Insulating film for battery cell housing, battery cell, and secondary battery

Abstract

Provided in the present disclosure are an insulating film for a battery cell housing, a battery cell, and a secondary battery. A first insulating film is used for covering a first side surface; a second insulating film is used for covering a second side surface; a third insulating film is used for at least covering the junction between a third side surface and a bottom surface, and the junction between the third side surface and a top surface, so that the third side surface is partially exposed; and a fourth insulating film is used for at least covering the junction between a fourth side surface and the bottom surface, and the junction between the fourth side surface and the top surface, so that the fourth side surface is partially exposed. The first insulating film, the second insulating film, the third insulating film, and the fourth insulating film are independent of one another and can be directly processed into shapes matching the corresponding side surfaces of the battery cell housing, eliminating the need for further cutting, and reducing the number of folding areas on the insulating film and the number of times the insulating film is folded, thus reducing insulating film waste, reducing costs, and further effectively avoiding an increase in overall battery cell thickness caused by multilayer folding of the insulating film, thereby improving the space utilization rate of the secondary battery.

Description

Insulating film of battery cell shell, battery cell and secondary battery Technical Field

[0001] The present disclosure relates to the technical field of batteries, and in particular to an insulating film of a battery cell shell, a battery cell, and a secondary battery. Background Art

[0002] Secondary batteries typically include multiple sequentially arranged battery cells and a housing for accommodating them. Since the battery cells expand during operation, particularly toward the direction in which the cells are arranged, this can cause the cells to squeeze against each other, impacting their performance and service life. To address this expansion issue, existing technologies typically create gaps between adjacent battery cells. However, this approach fails to secure the cells to each other, necessitating the cells be further mounted on the secondary battery housing. To improve the insulation of the battery cells, the outer periphery of the cell housing is typically coated with an insulating film. However, this film cannot be secured to the secondary battery housing, so it is necessary to ensure that at least a portion of the side of the cell housing is exposed to secure it to the secondary battery housing. Existing insulating films are all monolithic structures, where a large sheet of film is cut, folded, or otherwise wrapped around the entire surface of the cell housing. However, cutting the insulating film can result in some film waste, while folding the film can not only result in some film waste but also increase the thickness of the battery cell, thereby reducing the space utilization of the secondary battery.

[0003] Public content

[0004] The technical problem to be solved by the present disclosure is to overcome the defects of the prior art that the integral insulating film easily causes partial waste of the insulating film and increases the thickness of the battery cell, thereby reducing the space utilization rate of the secondary battery, and to provide an insulating film for a battery cell shell, a battery cell and a secondary battery.

[0005] The present disclosure solves the above technical problems through the following technical solutions:

[0006] An insulating film of a battery cell casing, the battery cell casing comprising opposing bottom and top surfaces, opposing first and second side surfaces, and opposing third and fourth side surfaces, the insulating film of the battery cell casing comprising mutually independent first, second, third, and fourth insulating films;

[0007] The first insulating film and the second insulating film are opposite to each other and spaced apart along a first direction, the first insulating film is used to cover the first side surface, and the second insulating film is used to cover the second side surface;

[0008] The third insulating film and the fourth insulating film are arranged opposite to each other, the third insulating film is used to cover at least the boundary between the third side surface and the bottom surface and the boundary between the third side surface and the top surface, so that the third side surface is partially exposed; the fourth insulating film is used to cover at least the boundary between the fourth side surface and the bottom surface and the boundary between the fourth side surface and the top surface, so that the fourth side surface is partially exposed;

[0009] The first direction is the spacing direction between the first side surface and the second side surface.

[0010] In this solution, the first insulating film, the second insulating film, the third insulating film and the fourth insulating film are independent structures that can be directly processed into a shape that matches the corresponding side of the battery cell shell. No further cutting is required and the folding area and folding times of the insulating film can be reduced, thereby reducing the waste of the insulating film and reducing costs. The reduction in the folding area and folding times can also effectively avoid the increase in the overall thickness of the battery cell due to the multi-layer folding of the insulating film, thereby improving the space utilization of the secondary battery. The exposed portions of the third and fourth side surfaces of the battery shell can be connected to the battery shell of the secondary battery or other adjacent battery cells, thereby improving the connection strength between the battery cell and the battery shell of the secondary battery or the connection strength between the battery cells, enhancing the vibration resistance of the secondary battery, and extending the service life of the secondary battery.

[0011] Preferably, the third insulating film is used to cover part of the third side surface, and the fourth insulating film is used to cover part of the fourth side surface; both ends of the third insulating film and the fourth insulating film in the first direction are connected to the first insulating film and the second insulating film respectively.

[0012] In this solution, the above arrangement avoids the appearance of gaps between the third insulating film and the fourth insulating film and the first insulating film and the second insulating film in the first direction, thereby increasing the creepage distance between the battery cell and the battery housing electrical connector and improving the insulation of the battery cell.

[0013] Preferably, the third insulating film includes a first insulating film unit and a second insulating film unit that are independent of each other, the first insulating film unit and the second insulating film unit are spaced apart along the second direction, the first insulating film unit is used to cover at least the junction between the third side surface and the bottom surface and a portion of the third side surface, and the second insulating film unit is used to cover at least the junction between the third side surface and the top surface and a portion of the third side surface, and both ends of the first insulating film unit and the second insulating film unit in the first direction are connected to the first insulating film and the second insulating film, respectively;

[0014] The fourth insulating film includes a third insulating film unit and a fourth insulating film unit that are independent of each other. The third insulating film unit and the fourth insulating film unit are spaced apart along the second direction. The third insulating film unit is used to cover at least the junction between the fourth side surface and the bottom surface and a portion of the fourth side surface. The fourth insulating film unit is used to cover at least the junction between the fourth side surface and the top surface and a portion of the fourth side surface. Both ends of the third insulating film unit and the fourth insulating film unit in the first direction are connected to the first insulating film and the second insulating film, respectively.

[0015] The second direction is a spacing direction between the bottom surface and the top surface.

[0016] In this solution, the above arrangement enables the first insulating film unit, the second insulating film unit, the third insulating film unit and the fourth insulating film unit to be directly produced and processed as independent structures, thereby reducing the amount of insulating film used and lowering costs.

[0017] Preferably, the first insulating film includes a first side covering area, a second side covering area, a third side covering area, a first bottom covering area and a first top covering area; the first side covering area is used to cover the first side surface; the first side covering area extends toward the third side surface to form the second side covering area, and the second side covering area is used to cover a portion of the third side surface; the first side covering area extends toward the fourth side surface to form the third side covering area, and the third side covering area is used to cover a portion of the fourth side surface; the first side covering area extends toward the bottom surface to form the first bottom covering area, and the first bottom covering area is used to cover at least a portion of the bottom surface; the first side covering area extends toward the top surface to form the first top covering area, and the first top covering area is used to cover at least a portion of the top surface;

[0018] The second insulating film includes a fourth side covering area, a fifth side covering area, a sixth side covering area, a second bottom covering area and a second top covering area; the fourth side covering area is used to cover the second side surface; the fourth side covering area extends toward the third side surface to form the fifth side covering area, and the fifth side covering area is used to cover a portion of the third side surface; the fourth side covering area extends toward the fourth side surface to form the sixth side covering area, and the sixth side covering area is used to cover a portion of the fourth side surface; the fourth side covering area extends toward the bottom surface to form the second bottom covering area, and the second bottom covering area is used to cover at least a portion of the bottom surface; the fourth side covering area extends toward the top surface to form the second top covering area, and the second top covering area is used to cover at least a portion of the top surface;

[0019] The second side cover area and the fifth side cover area are spaced apart in the first direction, and the third side cover area and the sixth side cover area are spaced apart in the first direction.

