the bending body toward the upper edge of the side cover sheet along the height direction away from the cover plate body.

20. The single-cell battery as described in claim 19, characterized in that, Along the height direction, the position on the outer edge of the protrusion furthest from the cover plate body is the lowest position of the protrusion, and the position closest to the cover plate body is the highest position of the protrusion. The distance between the highest and lowest positions of the protrusion is D, where 8mm ≥ D ≥ 1.6 mm; or, Along the height direction, the position on the inner wall of the groove furthest from the cover plate body is the lowest position of the groove, and the position closest to the cover plate body is the highest position of the groove. The distance between the highest position and the lowest position of the groove is D, where 8mm ≥ D ≥ 1.6 mm.

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