[0020] In this solution, the above-mentioned setting ensures that all junctions between the first side surface, the second side surface, the third side surface, the fourth side surface, the bottom surface and the top surface are covered with an insulating film, thereby reducing the difficulty of film pasting, improving the flatness of the film pasting, preventing warping and air path phenomena, and avoiding risks such as poor battery cell creepage.

[0021] Preferably, the first insulating film unit includes a seventh side surface covering area and a third bottom surface covering area, the seventh side surface covering area is used to cover a portion of the third side surface, and the second side surface covering area and the fifth side surface covering area both at least partially overlap with the seventh side surface covering area; the seventh side surface covering area extends toward the bottom surface to form the third bottom surface covering area, the third bottom surface covering area is used to cover at least a portion of the bottom surface, and the first bottom surface covering area and the second bottom surface covering area both at least partially overlap with the third bottom surface covering area;

[0022] The second insulating film unit includes an eighth side surface covering area and a third top surface covering area, the eighth side surface covering area is used to cover a portion of the third side surface, and the second side surface covering area and the fifth side surface covering area both at least partially overlap with the eighth side surface covering area; the eighth side surface covering area extends toward the top surface to form the third top surface covering area, the third top surface covering area is used to cover at least a portion of the top surface, and the first top surface covering area and the second top surface covering area both at least partially overlap with the third top surface covering area;

[0023] The third insulating film unit includes a ninth side surface covering region and a fourth bottom surface covering region, wherein the ninth side surface covering region is used to cover a portion of the fourth side surface, and the third side surface covering region and the sixth side surface covering region both at least partially overlap with the ninth side surface covering region; the ninth side surface covering region extends toward the bottom surface to form the fourth bottom surface covering region, and the fourth bottom surface covering region is used to cover at least a portion of the bottom surface, and the first bottom surface covering region and the second bottom surface covering region both at least partially overlap with the fourth bottom surface covering region;

[0024] The fourth insulating film unit includes a tenth side covering area and a fourth top surface covering area, the tenth side covering area is used to cover part of the fourth side surface, and the third side covering area and the sixth side covering area both at least partially overlap with the tenth side covering area; the tenth side covering area extends toward the top surface to form the fourth top surface covering area, the fourth top surface covering area is used to cover at least part of the top surface, and the first top surface covering area and the second top surface covering area both at least partially overlap with the fourth top surface covering area.

[0025] In this solution, the above-mentioned setting can ensure that the junctions of the third side surface and the fourth side surface with the bottom surface and the top surface are all covered by the insulating film, reducing the difficulty of film pasting, improving the flatness of the film pasting, preventing warping and air path phenomena, and avoiding risks such as poor battery cell creepage.

[0026] Preferably, at least one of the third insulating film and the fourth insulating film covers one end surface of the first insulating film and the second insulating film away from the battery cell shell, and the third insulating film and / or the fourth insulating film has an adhesive layer on one end surface facing the first insulating film and the second insulating film.

[0027] In this solution, the third insulating film and the fourth insulating film can serve as fixing structures for the first insulating film and the second insulating film to fix the insulating film of the entire battery cell shell, so that the first insulating film and the second insulating film no longer need to be fixed with a separate fixing structure to achieve fixation relative to the battery cell shell, thereby simplifying the assembly process and reducing costs.

[0028] Preferably, the first bottom surface covering area and the second bottom surface covering area are spaced apart in the first direction, and the third insulating film and the fourth insulating film are spaced apart in the third direction, so that the bottom surface is partially exposed;

[0029] Wherein, the third direction is the spacing direction between the third side surface and the fourth side surface.

[0030] In this solution, the exposed portion of the bottom surface of the battery shell can be thermally connected to the battery shell of the secondary battery or other adjacent battery cells, which can improve the heat transfer efficiency, improve the sealing and durability of the secondary battery, and protect the secondary battery.

[0031] A battery cell, comprising a battery cell housing, a battery cell assembly, and the insulating film of the battery cell housing as described above, wherein the battery cell assembly is accommodated in the battery cell housing, and the insulating film of the battery cell housing is coated on the outer surface of the battery cell housing;

[0032] The outer surface of the battery cell shell includes opposite bottom and top surfaces, opposite first and second side surfaces, and opposite third and fourth side surfaces; the first insulating film covers the first side surface; the second insulating film covers the second side surface; the third insulating film at least covers the junction between the third side surface and the bottom surface and the junction between the third side surface and the top surface, so that the third side surface is partially exposed; the fourth insulating film at least covers the junction between the fourth side surface and the bottom surface and the junction between the fourth side surface and the top surface, so that the fourth side surface is partially exposed.

[0033] In this solution, an insulating film is coated on the outer surface of the battery cell shell to insulate the battery cell. The first insulating film, the second insulating film, the third insulating film and the fourth insulating film are independent structures and can be directly processed into shapes that match the corresponding sides of the battery cell shell without further cutting and can reduce the folding area and the number of folds of the insulating film, thereby reducing the waste of the insulating film and reducing costs. The reduction in the folding area and the number of folds can also effectively avoid the increase in the overall thickness of the battery cell due to the multi-layer folding of the insulating film, thereby improving the space utilization of the secondary battery. The exposed portions of the third and fourth side surfaces of the battery shell can be connected to the battery shell of the secondary battery or other adjacent battery cells, thereby improving the connection strength between the battery cell and the battery shell of the secondary battery or the connection strength between the battery cells, enhancing the vibration resistance of the secondary battery, and extending the service life of the secondary battery.

[0034] A secondary battery comprises a battery housing and a plurality of battery cells as described above, wherein the battery housing has a receiving cavity, the plurality of battery cells are received in the receiving cavity, and the plurality of battery cells are arranged in sequence along the first direction.

[0035] In this solution, the above-mentioned battery cell is used so that the battery cell shell can expose the third side and the fourth side for connection with the battery shell or other adjacent battery cells, thereby improving the connection strength between the battery cell and the battery shell of the secondary battery or the connection strength between the battery cells, enhancing the vibration resistance of the secondary battery, and extending the service life of the secondary battery.

[0036] Preferably, the secondary battery meets one or more of the following conditions:

[0037] a. The third side surface and / or the fourth side surface are partially exposed to form a first connecting portion of the battery cell housing, and a fixing adhesive layer is provided on the first connecting portion, and the battery cell is bonded to the inner wall of the accommodating cavity or the adjacent battery cell through the fixing adhesive layer;

[0038] b. The bottom portion is exposed to form a second connecting portion of the battery cell housing, and a thermal conductive adhesive layer is provided on the second connecting portion. The battery cell is bonded to the inner wall of the accommodating cavity or the adjacent battery cell through the thermal conductive adhesive layer.

[0039] In this solution, the battery cells are connected to the battery casing of the secondary battery, which can improve the connection strength between the battery cells and the battery casing, enhance the secondary battery's vibration resistance, and extend the service life of the secondary battery. Connecting the battery cells to the battery casing or between the battery cells using thermally conductive adhesive can improve heat transfer efficiency, improve the sealing and durability of the secondary battery, and protect the secondary battery.

[0040] The positive progressive effect of the present disclosure is that the first insulating film, the second insulating film, the third insulating film and the fourth insulating film can be directly processed into a shape that is compatible with the corresponding side of the battery cell shell as independent structures, without the need for further cutting and can reduce the folding area and the number of foldings of the insulating film, thereby reducing the waste of the insulating film and reducing costs. The reduction in the folding area and the number of foldings can also effectively avoid the increase in the overall thickness of the battery cell due to the multi-layer folding of the insulating film, thereby improving the space utilization rate of the secondary battery. The exposed portions of the third and fourth side surfaces of the battery shell can be connected to the battery shell of the secondary battery or other adjacent battery cells, thereby improving the connection strength between the battery cell and the battery shell of the secondary battery or the connection strength between the battery cells, enhancing the vibration resistance of the secondary battery, and extending the service life of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG1 is a schematic diagram of the internal structure of a secondary battery according to an embodiment of the present disclosure.

[0042] FIG2 is a schematic diagram of the three-dimensional structure of a battery cell according to an embodiment of the present disclosure.

[0043] FIG. 3 is a schematic diagram of an expanded first insulating film according to an embodiment of the present disclosure.

[0044] FIG4 is a schematic diagram of an expanded first insulating film unit according to an embodiment of the present disclosure.

[0045] FIG5 is a schematic diagram of the steps of the insulating film and battery cell shell coating process according to an embodiment of the present disclosure.

[0046] FIG6 is a schematic diagram of another step of the process of coating the insulating film and the battery cell shell according to an embodiment of the present disclosure.

[0047] FIG. 7 is a schematic diagram of another step of the insulating film and cell shell coating process according to an embodiment of the present disclosure.

[0048] FIG8 is a schematic diagram of another step of the insulating film and cell shell coating process according to an embodiment of the present disclosure.

[0049] FIG9 is a schematic diagram of another step of the insulating film and cell shell coating process according to an embodiment of the present disclosure.

[0050] Description of reference numerals:

[0051] Battery case 1, accommodating cavity 11, battery cell 2, battery cell case 21, bottom surface 211, top surface 212, first side surface 213, second side surface 214, third side surface 215, fourth side surface 216, first connecting portion 217, second connecting portion 218, insulating film 3, first insulating film 31, first side covering area 311, second side covering area 312, third side covering area 313, first bottom covering area 314, first top covering area 315, second insulating film 32, fourth side covering area 321, fifth side covering area 322, sixth side surface covering area 323, second bottom surface covering area 324, second top surface covering area 325, third insulating film 33, first insulating film unit 331, seventh side covering area 3311, third bottom surface covering area 3312, second insulating film unit 332, eighth side covering area 3321, third top surface covering area 3322, fourth insulating film 34, third insulating film unit 341, ninth side covering area 3411, fourth bottom surface covering area 3412, fourth insulating film unit 342, tenth side covering area 3421, fourth top surface covering area 3422. DETAILED DESCRIPTION

[0052] A preferred embodiment is given below, and the present disclosure is described more clearly and completely in conjunction with the accompanying drawings.

[0053] As shown in Figures 1 and 2, this embodiment discloses a secondary battery for powering electric vehicles and other electrical equipment. The secondary battery includes a battery housing 1 and a plurality of battery cells 2. The battery housing 1 is used to accommodate and protect the plurality of battery cells 2.

[0054] As shown in FIG1 , the battery housing 1 has a receiving cavity 11 inside, and multiple battery cells 2 are received in the receiving cavity 11 . The battery cells 2 are fixedly connected to the battery housing 1 to prevent the battery cells 2 from detaching from the battery housing 1 and avoiding failure of the secondary battery.

[0055] As shown in Figures 2 and 5, the battery cell 2 includes a battery cell housing 21, a battery cell assembly (not shown), and an insulating film 3 of the battery cell housing 21. The battery cell assembly is accommodated in the battery cell housing 21, and the insulating film 3 of the battery cell housing 21 is coated on the outer surface of the battery cell housing 21. Specifically, the outer surface of the battery cell housing 21 includes a bottom surface 211 and a top surface 212 arranged opposite to each other along a horizontal plane, a first side surface 213 and a second side surface 214 arranged opposite to each other along a third direction (the Y direction in Figure 2), and a third side surface 215 and a fourth side surface 216 arranged opposite to each other along a first direction (the X direction in Figure 2). The lower ends of the first side surface 213, the second side surface 214, the third side surface 215 and the fourth side surface 216 are all connected to the bottom surface 211, the upper ends of the first side surface 213, the second side surface 214, the third side surface 215 and the fourth side surface 216 are all connected to the top surface 212, and the ends of the first side surface 213 and the second side surface 214 in the third direction are respectively connected to the third side surface 215 and the fourth side surface 216 to enclose the battery case 1 in the shape of a cuboid.

[0056] As shown in FIG2 , in this embodiment, the widths of the first side surface 213 and the second side surface 214 are equal, and the widths of the third side surface 215 and the fourth side surface 216 are equal, and the widths of the first side surface 213 and the second side surface 214 are greater than the widths of the third side surface 215 and the fourth side surface 216. The first direction is the spacing direction between the first side surface 213 and the second side surface 214, i.e., the thickness direction of the battery cell 2; the second direction (the Z direction in FIG2 ) is the spacing direction between the bottom surface 211 and the top surface 212, i.e., the height direction of the battery cell 2; the third direction is the spacing direction between the third side surface 215 and the fourth side surface 216, i.e., the length direction of the battery cell 2; the first and third directions are two mutually perpendicular directions in the same horizontal plane, and the second direction is perpendicular to the plane formed by the first and third directions.

[0057] In other alternative embodiments, the width of the first side 213 and the second side 214 may be smaller than the width of the third side 215 and the fourth side 216. In this state, the second direction is still the height direction of the battery cell 2, but the first direction is the length direction of the battery cell 2, and the third direction is the thickness direction of the battery cell 2.

[0058] As shown in Figures 2 to 4, the insulating film 3 of the battery cell shell 21 includes a first insulating film 31, a second insulating film 32, a third insulating film 33 and a fourth insulating film 34 that are independent of each other. Independence in this embodiment means that the first insulating film 31, the second insulating film 32, the third insulating film 33 and the fourth insulating film 34 are all independent components that can be produced and processed separately, and then assembled to form the insulating film 3 of the battery cell shell 21 after molding.

[0059] When the insulating film 3 is wrapped around the cell case 21 , the insulating film 3 is in use. In this state, the first insulating film 31 and the second insulating film 32 are opposite to each other and spaced apart along the first direction, the first insulating film 31 completely covers the first side surface 213, and the second insulating film 32 completely covers the second side surface 214; the third insulating film 33 and the fourth insulating film 34 are opposite to each other, the third insulating film 33 covers the junction between the third side surface 215 and the bottom surface 211 (that is, the edge formed by the intersection of the third side surface 215 and the bottom surface 211) and the junction between the third side surface 215 and the top surface 212 (that is, the edge formed by the intersection of the third side surface 215 and the top surface 212), so that the third side surface 215 is partially exposed; the fourth insulating film 34 covers the junction between the fourth side surface 216 and the bottom surface 211 (that is, the edge formed by the intersection of the fourth side surface 216 and the bottom surface 211) and the junction between the fourth side surface 216 and the top surface 212 (that is, the edge formed by the intersection of the fourth side surface 216 and the top surface 212), so that the fourth side surface 216 is partially exposed.

[0060] The first, second, third, and fourth insulating films 31, 32, 33, and 34, as independent structures, can be directly processed into shapes that conform to the corresponding sides of the cell casing 21, eliminating the need for further cutting. This reduces the folding area and number of folds of the insulating film 3, thereby reducing waste and lowering costs. This reduction in folding area and number of folds also effectively avoids the increase in overall cell 2 thickness caused by multiple layers of folding of the insulating film 3, thereby improving the space utilization of the secondary battery.

[0061] The portion of the third side 215 where the insulating film 3 is exposed and the portion of the fourth side 216 where the insulating film 3 is exposed both form a first connecting portion 217, and the battery cell 2 is connected to the battery case 1 of the secondary battery or other adjacent battery cells 2 through the first connecting portion 217, thereby improving the connection strength between the battery cell 2 and the battery case 1 of the secondary battery or the connection strength between the battery cells 2 and the battery cells 2, enhancing the vibration resistance of the secondary battery, and extending the service life of the secondary battery.

[0062] Specifically, as shown in Figures 2 and 3, the first insulating film 31 includes a first side covering area 311, a second side covering area 312, a third side covering area 313, a first bottom covering area 314, and a first top covering area 315. The first side covering area 311 completely covers the first side 213. The first side covering area 311 extends toward the third side 215 to form the second side covering area 312, and the second side covering area 312 partially covers the third side 215, so that the intersection of the first side 213 and the third side 215 (i.e., the edge formed by the intersection of the first side 213 and the third side 215) can be completely covered by the first insulating film 31, reducing the difficulty of film application, improving the flatness of the film, preventing warping and air path phenomena, and avoiding risks such as poor creepage of the battery cell 2. The first side covering area 311 extends toward the fourth side 216 to form a third side covering area 313. The third side covering area 313 partially covers the fourth side 216, so that the intersection of the first side 213 and the fourth side 216 (i.e., the edge formed by the intersection of the first side 213 and the fourth side 216) can be completely covered by the first insulating film 31, thereby reducing the difficulty of film application, improving the flatness of the film application, preventing warping and air path phenomena, and avoiding risks such as poor creepage of the battery cell 2. The first side covering area 311 extends toward the bottom surface 211 to form a first bottom surface covering area 314. The first bottom surface covering area 314 is used to cover at least a portion of the bottom surface 211, so that the intersection of the first side 213 and the bottom surface 211 (i.e., the edge formed by the intersection of the first side 213 and the bottom surface 211) can be completely covered by the first insulating film 31, reducing the difficulty of film application, improving the flatness of the film application, preventing warping and air path phenomena, and avoiding risks such as poor creepage of the battery cell 2. The first side covering area 311 extends toward the top surface 212 to form a first top surface covering area 315. The first top surface covering area 315 is used to cover part of the top surface 212 so that the junction of the first side surface 213 and the top surface 212 (i.e., the edge formed by the intersection of the first side surface 213 and the third side surface 215) can be completely covered by the first insulating film 31, thereby reducing the difficulty of film pasting, improving the flatness of the film, preventing warping and air path phenomena, and avoiding risks such as poor creepage of the battery cell 2.

[0063] As shown in Figures 2 and 5, the shape of the second insulating film 32 in this embodiment is identical to that of the first insulating film 31. The second insulating film 32 includes a fourth side cover area 321, a fifth side cover area 322, a sixth side cover area 323, a second bottom cover area 324, and a second top cover area 325. The fourth side cover area 321 is opposite the first side cover area 311, the fifth side cover area 322 is opposite the second side cover area 312, the sixth side cover area 323 is opposite the third side cover area 313, the second bottom cover area 324 is opposite the first bottom cover area 314, and the second top cover area 325 is opposite the first top cover area 315. The fourth side cover area 321 completely covers the second side surface 214. The fourth side covering area 321 extends toward the third side 215 to form a fifth side covering area 322. The fifth side covering area 322 partially covers the third side 215, so that the intersection of the second side 214 and the third side 215 (i.e., the edge formed by the intersection of the second side 214 and the third side 215) can be completely covered by the second insulating film 32, thereby reducing the difficulty of film application, improving the flatness of the film application, preventing warping and air path phenomena, and avoiding risks such as poor creepage of the battery cell 2. The fourth side covering area 321 extends toward the fourth side 216 to form a sixth side covering area 323. The sixth side covering area 323 partially covers the fourth side 216, so that the intersection of the second side 214 and the fourth side 216 (i.e., the edge formed by the intersection of the second side 214 and the fourth side 216) can be completely covered by the second insulating film 32, reducing the difficulty of film application, improving the flatness of the film application, preventing warping and air path phenomena, and avoiding risks such as poor creepage of the battery cell 2. The fourth side covering area 321 extends toward the bottom surface 211 to form a second bottom surface covering area 324. The second bottom surface covering area 324 covers a portion of the bottom surface 211 so that the junction of the second side surface 214 and the bottom surface 211 (that is, the edge formed by the intersection of the second side surface 214 and the bottom surface 211) can be completely covered by the second insulating film 32, thereby reducing the difficulty of film pasting, improving the flatness of the film, preventing warping and air path phenomena, and avoiding risks such as poor creepage of the battery cell 2. The fourth side covering area 321 extends toward the top surface 212 to form a second top surface covering area 325. The second top surface covering area 325 covers a portion of the top surface 212 so that the junction of the second side surface 214 and the top surface 212 (i.e., the edge formed by the intersection of the second side surface 214 and the third side surface 215) can be completely covered by the second insulating film 32, thereby reducing the difficulty of film pasting, improving the flatness of the film, preventing warping and air path phenomena, and avoiding risks such as poor creepage of the battery cell 2.

[0064] In other alternative embodiments, the shape of the second insulating film 32 may not be completely the same as the shape of the first insulating film 31 , and may be specifically designed according to the shape of the battery cell housing 21 .

[0065] As shown in Figure 2, the third insulating film 33 covers part of the third side surface 215, and the fourth insulating film 34 covers part of the fourth side surface 216; the third insulating film 33 and the fourth insulating film 34 are respectively connected to the first insulating film 31 and the second insulating film 32 at both ends in the first direction to avoid gaps between the third insulating film 33 and the fourth insulating film 34 and the first insulating film 31 and the second insulating film 32 in the first direction, thereby increasing the creepage distance between the battery cell 2 and the electrical connector of the battery case 1 and improving the insulation of the battery cell 2.

[0066] As shown in FIG2 , the third insulating film 33 includes a first insulating film unit 331 and a second insulating film unit 332, which are independent of each other. The first insulating film unit 331 and the second insulating film unit 332 are spaced apart along the second direction so that the third side surface 215 can be partially exposed to form the first connecting portion 217. Both ends of the first insulating film unit 331 and the second insulating film unit 332 in the first direction are connected to the first insulating film 31 and the second insulating film 32, respectively. The fourth insulating film 34 includes a third insulating film unit 341 and a fourth insulating film unit 342, which are independent of each other. The third insulating film unit 341 and the fourth insulating film unit 342 are spaced apart along the second direction so that the fourth side surface 216 can be partially exposed to form the first connecting portion 217. Both ends of the third insulating film unit 341 and the fourth insulating film unit 342 in the first direction are connected to the first insulating film 31 and the second insulating film 32, respectively. Independence in this embodiment means that the first insulating film unit 331, the second insulating film unit 332, the third insulating film unit 341 and the fourth insulating film unit 342 are all independent components that can be produced and processed separately, and then assembled to form the insulating film 3 of the battery shell 1 after molding, thereby reducing the use of the insulating film 3 and reducing costs.

[0067] Specifically, as shown in Figure 4, the first insulating film unit 331 includes a seventh side covering area 3311 and a third bottom covering area 3312. The seventh side covering area 3311 partially covers the third side surface 215. The second side covering area 312 and the fifth side covering area 322 both at least partially overlap with the seventh side covering area 3311, thereby preventing a gap from forming between the first insulating film unit 331 and the first and second insulating films 31 and 32 in the first direction. This increases the creepage distance between the battery cell 2 and the electrical connector of the battery housing 1, thereby improving the insulation performance of the battery cell 2. The seventh side covering area 3311 extends toward the bottom surface 211 to form a third bottom covering area 3312. The third bottom covering area 3312 partially covers the bottom surface 211, allowing the intersection of the third side surface 215 and the bottom surface 211 (i.e., the edge formed by the intersection of the third side surface 215 and the bottom surface 211) to be completely covered by the first insulating film unit 331. This reduces the difficulty of film application, improves the flatness of the film, prevents warping and air path phenomena, and avoids risks such as poor creepage of the battery cell 2. The first bottom covering area 314 and the second bottom covering area 324 both partially overlap with the third bottom covering area 3312 to avoid gaps at the intersection, increase the creepage distance between the battery cell 2 and the electrical connector of the battery case 1, and improve the insulation of the battery cell 2.

[0068] As shown in Figure 2, the shape of the second insulating film unit 332 in this embodiment is identical to that of the first insulating film unit 331. The second insulating film unit 332 includes an eighth side covering area 3321 and a third top covering area 3322. The eighth side covering area 3321 is opposite to the seventh side covering area 3311, and the third top covering area 3322 is opposite to the third bottom covering area 3312. The eighth side covering area 3321 partially covers the third side surface 215. The second side covering area 312 and the fifth side covering area 322 both partially overlap with the eighth side covering area 3321, preventing a gap from forming between the second insulating film unit 332 and the first and second insulating films 31 and 32 in the first direction. This increases the creepage distance between the battery cell 2 and the electrical connector of the battery case 1, thereby improving the insulation performance of the battery cell 2. The eighth side covering area 3321 extends toward the top surface 212 to form a third top surface covering area 3322. The third top surface covering area 3322 partially covers the top surface 212, so that the intersection of the third side surface 215 and the top surface 212 (i.e., the edge formed by the intersection of the third side surface 215 and the top surface 212) can be completely covered by the second insulating film unit 332. This reduces the difficulty of film application, improves the flatness of the film, prevents warping and air path phenomena, and avoids risks such as poor creepage of the battery cell 2. The first top surface covering area 315 and the second top surface covering area 325 both at least partially overlap with the third top surface covering area 3322 to avoid gaps at the intersection, increase the creepage distance between the battery cell 2 and the electrical connector of the battery case 1, and improve the insulation of the battery cell 2.

[0069] As shown in Figure 2, the shape of the third insulating film unit 341 in this embodiment is identical to that of the first insulating film unit 331. The third insulating film unit 341 includes a ninth side covering region 3411 and a fourth bottom covering region 3412. The ninth side covering region 3411 is opposite the seventh side covering region 3311, and the fourth bottom covering region 3412 is opposite the third bottom covering region 3312. The ninth side covering region 3411 partially covers the fourth side surface 216. The third side covering region 313 and the sixth side covering region 323 both at least partially overlap with the ninth side covering region 3411, preventing a gap from forming between the third insulating film unit 341 and the first and second insulating films 31 and 32 in the first direction. This increases the creepage distance between the battery cell 2 and the electrical connector of the battery housing 1, thereby improving the insulation performance of the battery cell 2. The ninth side covering area 3411 extends toward the bottom surface 211 to form a fourth bottom covering area 3412. The fourth bottom covering area 3412 is used to cover a portion of the bottom surface 211, so that the intersection of the fourth side surface 216 and the bottom surface 211 (i.e., the edge formed by the intersection of the fourth side surface 216 and the bottom surface 211) can be completely covered by the third insulating film unit 341. This reduces the difficulty of film application, improves the flatness of the film, prevents warping and air path phenomena, and avoids risks such as poor creepage of the battery cell 2. The first bottom covering area 314 and the second bottom covering area 324 both at least partially overlap with the fourth bottom covering area 3412 to avoid gaps at the intersection, increase the creepage distance between the battery cell 2 and the electrical connector of the battery case 1, and improve the insulation of the battery cell 2.

[0070] As shown in Figure 2, the shape of the fourth insulating film unit 342 in this embodiment is identical to that of the first insulating film unit 331. The fourth insulating film unit 342 includes a tenth side covering region 3421 and a fourth top covering region 3422. The tenth side covering region 3421 is opposite the seventh side covering region 3311, and the fourth top covering region 3422 is opposite the third bottom covering region 3312. The tenth side covering region 3421 partially covers the fourth side surface 216. The third side covering region 313 and the sixth side covering region 323 both at least partially overlap with the tenth side covering region 3421, preventing a gap between the fourth insulating film unit 342 and the first and second insulating films 31 and 32 in the first direction. This increases the creepage distance between the battery cell 2 and the electrical connector of the battery housing 1, thereby improving the insulation performance of the battery cell 2. The tenth side surface covering area 3421 extends toward the top surface 212 to form a fourth top surface covering area 3422. The fourth top surface covering area 3422 is used to cover a portion of the top surface 212, so that the intersection of the fourth side surface 216 and the top surface 212 (i.e., the edge formed by the intersection of the fourth side surface 216 and the top surface 212) can be completely covered by the fourth insulating film unit 342. This reduces the difficulty of film application, improves the flatness of the film, prevents warping and air path phenomena, and avoids risks such as poor creepage of the battery cell 2. The first top surface covering area 315 and the second top surface covering area 325 both at least partially overlap with the fourth top surface covering area 3422 to avoid gaps at the intersection, increase the creepage distance between the battery cell 2 and the electrical connector of the battery case 1, and improve the insulation of the battery cell 2.

[0071] As shown in FIG2 , the second side covering area 312 and the fifth side covering area 322 are spaced apart in the first direction, and the seventh side covering area 3311 and the eighth side covering area 3321 are spaced apart in the second direction, so that the third side 215 is partially exposed to form the first connecting portion 217. The third side covering area 313 and the sixth side covering area 323 are spaced apart in the first direction, and the ninth side covering area 3411 and the tenth side covering area 3421 are spaced apart in the second direction, so that the fourth side 216 is partially exposed to form the first connecting portion 217.

[0072] As shown in Figure 2, the first bottom surface covering area 314 and the second bottom surface covering area 324 are spaced apart in the first direction, and the third bottom surface covering area 3312 and the fourth bottom surface covering area 3412 are spaced apart in the third direction, so that a portion of the bottom surface 211 is exposed to form a second connecting portion 218. The second connecting portion 218 can be thermally connected to the battery case 1 of the secondary battery or other adjacent battery cells 2, which can improve the heat transfer efficiency, improve the sealing and durability of the secondary battery, and play a role in protecting the secondary battery.

[0073] In other alternative embodiments, the first insulating film unit 331 may also cover the junction of the third side surface 215 and the bottom surface 211, or only cover a portion of the third side surface 215 and the junction of the third side surface 215 and the bottom surface 211, or only cover a portion of the bottom surface 211 and the junction of the third side surface 215 and the bottom surface 211. The second insulating film unit 332 may also cover the junction of the third side surface 215 and the top surface 212, or only cover a portion of the third side surface 215 and the junction of the third side surface 215 and the top surface 212, or only cover a portion of the top surface 212 and the junction of the third side surface 215 and the top surface 212. The third insulating film unit 341 may also cover the junction between the fourth side surface 216 and the bottom surface 211, or only cover a portion of the fourth side surface 216 and the junction between the fourth side surface 216 and the bottom surface 211, or only cover a portion of the bottom surface 211 and the junction between the fourth side surface 216 and the bottom surface 211. The fourth insulating film unit 342 may also cover the junction between the fourth side surface 216 and the top surface 212, or only cover a portion of the fourth side surface 216 and the junction between the fourth side surface 216 and the top surface 212, or only cover a portion of the top surface 212 and the junction between the fourth side surface 216 and the top surface 212.

[0074] In other alternative embodiments, the first bottom surface covering area 314 and / or the second bottom surface covering area 324 and / or the third bottom surface covering area 3312 and / or the fourth bottom surface covering area 3412 may also completely cover the bottom surface 211 of the battery cell housing 21, so that the battery cell 2 can only be connected to the battery housing 1 of the secondary battery or other adjacent battery cells 2 via the first connecting portion 217. The first bottom surface covering area 314 and / or the second bottom surface covering area 324 and / or the third bottom surface covering area 3312 and / or the fourth bottom surface covering area 3412 may also completely overlap with each other.

[0075] In other alternative embodiments, the first top surface covering area 315 and / or the second top surface covering area 325 and / or the third top and bottom surface 211 covering area and / or the fourth top surface covering area 3422 may also completely cover the top surface 212 of the battery cell housing 21. However, the term "complete coverage" herein refers to the complete coverage of the top surface 212 except for the electrodes, electrolyte inlet, and other structures that need to be exposed. The first top surface covering area 315 and / or the second top surface covering area 325 and / or the third top and bottom surface 211 covering area and / or the fourth top surface covering area 3422 may also completely overlap with each other.

[0076] Furthermore, the third insulating film 33 and the fourth insulating film 34 both cover the end surface of the first insulating film 31 and the second insulating film 32 away from the battery cell shell 21, and the end surfaces of the third insulating film 33 and the fourth insulating film 34 facing the first insulating film 31 and the second insulating film 32 both have an adhesive layer. The third insulating film 33 and the fourth insulating film 34 are fixedly connected to the first insulating film 31, the second insulating film 32 and the battery cell shell 21 through the adhesive layer, thereby fixing the insulating film 3 of the entire battery cell shell 21 relative to the battery cell shell 21, and thus making it possible for the first insulating film 31 and the second insulating film 32 to be fixed relative to the battery cell shell 21 without having to set up a separate fixing structure, thereby simplifying the assembly process and reducing costs.

[0077] In this embodiment, the first insulating film 31 and the second insulating film 32 are completely fixed by the third insulating film 33 and the fourth insulating film 34. In other alternative embodiments, a fixing structure can also be provided on the first insulating film 31 and the second insulating film 32 to achieve a fixed connection with the battery cell housing 21.

[0078] The third insulating film 33 and the fourth insulating film 34 in this embodiment are specifically a single-sided tape, with the sticky side of the tape forming an adhesive layer. In other alternative embodiments, the third insulating film 33 and the fourth insulating film 34 can also be disposed on the end surface of the first insulating film 31 and the second insulating film 32 facing the battery cell housing 21. In this case, the portion of the third insulating film 33 and the fourth insulating film 34 that overlaps with the first insulating film 31 and the second insulating film 32 can be secured using double-sided tape, or a fixing structure can be provided on the first insulating film 31 and the second insulating film 32 to achieve a fixed connection with the third insulating film 33 and the fourth insulating film 34.

[0079] The third insulating film 33 and the fourth insulating film 34 in this embodiment are the same. In other alternative embodiments, the structures of the third insulating film 33 and the fourth insulating film 34 may also be different. For example, one of them is a single-sided tape and covers the end surface of the first insulating film 31 and the second insulating film 32 away from the battery cell case 21, and the other is a double-sided tape and covers the end surface of the first insulating film 31 and the second insulating film 32 facing the battery cell case 21.

[0080] As shown in FIG1 , a plurality of battery cells 2 are arranged sequentially along a first direction, i.e., for two adjacent battery cells 2, the first side surface 213 of one battery cell housing 21 is adjacent to the second side surface 214 of the other battery cell housing 21. The third side surface 215 and the fourth side surface 216 of the battery cell housing 21 both have a first connection portion 217 exposed from the insulating film 3. A fixing adhesive layer is provided on the first connection portion 217. The battery cells 2 are directly bonded to the inner wall of the corresponding accommodating cavity 11 via the fixing adhesive layer to achieve a fixed connection between the battery cells 2 and the battery housing 1, thereby improving the connection strength between the battery cells 2 and the battery housing 1 of the secondary battery, enhancing the vibration resistance of the secondary battery, and extending the service life of the secondary battery. The fixing adhesive layer can be formed by applying fixing glue to the first connection portion 217.

[0081] In other alternative embodiments, only the third side 215 or the fourth side 216 of the battery cell shell 21 may be provided with a first connecting portion 217 bonded to the inner wall of the accommodating cavity 11. In this embodiment, both the third side 215 and the fourth side 216 of the battery cell shell 21 are provided with a first connecting portion 217 bonded to the inner wall of the accommodating cavity 11 in order to further enhance the connection strength between the battery cell 2 and the battery shell 1, enhance the vibration resistance of the secondary battery, and extend the service life of the secondary battery.

[0082] In other alternative embodiments, multiple battery cells 2 may be arranged along a third direction. In this case, the first connecting portions 217 on the third side 215 and the fourth side 216 may be used to bond adjacent battery cells 2. Connecting battery cells 2 to each other can reduce collisions between battery cells 2, enhance the vibration resistance of the secondary battery, and extend the service life of the secondary battery. Alternatively, the first connecting portions 217 on the third side 215 and the fourth side 216 may also be used to connect to other external components.

[0083] As shown in Figure 2, the bottom surface 211 of the battery cell housing 21 has a second connection portion 218 exposed from the insulating film 3. A thermally conductive adhesive layer is provided on the second connection portion 218. The battery cell 2 is directly bonded to the inner wall of the corresponding accommodating cavity 11 via the thermally conductive adhesive layer to achieve a thermal connection between the battery cell 2 and the battery housing 1. The thermally conductive adhesive layer can be formed by applying thermally conductive adhesive to the second connection portion 218.

[0084] Thermally conductive adhesive, as a high-strength, high-temperature resistant, and highly thermally conductive material, can effectively protect the battery cell 2 of a secondary battery. Thermally conductive adhesive can withstand high-temperature environments, reduce temperature differences, and prevent spontaneous combustion or melting of the battery cell 2 and the electrode, thereby enhancing the stability and reliability of the secondary battery. When a secondary battery is working, it generates a large amount of heat. If the heat cannot be dissipated in time, it will cause dangers such as fire and explosion of the secondary battery. Thermally conductive adhesive can serve as an excellent heat conduction medium to quickly transfer the heat inside the secondary battery, thereby ensuring the stable operation of the secondary battery. The high thermal conductivity of thermally conductive adhesive can improve the overall heat dissipation efficiency and heat transfer speed of the secondary battery, thereby enhancing the service life and stability of the secondary battery. In order to ensure the long-term stability of the secondary battery, it is necessary to ensure the sealing inside the secondary battery. Thermally conductive adhesive can fill the gaps and cracks inside the secondary battery to form a high-strength sealing layer to prevent the gas and moisture inside the secondary battery from invading, thereby ensuring the stability of the environment inside the secondary battery. Thermal conductive adhesive has excellent heat resistance, cold resistance and life resistance, and can withstand different temperature and climatic conditions. This enables the thermal conductive adhesive to maintain its original performance and life cycle in a variety of complex environments, thereby extending the service life of secondary batteries.

[0085] In other alternative embodiments, the second connection portion 218 may also be used for thermal connection between adjacent battery cells 2. Alternatively, the second connection portion 218 may also be used for thermal connection with other external components.

[0086] The following briefly describes the process of the insulating film 3 covering the cell shell 21 in combination with the specific structures of the insulating film 3 and the cell shell 21:

[0087] Step S1 , as shown in FIG5 , firstly covers the first side surface 213 with the first insulating film 31 so that the first side surface covering region 311 covers the first side surface 213 ; covers the second side surface 214 with the second insulating film 32 so that the fourth side surface covering region 321 covers the second side surface 214 .

[0088] Step S2, as shown in Figure 6, bend the first insulating film 31 so that the second side 214 covering area covers part of the third side 215, and the third side covering area 313 covers part of the fourth side 216; bend the second insulating film 32 so that the fifth side covering area covers part of the third side 215, and the sixth side covering area 323 covers part of the fourth side 216.

[0089] Step S3 , as shown in FIG7 , bend the first insulating film 31 so that the first bottom surface 211 enclosing region encloses a portion of the bottom surface 211 ; bend the second insulating film 32 so that the second bottom surface 211 enclosing region encloses a portion of the bottom surface 211 .

[0090] It should be understood that in other alternative implementations, step S3 may also be performed before step S2.

[0091] Step S4 , as shown in FIG8 , bend the first insulating film 31 so that the first top surface 212 covering region covers a portion of the top surface 212 ; bend the second insulating film 32 so that the second top surface 212 covering region covers a portion of the top surface 212 .

[0092] It should be understood that in other alternative implementations, step S4 may also be performed before step S3, or step S4 may also be performed before step S2.

[0093] Step S5 , as shown in FIG9 , affix the second insulating film unit 332 and the fourth insulating film unit 342 to the top of the cell casing 21 to fix the upper end of the insulating film 3 .

[0094] Step S6, as shown in FIG2 , affix the first insulating film unit 331 and the third insulating film unit 341 to the bottom of the cell shell 21 to fix the lower end of the insulating film 3 .

[0095] It should be understood that in other alternative implementations, step S6 may also be performed before step S5.

[0096] In the description of the present disclosure, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings for the convenience of describing the present disclosure and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0097] While specific embodiments of the present disclosure have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of protection of the present disclosure is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present disclosure, and such changes and modifications are intended to fall within the scope of protection of the present disclosure.

Claims

1. An insulating film of a battery cell shell, the battery cell shell comprising an opposite bottom surface and a top surface, an opposite first side surface and a second side surface, and an opposite third side surface and a fourth side surface, characterized in that: The insulating film of the battery cell shell includes a first insulating film, a second insulating film, a third insulating film and a fourth insulating film which are independent of each other; The first insulating film and the second insulating film are arranged opposite to each other and spaced apart along a first direction, the first insulating film is used to cover the first side surface, and the second insulating film is used to cover the second side surface; The third insulating film and the fourth insulating film are arranged opposite to each other, the third insulating film is used to cover at least the junction between the third side surface and the bottom surface and the junction between the third side surface and the top surface, so that the third side surface is partially exposed; the fourth insulating film is used to cover at least the junction between the fourth side surface and the bottom surface and the junction between the fourth side surface and the top surface, so that the fourth side surface is partially exposed; The first direction is a spacing direction between the first side surface and the second side surface.

2. The insulating film of the battery cell casing according to claim 1, characterized in that: The third insulating film is used to cover part of the third side surface, and the fourth insulating film is used to cover part of the fourth side surface; both ends of the third insulating film and the fourth insulating film in the first direction are connected to the first insulating film and the second insulating film respectively.

3. The insulating film of the battery cell casing according to claim 2, characterized in that: The third insulating film includes a first insulating film unit and a second insulating film unit that are independent of each other, the first insulating film unit and the second insulating film unit are arranged at intervals along the second direction, the first insulating film unit is used to cover at least the junction between the third side surface and the bottom surface and part of the third side surface, the second insulating film unit is used to cover at least the junction between the third side surface and the top surface and part of the third side surface, and both ends of the first insulating film unit and the second insulating film unit in the first direction are connected to the first insulating film and the second insulating film respectively; The fourth insulating film includes a third insulating film unit and a fourth insulating film unit which are independent of each other, wherein the third insulating film unit and the fourth insulating film unit are arranged at intervals along the second direction. The third insulating film unit is used to cover at least the junction between the fourth side surface and the bottom surface and part of the fourth side surface, the fourth insulating film unit is used to cover at least the junction between the fourth side surface and the top surface and part of the fourth side surface, and both ends of the third insulating film unit and the fourth insulating film unit in the first direction are connected to the first insulating film and the second insulating film respectively; The second direction is a spacing direction between the bottom surface and the top surface.

4. The insulating film of the battery cell casing according to claim 3, characterized in that: The first insulating film includes a first side covering area, a second side covering area, a third side covering area, a first bottom covering area and a first top covering area; the first side covering area is used to cover the first side; the first side covering area extends toward the third side to form the second side covering area, and the second side covering area is used to cover part of the third side; the first side covering area extends toward the fourth side to form the third side covering area, and the third side covering area is used to cover part of the fourth side; the first side covering area extends toward the bottom surface to form the first bottom covering area, and the first bottom covering area is used to cover at least part of the bottom surface; the first side covering area extends toward the top surface to form the first top covering area, and the first top covering area is used to cover at least part of the top surface; The second insulating film includes a fourth side covering area, a fifth side covering area, a sixth side covering area, a second bottom covering area and a second top covering area; the fourth side covering area is used to cover the second side; the fourth side covering area extends toward the third side to form the fifth side covering area, and the fifth side covering area is used to cover part of the third side; the fourth side covering area extends toward the fourth side to form the sixth side covering area, and the sixth side covering area is used to cover part of the fourth side; the fourth side covering area extends toward the bottom surface to form the second bottom covering area, and the second bottom covering area is used to cover at least part of the bottom surface; The fourth side surface covering area extends toward the top surface to form the second top surface covering area, and the second top surface covering area is used to cover at least a portion of the top surface; The second side coverage area and the fifth side coverage area are spaced apart in the first direction. The third side covering area and the sixth side covering area are arranged at intervals in the first direction.

5. The insulating film of the battery cell casing according to claim 4, characterized in that: The first insulating film unit includes a seventh side surface covering area and a third bottom surface covering area, the seventh side surface covering area is used to cover part of the third side surface, and the second side surface covering area and the fifth side surface covering area both overlap at least partly with the seventh side surface covering area; the seventh side surface covering area extends toward the bottom surface to form the third bottom surface covering area, the third bottom surface covering area is used to cover at least part of the bottom surface, and the first bottom surface covering area and the second bottom surface covering area both overlap at least partly with the third bottom surface covering area; The second insulating film unit comprises an eighth side surface covering area and a third top surface covering area, the eighth side surface covering area is used to cover part of the third side surface, and the second side surface covering area and the fifth side surface covering area both at least partially overlap with the eighth side surface covering area; The eighth side surface covering area extends toward the top surface to form the third top surface covering area, the third top surface covering area is used to cover at least a portion of the top surface, and the first top surface covering area and the second top surface covering area both overlap at least partially with the third top surface covering area; The third insulating film unit includes a ninth side surface covering area and a fourth bottom surface covering area, the ninth side surface covering area is used to cover part of the fourth side surface, the third side surface covering area and the sixth side surface covering area are at least partially overlapped with the ninth side surface covering area; the ninth side surface covering area extends toward the bottom surface to form the fourth bottom surface covering area, the fourth bottom surface covering area is used to cover at least part of the bottom surface, the first bottom surface covering area and the second bottom surface covering area are at least partially overlapped with the fourth bottom surface covering area; The fourth insulating film unit comprises a tenth side surface covering area and a fourth top surface covering area, the tenth side surface covering area is used to cover part of the fourth side surface, and the third side surface covering area and the sixth side surface covering area both at least partially overlap with the tenth side surface covering area; The tenth side surface covering area extends toward the top surface to form the fourth top surface covering area, wherein the fourth top surface covering area is used to cover at least a portion of the top surface, and the first top surface covering area and the second top surface covering area both at least partially overlap with the fourth top surface covering area.

6. The insulating film of the battery cell casing according to claim 5, characterized in that: At least one of the third insulating film and the fourth insulating film covers one end surface of the first insulating film and the second insulating film away from the battery cell case, and the third insulating film and / or the fourth insulating film has an adhesive layer on one end surface facing the first insulating film and the second insulating film.

7. The insulating film of the battery cell casing according to claim 4, characterized in that: The first bottom surface covering area and the second bottom surface covering area are arranged at intervals in the first direction, and the third insulating film and the fourth insulating film are arranged at intervals in the third direction so that the bottom surface is partially exposed; Wherein, the third direction is a spacing direction between the third side surface and the fourth side surface.

8. A battery cell, characterized in that: A battery cell shell, a battery cell assembly and an insulating film of the battery cell shell as claimed in any one of claims 1 to 7, wherein the battery cell assembly is accommodated in the battery cell shell, and the insulating film of the battery cell shell is coated on the outer surface of the battery cell shell; The outer surface of the battery cell case includes an opposite bottom surface and a top surface, an opposite first side surface and a second side surface, and an opposite third side surface and a fourth side surface; the first insulating film covers the first side surface; the second insulating film covers the second side surface; the third insulating film at least covers the junction between the third side surface and the bottom surface and the junction between the third side surface and the top surface, so that the third side surface is partially exposed; The fourth insulating film at least covers a boundary between the fourth side surface and the bottom surface and a boundary between the fourth side surface and the top surface, so that the fourth side surface is partially exposed.

9. A secondary battery, characterized in that: It comprises a battery case and a plurality of battery cells as claimed in claim 8, wherein the battery case has a receiving cavity, the plurality of battery cells are received in the receiving cavity, and the plurality of battery cells are arranged in sequence along the first direction.

10. The secondary battery according to claim 9, characterized in that The secondary battery meets one or more of the following conditions: a. The third side surface and / or the fourth side surface partially exposes a first connecting portion forming the battery cell housing, a fixing adhesive layer is provided on the first connecting portion, and the battery cell is bonded to the inner wall of the accommodating cavity or the adjacent battery cell through the fixing adhesive layer; b. The bottom surface partially exposes a second connection portion forming the battery cell housing, a thermal conductive adhesive layer is provided on the second connection portion, and the battery cell is bonded to the inner wall of the accommodating cavity or the adjacent battery cell through the thermal conductive adhesive layer.

Images